JP7139262B2 - Injection unit and die casting machine - Google Patents

Description

The present invention relates to an injection device and a die casting machine comprising an injection piston connected to a plunger.

2. Description of the Related Art Conventionally, an injection device having an injection piston connected to a plunger is known (see, for example, Patent Document 1).

The aforementioned Patent Document 1 discloses an injection device that includes an injection cylinder, a piston accumulator connected to the injection cylinder via an oil passage, and a gas accumulator connected in series with the piston accumulator. The injection cylinder has an injection piston connected to the plunger.

Here, although not specified in Patent Document 1, there is generally known an injection device in which oil is stored at the bottom of a gas chamber to form a gas chamber between the oil and the piston of the piston accumulator. It is In such an injection device, the pressure in the gas chamber is adjusted by changing the amount of oil stored in the bottom of the gas chamber.

JP-A-11-10309

However, in a conventional injection device that forms a gas chamber between the oil stored in the bottom of the gas chamber and the piston, the amount of oil stored in the bottom of the gas chamber is hydraulically adjusted in order to adjust the pressure of the gas chamber. Since it is necessary to change the source indirectly, it takes a relatively long time to adjust the pressure in the gas chamber, and the pressure in the gas chamber cannot be adjusted accurately.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and one object of the present invention is to shorten the time required for adjusting the pressure in the gas chamber and to An object of the present invention is to provide an injection device and a die casting machine capable of accurately adjusting the pressure of.

To achieve the above object, the injection device according to the first aspect of the present invention provides an injection cylinder including an injection piston which is connected to a plunger and advances by increasing the pressure in the hydraulic chamber, and between the hydraulic chamber and the gas chamber. A piston accumulator including an oil piston for pressurizing the hydraulic chamber, a gas accumulator including a gas piston for pressurizing the gas chamber and connected in series with the piston accumulator, and attached to the gas piston. , a screw feed mechanism for moving the gas piston to the gas chamber side and to the side opposite to the gas chamber side; and an electric motor for driving the screw feed mechanism . The mechanism is configured to move the gas piston toward the gas chamber .

In the injection apparatus according to the first aspect of the present invention, with the configuration as described above, the gas chamber can be moved by simply moving the gas piston to the gas chamber side and the side opposite to the gas chamber side by means of the screw feed mechanism. Since the volume can be changed directly, the time required to adjust the pressure in the gas chamber can be shortened compared to the conventional method of adjusting the pressure in the gas chamber indirectly using oil. In addition, the pressure in the gas chamber can be adjusted with high accuracy. Here, when the pressure of the gas chamber is indirectly adjusted by oil as in the conventional art, the oil is likely to deteriorate because the oil and the gas filled in the gas chamber come into contact with each other. On the other hand, in the present invention, by using the screw feed mechanism, the pressure in the gas chamber can be adjusted without causing the problem of deterioration of the oil.

In the injection device according to the first aspect, it is preferable that the screw feed mechanism moves the gas piston toward the gas chamber in at least a part of the movement section of the injection piston when the injection piston is advanced. ing. With this configuration, the screw feed mechanism allows the gas piston to follow the oil piston as much as possible when injecting the molten metal. pressure drop can be suppressed. That is, it is possible to suppress deterioration of the pressure accumulation function of the accumulator (piston accumulator, gas accumulator).

In this case, preferably, in the final moving section of the injection piston when the filling of the mold with the molten metal is almost completed and the injection piston is moved forward to increase the injection pressure of the molten metal, It is configured to move the piston toward the gas chamber. With this configuration, the gas piston can be reliably caused to follow the oil piston by the screw feed mechanism in the pressure increasing section when the molten metal is injected, thereby preventing the volume of the gas chamber from increasing. , the pressure in the gas chamber can be prevented from dropping.

