JP2022055677A - Injection device of die cast machine and casting method - Google Patents

Abstract

To provide an injection device of a die cast machine capable of preventing the inflow of an open-air into a sucked sleeve and suppressing the rampage of a molten metal and a preceding molten metal, and a casting method.SOLUTION: An injection device 10 comprises a sleeve 11 and a plunger 20. The plunger 20 comprises a tip 21 and a rod 22. The sleeve 11 comprises two or more suction ports 101, 102 passing through the sleeve 11 over the inside and the outside and lining up in a cross direction D1. The plunger 20 comprises: a tip body 201 including at least a front end of the tip 21; a suction recessed part 203 rear than the tip body 201 and retreated to the inside in a radial direction to an inner circumferential part of the sleeve 11; a tip rear part 202 projected to the outside in a radial direction to the suction recessed part 203 and partitioning the suction recessed part 203 from the rear side; and a rear suction passage 204 communicating with the suction recessed part 203 from the rear than the tip rear part 202.SELECTED DRAWING: Figure 7

Description

The present invention relates to an injection device that injects molten metal into a cavity of a die casting machine by a plunger that can move forward and backward inside a sleeve, and a casting method by die casting.

A technique for sucking the inside of the sleeve is known in order to efficiently increase the degree of vacuum in the sleeve to which the molten metal is supplied and the cavity in which the molten metal is ejected by the plunger from the inside of the sleeve to suppress the occurrence of entanglement cavities in die-cast products. There is.
For example, Patent Document 1 describes a die casting machine that sucks the inside of a sleeve using a vacuum suction device.
Such die casting machines are equipped with first to fourth suction devices for sucking the inside of the sleeve and the cavity of the mold. A first suction device and a second suction device are used for suction inside the sleeve. The first suction device sucks the inside of the sleeve through an opening penetrating the sleeve in front of the pouring port into which the molten metal such as an aluminum alloy is injected. The second suction device sucks the inside of the sleeve from the rear side of the plunger tip through the suction pipe connected to the through hole that penetrates the flange provided in the plunger rod in the axial direction. The through hole of the flange communicates with the closed space formed between the constriction between the rear end of the plunger tip and the flange and the inner peripheral surface of the sleeve. According to Patent Document 1, by sucking the closed space with the second suction device, the front side of the tip is sucked through the gap between the outer peripheral surface of the tip and the inner peripheral surface of the sleeve.

According to Patent Document 1, when the plunger advances to a position where the pouring port is closed by the plunger tip after injecting the molten metal into the sleeve, first, through the opening of the sleeve, the first suction device causes the tip in the sleeve to be more than the tip. Aspirate the gas in the space in front. At this time, the gas in the cavity is also sucked through the space in front of the sleeve.
Then, when the plunger advances to the position where the opening of the sleeve is closed by the tip, the second suction device causes the second suction device to move from the rear of the tip to the closed space at the constricted portion and the gap between the tip and the sleeve to the tip. Start sucking forward. Further, when the plunger advances to a position where the opening of the sleeve is closed by the flange behind the tip, the third suction device initiates direct suction of the cavity. The fourth suction device is used for suction of the internal space of the base that supports the movable type.
According to the description of Patent Document 1, since the degree of vacuum in the sleeve is increased by using the first suction device and the second suction device together, it is possible to suppress the occurrence of entrainment cavities. Also, since the direct suction of the cavity is started after waiting for the opening of the sleeve to be closed, it is prevented that the degree of vacuum in the cavity becomes higher than the degree of vacuum in the sleeve, which prevents the hot water from becoming higher. Is suppressed.

Japanese Patent No. 5987674

When the molten metal in the sleeve goes wild due to the inflow of outside air into the sleeve, which has a negative pressure with respect to the atmospheric pressure due to suction, the opening for suction may be blocked due to the adhesion of droplets of the molten metal, or the molten metal component to the vacuum line. Accumulation of (molten residue) may cause a decrease in suction efficiency. In addition, there is a concern that entangled nests may occur due to the rampage of the molten metal.
"Rampaging of molten metal" means that, for example, the outside air blows in front of the tip from the rear end of the sleeve through the radial gap between the plunger and the sleeve, causing the molten metal to foam and scatter or the surface of the molten metal to shake violently. To tell.

In Patent Document 1, in order to efficiently evacuate the inside of the sleeve and the cavity, the inside of the sleeve is filled with suction by the first suction device, which has higher suction efficiency than the second suction device, before the suction by the second suction device. The pressure is reduced at once. Since the outside air flows in due to the pressure difference between the space in front of the tip given at this time and the outside air, it leads to the rampage of the molten metal.
In addition, in Patent Document 1, the suction by the first suction device and the suction by the second suction device are stopped at predetermined timings, but the outside air is in front of the tip while the suction in the sleeve is stopped. It will flow into the hot water and lead to the rampage of the molten metal.

Based on the above, it is an object of the present invention to provide an injection device for a die casting machine and a casting method capable of preventing the inflow of outside air into the sucked sleeve and suppressing the violence of the molten metal and the precipitating hot water.

INDUSTRIAL APPLICABILITY The present invention is an injection device including a sleeve to which molten metal is supplied inside and a plunger that can move forward and backward inside the sleeve, and ejects molten metal toward a cavity of a die casting machine by the plunger.
The plunger comprises a tip that pushes the molten metal in the sleeve forward and a rod that supports the tip from the rear.
The sleeve penetrates the sleeve inward and outward and comprises two or more suction ports arranged in the anteroposterior direction.
The plunger has a tip body that includes at least the front end of the tip, a suction recess that is retracted radially inward with respect to the inner peripheral portion of the sleeve behind the tip body, and a suction recess that protrudes radially outward with respect to the suction recess. It includes a tip rear portion that partitions the suction recess from the rear side, and a rear suction path that communicates with the suction recess from behind the tip rear portion.

The injection device of the die casting machine of the present invention includes a sleeve in which the molten metal is supplied to the inside and a plunger that can advance and retreat in the front-rear direction inside the sleeve, and the injection device injects the molten metal toward the cavity of the die casting machine by the plunger. It is a device.
The plunger comprises a tip that pushes the molten metal in the sleeve forward and a rod that supports the tip from the rear.
The sleeve penetrates the sleeve inward and outward and comprises one or more suction ports aligned in the anterior-posterior direction.
The plunger has a tip body that includes at least the front end of the tip, a suction recess that is retracted radially inward with respect to the inner peripheral portion of the sleeve behind the tip body, and a suction recess that protrudes radially outward with respect to the suction recess. It includes a tip rear portion that partitions the suction recess from the rear side, and a rear suction path that communicates with the suction recess from behind the tip rear portion.
The injection device comprises a control unit configured to control the operation of a suction system capable of suction through each of one or more suction ports and a rear suction path.
The control unit sucks from the suction recess through at least one of the suction port and the rear suction path after the sleeve pouring port is closed by the rear part of the tip, based on the position of the plunger or the elapsed time from the start of injection by the plunger. Is started, and after the suction from the suction recess is started, suction is started from the front space, which is the space in front of the chip body, through the suction port, and the suction port is the farthest from the pouring port among one or more suction ports. Before the suction of the suction port is stopped after the suction port is closed by the rear part of the tip, the suction from the suction recess is started through the rear suction path, or the suction is continued before the suction stop of the suction port, at least from the speed control. Continue until the plunger reaches the switching position to pressure control.

In the injection device of the die casting machine of the present invention, it is preferable that the control unit continues suction from the suction recess through the rear suction path until it detects the completion of filling the cavity with the molten metal.

In the injection device of the die casting machine of the present invention, assuming that the projected area of the suction port to the suction recess is A ₁ and the projected area of the rear suction path to the suction recess is A ₂ , A ₂ is the position of the plunger. It can be set to be equal to or higher _than the lower limit of A1 which changes periodically.
A ₁ corresponds to the projected area of the suction port when projected onto the suction recess from a direction orthogonal to the axial direction of the sleeve. A ₂ corresponds to the projected area of the rear suction path when projected from the axial direction of the sleeve onto the suction recess.

