CN116133773A

CN116133773A - Injection device for die casting machine and casting method

Info

Publication number: CN116133773A
Application number: CN202180060609.6A
Authority: CN
Inventors: 村上工成; 石桥直树; 釼祐一郎; 宫本悠生; 栋久贵司
Original assignee: Ube Machinery Corp Ltd
Current assignee: Ube Machinery Corp Ltd
Priority date: 2020-09-29
Filing date: 2021-05-31
Publication date: 2023-05-16
Also published as: WO2022070507A1; JP2022055677A

Abstract

The invention provides an injection device of a die casting machine and a casting method, which can prevent external air from flowing into a sucked sleeve, thereby inhibiting molten metal from being disturbed or molten metal in advance. The injection device (10) is provided with a sleeve (11) and a plunger (20). The plunger (20) is provided with a punch (21) and a rod (22). The sleeve (11) is provided with more than 2 suction ports (101, 102) penetrating the sleeve (11) in the inside and outside and arranged along the front-rear direction (D1). The plunger (20) comprises: a punch body (201) including at least a front end of the punch (21); a suction recess (203) which is retracted radially inward relative to the inner peripheral part of the sleeve (11) at a position behind the punch body (201); a punch rear part (202) protruding radially outward from the suction recess (203), the suction recess (203) being divided from the rear side; and a rear suction path (204) which communicates with the suction recess (203) from a position rearward of the punch rear (202).

Description

Injection device for die casting machine and casting method

Technical Field

The present invention relates to an injection device for injecting molten metal into a cavity of a die casting machine by a plunger that can advance and retreat inside a sleeve, and a casting method by die casting.

Background

In order to efficiently increase the vacuum level of a cavity in which molten metal is supplied to a sleeve or from which molten metal is injected by a plunger, and to suppress occurrence of blowholes in a die-casting product, a technique of sucking the inside of the sleeve is known.

For example, patent document 1 describes a die casting machine that sucks the inside of a sleeve using a vacuum suction device.

The die casting machine is provided with first to fourth suction devices for sucking the inner side of the sleeve and the cavity of the die. The first suction means and the second suction means are used in suction on the inside of the sleeve. The first suction device sucks the inside of the sleeve through the opening penetrating the sleeve at a position in front of the pouring opening into which the molten metal such as aluminum alloy is poured. The second suction device sucks the inside of the sleeve from a position on the rear side of the plunger punch through a suction tube connected to a through hole penetrating the flange provided in the plunger rod in the axial direction. The through hole of the flange communicates with a closed space formed between a constricted portion, which is between the rear end of the plunger punch and the flange, and the inner peripheral surface of the sleeve. According to patent document 1, by sucking the closed space by the second suction device, the space in front of the punch is sucked through the gap between the outer peripheral surface of the punch and the inner peripheral surface of the sleeve.

According to patent document 1, after molten metal is injected into a sleeve, when a plunger is advanced to a position where a pouring port is closed by a plunger punch, first, gas in a space in the sleeve in front of the punch is sucked by a first suction device through an opening of the sleeve. At this time, the gas of the cavity is also sucked through the space in front of the inside of the sleeve.

When the plunger is advanced to a position where the opening of the sleeve is closed by the punch, suction is started from the rear of the punch to the front of the punch by the second suction device through the closed space at the position of the neck portion and the gap between the punch and the sleeve. When the plunger is advanced to a position where the opening of the sleeve is closed by the flange at the rear of the punch, the direct suction to the cavity is started by the third suction device. In addition, the fourth suction means is for sucking an inner space of the base supporting the movable mold.

According to the disclosure of patent document 1, the first suction device and the second suction device are used in combination to increase the vacuum degree in the sleeve, so that the occurrence of the air holes can be suppressed. Further, since the direct suction to the cavity is started after the opening of the sleeve is closed, the vacuum degree in the cavity can be prevented from being higher than the vacuum degree in the sleeve, and the generation of the preceding molten metal (preceding molten metal) can be suppressed from being sucked into the cavity before injection.

Prior art literature

Patent literature

Patent document 1: japanese patent No. 5987674

Disclosure of Invention

Problems to be solved by the invention

When the external air flows into the sleeve which is negative in pressure with respect to the atmospheric pressure by suction, and the molten metal in the sleeve is disturbed, there are cases where: the suction opening is blocked by the adhesion of the molten metal droplets, or the suction efficiency is lowered by the accumulation of the molten metal components (molten metal slag) in the vacuum line. Further, there is a concern that the molten metal is disturbed to generate a blowhole.

The term "turbulence of the molten metal" means, for example, foaming and scattering of the molten metal or severe shaking of the liquid surface due to the blowing of external air from the rear end of the sleeve through a radial gap between the plunger and the sleeve to the front of the punch.

In patent document 1, in order to efficiently vacuumize the inside of the sleeve and the cavity, the inside of the sleeve is depressurized at one time by making the suction of the first suction device higher in suction efficiency than the second suction device precede the suction of the second suction device. The pressure difference between the space in front of the punch and the outside air applied at this time causes the outside air to flow in, and therefore, the molten metal is disturbed.

In patent document 1, the suction by the first suction device and the suction by the second suction device are stopped at predetermined timings, respectively, but during the period of stopping the suction in the sleeve, the external air flows into a position in front of the punch, and the molten metal is disturbed.

As described above, an object of the present invention is to provide an injection device and a casting method for a die casting machine, which can prevent external air from flowing into a sucked sleeve, thereby suppressing turbulence of molten metal or preceding molten metal.

Means for solving the problems

The present invention is an injection device provided with: a sleeve, the inner side of which is supplied with molten metal; and a plunger that can advance and retreat in the front-rear direction inside the sleeve, and by which the injection device injects molten metal into a cavity of the die casting machine.

The plunger is provided with: a punch for extruding molten metal in the sleeve forward; and a rod supporting the punch from the rear.

The sleeve is provided with more than 2 suction ports penetrating the sleeve through the inner side and the outer side and arranged along the front-rear direction.

The plunger includes: a punch body including at least a front end of the punch; a suction recess which is retracted radially inward with respect to the inner peripheral portion of the sleeve at a position rearward of the punch body; a punch rear portion protruding radially outward from the suction recess, the punch rear portion defining the suction recess from the rear side; and a rear suction path communicating with the suction recess from a position rearward of the rear portion of the punch.

An injection device for a die casting machine of the present invention comprises: a sleeve, the inner side of which is supplied with molten metal; and a plunger that can advance and retreat in the front-rear direction inside the sleeve, and by which the injection device injects molten metal into a cavity of the die casting machine.

The sleeve is provided with 1 suction port or more than 2 suction ports arranged along the front-rear direction, and the suction ports penetrate the sleeve in an inner side and an outer side.

The injection device is provided with a control unit configured to control the operation of a suction system capable of sucking through 1 or more suction ports and a rear suction path, respectively.

The control unit starts suction from the suction recess through at least one of the suction port and the rear suction path after the gate of the sleeve is closed by the rear part of the punch according to the position of the plunger or the elapsed time from the start of injection by the plunger, starts suction from the front space, which is a space forward of the punch body, through the suction port after starting suction from the suction recess, and continues suction from the suction recess through the rear suction path before the suction port furthest forward from the gate of more than 1 suction ports is closed by the rear part of the punch, or continues suction from the suction port until the suction is stopped, at least until the plunger reaches a switching position for switching from speed control to pressure control.

In the injection device for a die casting machine according to the present invention, the control unit continues to suck from the suction recess through the rear suction path until the filling of the molten metal into the cavity is completed.

For example, if a signal indicating that the plunger has reached the speed-pressure switching position near the plunger position at the time of completion of filling is generated, suction from the suction recess through the rear suction path can be stopped by closing the valve corresponding to the rear suction path. This makes it possible to substantially continue the suction from the suction recess until the completion of the filling.

Alternatively, after the plunger reaches the speed-pressure switching position, for example, if it is detected that filling has been completed based on the casting pressure, the valve corresponding to the rear suction path is closed, whereby suction from the suction recess can also be continued until filling is completed.

In the injection device of the die casting machine of the invention, the sleeve is provided with more than 2 suction ports arranged along the front-back direction, and if the projection area of the suction ports projected to the suction concave part is A ₁ The projection area of the rear suction path projected to the suction concave part is A ₂ Then A ₂ Can be set to A which periodically changes relative to the position of the plunger ₁ Is above the lower limit of (2).

A ₁ Corresponds to the projection area of the suction port when projected from the direction orthogonal to the axial direction of the sleeve to the suction concave portion. A is that ₂ Corresponds to the projected area of the rear suction path when projected from the axial direction of the sleeve to the suction concave portion.