The injection apparatus according to the first aspect preferably further comprises a gas pressure gauge for measuring the pressure of the gas chamber, and based on the measurement result of the gas pressure gauge, the gas piston is moved by the screw feed mechanism before injection of the molten metal. It is configured to be moved to adjust the pressure in the gas chamber. With this configuration, the pressure in the gas chamber can be adjusted based on the measurement result of the gas pressure gauge before the injection of the molten metal, so the pressure in the gas chamber can be adjusted more accurately.

In this case, preferably, a hydraulic gauge for measuring the pressure in the hydraulic chamber is further provided, and based on the measurement results of the gas pressure gauge and the hydraulic gauge, the screw feed mechanism moves the gas piston during injection of the molten metal. It is configured. With this configuration, the gas piston can be moved based on the measurement results of the gas pressure gauge and the oil pressure gauge when the molten metal is injected. The piston can be moved with high precision. Therefore, it is possible to effectively suppress the decrease in the pressure of the gas chamber by suppressing an increase in the volume of the gas chamber.

In the injection device according to the first aspect, preferably, the screw feed mechanism includes a moving member attached to a surface of the gas piston opposite to the gas chamber side, and screwed to the moving member, and is driven by the electric motor. It includes a rod-shaped screw member that moves the moving member to the gas chamber side and to the side opposite to the gas chamber side by being rotationally driven. With this configuration, by attaching the moving member to the surface of the gas piston opposite to the gas chamber side, the gas piston can be moved without directly drilling a screw member hole in the gas piston to be moved. can be moved. Therefore, it is possible to suppress leakage of the sealed gas in the gas chamber from the gas piston.

In the injection device according to the first aspect, the electric motor is preferably a servomotor. With this configuration, the gas piston can be driven with high precision by the servomotor, so the pressure in the gas chamber can be adjusted with high precision.

A die casting machine according to a second aspect of the present invention comprises a die casting machine body including a sleeve and a plunger, and an injection device for moving the plunger of the die casting machine body, the injection device being connected to the plunger and increasing the pressure of a hydraulic chamber. a piston accumulator disposed between the hydraulic chamber and the gas chamber and having an oil piston for pressurizing the hydraulic chamber; and a gas piston for pressurizing the gas chamber. , a gas accumulator connected in series with the piston accumulator, a screw feed mechanism attached to the gas piston and moving the gas piston to the gas chamber side and the side opposite to the gas chamber side, and driving the screw feed mechanism and an electric motor for moving the gas piston toward the gas chamber side by the screw feed mechanism while keeping the volume of the gas chamber substantially constant .

With the die casting machine according to the second aspect of the present invention, the time required for adjusting the pressure of the gas chamber can be shortened in the same manner as the injection device according to the first aspect by configuring as described above. , the pressure in the gas chamber can be adjusted with precision.

According to the present invention, as described above, the time required for adjusting the pressure of the gas chamber can be shortened, and the pressure of the gas chamber can be adjusted with high accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic diagram which showed the whole structure of the die-casting machine provided with the injection device by one Embodiment. FIG. 5 is a diagram for explaining the operation in the pressure increasing section of the injection device according to one embodiment;

Embodiments embodying the present invention will be described below with reference to the drawings.

[Embodiment]
A configuration of a die casting machine 100 including an injection device 102 according to an embodiment will be described with reference to FIGS. 1 and 2. FIG.

In the following description, the moving direction of the movable mold M1 in the horizontal direction is assumed to be the X direction. The direction from the fixed mold M2 side to the movable mold M1 side in the X direction is defined as the X1 direction, and the opposite direction is defined as the X2 direction.

(Schematic configuration of die casting machine)
The die casting machine 100 shown in FIG. 1 is a horizontal molding machine that performs molding by horizontally reciprocating a movable mold M1 with respect to a fixed mold M2. The die casting machine 100 is configured to manufacture a molded product by injecting a liquid metal (molten metal) into a mold M (cavity) and solidifying it.

The die casting machine 100 includes a die casting machine body 101 and an injection device 102 . The die casting machine main body 101 includes a main body portion 111 to which the mold M is attached, and a mold clamping device 112 provided on the X1 direction side of the main body portion 111 .

