JPS5938868B2 - Pressure increase device in injection device of die casting machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a pressure increase device in an injection device of a die-casting machine.

In general, the injection device of a die-casting machine is equipped with a pressure booster in order to obtain a cast product that is dense and has high dimensional accuracy.
At the end of the injection process, high pressure is generated in the injection cylinder to completely fill the mold cavity with molten metal. It is preferable that the timing of starting pressure increase, the time required for pressure increase, etc. can be arbitrarily adjusted.

Conventionally, position-sensing pressure boosters, pressure-sensing pressure boosters, etc. have been used as pressure boosters.In the former, the boost pressure can be easily adjusted, but the timing and timing of the start of pressure increase are It is difficult to adjust the pressure increase time, and in the latter case, although the timing of pressure increase start and the pressure increase time can be easily adjusted, the pressure increase time cannot be adjusted without changing the source pressure of the accumulation rake.

As described above, conventional pressure boosters have advantages and disadvantages in terms of collapse, making it difficult to select one.

The present invention has been made in view of this point, and can arbitrarily switch between the position detection method and the pressure detection method as necessary.
The present invention provides a pressure increase device that can be applied to molds of all shapes.

The pressure increase device of the present invention will be explained below in comparison with a conventional pressure increase device.

FIG. 1 is a circuit diagram showing an embodiment of a conventional position sensing type pressure increase device, in which the rod side chamber 26 of the pressure increase piston 25 is connected and communicated with the IJ valve 28 via the piping 27, and the pressure increase solenoid The valve 29 is connected to the IJ valve 28 via a pilot pipe 30 branched from the pipe 27, and the injection piston 32 of the injection cylinder 31
The movement in the injection stroke is detected by the limit switch LS, and the signal is sent to the pressure boosting solenoid valve 29 to switch the valve 29.
It should be activated.

With this configuration, if the set pressure of the IJ IJ valve 28 is adjusted appropriately, the pressure increase piston 25 is moved forward while receiving back pressure equal to the set pressure, so the pressure increase ratio can be changed arbitrarily. I can do it.

Also, since the pressure increase piston 25 is actuated at any position of the injection piston 32 by the limit switch LS, it has the advantage that pressure increase starts quickly. In some cases, the pressure increase piston 25 reaches the stroke end before reaching the stroke end, making it impossible to increase the pressure.Also, when the injection piston 32 stops and the pressure increases substantially, the pressure increase piston 25 always moves forward. Therefore, it is difficult to adjust the timing of the start of pressure increase.

Next, FIG. 2 is a circuit diagram showing an embodiment of a conventional pressure sensing type pressure increase device, in which the rod side chamber 36 of the pressure increase piston 35 is connected to the piping 3.
7 to the sequence valve 38, and the head side chamber 40 of the injection cylinder 39 is connected to the piping 41,
It is connected and communicated with the sequence valve 38 via a pilot pipe 42.

When using this configuration, after the injection piston 43 has completed advancing and the pressure in the head side chamber 40 has increased, the sequence valve 38 is opened and the pressure in the rod side chamber 40 of the pressure increasing piston 35 is increased.
6 is released, and the pressure boosting piston 35 moves forward to increase the injection pressure. Therefore, the set pressure of the sequence valve 38 can be adjusted to adjust the timing of the start of pressure increase. cannot be done without changing the source pressure of the accumulator 800.

FIG. 3 is a circuit diagram showing an embodiment of the pressure booster of the present invention. As is well known, solenoid valves 1 and 2 are excited to operate pilot checks 3 and 4, respectively, and a pump P sends a signal to an accumulator Acc. The pressure oil is transferred to piping 5.
through the head side chamber 7 of the injection cylinder 6,
The injection piston 8 is actuated to inject molten metal, and the hydraulic pressure in the rod side chamber 9 is released to the tank T via the piping 10.

Note that the injection speed is adjusted by a check valve 11 with a throttle provided in the pipe 5.

Reference numeral 12 denotes a pressure increase cylinder connected in series to the head side of the injection cylinder 6, which includes a pressure increase piston 13 therein, and connects and communicates the head side chamber 14 with the accumulation rake -Acc via a pipe 15 and a pipe 5.

16 is a throttle valve with a check valve provided in the pipe 15.

Reference numeral 17 denotes a sequence valve, which is connected to and communicates with the rod side chamber 19 of the pressure boosting piston 13 via a pipe 18, and is opened to the tank T via a pipe 20.

Reference numeral 21 denotes a pressure increase switching valve, which is connected to and communicates with the head side chamber 7 of the injection cylinder 6 via a pilot pipe 22, and connected and communicated with the rod side chamber 19 of the pressure increase piston 13 via a pilot pipe 23, and further communicates with the head side chamber 7 of the injection cylinder 6 via a pilot pipe 23. Piping 2
It is connected and communicated with the aforementioned sequence valve 1T via 4.

Further, a limit switch LS is arranged at an appropriate position during the injection process of the injection piston 8 to detect the movement of the injection piston 8, and the limit switch LS is connected to the increaser via the changeover switch SW as shown in FIG. Pressure switching valve 21
By switching this changeover switch SW to the solenoid valve side of the pressure increase changeover valve 21 in advance, when the limit switch LS is activated, the solenoid a or b of the changeover valve 21 It is configured to operate.

To explain the operation of the embodiment configured as above, when used as a pressure sensing type pressure increase device,
The changeover switch SW is previously switched to the solenoid a side of the pressure increase changeover valve 21, and then injection molding is performed.

During the injection process of the injection piston 8, when the movement of the piston is detected by the limit switch LS,
Solenoid a is turned on through the relay contact of relay R2 of changeover switch SW shown in FIG.
However, when switching to the A side, the hydraulic pressure in the head side chamber 7 of the injection cylinder 6 passes through the pipe 5 and the pilot pipe 22 to the pressure increase switching valve 21, and further passes through the pilot pipe 24 to act on the sequence valve 17. .

