US3637135A

US3637135A - Method of and apparatus for spray coating components

Info

Publication number: US3637135A
Application number: US819216A
Authority: US
Inventors: Manfred H Luderer; Anton Ettenhofer
Original assignee: Atlas Copco AB
Current assignee: Atlas Copco AB
Priority date: 1968-04-26
Filing date: 1969-04-25
Publication date: 1972-01-25
Anticipated expiration: 1989-01-25
Also published as: JPS5037224B1; GB1271731A; NL6906440A; AT301723B; BE732185A; FR2007075A1; CH505653A

Abstract

An arrangement for spray coating components with a dry material, such as powder, or a wet material, such as paint, includes a removable and replaceable supply container for the material in which the material is circulated and is supplied to a feeding trough through a regulatable discharge opening. Within the container and the feeding trough the material is selectively vibrated and then delivered to an injector where compressed air is added and the mixture of compressed air and material is conveyed through a closed passageway to a spray gun equipped with high-voltage electrodes at its outlet. The arrangement includes a control panel for selecting the voltage and polarity at the spray gun outlet and for regulating the vibration effect and the supply of air provided to the apparatus.

Description

ie States Pate lLnderer at al.

[ 1 Jan. 23, 1972 [54] METHOD OF AND APPARATUS FQR SPRAY CGATING COMPONENTS [72] Inventors: 'Manfred H. Luderer, Weiler Zum Stein; Anton Ettenhofer, Winnenden, both of Germany 3,327,948 6/1967 Gignoux ..239/15 X 3,432,079 3/1969 Williams...

2,779,510 l/l957 Wilson et al.

2,900,138 8/1959 Strate 3,029,000 4/1962 Kobee....

3,065,032 1 H1962 Sylvester... ..302/56 3,097,828 7/1963 Grun ..222/95 X 3,355,222 ll/l967 Neely ..302/56 Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-John J. Love [5 7] ABSTRACT An arrangement for spray coating components with a dry material, such as powder, or a wet material, such as paint, includes a removable and replaceable supply container for the material in which the material is circulated and is supplied to a feeding trough through a regulatable discharge opening. Within the container and the feeding trough the material is selectively vibrated and then delivered to an injector where compressed air is added and the mixture of compressed air and material is conveyed through a closed passageway to a spray gun equipped with high-voltage electrodes at its outlet. The arrangement includes a control panel for selecting the voltage and polarity at the spray gun outlet and for regulating the vibration effect and the supply of air provided to the apparatus.

16 Claims, 9 Drawing Figures PATENIED JANZS I972 ATTORNEY;

METHOD OF AND APPARATUS FOR SPRAY COATING COMPONENTS powder or for wet coating.

The plant serves above all for applying powder to components, but by quick conversion it can equally well be used for applying paint by the wet process, in which airless paint spraying or air-operated paint spraying may be used.

Compared to the plants known in prior art, the plant ac cording to the present invention uses a new process for applying powder to components having in tripartition new process steps and their combinations. The process steps are broadly divided into a feeding process, a setting and switching-in process, and a changeover and cleaning process. The individual process steps differ from the known plants in that they provide much faster changeover from one color to another and also better cleaning of the plant. Accordingly, an object of the invention is to provide a plant pennitting, in the application of powder to components, easy changing of the filling funnel and using the filling funnel without the application of pressure.

Another object is to design the filling funnel as exchangeable, the requirement being that the filling funnel can be taken out without the powder contained therein flowing out.

Another object is to provide the possibility of changing over the plant from one color component to another as quickly as possible without involving complicated time-consuming disassembly and cleaning work at the plant as was the case with the conventional plants.

A still further object is to provide the possibility of effecting regulation of the powder quantity and adjustment of the powder cloud in front of the gun clearly and quickly.

A still further object of the invention is to provide the possibility of changing the polarity of the applied high voltage in the electrostatic field from positive to negative from the material side, in accordance with the different types of powder without requiring conversion of the plant.

Another object of the plant is to secure during operation, when switching on and off the plant at the gun, that a powder flow is built up quickly and that the powder flow is interrupted instantaneously without powder afterflow taking place.

A further object of the invention is to design the plant for universal application by providing the possibility to not only spray powder, but to also spray paint onto components by the wet-coating process, for which the electrostatic section of the plant is to be used.

The invention complex is divided into process steps which are of respective importance for the employment of the whole plant and into a part which describes the appliances per mitting the process steps.

The invention solves the problem by comprising in groups the individual process steps for the feeding process, setting and switching in process, and changeover and cleaning process, and stating the typical process steps for the respective group.