The body portion 111 includes a movable die plate 111a to which the movable mold M1 is attached, and a fixed die plate 111b to which the stationary mold M2 is attached. Both the movable die plate 111a and the fixed die plate 111b have a flat plate shape with the X direction as the thickness direction.

The body portion 111 is provided with a plurality of (four) tie bars T having a round bar shape extending in the X direction and guiding the movement of the movable die plate 111a. A plurality of tie bars T are arranged near four corners of the movable die plate 111a and the fixed die plate 111b, respectively. A plurality of tie bars T are arranged outside the mold M so as to surround the mold M. As shown in FIG. The movable die plate 111a is configured to reciprocate in the X direction while being guided by tie bars T on the X1 direction side of the fixed die plate 111b.

The fixed die plate 111b is provided with a sleeve 113 and a plunger 114 for injecting into the mold M molten metal supplied by a pouring device (not shown). The plunger 114 is configured to be driven by the injection device 102 to reciprocate (advance and retreat) within the sleeve 113 in the X direction.

The mold clamping device 112 moves the movable die plate 111a in the X direction with respect to the fixed die plate 111b, thereby switching the die casting machine 100 between the mold clamping state and the mold open state (the moving mold M1 and the fixed mold M2 are predetermined). separated by a distance). As an example, the mold clamping device 112 is configured by a toggle mechanism.

The injection device 102 advances the plunger 114 and is in a mold clamping state (a state in which the movable die plate 111a and the fixed die plate 111b are close to each other and the movable mold M1 and the fixed mold M2 are in contact). It is configured to inject molten metal into the mold M (cavity). A detailed configuration of the injection device 102 will be described below.

(Structure of injection device)
The injection device 102 includes an injection cylinder 1, a hydraulic oil supply device 2, a piston accumulator 3, a gas accumulator 4, a screw feed mechanism 5, a servo motor 6 for driving the screw feed mechanism 5, and a controller 7. I have. The servomotor 6 is an example of the "electric motor" in the scope of claims.

Further, the injection device 102 includes an oil passage 8 a connecting the injection cylinder 1 and the piston accumulator 3 and a gas passage 8 b connecting the piston accumulator 3 and the gas accumulator 4 . That is, the injection cylinder 1 and the piston accumulator 3 are connected in series by the oil passage 8a. Moreover, the piston accumulator 3 and the gas accumulator 4 are connected in series by the gas passage 8b.

The injection device 102 is configured to advance the injection piston 12 of the injection cylinder 1 by supplying hydraulic oil to the injection cylinder 1 from the hydraulic oil supply device 2 . Thereby, the injection device 102 is configured to advance the plunger 114 connected to the tip (X1 direction end) of the injection piston 12 . At this time, the injection device 102 is configured to accumulate pressure by the piston accumulator 3 and the gas accumulator 4 so that the injection piston 12 is pushed in the forward direction (X2 direction) in order to accelerate the injection piston 12. there is

The injection device 102 adjusts the pressure (and volume) of the gas chamber G of the gas accumulator 4 by moving the gas piston 42 of the gas accumulator 4 by means of the screw feed mechanism 5 to adjust the state of pressure accumulation. It is configured.

<Structure of injection cylinder>
The injection cylinder 1 includes a cylindrical injection cylinder body 11 and an injection piston 12 provided within the injection cylinder body 11 .

The inside of the injection cylinder main body 11 functions as a moving space for the injection piston 12 . The injection piston 12 partitions the inside of the injection cylinder main body 11 into a space on the rod side (X1 direction side, that is, the plunger 114 side) and a space (hydraulic chamber Oa) on the head side (X2 direction side).

The hydraulic chamber O is provided across the injection cylinder 1 and the piston accumulator 3 . Therefore, the injection cylinder 1 side is referred to as the hydraulic chamber Oa, the piston accumulator 3 side is referred to as the hydraulic chamber Ob, and the hydraulic chamber Oa and the hydraulic chamber Ob are collectively referred to as the hydraulic chamber O. The hydraulic chamber Oa and the hydraulic chamber Ob communicate with each other via an oil passage 8a.