Further, the present invention is a casting method including an injection filling step of injecting and filling the molten metal into the cavity of the die casting machine by a plunger capable of advancing and retreating in the front-rear direction inside the sleeve to which the molten metal is supplied inside. The sleeve comprises a tip that pushes the molten metal in the sleeve forward and a rod that supports the tip from the rear, the sleeve penetrating the sleeve inward and outward, and one or more aligned in the anterior-posterior direction. With a suction port, the plunger has a tip body that includes at least the front end of the tip, a suction recess that is behind the tip body and retracts radially inward with respect to the inner circumference of the sleeve, and a suction recess that is radial with respect to the suction recess. Includes a rear end of the tip that projects outward of the tip and partitions the suction recess from the rear side, and a rear suction path that communicates with the suction recess from behind the rear of the tip.
The injection filling step is based on the position of the plunger or the elapsed time from the start of injection by the plunger from the suction recess through at least one of the suction port and the rear suction path after closing the sleeve pouring port by the rear of the tip. Of the first step of starting suction, the second step of starting suction from the front space, which is the space in front of the chip body through the suction port after the start of suction from the suction recess, and one or more suction ports. Before the suction stop of the suction port after closing by the tip rear part of the suction port farthest forward from the pouring port, the suction from the suction recess is started through the rear suction path, or the suction is performed before the suction stop of the suction port. It includes a third step of continuing from, and at least a fourth step of continuing suction from the suction recess through the rear suction path until the plunger reaches the switching position from speed control to pressure control.

In the fourth step in the casting method of the present invention, it is preferable to continue suction from the suction recess through the rear suction path until the completion of filling the cavity with the molten metal is detected.

In the casting method of the present invention, suction is continued from the suction recess before and after the position where the suction port farthest forward from the pouring port reaches the stop of suction through the closure by the rear part of the tip. It is preferable to give a small pressure difference between the front space and the suction recess with respect to the pressure difference between the front space and the outside air.

In the casting method of the present invention, the injection filling step 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. It is preferable to temporarily stop or temporarily decelerate, and to perform suction from the suction recess through at least one of the suction port and the rear suction path before and after stopping or decelerating the plunger.

According to the present invention, even if the suction port of the sleeve is closed by the tip due to the displacement of the plunger with respect to the sleeve and the vacuum suction from the suction recess through the suction port is interrupted, the suction path is rearward from the rear of the suction recess. Through this, vacuum suction from the suction recess can be continuously performed. By doing so, it is possible to continue to provide a decompression space to the suction recess located behind the space in front of the tip, so that the inflow of outside air into the space in front of the tip due to the pressure difference is prevented until the end of the injection filling process. , It is possible to suppress the rampage of molten metal and the generation of hot water. By preventing the inflow of outside air, it is possible to suppress the blockage of the path used for suction and perform vacuum suction stably and efficiently, which can contribute to the stability of quality and the improvement of productivity of the cast product.

It is a side view of the partial break which shows the injection apparatus which concerns on embodiment of this invention, and the die casting machine provided with it. It is a schematic diagram which shows the vacuum suction system provided in the die casting machine shown in FIG. 1. It is a figure which shows the sleeve and the plunger tip of the injection apparatus shown in FIG. (A) and (b) are graphs showing changes in the speed (solid line) and casting pressure (broken line) of the plunger in the injection filling step and the pressure increasing / holding step. (A) is a figure which shows the state which the projection area of a suction port to a suction recess is the maximum. (B) is a diagram showing a state in which the projected area of the suction port to the suction recess is the minimum. (C) is a diagram showing a state in which one of the suction ports is open to the atmosphere. It is a graph which shows that the projected area of a suction port to a suction recess changes according to the position (injection stroke) of a plunger. It is a figure for demonstrating an injection filling process, and (a) shows a plunger in the in-situ. (B) shows the position of the plunger to start the vacuum suction in the sleeve after the pouring port is closed by the rear part of the tip. (C) shows a state in which the suction port (# 1) closest to the pouring port is closed by the rear part of the tip. FIG. 7 is a diagram showing how the plunger advances in the order of (a) to (c) following FIG. 7 (c). At the time of (b), the suction port (# 2) farthest from the pouring port is closed by the rear part of the tip. (A) shows how the plunger advances toward the speed pressure switching position while continuing suction from the suction recess. (B) shows a state in which the plunger has reached the speed pressure switching command. (C) shows the plunger returned to the original position. It is a side view of the partial break which shows the injection apparatus which concerns on the modification of this invention, and the die casting machine provided with it. Only one suction port is formed on the sleeve. (A) shows a state in which the pouring port is closed by the rear part of the tip and suction can be started through each of the suction port and the rear suction path. (B) shows a state in which the suction port is closed and suction is continued only through the rear suction path.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
(Outline configuration of die casting machine)
The configuration of the die casting machine 1 will be briefly described with reference to FIGS. 1 to 3.
The die casting machine 1 includes a movable platen 3 in which a movable mold 2 and a product extrusion mechanism 2A are installed, a fixed platen 5 in which a fixed mold 4 is installed, and a machine base 6 that supports the movable platen 3 and the fixed platen 5. , A mold opening / closing / molding mechanism (not shown), an injection device 10 provided in the fixing plate 5 for injecting molten metal toward the cavity 7, a vacuum suction system 30 (FIG. 2), and operation of components of the die casting machine 1. It is provided with a control device 40 for controlling the above.

The die casting machine 1 uses a vacuum suction system 30 to suppress the generation of cavities (entanglement cavities) due to the entrainment of gas in the molten metal, and the cavity 7 and the sleeve 11 of the injection device 10 communicating with the cavity 7. Vacuum suction can be performed from the inside and from the inside.

A cavity 7 (product part) is formed between the movable mold 2 installed on the movable plate 3 which moves freely along the tie bar 3A and the fixed mold 4. At the boundary between the movable mold 2 and the fixed mold 4, a suction portion 8 that communicates with the cavity 7 and connects the vacuum pipe of the vacuum suction system 30 is provided. The suction unit 8 is provided in, for example, a Chill-Vent. Alternatively, the suction unit 8 may be a vacuum valve.
While the inside of the cavity 7 and the sleeve 11 is depressurized by the vacuum suction system 30, the injection device 10 injects molten metal such as aluminum or an aluminum alloy toward the cavity 7 and fills the cavity 7 for casting molding. The goods are manufactured.

(Configuration of injection device)
The injection device 10 includes a sleeve 11 to which molten metal is supplied inside, a plunger 20 that can move forward and backward with respect to the sleeve 11 inside the sleeve 11, and a drive source such as a hydraulic cylinder (not shown) that drives the plunger 20. There is.
Regarding the injection device 10, the front side F in the moving direction of the plunger 20 when injecting the molten metal, that is, the side F near 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 cylindrical body that extends linearly. The axial direction of the sleeve 11 coincides with the front-rear direction D1. The front side of the sleeve 11 penetrates the fixing plate 5 and communicates with the gap 41A of the mold sleeve 41 (FIG. 2) provided in the fixing mold 4.
The rear side of the sleeve 11 protrudes to the outside of the fixing plate 5 and extends horizontally toward the rear. A pouring port 110 into which the molten metal is injected by a ladle (not shown) is provided in the vicinity of the rear end 11B of the sleeve 11. The pouring port 110 penetrates the upper part of the peripheral wall 111 of the sleeve 11.
The hot water storage chamber is configured to include a space in front of the tip 21 in the sleeve 11 (front space 112) and a gap 41A of the mold sleeve 41. This hot water storage chamber communicates with the cavity 7 via the runner 42 and the gate 43.

A plurality of suction ports 101 and 102 penetrating the inside and outside of the sleeve 11 are formed on the peripheral wall 111 of the sleeve 11. Each of the suction ports 101 and 102 is individually connected to the vacuum pipe of the vacuum suction system 30 (FIG. 2).
The suction ports 101 and 102 are arranged in the front-rear direction D1 in front of the pouring port 110 on the peripheral wall 111, and both penetrate the peripheral wall 111 in the thickness direction. Hereinafter, they are referred to as a first suction port 101 (# 1) and a second suction port 102 (# 2) in order from the side closest to the pouring port 110. The first suction port 101 and the second suction port 102 are arranged on the upper part of the peripheral wall 111, avoiding the positions where they come into contact with the molten metal M.
According to 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 recess 203 behind the front space 112 from the positions distributed in the front-rear direction D1 in the injection filling step. Can be continuously sucked.