The feeding process is governed by circulating powder in the powder funnel in a rotary motion and by having vibrations act upon the powder funnel in a vertical direction. This provides an effective rotary circulation and breaking up of the powder in the powder funnel so that conglomeration of the powder cannot take place.

The excitation of the powder funnel in vertical direction by vibrations provides further breaking up of the powder in the powder funnel. In the process a powder funnel is used which is open on top. Application of pressure is not provided for in this process.

According to the process, vibrations .act on the feeding trough in horizontal direction, an application of vibrations in vertical direction also being provided for by special measures. This results in uniform powder feeding in the feeding trough, also eliminating conglomerations of powder.

Vibrations act on the air injector in vertical direction, so that a uniform feeding of powder-air mixture into the supply hose to the gun is secured.

These process steps for the feeding process result in uniform powder feeding from the powder funnel to the gun outlet.

The second group of the process for applying powder comprises the process steps providing the setting and switching in process according to the application. The powder funnel is opened when it is put onto the appliance in the powder delivery, i.e., the powder funnel can be removed and in removed condition is closed on the bottom at the powder outlet. This provides easy exchange of the powder funnel and thus easy changing from one powder to another, for example in different colors.

Moreover, a process step is provided, alternatively permitting to lock the powder funnel at different heights relative to the feeding trough. The advantage of this is that the powder quantity can be preset, which is necessary for various types of powder.

The air supply for the circulation in the powder funnel is antomatically coupled when this is being attached.

The powder quantity is set by means of voltage regulation of the horizontal vibrator at the feeding trough. Furthermore the air quantity for the injector is regulated by means of a control valve in the airline.

The voltage of the high-voltage generator, after depressing a test key, is set at a voltage regulator with indication at a voltmeter, the high-voltage supply cable and the electrodes at the gun being kept clear from voltage. This has the great advantage that safe regulation of the magnitude of the high voltage at the electrode is possible.

Corresponding to feeding of different powders it is possible to select the polarity of the high voltage at the electrode of the gun at a triple-pole switch with the settings plus-zero-minus.

Switching on the device is effected by means of a compressed air valve at the gun and a compressed air switch in the device, with the cascade for the high voltage switched on, the horizontal and vertical vibrators switched on, and the compressed air supply to the injector being open, the venting devices in the line between the compressed air supply valve and the gun outlet being shut off. This has the great advantage that it makes possible a quick switching on and generation of a powder current and quick interruption of the powder current without afterflow when switching off the gun.

The third group of the process claims of the application covers the changeover and cleaning processes which are necessary in order to be able to changeover the plant from one type of powder to another type of powder.

According to the process, the powder funnel is lifted off the device, cutoff of the powder flow and of the air supply being released automatically. It may then either be refilled or it can be exchanged with another powder funnel filled with another powder.

In a further process step the injector is removed from the holder and emptied. Moreover the feeding trough can be dedusted by switching on the horizontal vibrator and subsequently the injector and the hose can be dedusted by means of the gun, for example by feeding an air current into the injector.

For putting into operation it is then only necessary to set up a filled powder funnel and to lock it, whereupon the plant is again fully ready for operation.

From what has been disclosed above it can be seen that by the process steps according to the invention the plant provides a reliable feeding process for the powder and at the same time gives simple and clear setting and switching in processes, completely excluding faulty operation of the plant.

Furthermore the process steps according to the invention clearly provide the simple changeover and cleaning process at the plant which has not existed with the plants known in prior art.

In a further modification of the plant according to the invention also other combinations of the process steps can be applied resulting likewise in plants which are very useful in practice. It is, for example, possible to carry out the process without rotary circulation of the powder in the powder funnel.

Further, the powder and air quantity can be commonly set by means of coupled setting members. This possibility results in a further simplification of the control of the plant.

Furthermore, in accordance with the invention the changeover and cleaning process can be combined with the material supply steps without the setting and switching steps.

In a further modification of the invention a combination of the process steps covering the feeding, changeover and cleaning can be combined with certain steps of the setting and switching in process and this partial combination, too, provides an element which is typical for one part of the plant according to the invention.

The individual process steps according to the invention are of special importance for the total function of the plant, so that it is necessary to emphasize them as individual characteristics.

All of these steps involved in the process have not been applied before and have not yet become known in prior art. Prepossessions of experts were partly the reason why these process steps have not been applied in this combination or the significance of the process steps in their combination had not been realized, this being reserved to this invention.

The aforesaid process steps can according to the invention be accomplished by the appliances mentioned in the following. According to the invention an air injection body, for example in the form of a sintering body is arranged in the powder funnel in the range of the centerline, whose blowout surface produces an air current directed upwardly, in such a way that a nearly revolving motion of the powder particles directed from bottom to top is produced.