The hydraulic chamber Oa is provided with a hydraulic gauge 13 for measuring the pressure of the hydraulic chamber Oa (hydraulic chamber O). The measurement result of the oil pressure gauge 13 is acquired by the controller 7 and used for controlling the screw feed mechanism 5 by the controller 7 for driving the gas piston 42 of the gas accumulator 4 during injection of the molten metal.

The injection piston 12 is configured to move forward when the pressure in the hydraulic chamber Oa (hydraulic chamber O) is increased. The injection piston 12 has a rod-shaped rod portion 12a connected to the plunger 114, and a head portion 12b provided at the X2 direction end of the rod portion 12a. A tip (X1-direction end) of the injection piston 12 (rod portion 12a) is connected to the plunger 114 . Further, the head portion 12b divides the inside of the injection cylinder main body 11 into two spaces as described above. Note that FIG. 1 shows a state in which the head portion 12b is arranged at the end in the X2 direction, and the volume of the hydraulic chamber Oa is zero.

Here, during the injection of the molten metal, the movement section (stroke) of the injection piston 12 has three sections, a low-speed movement section, a high-speed movement section, and a pressure-increase section, from the start of forward movement to the stop. . The injection piston 12 moves forward at a relatively low speed (for example, 10 mm/s) under the control of the control section 7 in the low speed movement section. The injection piston 12 moves forward at a relatively high speed (for example, 50 mm/s) under the control of the control section 7 in the high-speed movement section. The injection piston 12 advances at an extremely low speed (sufficiently lower than the low speed movement region) under the control of the control unit 7 in the pressure increasing section. The pressure in the hydraulic chamber Oa (hydraulic chamber O) is controlled by the control unit 7 so as to increase in order of the low speed movement section, the high speed movement section, and the pressure increase section.

<Configuration of hydraulic oil supply device>
The hydraulic oil supply device 2 is connected to the oil passage 8a. The hydraulic fluid supply device 2 is configured to supply hydraulic fluid to the hydraulic chamber O (hydraulic chamber Oa) in order to move the injection piston 12 forward. The hydraulic oil supply device 2 includes a motor 21 and an oil pump 22 driven by the motor 21 .

The hydraulic oil supply device 2 supplies hydraulic oil under the control of the control unit 7 so that the pressure in the hydraulic chamber Oa (hydraulic chamber O) increases in the order of the low speed movement section, the high speed movement section, and the pressure increase section. Configured to adjust speed.

<Configuration of piston accumulator>
The piston accumulator 3 includes a tubular accumulator body 31 and an oil piston 32 provided inside the accumulator body 31 .

The inside of the accumulator main body 31 functions as a moving space for the oil piston 32 . The inside of the accumulator main body 31 is partitioned into a space (hydraulic chamber Ob) on the side of the injection cylinder 1 and a space (gas chamber Ga) on the side of the gas accumulator 4 by an oil piston 32 .

The gas chamber G is provided across the piston accumulator 3 and the gas accumulator 4 . Therefore, the piston accumulator 3 side is referred to as a gas chamber Ga, the gas accumulator 4 side is referred to as a gas chamber Gb, and the gas chambers Ga and Gb are collectively referred to as a gas chamber G. The gas chamber Ga and the gas chamber Gb communicate with each other through a gas passage 8b. A gas chamber G (gas chamber Ga, gas chamber Gb) is filled with nitrogen gas.

The accumulator main body 31 has a concave housing member 31a that houses the oil piston 32, and a lid member 31b that closes the opening of the housing member 31a. A gas passage 8b is connected to the bottom portion of the housing member 31a. The oil passage 8a is connected to the lid member 31b.

The oil piston 32 is configured to move forward (toward the injection cylinder 1 side) when injecting molten metal. The oil piston 32 is arranged between the hydraulic chamber Ob (hydraulic chamber O) and the gas chamber Ga (gas chamber G), and pressurizes the hydraulic chamber Ob (hydraulic chamber O).

