WO2010091330A1

WO2010091330A1 - Spray device having an adjustment member for needle valve opening range

Info

Publication number: WO2010091330A1
Application number: PCT/US2010/023439
Authority: WO
Inventors: Shigefumi Hashimoto; Toshihiro Nishikawa
Original assignee: Illinois Tool Works Inc.
Priority date: 2009-02-09
Filing date: 2010-02-08
Publication date: 2010-08-12
Also published as: TWI496620B; JP2010179284A; CA2750848C; BRPI1007001A2; ES2582792T3; CN102307671B; JP5412668B2; EP2393606A1; CN102307671A; EP2393606B1; CA2750848A1; AU2010210446B2; AU2010210446A1; TW201039924A

Abstract

[Issue] To provide a spray device which makes it possible to simply adjust the amount of paint ejected, and in which the nozzle can be effectively cleaned. [Means of Resolution] The spray device 400 according to the present invention is provided with a nozzle 122, a needle 150 for opening and closing a paint ejection orifice, a front piston 170 which is fixed to the needle, and a needle spring 174 for pushing the front piston. Provision is further made for a needle position adjustment mechanism for adjusting the position of the needle 150 in the direction along the center axis of the nozzle. The needle position adjustment mechanism includes an adjustment member 430 which is rotatable with the center axis of the nozzle 122 at the center, and a rotation position setting member 450 for setting the position of the front piston 170 along the center axis of the nozzle in correspondence to the angle of rotation of the adjustment member.

Description

SPRAY DEVICE HAVING AN ADJUSTMENT MEMBER FOR NEEDLE VALVE OPENING RANGE

[TECHNICAL FIELD]

[0001] The present invention relates to a spray device for spraying paint onto an object to be coated. More specifically, the present invention relates to a spray device wherein the needle can move in the axial direction. The present invention further relates to a spray device which can spray not only paint but also various kinds of liquids, including water, adhesives, rust prevention agents, insulating agents, coating agents and drugs onto an object to be sprayed, and which is provided with a manual adjustment member (adjustment knob) .

[PRIOR ART]

[0002] With plate-type automatic guns, which are spray devices for spraying paint onto an object to be coated, one or more of these guns are normally arranged on a coating line as automatic spray guns for coating. There are many kinds of line, such as suspended- or floor-type conveyors, and there are also lines in which the conveyor speed is fixed and cyclical-type lines. Furthermore, the objects to be coated may be moved individually, the objects to be coated may be caused to rotate, a plurality of objects to be coated may be suspended from the same hanger, or a plurality of objects to be coated may be lined up in a circular fashion and rotated on a cyclical-type line.

[0003] The method of arranging automatic spray guns may involve a fixed system, robots may be made to hold the automatic spray guns, one or more automatic spray guns may be mounted on a device known as a "reciprocating engine" which moves vertically or longitudinally (from front to back) on the same straight line, or the above configurations may be combined.

[0004] The actual user normally handles a range of objects to be coated, and objects to be coated which are the same are often divided up for coating with many different colors. It is also known that there are various shapes and sizes of objects to be coated.

[0005] The coating involves a primer or a base coat, and use is made of diverse coatings such as single-color coatings known as solid coatings, metallic coatings (normally aluminum powder) , pearl coatings, mica coatings, beads (glass) coatings, clear (transparent) coatings, and color- clear (colored transparent) coatings. The solvent may be solvent-based, of the high-solid-type (with a small proportion of solvent) or water-based, etc. Many different kinds of resin may be used, such as melamine, fluorine, acrylic or urethane. The coating process may involve an undercoat, middle coat and top coat, and such processes entail various steps and requirements.

[0006] For example, a first conventional type of system has a configuration in which a spray gun is provided with a remote control-type displacement mechanism allowing a stopper to be displaced between two preset positions, and the degree of opening of the discharge orifice can be remotely controlled in two stages, namely fully open and half open (see Patent Document 1) .

[0007] A second conventional type of system has a configuration in which a first rear end striking position of a needle valve is momentarily lowered to a second rear end striking position of the needle valve by releasing the drive force of a cylinder, and accumulated matter inside an ejection flow path is discharged, after which the cylinder is driven to instantly return to the first rear end striking position of the needle valve, whereby the initial set amount of coating is restored. The position of the end part when the cylinder piston has advanced is adjusted by a piston forward-end adjustment screw (see Patent Document 2) . [0008] In a third conventional type of system, a spray device is provided with a gun unit for atomizing paint for ejection, and a bracket unit for receiving paint and air. The bracket unit is detachably fixed to the gun unit. Paint is ejected from a paint ejection orifice by movement of a nozzle open/close valve to the rear (see Patent Document 3) .

[0009] A fourth conventional type of system has a configuration in which the rear end of a needle valve in a spray gun is fixed by a screw to a first piston which is disposed at the rear, and a second piston is disposed in front of the first piston. Compressed air is supplied to a first air supply passage which causes the first piston to move, or compressed air is supplied to a second air supply passage which causes the second piston to move, so that the amount of movement of the needle valve is changed and varying amounts of discharge are produced (see Patent Document 4) .

[0010] In a fifth conventional type of system, a first controlling member which can be adjusted to the front and rear by a screw is provided on a cylinder end cover. The tip end of the first controlling member is made to respond to a spring receiving member. A second controlling member which can be adjusted from the outside by a screw is linked by a screw and provided in the spring receiving member (see Patent Document 5) .

[0011] In a sixth conventional type of system, a first controlling member which can be adjusted to the front and rear by a screw is provided on a cylinder end cover. The tip end of the first controlling member is made to respond to a spring receiving member. A second controlling member which can be adjusted from the outside by a screw is linked by a screw and provided in the spring receiving member (see Patent Document 6) . [0012] In a seventh conventional type of system, an open/close valve with a flow rate control function is provided with a long spring and a short spring as reverting springs. Increases and reductions in the pilot air pressure are used to open a needle valve body in stages, thereby adjusting the flow rate (see Patent Document 7) .

[0013] In an eighth conventional type of system, a needle valve body in a needle valve for supplying paint is switched between a small flow passage open position and a large flow passage open position (see Patent Document 8) .

[0014] A ninth conventional type of system has a configuration in which, in a needle valve for a spray gun, a second piston is displaced to a locking position provided at a first piston by pumping air to a second cylinder chamber so that a paint discharge orifice is half-opened. The first piston is displaced along with the second piston by pumping air to a first cylinder chamber so that the paint discharge orifice is fully opened (see Patent Document 9) .

[PRIOR ART DOCUMENTS]

[0015]

[Patent Document 1] Japanese Unexamined Patent Application Publication S59-62360

[Patent Document 2] Japanese Unexamined Patent Application Publication 2003-205258

[Patent Document 3] Japanese Unexamined Patent Application Publication 2008-649

[Patent Document 4] Japanese Unexamined Patent Application Publication 2008-12404

[Patent Document 5] Japanese Examined Utility Model Application Publication S63-38929

[Patent Document 6] Japanese Unexamined Utility Model Application Publication S60-13264

[Patent Document 7] Japanese Unexamined Utility Model Application Publication H5-71547 _ o

[Patent Document 8] Japanese Examined Utility Model

Application Publication H3-36779

[Patent Document 9] Japanese Examined Utility Model

Application Publication S48-14667

[SUMMARY OF THE INVENTION]

[ISSUES TO BE RESOLVED BY THE INVENTION]

[0016] Looking at the above, frequent changes of color and cleaning operations are anticipated with spray devices, and it is desirable for such changes of color and cleaning to be carried out quickly and reliably in an automatic manner. When the spray guns in conventional spray coating devices are overhauled, it is necessary to remove the nozzle from the spray gun body. A further point with conventional spray coating devices is that the piston members and body members have a complex structure, which means that production and assembly require a large amount of time.

[0017] Looking at Figure 19, a conventional adjust type spray coating device 900 has a gun body 910 and a rear body 930. A fluid tip 912, a needle 914, and a front piston 916 are disposed in the gun body 910. The front piston 916 is urged forward by means of a spring 918. A front piston seal 920 closes off (seals) the front piston 916 and the gun body 910.

[0018] The degree of opening (clearance) of the fluid tip 912 and the needle 914 can be adjusted by means of an adjustment knob 932 and a lock nut 934 which are disposed at the rear. With this spray coating device 900, coating is carried out with the degree of opening of the needle 914 during coating being set to a position in which the adjustment knob 932, which is the adjustment member, is rotated to 1.5 from fully open, or to a position in which the adjustment knob 932 is rotated to 2.0 from fully open. When a change of color is required for the object being coated on the coating line, a cleaning process is carried out, and the coating apparatus (spray coating device) is filled with paint of a different color than the color of paint which was being coated until that point. At such times, when the degree of opening (clearance) of the fluid tip 912 and the needle 914 is narrow, the cleaning (use of solvent) is time consuming and leads to production losses and therefore the adjustment knob is often adjusted for a time during cleaning to the fully open position, in other words to a position in which it has been rotated to 4.0 or 5.0.

[0019] The problem in this case is that once the cleaning process has been completed, the degree of opening (clearance) of the fluid tip 912 and the needle 914 needs to be returned to the original state, but the conventional adjustment knob 932 employs a spring system, and the adjustment knob 932 has a structure which is fixed by means of the lock nut 934, and therefore it is difficult to reliably adjust the adjustment knob 932 to its original position, and the adjustment is time consuming. If the adjustment knob 932 is wrongly adjusted, the amount of paint sprayed from the spray coating device 900 fluctuates, and there is a risk of coating defects occurring.

[0020] The aim of the present invention is to provide a spray device in which coating operations when the nozzle of the spray device is being cleaned can be carried out effectively, and in which the time needed to change paint is shortened and the device can deal with painting operations involving a large number of colors.

A further aim of the present invention is to provide a spray device which makes it possible to adjust the amount of paint ejected simply and in a short time.

A further aim of the present invention is to provide a spray device which can be easily produced and assembled. A further aim of the present invention is to provide a spray device which can be easily realized with any of the conventional adjust type, air-type two-stage-pull type and manual multiple-stage type structures.