It is possible to use a closed sintering body which is of ringshaped design. But single sintering bodies which have the same effect can be arranged just as well.

This appliance has the great advantage that the powder current for breaking up the powder in the funnel results in a continuous circulation of the powder. Appliances known in prior art were so arranged that they acted against one another.

For realizing the process according to the application, an appliance is suggested stating the mount of the powder funnel and the associated parts. The mount of the powder funnel, of the feeding trough, and of the air injector is combined to a compact part. This is so designed that a support chassis acted upon by the vertical vibrator carries directly coupled a supporting carrier for the powder funnel and the injector, while the feeding trough acted upon in its longitudinal centerline by a horizontal vibrator, is coupled to the support chassis through rubber cushions and the compact part is connected to the appliance chassis through rubber cushions. This mount arrange ment provides the great advantage that on the one hand a horizontal motion in the feeding trough takes place for the powder and on the other hand also a vertical motion in the powder funnel in the direction of feeding towards the feeding trough and in the injector in the direction towards the hose connection to the gun. This compact block is one of the most essential construction features of the entire plant.

Moreover the appliance according to the invention is so designed that the powder funnel is exchangeable and that it is provided with an appliance which automatically opens and closes, respectively, the powder outlet when attachment and removal is accomplished, thus eliminating loss of powder. This permits at the same time easy removal of the powder funnel. The powder funnel can be filled outside the plant or a different powder funnel with a different powder can be attached.

Moreover, catches are provided at the powder funnel which, individually selectable, permit adjustment of the vertical outlet distance relative to the feeding trough. In this way a preselection of the outlet opening to the feeding trough can be made.

This exchangeability of the powder funnel is an essential feature of the application, as it is possible with one manipulation to remove the powder funnel, for example for refilling.

In this way contamination of the entire plant by powder is eliminated.

When the powder funnel is being attached, the powder out let is automatically opened or closed. This may be accomplished, for example, by dogs or rollers running against cams. It is advisable to shut 011' the powder in the funnel by means of a butterfly valve or other slide valve elements.

Moreover, when attachment is accomplished, at the same time an air connection device is provided serving for air admission to the air injection bodies in the powder funnel.

Adjustment of the powder quantity fed to the gun is also possible by adjusting the supply voltage to the horizontal vibrator of the feeding trough. In this way two adjusting means are provided regulating the quantity of powder fed to the gun.

The adjusting means for the supply voltage of the horizontal vibrator and the air valve for the injector can be directly coupled or coupled through gear members.

In this way a further simplification of the adjustment of the appliance is obtained. Coupling can be effected by means of a through shaft or alternatively gear members such as cams, dogs, differentials, or the like, can be arranged between the operating shafts. In this way functionally different adjusting processes between the shafts can be realized.

The appliance according to the invention permits switching over of the high-voltage cascade by a central switch in the control desk, switching to positive-zero-negative being possible, so that also the high-voltage potential at the electrode of the gun has this polarity.

The changeover switch for the polarity is arranged in cascade and goes through various cascade stages, the polarity of the respective switching elements being changed in every stage.

In rnidposition zero of this changeover switch the capacitors are discharged.

The appliance according to the invention reveals a further essential improvement over the conventional plants in that when switching off the air supply for the injector at least one vent valve is actuated at the same time which reduces the pressure in the direction to the gun.

This has the great advantage that immediately after switching off at the front of the gun, discharge of powder-gas mixture is eliminated and afterflow does not occur.

The vent valve can be installed between the shutofi valve and the injector. However, it is just as well possible to install a further vent valve between injector and gun. Furthermore there is also the possibility to install two vent valves, each at the above described spots.

The appliance according to the invention is switched on by actuating a compressed air switch seated in the gun actuating in the device a compressed-air-operated switch which operates the cascade, the vibrators, and the compressed air valve for the injector.

In this way it is possible to use a gun which needs no lines other than the high-voltage cable. t

A special advantage of the appliance according to the application is that the injector is arranged in a quick-action clamping holder at the support chassis, this holder for example permitting removal of the injector after unlocking a lever. In this way provision is made for quick cleaning of the injector and thus also for quick changeover of the plant, for example, from one color to another.

A special test key in the control panel permits on the one hand switching off of the high voltage from the gun and discharge of the electrode at the gun. On the other hand, however, regulation of the high voltage for the electrostatic field can be obtained at a KV-calibrated indicating instrument in the primary circuit. Adjustment is effected by an adjusting regulator, for example a regulating transformer in the primary circuit. After releasing the test key the high-voltage value set is applied to the electrodes of the gun.

The appliance according to the invention is so designed that on the one hand the powder current adjustable at the control desk is acted upon by air in the injector and on the other hand a further airline supplies to the gun accelerating air which is also adjustable at the control desk.