The present invention is a casting method including an injection and filling step of injecting and filling molten metal into a cavity of a die casting machine by a plunger that can advance and retreat in a front-rear direction inside a sleeve to which molten metal is supplied, the plunger including: a punch for extruding molten metal in the sleeve toward the front; and a rod for supporting the punch from the rear, the sleeve having 1 or more than 2 suction ports arranged in the front-rear direction, the suction ports penetrating the sleeve through the inside and the outside, the plunger comprising: a punch body including at least a front end of the punch; a suction recess which is retracted radially inward with respect to the inner peripheral portion of the sleeve at a position rearward of the punch body; a punch rear portion protruding radially outward from the suction recess, the punch rear portion defining the suction recess from the rear side; and a rear suction path communicating with the suction recess from a position rearward of the rear portion of the punch.

The injection filling process includes the following steps depending on the position of the plunger or the elapsed time from the start of injection by the plunger: a first step of starting suction from the suction recess through at least one of the suction port and the rear suction path after the pouring port of the sleeve is closed by the rear portion of the punch; a second step of starting suction from a space in front of the punch body through the suction port after starting suction from the suction recess; a third step of starting suction from the suction concave part through the rear suction path before the suction port farthest from the pouring port to the front of more than 1 suction ports is closed by the rear part of the punch and stopping suction, or continuously performing suction from the suction port until the suction is stopped; and a fourth step of continuing suction from the suction recess through the rear suction path at least until the plunger reaches a switching position at which the speed control is switched to the pressure control.

In the fourth step of the casting method of the present invention, it is preferable that the suction from the suction recess is continued through the rear suction path until the filling of the molten metal into the cavity is completed.

Therefore, for example, if a signal indicating that the plunger has reached the speed-pressure switching position is generated, the valve corresponding to the rear suction path may be closed, or if it is detected that filling has been completed based on the casting pressure, the valve corresponding to the rear suction path may be closed, thereby stopping suction from the suction recess through the rear suction path.

In the casting method of the present invention, it is preferable that suction from the suction recess is continuously performed in a front-rear direction of a position where the suction port farthest forward from the pouring port passes through the rear portion of the punch and stops the suction, so that a pressure difference smaller than a pressure difference between the front space and the suction recess is continuously applied to the front space and the outside air.

In the casting method of the present invention, the injection filling step preferably includes: a low-speed injection step of moving the plunger at a relatively low speed; and a high-speed injection step of moving the plunger at a relatively high speed, wherein in the low-speed injection step, the movement of the plunger is temporarily stopped or decelerated, and suction is performed from the suction recess through at least one of the suction port and the rear suction path throughout the front and rear of the stop or deceleration of the plunger.

Effects of the invention

According to the present invention, by the displacement of the plunger with respect to the sleeve, the suction port of the sleeve is closed by the punch, and thus, even if the vacuum suction from the suction recess through the suction port is interrupted, the vacuum suction from the suction recess through the rear suction path can be continued from the rear of the suction recess. Accordingly, since the reduced pressure space can be continuously provided in the suction recess located behind the space located in front of the punch, the inflow of the external air into the space in front of the punch due to the pressure difference can be prevented until the final stage of the injection and filling process, and the turbulence of the molten metal and the generation of the preceding molten metal can be suppressed. By preventing inflow of external air, clogging of a path for suction can be suppressed, so that vacuum suction can be performed stably and efficiently, and thus, it is also possible to contribute to stabilization of quality of a cast product and improvement of productivity.

Drawings

Fig. 1 is a partially cut-away side view showing an injection device according to an embodiment of the present invention and a die casting machine provided with the injection device.

Fig. 2 is a schematic view showing a vacuum suction system provided in the die casting machine shown in fig. 1.

Fig. 3 is a view showing a sleeve and a plunger tip of the injection device shown in fig. 1.

Fig. 4 (a) and (b) are graphs showing changes in the plunger speed (solid line) and casting pressure (broken line) in the injection filling step and the pressurizing and holding step.

Fig. 5 (a) is a diagram showing a state in which the projection area of the suction port projected to the suction concave portion is maximized. (b) The drawing shows a state in which the projection area of the suction port projected to the suction concave portion is minimized. (c) The drawing shows a state in which one of the suction ports is opened to the atmosphere.

Fig. 6 is a graph showing that the projected area of the suction port projected to the suction recess varies according to the position of the plunger (injection stroke).

Fig. 7 is a view for explaining an injection filling process, and (a) shows the plunger in a home position. (b) The position of the plunger is shown after the gate is closed by the rear of the punch and vacuum suction within the sleeve is initiated. (c) The suction port (# 1) closest to the gate is shown in a state of being closed by the rear of the punch.

Fig. 8 is a view showing the plunger (c) in fig. 7, which proceeds in the order of (a) to (c). In (b), the suction port (# 2) farthest from the pouring port is closed by the punch rear portion.

Fig. 9 (a) shows the plunger being moved toward the speed-pressure switching position X while continuing to suck from the suction recess _VP Forward progress. (b) Showing the plunger reaching the speed-pressure switching position X _VP Is a state of (2). (c) shows the plunger returned to its original position.

Fig. 10 is a partially cut-away side view showing an injection device according to a modification of the present invention and a die casting machine provided with the injection device. Only 1 suction port is formed in the sleeve.

Fig. 11 (a) shows a state in which the gate is closed by the rear portion of the punch and suction can be started through the suction port and the rear suction path, respectively. (b) The suction port is closed and suction is continued only through the rear suction path.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(outline structure of die casting machine)

The structure of the die casting machine 1 will be briefly described with reference to fig. 1 to 3.

The die casting machine 1 includes: a movable tray 3 provided with a movable die 2 and a product pushing mechanism 2A; a fixed plate 5 provided with a fixed die 4; a base 6 for supporting the movable plate 3 and the fixed plate 5; a mold opening/closing mechanism not shown; an injection device 10 provided in the fixed plate 5 and injecting molten metal toward the cavity 7; a vacuum pumping system 30 (fig. 2); and a control device 40 for controlling the operations of the constituent elements of the die casting machine 1.

In order to suppress the generation of air holes (entrainment air holes) caused by the entrainment of the gas into the molten metal, the die casting machine 1 can perform vacuum suction from the inside of the cavity 7 and the sleeve 11 of the injection device 10 communicating with the cavity 7, respectively, using the vacuum suction system 30.

A cavity 7 (product portion) is formed between the fixed mold 4 and the movable mold 2 provided on the movable plate 3, wherein the movable plate 3 moves forward and backward along the connecting rod 3A. A suction portion 8 that communicates with the cavity 7 and is connected to a vacuum pipe of the vacuum suction system 30 is provided at a boundary portion between the movable mold 2 and the fixed mold 4. The suction unit 8 is provided, for example, in a cooling exhaust port (cool-Vent). Alternatively, the suction unit 8 may be a vacuum valve.

In a state where the inside of the cavity 7 and the sleeve 11 is depressurized by the vacuum suction system 30, molten metal such as aluminum or aluminum alloy is injected toward the cavity 7 by the injection device 10 and filled into the cavity 7, thereby producing a cast molded article.

(Structure of injection device)

The injection device 10 includes: a sleeve 11 to which molten metal is supplied from the inside; a plunger 20 which can advance and retreat with respect to the sleeve 11 inside the sleeve 11; and a driving source such as a hydraulic cylinder, not shown, for driving the plunger 20.

In the injection device 10, the front side in the moving direction of the plunger 20 at the time of injecting the molten metal, that is, the side F close to the cavity 7 is defined as "front", and the side B far from the cavity 7 is defined as "rear". That is, the plunger 20 advances and retreats in the front-rear direction D1.

(Sleeve)

The sleeve 11 is a linearly extending cylindrical body. The axial direction of the sleeve 11 coincides with the front-rear direction D1. The front side of the sleeve 11 penetrates the fixed disk 5 and communicates with a space 41A of a die sleeve 41 provided in the fixed die 4.

The rear side of the sleeve 11 protrudes outside the fixed disk 5, and extends in the horizontal direction toward the rear. A pouring nozzle 110 for pouring molten metal by a ladle, not shown, is provided near the rear end 11B of the sleeve 11. The gate 110 penetrates an upper portion of the peripheral wall 111 of the sleeve 11.

The reservoir is formed by including a space (front space 112) in front of the punch 21 in the sleeve 11 and a space 41A of the die sleeve 41. The reservoir communicates with the cavity 7 via a runner 42 and a gate 43.

A plurality of

suction ports

101 and 102 penetrating the inside and outside of the sleeve 11 are formed in the peripheral wall 111 of the sleeve 11. The

suction ports

101 and 102 are individually connected to vacuum pipes of the vacuum suction system 30 (fig. 2).