[MEANS OF RESOLVING THE ISSUES]

[0021] The present invention concerns a spray device for spraying paint from a paint ejection orifice, which is provided with: a nozzle having a paint ejection orifice for atomizing and ejecting paint; a needle for opening and closing the paint ejection orifice; a front piston which is fixed to the needle; a needle spring which is provided so as to push the front piston toward the paint ejection orifice; a gun body which accommodates the nozzle and accommodates the front piston; a rear body which is disposed to the rear of the gun body; a needle position adjustment mechanism for adjusting the position of the needle in a direction along the center axis of the nozzle; and a bracket unit which is detachably fixed to the gun body.

[0022] When the bracket unit is fixed to the gun body, the paint and air contained in the bracket unit flow through the gun body. The needle position adjustment mechanism includes an adjustment member which is rotatable with the center axis of the nozzle at the center, and a rotation position setting member for setting the position of the front piston along the center axis of the nozzle in correspondence to the angle of rotation of the adjustment member.

[0023] The needle position adjustment mechanism is adjusted so that when the front piston moves together with the needle along the center axis of the nozzle in a direction away from the paint ejection orifice in a state in which the amount of discharge paint exiting the paint ejection orifice has been set, the front piston and the needle come together and move in a direction away from the paint ejection orifice. The spray device having this configuration is simple to disassemble, assemble, maintain, and the components on the gun body side are simple to replace. With the spray device according to the present invention, the amount of paint discharged can be easily adjusted, and the nozzle can be effectively cleaned.

[0024] With the spray device according to the present invention, the needle position adjustment mechanism includes an adjustment knob which is rotatable with the center axis of the nozzle at the center, and a rotational stopper for setting the position of the front piston along the center axis of the nozzle in correspondence to the angle of rotation of the adjustment member. The outer peripheral part of the cylindrical section of the front piston is slidably disposed within the inner peripheral part of the cylindrical section of the rotational stopper.

[0025] With the spray device according to the present invention, a plurality of counterbored holes are formed in the rotational stopper, and a rotational stopper positioning pin is provided in the rear body; and the rotational stopper positioning pin can be positioned in the counterbored holes by moving the adjustment knob in the direction along the center axis of the nozzle and causing the rotation of the adjustment knob.

[0026] The spray device according to the present invention can also be used in a fixed system; it can also be used in a system in which a robot is made to hold an automatic spray gun; it can be used in a system in which one or more automatic spray guns are mounted on a device known as a "reciprocating engine"; or it may be used in a system combining the above configurations.

[0027] When coating operations are carried out with the spray device according to the present invention, the needle position adjustment mechanism is used to cause the adjustment member to rotate with the center axis of the nozzle at the center, so that the position of the front piston along the center axis of the nozzle is set in the coating operation position. Front piston operating air is then sent to the gun unit from a supply source for front piston operating air, and the needle is moved back and paint is ejected from the paint ejection orifice. At this point, atomized air is introduced from an atomized air supply source, and atomized air is ejected from an atomized air orifice so that the paint which has been ejected from the paint ejection orifice can be atomized. Also at this point, pattern air is introduced from a pattern air supply source and the pattern air is ejected from a pattern air orifice so that a pattern of atomized paint can be formed. The remaining paint which has not been ejected from the paint ejection orifice can be returned to the paint supply source (or paint tank) . It is possible to construct a paint circulation line in this way.

[0028] When metal powder or the like is contained in the paint, as with metallic paints, then if the paint circuit remains closed for a long time, the heavier content tends to settle (precipitate) , and there is a risk of painting defects and clogging of the paint circuit. In such cases therefore, a circulating-type structure is preferred. It is also possible to adopt a non-circulating-type configuration which does not have a return path. The spray device according to the present invention may also be used to automatically or manually spray not just paint, but various kinds of liquids, including water, adhesives, rust prevention agents, insulating agents, coating agents and drugs .

[0029] When the nozzle of the spray gun body in the spray device according to the present invention is cleaned, the needle position adjustment mechanism is used to cause the adjustment member to rotate with the center axis of the nozzle at the center so that the position of the front piston along the center axis of the nozzle is set in the cleaning operation position. While front piston operating air is introduced from a supply source for front piston operating air into a front piston operating chamber, a state is maintained in which the needle and the front piston come together and move backward along the center axis of the nozzle in resistance to the spring force of the needle spring. The nozzle can be cleaned in this state.

[EFFECTS OF THE INVENTION]

[0030] With the spray device according to the present invention, it is possible to set the amount by which the needle can move- backward from the closed nozzle state to the cleaning state to be sufficiently large. This means that the cleaning operation when the nozzle of the spray device is cleaned can be carried out efficiently, and the downtime of the coating operations can be shortened. Furthermore, with the spray device according to the present invention, the time required for changing the paint can be shortened, and it is possible to deal with painting operations involving a large number of colors. Furthermore, the spray device according to the present invention has a detachable unitary structure, and therefore it is simple to produce and assemble each of the components making up the unit.

[0031] Furthermore, the spray device according to the present invention has the configuration described above, and therefore the cleaning time is significantly reduced and enhanced performance can be achieved in terms of significantly improved operating efficiency, among other things, compared with a conventional spray device. With conventional spray devices, it is necessary to open a manual knob when "fully open" is required. Consequently, in most cases when the needle position is to be returned to the original position, the readjustment needs to be carried out manually and depends on the feeling and vision of the operator.

[0032] In addition, the spray device according to the present invention can be easily realized with any of the three types of conventional spray devices, namely adjust type, air-type two-stage-pull type and manual multiple-stage type spray devices. By introducing spray devices such as these three types, each user of the spray device can select the type of spray device to match the type of line, the state of equipment, color changes in objects to be coated (products), and type of paint used etc., and it is also possible to use several types of spray device conjointly. That is to say, it is possible to increase the value of the objects to be coated by means of a synergistic effect achieved by using three types of spray device, making it possible to achieve a distinction with standard products and making it possible to anticipate ease in selling the products .

[0033] In addition, with a manual multiple-stage type spray device according to the present invention, there is one less air circuit than with an air-type two-stage-pull type spray device (the same as with a conventional adjust type spray device) , and therefore when a conventional adjust type spray device is being used, it is possible to replace this with a manual multiple-stage type spray device according to the present invention without adding an air circuit.

[BRIEF DESCRIPTION OF THE FIGURES]

[0034] [Figure 1] is a view in longitudinal section showing the structure of a spray device in the closed nozzle state, in accordance with a mode of embodiment of the present invention;

[Figure 2] is a front view showing the structure of the gun unit, in accordance with a mode of embodiment of the present invention;

[Figure 3] is a side view showing the structure of the spray device, in accordance with a mode of embodiment of the present invention;

[Figure 4] is a back view showing the structure of the gun unit, in accordance with a mode of embodiment of the present invention; [Figure 5] is a back view showing the structure of the gun unit and the bracket unit, in accordance with a mode of embodiment of the present invention;

[Figure 6] is a view in longitudinal section showing a structure containing the flow passage of the spray device, in accordance with a mode of embodiment of the present invention;

[Figure 7] is a schematic in cross section showing the arrangement of the flow passages of the spray device, in accordance with a mode of embodiment of the present invention;

[Figure 8] is an exploded assembly drawing showing the structure of the rear body, rotational stopper and adjustment knob, in accordance with a mode of embodiment of the present invention;

[Figure 9] shows the structure of the rear body, rotational stopper and adjustment knob, in accordance with a mode of embodiment of the present invention, where Figure 9 (a) is a front view, Figure 9 (b) is a cross-sectional view, Figure

9 (c) is a side view, and Figure 9 (d) is a back view;

[Figure 10] is an oblique view showing the structure of the rotational stopper, in accordance with a mode of embodiment of the present invention;

[Figure 11] shows the structure of the rotational stopper, in accordance with a mode of embodiment of the present invention, where Figure 11 (a) is a front view, Figure 11 (b) is a cross-sectional view, Figure 11 (c) is a side view, and

Figure 11 (d) is a back view;

[Figure 12] shows the structure of the adjustment knob, in accordance with a mode of embodiment of the present invention, where Figure 12 (a) is a front view of the adjustment knob, Figure 12 (b) is a cross-sectional view of the adjustment knob, Figure 12 (c) is a side view of the adjustment knob, and Figure 12 (d) is a back view of the adjustment knob;

[Figure 13] is a view in longitudinal section showing the structure of the spray device in the state of the first discharge amount of the nozzle, in accordance with a mode of embodiment of the present invention;

[Figure 14] is a view in longitudinal section showing the structure of the spray device in the state of the second discharge amount of the nozzle, in accordance with a mode of embodiment of the present invention;

[Figure 15] is a view in longitudinal section showing the structure of the spray device in the state of the third discharge amount of the nozzle (nozzle cleaning state) , in accordance with a mode of embodiment of the present invention;

[Figure 16] is a view in longitudinal section showing the structure of the spray device in a state in which the nozzle is closed when an air-type two-stage-pull type spray device is configured using the gun unit according to the present invention;

[Figure 17] is a view in longitudinal section showing the structure of the spray device with the nozzle in a first open state when an air-type two-stage-pull type spray device is configured using the gun unit according to the present invention;

[Figure 18] is a view in longitudinal section showing the structure of the spray device with the nozzle in a second open state (nozzle cleaning state) when an air-type two- stage-pull type spray device is configured using the gun unit according to the present invention; and

[Figure 19] is a view in longitudinal section showing the structure of the spray device in a state in which the nozzle is closed in a conventional adjust type spray device;

[MODE OF EMBODIMENT OF THE INVENTION]

[0035] (1) Configuration of the spray device:

A mode of embodiment of the present invention will be described below in conjunction with the figures. The mode of embodiment of the present invention described below relates to a spray device for spraying paint onto an object, but it should be noted that the spray device according to the present invention can be widely applied, not only to paint, but also to various kinds of liquids, including water, liquid-type adhesives, liquid-type rust prevention agents, liquid-type insulating agents, liquid-type coating agents and liquid-type drugs.

