JPH0794061B2 - Injection molding machine drive - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a drive device for an injection molding apparatus such as a die casting machine or an injection molding machine, and more specifically, to a low pressure at the time of filling and a pressure force after filling (for example, The present invention relates to a drive device of an injection molding device capable of increasing the pressure of molten metal.

[Prior Art] In a drive device of an injection molding device such as a die casting machine or an injection molding machine, a hydraulic pressure from a hydraulic pump is applied to a hydraulic cylinder, and the plunger in the hydraulic cylinder is moved forward to interlock with the plunger. Configured to advance the injection plunger.

In the drive unit of this injection molding apparatus, after filling the mold with a material (for example, molten metal or soft synthetic resin),
Further, this material is pressed (in the case of metal, it is heated) to densify the material in the mold. In order to perform such densification, a mechanism for increasing the forward pressure of the plunger of the hydraulic cylinder at the end of filling is provided.

As a plunger forward pressure increasing mechanism, a gas pressure type low pressure accumulator and a high pressure accumulator may be provided between a hydraulic pump and a hydraulic cylinder.

At the beginning of filling the mold with material, the plunger of the hydraulic cylinder is advanced at a relatively low speed, with hydraulic fluid being stored under pressure in the accumulator. From the middle stage to the latter stage of the filling process, the piston of the hydraulic cylinder is advanced at high speed. At this time, the hydraulic oil stored in the low pressure accumulator is supplied to the hydraulic cylinder, and the piston of the hydraulic cylinder is advanced at high speed. After the filling is completed, a high pressure hydraulic pressure is applied to the hydraulic cylinder from the high pressure accumulator to pressurize the material at a high pressure.

The reason why the filling speed of the material is set to be slow in the initial stage and to be high in the middle stage to the latter stage in this way is as follows.

That is, when the filling pressure is high in the initial stage of the material filling process, the material is injected into the mold having a large empty volume so as to be violently blown, so that air bubbles are easily entrained in the material. To avoid this, the initial filling pressure should be as low as possible.

From the middle stage to the latter stage of the filling process, since the empty volume in the mold is small, there is almost no entrainment of bubbles in the material as described above. Therefore, the filling speed is increased and the molding time is shortened.

[Problems to be Solved by the Invention] As described above, when two accumulators are used and the pressure increase during high-speed filling and the pressure increase for densification after completion of filling are performed by different accumulators, There are many installed units, which increases equipment costs. There is also a problem that it is not easy to match the timing of stopping the hydraulic pressure supply from the low pressure accumulator with the timing of starting the hydraulic pressure supply from the high pressure accumulator.

As another known pressure increasing mechanism, there is a mechanism in which a large-diameter piston is connected to the rear portion of the piston of the hydraulic cylinder and a hydraulic pressure is applied to the large-diameter piston when increasing the pressure. This mechanism has a problem that the length of the hydraulic cylinder is unnecessarily large.

[Means for Solving the Problems] A drive device of an injection molding apparatus of the present invention includes a hydraulic cylinder that pushes a material injection plunger of the injection molding apparatus to move it forward, a hydraulic pump that supplies hydraulic pressure to the hydraulic cylinder, With a drive device of an injection molding device including an accumulator connected to a hydraulic path from a hydraulic pump to a hydraulic cylinder, and a flow rate control valve provided on a hydraulic path between a part to which the accumulator is connected and a hydraulic cylinder. Therefore, the accumulator includes a piston biased by a gas pressure from a high-pressure gas source, and a plurality of accumulator chambers for accumulating and storing hydraulic oil by the piston, and a hydraulic pressure from the accumulator to a hydraulic cylinder. The passage is provided with valve means for increasing or decreasing the number of pressure accumulating chambers that supply hydraulic pressure to the hydraulic cylinder. .