The

suction ports

101 and 102 are arranged in the front-rear direction D1 in the circumferential wall 111 at a position forward of the pouring port 110, and each penetrate the circumferential wall 111 in the thickness direction. Hereinafter, the first suction port 101 (# 1) and the second suction port 102 (# 2) are referred to in this order from the side close to the pouring gate 110. The first suction port 101 and the second suction port 102 are disposed above the peripheral wall 111 so as to avoid the contact with the molten metal M.

By the plurality of

suction ports

101 and 102 arranged in the front-rear direction D1, the front space 112 and the space 203A of the suction concave portion 203 located rearward of the front space 112 can be continuously sucked from the position distributed in the front-rear direction D1 in the injection filling process.

More than 3 suction ports can be formed in the peripheral wall 111 in accordance with the axial length of the sleeve 11, the required vacuum degree of the interior of the sleeve 11, and the like. For example, the third suction port and the fourth suction port may be added to the front side of the second suction port 102. The suction ports can be arranged at equal or variable intervals in the front-rear direction D1.

The first suction port 101 and the second suction port 102 are through holes having circular cross sections of the same diameter. However, the first suction port 101 and the second suction port 102 do not necessarily need to be the same diameter, and the shape of their openings is not limited. One or both of the first suction port 101 and the second suction port 102 may be formed in an oblong shape long in the front-rear direction D1 or in an oblong shape long in the circumferential direction of the sleeve 11.

As described later, a larger opening area is easily secured to the

suction ports

101 and 102 of the sleeve 11 than the opening area of the rear suction path 204 (fig. 3) penetrating a part of the punch 21. If the number of suction ports is increased to increase the total opening area, the suction capacity can also be increased.

(plunger)

The plunger 20 includes a punch 21 for extruding the molten metal in the sleeve 11 forward and a rod 22 for supporting the punch 21 from behind.

The rod 22 is coupled to a piston rod of a hydraulic cylinder, not shown, via a coupling, not shown. The plunger 20 advances from a predetermined origin position toward the cavity 7 by a predetermined injection stroke by the driving force of the hydraulic cylinder, thereby injecting molten metal, and retreats to the origin position when the injection is completed.

As shown in fig. 3, the plunger 20 includes: a punch body 201 including at least a front end 20F of the punch 21; a punch rear 202 located on the rod 22 side; a suction recess 203 located between the punch body 201 and the punch rear 202, and forming a space 203A for preventing inflow of outside air inside the peripheral wall 111 of the sleeve 11; and a rear suction path 204 (# 4) that communicates with the suction recess 203 from a position rearward of the punch rear 202.

A cooling mechanism, not shown, for circulating a cooling medium such as water is typically provided inside the punch 21. By this cooling mechanism, thermal expansion of the punch 21 can be suppressed.

The punch body 201 is a columnar member disposed inside the inner peripheral portion of the peripheral wall 111.

The punch rear portion 202 is a columnar member disposed inside the inner peripheral portion of the peripheral wall 111 at a position rearward of the punch body 201. The punch rear 202 is mounted to the rod 22 via a joint 23.

The same or different clearances are set between the punch body 201 and the inner peripheral portion of the peripheral wall 111 and between the punch rear portion 202 and the inner peripheral portion of the peripheral wall 111, respectively.

The suction recess 203 is retracted radially inward of the punch body 201 with respect to the inner peripheral portion of the peripheral wall 111. The suction recess 203 is divided over the entire circumference by the rear end 201B of the punch body 201 and the front end 202A of the punch rear portion 202, and the outer circumference of the small diameter portion 203D having a smaller diameter than the respective diameters of the punch body 201 and the punch rear portion 202. The molten metal M in the front space 112 does not substantially enter the inside of the suction recess 203 beyond the clearance between the punch body 201 and the sleeve 11. Even if a small amount of molten metal M enters the suction concave portion 203 from the front space 112, a space 203A in which the molten metal M is not present remains in substantially the entire region including the upper portion of the suction concave portion 203.

The suction recess 203 provides such a space 203A: the first and

second suction ports

101 and 102 of the sleeve 11 are depressurized rearward of the punch body 201 by vacuum suction through at least one of the rearward suction paths 204. By providing the depressurized space 203A rearward of the front space 112, the outside air can be prevented from flowing into the front space 112, which is negative in pressure with respect to the outside atmosphere (outside air), through the gap between the punch 21 and the sleeve 11. This is because the pressure P of the space 203A of the suction concave portion 203 sucked by the vacuum suction system 30, respectively ₁ Pressure P with the front space 112 ₂ Without pressure difference therebetween, or even with pressure difference (P ₁ -P ₂ ) And atmospheric pressure P ₀ Pressure P with the front space 112 ₂ Difference (P) ₀ -P ₂ ) As compared with the case where the air is small enough, the inflow of the outside air into the front space 112 through the suction concave portion 203 is suppressed.

If the external air flows into the front space 112 where the molten metal M is stored, the molten metal M bubbles and flies or the liquid surface is severely shaken. By preventing the inflow of the external air into the front space 112, it is possible to prevent the turbulence of the molten metal M, and also to prevent the deterioration of the vacuum degree of the front space 112 due to the inflow of the external air, and to keep the pressure of the front space 112 low with respect to the pressure of the cavity 7, so that the preceding molten metal (preceding molten metal) can be prevented. By preventing the prior molten metal, product defects such as chipping (chipping), peeling (peeling), curling (Striping for shot blast) and the like can be reduced.

In order to more sufficiently suppress inflow of the external air into the suction recess 203 from the space (rear space 113) behind the punch rear 202, it is preferable to provide an annular seal member 205 in the punch rear 202 or to fill a seal between the outer peripheral portion of the punch rear 202 and the inner peripheral portion of the peripheral wall 111, for example. The sealing member 205 or the sealant may be provided on the outer peripheral portion of the punch body 201. In addition, the lubricant supplied to the punch 21 in the casting process also contributes to sealing between the outer peripheral portion of the punch 21 and the inner peripheral portion of the sleeve 11.

The rear suction path 204 extends rearward from the suction recess 203 through the punch rear 202, and is connected to a vacuum pipe of the vacuum suction system 30. The rear suction path 204 includes, for example: a through hole 204A that penetrates the punch rear portion 202 in the axial direction at the upper portion of the punch rear portion 202 and communicates with the space 203A; and a suction pipe 204B connected to the through hole 204A and extending rearward along the rod 22 in a space (rear space 113) rearward of the punch rear 202. The rear space 113 is at atmospheric pressure and corresponds to an external air space. The suction pipe 204B is connected to a vacuum pipe of the vacuum suction system 30 so as to allow relative displacement in the front-rear direction D1 with advance and retreat of the plunger 20. The rear suction path 204 is not opened to the atmosphere regardless of the position of the plunger 20. The

suction ports

101 and 102 are opened to the atmosphere according to the position of the plunger 20.

The rear suction path 204 does not necessarily need to include the through hole 204A of the punch rear portion 202, and may include a groove formed at the upper end of the punch rear portion 202, for example.

In addition, a through hole may be formed in the joint 23 or the rod 22 as a part of the rear suction path 204 instead of the suction pipe 204B.

Further, there may be 2 or more rear suction paths 204 communicating with the space 203A (for example, refer to fig. 7 (a)).

The punch 21 may be assembled from a plurality of members, or may be integrally formed by cutting a single member. For example, the punch 21 can be assembled from a component corresponding to the punch body 201, a component corresponding to the small diameter portion 203D, and a component corresponding to the punch rear portion 202.

(control device)

The control device 40 (fig. 1) controls the components of the die casting machine 1 including the injection device 10, the vacuum suction system 30, and a pouring device not shown in the drawings according to the manufacturing conditions, and repeatedly performs a series of steps including the steps of closing the mold, pouring, filling by injection, pressurizing/holding pressure, cooling, opening the mold, taking out the product, supplying a release agent to the mold, retracting the plunger, supplying a lubricant to the punch 21, and the like, for a predetermined cycle time.

The control device 40 detects the position of the plunger 20 by the position detection unit 20S (fig. 1) and performs drive control of a hydraulic cylinder, not shown, coupled to the plunger 20 in the injection filling and plunger retracting steps. By this control, the plunger 20 is controlled to a predetermined moving speed.

The control device 40 controls the operations of the on-off valve 313 and the vacuum valve 30V of the vacuum suction system 30. In this control, the position of the plunger 20 detected by the position detecting section 20S is used.

As the position detecting unit 20S, for example, a linear encoder provided on a piston rod of a hydraulic cylinder coupled to the rod 22 of the plunger 20 is preferably used.

Further, the position of the plunger 20 can also be detected using a switch lever provided to the lever 22 and a plurality of limit switches operated by the switch lever.

Fig. 4 (a) and (b) show an example of a mode of the advancing speed of the plunger 20 in the injection filling step S10. In fig. 4 (a) and (b), the casting pressure, which is the pressure applied to the molten metal by a hydraulic cylinder (not shown) via the plunger 20, is indicated by a broken line.