[0036] The spray device according to the present invention may be referred to as a "manual two-stage-pull type" spray device, but in this instance "two-stage pull" means both an arbitrary position (pull-back of the needle) and the CLEAN position. The spray device according to the present invention therefore relates to a "manual multiple-stage type" spray device in which the needle can be set in a plurality of positions. The mode of embodiment of the spray device according to the present invention which will be described below relates to a spray device in which the needle can be set in three positions (a position in which a first discharge amount can be ejected, a position in which a second discharge amount can be ejected, and a cleaning position) , but it should be noted that the spray device according to the present invention can equally be applied to a spray device in which the needle can be set in two positions, or it can be applied to a spray device in which the needle can be set in three or more positions (a position in which a first discharge amount can be ejected, a position in which a second discharge amount can be ejected, ... , a position in which an N^th discharge amount can be ejected, and a cleaning position) .

[0037] Looking at Figures 1 to 3, showing a mode of embodiment of the present invention, a spray device 400 for spraying paint onto an object to be coated from a paint ejection orifice of a nozzle is provided with a gun unit 110 for atomizing and ejecting paint, a bracket unit 210 which constitutes a manifold for receiving paint and air, and a rear body 420. The bracket unit 210 is designed so that it can be detachably fixed to the gun unit 110 by using a unit fixing device such as a bolt 220 with a hexagonal hole. For example, the bracket unit 210 is disposed on one face of the gun unit 110. The rear body 420 is disposed to the rear of the gun unit 110.

[0038] (2) Configuration of the gun unit:

Looking at Figures 1 to 4, the gun unit 110 is provided with a gun body 112 which constitutes a base member; a nozzle 114 which is supported in front of the gun body 112; an air cap 120 which is supported in front of the nozzle 114; a retaining ring 128 which supports the air cap 120 on the gun body 112; and the rear body 420 which is disposed to the rear of the gun body 112. The gun body 112 is preferably formed from engineering plastic which is rigid and resistant to solvents.

[0039] The gun body 112 is formed from POM (polyoxymethylene) , for example. The rear body 420 is preferably formed from POM (polyoxymethylene), for example. POM (polyoxymethylene) is resistant to solvents and can cope with aqueous systems. This structure makes it possible to reduce the weight of the gun body 112. If several spray devices are mounted on a robot or a reciprocating engine, there may be limitations on the loading weight (loading capacity) or the range of operation, in which case it is necessary to reduce the weight of the gun body 112. Moreover, if there is no need to reduce the weight, it is possible to use a conventional article made of aluminum (alumite treated) , stainless steel or heat-treated stainless steel .

[0040] A guide pin 112P for guiding the bracket unit 210 is provided on the lower surface of the gun body 112. A female thread part 112F for screwing tight the bolt 220 with a hexagonal hole which fixes the bracket unit 210 is provided on the lower surface of the gun body 112. Only one guide pin 112P is depicted, but two guide pins 112P are preferably provided. There may be one guide pin 112P, or there may be two. [0041] Here, the terms "front" and "in front" refer to the direction in which paint is ejected from the gun unit 110. Furthermore, "rear" and "behind" refer to the opposite direction to the direction in which paint is ejected from the gun unit 110.

[0042] The nozzle 114 has a cylindrical shape and dictates the center axis 114A of the nozzle. The nozzle 114 includes a nozzle body 114B and a nozzle tip 114C. The tip end of the nozzle tip 114C has a tapered shape. The nozzle tip 114C is preferably formed from tungsten alloy. The nozzle body 114B is supported on the gun body 112 by means of a first threaded strengthening ring 115 and a second threaded strengthening ring 116. A first stop pin 117 positions the second threaded strengthening ring 116 on the gun body 112. The first threaded strengthening ring 115 is positioned further forward than and to the outside of the second threaded strengthening ring 116. The first threaded strengthening ring 115 is preferably fixed to the gun body 112 by secure fastening using a pin (not depicted) . Heliserts (commercially available threaded strengthening components) are preferably used for the threaded part of the gun body 112.

[0043] Looking at Figures 1 and 2, a paint ejection orifice 122 for ejecting paint is provided at the tip end of the nozzle tip 114C. The inside of the nozzle 114 is designed to allow the flow of liquid paint. The air cap 120 has an auxiliary atomized air orifice 124. The tip end of the nozzle 114 is disposed inside the nozzle orifice of the air cap 120. The center axis of the paint ejection orifice 122 lies on the center axis 114A of the nozzle. The center of the nozzle orifice of the air cap 120 lies on the center axis 114A of the nozzle. Provision is made for a pattern air orifice 126 for ejecting air in order to form a pattern with the paint which has been atomized and ejected from the paint ejection orifice 122. A plurality of pattern air orifices 126 are preferably concentrically disposed with the center axis 114A of the nozzle at the center.

[0044] A plurality of auxiliary atomized air orifices 124 are preferably concentrically disposed with the center axis 114A of the nozzle at the center. Alternatively, a plurality of auxiliary atomized air orifices 124 may be concentrically disposed around a first radius with the center axis 114A of the nozzle at the center, and they may also be concentrically disposed around another radius other than the first radius (second radius or second and third radii etc.) with the center axis 114A of the nozzle at the center.

[0045] Looking at Figure 1, the gun unit 110 is provided with a nozzle open/close valve, i.e. a needle 150, for opening and closing the paint ejection orifice 122; a needle seal kit 160 which is disposed inside the gun body 112 and supports the needle 150; and a front piston 170 which is disposed to the rear of the needle seal kit 160 inside the gun body 112. The needle seal kit 160 is disposed to the rear of the nozzle 114. The needle 150 includes a needle tip 150C which is positioned at the front, and a needle main body 150B which is positioned at the rear. The rear part of the needle tip 150C is fixedly fitted into the front part of the needle main body 150B. The center axis of the needle tip 150C lies on the center axis 114A of the nozzle. The center axis of the needle main body 150B lies on the center axis 114A of the nozzle. Accordingly, the center axis of the needle 150 lies on the center axis 114A of the nozzle.

[0046] The needle tip 150C is preferably formed from tungsten alloy. The needle main body 150B is preferably formed from stainless steel (SUS304, for instance) and preferably undergoes a hard chromium treatment. By forming the needle tip 150C from tungsten alloy it is possible to significantly improve durability compared with conventional components which are formed from SUS303. This constitution makes it possible to prevent spitting caused by wear (in other words a defect which is one kind of coating problem caused by leakage of liquid from the tip end of the nozzle) . At the same time, this constitution makes it possible to simplify maintenance of the needle 150 and to postpone the time when the needle 150 needs replacing. In addition, if the needle main body 150B undergoes a hard chromium treatment, it is possible to avoid problems caused by leakage of liquid from the needle seal part due to wear of the needle main body 150B, and this makes it possible to simplify maintenance of the needle 150 and to postpone the time when the needle 150 needs replacing.

[0047] A third threaded strengthening ring 142 is fixed to the gun body 112 by means of a third threaded strengthening ring stop pin 140. The third threaded strengthening ring 142 has a female thread part for fixing the needle seal kit 160 by screwing. The needle seal kit 160 has a male thread part so that it can be fixed by screwing. By screwing the male thread part of the needle seal kit 160 into the female thread part of the third threaded strengthening ring 142 it is possible to detachably fix the needle seal kit 160 to the gun body 112.

[0048] The needle seal kit 160 includes: a collar 160A; a seal stopper 160B positioned to the rear; a first general seal 160C; a seal housing 160D; a first O-ring 160E; a second general seal 160F; a second O-ring 160G; and a front seal 160H positioned at the front. The center axis of the needle seal kit 160 lies on the center axis 114A of the nozzle. The second O-ring 160G is positioned further forward than the first O-ring 160E. The second general seal 160F is positioned further forward than the first general seal 160C. The second general seal 160F is held inwardly in front of the seal housing 160D by means of the front seal 160H. The first general seal 160C is held inwardly to the rear of the seal housing 160D by means of the seal stopper 160B. The seal stopper 160B is held inwardly to the rear of the seal housing 160D by means of the collar 160A. The second general seal 160F and the first general seal 160C are provided in order to seal the seal housing 160D and the needle main body 150B. The first 0-ring 160E and the second O-ring 160G are provided in order to seal the seal housing 160D and the gun body 112.

[0049] The first O-ring 160E and the second O-ring 160G are preferably perfluoro 0-rings. Rubber-based materials generally have low resistance to solvents and there is a large possibility of deformation and expansion. When the product is mainly to be applied to coating and solvents are used for overhauling and maintenance, perfluoro is preferably used in order to avoid problems in terms of not being able to assemble the 0-rings or the O-rings not moving.

[0050] The needle seal kit 160 has a structure such that it can be replaced by removing it as a single piece, and therefore maintenance of the gun is simplified. Two V seals which are used in the needle seal kit 160 have low resistance to sliding and therefore serve to prevent leakage of liquid caused by friction with the needle main body 150B and to improve durability. The front seal 160H is a component which doubles the front V seal function (the liquid sealing function) , and the sliding resistance (sealing state) thereof can be adjusted using the clamping state of the needle seal kit 160. Accordingly, the structure of the front seal 160H is such that when it is worn, a liquid sealing function is demonstrated by increasing the amount of clamping thereof. That is to say, the needle seal kit 160 is clamped and the tip end of the front seal 160H is flattened whereby a liquid sealing function is demonstrated.

[0051] The two O-rings on the outer side of the needle seal kit 160, in other words the first O-ring 160E and the second O-ring 160G, are such that the front-side second O-ring 160G demonstrates a liquid (paint) sealing function, and the rear-side O-ring 160E demonstrates an air sealing function with the gun body 112. Accordingly, this configuration makes it possible to significantly improve the durability of the needle seal kit 160, to simplify maintenance of the needle seal kit 160 and to postpone the time when the needle seal kit 160 needs replacing.

[0052] The front piston 170 is provided so as to be able to move along the center axis 114A of the nozzle. The front piston 170 is disposed to the rear of the needle seal kit 160. The front piston 170 includes a front piston shaft 170A, a front piston flange 170F which is provided in front of the front piston shaft 170A, and a front piston seal receiving part 170G which is provided at the outer periphery of the front piston flange 170F. A front piston hole 170H is provided in front of the front piston shaft 170A. A rear shaft part 150D which is provided to the rear of the needle main body 150B is fitted into the front piston hole 170H and fixedly attached therein.