In this way easy and reliable breaking up of the powder in the injector can be obtained and at the same time also sufficient acceleration of the broken up powder current at the gun can he achieved so that the powder current impinges on the component with sufficient acceleration energy.

In a further modification of the appliance according to the invention connections and valves are arranged at the appliance permitting alternatively the connection of wet spraying devices, airless or air-operated devices, in such a way that in the case of airless operation a respective compressed air paint pressure converter with respective airless gun can be applied or a compressed-air-operated gun can be applied, in such a way that also the high-voltage connection for additional electrostatic spraying can be fully used in the device.

This universal applicability offers the plant according to the invention a further field of service and for smaller enterprises the possibility of operating according to different processes. This provides the advantage that the plant achieves a much greater performance and is longer in operation as the various possibilities eliminate downtimes.

The basic study of the plant according to the invention provides with the influence on the powder current in the various active components further very important combination features which are of importance for employing the plant. They fall into four large groups:

As to I, influencing the powder quantity by an adjustable distance between the powder funnel and the feeding trough and by an adjustable voltage at the horizontal vibrator of the feeding trough As to 2, premixing and feeding to the gun by an adjustable air current at the injector.

As to 3 atomizing degree and acceleration at the gun outlet by an adjustable accelerating air current direct to the gun and a high-voltage field adjustable in voltage of selectable polarity between the electrodes and component being coated.

As to 4, cloud shape of the powder cloud in front of the gun by baffle and guide bodies in front of the gun outlet. This combination of characteristics for influencing the powder current in the various active components of the powder is a very important total characteristic of the plant according to the invention which in the former combination has not yet been found in any plant.

Another feature involves the reduction of pressure when switching off the powder current of the gun in the line between the control valve of the compressed air and injector and gun. This provides the great advantage that, when switching off, afterflow of powder does not occur.

In a further modification of the invention it has now been found that in the case of specifically relatively light powders the following process steps are sufficient for the process:

la. Powder is fed into a powder funnel as a storage container and gets via a b. discharge socket at the powder funnel into an c. injector.

The entire vibrating facility can be dispensed with. It is, however, necessary for frit or heavy ceramic powders.

In a further modification of the invention it may be proceeded in such a way that the process consists of the process steps 2a-c, whereby:

2a. Powder is fed into a powder funnel as a storage container and gets via a b. discharge socket at the powder funnel into a c. cellular-wheel lock whose upper cells take the powder from the funnel and whose lower ones are used as blowing de ice.

The powder is fluidized with airat least in one process step to la, lb, 1c; 2a, 2b, 2c.

The expression fluidized as used here means that sintering bodies which are porous are within the powder rooms. Into these sintering bodies air is lead from outside, the air being directed via the sintering bodies on a larger surface into the powder.

The air supply for fiuidizing is separately controllable in at least one process step. This means that there is the possibility that all process steps are separately controllable for fluidizing. It is, however, also possible to proceed in such a way that certain groups are combined and operated by one control.

In a further development of the invention the delivery of the powder-air mixture at the gun is variable in quantity. Variations can be effected either continuously or according to a function.

The appliance for carrying through the process is so designed that at least part of the walls getting in contact with powder are equipped with fluidizing bodies.

It can be proceeded in such a way that, for example, in the powder funnel a ball-shaped fluidizing body is arranged effect ing some kind of circulation of the powder in the funnel.

The air supply for the groups of fluidizing bodies belonging together may be separately adjustable at the device.

In a further modification of the invention the appliance can be so designed that a cellular-wheel lock with several chambers is used which is arranged directly underneath the powder funnel in such a way that the chambers facing the funnel collect the powder from the funnel and that delivery air acts upon at least one lower chamber in axial direction, subject to the condition that in the wall side an injector is arranged in outgoing direction, to which injector the feed hose to the powder gun is connected.

The appliance which has the injector arranged directly underneath the powder funnel, has the advantage that the plant is of relatively simple design.

It can be proceeded in such a way that the plant as a whole according to the invention is designed with all vibrating equipment which can be switched off and that the injector can be attached directly underneath the powder funnel.

In this way a plant is obtained which is suitable for spraying relatively specifically light and specifically heavy powders such as frit or ceramic powder.

At least part of the walls getting in contact with powder are coated with plastic materials of the group of the polytetrafluoroethylene or plastic materials of the group of the copolymers from tetrafluoroethylene, hexafluoropropylene or the like. It can also be proceeded in such a way that these parts are made right of these plastic materials.

It is also possible to use generally fluorinated and/or siliconated plastic materials for this purpose.