<Configuration of gas accumulator>
The gas accumulator 4 includes a cylindrical accumulator body 41 and a gas piston 42 provided inside the accumulator body 41 .

The inside of the accumulator main body 41 functions as a moving space for the gas piston 42 . The inside of the accumulator body 41 is partitioned into a space (gas chamber Gb) on the piston accumulator 3 side and a space (atmosphere) on the screw feed mechanism 5 side by a gas piston 42 .

The accumulator main body 41 has a concave housing member 41a that houses the gas piston 42, and a lid member 41b that closes the opening of the housing member 41a. A gas passage 8b is connected to the bottom portion of the housing member 41a.

A through hole 41c extending in the moving direction of the gas piston 42 is formed in the cover member 41b. A later-described moving member 51 of the screw feed mechanism 5 is inserted through the through hole 41c. The through hole 41 c guides the movement of the moving member 51 that moves together with the gas piston 42 by contacting the inner surface of the moving member 51 of the screw feed mechanism 5 , which will be described later. Further, the through hole 41 c restricts the rotation of the moving member 51 with respect to the accumulator main body 41 by bringing the inner surface thereof into contact with the moving member 51 . As a result, the moving member 51 is prevented from rotating together with the ball screw member 52 of the screw feed mechanism 5, which will be described later. The ball screw member 52 is an example of the "screw member" in the claims.

The gas piston 42 pressurizes the gas chamber Gb (gas chamber G). The gas piston 42 is configured to be moved toward the gas chamber Gb by the screw feed mechanism 5 when the molten metal is injected. Further, the gas piston 42 is moved by the screw feed mechanism 5 to either the gas chamber Gb side or the side opposite to the gas chamber Gb when adjustment is required before injection of the molten metal. It is configured.

The gas chamber Gb is provided with a gas pressure gauge 43 for measuring the pressure of the gas chamber Gb (gas chamber G). The measurement result of the gas pressure gauge 43 is acquired by the control unit 7, and the screw feeding by the control unit 7 for driving the gas piston 42 of the gas accumulator 4 is performed during adjustment before injection of the molten metal and during injection of the molten metal. It is used to control the mechanism 5.

A gas supply unit 44 is provided in the gas chamber Gb. The gas supply unit 44 is configured to supply nitrogen gas to the gas chamber Gb.

<Structure of screw feed mechanism>
The screw feed mechanism 5 is attached to the gas piston 42 and is configured to move the gas piston 42 to the gas chamber G side and to the side opposite to the gas chamber G side. The screw feed mechanism 5 is configured to smoothly move the gas piston 42 within the accumulator main body 41 at a predetermined speed by means of a ball screw mechanism.

Specifically, the screw feed mechanism 5 includes a moving member 51 and a rod-shaped ball screw member 52 . The moving member 51 has a cylindrical rod tube 51a inserted through the through hole 41c of the gas accumulator 4, and a ball nut 51b fixedly attached to one end of the rod tube 51a.

The rod-shaped ball screw member 52 extends in the moving direction of the gas piston 42 . Ball screw member 52 is rotatably supported by bearing 53 . The ball screw member 52 is screwed onto the ball nut 51 b of the moving member 51 . The ball screw member 52 is configured to move (straight ahead) the moving member 51 toward the gas chamber Gb and to the opposite side to the gas chamber Gb by being rotationally driven by the servomotor 6 .

Rotation of the rod tube 51a (moving member 51) is restricted by being inserted into the through hole 41c. The moving member 51 (the other end of the rod tube 51a) is fixedly attached to the surface 42a of the gas piston 42 opposite to the gas chamber Gb side.

The moving member 51 is configured to move toward the gas chamber Gb via the ball screw member 52 when the ball screw member 52 rotates in a predetermined direction while the rotation is restricted. Conversely, the moving member 51 moves to the side opposite to the gas chamber Gb via the ball screw member 52 by rotating the ball screw member 52 in a direction opposite to the predetermined direction while the rotation is restricted. is configured as

<Structure of Driving Force Transmission Mechanism>
A driving force transmission mechanism K is provided between the screw feed mechanism 5 and the servomotor 6 to transmit the driving force of the servomotor 6 to the screw feed mechanism 5 .