Three or more suction ports can be formed on the peripheral wall 111 according to the axial length of the sleeve 11, the degree of vacuum required inside the sleeve 11, and the like. For example, a third suction port and a fourth suction port can be added in front of the second suction port 102. These suction ports can be arranged in the front-rear direction D1 at an equal pitch or a variable pitch.
The first suction port 101 and the second suction port 102 are through holes having a circular cross section having the same diameter. However, the first suction port 101 and the second suction port 102 do not necessarily have the same diameter, and the shape of their openings does not matter. One or both of the first suction port 101 and the second suction port 102 may be formed in an oval shape long in the front-rear direction D1 or a long oval shape in the circumferential direction of the sleeve 11.

As will be described later, it is easy to secure a large opening area in the suction ports 101 and 102 of the sleeve 11 as compared with the opening area of the rear suction path 204 penetrating a part of the tip 21. By increasing the number of suction ports to increase the total opening area, the suction capacity can also be increased.

(Plunger)
The plunger 20 includes a tip 21 that pushes the molten metal in the sleeve 11 forward, and a rod 22 that supports the tip 21 from the rear.
The rod 22 is connected to a piston rod of a hydraulic cylinder (not shown) via a coupling (not shown). Due to the driving force of the hydraulic cylinder, the plunger 20 advances from the predetermined origin position toward the cavity 7 with a predetermined injection stroke to inject the molten metal, and when the injection is completed, the plunger 20 retracts to the origin position.

As shown in FIG. 3, the plunger 20 is located between the tip body 201 including at least the front end 20F of the tip 21, the tip rear portion 202 located on the rod 22 side, and the tip body 201 and the tip rear portion 202, and is a sleeve 11. It includes a suction recess 203 that forms a space 203A for preventing the inflow of outside air inside the peripheral wall 111, and a rear suction path 204 (# 3) that communicates with the suction recess 203 from behind the chip rear portion 202.

The inside of the chip 21 is typically provided with a cooling mechanism (not shown) for circulating a cooling medium such as water. With such a cooling mechanism, thermal expansion of the chip 21 can be suppressed.

The chip body 201 is a columnar member arranged inside the inner peripheral portion of the peripheral wall 111.
The chip rear portion 202 is a columnar member arranged behind the chip main body 201 and inside the inner peripheral portion of the peripheral wall 111. The tip rear portion 202 is attached to the rod 22 via the joint 23.
The same or different clearances are set between the chip main body 201 and the inner peripheral portion of the peripheral wall 111, and between the chip rear portion 202 and the inner peripheral portion of the peripheral wall 111, respectively.

The suction recess 203 is retracted inward in the radial direction of the chip main body 201 with respect to the inner peripheral portion of the peripheral wall 111. The suction recess 203 covers the entire circumference by the rear end 201B of the chip main body 201, the front end 202A of the chip rear portion 202, and the outer peripheral portion of the small diameter portion 203D whose diameter is smaller than the respective diameters of the chip main body 201 and the chip rear portion 202. It is partitioned. The molten metal M in the front space 112 basically does not enter the inside of the suction recess 203 beyond the gap between the tip main body 201 and the sleeve 11. Even if a small amount of the molten metal M enters the suction recess 203 from the front space 112, the space 203A in which the molten metal M does not exist is left over almost the entire area including the upper part of the suction recess 203.

The suction recess 203 provides a space 203A depressurized rearward of the chip body 201 by vacuum suction through at least one of the first and second suction ports 101 and 102 of the sleeve 11 and the rear suction path 204. By providing the decompressed space 203A behind the front space 112, the outside air flows into the front space 112, which has a negative pressure with respect to the outside atmosphere (outside air), through the gap between the tip 21 and the sleeve 11. You can prevent it from happening. This is because there is no difference between the pressure P1 in the space 203A of the suction recess 203 sucked by the vacuum suction system 30 and the pressure P2 in the front space ₁₁₂ , or even if there is a pressure difference, the pressure difference ₍ P). Since ₁ -P ₂ ) is sufficiently small compared to the difference (P ₀ -P ₂ ) between the atmospheric pressure P ₀ and the pressure P ₂ in the front space 112, the outside air flows into the front space 112 through the suction recess 203. This is because it is suppressed.
If the outside air flows into the front space 112 in which the molten metal M is stored, the molten metal M may foam and scatter, or the surface of the molten metal may violently shake. By preventing the inflow of outside air into the front space 112, it is possible to suppress such rampage of the molten metal M, and to avoid deterioration of the vacuum degree of the front space 112 due to the inflow of outside air, the pressure of the front space 112 is applied to the pressure of the cavity 7. Since it can be kept low, it is possible to prevent preceding molten metal. By preventing the hot water, it is possible to reduce product defects such as chipping, peeling, and stripping for shot blast.

In order to more sufficiently suppress the inflow of outside air from the space behind the chip rear portion 202 (rear space 113) into the suction recess 203, for example, a ring-shaped sealing member 205 may be provided on the chip rear portion 202, or the chip rear portion 202 may be provided. It is preferable that a sealant is filled between the outer peripheral portion of the wall and the inner peripheral portion of the peripheral wall 111. The sealing member 205 and the sealing agent can also be provided on the outer peripheral portion of the chip main body 201. The lubricant supplied to the chip 21 in the casting process also contributes to sealing between the outer peripheral portion of the chip 21 and the inner peripheral portion of the sleeve 11.

The rear suction path 204 extends rearward from the suction recess 203 via the tip rear portion 202 and is connected to the vacuum pipe of the vacuum suction system 30. The rear suction path 204 is connected to, for example, a through hole 204A that penetrates the chip rear portion 202 in the axial direction at the upper portion of the chip rear portion 202 and communicates with the space 203A, and a space behind the chip rear portion 202 (the space behind the chip rear portion 202). The rear space 113) includes a suction pipe 204B extending rearward along the rod 22. The rear space 113 is an atmospheric pressure and corresponds to an outside air space. The suction pipe 204B is connected to the vacuum pipe of the vacuum suction system 30 so as to allow a relative displacement in the front-rear direction D1 due to the advance / retreat of the plunger 20. The rear suction path 204 is not open to the atmosphere regardless of the position of the plunger 20. The suction ports 101 and 102 are open to the atmosphere depending on the position of the plunger 20.

The rear suction path 204 does not necessarily have to include the through hole 204A of the chip rear portion 202, and may be configured to include, for example, a groove formed at the upper end of the chip rear portion 202.
Further, the joint 23 or the rod 22 may be formed with a through hole as a part of the rear suction path 204 instead of the suction pipe 204B.
Further, there may be two or more rear suction paths 204 communicating with the space 203A (see, for example, FIG. 7A).

The chip 21 may be assembled from a plurality of members, or may be integrally formed by cutting a single member or the like. For example, the chip 21 can be assembled from a member corresponding to the chip main body 201, a member corresponding to the small diameter portion 203D, and a member corresponding to the chip 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 hot water pouring device (not shown) according to the manufacturing conditions, thereby molding, pouring, and injecting filling. A series of procedures including steps such as pressure boosting / holding, cooling, mold opening, product removal, mold release agent supply to the mold, plunger retreat, and lubricant supply to the chip 21 under a predetermined cycle time. Repeat.

The control device 40 drives and controls the hydraulic cylinder coupled to the plunger 20 while detecting the position of the plunger 20 by the position detecting unit 20S in the process of injection filling and the retracting of the plunger. By the control, the plunger 20 is controlled to a predetermined moving speed.
Further, the control device 40 controls the operation of the on-off valve 313 and the vacuum valve 30V of the vacuum suction system 30. For the control, the position of the plunger 20 detected by the position detection unit 20S is used.