In a further development of the invention the trigger at the handle of the gun for the discharge of the powder-air mixture in the range of the first length of path is designed in such a way that it actuates a valve for smaller quantity, at the rear stop a valve for full quantity. In this way the powder-air current can be regulated and thus with the smaller quantity, for example, grooves or pipe sections requiring a smaller quantity can be treated and on the other hand when depressing the trigger to its full extent large surfaces can immediately be coated with powder.

It is, however, also possible that the trigger actuates a valve for continuously and/or functionally increasing powder-air delivery providing the advantage that a powder quantity continuously increasing in quantity or increasing according to a certain function can be released by the operator.

Separate lines may lead from the device to the valves in the gun, the lines being separately adjustable in the device. In this way the gun can easily be adapted to the various situations without unnecessary spraying of powder.

The means of solution of the invention are schematically represented in the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. ll shows a general diagrammatic view of the principle of the plant, to explain the process,

FIG. 2 shows a view of the entire device with spray gun, in perspective representation,

FIG. 3 illustrates a device according to the application with opened front section where the injector can be seen,

FIG. 4 shows a diagrammatic circuit diagram of the valves of the venting appliance,

FIG. 5 shows a diagrammatic partial representation as a side view of an appliance which has the injector arranged directly underneath the powder funnel,

FIG. 6 illustrates an appliance which has a cellular-wheel lock arranged underneath the'powder funnel, shown as sectional diagrammatic side view,

FIG. 7 is a diagrammatic view of an appliance according to FIG. 6 in longitudinal section on line II-II,

FIG. 8 shows an appliance according to the invention in diagrammatic line representation, with the arrangement of the fluidizing bodies,

FIG. 9 shows a circuit diagram of the regulation of the powder-air mixture at the device and at the gun.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a general view which serves to explain the individual process steps.

Rubber cushions 2 carrying a support chassis 3 are mounted to the appliance chassis 1. At the support chassis 3 again rubber cushions 4 are arranged carrying, through supports 5, the feeding trough 6. Permanently attached to the support chassis 3 is the injector 15 and the funnel 11 which contains the powder 48. The funnel 11 is set at the support chassis 3 and, through the catches 14, only two being shown as an example, can be arrested in height as desired relative to the feeding trough 6.

In the powder funnel 1 1 an air-injection body 12 is arranged which is designated as ring-shaped body in the example. This air-injection body is automatically coupled to an air supply line at 13 when being inserted. The directions of the arrows in the powder funnel 11 indicate the direction of circulation of the powder 48 so that this is broken up in the powder funnel l 1.

At the powder funnel 11 a butterfly valve 9 is arranged which via coupling members is connected to a roller and a dog, for example, opening the butterfly valve 9 when inserting the funnel from above and closing the butterfly valve 9 automatically, when taking out, so that no powder will get out of the powder funnel any longer.

The powder 48 flows on to the feeding trough 6 which is arranged slightly inclined towards the injector 15. At the support chassis 3 a vertical vibrator 8 of the usual design is arranged which is supplied with current through a connection 20. By means of this vibrator the support chassis 3 is caused to vibrate with the funnel in horizontal direction. At the same time this vibrator is coupled to the trough 6 through the rubber cushions 4.

At the feeding trough 6 a horizontal vibrator 7 is arranged which is supplied with current through connection 19. In the supply line an adjusting device 16 is provided at which the voltage for the horizontal vibrator 7 can be set.

The injector is supplied with compressed air from line 18 which can be regulated in quantity in the adjusting device 17. In the injector 15 the compressed air accelerates the powder that has come in and carries it through hose 26 to the spray gun 32. From the line 25 the spray gun 32 is additionally supplied with an accelerating air which can be set in the adjusting device 52.

At the spray gun 32 a handle 30 is arranged which carries an air valve 31, at which all electrical switching operations can be controlled through a compressed air blast. Serving this purpose is a compressed air switch 23 whose electrical part is connected to the mains at 24 and whose control input 53 is connected to the

inputs

20, 21, 19 of the electric driving elements.

This has the advantage that no further control lines need be arranged to the spray gun 32.

The high voltage is generated in the high-voltage generator 36, for example in a cascade and carried through the high voltage cable 29 to the electrodes 33 at the spray gun 32. It is also evident from FIG. 1, how the powder current 35 gets to the workpiece 34. The high voltage is caused to leave the cascade 36 at 37.

At the cascade 36 a switch 40 for changing the polarity is arranged making it possible to draw high voltage of positive or negative polarity. The voltage can be regulated in the primary circuit by means of the adjusting device 39. The test key 38 serves for regulating the high voltage which can be indicated at the device 41 as shown in FIG. 2. The function of the test key and adjustment of the high voltage is described in more detail elsewhere.