The driving force transmission mechanism K includes a large-diameter pulley K1, a small-diameter pulley K2, and a timing belt K3.

The large-diameter pulley K1 is attached to one end of the ball screw member 52 . The small-diameter pulley K2 is attached to the rotary shaft of the servomotor 6. As shown in FIG. The timing belt K3 is stretched around the outer periphery of the large-diameter pulley K1 and the outer periphery of the small-diameter pulley K2. When the large-diameter pulley K1 is rotated by the servomotor 6, the ball screw member 52 is rotated together with the small-diameter pulley K2 via the timing belt K3. As a result, the gas piston 42 is moved.

The driving force transmission mechanism K is not limited to the above example, and may be configured to transmit the driving force of the servomotor 6 to the screw feed mechanism 5 using a plurality of gears without using a belt.

<Configuration of control unit>
The control unit 7 is configured to move the gas piston 42 to the gas chamber G side by the screw feed mechanism 5 in at least a part of the movement section of the injection piston 12 when advancing the injection piston 12 .

Specifically, the control unit 7 controls the final moving section (pressure increasing section) of the injection piston 12 when the injection pressure of the molten metal is increased by moving the injection piston 12 forward after filling the mold M with the molten metal is almost completed. (see FIG. 2)), the screw feed mechanism 5 is configured to move the gas piston 42 to the gas chamber G side while keeping the volume (pressure) of the gas chamber G substantially constant. In FIG. 2, the solid line indicates the injection piston 12, the oil piston 32, and the gas piston 42 at the start of the pressure increasing section, and the two-dot chain line indicates the injection piston 12 and the oil piston 32 at the end of the pressure increasing section. , the gas piston 42 is shown.

That is, the control unit 7 is configured to synchronize the movements of the gas piston 42 and the oil piston 32 at least in the pressure increasing section.

In the low-speed movement section and the high-speed movement section before the pressure increasing section, the control unit 7 keeps the volume (pressure) of the gas chamber G substantially constant, and moves the gas piston 42 by the screw feed mechanism 5. It may be configured to move toward the gas chamber G (configured to synchronize the movements of the gas piston 42 and the oil piston 32).

Keeping the volume of the gas chamber G substantially constant (synchronizing the movements of the gas piston 42 and the oil piston 32) means that the volume of the gas chamber Gb in the gas accumulator 4 is changed according to the movement of the gas piston 42. This is the case where the amount of decrease is substantially equal to the amount of decrease in the volume of the hydraulic chamber Ob in the piston accumulator 3 accompanying the movement of the oil piston 32 when the gas piston 42 moves. In this case, if the gas piston 42 and the oil piston 32 have the same cross-sectional area (the size of the cross section perpendicular to the direction of movement), the amount of movement of the gas piston 42 and the oil piston 32 will also be substantially the same. .

Based on the measurement results of the gas pressure gauge 43 and the oil pressure gauge 13, the control unit 7 is configured to move (advance) the gas piston 42 by the screw feed mechanism 5 when injecting the molten metal to move the injection piston 12 forward. It is In addition, based on the measurement result of at least one of the gas pressure gauge 43 and the oil pressure gauge 13, the control unit 7 moves (advances) the gas piston 42 by the screw feed mechanism 5 at the time of injection of the molten metal to move the injection piston 12 forward. ).

The control unit 7 is configured to adjust the pressure of the gas chamber G by moving the gas piston 42 with the screw feed mechanism 5 based on the measurement result of the gas pressure gauge 43 before injection of the molten metal. At this time, the control unit 7 may also control the gas supply unit 44 to adjust the pressure of the gas chamber G.

(Effect of Embodiment)
The following effects can be obtained in this embodiment.