As the position detection unit 20S, for example, it is preferable to use a linear encoder provided on the piston rod of the hydraulic cylinder coupled to the rod 22 of the plunger 20.
In addition, the position of the plunger 20 can be detected by using a switch lever provided on the rod 22 and a plurality of limit switches operated by the switch lever.

4 (a) and 4 (b) show an example of the pattern of the forward speed of the plunger 20 in the injection filling step S10. In FIGS. 4A and 4B, the casting pressure, which is the pressure applied to the molten metal through the plunger 20 by a hydraulic cylinder (not shown), is shown by a broken line.
In the injection filling step S10, the low-speed injection step S11 for advancing the plunger 20 from the original position in the low-speed range and the advancing speed of the plunger 20 to the high-speed range in the middle of the injection stroke are increased, and the molten metal M is transferred from the sleeve 11 by the tip 21. The high-speed injection step S12 of extruding and injecting into the cavity 7 is included.
When the low-speed injection step S11 is performed from the start of advancing the plunger 20 to, for example, the time when the molten metal M reaches the gate 43 via the runner 42, the low-speed injection step S11 shifts 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 constant as shown by the alternate long and short dash line in FIG. 4A, but the movement of the plunger 20 is temporarily shown by the solid line in FIG. 4A. The plunger 20 may be stopped for the stop period t1 or the plunger 20 may be temporarily decelerated for the deceleration period t2 as shown in (b). Before and after stopping or decelerating the plunger 20, the first suction port is parallel to, or not necessarily parallel to, suction from the front space 112 using the first suction port 101 and the second suction port 102. It is preferable to perform suction from the suction recess 203 through at least one of the 101 and the second suction port 102 and the rear suction path 204.
Here, "before and after" of the stop or deceleration means that the suction recess 203 is continuously sucked from before the start of the stop or deceleration to after the end of the stop or deceleration. To tell.

In order to prevent the inflow of outside air into the front space 112, it is preferable to continue suctioning at least the suction recess 203 of the front space 112 and the suction recess 203 as much as possible throughout the injection filling step S10.
According to the stop or deceleration of the plunger 20 in the injection filling step S10, vacuum suction is performed even if the axial length of the sleeve 11 is short with respect to the forward speed of the plunger 20 and the degree of vacuum required for the front space 112. Sufficient time can be secured to achieve the required degree of vacuum.

After increasing the speed of the plunger 20 to the high speed range, the control device 40, for example, based on the signal of the position detection unit 20S that detects the arrival of the plunger 20 at the speed pressure switching position (VP (Velocity Pressure) switching position), the plunger 20. The speed control based on the speed of 20 is switched to the pressure control (pressure holding control / pressure increasing control) based on the pressure of the molten metal in the cavity 7, and the process shifts to the pressure increasing / holding pressure step S20.
After that, when the molten metal in the cavity 7 is sufficiently solidified while being maintained at the specified casting pressure through an increase in the casting pressure, the movable platen 3 is moved to open the molds 2 and 4. When the molds 2 and 4 are opened, the product is pushed out from the cavity 7 by driving the product extrusion mechanism 2A, so that the product can be taken out from the molds 2 and 4.

While the temperature of the molten metal injected into the cavity 7 is high, the pressure is increased and the high pressure is propagated to every corner of the cavity 7 to compress and crush the air entrained in the molten metal. Immediately after the filling is completed, it is desired to shift to the pressure increasing / holding step S20. Therefore, the time required for the response of the valve of the hydraulic circuit including the hydraulic cylinder coupled to the plunger 20 and the hydraulic oil is expected, and the speed pressure switching position is the filling in which the molten metal has been filled in the cavity 7 in the injection stroke of the plunger 20. It is set to a position behind the completed position by the set length.

(Vacuum suction system)
An example of the configuration of the vacuum suction system 30 will be described with reference to FIG. The vacuum suction system 30 is provided with a vacuum pump 31, a pressure gauge 32A, a vacuum tank 32 in which the inside is depressurized by the operation of the vacuum pump 31, a first suction port 101, a second suction port 102, and a rear suction path. A sleeve suction system 30S that sucks the inside of the sleeve 11 through 204, a mold suction system 30M that directly sucks the cavity 7 through the suction portions 8 provided in the molds 2 and 4, and a pressurization for performing an air blow process. It is equipped with an air supply system 30P.

According to the example shown in FIG. 2, the sleeve suction system 30S and the mold suction system 30M also serve as the vacuum tank 32, but this is not the case, and the sleeve suction system 30S and the mold suction system 30M are separately used. It may be configured.

The mold suction system 30M includes a vacuum filter 301 for vacuum suction, a pressure gauge for detecting the pressure in the piping of the mold suction system 30M, and a compound meter in order from the upstream of the gas flow sucked from the cavity 7. A pressure detecting unit 302 such as a pressure sensor and a vacuum valve 303 for communicating the suction unit 8 with the vacuum tank 32 are provided.

The vacuum filter 301 suppresses the entry of fine droplets of molten metal, molten metal debris, which is a solidified piece, a mold release agent, dust, etc., which can be mixed in the sucked gas, into the mold suction system 30M. Similarly, the vacuum filter 311 provided in the sleeve suction system 30S also suppresses molten metal residue, lubricant, dust and the like from entering the sleeve suction system 30S.

When the vacuum valve 303 is opened, the gas in the cavity 7 is sucked from the suction unit 8 into the mold suction system 30M based on the pressure difference between the inside of the vacuum tank 32 and the cavity 7. At the time of 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 suction system 30S includes a vacuum valve 30V, a suction path 310 (# 1 to # 3) individually corresponding to the first suction port 101, the second suction port 102, and the rear suction path 204 of the sleeve 11, and these. It includes a merging / distributing unit 314 connected to the suction path 310.
Each suction path 310 includes a vacuum filter 311 for vacuum suction, a pressure detection unit 312 such as a pressure sensor for detecting the pressure in the suction path 310, in order from the upstream of the flow of gas sucked from the sleeve 11. An on-off valve 313 that opens or closes the suction path 310 is provided.

The vacuum valve 30V has a vacuum suction state in which each suction path 310 communicates with the vacuum tank 32, an air blow state in which each suction path 310 communicates with the pressure tank 322, and each suction path 310 in the vacuum tank 32 and the vacuum tank 32. It is possible to switch to a neutral state that does not communicate with any of the pressure tanks 322. When the vacuum valve 30V is in the vacuum suction state, vacuum suction is possible through the suction path 310 in the state where the open / close valve 313 is open.

By sending an open or close control command from the control device 40 to the on-off valve 313, the filling rate of the molten metal M in the front space 112, the pressure detected by the pressure detection unit 312, etc. can be adjusted according to the position of the plunger 20. Accordingly, all or part of the first suction port 101, the second suction port 102, and the rear suction path 204 can be communicated with the vacuum tank 32 to perform vacuum suction.
From the viewpoint of reducing the pressure inside the sleeve 11 to a sufficiently high degree of vacuum in a short time, it is preferable to use more suction ports 101 and 102 to secure a larger total opening area and perform vacuum suction. ..

When the opening / closing 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 with each other 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 that has flowed into the suction path 310 through the first suction port 101 merges with the flow from the other suction path 310 at the merging / distributing section 314 via the vacuum filter 311, the pressure detecting section 312, and the opening / closing valve 313, and further, the vacuum valve. After passing through 30V, it flows into the vacuum tank 32.
Similarly, for the suction path 310 (# 2) connected to the second suction port 102 and the suction path 310 (# 3) connected to the rear suction path 204, vacuum suction is performed by opening the corresponding opening / closing valve 313. can do.

In the present embodiment, the first suction port 101, the second suction port 102, the rear suction path 204, and each suction path 310 are also used as a path for performing air blow after the injection is completed. The molten metal residue can be removed from the suction path 310, the suction ports 101 and 102, and the rear suction path 204 by air blowing.
The pressurized air supply system 30P that performs air blow processing includes a compressed air source 321 that is a supply source of pressurized air, and a pressurized tank 322 that stores pressure inside by sending air by the compressed air source 321. ing.
Since the suction path 310 upstream of the merging / distributing section 314 (upstream during vacuum suction) is common between the time of vacuum suction and the time of air blow, the connection destination of the merging / distributing section 314 is connected to the vacuum tank 32 by the vacuum valve 30V. And by switching to the pressure tank 322, vacuum suction and air blow can be continuously performed.

