JP3202361B2 - Brake device for injection molding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake device for reducing a mold clamping speed in an injection molding machine.

[0002]

2. Description of the Related Art In a conventional injection molding machine, the operation of a mold clamping cylinder is accelerated to increase the mold closing speed in order to increase the cycle. However, if the dies collide with each other at a high speed, the dies may be damaged. In order to switch to the above, a brake device that reduces the discharge amount of the pressure oil from the hydraulic supply source (the supply amount of the pressure oil into the mold clamping cylinder) and forcibly reduces the speed is used. As an example of such a brake device, Japanese Patent Publication No.
Japanese Patent Application Publication No. -3895 has proposed. In this brake device, when pressure oil is supplied to one of the two chambers defined by the pistons of the mold clamping cylinder during mold clamping, the pressure oil that has entered from the other chamber is discharged, and this pressure oil is discharged. The mold clamping speed is reduced by utilizing the fact that the operation speed of the piston is reduced by reducing the discharge amount.

A hydraulic circuit for mold clamping using one example of this brake device will be described with reference to FIG. 3. A mold clamping cylinder 1 is divided into a chamber A by a piston 1a and a chamber B in which a piston rod 1b is inserted. Has been established. The variable displacement pump 2 has a suction side connected to the tank T and a discharge side connected to the discharge pipe 3. The discharge line 3 is branched in the middle, one is connected to the room A via the line 4, the other is connected to the room B via the line 5, and the discharge line 3 is connected to the side line 6. Is provided with a relief valve 7 to prevent the discharge pressure of the variable displacement pump 2 from exceeding a certain level. Each of the pipelines 4 and 5 is provided with a cartridge valve 8 and 9 for supplying pressure oil from the variable displacement pump 2 by selecting either the chamber A or the chamber B of the mold clamping cylinder 1. It is. The cartridge valve 8 and the chamber A are branched and a pipe 10 is provided. The pipe 10 is provided with a cartridge valve 11. When the cartridge valve 11 is opened, the pressure oil passing through the pipe 4 is supplied to the tank T. It can be returned to. The pipe 5 is also branched and provided with a discharge pipe 12, and the discharge pipe 12 is provided with cartridge valves 13 and 14 as brake devices in parallel. The pressure oil is returned to the tank T by opening the cartridge valves 13 and 14.

On the other hand, a pilot line 15 for controlling the opening and closing of each cartridge valve is connected to the discharge line 3 of the variable displacement pump 2, and the pilot line 15 is connected to a check valve 16. After that, one is connected to an electromagnetic pilot switching valve 17 at a four-port three position, and the other is connected to an electromagnetic pilot switching valve 18 at a four-port two position. In addition, an electromagnetic pilot switching valve 1 with 4 ports and 3 positions
7, a pilot line 19 for opening and closing the cartridge valve 8 and the cartridge valve 14 and a cartridge valve 9 are provided.
And a pilot line 20 for opening and closing the cartridge valve 11. Further, a pilot line 21 in which a throttle 24 for opening and closing the cartridge valve 13 is provided in the electromagnetic pilot switching valve 18 at the 4-port 2-position.
Is connected.

When the electromagnetic pilot switching valve 17 at the 4-port 3-position is switched to the side a from the state shown in FIG. 3, the cartridge valves 9 and 11 are closed by applying pilot pressure, and the pilot pipes of the cartridge valves 8 and 14 are closed. Road 19 is tank T
Connected to. Accordingly, the hydraulic pressure from the variable displacement pump 2 is supplied to the chamber A of the mold clamping cylinder 1 through the cartridge valve 8, and operates the piston 1a in the mold clamping direction. At this time, room B
The pressure oil on the side is returned to the tank T through the discharge line 12 and the cartridge valves 13 and 14. Subsequently, the limit switch 22 detects that the moving mold (not shown) has approached the fixed mold.
To reduce the discharge amount of the main hydraulic pump 2 and
The electromagnetic pilot switching valve 18 at the port 2 position is switched from C to d.