The injection filling step S10 includes: a low-speed injection step S11 of advancing the plunger 20 in a low-speed region from the home position; and a high-speed injection step S12 of increasing the advancing speed of the plunger 20 to a high-speed region in the middle of the injection stroke, and extruding the molten metal M from the sleeve 11 by the punch 21 to inject the molten metal M into the cavity 7.

The low-speed injection step S11 is started when the plunger 20 starts to advance, and, for example, when the molten metal M reaches the gate 43 via the runner 42, the process shifts from the low-speed injection step S11 to the high-speed injection step S12. The high-speed injection step S12 is performed, for example, until the cavity 7 is filled with the molten metal M.

The moving speed of the plunger 20 in the low-speed injection step S11 may be fixed as indicated by a two-dot chain line in fig. 4 (a), but the movement of the plunger 20 may be temporarily stopped during the whole stop period t1 as indicated by a solid line in (a), or the plunger 20 may be temporarily decelerated during the whole deceleration period t2 as indicated by (b). Before and after stopping or decelerating the plunger 20, the suction from the front space 112 is performed by using the first suction port 101 and the second suction port 102, or the suction from the suction recess 203 may be performed by at least one of the first suction port 101, the second suction port 102, and the rear suction path 204, even though the suction is not necessarily performed in parallel therewith.

Here, "throughout" before and after stopping or decelerating means: the suction of the suction concave portion 203 is continuously performed from a time before the start of the stop or deceleration to a time after the end of the stop or deceleration.

In order to prevent the inflow of the external air into the front space 112, at least the suction concave portion 203 out of the front space 112 and the suction concave portion 203 may be continuously sucked as much as possible throughout the entire injection filling process S10.

By stopping and decelerating the plunger 20 in the injection filling step S10, even if the axial length of the sleeve 11 is short with respect to the advancing speed of the plunger 20 or the required vacuum degree of the front space 112, the time for vacuum suction can be sufficiently ensured to achieve the required vacuum degree.

After the plunger 20 increases speed to the high speed region, the control device 40 switches from the speed control based on the speed of the plunger 20 to the pressure control based on the pressure of the molten metal in the cavity 7 (pressure maintaining control/pressurizing control) based on the signal of the position detection unit 20S detecting that the plunger 20 reaches the speed-pressure switching position (VP (Velocity Pressure) switching position), for example, and shifts to the pressurizing and holding step S20.

After that, when the molten metal in the cavity 7 is sufficiently solidified while the casting pressure is increased and maintained at the predetermined casting pressure, the movable plate 3 is moved to open the

molds

2 and 4. When the

molds

2, 4 are opened, the product is pushed out from the cavity 7 by driving the product pushing mechanism 2A, and therefore the product can be taken out from the

molds

2, 4.

In order to compress and crush the air involved in the molten metal by transmitting a high pressure to each corner of the cavity 7 by pressurizing the molten metal injected into the cavity 7 when the temperature of the molten metal is high, it is desirable to transfer the molten metal to the pressurizing and holding step S20 immediately after the molten metal is filled into the cavity 7. Therefore, the time required for the response of the valve or the hydraulic oil in the hydraulic circuit including the hydraulic cylinder coupled to the plunger 20 is estimated in advance, and the speed-pressure switching position is set to a position further rearward by a set length than the filling completion position at which the filling of the molten metal into the cavity 7 is completed in the injection stroke of the plunger 20.

(vacuum suction System)

An example of the structure of the vacuum suction system 30 will be described with reference to fig. 2. The vacuum suction system 30 includes: a vacuum pump 31; a vacuum tank 32 provided with a pressure gauge 32A, the vacuum tank being configured to depressurize the interior by operation of the vacuum pump 31; a sleeve suction system 30S that sucks the inside of the sleeve 11 through the first suction port 101, the second suction port 102, and the rear suction path 204; a mold suction system 30M for directly sucking the cavity 7 through a suction portion 8 provided in the

molds

2, 4; and a pressurized air supply system 30P that performs a blasting process.

According to the example shown in fig. 2, the sleeve suction system 30S and the mold suction system 30M serve as the vacuum tank 32, but the present invention is not limited thereto, and the sleeve suction system 30S and the mold suction system 30M may be configured separately.

In the mold suction system 30M, from the upstream of the air flow sucked by the cavity 7, there are disposed in order: a vacuum filter 301 for vacuum suction; a pressure detection unit 302 that is a pressure gauge, a coupling unit, a pressure sensor, or the like that detects the pressure in the piping of the mold suction system 30M; and a vacuum valve 303 for communicating the suction unit 8 with the vacuum tank 32.

The vacuum filter 301 suppresses the following: fine droplets of molten metal, which may be mixed into the sucked gas, molten metal slag as a solidified sheet, a mold release agent, dust, and the like enter the mold suction system 30M. The vacuum filter 311 provided in the sleeve suction system 30S also similarly suppresses molten metal slag, lubricant, dust, and the like from entering the sleeve suction system 30S.

When the vacuum valve 303 is opened, the gas of the cavity 7 is sucked from the suction portion 8 to the mold suction system 30M based on the pressure difference between the inside of the vacuum tank 32 and the cavity 7. In the vacuum suction, it is preferable to monitor the pressure detected by the pressure detecting unit 302 to confirm that the vacuum suction is normally performed.

The sleeve pumping system 30S includes: a vacuum valve 30V; suction paths 310 (# 1, #2, # 4) corresponding to the first suction port 101, the second suction port 102, and the rear suction path 204 of the sleeve 11, respectively; and a confluence distribution portion 314 connected to the suction paths 310.

In each suction path 310, from the upstream of the air flow sucked from the inside of the sleeve 11, there are provided in order: a vacuum filter 311 for vacuum suction; a pressure detection unit 312 that is a pressure sensor or the like that detects the pressure in the suction path 310; and an opening/closing valve 313 that opens or closes the suction path 310.

The vacuum valve 30V can be switched to the following state: a vacuum suction state in which each suction path 310 communicates with the vacuum tank 32; a blowing state in which each suction path 310 communicates with the pressurizing tank 322; and a neutral state in which each suction path 310 is not communicated with both the vacuum tank 32 and the pressurizing tank 322. When the vacuum valve 30V is in the vacuum suction state, vacuum suction can be performed through the suction path 310 in a state where the opening/closing valve 313 is opened.

By sending a control command for opening or closing the on-off valve 313 from the control device 40, it is possible to communicate all or a part of the first suction port 101, the second suction port 102, and the rear suction path 204 with the vacuum tank 32 to perform vacuum suction according to the position of the plunger 20, the filling rate of the molten metal M in the front space 112, the pressure detected by the pressure detecting unit 312, and the like.

From the viewpoint of reducing the pressure in the sleeve 11 to a sufficiently high vacuum in a short time, it is preferable to perform vacuum suction by using

more suction ports

101, 102 to ensure a larger total opening area.

When the on-off valve 313 of the suction path 310 (# 1) connected to the first suction port 101 is opened, the first suction port 101 and the vacuum tank 32 communicate via the suction path 310. Then, based on the pressure difference between the inside of the vacuum tank 32 and the inside of the sleeve 11, the gas inside the sleeve 11 flows into the suction path 310 through the first suction port 101. The gas flowing into the suction path 310 through the first suction port 101 is merged with the fluid from the other suction path 310 in the merging and distributing section 314 via the vacuum filter 311, the pressure detecting section 312, and the on-off valve 313, and then flows into the vacuum tank 32 via the vacuum valve 30V.

The suction path 310 (# 2) connected to the second suction port 102 and the suction path 310 (# 4) connected to the rear suction path 204 are also similar, and vacuum suction can be performed by opening the corresponding opening/closing valve 313.

In the present embodiment, the first suction port 101, the second suction port 102, the rear suction path 204, and the suction paths 310 are also used as paths for blowing air after the injection is completed. By blowing air, molten metal slag can be removed from the suction path 310, the

suction ports

101 and 102, and the rear suction path 204.

The pressurized air supply system 30P for performing the air blowing process includes: a compressed air source 321 as a supply source of pressurized air; and a pressurized tank 322 to which air is fed by the compressed air source 321 to accumulate pressure therein.

Since the suction path 310 upstream of the merging and distributing section 314 (upstream of the time of vacuum suction) is common to the time of vacuum suction and the time of air blowing, vacuum suction and air blowing can be continuously performed by switching the connection destination of the merging and distributing section 314 to the vacuum tank 32 and the pressure tank 322 by the vacuum valve 30V.