FIG. 2 shows a front view, in perspective representation oblique from above, of the entire device with the powder spray gun 32 which is suspended from a stand 51. It can be recognized that the powder funnel 11 is inserted in the housing at the top side while the control knobs are arranged on the front side.

The voltage for the horizontal vibrator 7 can be set at the adjusting device 16. The quantity of compressed air for the injector 15 can be set at the adjusting regulator 17. Both adjusting

devices

16 and 17 can be coupled as shown by the dotted line 54 in FIG. 1. In this connection it is possible that gear members are arranged between the adjusting devices.

The accelerating air can be set at the adjusting device 52. Pressure gauges for the pressure indication are arranged behind the adjusting

devices

17 and 52.

The solenoid valve for the accelerating air can be switched on and off at switch 42 (FIG. 2), while the air supply for the air to the injector can be switched on and off at switch 43.

The high voltage is switched on and off at switch 51. The test key is denoted by 38.

After inserting the powder funnel 11 and turning into the proper position, and at the same time opening the butterfly valve 9 and accomplishing the respective locking at 14, the powder funnel 11 can be arrested by a lever 55.

After being disengaged, the powder funnel can be taken out of the housing upwardly.

FIG. 3 is a front view, oblique from above, of a device with the front door 45 being opened so that the injector 15 is visible. The injector 15 is arranged on the support chassis 3 and can easily be removed and cleaned after unlocking lever 44. The discharge hose 26 leads to the spray gun 32.

A water trap 46 is incorporated in the air supply line to the injector 15. The latter is explained in more detail in FIG. 4. The feeding trough 6 can also be seen behind the injector 15. After depressing the test key 38 the high voltage can be adjusted in its value at the adjusting regulator 39 and reading can be taken from the instrument at 41.

The remaining controls and parts are denoted by the same reference figures as in FIGS. 1 and 2.

FIG. 4 is a general circuit diagram in schematic representation in which from connection 18 compressed air is supplied to the solenoid valve 42 which switches on and off the air current to the injector l5. In-between is the water trap 46. From FIG. 4 it can also be seen how powder 48 flows from the feeding trough 6 into the injector 15 and by the supplied compressed air is supplied to line 26 which carries it as powder mixture to the powder spraying gun 2. From FIG. 4 it is also evident that the solenoid valve 42 when being closed opens a bypass valve 47, by means of which the pressure buildup in the direction of hose 26 and to the injector 15 is abruptly reduced so that spraying of powder-air mixture is abruptly stopped at the powder spraying gun 32. A valve 49 can also be arranged in line 26, there being the possibility to couple the

valve

47 and 49 and to reduce the pressure in both pipe sections.

An advantage of the device according to the application is that the high-voltage supply, the proportioning appliance, and the powder storage container are accommodated in a desklike sheet-steel casing. In devices known in prior art the control desk and the powder container with its chassis are separately arranged.

A further advantage is that the high-voltage supply is designed for either negative polarity, positive polarity or reconnectable for both polarities. There is no need for replugging the high-voltage cable when changing the polarity.

In a plant known in the art two different high-voltage cascades are installed for changing the polarity which are then alternatively coupled respectively. In the present plant according to the application only one high-voltage cascade is provided for.

Moreover, it is very useful that charging the large opening of the powder funnel is relatively easy and that the powder funnel can be exchanged as a whole. It is also an advantage that the powder funnel is kept pressureless so that it is always easy to check from above whether there is still sufiicient powder in the powder funnel. The ball catch of the powder funnel permits easy adjustment of the distance from the feeding trough so that continuous powder quantity adjustment is secured. Also the fully filled powder funnel can be easily exchanged, this being very useful for cleaning or for changing the color. The proportioning appliance is also accommodated in the casing and permits extremely fine regulation of the throughout quantities over a relatively wide range of regulation. Afterspraying of the material being charged, with other plants encountered in practice when, completely the working process and the delay of the material flow when taking up work is largely eliminated by the design of the feeding trough with a horizontal and vertical vibrator. Moreover, vent valves ensure that afterspraying stops immediately when switching off at the spray gun.

The plant can be used for alternate operation for powder spraying and wet coating which is of special advantage to smaller enterprises. The regulation of the powder quantity and the air pressure can also be of such design that the

switching devices

62 and 43 are designed as step switches and that the adjusting

devices

17 and 52 are designed as fine pressure regulators.

At the device also an air blowout gun for cleaning the containers and the like can be connected to the airline.

In FIG. a modification of the invention is represented, in which the injector 61 is arranged directly underneath the feed hopper 55.

As described in the main arrangement and as can be seen from FIG. 9, the powder air current is fed from the injector 61 to the spray gun. The injector is fastened to the chassis by means of a thumb screw 63.