[Operation] In the drive device of the injection molding apparatus of the present invention, the opening of the flow rate control valve is narrowed to reduce the amount of oil supplied to the injection hydraulic cylinder at the beginning of the process of filling the material into the mold. And lower the hydraulic pressure to fill the material at low speed and low pressure. At this time, the hydraulic oil is stored in all the pressure accumulating chambers of the accumulator.

In the latter stage of the material filling process, the opening degree of the flow rate control valve is increased, and the hydraulic oil is supplied from all the accumulator accumulators toward the hydraulic cylinder. As a result, filling is performed at high speed and with higher pressure than before.

After the material is filled in the mold, hydraulic oil is supplied to the hydraulic cylinder from only a part of the accumulator pressure chambers. With this configuration, the supply pressure from the accumulator becomes higher than that in the case where the hydraulic oil in all the pressure accumulating chambers is applied to the hydraulic cylinder, so that the forward force of the hydraulic cylinder can be increased.

That is, when the pressure of all the accumulators is applied to the hydraulic cylinder, this pressure corresponds to the gas pressure applied to the piston of the accumulator. On the other hand, when only some of the pressure accumulating chambers apply hydraulic pressure to the hydraulic cylinders, the metal mold of the gas pressure applied to the piston is applied to the some of the accumulating chambers, so that the hydraulic pressure in the accumulating chambers increases significantly. As a result, the forward pressure of the piston of the hydraulic cylinder can be significantly increased.

Embodiments Embodiments will be described below with reference to the drawings.

1 to 4 are hydraulic circuit diagrams of a drive unit of an injection molding apparatus according to an embodiment of the present invention. This drive device includes a hydraulic cylinder 10 for pressing and advancing a material injection plunger of an injection molding device, and hydraulic pumps 12, 14 as hydraulic pressure sources for supplying operating hydraulic pressure to the hydraulic cylinder 10.
It is mainly composed of an accumulator 20 which is installed in the hydraulic cylinder 10 so as to be able to transmit accumulated pressure, and a high pressure gas cylinder 22 which adds high pressure gas to the accumulator 20.

The hydraulic cylinder 10 includes a cylinder barrel 24, a plunger 26 that is installed in the cylinder barrel 24 such that the cylinder barrel 24 can move forward and backward, and the tip side of the plunger 26 projects from the tip side of the cylinder barrel 24.
A stopper 28 arranged on the rear side of the plunger 26 and a hollow tube 30 fixedly installed through the stopper 28 and the plunger 26 are provided. The tip side of the stopper 28 is a small diameter part, and the hydraulic pressure introducing chamber 32
Is provided. A rear end of the plunger 26 slides on the inner peripheral surface of the cylinder barrel 24, and a front side of the plunger 26 has a smaller diameter. An outer peripheral chamber 34 is provided between the outer periphery of the small diameter portion and the inner peripheral surface of the cylinder barrel 24. The plunger 26 has a hollow structure and includes an internal chamber 36. The inner chamber 36 and the outer chamber 34 are communicated with each other through an opening 38.

The stopper 28 also has a hollow structure and includes a relay chamber 40. The internal chamber 36 and the relay chamber 40 are communicated with each other through openings 42 and 44 formed in the peripheral surface of the hollow tube 30.

This hydraulic cylinder has a port 46 for introducing and discharging hydraulic pressure,
It has 48, 50 and 52.

The accumulator 20 includes a cylinder 54 and a cylinder 54.
And a piston 56 slidably inserted therein.
The piston 56 has a large diameter on the base end side and a piston small diameter portion 56a on the tip end side. In the cylinder 54, a first pressure accumulating chamber 58 composed of a small diameter portion on which the piston small diameter portion 56a slides, and a second pressure accumulation chamber formed between the large diameter portion of the cylinder 54 and the peripheral surface of the piston small diameter portion 56a. 60 and are provided. Reference numeral 62 denotes a passage for communicating the inside of the second pressure accumulating chamber 60 with the outside.