[0053] A front piston seal 170C is disposed inside a groove in the front piston seal receiving part 170G. The front piston seal 170C is provided in order to seal a front piston main body 170B and the gun body 112. The front piston seal 170C is preferably made from perfluoro. This constitution makes it possible to reduce sliding resistance and improve durability.

[0054] The front piston main body 170B may be formed from aluminum alloy A2021 (alumite treatment may be carried out, for example) . A front piston operating chamber 176 is configured inside the gun body 112, in front of the front piston 170.

[0055] A needle spring 174 is provided in order to push the front piston main body 170B forward. The needle spring 174 may be formed by a coil spring made of stainless steel

(SUS304, for instance) . The needle spring 174 is disposed to the outer side of a rear shaft part 170D of the front piston main body 170B. The rear section of the needle spring 174 is disposed so as to come into contact with a planar section facing the front of a rotational stopper 450 (to be described later) . The front section of the needle spring 174 is disposed so as to come into contact with a section facing the rear of the front piston flange 170F of the front piston main body 170B. The center axis of the needle spring 174 may lie on the center axis 114A of the nozzle. The front piston 170 is subjected to force in a forward-moving direction by means of the elastic force of the needle spring 174. Accordingly, when compressed air is not introduced into the front piston operating chamber 176, the front piston 170 moves forward and the needle tip 150C of the needle 150 is designed to close off the paint ejection orifice 122.

[0056] Looking at Figures 1 and 4, the rear body 420 is fixed to the rear end of the gun body 112 by screw fastening, using rear body fixing bolts 192A, 192B. As depicted, the rear body 420 can be fixed to the gun body 112 using two rear body fixing bolts 192A, 192B, for example. The two rear body fixing bolts 192A, 192B may be disposed symmetrically about a point such that there is an angular interval therebetween of 180° with the center axis 114A of the nozzle at the center. There may be one, or two or more rear body fixing bolts. When several rear body fixing bolts are used, said rear body fixing bolts may be disposed such that there is an equal angular interval therebetween with the center axis 114A of the nozzle at the center.

[0057] The gun unit 110 is also provided with an adjustment knob 430 which constitutes the adjustment member for adjusting the position of the needle 150 along the center axis 114A of the nozzle, and a rotational stopper 450 for determining the position of the adjustment knob 430 in the direction of rotation. The adjustment knob 430 is designed to be able to rotate with the center axis 114A of the nozzle at the center. The adjustment knob 430 is disposed to the rear of the rear body 420. [0058] Looking at Figures 8 and 9, the rear body 420 includes a base part 422, an annular front recess 424 which is formed on the front side of the base part 422, and an annular rear projection 426 which is formed on the rear side of the base part 422. Two screw holes 426A, 426B are formed in the base part 422. Two bolts holes 420A, 420B may be provided at positions which are symmetrical about a point such that there is an angular interval therebetween of 180° with the center axis 114A of the nozzle at the center. A rear body center hole 420H is formed in the base part 422 with the center axis 114A of the nozzle at the center. The two screw holes 426A, 426B may be symmetrically disposed about a point such that there is an angular interval therebetween of 180° with the center axis 114A of the nozzle at the center. Two rotational stopper positioning pins 432A, 432B are fixed vertically with respect to a surface facing the front inside the rear projection 426 of the rear body 420, by means of pin fixing screws 440A, 440B. That is to say, the positions at the centers of the two rotational stopper positioning pins 432A, 432B are the same as the centers of the screw holes 426A, 426B, respectively.

[0059] Looking at Figures 8 to 11, the rotational stopper 450 is disposed within the front recess 424 in the rear body 420. The rotational stopper 450 includes a disk-shaped base part 452, an annular front shaft part 453 which is formed at the front side of the base part 452, and a columnar rear shaft part 454 which is formed at the rear side of the base part 452. A front hole part 455 is formed in the central part of the base part 452 and front shaft part 453. An adjustment knob locking screw part 456 is formed in the central part of the rear shaft part 454. Two rotational stopper positioning holes 457A, 457B are formed in the rear shaft part 454, in the area surrounding the adjustment knob locking screw part 456. In the mode of embodiment depicted, two rotational stopper positioning holes are provided, but there may be one, or two or more of these rotational stopper positioning holes. Furthermore, instead of providing the rotational stopper positioning holes it is possible to employ a different positioning structure comprising a recess and a projection, or a structure may be formed such that the rear part of the rotational stopper configures the adjustment knob. The plurality of rotational stopper positioning holes 457A, 457B may be provided symmetrically about a point taking the center axis of the rotational stopper 450 as a reference. The front ends of columnar rotational stopper positioning pins 468A, 468B are disposed in the respective rotational stopper positioning holes 457A, 457B.

[0060] Looking at Figure 8, marks 420M showing "CLEAN", "1.5", "2.0", "CLEAN", "1.5", "2.0" which indicate the position of the needle 150 are formed on the rear surface of the rear body 420 at angular intervals of 60°, for example. The mark "CLEAN" indicates the CLEAN position (corresponding to the cleaning position, which is to say a needle pull of 4.5 mm) . The mark "1.5" indicates the first discharge amount position (corresponding to the small amount of discharge position, which is to say a needle pull of 1.5 mm) . The mark "2.0" indicates the second discharge amount position

(corresponding to the large amount of discharge position, which is to say a needle pull of 2.0 mm). Using these three types of marks 420M it is possible to confirm the three set positions of the rotational stopper 450 in the direction of rotation.

[0061] Six counterbored holes 461 - 466 are formed on the rear side of the base part 452 of the rotational stopper 450 as "non-through holes (blind holes)". The center positions of the six counterbored holes 461 - 466 may lie at equal angular intervals with respect to one another and at equal distances taking the center axis of the rotational stopper 450 as a reference. However, the inner diameters of the counterbored holes 461 - 466 are preferably of the same size. The first counterbored hole 461 and the fourth counterbored hole 464 are formed to have equal depths. The second counterbored hole 462 and the fifth counterbored hole 465 are formed to have equal depths. The third counterbored hole 463 and the sixth counterbored hole 466 are formed to have equal depths. The first counterbored hole 461 and the fourth counterbored hole 464 are symmetrically provided about a point with the center axis of the rotational stopper 450 as a reference. The second counterbored hole 462 and the fifth counterbored hole 465 are symmetrically provided about a point with the center axis of the rotational stopper 450 as a reference. The third counterbored hole 463 and the sixth counterbored hole 466 are symmetrically provided about a point with the center axis of the rotational stopper 450 as a reference.

[0062] In the mode of embodiment depicted, there are two each of counterbored holes having three different depths. For example, the first counterbored hole 461 and the fourth counterbored hole 464 are formed with a depth of 3.5 mm and are set as the CLEAN position (corresponding to the cleaning position, which is to say a needle pull of 4.5 mm) . The second counterbored hole 462 and the fifth counterbored hole 465 are formed with a depth of 1.0 mm and are set as the second discharge amount position (corresponding to the large amount of discharge position, which is to say a needle pull of 2.0 mm) . The third counterbored hole 463 and the sixth counterbored hole 466 are formed with a depth of 0.5 mm and are set as the first discharge amount position

(corresponding to the small amount of discharge position, which is to say a needle pull of 1.5 mm) .

[0063] Looking at Figures 8, 9 and 12, the adjustment knob 430 is disposed at the rear side of the rear projection 426. The adjustment knob 430 includes a disk-shaped base part 432, a front recess 434 which is formed at the front side of the base part 432, and an annular front shaft part 435 which is formed at the front side of the base part 432, inside the front recess 434. A center hole 436 is formed in the central part of the base part 432 and the front shaft part 435. An adjustment knob locking screw plate 438 is formed in the central part of the base 432. The rear projection 426 which is formed at the rear side of the rear body 420 has a size and shape that allows it to move inside the front recess 434 of the adjustment knob 430.

[0064] Two rotational stopper pin holes 437A, 437B are formed in the front shaft part 435 in the area surrounding the center hole 436. In the mode of embodiment depicted, there are two rotational stopper pin holes, but one, or two or more rotational stopper pin holes may be provided. The plurality of rotational stopper pin holes 437A, 437B may be symmetrically provided about a point with the center axis of the rotational stopper 450 as a reference. The positions where the rotational stopper pin holes 437A, 437B are provided are determined in such a way as to correspond to the respective positions where the rotational stopper positioning holes 457A, 457B of the rotational stopper 450 are provided. The rear ends of the rotational stopper positioning pins 468A, 468B are disposed in the respective rotational stopper pin holes 437A, 437B.

[0065] Looking at Figure 8, two marks 430M for confirming the position of the rotational stopper 450 in the direction of rotation are formed on the rear surface of the adjustment knob 430 at an angular interval of 180°. The adjustment knob 430 is rotationally adjusted so that the marks 430M on the adjustment knob 430 and the marks 420M on the rear body 420 are aligned, whereby the position of the rotational stopper 450 in the direction of rotation can be confirmed.

[0066] Looking at Figures 8 and 9, the two rotational stopper positioning pins 432A, 432B are disposed in the front recess 424 of the base part 422 of the rear body 420, respectively, and the rotational stopper positioning pins 432A, 432B are fixed to the rear projection 426 by means of the pin fixing screws 440A, 440B. The front ends of the rotational stopper positioning pins 468A, 468B are disposed in the rotational stopper positioning holes 457A, 457B, respectively, and the rotational stopper 450 is disposed in the front recess 424 of the base part 422 of the rear body 420; the rear shaft part 454 of the rotational stopper 450 is designed to pass through the rear body center hole 420H, and the rear ends of the rotational stopper positioning pins 468A, 468B are disposed in the rotational stopper pin holes 437A, 437B, respectively, and the adjustment knob 430 is immobilized by screw fastening with respect to the rotational stopper 450 by means of an adjustment knob locking screw 430A.