The pressurized air supply system 30P is also used for blowing of the mold suction system 30M after the mold opening. Therefore, the connection destination of the suction path of the mold suction system 30M can be switched to the vacuum tank 32 and the pressurization tank 322 by the vacuum valve 303. The flow rate of the air blast can be adjusted by a flow rate adjustment Valve such as a global Valve (not shown) provided between the vacuum Valve 303 and the pressurization tank 322. In addition, the mold suction system 30M may also be connected to a pressurized tank and a compressed air source other than the pressurized tank 322 and the compressed air source 321.

When the vacuum valve 30V is switched to blow, pressurized air is distributed from the pressurized tank 322 to the suction paths 310 through the merging and distributing portion 314, and is ejected from the first suction port 101, the second suction port 102, and the rear suction path 204, respectively. By sequentially switching the opening and closing of the opening/closing valves 313 corresponding to the first suction port 101, the second suction port 102, and the rear suction path 204, and performing the air blowing one by one, the positive pressure of the pressurized air can be managed, and the state of clogging of each suction path 310 can be detected based on the measurement value of the pressure detection unit 312. In addition, the flow rate of the air blast can be increased to improve the cleaning effect. The flow rate of the air blast can be adjusted by a flow rate adjustment Valve such as a ball Valve (not shown) provided between the vacuum Valve 30V and the pressure tank 322.

(use example of suction port of sleeve and rear suction path)

The relative positional relationship between the first suction port 101 and the second suction port 102 and the plunger 20 varies depending on the position of the plunger 20 relative to the sleeve 11. For example, as shown in fig. 3, when the second suction port 102 is opened in the front space 112 in front of the punch body 201, gas can be sucked from the front space 112 through the second suction port 102.

Since the sprue 110 is open to the atmosphere, suction from the front space 112 is premised on: the gate 110 is closed by the punch body 201. Thus, a front space 112 as a closed space is formed in front of the punch body 201. By applying suction from the front space 112, the pressure of the cavity 7 communicating with the front space 112 can be reduced.

Further, for example, when the first suction port 101 is located immediately above the suction recess 203 of the punch 21, suction of the space 203A from the suction recess 203 can be performed (see fig. 5 (a)). The suction from the suction recess 203 is performed on the premise that the pouring gate 110 is closed by the punch rear 202, and thus the suction recess 203 is formed as a closed space in front of the punch rear 202.

In addition, the inventors confirmed from the test results that: as will be described later, when the suction port (the second suction port 102 in the example shown in fig. 3) farthest forward from the pouring port 110 is closed by the punch rear portion 202 and the suction from the suction recess 203 is completed, the molten metal moves from the front space 112 to the previous molten metal in the cavity 7 due to the pressure difference. The reason why the previous molten metal is generated is that the vacuum degree is deteriorated by the inflow of the external air into the front space 112. In addition, it was confirmed from the test results that: even if the suction port is closed by the punch body 201 before the suction port farthest forward from the pouring port 110 is closed by the punch rear portion 202, the suction from the front space 112 is ended, and the suction from the suction concave portion 203 is continued, so that the preceding molten metal can be suppressed.

In the example shown in fig. 3, the second suction port 102 is the furthest forward suction port from the pouring port 110, and after the second suction port 102 is closed by the punch body 201, the suction from the front space 112 is completed. After the second suction port 102 is closed by the punch rear portion 202, the suction from the suction recess 203 through the suction port of the sleeve 11 is completed. On the other hand, suction from the suction recess 203 through the rear suction path 204 can be performed even after the suction through the second suction port 102 is completed, regardless of the position of the plunger 20.

According to the above, if suction of the suction recess 203 is continued by using the rear suction path 204 at least after the suction port farthest from the pouring port 110 is closed by the punch rear portion 202, inflow of external air can be prevented, and it is effective for suppressing disturbance of molten metal and generation of the preceding molten metal.

The capability of vacuum suction through the first suction port 101 and the second suction port 102 of the sleeve 11 varies with the projected areas projected to the front space 112 and the suction concave portion 203, respectively, which are objects of suction.

For example, the second suction port 102 shown in fig. 3 is substantially fully opened with respect to the front space 112, and when the second suction port 102 is projected in the hole axis direction, the second suction port 102 is projected to the front space 112 over the entire area of the opening 102A, and therefore the projected area projected to the front space 112 is maximized. At this time, the suction capacity of suction from the front space 112 through the second suction port 102 is maximized.

When the plunger 20 advances to the position shown by the one-dot chain line in fig. 3, half of the opening 102A of the second suction port 102 is closed by the punch body 201, and therefore the second suction port 102 is projected to the front space 112 in a state of lacking half of the opening area. As the projected area decreases, the suction capacity decreases.

When the plunger 20 advances to the position shown by the two-dot chain line in fig. 3, the entire area of the opening 102A of the second suction port 102 is closed by the punch body 201, and therefore the projected area of the second suction port 102 projected toward the front space 112 is smallest, at which time the suction capacity by the second suction port 102 from the front space 112 is smallest.

The same applies to the suction recess 203. For example, in fig. 3, when the first suction port 101 is projected in the hole axis direction with respect to the space 203A, the projected area of the first suction port 101 is largest, and the suction capacity sucked from the suction concave portion 203 through the first suction port 101 is largest. As the projected area of the first suction port 101 decreases due to the advance or the retreat of the plunger 20, the suction capacity sucked from the suction recess 203 through the first suction port 101 also decreases.

The rear suction path 204 is always in communication with the suction recess 203 irrespective of the position of the plunger 20 in the front-rear direction D1, and the projected area of the rear suction path 204 projected in the axial direction of the hole with respect to the space 203A of the suction recess 203 is fixed irrespective of the position of the plunger 20. Therefore, a fixed suction capacity can be obtained by the rear suction path 204 independently of the position of the plunger 20.

As shown in fig. 5 (a) and (b), even if the diameters or pitches of the first suction port 101 and the second suction port 102 and the lengths of the respective portions 201 to 203 of the punch 21 in the front-rear direction D1 are different from those of the example shown in fig. 3, the same is true in the following point: the projected area of each

suction port

101, 102 depends on the position of the plunger 20The device changes, and the suction capacity changes accordingly. Fig. 5 (a) shows the projection area a with respect to the projection of the suction recess 203 through the first suction port 101 ₁ And the state of maximum suction capacity, fig. 5 (b) shows the projected area a ₁ And a state where the suction capacity is minimum.

By advancing the plunger 20 to the position shown in fig. 5 (c), when the first suction port 101 is opened to the rear space 113 of the punch rear portion 202, that is, the atmosphere, the opening/closing valve 313 corresponding to the first suction port 101 is closed in order to prevent the external air from flowing from the first suction port 101 into the suction path 310.

The graph of fig. 6 shows a change in the projected area of the suction port of the sleeve 11 projected to the suction recess 203 with respect to the injection stroke (position in the front-rear direction D1) of the plunger 20. In the example shown in fig. 6, 3 suction ports of the same diameter are arranged at equal intervals in the front-rear direction D1. The vertical axis of the graph represents the area ratio when the maximum projection area of the suction port onto the suction concave portion 203 is set to 100%. As the plunger 20 advances, as is clear from fig. 5 (a) to (c), the suction ports 101 to 103 are sequentially opposed to the suction recess 203, and the respective suction ports of the sleeve 11 are sequentially closed by the punch rear portion 202, so that the area ratio periodically varies from 100% as the upper limit to 20% as the lower limit in this example, depending on the position of the plunger 20. The lower limit of the area ratio varies depending on the diameter of the suction port, the pitch, the length of each portion 201 to 203 of the punch, and the like, 20% being an example.

After the suction from the suction recess 203 is completed (END of fig. 6) through the suction port, at least from the viewpoint of securing the minimum suction capability before the completion, in the example shown in fig. 6, an opening area corresponding to 20% or more of the lower limit area ratio may be set for the rear suction path 204. The opening area of the rear suction path 204 corresponds to the projection area projected from the rear suction concave portion 203. That is, if the projection area of the rear suction path 204 projected to the suction concave portion 203 is a ₂ Then A ₂ Preferably, the projection area A of the suction port is set to be periodically changed with respect to the position of the plunger 20 ₁ Is above the lower limit of (2).

The opening area required for the rear suction path 204 can be set in consideration of the pressure loss in the rear suction path 204, etc., in addition to the projection area of the suction port of the sleeve 11 onto the suction concave portion 203.

Regarding the suction of the suction recess 203 by the rear suction path 204, even before the suction by the second suction port 102 of the sleeve 11 is completed, the suction by the rear suction path 204 from the suction recess 203 can be continuously performed in parallel with the suction by the suction port of the sleeve 11, because the suction can be performed regardless of the position of the plunger 20. This can strengthen the suppression of the inflow of the external air before the end of the suction through the second suction port 102.

(vacuum suction of the sleeve)

An example of the procedure of vacuum suction of the sleeve 11 in the injection filling step will be described below with reference to fig. 7 to 9.