The hydraulic pumps 12 and 14 are connected to a switching valve 66 via a pipe 64. The switching valve 66 is connected to the hydraulic tank T, and is also connected to the passage 62 of the accumulator 20 via the pipe 70, the check valve 72, and the pipes 74 and 76. The switching valve 66 is
Piping 78, Sequence valve 80, Pilot check valve 82, Piping 8
It communicates with the port 46 of the hydraulic cylinder 10 via 4, 86. The check valve 88 should bypass the sequence valve 80.
Is provided.

The hydraulic pump 16 includes a pipe 88, a switching valve 90, a pipe 92, a check valve 9
4, connected to the cartridge valve 100 via pipes 96, 98. The cartridge valve 100 is connected to the first pressure accumulating chamber 58 of the accumulator 20 via a pipe 102. Another pipe 104 branches from the connecting portion between the pipe 96 and the pipe 98,
The pipe 104 is connected to a variable throttle valve 106. Reference numeral 108 denotes a motor for adjusting the circuit of the variable throttle valve 106. The variable throttle valve 106 is a port of the hydraulic cylinder 10 via a pipe 110.
It is connected to 48.

Another pipe 112 branches from the middle of the pipe 110, and is connected to a switching valve 118 via a check valve 114 and a pipe 116.
The switching valve 118 is connected to the back pressure introducing side of the cartridge valve 100 via a pipe 120. In addition, the switching valve 118 is pipe 1
It is connected to the tank T via 22 and communicates with the first pressure accumulating chamber 58 via another pipe 124 and the pipe 102.

The middle of the pipe 102 is connected to the connecting portion between the pipe 74 and the pipe 76 via a pipe 128 having a check valve 126.

Piping 1 for connecting the variable throttle valve 106 and the hydraulic cylinder 10
Another pipe 130 branches off from the middle of 10, and is connected to a switching valve 136 via a variable throttle valve 132 and a pipe 134.
This switching valve 136 is connected to the tank T, and the check valve 1
It communicates with the pilot port of the pilot check valve 144 via the 38, the sequence valve 140, and the piping 142. The pilot check valve 144 is connected to the pipe 74.

The pipe 142 is connected to the switching valve 148 via another pipe 146. This switching valve 148 includes the pipe 134 and the sequence valve 150.
And a check valve 152. A pipe 154 branches off from the pipe between the valves 150 and 152.
Is connected to the pilot port of the pilot check valve 82.

The switching valve 136 is a check valve 156 and a pipe 158.
It is connected to the pipe 142 via.

The port 52 of the hydraulic cylinder 10 is connected to the outer peripheral chamber 34 via a pipe 160, a cartridge valve 162, a pipe 164, a cartridge valve 166 and a pipe 86.

The pipe 78 is connected to the back pressure side of the cartridge valve 162 via the pipe 168, the check valve 170, the pipe 172, the switching valve 174 and the pipe 176 in order to supply the control hydraulic pressure to the cartridge valve 162. An intermediate portion of the pipe 172 is connected to the pipe 164 via a sequence valve 178.

A pipe 180 branches from the pipe 164, and the hydraulic pressure on the back pressure side of the cartridge valve 166 can be controlled via the switching valve 182 and the pipe 184. An intermediate part of the pipe 164 is connected to the port 50 via the pipe 186.

The pipe 84 can communicate with the tank T via a switching valve 188.