[0067] When the marks 430M on the adjustment knob 430 are set in a position corresponding to "CLEAN" from the marks 420M on the rear body 420, the rotational stopper positioning pins 432A, 432B are designed to enter the first counterbored hole 461 and the fourth counterbored hole 464. When the marks 430M on the adjustment knob 430 are set in a position corresponding to "1.5" from the marks 420M on the rear body 420, the rotational stopper positioning pins 432A, 432B are designed to enter the third counterbored hole 463 and the sixth counterbored hole 466. When the marks 430M on the adjustment knob 430 are set in a position corresponding to "2.0" from the marks 420M on the rear body 420, the rotational stopper positioning pins 432A, 432B are designed to enter the second counterbored hole 462 and the fifth counterbored hole 465.

[0068] Looking at Figure 1, by moving the adjustment knob 430 forward, the rotational stopper positioning pins 432A, 432B are able to exit the counterbored holes. In this state, the adjustment knob 430 is rotated and the adjustment knob 430 is moved backward so that the rotational stopper positioning pins 432A, 432B enter any of the counterbored holes, and the rotational stopper positioning pins 432A, 432B can be positioned. [0069] Looking at Figures 1, 3, 4 and 9, the base part 422 of the rear body 420 is fixed by screw fastening to the rear end of the gun body 112, using the rear body fixing bolts 192A, 192B. By virtue of this configuration, the position of the needle 150 in the axial direction and the position of the front piston 170 in the axial direction can be accurately adjusted to three different positions. That is to say, with the configuration of the present invention, the adjustment knob 430 is rotated so that the position of the needle 150 in the axial direction and the position of the front piston 170 in the axial direction can be adjusted to the same positions, however many times the position of the needle 150 in the axial direction and the position of the front piston 170 in the axial direction are switched, and there is no need for any fine adjustment operation, which was the case with conventional screw-type systems.

[0070] Looking at Figures 1 to 12, a description has been given in the mode of embodiment depicted of a structure in which six counterbored holes 461 - 466 are formed at the rear side of the base part 452 of the rotational stopper 450 as "non-through holes (blind holes)", but two, or three or more counterbored holes may be provided. When a plurality of counterbored holes are formed, the respective counterbored holes may be provided equidistantly, taking the center axis of the rotational stopper 450 as a reference. Furthermore, a description has been given in the mode of embodiment depicted of a structure in which the counterbored holes 461 - 466 are formed in the base part 452 of the rotational stopper 450, but the counterbored holes may be provided in the rear body, and the rotational stopper positioning pins may be provided in the rotational stopper.

[0071] Furthermore, a description has been given in the mode of embodiment depicted of a structure in which provision is made for counterbored holes and rotational stopper positioning pins, but it would also be possible to position the rotational stopper in the axial direction using recesses provided on either the rotational stopper or the rear body, and projections provided on the other of the rotational stopper and the rear body. Furthermore, a description has been given in the mode of embodiment depicted of a structure in which the structural components are connected by screws or bolts, but keys, bayonets or any other well-known method may be used for the fixing method and connecting shapes.

[0072] The needle 150 is designed to come together with the front piston 170 and to be able to move in a forward/back direction along the center axis 114A of the nozzle. When the needle 150 moves back, the paint ejection orifice 122 can be opened by the front tip end of the needle 150. When the needle 150 moves forward, the paint ejection orifice 122 can be closed by the front tip end of the needle 150. As described above, when compressed air is not introduced into the front piston operating chamber 176, the front piston 170 moves forward and the needle tip 150C of the needle 150 is designed to close off the paint ejection orifice 122, under the elastic force of the needle spring 174.

[0073] The overall length of the needle 150 may be set at 66 mm, for example, and 10 mm of this may be designed to enter the front piston 170. The diameter of the needle 150 may be set at 4 mm, for example. The overall length when the needle 150 is fixedly attached to the front piston 170 may be set at 73.5 mm, for example. The tip end of the nozzle 114 and the tip end of the needle 150 should be flush.

[0074] By setting the dimensions in this way, it is possible to set the working parts of the two-stage pull by assembling the nozzle 114 of overall length 28 mm with the gun body 112 of overall length 60 mm, and using the needle 150 and front piston 170 of overall length 73.5 mm.

[0075] Looking at Figures 1 to 5, a gun paint passage 320 for the passage of paint is provided inside the gun unit 110 and the bracket unit 210. The gun paint passage 320 includes an outlet section 320A, a gun body-internal section 320B, a bracket unit-internal section 320C, and a bracket inlet section 320D. The outlet section 320A of the gun paint passage 320 is disposed between the inner wall of the nozzle 114 and the needle 150. The downstream side of the gun paint passage 320 is configured to form a passage with the paint ejection orifice 122.

[0076] Paint can be sent from the bracket inlet section 320D, which is the inlet end of the gun paint passage 320, toward the paint ejection orifice 122. With this configuration, the needle 150 constitutes a needle valve which is disposed in the gun paint passage 320. This means that the tip end of the needle valve is able to open and close the paint ejection orifice 122.

[0077] A paint return passage 324 for returning the paint is provided inside the gun unit 110. The paint return passage 324 includes a return port section 324A, a gun body-internal section 324B, a bracket unit-internal section 324C, and a bracket outlet section 324D. The outlet end 324D of the paint return passage and the bracket outlet section 324D of the gun paint passage 320 are disposed at the rear of the bracket unit 210.

[0078] An atomized air passage 330 for the passage of atomized air is provided inside the gun unit 110 and the bracket unit 210. The atomized air passage 330 includes an outlet section 330A, a gun body-internal section 330B, a bracket unit-internal section 330C, and a bracket inlet section 330D. The outlet section 330A of the atomized air passage 330 is disposed outside the outer wall of the nozzle 114. The downstream side of the atomized air passage 330 is configured to form a passage with a main atomized air orifice 125. Atomized air can be sent from the bracket inlet section 330D, which is the inlet end of the atomized air passage 330, toward the main atomized air orifice 125. Looking at Figure 3, the bracket inlet section 330D of the 23439

- 30 -

atomized air passage 330 is disposed at the rear of the bracket unit 210. In addition, the downstream side of the atomized air passage 330 may be configured to form a passage with an auxiliary atomized air orifice 124. This auxiliary atomized air orifice 124 has an auxiliary role, and it is also possible to employ a structure without this auxiliary atomized air orifice.

[0079] A pattern air passage 340 for the passage of pattern air is provided inside the gun unit 110. The pattern air passage 340 includes an outlet section 340A, a gun body- internal section 340B, a bracket unit-internal section 340C, and a bracket inlet section 330D. The outlet section 340A of the patt-" air passage 340 is disposed inside the inner wall of the retaining ring 128. The downstream side of the pattern air passage 340 is configured to form a passage with the pattern air hole 126. Pattern air can be sent from the inlet section 340D of the pattern air passage 340 toward the pattern air orifice 126. The inlet end 340D of the pattern air passage 340 is disposed to the rear of the bracket unit 210.

[0080] A front piston operating air passage 350 for the passage of operating air for ejecting paint, which causes the needle 150 to move back when paint is ejected, is provided inside the gun unit 110. The front piston operating air passage 350 includes a gun body-internal section 350B, a bracket unit-internal section 350C, and a bracket inlet section 350D. The downstream side of the front piston operating air passage 350 is designed to form a passage into the front piston operating chamber 176 which is provided in front of the front end of the front piston 170. Operating air can be sent from the inlet end of the front piston operating air passage 350 to the front piston operating chamber 176. With this configuration, the valve opening and closing device consists of a piston which is operated by means of front piston operating air sent from the front piston operating chamber 176. Looking at Figure 3, the inlet section 350D of the front piston operating air passage 350 is disposed to the rear of the bracket unit 210.

[0081] In addition, it is possible to allow the front piston 170 to move in a straight line backward along the center axis 114A of the nozzle by positioning the needle seal kit 160 as far as possible to the front. Furthermore, it is possible to improve the cleaning efficiency by making the color reservoir (volume of the flow passage) inside the gun body 112 as small as possible. In addition, it is possible to set a narrow gap between the nozzle 114 and the needle 150 by providing a tapered part at the rear of the nozzle 114, which makes it possible to carry out reliable cleaning and to improve the cleaning efficiency.

[0082] (3) Configuration of the bracket unit:

Looking at Figures 1 to 3, the bracket unit 210 includes a bracket main body 212 which constitutes the base member of the bracket unit. The bracket unit-internal section 320C and the bracket inlet section 320D of the gun paint passage 320 are provided in the bracket main body 212. The bracket unit 210 is detachably fixed to the gun body 112. The bracket inlet section 320D should consist of a straight thread, and an O-ring (preferably made of perfluoro) which is shaped like a counterbored hole should be disposed inside the thread. When the bracket unit 210 is fixed to the gun body 112, the paint and air received by the bracket unit 210 flows to the gun body 112.

[0083] The bracket unit-internal section 350C and the bracket inlet section 350D of the front piston operating air passage 350 for the passage of front piston operating air are provided in the bracket main body 212. A front piston operating air junction (not depicted) is provided in the inlet section 350D of the front piston operating air passage 350. The front piston operating air junction is linked to a control panel (not depicted) by way of a piping member such as a tube (not depicted) , and it may also be connected from the control panel to a front piston operating air supply source.

[0084] Operating air may be introduced from the inlet section 350D of the front piston operating air passage 350 to a spray device 100. When the bracket unit 210 is fixed to the gun unit 110, the inlet end of the gun body-internal section 350B of the front piston operating air passage 350 is connected to the outlet end of the bracket unit-internal section 350C. An 0-ring is preferably provided at this connection. An 0-ring may be provided on the bracket unit 210, it may be provided on the gun unit 110, or it may be provided on both. The inlet section 350D may consist of a tapered thread. An electromagnetic valve (not depicted) is provided in the front piston operating air passage 350. When the electromagnetic valve (not depicted) is open, front piston operating air introduced into the front piston operating chamber 176 can be discharged.