The pressurized air supply system 30P is also used for the air blow of the mold suction system 30M performed after the mold is opened. Therefore, the vacuum valve 303 can switch the connection destination of the suction path of the mold suction system 30M between the vacuum tank 32 and the pressure tank 322. The flow rate of the air blow can be adjusted by a flow rate adjusting valve such as a globe valve (not shown) provided between the vacuum valve 303 and the pressure tank 322. The mold suction system 30M may be connected to a pressurized tank and a compressed air source different from the pressurized tank 322 and the compressed air source 321.

When the vacuum valve 30V is switched to the air blow, the pressurized air is distributed from the pressurized tank 322 to each suction path 310 by the merging / distributing unit 314, and the first suction port 101, the second suction port 102, and the rear suction path It spouts from 204 respectively. By sequentially switching the opening and closing of the opening / closing valve 313 corresponding to each of the first suction port 101, the second suction port 102, and the rear suction path 204 and performing air blow at one place, the positive pressure of the pressurized air can be obtained. In addition to being able to manage, the blocked state of each suction path 310 can be detected based on the measured value of the pressure detection unit 312. In addition, the flow rate of the air blow can be increased to enhance the cleaning effect. The flow rate of the air blow can be adjusted by a flow rate adjusting valve such as a globe valve (not shown) provided between the vacuum valve 30V and the pressure tank 322.

(Example of using the suction port of the sleeve and the rear suction path)
The relative positional relationship between each of the first suction port 101 and the second suction port 102 and the plunger 20 changes depending on the position of the plunger 20 with respect to the sleeve 11. For example, as shown in FIG. 3, when the second suction port 102 is open to the front space 112 in front of the chip main body 201, gas can be sucked from the front space 112 through the second suction port 102. ..
Since the pouring port 110 is open to the atmosphere, the pouring port 110 is closed by the tip main body 201 on the premise that suction is performed from the front space 112, so that the front space as a closed space is in front of the tip main body 201. 112 is formed. By performing the suction from the front space 112, the pressure of the cavity 7 communicating with the front space 112 can also be reduced.

Further, for example, when the first suction port 101 is located directly above the suction recess 203 of the chip 21, the space 203A can be sucked from the suction recess 203. As a premise that suction is performed from the suction recess 203, the pouring port 110 is closed by the tip rear portion 202, so that the suction recess 203 as a closed space is formed in front of the tip rear portion 202.

If the suction port (second suction port 102 of the present embodiment) farthest forward from the pouring port 110 is closed by the tip rear portion 202 and the suction from the suction recess 203 is completed, the front space is due to the pressure difference. It has been confirmed from the test results by the inventor that a hot spring in which the molten metal moves from 112 to the cavity 7 occurs. The cause of the occurrence of the first hot water is the deterioration of the degree of vacuum due to the inflow of outside air into the front space 112. Further, the suction port is closed by the tip main body 201 before the suction port farthest forward from the pouring port 110 is closed by the tip rear portion 202, so that the suction from the front space 112 is completed. Even so, it has been confirmed from the test results that the hot water can be suppressed if the suction from the suction recess 203 is continued.
In the present embodiment, since the second suction port 102 corresponds to the suction port farthest forward from the pouring port 110, suction from the front space 112 ends after the second suction port 102 is closed by the tip body 201. do. Further, after the second suction port 102 is closed by the tip rear portion 202, the suction from the suction recess 203 through the suction port of the sleeve 11 ends (END in FIG. 6). On the other hand, the suction of 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.
Based on the above, at least after the suction port, which is the farthest from the pouring port 110, is closed by the tip rear portion 202, if the suction of the suction recess 203 is continued using the rear suction path 204, the inflow of outside air is prevented and the molten metal is melted. It is effective in suppressing the rampage and the occurrence of hot water.

The capacity of vacuum suction performed through each of the first suction port 101 and the second suction port 102 of the sleeve 11 varies with the change in the projected area to the front space 112 and the suction recess 203, which are the suction targets.
For example, the second suction port 102 shown in FIG. 3 is substantially fully open with respect to the front space 112, and when the second suction port 102 is projected in the hole axis direction, the opening 102A of the second suction port 102 opens to the front space 112. Since it is projected over the entire area, the projected area to the front space 112 is the maximum. At this time, the suction capacity from the front space 112 through the second suction port 102 is maximum.
When the plunger 20 advances to the position shown by the alternate long and short dash line in FIG. 3, half of the opening 102A of the second suction port 102 is closed by the chip body 201, so that the second suction port 102 lacks half of the opening area. Is projected onto the front space 112. As the projected area decreases, so does the suction capacity.
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 chip main body 201, so that the projected area of the second suction port 102 on the front space 112 is large. It becomes the minimum, and at this time, the suction capacity from the front space 112 through the second suction port 102 becomes the minimum.

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

The rear suction path 204 always communicates with the suction recess 203 regardless of the position of the plunger 20 in the front-rear direction D1, and the projected area of the rear suction path 204 with respect to the suction recess 203 in the hole axis direction is the position of the plunger 20. It is constant regardless. Therefore, according to the rear suction path 204, a constant suction capacity can be obtained regardless of the position of the plunger 20.

As shown in FIGS. 5A and 5B, even if the diameters and pitches of the first suction port 101 and the second suction port 102 and the lengths of the front-rear direction D1 of each part 201 to 203 of the chip 21 are different. It is the same that the projected area of each suction port 101, 102 changes according to the position of the plunger 20, and the suction capacity changes accordingly. FIG. 5A shows a state in which the projected area A1 and the suction capacity are maximum with respect to the suction recess 203 through the _first suction port 101, and FIG. 5B shows _a state in which the projected area A1 and the suction capacity are the minimum. Is shown.
When the plunger 20 advances to the position shown in FIG. 5 (c) and the first suction port 101 is opened to the rear space 113 of the tip rear portion 202, that is, the atmosphere, the first suction port 101 to the suction path 310. In order to prevent the inflow of outside air, the opening / closing valve 313 corresponding to the first suction port 101 is closed.

The graph of FIG. 6 shows the change in the projected area of the suction port of the sleeve 11 to the suction recess 203 with respect to the ejection stroke (position in the front-rear direction D1) of the plunger 20. In the example shown in FIG. 6, four suction ports having the same diameter are arranged at equal pitches in the front-rear direction D1. The vertical axis of the graph shows the area ratio when the maximum projected area of the suction port to the suction recess 203 is 100%. Since each suction port of the sleeve 11 is sequentially closed as the plunger 20 advances, the area ratio is from 100%, which is the upper limit, to 20%, which is the lower limit in this example, depending on the position of the plunger 20. It changes periodically between. 20% is an example, and the lower limit of the area ratio changes depending on the diameter and pitch of the suction port, the length of each part 201 to 203 of the tip, and the like.

Even after the suction through the suction port of the sleeve 11 is completed, at least from the viewpoint of ensuring the minimum suction capacity before the end, in the example shown in FIG. 6, the opening corresponding to the lower limit area ratio of 20% or more. The area may be set to the rear suction path 204. The opening area of the rear suction path 204 corresponds to the projected area from the rear to the suction recess 203. That is, assuming that the projected area of the rear suction path 204 to the suction recess 203 is A ₂ , A ₂ is set to be equal to or larger than the lower limit of the projected area A ₁ of the suction port that periodically changes with respect to the position of the plunger 20. It is preferable to be done.
The opening area required for the rear suction path 204 can be set in consideration of the projected area of the suction port of the sleeve 11 on the suction recess 203, the pressure loss in the rear suction path 204, and the like.

Since the suction of the suction recess 203 through the rear suction path 204 can be performed regardless of the position of the plunger 20 even before the suction through the second suction port 102 of the sleeve 11 is completed, the suction is performed through the suction port of the sleeve 11. In parallel with the suction, the suction from the suction recess 203 through the rear suction path 204 can be continuously performed. By doing so, it is possible to strengthen the suppression of the inflow of outside air before the end of suction through the second suction port 102.