The control device 40 controls the plunger 20 to a predetermined speed by driving a hydraulic cylinder, not shown, and opens and closes each opening/closing valve 313 of the vacuum suction system 30 based on the position of the plunger 20 detected by the position detecting unit 20S.

The plunger 20 shown in fig. 7 (a) is stopped at the home position X ₀ . Original position X ₀ For example, at the rear end 110B of the spout 110.

The plunger 20 is moved from the home position X ₀ Advancing, the gate 110 is closed by the punch rear 202 when the front end 202A of the punch rear 202 reaches the position of the front end 110A of the gate 110. After the pouring spout 110 is closed, for example, as shown in fig. 7 (b), the suction recess 203 and the front space 112 are each divided into closed spaces, so that vacuum suction can be started from the suction recess 203 and the front space 112, respectively. Immediately after the spout 110 is closed, suction can begin through the rear suction path 204. In addition, if a part of the suction concave portion 203 also communicates with the first suction port 101, suction can be started through the first suction port 101.

In the control example shown in fig. 7 to 9, 2 rear suction paths 204 are provided in the punch rear portion 202. These rear suction paths 204 are connected to the same suction path 310 (# 4) of the vacuum suction system 30 (fig. 2).

Here, in order to prevent inflow of the external air, suction (s 02) through the second suction port 102 is started after suction (s 01) through the suction concave portion 203 is started (concave portion suction step s01 and front space suction step s 02). Suction of the suction recess 203 can be performed by at least one of the first suction port 101 and the rear suction path 204. As described above, the control command to open the on-off valve 313 corresponding to at least one of the first suction port 101 and the rear suction path 204 is issued from the control device 40, and the control command to open the on-off valve 313 corresponding to the second suction port 102 is issued simultaneously with or after the control command is issued. In this way, when the decompression of the front space 112 starts, the decompression of the suction concave portion 203 starts, so that the following can be prevented: immediately after the front space 112 starts to be depressurized, the outside air flows into the front space 112 based on the pressure difference from the atmospheric pressure.

In the example shown in fig. 7 (B), the position of the plunger 20 at which the front end 202A of the punch rear portion 202 reaches the rear end 101B of the first suction port 101 beyond the front end 110A of the gate 110 is determined as the vacuum start position X ₁ 。

The relative positions of the sleeve 11 and the plunger 20 are indicated by circles with broken lines surrounding the focused region. The suction from the suction concave portion 203 through the first suction port 101 or the second suction port 102 is indicated by a solid line arrow, the suction from the suction concave portion 203 through the rear suction path 204 is indicated by a broken line arrow, and the suction from the front space 112 through the second suction port 102 is indicated by a two-dot chain arrow. The arrow indicated by a single-dot chain line indicates that the outside air is to flow forward from the rear space 113 through the gap between the punch 21 and the sleeve 11. The same applies to fig. 8 and 9.

In the vacuum suction performed from the suction concave portion 203 and the front space 112, the external air flowing forward through the gap between the punch 21 and the sleeve 11 is sucked into the suction path 310 through the

suction ports

101, 102 or the rear suction path 204.

In the example shown in fig. 7 (b), the first suction port 101 is located directly above the suction recess 203, and the opening of the first suction port 101 is projected to the suction recess 203 over the entire area of the opening, without being blocked by the punch body 201 or the punch rear portion 202, according to the interrelationship of the diameters, the pitches, the lengths of the portions 201 to 203 of the first suction port 101 and the second suction port 102, and the like. Further, since the second suction port 102 is located forward of the punch body 201, the second suction port 102 is opened to the front space 112 over the entire area of the opening. Accordingly, suction can be performed from the suction concave portion 203 and the front space 112 with maximum suction efficiency through the first suction port 101 and the second suction port 102. Further, by also performing suction from the suction recess 203 via the rear suction path 204, the suction efficiency is further improved.

By suction through the first suction port 101, the second suction port 102, and the rear suction path 204, the front space 112 can be efficiently and sufficiently depressurized while preventing inflow of outside air. At this time, the vacuum degree of the front space 112 can be more sufficiently increased by temporarily stopping or decelerating the advance of the plunger 20. By keeping the vacuum degree of the front space 112 higher than that of the cavity 7 and making the outside air not flow into the front space 112 by suction by the suction concave portion 203, the previous molten metal is prevented. The vacuum suction directly from the cavity 7 can be performed by the die suction system 30M after the pouring port 110 is blocked by the punch body 21, but may be performed at an appropriate timing after the start of suction in the front space 112 in order to prevent the preceding molten metal.

Next, as shown in fig. 7 (c), when the plunger 20 is advanced to the position where the front end 202A of the punch rear portion 202 reaches the front end 101A of the first suction port 101, the punch body 201 is located directly below the second suction port 102, and the punch rear portion 202 is located directly below the first suction port 101. This corresponds to a state in which the first suction port 101 and the second suction port 102 are closed, and thus the suction efficiency is lowered. Before the first suction port 101 is opened to the atmosphere by further advancing the plunger 20, a command to close the opening/closing valve 313 corresponding to the first suction port 101 is issued by the control device 40. Since the closing operation of the opening/closing valve 313 is delayed with respect to the occurrence of the closing command, the suction by the first suction port 101 through the gap between the punch rear portion 202 and the sleeve 11 can be continuously performed in addition to the suction by the second suction port 102 through the gap between the punch main body 201 and the sleeve 11 until the opening/closing valve 313 corresponding to the first suction port 101 is actually closed after the occurrence of the closing command.

The thin solid line shown in fig. 7 (c) shows a state near the end of suction by a closing command sent to the opening/closing valve 313 corresponding to the first suction port 101.

As shown in fig. 8 (a), when the plunger 20 is advanced to the position where the rear end 202B of the punch rear portion 202 reaches the rear end 101B of the first suction port 101, the first suction port 101 communicates with the rear space 113 and is opened to the atmosphere. The opening/closing valve 313 corresponding to the first suction port 101 has been closed, and suction through the first suction port 101 is stopped. Therefore, the external air does not flow from the first suction port 101 into the suction path 310. At this time, since the suction concave portion 203 communicates with the second suction port 102, the reduced pressure space 203A can be continuously provided at a position rearward of the front space 112 by suction performed through the suction concave portion 203, and at the same time, the inflow of the outside air into the front space 112 from the rear can be prevented.

Next, as shown in fig. 8 (b), when the plunger 20 advances to a position where the front end 202A of the punch rear portion 202 reaches the front end of the second suction port 102, since the punch rear portion 202 exists over the entire projection range of the second suction port 102, the suction efficiency is lowered due to the closing of the second suction port 102. Before the second suction port 102 is opened to the atmosphere by further advancing the plunger 20, a command to close the opening/closing valve 313 corresponding to the second suction port 102 is issued by the control device 40. After the closing instruction is issued, the suction can be continued by the second suction port 102 through the gap until the opening/closing valve 313 corresponding to the second suction port 102 is actually closed. The suction performed through the second suction port 102 is indicated by an arrow of a thin solid line since the end is scheduled.

The displacement amount of the plunger 20 from fig. 7 (c) to fig. 8 (b) corresponds to the total length of the dimension L1 between the first suction port 101 and the second suction port 102 and the diameter L2 of one suction port. When other suction ports are arranged in the front-rear direction D1 in front of the second suction port 102, the steps corresponding to fig. 7 (c) and 8 (a) are repeated a number of times corresponding to the number of suction ports.

When the second suction port 102 is closed as shown in fig. 8 (b), and the plunger 20 is advanced to a position where the second suction port 102 is opened to the atmosphere as shown in fig. 8 (c), the opening/closing valve 313 corresponding to the second suction port 102 is closed, and suction through the second suction port 102 is stopped, so that the outside air does not flow from the second suction port 102 to the suction path 310. At this time, since no other suction port exists in the front of the second suction port 102, the suction means for sucking from the suction concave portion 203 is ensured only by the rear suction path 204. In order to prevent the outside air from flowing into the front space 112 by suction from the suction concave portion 203, suction through the rear suction path 204 is started at least before suction of the second suction port 102 farthest forward from the pouring port 110 is stopped (rear suction step s 03). The suction through the rear suction path 204 may be started when the second suction port 102 shown in fig. 8 (b) is closed.