In the present embodiment, as described above, the volume of the gas chamber G can be directly changed simply by moving the gas piston 42 to the gas chamber G side and to the side opposite to the gas chamber G side using the screw feed mechanism 5. Therefore, the time required for adjusting the pressure of the gas chamber G can be shortened compared to the conventional method of indirectly adjusting the pressure of the gas chamber G using oil. The pressure in chamber G can be adjusted with high accuracy. Here, when the pressure of the gas chamber G is indirectly adjusted by oil as in the conventional art, the oil and the gas filled in the gas chamber G come into contact with each other, so the oil is likely to deteriorate. On the other hand, in this embodiment, by using the screw feed mechanism 5, the pressure of the gas chamber G can be adjusted without causing the problem of oil deterioration.

In this embodiment, as described above, the gas piston 42 is moved toward the gas chamber G by the screw feed mechanism 5 in at least a portion of the movement section of the injection piston 12 when the injection piston 12 is advanced. It is configured. This allows the gas piston 42 to follow the oil piston 32 as much as possible by the screw feed mechanism 5 when injecting the molten metal. A decrease in G pressure can be suppressed. That is, it is possible to suppress deterioration of the pressure accumulation function of the accumulators (piston accumulator 3, gas accumulator 4).

In the present embodiment, as described above, when the mold M is substantially filled with the molten metal and the injection piston 12 is moved forward to increase the injection pressure of the molten metal, in the final movement section of the injection piston 12, gas The screw feed mechanism 5 is configured to move the gas piston 42 toward the gas chamber G while keeping the volume of the chamber G substantially constant. As a result, the gas piston 42 can be reliably caused to follow the oil piston 32 by means of the screw feed mechanism 5 in the pressure increasing section when the molten metal is injected, thereby preventing the volume of the gas chamber G from increasing. , the pressure in the gas chamber G can be prevented from decreasing.

In this embodiment, as described above, the gas pressure gauge 43 for measuring the pressure of the gas chamber G is further provided, and based on the measurement result of the gas pressure gauge 43, the gas piston is adjusted by the screw feeding mechanism 5 before injection of the molten metal. 42 is moved to adjust the pressure of the gas chamber G. As a result, the pressure in the gas chamber G can be adjusted based on the measurement result of the gas pressure gauge 43 before injection of the molten metal, so that the pressure in the gas chamber G can be adjusted more accurately.

In this embodiment, as described above, the oil pressure gauge 13 that measures the pressure in the hydraulic chamber O is further provided. , to move the gas piston 42 . As a result, when the molten metal is injected, the gas piston 42 can be moved based on the measurement results of the gas pressure gauge 43 and the oil pressure gauge 13, so that the screw feed mechanism 5 can be operated in accordance with the movement of the oil piston 32. The gas piston 42 can be moved precisely. Therefore, it is possible to effectively prevent the pressure of the gas chamber G from decreasing by suppressing the volume of the gas chamber G from increasing.

In the present embodiment, as described above, the screw feed mechanism 5 is screwed to the moving member 51 attached to the surface 42a of the gas piston 42 opposite to the gas chamber G side, and the moving member 51. , and a rod-shaped ball screw member 52 that is rotated by the servomotor 6 to move the moving member 51 to the gas chamber G side and to the side opposite to the gas chamber G side. Accordingly, by attaching the moving member 51 to the surface 42a of the gas piston 42 opposite to the gas chamber G side, the gas piston 42 can be moved without directly forming a hole for the ball screw member 52 in the gas piston 42. Piston 42 can be moved. Therefore, it is possible to suppress leakage of the sealed gas in the gas chamber G from the gas piston 42 .

In this embodiment, the servomotor 6 is provided as described above. As a result, the gas piston 42 can be driven accurately by the servomotor 6, so the pressure in the gas chamber G can be adjusted more accurately.

[Modification]
The embodiments disclosed this time should be considered illustrative and not restrictive in all respects. The scope of the present invention is indicated by the scope of the claims rather than the description of the above-described embodiments, and includes all modifications (modifications) within the scope and meaning equivalent to the scope of the claims.