In the present modification the powder funnel 55 and also the injector 61 do not require vibration energy.

In a further development of the invention it can be proceeded in such a way that the plant described is the main arrangement is equipped with a vibration drive, but also permits removal of the vibration drive with a few manipulations and placing of the injector 6ll directly underneath the powder funnel 55 and to thus operate the plant without vibration drive. This will be applicable especially in the case of specifically relatively light types of powder. In the case of relatively heavy types of powder, however, the vibration drive and the feeding trough will be applied.

It is evident from FIG. 5 how the butterfly valve shaft 57 which can close the powder funnel at the bottom, is automatically movable through a lever 58 and a check track 59 when the powder funnel 55 is removed from its bajonet catch by turning.

The advantage of the present invention is that an alternatively individually adaptable plant for spraying all types of powder has been developed which can be fully used in practice for various fields of service without requiring different models ofplants.

A further modification of an appliance is illustrated in FIG. 6, in which underneath the powder funnel 64 a cellular-wheel lock 65 is arranged taking out powder from the powder funnel 6 6 by means of the cellular wheel 66 through an opening 43 and, when rotating, delivering it towards the lower section to opening 70, as indicated by the direction of the arrow. At its blade ends the cellular wheel is provided with brush devices 67 for the purpose of closing the individual cellular chambers.

Moreover, as shown in FIG. 7, the cellular wheel is driven by a motor 66 in the direction of the arrow. In the lower section an air inlet 72 is provided which, for example, feeds air into the chamber 73 and blows the powder contained therein by the injector 70 into the pipeline 74 which is connected with the powder gun. In this way a certain quantity of powder is supplied to the powder gun through line 741 in dependence on the speed of the motor 66 and the size of the slot 63'.

In order to provide a pressure balance in the direction towards the filling slot 63', at the left-hand side as shown in FIG. 6 a pressure balance opening 711 is provided in addition which may, for example, be connected to the fluidizing bodies 69.

It is evident from FIG. 7 how in the direction of the arrow 76' the powder gate from the powder funnel 66 through the opening 63 into the upper section of the cellularwheel lock 65.

It is also evident from FIG. 7 how the cellular-wheel lock 65 is combined with the injector 70.

FIG. 8 is a diagrammatic line representation of an appliance according to the invention where it can be recognized in what manner the fluidizing bodies 69 can be arranged in the powder funnel 66. Moreover fluidizing bodies 76 are arranged in the discharge socket and fluidizing bodies 78 in the injector 77. It is evident from FIG. 8 that the fluidizing body 69 can be supplied with air by an adjusting vale 79 and the fluidizing body 76 by adjusting valve 80 and fluidizing body 78 by adjusting valve 61 so that optionally a certain fluidizing effect may be set by selection of the air pressure. At the lower section of the injector 77 the mixing chamber 611 can be seen, into which compressed air flows in the direction of the arrow 98 and powder-air mixture flows out through the opening 62 in the direction of the arrow, the powder-air mixture being fed through a hose to the powder spraying gun.

With the embodiment described it is achieved that on its way from the funnel to the spray gun the powder is broken up in the various stations and an agglomeration of powder at the points of deflection is eliminated.

FIG. 9 illustrates a diagrammatic representation of a circuit diagram of the regulation of the powder-air mixture at the device and at the gun.

When serving the trigger 82, which is arranged at the gun, a short distance in the direction of the arrow 63, the valve 84 is actuated and through line 86 a compressed-air switch 37 is actuated which opens the solenoid valve 89 and thus a smaller quantity of compressed air withdrawn from the line 86 through a pressure-reducing valve 92 and proportioned through a check valve 93 is fed to the injector 95 withdrawing powder from the powder funnel 6d and feeding powder-air mixture to the line 96 which leads to the powder gun. With this appliance in the first stage only relatively little compressed air and thus also powder is fed to the powder gun so that smaller projections or lugs at the objects to be coated can easily be coated with powder without larger powder quantities getting lost.

If the trigger 82 at the powder gun is further depressed in the direction of the arrow 83, valve is opened and the compressed-air switch 86 actuates the solenoid valve 90, whereby a larger quantity of compressed air is fed from the pressurereducing valve 911 through the check valve 96 to the injector so that the maximum performance regarding the powder weight of the spray gun is obtainable.

It can be recognized that this appliance permits relatively uncomplicated a quick adaptation of the powder quantity fed to the requirements of the design of the workpieces to be coated.