In this example, the suction for the suction concave portion 203 by the rear suction path 204 starts from the vacuum start position shown in fig. 7 (b), and the suction of the suction concave portion 203 is continued by the suction via the rear suction path 204, throughout the front and rear sides where the suction of the second suction port 102 is stopped. Therefore, a pressure difference (P) is applied between the front space 112 and the space 203A of the suction concave portion 203, which is greater than the pressure difference between the front space 112 and the outside air, before and after the suction of the second suction port 102 is stopped ₀ -P ₂ ) Small pressure difference (P ₁ -P ₂ )。

The control device 40 is configured to move the plunger 20 from the home position X ₀ After moving at a low speed, the advancing speed is switched to a high speed, and the molten metal M is extruded from the sleeve 11 by the punch 21 and injected into the cavity 7 via the die sleeve 41 ((a) of fig. 9). Control ofThe device 40 is based on detecting whether the punch body 201 reaches the speed-pressure switching position X _VP The control is switched from the speed control based on the speed of the plunger 20 to the pressure control based on the pressure of the molten metal in the cavity 7 by the signal of the position detecting section 20S. Along with this, the process shifts from the injection filling step S10 to the pressurizing and holding step S20.

As for suction from the suction recess 203 through the rear suction path 204, the opening/closing valve 313 corresponding to the rear suction path 204 is maintained open, and thereby the punch body 201 reaches the speed/pressure switching position X at least as shown in fig. 9 (b) _VP The suction is continued until that (recess suction continuation step s 04).

By the suction from the suction concave portion 203, the inflow of the external air into the void where the molten metal exists can be prevented even in the final stage of the injection filling step S10, whereby turbulence of the molten metal and entrainment of the air into the molten metal can be suppressed. Since the inflow of the external air is prevented by the suction from the suction concave portion 203 from the start of the vacuum in the sleeve 11 shown in fig. 7 (b) to the end of the injection filling step S10, the occurrence of the entrainment of the air holes and the preceding molten metal can be suppressed, and the clogging of the suction path 310 and the like due to the inflow of the molten metal slag together with the external air can be suppressed, so that the vacuum suction can be performed stably and efficiently. Therefore, it is possible to contribute to stabilizing the quality of the cast product and improving the productivity.

As shown in fig. 9 (b), the punch 21 exceeds the speed-pressure switching position X _VP The cavity 7 is filled with molten metal while being extruded. As shown in fig. 4 (a) or (b), in the high-speed injection step S12, while the plunger 20 is advancing, a casting pressure balanced with the flow resistance in the gate 43 is generated, but as the filling of the molten metal throughout the entire cavity 7 is completed, the plunger 20 is stopped, and the casting pressure is rapidly increased, and the process shifts to the pressurizing and holding step S20. In the pressurizing and holding step S20, after the casting pressure is further increased, the molten metal is solidified while being maintained at a predetermined value. The punch 21 eventually stops at a position where it advances by the amount of shrinkage associated with solidification of the molten metal.

When detecting whether the punch body 201 reaches the speed-pressure switching position X _VP When a signal is generated from the position detecting unit 20S of (a), the control device 40 issues a control command to close the on-off valve 313 corresponding to the rear suction path 204. When the on-off valve 313 is closed, suction through the rear suction path 204 is stopped.

After the completion of the filling of the molten metal, even if the suction from the suction concave portion 203 is continued through the rear suction path 204 in the pressurizing and holding step S20, the time for sucking the external air flowing from the rear space 113 to the suction concave portion 203 by the sleeve suction system 30S becomes long, and the degree of vacuum in the vacuum tank 32 is allowed to be slightly deteriorated. After the completion of the filling, if the suction from the suction recess 203 through the rear suction path 204 is stopped by closing the opening/closing valve 313 corresponding to the rear suction path 204, the vacuum degree of the vacuum tank 32 is restored to the time of the start of the next cycle by the vacuum pump 31.

At the time of the punch 21 reaching the speed/pressure switching position X _VP In the case (fig. 9 (b)), the die sleeve 41 located in front of the punch 21 is already filled with molten metal (the filling rate of molten metal in the sleeve 11 is 100%), and no void is present. In this state, if the external air flows from the rear to the front of the punch 21, there is a risk of the molten metal being blown off by the external air toward the cavity 7 before the molten metal, and therefore, even after the molten metal fills the die sleeve 41, it is also meaningful to prevent the inflow of the external air until the filling is about to be completed.

In the above control example, it will be indicated that the plunger 20 reaches the speed-pressure switching position X _VP For stopping suction from suction recess 203, wherein the speed-pressure switch position X _VP The position of the plunger 20 near the time of completion of filling (filling completion position X _FC ). Thus, before filling is completed, at least until the plunger 20 reaches the speed-pressure switching position X _VP Since the suction is continuously performed by the suction concave portion 203, the movement of the molten metal to the cavity 7 caused by the inflow of the external air can be suppressed, and the previous melting can be suppressedThe molten metal causes a decrease in casting quality.

If the speed and pressure switch position X is exceeded _VP The suction from the suction concave portion 203 is continued until the completion of the filling or immediately before the completion of the filling, and the preceding molten metal can be prevented more reliably throughout the period until the completion of the filling with no risk of the preceding molten metal. Further, when the temperature of the molten metal is high after the completion of the filling, the pressure is changed to be increased immediately, and the air is compressed and crushed by the pressure transmission to the entire region of the cavity 7, so that the air holes are reduced, which is more preferable.

Therefore, the present invention is not limited to the above-described control example, and the plunger 20 reaches the speed/pressure switching position X _VP After that, for example, if the control device 40 detects that filling has been completed based on the casting pressure, the suction from the suction recess 203 through the rear suction path 204 may be stopped.

The casting pressure (fig. 4 (a) and (b)) is calculated from the pressure on the rod side and the pressure on the head side of the hydraulic cylinder coupled to the rod 22 of the plunger 20, and is monitored by the control device 40. Thus, the control device 40 can detect whether filling is complete by applying a threshold value to the magnitude or rate of increase of the casting pressure, for example. Alternatively, the filling completion position X can be reached by the "plunger 20 detected by the position detecting unit 20S _FC (fig. 9 (b)) "to detect that filling is completed.

When it is detected that the filling is completed based on the casting pressure or the position of the plunger 20, the control device 40 sends a closing instruction to the opening/closing valve 313 corresponding to the rear suction path 204. Here, it is also preferable to adjust the threshold value applied to the casting pressure to the lowering side or to replace the filling completion position X in consideration of the time required for the response of the opening/closing valve 313 _FC According to the plunger 20 reaching the filling completion position X _FC Filling near position X near the position of the set length (backward) before completion _FC ' to detect that filling is complete.

The control device 40 switches the vacuum valve 30V (fig. 2) to supply air in a state where all the opening/closing valves 313 are closed. By sequentially opening the opening/closing valves 313 corresponding to the first suction port 101 and the second suction port 102, the molten metal slag can be removed from the suction path 310 and the

suction ports

101 and 102 by discharging the pressurized air from the first suction port 101 and the second suction port 102, respectively. The molten metal slag that has fallen into the sleeve 11 is discharged toward the rear end of the sleeve 11 by the punch 21 as the plunger 20 retreats.

Cleaning of the rear suction path 204 and the suction recess 203 by blowing can be performed by, for example, returning the plunger 20 to the home position X as shown in fig. 9 (c) ₀ Is performed in a state of (2). At this time, the suction concave portion 203 is exposed rearward from the sleeve 11. Accordingly, the molten metal slag removed from the suction recess 203 by the pressurized air ejected forward from the rear suction path 204 falls outside the sleeve 11, and thus the molten metal slag can be prevented from entering the inside of the sleeve 11.

In the control of the sleeve vacuum suction described above, the on-off valve 313 is opened and closed according to the position of the plunger 20, but instead of the position of the plunger 20, the on-off valve 313 may be opened and closed according to a reference time, for example, an elapsed time from when the plunger 20 starts to move from the home position (at the time of injection start).

(modification of the invention)

Unlike the above-described embodiment, only 1 suction port 101 is formed in the sleeve 11 of the injection device 10-2 according to the modification of the present invention shown in fig. 10. Except for this, the injection device 10-2 and the die casting machine 1-2 provided with the injection device 10-2 are configured in the same manner as the above-described embodiment.

The punch 21 of the plunger 20 includes a suction recess 203 and a rear suction path 204. While the opening/closing valve 313 corresponding to the rear suction path 204 is opened, suction from the suction recess 203 can be continued through the rear suction path 204.

Therefore, as in the control example described with reference to fig. 7 to 9 in the above-described embodiment, under the control of the control device 40, suction from the front space 112 through the suction port 101 is started after suction from the suction concave portion 203 through the rear suction path 204 is started ((a) of fig. 11). In this way, suction through the rear suction path 204 starts before suction through the suction port 101 is closed by the punch rear 202 and stopped as shown in fig. 11 (b). Suction from the suction recess 203 through the rear suction path 204 continues at least until the speed-pressure switching position is reached.

As described above, since the injection filling step S10 can be continued until the final stage to prevent the inflow of the external air to the position ahead of the punch body 201, turbulence of the molten metal, entrainment of the air due to the turbulence, and clogging of the suction path 310 can be suppressed, and the vacuum degree in the sleeve 11 and the die sleeve 41 can be maintained to suppress the generation of the preceding molten metal.