For example, in the above-described embodiment, the screw feed mechanism of the present invention was exemplified by a ball screw mechanism, but the present invention is not limited to this. In the present invention, the screw feed mechanism may be configured by a screw mechanism having no ball members instead of the ball screw mechanism.

Further, in the above-described embodiment, an example in which the screw feed mechanism is driven under the control of the control unit has been shown, but the present invention is not limited to this. In the present invention, the operator may drive (operate) the screw feed mechanism without using the control section.

1 injection cylinder 3 piston accumulator 4 gas accumulator 5 screw feed mechanism 6 servo motor (electric motor)
12 Injection Piston 13 Oil Pressure Gauge 32 Oil Piston 42 Gas Piston 42a (On the Side Opposite to the Gas Chamber Side of the Gas Piston) 43 Gas Pressure Gauge 51 Moving Member 52 Ball Screw Member (Screw Member)
REFERENCE SIGNS LIST 100 die casting machine 101 die casting machine body 102 injection device 113 sleeve 114 plunger G, Ga, Gb gas chamber M mold O, Oa, Ob hydraulic chamber

Claims (8)

an injection cylinder connected to the plunger and including an injection piston that advances due to increased pressure in the hydraulic chamber;
a piston accumulator disposed between the hydraulic chamber and the gas chamber and including an oil piston for pressurizing the hydraulic chamber;
a gas accumulator including a gas piston for pressurizing the gas chamber and connected in series with the piston accumulator;
a screw feed mechanism attached to the gas piston for moving the gas piston to the gas chamber side and a side opposite to the gas chamber side;
and an electric motor that drives the screw feed mechanism ,
The injection device is configured to move the gas piston toward the gas chamber by the screw feed mechanism while maintaining the volume of the gas chamber substantially constant . 2. The gas piston according to claim 1, wherein said screw feed mechanism moves said gas piston toward said gas chamber in at least a part of said injection piston moving section when said injection piston is advanced. injection device. When the filling of the molten metal into the mold is almost completed, and the injection piston is moved forward to increase the injection pressure of the molten metal, the gas piston is moved by the screw feed mechanism in the final movement section of the injection piston. 3. The injection device according to claim 2, configured to move toward the gas chamber. Further comprising a gas pressure gauge for measuring the pressure of the gas chamber,
Claims 1 to 3, wherein the screw feed mechanism moves the gas piston to adjust the pressure of the gas chamber based on the measurement result of the gas pressure gauge before injection of the molten metal. The injection device according to any one of Claims 1 to 3. Further comprising a hydraulic gauge for measuring the pressure in the hydraulic chamber,
5. The injection device according to claim 4, wherein the screw feed mechanism moves the gas piston based on the measurement results of the gas pressure gauge and the oil pressure gauge during injection of the molten metal. The screw feed mechanism is
a moving member attached to a surface of the gas piston opposite to the gas chamber;
A rod-shaped screw member that is screwed to the moving member and that is rotated by the electric motor to move the moving member to the gas chamber side and to the side opposite to the gas chamber side. 6. The injection device according to any one of 1 to 5. The injection device according to any one of claims 1 to 6, wherein the electric motor is a servomotor. a die casting machine body including a sleeve and a plunger;
an injection device for moving the plunger of the die casting machine body,
The injection device is
an injection cylinder connected to the plunger and having an injection piston that advances due to increased pressure in the hydraulic chamber;
a piston accumulator disposed between the hydraulic chamber and the gas chamber and having an oil piston for pressurizing the hydraulic chamber;
a gas accumulator having a gas piston for pressurizing the gas chamber and connected in series with the piston accumulator;
a screw feed mechanism attached to the gas piston for moving the gas piston to the gas chamber side and a side opposite to the gas chamber side;
an electric motor that drives the screw feed mechanism ,
A die casting machine , wherein the screw feeding mechanism moves the gas piston toward the gas chamber while maintaining the volume of the gas chamber substantially constant .

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