[0006] 4 port 2 position electromagnetic pilot switching valve 1
8, the cartridge valve 13 is closed by the application of pilot pressure, and the pressure oil discharged from the chamber B of the mold clamping cylinder 1 is returned to the tank T from the passage of the cartridge valve 14 alone. The discharge amount of the pressure oil from the chamber B is reduced, and the piston 1a has a braking action. When the mold clamping speed is switched from the high speed to the low speed in this manner, in the above hydraulic circuit, the brake device is constituted by the two cartridge valves 13 and 14 and the electromagnetic pilot switching valve 18 at the 4-port 2-position. . The mold is opened by switching the electromagnetic pilot switching valve 17 at the 4 port 3 position to b, whereby the cartridge valves 8 and 14 are closed, the cartridge valves 9 and 11 are opened and the chamber B of the mold clamping cylinder 1 is opened. The pressure oil is supplied, and the pressure oil in the chamber A is discharged to the tank T through the pipe 10.

[0007]

The brake device of the injection molding machine constructed as described above is operated by closing the cartridge valve 13 by operating the electromagnetic pilot switching valve 18, and the operating oil pressure of the pilot switching valve 18 is variable. This is the discharge pressure of the displacement pump 2. Therefore, when the mold clamping operation is performed at a high speed, a surge pressure is generated when the cartridge valve 13 attempts to close due to a large flow rate of the pressure oil discharged from the chamber B of the mold clamping cylinder 1 and the cartridge valve 13 is closed. In some cases, he lost and did not work well as a brake. Also, by increasing the hole diameter of the orifice 24 between the pilot switching valve 18 and the cartridge valve 13, it is effective to increase the amount of pilot oil flowing into the cartridge valve 13. However, when the weight of the mold is large, Causes an excessive impact. Further, removing or changing the orifice 24 in order to change the hole diameter of the orifice requires stopping the operation of the molding machine and disassembling the solenoid valve, which is troublesome and hinders improvement in productivity. SUMMARY OF THE INVENTION An object of the present invention is to provide a brake device for an injection molding machine capable of optimizing a brake switching timing without changing an orifice diameter, and to solve the above-mentioned conventional problems.

[0008]

According to the present invention, a cartridge valve connected to a cylinder chamber defined with a piston of a mold closing cylinder is opened and closed by a pilot hydraulic pressure via a pilot switching valve to start braking. In a brake device of an injection molding machine that operates a cartridge valve connected to one of the cylinder chambers by a signal of a detector, a hydraulic pump that supplies oil pressure to the cylinder chamber is provided.
Pie for supplying hydraulic pressure to operate the cartridge valve
Lot hydraulic pump and hydraulic pressure of the pilot hydraulic pump
Pressure regulating valve for regulating the pressure and supplying it to the cartridge valve
And detecting the signal of the brake start detector and detecting the pressure
A control device for controlling the set pressure of the regulating valve , which is used as means for solving the problem.

[0009]

[Action] When the brake start of the mold clamping cylinder in the injection molding machine is detected by the detector, the pressure adjusted by the pressure control valve the hydraulic pressure source from the main hydraulic pump is installed separately from the pilot hydraulic pump, cartridge valve Is operated, and unlike the pressure of the main hydraulic pump, the brake operation can be smoothly performed by the hydraulic pressure against the surge pressure generated at the time of braking.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. In the embodiment of the present invention, parts having the same configuration as those of the related art will be described with the same reference numerals, and description of the same circuit as the hydraulic circuit of FIG. Only the part will be described. Now, in the conventional hydraulic circuit shown in FIG. 3, the pilot line 15 is connected to the discharge side line 3 of the variable displacement pump 2 (main hydraulic pump), whereas in the present invention, it is clearly shown in FIG. As described above, it is connected to the discharge side pipe 31 of the pilot hydraulic pump 30 installed separately from the variable displacement pump 2, and the discharge side pipe 31 has a pressure regulating valve 33 (a proportional electromagnetic relief valve) for adjusting pressure. ) Is attached, and when the pressure exceeds a set pressure, the pressure is discharged to the tank T to maintain the pressure. At the start of braking, a control device 32 is provided which detects the signal of the limit switch 22 to reduce the discharge amount of the main hydraulic pump 2 and appropriately controls the set pressure of the pressure adjusting valve 33.