In the drive unit of the injection molding apparatus configured as described above, in order to fill the material (in this embodiment, molten metal) into the mold, the material is first filled at a low speed. In this case, the first
As shown, the switching valves 66, 90, 118 and 188 are turned on.
Further, the circuit of the variable throttle valve 106 is narrowed down. In this state, the hydraulic pumps 12, 14, 16 are operated. Hydraulic pump
Hydraulic fluid from 16 is pipe 88, switching valve 90, pipe 92, check valve 9
4, flow through the pipe 96. Some of this hydraulic oil is pipe 1
It is supplied to the hydraulic cylinder 10 through 04, the variable throttle valve 106, and the pipe 110, and flows into the introduction chamber 32. Since the area of the rear surface side of the plunger 26 is larger than the area of the front surface side thereof, the hydraulic pressure supplied into the introduction chamber 32 pushes the plunger 26, thereby moving the plunger 26 forward at a low speed. That is, since the opening of the variable throttle valve 106 is narrowed, the speed of the hydraulic pressure flowing into the introduction chamber 32 is low, and the forward speed of the plunger 26 is low. As the plunger 26 advances, the hydraulic oil in the outer peripheral chamber 34 flows into the introduction chamber 32 through the pipes 86, 164, 186.
The hydraulic oil in the outer peripheral chamber 34 is stored in the opening 38, the inner chamber 36, and the opening 4
2. The hollow pipe 40, the opening 44, the relay chamber 40, and the pipes 160, 164, and 186 also flow into the introduction chamber 32.

In this way, while the hydraulic cylinder 10 is moving forward at low speed,
A part of the hydraulic oil flowing from the hydraulic pump 16 through the pipe 96 passes through the pipe 98, the cartridge valve 100, and the pipe 102, and the first pressure accumulating chamber.
It flows into 58 and pushes up the piston 56 of the accumulator 20.

The hydraulic oil sent from the hydraulic pumps 12 and 14 is the switching valve 6
6, it reaches the accumulator 20 through the pipe 70, the check valve 72, the pipes 74 and 76, flows into the second pressure accumulating chamber 60 through the passage 62, and pushes up the piston 56.

The switching valves 118, 174, 182 are selected so that the back pressure of the cartridge valves 100, 162, 166 can be released.

After filling the material in the mold at a low speed as shown in FIG. 1,
Fill the material into the mold at high speed. In order to perform this high-speed filling, the flow path is selected in the same manner as in the low-speed filling except that the opening degree of the variable throttle valve 106 is increased. Then, the second
As shown in the figure, the total amount of hydraulic oil from the pipe 96 is the variable throttle valve.
The oil is supplied to the hydraulic cylinder 10 through 106. Further, the hydraulic oil stored in the pressure accumulating chambers 58 and 60 of the accumulator 20 is also urged by the gas pressure from the high-pressure gas cylinder 22 to urge the piston 56, so that the variable throttle valve 106, respectively, in the opposite manner to the case of FIG. And is supplied to the hydraulic cylinder 10. Further, the hydraulic oil from the hydraulic pumps 12, 14 sent via the pipes 64, 70, 74 also flows toward the pipe 128 side, passes through the variable throttle valve 106, and passes through the hydraulic cylinder 1
Supplied within 0.

In this way, the hydraulic oil of all the hydraulic pumps 12, 14, 16 is supplied to the hydraulic cylinder 10, and the total amount of hydraulic oil from the accumulator 20 is also supplied to the hydraulic cylinder 10. 26 moves forward at high speed, and the mold is filled with the material at high speed.

After high-speed filling is performed to fill a sufficient amount of material in the mold, feeder pressure is applied to the material in the mold. When carrying out this feeder, as shown in FIG. 3, the switching valve 136 is turned on. In this case, the hydraulic pumps 12 and 14 are stopped,
Only the hydraulic pump 16 is operated. Further, the switching valve 66 is turned off. Although the switching valve 174 is turned on, the switching valve 1
Even if 74 is turned on, the operation of the cartridge valve 162 is the same as above.

In the flow path selection of FIG. 3, the hydraulic oil from the pump 16 is transmitted to the hydraulic cylinder 10 through the pipes 88, 92, 96, 104 and 110, and the hydraulic pressure of the first accumulator 58 is set to the pipes 102 and 98. , 1
It is transmitted to the hydraulic cylinder 10 through 04 and 110.