(Vacuum suction of sleeve)
Hereinafter, an example of the procedure for vacuum suction of the sleeve 11 in the injection filling step will be described with reference to FIGS. 7 to 9.
The control device 40 drives a hydraulic cylinder (not shown) to control the plunger 20 to a predetermined speed, and opens / closes each opening / closing valve 313 of the vacuum suction system 30 based on the position of the plunger 20 detected by the position detection unit 20S. do.

The plunger 20 shown in FIG. 7A is stopped at the in-situ position _X0 . The in-situ position X ₀ is set, for example, at the position of the rear end 110B of the pouring port 110.
When the plunger 20 is advanced from the original position _X0 and the front end 202A of the tip rear portion 202 reaches the position of the front end 110A of the pouring port 110, the pouring port 110 is closed by the tip rear portion 202. After the pouring port 110 is closed, both the suction recess 203 and the front space 112 are partitioned as a closed space, so that vacuum suction can be started from each of the suction recess 203 and the front space 112. Immediately after the pouring port 110 is closed, suction can be started through the rear suction path 204. Further, if even a part of the suction recess 203 is connected to the first suction port 101, it is possible to start suction through the first suction port 101.
In the control example shown in FIGS. 7 to 9, two rear suction paths 204 are installed in the rear portion 202 of the chip. These rear suction paths 204 are connected to the same suction path 310 of the vacuum suction system 30 (FIG. 2).

Here, in order to prevent the inflow of outside air, the suction start through the second suction port 102 is performed after the suction start through the suction recess 203 (recessed suction step s01 and front space suction step s02). The suction of the suction recess 203 can be performed through at least one of the first suction port 101 and the rear suction path 204. That is, at the same time as the control device 40 issues a control command for opening the open / close valve 313 corresponding to at least one of the first suction port 101 and the rear suction path 204, or after the control command is issued, the second suction is performed. A control command is issued to open the open / close valve 313 corresponding to the port 102. Then, when the decompression of the front space 112 is started, the decompression of the suction recess 203 is also started, so that the outside air does not flow into the front space 112 immediately after the decompression of the front space 112 based on the pressure difference from the atmospheric pressure. Can be prevented.

In the example shown in FIG. 7B, the position of the plunger 20 where the front end 202A of the tip rear portion 202 exceeds the front end 110A of the pouring port 110 and reaches the rear end 101A of the _first suction port 101 is set to the vacuum start position X1. ing.
Regarding the relative positions of the sleeve 11 and the plunger 20, the points of interest are shown by enclosing them in a broken line circle. Suction from the suction recess 203 through the first suction port 101 or the second suction port 102 is indicated by a solid line arrow, suction from the suction recess 203 through the rear suction path 204 is indicated by a broken line arrow, and the second suction port 102. The suction from the anterior space 112 through is indicated by the arrow of the two-point chain line. Further, the state in which the outside air tries to flow forward from the rear space 113 through the gap between the tip 21 and the sleeve 11 is indicated by the arrow of the alternate long and short dash line. The same applies to the following figures.
During vacuum suction from the suction recess 203 and the front space 112, the outside air that has flowed forward through the gap between the tip 21 and the sleeve 11 is sucked into the suction path 310 through the suction ports 101 and 102 or the rear suction path 204. To.

As shown in FIG. 7B, due to the mutual relationship between the diameters and pitches of the first suction port 101 and the second suction port 102, the lengths of the portions 201 to 203 of the tip 21, and the like, directly above the suction recess 203. There is a first suction port 101, and the opening of the first suction port 101 is projected onto the suction recess 203 over the entire area of the opening without being blocked by the chip main body 201 or the tip rear portion 202. .. Further, since the second suction port 102 is located in front of the chip main body 201, the second suction port 102 is opened to the front space 112 over the entire area of the opening. Therefore, suction can be performed from the suction recess 203 and the front space 112 with the maximum suction efficiency through the first suction port 101 and the second suction port 102. At the same time, suction from the suction recess 203 through the rear suction path 204 is also performed, so that 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 the inflow of outside air. At this time, the degree of vacuum in the front space 112 can be further sufficiently increased by temporarily stopping or decelerating the advancement of the plunger 20. Since the vacuum degree of the front space 112 is kept higher than the vacuum degree of the cavity 7, and the outside air does not flow into the front space 112 due to the suction of the suction recess 203, the hot water is prevented. The direct vacuum suction from the cavity 7 can be performed at an appropriate timing after the mold is fastened by the mold suction system 30M.

Subsequently, as shown in FIG. 7 (c), when the plunger 20 advances to a position where the front end 202A of the tip rear portion 202 reaches the front end of the first suction port 101, the tip main body 201 is directly below the second suction port 102. The tip rear portion 202 is located directly below the first suction port 101. That is, since the first suction port 101 and the second suction port 102 correspond to the closed state, the suction efficiency is reduced. Prior to opening the first suction port 101 to the atmosphere by further advancing the plunger 20, the control device 40 issues a command to close the opening / closing valve 313 corresponding to the first suction port 101. Since the closing operation of the opening / closing valve 313 is delayed with respect to the occurrence of the closing command, the chip body 201 and the sleeve 11 are used until the opening / closing valve 313 corresponding to the first suction port 101 is actually closed after the closing command is generated. In addition to the suction by the second suction port 102 through the gap between the two, the suction by the first suction port 101 through the gap between the tip rear portion 202 and the sleeve 11 can be continued.
The thin solid line shown in FIG. 7 (c) indicates that the suction is about to end due to the closing command to the opening / closing valve 313 corresponding to the first suction port 101.

As shown in FIG. 8A, when the plunger 20 advances to a position where the rear end 202B of the tip rear portion 202 reaches the rear end of the first suction port 101, the first suction port 101 communicates with the rear space 113 and enters the atmosphere. Be released. The opening / closing valve 313 corresponding to the first suction port 101 is already closed, and the suction through the first suction port 101 is stopped. Therefore, the outside air does not flow into the suction path 310 from the first suction port 101. At this time, since the suction recess 203 and the second suction port 102 are communicated with each other, the outside air from the rear to the front space 112 is continuously provided to the decompression space 203A behind the front space 112 by suction through the suction recess 203. Can be prevented from flowing in.

Then, as shown in FIG. 8B, when the plunger 20 advances to a position where the front end 202A of the tip rear portion 202 reaches the front end of the second suction port 102, the tip rear portion covers the entire projection range of the second suction port 102. Since 202 is present, the suction efficiency is lowered by closing the second suction port 102. Prior to opening the second suction port 102 to the atmosphere by further advancing the plunger 20, the control device 40 issues a command to close the opening / closing valve 313 corresponding to the second suction port 102. After the closing command is issued, suction by the second suction port 102 can be continued until the opening / closing valve 313 corresponding to the second suction port 102 is actually closed. Suction through the second suction port 102 is indicated by a thin solid arrow as it is scheduled to end.
The displacement amount of the plunger 20 from FIG. 7 (c) to FIG. 8 (b) is the sum of the dimension L1 between the first suction port 101 and the second suction port 102 and the diameter L2 of one suction port. Corresponds to the length. When other suction ports are lined up in the front-rear direction D1 in front of the second suction port 102, the procedure corresponding to FIGS. 7 (c) and 8 (a) is performed the number of times according to the number of suction ports. Repeated.

When the plunger 20 advances to a position where the second suction port 102 is opened to the atmosphere as shown in FIG. 8 (c) after closing the second suction port 102 shown in FIG. 8 (b), the second suction port has already been sucked. Since the opening / closing valve 313 corresponding to the port 102 is closed and the suction through the second suction port 102 is stopped, the outside air does not flow into the suction path 310 from the second suction port 102. At this time, since there is no other suction port in front of the second suction port 102, the suction means from the suction recess 203 is secured only by the rear suction path 204. In order to prevent the inflow of outside air into the front space 112 by suction from the suction recess 203, suction through the rear suction path 204 is started at least before the suction of the second suction port 102, which is the farthest from the pouring port 110, is stopped. (Backward suction step s03). The suction start through the rear suction path 204 may be started when the second suction port 102 shown in FIG. 8B is closed.
In this example, the suction of the suction recess 203 is started from the vacuum start position shown in FIG. 7B through the rear suction path 204, and the suction of the suction recess 203 is started before and after the suction stop of the second suction port 102. Is continued by suction through the posterior suction path 204. Therefore, before and after the suction stop of the second suction port 102, there is a small pressure difference (P 0 −P 2) between the front space 112 and the suction recess 203 with respect to the pressure difference (P ₀ −P ₂ ) between the front space 112 and the outside air. P1 _{- P2} ) is given.