[0085] The bracket unit-internal section 330C and the bracket inlet section 330D of the atomized air passage 330 are provided in the bracket main body 212. An atomized air junction (not depicted) is provided in the inlet section 330D of the atomized air passage 330. The atomized air supply source and the atomized air junction may be linked using a piping member such as a connecting hose (not depicted) . The inlet section 330D should consist of a tapered thread. Operating air may be introduced into the spray device 100 from the inlet section 330D of the atomized air passage 330. When the bracket unit 210 is fixed to the gun unit 110, the inlet end of the gun body-internal section 330B of the atomized air passage 330 is connected to the outlet end of the bracket unit-internal section 330C. An O- ring is preferably provided at this connection. An O-ring may be provided on the bracket unit 210, it may be provided on the gun unit 110, or may be provided on both. [0086] The bracket unit-internal section 340C of the pattern air passage 340 and the bracket inlet section 330D are provided in the bracket main body 212. A pattern air junction (not depicted) is provided in the inlet section 340D of the pattern air passage 340. The pattern air supply source and the pattern air junction may be linked using a piping member such as a connecting hose (not depicted) . The inlet section 340D should consist of a tapered thread. Operating air may be introduced into the spray device 100 from the inlet section 340D of the pattern air passage 340. When the bracket unit 210 is fixed to the gun unit 110, the inlet end of the gun body-internal section 340B of the pattern air passage 340 is connected to the outlet end of the bracket unit-internal section 340C. An O-ring is preferably provided at this connection. An O-ring may be provided on the bracket unit 210, it may be provided on the gun unit 110, or may be provided on both.

[0087] The bracket unit-internal section 320C and the bracket inlet section 320D of the gun paint passage 320 are provided in the bracket main body 212. A paint inlet junction (not depicted) is provided in the bracket inlet section 320D of the gun paint passage 320. The bracket inlet section 320D should consist of a straight thread, and an O- ring (preferably made of perfluoro) which is shaped like a counterbored hole should be disposed inside the thread. The paint supply source and the paint inlet junction may be linked using a piping member such as a connecting hose (not depicted) . Paint can be introduced into the spray device 100 from the bracket inlet section 320D of the gun paint passage 320. When the bracket unit 210 is fixed to the gun unit 110, the inlet end of the gun body-internal section 320B of the gun paint passage 320 is connected to the outlet end of the bracket unit-internal section 320C. An O-ring is preferably provided at this connection. That is to say, when the bracket unit 210 is fixed to the gun unit 110, the paint received by the bracket unit 210 flows through the gun unit 110. An O-ring may be provided on the bracket unit 210, it may be provided on the gun unit 110, or may be provided on both.

[0088] The bracket unit-internal section 324C and the bracket outlet section 324D of the paint return passage 324 are provided in the bracket main body 212. A paint return port junction (not depicted) is provided in the bracket outlet section 324D of the paint return passage 324. The paint supply source (or the paint tank) and the paint return port junction may be linked using a piping member such as a connecting hose (not depicted) . Paint may be discharged from the bracket outlet section 324D of the paint return passage 324. The bracket outlet section 324D should consist of a straight thread, and an 0-ring (preferably made of perfluoro) which is shaped like a counterbored hole should be disposed inside the thread. When the bracket unit 210 is fixed to the gun unit 110, the outlet end of the gun body- internal section 324B of the paint return passage 324 is connected to the inlet end of the bracket unit-internal section 324C. An O-ring is preferably provided at this connection. An O-ring may be provided on the bracket unit 210, it may be provided on the gun unit 110, or may be provided on both.

[0089] In addition, looking at Figures 6 and 7, in order to respond to an air-type two-stage-pull spray device which will be described later, then during operation other than when the nozzle 114 is being cleaned, a rear piston operating air passage 360 may be provided for the passage of rear piston operating air which moves the rear piston further forward and holds it there. The rear piston operating air passage 360 includes a rear body-internal section 360A, a gun body-internal section 360B, a bracket unit-internal section 360C, and a bracket inlet section 360D. The downstream side of the rear piston operating air passage 360 forms a passage into a rear piston end chamber 186 which is provided to the rear of a rear piston main body 180B. Cleaning operation air can be sent from the inlet end of the rear piston operating air passage 360 to the rear piston end chamber 186.

[0090] The inlet section 360D of the rear piston operating air passage 360 is disposed to the rear of the bracket unit 210. When the rear body is fixed to the gun body 112, the inlet end of the rear body-internal section 360A of the front piston operating air passage 350 is connected to the outlet end of the gun body-internal section 360B. An 0-ring is preferably provided at this connection. An O-ring may be provided on the rear body, it may be provided on the gun body 112, or may be provided on both.

[0091] With the spray device according to the present invention, each of the abovementioned gun paint passage 320, paint return passage 324, atomized air passage 330, pattern air passage 340, front piston operating air passage 350, and rear piston operating air passage 360 may have an inner diameter which is set at a suitable value in the range from 2 mm to 10 mm. These inner diameters may be set to suitable values by simulation analyses, experimentation etc., talcing into account the viscosity of the atomized liguid and the state of atomization.

[0092] Looking at Figure 3, with the spray device according to the present invention, the bracket inlet section 320D of the gun paint passage 320, the bracket outlet section 324D of the paint return passage 324, the bracket inlet section 330D of the atomized air passage 330, the bracket inlet section 340D of the pattern air passage 340, the bracket inlet section 350D of the front piston operating air passage 350, and the bracket inlet section 360D of the rear piston operating air passage 360 are preferably provided on one surface of the bracket unit 210, for example a surface lying at the rear. Looking at Figure 1, the surface lying at the rear of the bracket unit 210 consists of three planes each at an angle. One or two or three of the bracket inlet section 320D of the gun paint passage 320, the bracket outlet section 324D of the paint return passage 324, the bracket inlet section 330D of the atomized air passage 330, the bracket inlet section 340D of the pattern air passage 340, the bracket inlet section 350D of the front piston operating air passage 350, and the bracket inlet section 360D of the rear piston operating air passage 360 may be disposed on each of these three planes. This configuration makes it possible for paint and air to be supplied rapidly and reliably to the spray device, and in a stable state. This configuration also means that the tubes for supplying paint and air are easily detached, so the tube detachment time can be shortened and the time of maintenance operations can be shortened.

[0093] When the spray device according to the present invention is used for liquids such as water, liquid-type adhesives, liquid-type rust prevention agents, liquid-type insulating agents, liquid-type coating agents and liquid- type drugs, the supply source for the liquid to be atomized and the paint inlet junction (that is to say, in such cases the junction which is configured as the "liquid inlet junction") may be linked using a piping member such as a connecting hose (not depicted) . The spray device according to the present invention has a unitary structure including the gun unit and the bracket unit, and therefore the production process for each structural component is simplified and the components can be easily assembled.

[0094] The spray device according to the present invention is configured as a plate-type gun. With this structure, the plate is fixed when the gun is mounted if the gun is fixed for use, if a robot is made to hold the gun, or if the gun is mounted on a reciprocating engine. When the gun undergoes maintenance, only the gun main body is detached, and overhauls can be carried out, parts can be replaced, or the main body can be replaced. This configuration makes it possible to avoid the problem of being unable to install the gun in its original position during installation after the 23439

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removal of a tube (hose) which occurs in conventional guns, which makes it possible to shorten the operating time.

[0095] A description has been given in this mode of embodiment and the figures depict a structure in which the gun unit is fixed to the bracket unit by a bolt with a hexagonal hole, but it is also feasible to use a one-touch (90° rotation) type structure.

[0096] (4) Coating operations using the spray device: Looking at Figure 1, the spray device 100 may be used in a fixed system, a robot may be made to hold an automatic spray gun for use, one or more automatic spray guns may be mounted on a device known as a "reciprocating engine" for use, or the above structures may be combined for use.

[0097] As the paint used in the spray device 100, it is possible to use solid paint, or it is possible to use metallic paint. Paint containing organic solvents may also be used. Paint containing aluminum powder may also be used. For example, the gun unit 110 of the spray device 100 is fixed to a robot arm. This fixing may employ a fastening member such as nuts or bolts. Alternatively, the gun unit 110 of the spray device 100 is fixed to a robot arm, after which the bracket unit 210 may be fixed to the gun unit 110. In this case, the bracket unit 210 is fixed to the gun unit 110, after which a connecting hose (not depicted) may be linked to the bracket unit 210, or the connecting hose is linked to the bracket unit 210 and then the bracket unit 210 may be fixed to the gun unit 110.

[0098] Looking at Figures 1 and 8, when coating operations are carried out, if the marks 430M on the adjustment knob 430 are set in a position corresponding to "1.5" from the marks 420M on the rear body 420, the rotational stopper positioning pins 432A, 432B enter the third counterbored hole 463 and the sixth counterbored hole 466. Furthermore, if the marks 430M on the adjustment knob 430 are set in a position corresponding to "2.0" from the marks 420M on the rear body 420, the rotational stopper positioning pins 432A, 432B enter the second counterbored hole 462 and the fifth counterbored hole 465.

[0099] Front piston operating air is introduced from the front piston operating air supply source into the front piston operating chamber 176, passing through the connecting hose and by way of the front piston operating air passage 350. When the front piston operating air is introduced into the front piston operating chamber 176, the needle 150 and the front piston 170 come together, and move backward along the center axis 114A of the nozzle in resistance to the spring force of the needle spring 174, and the cylindrical section lying at the rear of the front piston shaft 170A moves backward inside the inner peripheral part of the cylindrical section lying in front of the rotational stopper 450, and the end face at the tip end of the cylindrical section lying at the rear of the front piston shaft 170A is maintained in a state of contact with the step part inside the inner peripheral part of the cylindrical section lying in front of the rotational stopper 450. For the front piston operating air, it is possible to use compressed air at around 0.25 MPa to 0.35 MPa, for example. The amount by which the needle 150 can move backward may be set at 2 mm, for example.

[0100] When the needle 150 moves back, the paint ejection orifice 122 opens. Paint is supplied, from the paint supply source by way of the piping member such as a connecting hose, from the gun paint passage 320 to the nozzle 114, and paint can be ejected from the paint ejection orifice 122.