It is possible to coat at least part of the walls getting into contact with powder, with fiuorinated and/or siliconated plastic materials of the respective groups or to make these parts from such plastic materials. The walls concerned are the walls of the powder funnel or of the discharge socket of the powder funnel or also the walls of the injector and the cellular Wheel lock, respectively. It is advisable to design also the powder hose between injector and powder gun in the same manner.

In this way it is secured that the powder does not, due to its adhesion, stick to the walls it gets in contact with and does not form agglomerations.

FIG. 7 is a diagrammatic view of a spray gun 100 with extended gun tube 101 and baffle body 102 with high-voltage electrodes 103.

We claim:

1. Process for spray coating a material in powdered or liquid form on components, comprising inserting a vessel, having a closed discharge opening and which contains the material to be spray coated, into a supply station responsive to such insertion, opening the discharge opening from the vessel and coupling a supply of air to the vessel for circulating the material within the vessel, discharging the material within the vessel from the discharge opening to a conveyor member for transport to an injection station, injecting compressed air into the material in the injection station, feeding the mixture of material and compressed air to an outlet station, and providing a high voltage at selectable polarity at the outlet station.

2. Process, as set forth in claim 1, characterized by, at the completion of the spray coating, removing the vessel and, responsive to such removal, interrupting flow of material from the vessel and supply of air into the vessel.

3. Process, as set forth in claim 1, characterized by vibrating the material between the vessel and the injection station.

4. Process, as set forth in claim 3, characterized by directing the air into the vessel for imparting a rotary motion to the material circulated within the vessel.

5. Process, as set forth in claim 1, characterized by selectively varying the spacing between the discharge opening from the vessel and the conveying member.

6. Process, as set forth in claim 3, characterized by vibrating the vessel containing the material in the vertical direction.

7. Process, as set forth in claim 3, characterized by vibrating the conveying member in the horizontal and the vertical directions.

8. Process, as set forth in claim 3, characterized by vibrating the material into which the compressed air in injected in the vertical direction.

9. Process, as set forth in claim 1, characterized by providing a closed passageway for feeding the materials and compressed air from the injection station to the outlet station.

10. Process, as set forth in claim 7, characterized by adjusting the quantity of material conveyed on the conveying member by varying the voltage regulation of the vibration of the conveying member.

11. Process, as set forth in claim 1, characterized by adjustably varying the quantity of air injected into the material at the injection station.

12. Process, as set forth in claim 1, characterized by adjustably setting the voltage at the outlet station.

13. Process, as set forth in claim 12, characterized by selectively varying the polarity of the high voltage at the outlet station between plus-zero-minus.

14. Process, as set forth in claim 1, characterized by variably regulating the flow of the materials and compressed air for controlling the flow from the outlet station.

15. Process, as set forth in claim 2, characterized by unloading the supply of material from the injection station.

16. Process, as set forth in claim 15, characterized by dedusting the conveying member, the injection station, and the closed passageway from the injection station to the outlet station after completing the spraying of the material.

Claims

2. Process, as set forth in claim 1, characterized by, at the completion of the spray coating, removing the vessel and, responsive to such removal, interrupting flow of material from the vessel and supply of air into the vessel.
3. ProCess, as set forth in claim 1, characterized by vibrating the material between the vessel and the injection station.
4. Process, as set forth in claim 3, characterized by directing the air into the vessel for imparting a rotary motion to the material circulated within the vessel.
5. Process, as set forth in claim 1, characterized by selectively varying the spacing between the discharge opening from the vessel and the conveying member.
6. Process, as set forth in claim 3, characterized by vibrating the vessel containing the material in the vertical direction.
7. Process, as set forth in claim 3, characterized by vibrating the conveying member in the horizontal and the vertical directions.
8. Process, as set forth in claim 3, characterized by vibrating the material into which the compressed air is injected in the vertical direction.
9. Process, as set forth in claim 1, characterized by providing a closed passageway for feeding the materials and compressed air from the injection station to the outlet station.
10. Process, as set forth in claim 7, characterized by adjusting the quantity of material conveyed on the conveying member by varying the voltage regulation of the vibration of the conveying member.
11. Process, as set forth in claim 1, characterized by adjustably varying the quantity of air injected into the material at the injection station.
12. Process, as set forth in claim 1, characterized by adjustably setting the voltage at the outlet station.
13. Process, as set forth in claim 12, characterized by selectively varying the polarity of the high voltage at the outlet station between plus-zero-minus.
14. Process, as set forth in claim 1, characterized by variably regulating the flow of the materials and compressed air for controlling the flow from the outlet station.
15. Process, as set forth in claim 2, characterized by unloading the supply of material from the injection station.
16. Process, as set forth in claim 15, characterized by dedusting the conveying member, the injection station, and the closed passageway from the injection station to the outlet station after completing the spraying of the material.