The control device 40 moves the plunger 20 from the original position at a low speed, then switches the forward speed to a high speed, pushes the molten metal M out of the sleeve 11 by the tip 21, and ejects the molten metal M into the cavity 7 via the mold sleeve 41 (FIG. FIG. 9 (a)). The control device 40 changes the pressure based on the pressure of the molten metal in the cavity 7 from the speed control based on the speed of the plunger 20 based on the signal of the position detection unit 20S that detects the arrival of the chip body 201 at the speed pressure switching position _XVP . Switch control to control. Along with this, the process shifts from the injection filling step S10 to the pressure increasing / holding step S20.
Suction from the suction recess 203 through the rear suction path 204 is continued by keeping the opening / closing valve 313 corresponding to the rear suction path 204 open, at least until the tip body 201 reaches the velocity pressure switching position _XVP . (Recessed suction continuation step s04).

By suction from the suction recess 203, it is possible to prevent the inflow of outside air into the voids where the molten metal is present even at the end of the injection filling step, thereby suppressing the rampage of the molten metal and the entrainment of gas in the molten metal. From the start of the vacuum in the sleeve 11 shown in FIG. 7B to the end of the injection filling process, the inflow of outside air is prevented by suction from the suction recess 203, so that the generation of entrainment cavities and hot water is suppressed. At the same time, vacuum suction can be performed stably and efficiently by suppressing blockage of the suction path 310 and the like due to the inflow of molten metal residue together with the outside air. Therefore, it can contribute to the quality stability and productivity improvement of the cast product.

The tip 21 exceeds the velocity / pressure switching position _XVP shown in FIG. 9B and fills the cavity 7 while pushing the molten metal. As shown in FIGS. 4A or 4B, while the plunger 20 is advancing in the high-speed injection step S12, a casting pressure balanced with the flow resistance at the gate 43 is generated, but the molten metal over the entire cavity 7 is generated. With the completion of filling, the plunger 20 is stopped, the casting pressure is rapidly increased, and the process shifts to the pressure increasing / holding step S20. In the pressure increasing / holding step S20, after the casting pressure is further increased, the molten metal is solidified while maintaining the predetermined value. The tip 21 finally stops at a position advanced by the amount of shrinkage caused by the solidification of the molten metal.
When the signal of the position detection unit 20S for detecting the arrival of the chip main body 201 at the speed / pressure switching position _XVP is generated, the control device 40 issues a control command to close the opening / closing 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.

When the speed / pressure switching position _XVP is reached, the sleeve 11 in front of the tip 21 is already filled with the molten metal (the molten metal filling rate in the sleeve 11 is 100%), so that there is no void in the front space 112. .. Even in this state, if the outside air flows from the rear to the front of the tip 21, there is a risk of the molten metal being blown toward the cavity 7 by the outside air, so that the sleeve 11 is filled even after the molten metal is filled. It is meaningful to prevent the inflow of outside air until just before the completion.
In the above control example, a signal indicating the arrival of the plunger 20 at the speed pressure switching position X _VP close to the position of the plunger 20 at the completion of filling (filling completion position X _FC ) is used for stopping the suction from the suction recess 203. .. As a result, prior to the completion of filling, suction is continued through the suction recess 203 at least until the plunger 20 reaches the speed pressure switching position _XVP , so that the movement of the molten metal to the cavity 7 due to the inflow of outside air is suppressed and the hot water is first hot. It is possible to suppress the deterioration of casting quality due to.

If the suction from the suction recess 203 is continued until the filling is completed or just before the filling is completed beyond the velocity pressure switching position _XVP , the leading hot water is no longer at risk until the filling is completed. Is more preferable because it can be prevented more reliably. After the filling is completed, it is more preferable to immediately shift to increasing the pressure while the molten metal temperature is high because the air is compressed and crushed by the pressure propagation over the entire cavity 7 to reduce the cavities.
Therefore, not limited to the above control example, the control device 40 sucks through the rear suction path 204 when the completion of filling is detected, for example, based on the casting pressure after the plunger 20 reaches the speed pressure switching position _XVP . It is preferable to stop the suction from the recess 203.

The casting pressure (FIGS. 4A and 4B) 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. Therefore, the control device 40 can detect the completion of filling, for example, by applying a threshold value to the magnitude or increase rate of the casting pressure. Alternatively, the completion of filling can be detected by the arrival of the plunger 20 at the filling completion position X _FC (FIG. 9B) detected by the position detecting unit 20S.
If the completion of filling is detected based on the casting pressure or the position of the plunger 20, the control device 40 sends a closing command to the opening / closing valve 313 corresponding to the rear suction path 204. Here, in consideration of the time required for the response of the on-off valve 313, the threshold value applied to the casting pressure is adjusted to a lower side, or instead of the filling completion position X _FC , only the set length is set from the filling completion position X _FC . It is also preferable to adopt the position X _FC ′ immediately before the completion of filling, which is located in front (rear).

The control device 40 switches the vacuum valve 30V to an air blow with all the on-off valves 313 closed. First, by sequentially opening the opening / closing valves 313 corresponding to the first suction port 101 and the second suction port 102, pressurized air is ejected from each of the first suction port 101 and the second suction port 102, and the suction path 310 The molten metal residue can be removed from the suction ports 101 and 102. The molten metal residue that has fallen into the sleeve 11 is discharged to the rear end of the sleeve 11 by the tip 21 as the plunger 20 retracts.

Cleaning of the rear suction path 204 and the suction recess 203 by air blow can be performed, for example, with the plunger 20 returned to the in-situ position as shown in FIG. 9 (c). At this time, the suction recess 203 is exposed behind the sleeve 11. Therefore, the molten metal residue removed from the suction recess 203 by the pressurized air ejected forward from the rear suction path 204 falls on the outside of the sleeve 11, so that the molten metal residue can be prevented from entering the inside of the sleeve 11.

In the sleeve vacuum suction control described above, the opening / closing valve 313 is opened / closed based on the position of the plunger 20, but instead of the position of the plunger 20, at the reference time, for example, at the start of movement of the plunger 20 from the original position. The opening / closing valve 313 can also be opened / closed based on the elapsed time from (at the start of injection).

(Modified example of the present invention)
Unlike the above embodiment, the sleeve 11 of the injection device 10-2 according to the modified example of the present invention shown in FIG. 10 is formed with only one suction port 101. Except for this point, 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 in the above embodiment.
The tip 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 open, suction from the suction recess 203 through the rear suction path 204 is possible continuously.
Therefore, similarly to the control example described with reference to FIGS. 7 to 9 in the above embodiment, under the control of the control device 40, after the start of suction from the suction recess 203 through the rear suction path 204, the suction port 101 Suction from the anterior space 112 through is started (FIG. 11 (a)). Then, after the suction port 101 is closed by the tip rear portion 202, suction through the rear suction path 204 is started before the suction of the suction port 101 is stopped as shown in FIG. 11 (b). Suction from the suction recess 203 through the rear suction path 204 shall continue at least until the velocity pressure switching position is reached.
According to the above, as in the above embodiment, it is possible to prevent the inflow of outside air in front of the chip main body 201 continuously until the end of the injection filling process. It is possible to suppress the blockage of the 310 and to maintain the degree of vacuum in the sleeve 11 to suppress the generation of the hot water.