[0101] At this point, atomized air is introduced from the atomized air supply source through the connecting hose, by way of the atomized air passage 330, and passes through the main atomized air orifice 125 (and if necessary through the auxiliary atomized air orifice 124), and atomized air is ejected so that it is possible to atomize the paint ejected from the paint ejection orifice 122. The atomized air used may be compressed air at around 0.25 MPa, for example. The atomized state of the paint can be adjusted by changing the atomized air pressure and the number and arrangement of auxiliary atomized air orifices 124.

[0102] Furthermore, pattern air is introduced at the same time from the pattern air supply source through the connecting hose, by way of the pattern air passage 340, and the pattern air is ejected from the pattern air orifice 126, whereby a pattern of atomized paint can be formed. The pattern air used may be compressed air at around 0.25 MPa, for example. The shape of the paint pattern can be adjusted by changing the pattern air pressure and the number and arrangement of pattern air orifices 126.

[0103] The paint which is discharged from the tip end of the nozzle 114 is normally atomized by the atomized air in the air cap 120, and the paint is formed into a fan-shape by the pattern air. If the needle 150 is not positioned in the center of the nozzle 114, the discharge state of the paint which is discharged from the tip end of the nozzle 114 is unstable. In the present invention, as described above, it is possible to allow the front piston 170 to move in a straight line backward along the center axis 114A of the nozzle by positioning the needle seal kit 160 as far as possible to the front. Furthermore, in the present invention, as will be described later, the rear piston main body 180B and a needle stopper 180C of the rear piston 180 which is disposed at the rear serve to receive the front piston 170, and the rear piston 180 itself is reliably placed on the center axis 114A of the nozzle by means of a rear coupling 172 and a rear body 190, and the front piston 170 can be moved in a straight line backward along the center axis 114A of the nozzle. The configuration of the present invention therefore makes it possible for the needle 150 to be positioned at the center of the nozzle 114, and for the rear piston 180 to be moved in a straight line backward along the center axis 114A of the nozzle, and therefore it is possible to improve the durability to wear of the needle 150 and the sliding components inside the needle seal kit 160.

[0104] The remaining paint which is not ejected from the paint ejection orifice 122 can be returned to the paint supply source (or the paint tank) via the paint return passage 324 and the connecting hose. By doing so, it is possible to construct a paint circulation line. Alternatively, various kinds of liquids, including water, adhesives, rust prevention agents, insulating agents, coating agents and drugs can be automatically or manually atomized using the spray device according to the present invention.

[0105] When the coating operation has been completed, the supply of front piston operating air is stopped, and the needle 150 and front piston 170 come together and are moved forward by the spring force of the needle spring 174. When the needle 150 moves forward, the paint ejection orifice 122 closes, and the ejection of paint from the paint ejection orifice 122 can be stopped. At the same time, the supply of atomized air can be stopped, and the supply of pattern air can be stopped.

[0106] (5) Cleaning of the nozzle:

Looking at Figures 1 and 8, when the nozzle of the spray gun body is cleaned, the marks 430M on the adjustment knob 430 are set in a position corresponding to "CLEAN" of the marks 420M on the rear body 420. In this state, the rotational stopper positioning pins 432A, 432B enter the first counterbored hole 461 and the fourth counterbored hole 464. When the nozzle of the spray gun body is cleaned, the gun unit 110 of the spray device 100 is removed from the robot arm so that the nozzle 114 can be cleaned. Alternatively, the nozzle 114 can be cleaned with the gun unit 110 of the spray device 100 still attached to the robot arm.

[0107] Looking at Figure 13, in a state in which front piston operating air has been introduced into the front piston operating chamber 176 from the front piston operating air supply source, the needle 150 and the front piston 170 come together, and they are maintained in a state in which they move backward along the center axis 114A of the nozzle, in resistance to the spring force of the needle spring 174. At this point, the amount by which the needle 150 can move back may be set at 3 mm, for example . By virtue of this configuration, the amount by which the needle 150 can move back from the closed state of the nozzle 114 to the nozzle cleaning state may therefore be set at 5 mm, for example.

[0108] As described above, the degree of opening of the discharge port of the spray device according to the present invention can be set in a total of three different positions, namely two coating positions and one position for cleaning, and improved performance can be achieved in terms of significantly reduced cleaning times and significantly improved operating efficiency. Furthermore, with the spray device according to the present invention, the needle position can be manually set to fully open by operation of the adjustment knob. Furthermore, when the needle position is returned to the original position, the needle position can be manually set so as to return to the original position by operation of the adjustment knob. Furthermore, with the spray device according to the present invention, the needle position during coating is always a fixed position, which means that there is an effect whereby the quality of the object to be coated (product) can be kept constant. Furthermore, the spray device according to the present invention has a detachable unitary structure, and therefore the components making up each of the units can be easily produced and assembled. [0109] (6) Air-type two-stage-pull spray device:

(6-1) Closed nozzle state

A description will be given below of the configuration and action when an air-type two-stage-pull spray device is constructed using the gun unit according to the present invention. Looking at Figure 16, the rear coupling 172 is disposed to the rear of the gun body 112. The needle spring 174 is provided in order to push the front piston main body 170B forward. The rear section of the needle spring 174 is disposed so as to come into contact with the planar section facing the front of the rear coupling 172. The front section of the needle spring 174 is disposed so as to come into contact with a section facing the rear of the front piston flange 170F of the front piston main body 170B. The center axis of the needle spring 174 may lie on the center axis 114A of the nozzle. The front piston 170 is subjected to force in a forward-moving direction by means of the elastic force of the needle spring 174. Accordingly, when compressed air is not introduced into the front piston operating chamber 176, the front piston 170 moves forward and the needle tip 150C of the needle 150 is designed to close off the paint ejection orifice 122.

[0110] The rear body 190 is fixed to the rear of the gun body 112 by means of the fixing bolts 192. The rear body 190 can be fixed to the gun body 112 using two rear body fixing bolts 192, for example. The rear coupling 172 is disposed inside the rear body 190. The rear body 190 is preferably formed from POM (polyoxymethylene) , for example.

[0111] Looking at Figure 16, the gun unit 110 is provided with the rear piston 180 which can move along the center axis 114A of the nozzle. The rear piston 180 is disposed at the rear of the front piston 170, inside the rear body 190. The rear piston 180 includes a rear piston main body 180B and a rear piston shaft part 180G. A rear piston hole 180H is provided inside part of the rear piston shaft part 180G from the front of the rear piston main body 180B. The needle stopper 180C is fixed in the rear piston hole 180H. A rear piston 0-ring 180D is disposed inside a groove at the outer periphery of the rear piston main body 180B. The center axis of the rear piston 180 lies on the center axis 114A of the nozzle. The outer peripheral part of the cylindrical section lying at the rear of the front piston shaft 170A is slidably disposed within the inner peripheral part of the cylindrical section lying in front of the needle stopper 180C. The outer peripheral part of the cylindrical section lying at the rear of the needle stopper 180C is fixed inside the inner peripheral part of a hole lying in front of the rear piston main body 180B. The planar section facing the front of the rear piston main body 180B is disposed so as to come into contact with the planar section facing the rear of the rear coupling 172.

[0112] The rear piston end chamber 186 for receiving the rear piston operating air which moves the rear piston 180 forward along the center axis 114A of the nozzle is configured inside the rear body 190, behind the rear piston main body 180B. In addition, a rear piston operating chamber 188 for the introduction of rear piston operating air which has been received in the rear piston end chamber 186 in order to push the rear wall surface of the rear piston main body 180B is configured inside the rear body 190, outside the shaft part behind the rear piston main body 180B.

[0113] The rear piston 0-ring 180D is disposed in a groove provided at the outer periphery of the rear piston main body 180B. The rear piston O-ring 180D is provided in order to seal the rear piston main body 180B and the rear body 190. As regards the rear piston O-ring 180D, it is preferable to use an O-ring in order to increase the sliding resistance for receiving the front piston 170. The rear piston O-ring 180D is preferably formed from perfluoro.

[0114] The rear piston main body 180B may be formed from aluminum alloy A2021 (alumite treatment may be carried out, for example) . The outer diameter of the front piston 170 is preferably designed to be smaller than the outer diameter of the rear piston 180. Accordingly, the outer diameter of the front piston seal 170C is preferably designed to be smaller than the outer diameter of the rear piston 0-ring 180D.

[0115] The needle 150 is designed to come together with the front piston 170 and to be able to move in a forward/back direction along the center axis 114A of the nozzle. When the needle 150 moves back, the paint ejection orifice 122 can be opened by the front tip end of the needle 150. When the needle 150 moves forward, the paint ejection orifice 122 can be closed by the front tip end of the needle 150. In addition, the needle 150, front piston 170 and rear piston 180 are designed to come together and to be able to move further back along the center axis 114A of the nozzle from the position in which the needle 150 has moved back together with the front piston 170.

[0116] The overall length of the needle 150 may be set at 66 mm, for example, and 10 mm of this may be designed to enter the front piston 170. The diameter of the needle 150 may be set at 4 mm, for example. The overall length when the needle 150 is fixedly attached to the front piston 170 may be set at 73.5 mm, for example. The tip end of the nozzle 114 and the tip end of the needle 150 should be flush.

[0117] By setting the dimensions in this way, it is possible to set a one-stage pull of 2 mm, for example, by assembling the nozzle 114 of overall length 28 mm with the gun body 112 of overall length 60 mm, and using the needle 150 and front piston 170 of overall length 73.5 mm, and by adjusting the rear coupling 172 of width 4 mm, the dimensions of the rear piston 180, and the hole depth of the needle stopper 180C inside the rear piston main body 180B of overall length 26 mm. Furthermore, it is possible to set the working parts of a two-stage pull of 3 mm, for example, by adjusting the dimensions inside the rear body 190, the rear coupling 172 of width 4 mm, and the dimensions of the working parts of the rear piston 180.

[0118] The inner diameter of the cylinder of the front piston 170 is 22 mm, for example. The inner diameter of the cylinder of the rear piston 180 is 24 mm, for example.