The injection piston 8 advances further to complete filling the mold with molten metal, and the oil pressure in the head side chamber 7 of the injection cylinder 6 rises to the pressure of the accumulation rake Acc. In this case, the operating pressure setting of the sequence valve 17 is changed to the accumulator If the pressure is set below Acc, the sequence valve 17 switches to release the oil pressure in the rod side chamber 19 of the pressure booster piston 13 to the tank T, and the pressure in the head side chamber 14 of the pressure booster cylinder 12 releases the pressure in the pressure booster piston. 13 moves forward,
The difference in area causes the oil pressure in the head side chamber 7 of the injection cylinder 6 to increase, completing the pressure increase operation.

In this case, if the difference between the pressure set value of the sequence valve 21 and the pressure of the accumulation rake -8cc is small, the time to start increasing the pressure will be delayed, and if this difference is large, the time to start increasing the pressure will be early.

(See FIG. 5N) Next, when the pressure increase device is to be used as a position sensing type pressure increase device, the changeover switch SW is switched to the solenoid B side of the pressure increase changeover valve 21 in advance, and then injection molding is performed.

During the injection process of the injection piston 8, when the movement of the piston is detected by the limit switch LS,
The solenoid b is turned on through the contact of the relay R1 of the changeover switch SW, the pressure increase changeover valve 21 is switched to the B side, and the hydraulic pressure in the rod side chamber 19 of the pressure increase piston 13 is changed to the piping 1.
8. Passes through the pilot pipe 23 to the pressure increase switching valve 21, and further passes through the pilot pipe 24 to act on the sequence valve 17 to operate it, and the pressure increase piston 13
The hydraulic pressure in the rod side chamber 19 is released to the tank T, and the pressure increasing piston 13 moves forward with the hydraulic pressure in the head side chamber 14 of the pressure increasing cylinder 12, increasing the hydraulic pressure in the head side chamber 7 of the injection cylinder 6, completing the pressure increasing operation. do.

In this case, the sequence valve 17 functions as a relief valve, so when setting the pressure of the sequence valve 17, back pressure is applied to the pressure increase piston 13,
The boost pressure can be adjusted by lowering the output of the pressure boost cylinder 12.

(See Figure 5N). Even in the case of the above collapse, the check valve 16 installed in the piping 15 that sends pressure oil from the accumulation rake-Acc to the pressure boosting cylinder 12.
The boost time can be adjusted by

As described above, the present invention includes an injection cylinder having an injection piston and a pressure increase cylinder having a pressure increase piston, and at the end of the injection process, high pressure is generated in the injection cylinder to melt the melt in the mold cavity. In an injection device for a die casting machine that is completely filled with metal, the rod side chamber of the pressure booster piston is opened to the tank via a sequence valve, and the head side chamber of the injection cylinder and the rod side chamber of the pressure booster piston are opened to the tank via a sequence valve. is connected and communicated with a pressure increase switching valve, and the sequence valve is actuated via the switching valve, and a limit switch or the like is installed to detect the movement of the injection piston at an appropriate position during the injection process. A device is provided, and the detection device is electrically connected to the pressure increase switching valve via a changeover switch, and the changeover switch is previously switched and connected to one of the solenoid sides of the pressure increase changeover valve. Since this relates to a pressure increase device in an injection device of a die-casting machine in which a pressure increase switching valve is switched in a predetermined direction by the operation of a detection device such as the limit switch, a sequence valve and a pressure increase switching valve are used. The movement of the injection bottle during the injection process is detected, the signal is selectively sent to one of the solenoids of the pressure increase switching valve, the switching valve is switched in a predetermined direction, the sequence valve is operated, and the pressure is increased. By operating the device, it can be used as a position sensing type pressure increasing device or a pressure sensing type pressure increasing device depending on the shape of the mold, and the range of use can be expanded.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention in comparison with a conventional embodiment, and FIG. 1 is a circuit diagram of a conventional position-sensing pressure booster, and FIG. 2 is a circuit diagram of a conventional pressure-sensing pressure booster. Figure 3 is a circuit diagram of the pressure booster of the present invention, Figure 4 is an electric circuit diagram showing the connection state of the limit switch and the solenoid of the pressure booster switching valve, and Figure 5 is a diagram showing the adjustment state of the pressure booster. It is an explanatory diagram. 6... Injection cylinder, 7... Head side chamber of the injection cylinder, 8... Injection piston,
12... Pressure boosting cylinder, 13... Pressure boosting piston, 19... Rod side chamber of pressure boosting piston, 17... Sequence valve, 21...・
・・Pressure increase switching valve, LS・・・Limit switch.

Claims (1)

[Claims] 1.Equipped with an injection cylinder having an injection piston and a pressure increase cylinder having a pressure increase piston, high pressure is generated in the injection cylinder at the end of the injection process to completely fill the mold cavity with molten metal. In the injection device of a die casting machine, the rod side chamber of the pressure booster piston is opened to the tank via the sequence valve, and the head side chamber of the injection cylinder and the rod side chamber of the pressure booster piston are connected and communicated with the pressure boost switching valve. The sequence valve is actuated via the switching valve, and a detection device such as a limit switch for detecting the movement of the injection piston is disposed at an appropriate position during the injection process of the injection piston, and the detection device is It is electrically connected to the pressure increase switching valve via a changeover switch, and the changeover switch is connected in advance to one of the solenoid sides of the pressure increase changeover valve, so that the detection device such as the limit switch is actuated. 1. A pressure increase device in an injection device of a die-casting machine, characterized in that the pressure increase switching valve is configured to switch in a predetermined direction.