In addition to the above, as long as the gist of the present invention is not deviated, the configurations listed in the above embodiments can be selected or changed to other configurations as appropriate.
The plunger 20 may be provided with two or more suction recesses 203 at intervals in the front-rear direction D1. In that case, the suction recess and the rear portion of the chip are arranged in multiple stages behind the chip body. For example, the first chip rear portion 202-1, the first suction recess 203-1, the second chip rear portion 202-2, and the second suction recess 203-2 are arranged in this order from the rear end to the front end of the chip 21. .. Then, suction is performed from the first suction recess 203-1 through the first rear suction path 204-1 communicating with the first suction recess 203-1 from behind the rear portion 202-1 of the first chip, and the second suction recess is performed. Suction from the second suction recess 203-2 is performed through the second rear suction path 204-2 communicating with the second suction recess 203-2 from behind the tip rear portion 202-2. It is not always necessary to perform suction from all of the plurality of suction recesses 203, and it is sufficient if suction is performed from at least a part of the suction recesses 203. The rear suction paths provided to the plurality of suction recesses 203 may be independent of each other or may be partially common. In any case, by providing a plurality of suction recesses, even if some of the suction recesses are blocked by the adhesion of the molten metal residue, suction from the other suction recesses can be performed, so that the front It is possible to prevent the inflow of outside air into the space 112.

1,1-2 Die casting machine 2 Movable mold 2A Product extrusion mechanism 3 Movable plate 3A Tie bar 4 Fixed mold 5 Fixed plate 6 Machine base 7 Cavity 8 Suction part 10,10-2 Injection device 11 Sleeve 11B Rear end 20 Plunger 20F Front end 20S Position detection unit 21 Chip 22 Rod 23 Joint 30 Vacuum suction system 30M Mold suction system 30P Pressurized air supply system 30S Sleeve suction system 30V Vacuum valve 31 Vacuum pump 32 Vacuum tank 32A Pressure gauge 40 Control device (control unit)
41 Mold sleeve 41A Ventilation 42 Runner 43 Gate 101 First suction port 101A Rear end 102 Second suction port 102A Opening 110 Pouring port 110A Front end 110B Rear end 111 Peripheral wall 112 Front space 113 Rear space 201 Chip body 201B Rear end 202 Chip rear 202A Front end 202B Rear end 203 Suction recess 203A Space 203D Small diameter part 204 Rear suction path 204A Through hole 204B Suction tube 205 Seal member 301 Vacuum filter 302 Pressure detection unit 303 Vacuum valve 310 Suction path 311 Vacuum filter 312 Pressure detection unit 313 Open / close valve 314 Confluence / Distributor 321 Compressed air source 322 Pressurized tank A ₁ , A ₂ Projected area D1 Front-back direction L1 Dimension L2 Diameter M Molten metal P ₀ Atmospheric pressure P ₁ , P ₂ Pressure S10 Injection filling process S11 Low-speed injection process S12 High-speed injection process S20 Pressure boosting / holding process X ₀ Original position X ₁ Vacuum start position X _VP speed Pressure switching position X _FC Filling completion position X _FC ´ Filling completion position s01 Recessed suction step (1st step)
s02 Front space suction step (second step)
s03 Rear suction step (third step)
s04 Recessed suction continuation step (4th step)
t1 stop period t2 deceleration period

Claims (8)

An injection device including a sleeve to which molten metal is supplied to the inside and a plunger capable of moving forward and backward inside the sleeve, and ejecting the molten metal toward the cavity of the die casting machine by the plunger.
The plunger comprises a tip that pushes the molten metal in the sleeve forward and a rod that supports the tip from the rear.
The sleeve has two or more suction ports that penetrate the sleeve inward and outward and are aligned in the anteroposterior direction.
The plunger is
A chip body including at least the front end of the chip and
A suction recess behind the tip body and retracted radially inward with respect to the inner peripheral portion of the sleeve.
A tip rear portion that protrudes outward in the radial direction with respect to the suction recess and partitions the suction recess from the rear side.
A rear suction path communicating with the suction recess from behind the rear of the chip.
Injection device for die casting machines. An injection device including a sleeve to which molten metal is supplied to the inside and a plunger capable of moving forward and backward inside the sleeve, and ejecting the molten metal toward the cavity of the die casting machine by the plunger.
The plunger comprises a tip that pushes the molten metal in the sleeve forward and a rod that supports the tip from the rear.
The sleeve penetrates the sleeve inward and outward and comprises one or more suction ports aligned in the anterior-posterior direction.
The plunger is
A chip body including at least the front end of the chip and
A suction recess behind the tip body and retracted radially inward with respect to the inner peripheral portion of the sleeve.
A tip rear portion that protrudes outward in the radial direction with respect to the suction recess and partitions the suction recess from the rear side.
Includes a rear suction path that communicates with the suction recess from behind the tip.
The injection device is
A control unit configured to control the operation of a suction system capable of suction through each of one or more of the suction ports and the rear suction path is provided.
The control unit
Based on the position of the plunger or the elapsed time from the start of injection by the plunger.
After closing the pouring port of the sleeve by the rear part of the tip, suction from the suction recess is started through at least one of the suction port and the rear suction path, and after the suction start from the suction recess, the suction port is started. Through, suction from the front space, which is the space in front of the chip body, is started.
Suction from the suction recess through the rear suction path before the suction of the suction port is stopped after the suction port is closed by the tip rear portion of the suction port farthest forward from the pouring port among the one or more suction ports. The injection device of the die cast machine, which starts or continues the suction before the suction of the suction port is stopped, and continues at least until the plunger reaches the switching position from the speed control to the pressure control. The control unit
Suction from the suction recess through the rear suction path is continued until the completion of filling of the molten metal into the cavity is detected.
The injection device for the die casting machine according to claim 2. The projected area of the suction port on the suction recess is A ₁ .
Assuming that the projected area of the rear suction path to the suction recess is A ₂ .
A ₂ is set to be equal to or higher than the lower limit of A ₁ which changes periodically with respect to the position of the plunger.
The injection device for a die casting machine according to any one of claims 1 to 3. It is a casting method including an injection filling step of injecting and filling the molten metal into the cavity of a die casting machine by a plunger capable of advancing and retreating in the front-rear direction inside the sleeve to which the molten metal is supplied to the inside.
The plunger comprises a tip that pushes the molten metal in the sleeve forward and a rod that supports the tip from the rear.
The sleeve penetrates the sleeve inward and outward and comprises one or more suction ports aligned in the anterior-posterior direction.
The plunger has a chip body including at least the front end of the chip, a suction recess rearward behind the chip body and retracted radially inward with respect to the inner peripheral portion of the sleeve, and the diameter with respect to the suction recess. Includes a chip rear portion that projects outward in the direction and partitions the suction recess from the rear side, and a rear suction path that communicates with the suction recess from behind the chip rear portion.
The injection filling step is
Based on the position of the plunger or the elapsed time from the start of injection by the plunger.
A first step of initiating suction from the suction recess through at least one of the suction port and the rear suction path after the sleeve pouring port is closed by the tip rear portion.
After the start of suction from the suction recess, the second step of starting suction from the front space, which is the space in front of the chip body, through the suction port,
Suction from the suction recess through the rear suction path before the suction of the suction port is stopped after the suction port is closed by the tip rear portion of the suction port farthest forward from the pouring port among the one or more suction ports. The third step of starting or continuing the suction from before the suction of the suction port is stopped, and
A casting method comprising, at least, a fourth step of continuing suction from the suction recess through the rear suction path until the plunger reaches a switching position from speed control to pressure control. In the fourth step,
Suction from the suction recess through the rear suction path is continued until the completion of filling of the molten metal into the cavity is detected.
The casting method according to claim 5. By continuing suction from the suction recess before and after the position where the suction port farthest forward from the pouring port reaches the stop of suction through the closure by the rear part of the tip, the front space is continued. A small pressure difference is applied between the suction recess and the suction recess with respect to the pressure difference between the front space and the outside air.
The casting method according to claim 5 or 6. The injection filling step is
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 are included.
In the low speed injection step, the movement of the plunger is temporarily stopped or decelerated, and the suction is performed through at least one of the suction port and the rear suction path before and after the stop or deceleration of the plunger. Suction from the recess,
The casting method according to any one of claims 5 to 7.

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