In this case, since the switching valve 136 is turned on, the hydraulic pressure of the pipe 110 is transmitted to the pilot check valve 144 via the pipes 130 and 134, the switching valve 136, the valves 138 and 140, and the pipe 142. For this reason, pipe 7
4 is communicated with the tank T. Therefore, the accumulator 20
The pressure in the second pressure accumulating chamber 60, which is about to be generated as the piston 56 moves forward, is entirely in the tank T via the pipes 76 and 74.
Be dropped by.

As described above, in the accumulator 20, the total pressure of the pressure applied from the high pressure gas cylinder 22 to the piston 56 is applied to the first pressure accumulating chamber 58, and an extremely high pressure is generated in the first pressure accumulating chamber 58. To do. This first accumulator 58
Since the high pressure is transmitted to the hydraulic cylinder 10, the plunger 26 is subjected to an extremely high forward pressure, and a high feeder pressure is applied to the material in the mold.

After the injection molding of the material is completed, the switching valves 90, 118, 136 are turned off to retract the plunger 26. Further, the switching valve 66 is turned on to connect the pipes 64 and 78. Switching valve 174
Is turned on as in FIG. In this state, only the hydraulic pump 12 is operated. Then, the hydraulic pump 12
Hydraulic fluid from the pipes 64, 78, valves 80, 88, 82, pipes 84, 86
To the outer peripheral chamber 34 and the inner chamber 36 of the hydraulic cylinder 10. As a result, the hydraulic oil in the introduction chamber 32 is
12. Return to the tank T through the check valve 114, the pipe 116, the switching valve 118, and the pipe 112.

The hydraulic pressure in the pipe 78 applies back pressure to the cartridge valve 166 via the pipes 168 and 186, the switching valve 182 and the pipe 184, and further backs the cartridge valve 162 via the pipe 172, the switching valve 174 and the pipe 176. Give pressure. As a result, the cartridge valves 166 and 162 are closed.

As is clear from the above description, in this embodiment, the accumulator 20 is used to generate a high feeder pressure in the hydraulic cylinder 10. The switching from the high-speed filling to the pressing hydraulic pressure can be performed simply by turning on the switching valve 136, and switching can be performed extremely easily and in a short time.

Further, by adjusting the opening of the variable throttle valve 106, switching from low speed filling to high speed filling can be performed very easily.

[Effects] As described above, according to the drive device of the injection molding apparatus of the present invention, it is possible to perform high-speed filling and pressurization of material after completion of filling such as feeder with one accumulator. Moreover, the switching between the high speed filling and the material pressurization can be performed by a simple flow path switching mechanism, which is extremely simple. In the drive device of the present invention, it is unnecessary to unnecessarily lengthen the length of the hydraulic cylinder, and since the number of accumulators installed is small, the equipment cost is low and the installation space of the device is small.

[Brief description of drawings]

1, FIG. 2, FIG. 3 and FIG. 4 are hydraulic circuit diagrams of the drive device according to the embodiment of the present invention. 10 …… hydraulic cylinder, 12, 14, 16 …… hydraulic pump, 20 …… accumulator, 58 …… first accumulator, 60 …… second accumulator, 66, 90, 118, 136, 148, 174, 176 , 188 …… Switching valve.

Claims (1)

[Claims] 1. A hydraulic cylinder for pushing a material injection plunger of an injection molding apparatus to move it forward, a hydraulic pump for supplying hydraulic pressure to the hydraulic cylinder, and an accumulator connected to a hydraulic path from the hydraulic pump to the hydraulic cylinder. A drive device of an injection molding apparatus comprising a flow rate control valve provided in a hydraulic path between a portion to which the accumulator is connected and a hydraulic cylinder, wherein the accumulator is operated by a gas pressure from a high pressure gas source. It is equipped with a biased piston and a plurality of pressure accumulating chambers for accumulating and storing hydraulic oil by the pistons. In the hydraulic path from the accumulator to the hydraulic cylinder, the number of accumulating chambers that supply hydraulic pressure to the hydraulic cylinder. A drive device for an injection molding apparatus, characterized in that valve means for increasing and decreasing the pressure is provided.