In addition to the above-described configuration, the configuration described in the above-described embodiment may be selected or modified as appropriate without departing from the gist of the present invention.

The plunger 20 may have 2 or more suction recesses 203 spaced apart in the front-rear direction D1. In this case, the suction recess 203 and the punch rear 202 are arranged in a multistage manner at a position rearward of the punch body 201. For example, the first punch rear portion 202-1, the first suction recess 203-1, the second punch rear portion 202-2, and the second suction recess 203-2 are arranged in this order from the rear end toward the front end of the punch 21. Further, suction from the first suction recess 203-1 is performed through a first rear suction path 204-1 communicating with the first suction recess 203-1 from a position rearward of the first punch rear 202-1, and suction from the second suction recess 203-2 is performed through a second rear suction path 204-2 communicating with the second suction recess 203-2 from a position rearward of the second punch rear 202-2. Suction need not be performed from all of the plurality of suction recesses 203, as long as suction is performed from at least a part of the suction recesses 203. The rear suction paths 204 provided to the plurality of suction recesses 203 may be independent of each other or may be shared by a part of the paths. In short, by providing the plurality of suction concave portions 203, even if a part of the suction concave portions 203 is clogged by adhesion of molten metal slag, suction from other suction concave portions 203 can be performed, and thus, inflow of outside air into the front space 112 can be prevented.

Description of the reference numerals

1. 1-2: a die casting machine;

2: a movable die;

2A: a product pushing mechanism;

3: a movable plate;

3A: a connecting rod;

4: fixing a die;

5: a fixed plate;

6: a base;

7: a cavity;

8: a suction unit;

10. 10-2: an injection device;

11: a sleeve;

11B: a rear end;

20: a plunger;

20F: a front end;

20S: a position detection unit;

21: a punch;

22: a rod;

23: a joint;

30: a vacuum pumping system;

30M: a mold suction system;

30P: a pressurized air supply system;

30S: a sleeve pumping system;

30V: a vacuum valve;

31: a vacuum pump;

32: a vacuum tank;

32A: a pressure gauge;

40: a control device (control unit);

41: a mold sleeve;

41A: a void;

42: pouring gate;

43: a gate;

101: a first suction port;

101A: a front end;

101B: a rear end;

102: a second suction port;

102A: an opening;

110: a sprue gate;

110A: a front end;

110B: a rear end;

111: a peripheral wall;

112: a front space;

113: a rear space;

201: a punch body;

201B: a rear end;

202: the rear part of the punch;

202A: a front end;

202B: a rear end;

203: a suction recess;

203A: a space;

203D: a small diameter portion;

204: a rear suction path;

204A: a through hole;

204B: a suction tube;

205: a sealing member;

301: a vacuum filter;

302: a pressure detection unit;

303: a vacuum valve;

310: : a suction path;

311: a vacuum filter;

312: a pressure detection unit;

313: an opening/closing valve;

314: a confluence distribution unit;

321: a compressed air source;

322: a pressurized tank;

A ₁ 、A ₂ : a projected area;

d1: a front-rear direction;

l1: size;

l2: diameter;

m: a molten metal;

P ₀ : atmospheric pressure;

P ₁ 、P ₂ : pressure;

s10: an injection filling procedure;

s11: a low-speed injection step;

s12: a high-speed injection step;

s20: pressurizing and maintaining pressure;

X ₀ : a home position;

X ₁ : a vacuum start position;

X _VP : a speed pressure switching position;

X _FC : a filling completion position;

X _FC ': a position near before filling is completed;

s01: a recess suction step (first step);

s02: a front space suction step (second step);

s03: a rear suction step (third step);

s04: a recess suction continuation step (fourth step);

t1: a stop period;

t2: during deceleration.

Claims

1. An injection device for a die casting machine, the injection device comprising: a sleeve, the inner side of which is supplied with molten metal; and a plunger that is movable in a forward and backward direction inside the sleeve, the injection device injecting the molten metal into a cavity of a die casting machine through the plunger, wherein,

The plunger is provided with: a punch that extrudes the molten metal in the sleeve forward; and a rod for supporting the punch from the rear,

the sleeve is provided with more than 2 suction ports which penetrate the sleeve through the inner side and the outer side and are arranged along the front-back direction,

the plunger includes:

a punch body including at least a front end of the punch;

a suction recess which is retracted radially inward with respect to an inner peripheral portion of the sleeve at a position rearward of the punch body;

a punch rear portion protruding outward in the radial direction with respect to the suction recess portion, the suction recess portion being defined from a rear side; and

and a rear suction path communicating with the suction recess from a position rearward of the rear portion of the punch.

2. An injection device for a die casting machine, the injection device comprising: a sleeve, the inner side of which is supplied with molten metal; and a plunger that is movable in a forward and backward direction inside the sleeve, the injection device injecting the molten metal into a cavity of a die casting machine through the plunger, wherein,

The sleeve is provided with 1 suction port or more than 2 suction ports arranged along the front-back direction, the suction ports penetrate the sleeve in an inner side and an outer side,

the plunger includes:

a punch body including at least a front end of the punch;

a rear suction path communicating with the suction recess from a position rearward of the rear part of the punch,

the injection device comprises a control part configured to control the operation of a suction system capable of sucking through 1 or more of the suction ports and the rear suction path,

the control unit controls the injection device to perform injection according to the position of the plunger or the elapsed time from the start of injection by the plunger,

after the pouring port of the sleeve is closed by the rear part of the punch, suction from the suction recess is started through at least one of the suction port and the rear suction path, after suction from the suction recess is started, suction from a space in front of the punch body is started through the suction port,

Before the suction port farthest forward from the pouring port among the 1 or more suction ports is closed by the rear portion of the punch and suction is stopped, suction from the suction concave portion is started through the rear suction path, or suction is continued until suction from the suction port is stopped, and at least until the plunger reaches a switching position for switching from speed control to pressure control.

3. The injection device of a die casting machine according to claim 2, wherein,

the control unit continues to suck the molten metal from the suction recess through the rear suction path until the molten metal is completely filled into the cavity.

4. An injection device of a die casting machine as claimed in any one of claims 1 to 3, wherein,

the sleeve is provided with more than 2 suction ports arranged along the front-back direction,

if the projection area of the suction opening projected to the suction concave part is A ₁ The rear suction path projects toward the suction recess by a projection area A ₂ ，

Then A ₂ Is set to be equal to or greater than the lower limit of A1 which periodically changes relative to the position of the plunger.

5. A casting method comprising an injection filling step of injecting and filling a molten metal into a cavity of a die casting machine by a plunger that can advance and retreat in the front-rear direction inside a sleeve to which the molten metal is supplied inside,

The plunger is provided with: a punch that extrudes the molten metal in the sleeve toward the front; and a rod for supporting the punch from the rear,

the plunger includes: a punch body including at least a front end of the punch; a suction recess which is retracted radially inward with respect to an inner peripheral portion of the sleeve at a position rearward of the punch body; a punch rear portion protruding outward in the radial direction with respect to the suction recess portion, the suction recess portion being defined from a rear side; and a rear suction path communicating with the suction recess from a position rearward of the rear portion of the punch,

the injection filling process includes the following steps according to the position of the plunger or the elapsed time from the start of injection by the plunger:

a first step of starting suction from the suction recess through at least one of the suction port and the rear suction path after the pouring port of the sleeve is closed by the rear portion of the punch;

A second step of starting suction from a space in front of the punch body through the suction port after starting suction from the suction recess;

a third step of starting suction from the suction recess through the rear suction path or continuing suction from the suction port until suction from the suction port is stopped, before the suction port farthest forward from the pouring port among the 1 or more suction ports is closed by the rear portion of the punch and suction is stopped; and

and a fourth step of continuing suction from the suction recess through the rear suction path at least until the plunger reaches a switching position at which the plunger is switched from the speed control to the pressure control.

6. The casting method according to claim 5, wherein,

in the fourth step, suction from the suction recess through the rear suction path is continued until the filling of the molten metal into the cavity is completed.

7. The casting method according to claim 5 or 6, wherein,

the suction from the suction recess is continued over the front and rear sides of the position where the suction port farthest forward from the pouring port passes through the position where the suction is stopped by being closed by the rear part of the punch, so that a pressure difference smaller than the pressure difference between the front space and the outside air is continuously applied between the front space and the suction recess.

8. The casting method according to any one of claims 5 to 7, wherein,

the injection filling process comprises the following steps: a low-speed injection step of moving the plunger at a relatively low speed; and a high-speed injection step of moving the plunger at a relatively high speed,

in the low-speed injection step, the movement of the plunger is temporarily stopped or temporarily decelerated, and suction is performed from the suction recess through at least one of the suction port and the rear suction path over the front and rear sides of the stop or deceleration of the plunger.