[0119] A rear piston operating air passage (not depicted) for the passage of rear piston operating air which moves the rear piston 180 further forward and holds it there during operations other than when the nozzle 114 is being cleaned is provided inside the rear body 190. The downstream side of the rear piston operating air passage is configured to form a passage into the rear piston end chamber 186 which is provided at the rear of the rear piston main body 180B. Cleaning operation air can be sent from the inlet end of the rear piston operating air passage to the rear piston end chamber 186.

[0120] The inlet section of the rear piston operating air passage is disposed behind the bracket unit 210. When the rear body 190 is fixed to the gun body 112, the inlet end of the rear body-internal section of the front piston operating air passage is designed to be connected to the outlet end of the gun body-internal section. An 0-ring is preferably provided at this connection. An 0-ring may be provided on the rear body 190, it may be provided on the gun body 112, or it may be provided on both.

[0121] Looking at Figure 16, the rear body 190 has two bolt holes for the passage of the rear body fixing bolts. The rear body 190 also has six air passage holes 190K which form a passage between the rear piston end chamber 186 and the rear piston operating chamber 188. A plurality of air passage holes 190K are preferably arranged concentrically with the center axis 114A of the nozzle at the center. Six air passage holes 190K are shown, but there may be four air passage holes, or eight air passage holes, or another number of such holes. The plurality of air passage holes are preferably concentrically disposed such that there is an equal angular interval therebetween with the center axis 114A of the nozzle at the center. By providing this concentric plurality of air passage holes 190K, the rear piston 180 can move reliably and smoothly forward.

[0122] The rear piston main body 180B and the needle stopper 180C of the rear piston 180 which is disposed at the rear serve to receive the front piston 170, and the rear piston 180 itself is reliably placed on the center axis 114A of the nozzle by means of the rear coupling 172 and the rear body 190. This configuration makes it possible for the front piston 170 to be moved in a straight line backward along the center axis 114A of the nozzle. In addition, the configuration of the present invention makes it possible for the rear piston 180 to be moved in a straight line backward along the center axis 114A of the nozzle.

[0123] (6-2) First open state of the nozzle

Looking at Figure 17, rear piston operating air is introduced from the rear piston operating air supply source into the rear piston end chamber 186, passing through the connecting hose, and by way of the rear piston operating air passage. The rear piston operating air which is introduced into the rear piston end chamber 186 passes through the plurality of air passage holes 190K and flows into the rear piston operating chamber 188 from the rear piston end chamber 186. When the rear piston operating air is introduced into the rear piston operating chamber 188, the rear piston 180 moves forward along the center axis 114A of the nozzle, and the planar section facing the front of the rear piston main body 180B is maintained in a state of contact with the planar section facing the rear of the rear coupling 172. For the rear piston operating air, it is possible to use compressed air at around 0.4 MPa to 0.5 MPa, for example . [0124] Front piston operating air is introduced from the front piston operating air supply source into the front piston operating chamber 176, passing through the connecting hose and by way of the front piston operating air passage 350. When the front piston operating air is introduced into the front piston operating chamber 176, the needle 150 and the front piston 170 come together, and move backward along the center axis 114A of the nozzle in resistance to the spring force of the needle spring 174, and the cylindrical section lying at the rear of the front piston shaft 170A moves backward inside the inner peripheral part of the cylindrical section lying in front of the needle stopper 180C, and the end face at the tip end of the cylindrical section lying at the rear of the front piston shaft 170A is maintained in a state of contact with the step part inside the inner peripheral part of the cylindrical section lying in front of the needle stopper 180C.

[0125] For the front piston operating air, it is possible to use compressed air at around 0.25 MPa to 0.35 MPa, for example. The rear piston operating air pressure is set to be higher than the front piston operating air pressure. The difference between the rear piston operating air pressure and the front piston operating air pressure may be set at around 0.05 MPa to 0.25 MPa, for example. The amount by which the needle 150 can move backward may be set at 2 mm, for example.

[0126] When the needle 150 moves back, the paint ejection orifice 122 opens. Paint is supplied, from the paint supply source by way of the piping member such as a connecting hose, from the gun paint passage 320 to the nozzle 114, and paint can be ejected from the paint ejection orifice 122.

[0127] At this point, atomized air is introduced from the atomized air supply source through the connecting hose, by way of the atomized air passage 330, and passes through the main atomized air orifice 125 (and if necessary through the 23439

- 48 -

auxiliary atomized air orifice 124), and atomized air is ejected so that it is possible to atomize the paint ejected from the paint ejection orifice 122. The atomized air used may be compressed air at around 0.25 MPa, for example. The atomized state of the paint can be adjusted by changing the atomized air pressure and the number and arrangement of auxiliary atomized air orifices 124.

[0128] Furthermore, pattern air is introduced at the same time from the pattern air supply source through the connecting hose, by way of the pattern air passage 340, and the pattern air is ejected from the pattern air orifice 126, whereby a pattern of atomized paint can be formed. The pattern air used may be compressed air at around 0.25 MPa, for example. The shape of the paint pattern can be adjusted by changing the pattern air pressure and the number and arrangement of pattern air orifices 126.

[0129] (6-3) Second open state of the nozzle (nozzle cleaning state)

A description will be given below of the action when the nozzle of the spray gun body is cleaned. Looking at Figure 18, in a state in which front piston operating air has been introduced into the front piston operating chamber 176 from the front piston operating air supply source, an electromagnetic valve (not depicted) which is provided in the rear piston operating air passage is opened, whereby the rear piston operating air which has been introduced into the rear piston end chamber 186 and the rear piston operating chamber 188 is discharged.

[0130] By means of this, the needle 150, front piston 170, and rear piston 180 come together and move backward along the center axis 114A of the nozzle in resistance to the spring force of the needle spring 174, and the planar section facing the rear of the rear piston main body 180B is maintained in a state of contact with the step part inside the rear body. At this point, the amount by which the needle 150 can move back may be set at 3 mm, for example. By virtue of this configuration, the amount by which the needle 150 can move back from the closed state of the nozzle 114 to the nozzle cleaning state may therefore be set at 5 mm, for example.

[INDUSTRIAL APPLICABILITY]

[0131] The spray device described above can be easily realized with any of the three types of conventional spray devices, namely adjust type, air-type two-stage-pull type and manual multiple-stage type spray devices. That is to say, it is possible to increase the value of the objects to be coated (products) by means of a synergistic effect achieved by using three types of spray device, making it possible to achieve a distinction with standard products. In addition, with a manual multiple-stage type spray device according to the present invention, there is one less air circuit than with an air-type two-stage-pull type spray device (the same as with a conventional adjust type spray device) , and therefore there is the advantage that when a conventional adjust type spray device is being used, it is possible to replace this with a manual multiple-stage type spray device according to the present invention without adding an air circuit. Furthermore, the spray device according to the present invention has a detachable unitary structure, and therefore it is simple to produce and assemble each of the components making up the unit.

[0132] The spray device according to the present invention can also be used in a fixed system; it can also be used in a system in which a robot is made to hold an automatic spray gun; it can be used in a system in which one or more automatic spray guns are mounted on a device known as a "reciprocating engine"; or it may be used in a system combining the above configurations. The spray device according to the present invention makes it possible to shorten the downtime when the spray gun body is cleaned, when the spray gun body is replaced, or when the nozzle is replaced, and paint can be sprayed with only a short amount of time lost. Furthermore, the spray device according to the present invention makes it possible to shorten the downtime for coating operations when the nozzle is cleaned. In addition, the spray device according to the present invention makes it possible to spray not only paint but also various kinds of liquids, including water, adhesives, rust prevention agents, insulating agents, coating agents and drugs. The structural components of the spray device according to the present invention can be easily produced and assembled, and therefore the device can be produced using a simple process.

[KEY TO SYMBOLS]

[0133]

100 spray device

110 gun unit

112 gun body

114 nozzle

150 needle

160 needle seal kit

170 front piston

174 needle spring

176 front piston operating chamber 180 rear piston

186 rear piston end chamber

188 rear piston operating chamber

190 rear body

210 bracket unit

220 bolt with hexagonal hole

400 spray device

420 rear body

430 adjustment knob

450 rotational stopper

Claims

SCOPE OF THE PATENT CLAIMS

[Claim 1]

A spray device for spraying paint from a paint ejection orifice, which is provided with: a nozzle having a paint ejection orifice for atomizing and ejecting paint; a needle for opening and closing the paint ejection orifice; a front piston which is fixed to the needle; a needle spring which is provided so as to push the front piston toward the paint ejection orifice; a gun body which accommodates the nozzle and accommodates the front piston; a rear body which is disposed to the rear of the gun body; a needle position adjustment mechanism for adjusting the position of the needle in a direction along the center axis of the nozzle; and a bracket unit which is detachably fixed to the gun body; when the bracket unit is fixed to the gun body, the paint and air contained in the bracket unit flow through the gun body, the needle position adjustment mechanism includes an adjustment member which is rotatable with the center axis of the nozzle at the center, and a rotation position setting member for setting the position of the front piston along the center axis of the nozzle in correspondence to the angle of rotation of the adjustment member, and the needle position adjustment mechanism is adjusted so that when the front piston moves together with the needle along the center axis of the nozzle in a direction away from the paint ejection orifice in a state in which the amount of discharge paint exiting the paint ejection orifice has been set, the front piston and the needle come together and move in a direction away from the paint ejection orifice.

[ Claim 2 ]

The spray device as claimed in claim 1, wherein the needle position adjustment mechanism includes an adjustment knob which is rotatable with the center axis of the nozzle at the center, and a rotational stopper for setting the position of the front piston along the center axis of the nozzle in correspondence to the angle of rotation of the adjustment member; and the outer peripheral part of the cylindrical section of the front piston is slidably disposed within the inner peripheral part of the cylindrical section of the rotational stopper.

[Claim 3]

The spray device as claimed in claim 2, wherein a plurality of counterbored holes are formed in the rotational stopper, and a rotational stopper positioning pin is provided in the rear body; and the rotational stopper positioning pin can be positioned in the counterbored holes by moving the adjustment knob in the direction along the center axis of the nozzle and causing the rotation of the adjustment knob.