Next, the operation of the embodiment constructed as described above will be described. First, when the electromagnetic pilot switching valve 17 at the 4 port 3 position is switched to the a side from the state of FIG. 1, the mold opening cartridge valve 9 and the discharge A cartridge valve 11 are closed by applying pilot pressure, and the mold clamping cartridge valve 8 is closed. The pilot line 19 of the discharge B cartridge valve 14 is the tank T
Connected to. Accordingly, the hydraulic pressure from the main hydraulic pump 2 passes through the mold clamping cartridge valve 8 and is supplied to the chamber A of the mold clamping cylinder 1 to operate the piston 1a in the mold clamping direction. At this time, the pressure oil on the chamber B side is discharged from the discharge line 12, the cartridge valves 13, 1
4 and returned to the tank T. Subsequently, when a moving mold (not shown) approaches the fixed mold, the approach is detected by a limit switch 22 as a brake start detector for starting a braking operation. In addition to reducing the discharge rate, the pilot pilot pump 3
The pressure is switched from c to d by the oil pressure adjusted by the pressure adjustment valve 33 installed in the discharge line of No. 0. This 4 port 2
The pilot pressure is applied to the cartridge valve 13 by switching the electromagnetic pilot switching valve 18 in the position, the cartridge valve 13 is closed, and the pressure oil discharged from the chamber B of the mold clamping cylinder 1 is discharged from the passage only by the cartridge valve 14 to the tank. As a result, the amount of pressurized oil discharged from the chamber B of the mold clamping cylinder 1 is reduced, and a braking action is generated on the piston 1a.

Further, as the mold clamping speed increases, the flow rate of the pressure oil discharged from the chamber B of the mold clamping cylinder 1 increases, and when the cartridge valve 13 attempts to close, the surge pressure generated in the pipe 12 increases. Therefore, it is necessary to make the pilot hydraulic pressure not to lose this surge pressure. However, in the present invention, the pilot hydraulic pressure can be controlled by the pilot hydraulic pump 30 and the pressure adjusting valve 33 as described above. Can be set to any pressure different from the pressure.

The graph shown in FIG. 2 shows the mold clamping speed in a high speed range and the set value of the pilot oil pressure suitable for this. By setting the pilot pressure to a pressure as shown in FIG. 2 immediately after the start of the brake or after the start of the mold clamping, it is possible to improve the responsiveness of the brake operation according to the mold clamping speed in a high-speed region. Further, since the pressure setting valve 33 can easily change the pressure setting by remote control by the control device 32, the troublesome adjustment of changing the hole diameter of the orifice 24 becomes unnecessary. The mold is opened by switching the electromagnetic pilot switching valve 17 at the 4 port 3 position to b to close the cartridge valves 8 and 14, open the cartridge valves 9 and 11, and apply pressure to the chamber B of the mold clamping cylinder 1. The oil is supplied, and the pressure oil in the chamber A is discharged to the tank T through the pipe 10. At this time, a cartridge valve with a throttle may be provided in parallel with the cartridge valve 11 so that the brake can be applied even when the mold is opened. If the pilot oil pressure of the cartridge valve 11 is adjusted according to the mold opening speed in the same manner as described above, the responsiveness of the brake can be improved even when the mold is opened.

[0014]

As described above in detail, according to the brake device of the injection molding machine of the present invention, the operation of the brake cartridge valve can be set to a pilot oil pressure higher than the surge pressure generated during braking, and the response of the brake operation is thus improved. The responsiveness of the brake can be improved, and the responsiveness of the brake can be easily adjusted with the pilot oil amount . Moreover, since the pilot oil pressure of the brake cartridge valve can be controlled during operation by remote control,
There is no need to stop the operation and replace the orifice as in the case of adjusting the pilot oil pressure by changing the orifice diameter.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of an injection molding machine showing an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a mold clamping speed and a pilot oil pressure set value in FIG. 1;

FIG. 3 is a hydraulic circuit diagram of a conventional injection molding machine.

[Explanation of symbols]

 Reference Signs List 1 mold clamping cylinder 2 main hydraulic pump 8, 9 cartridge valve 11, 13, 14 cartridge valve 17 electromagnetic pilot switching valve 18 electromagnetic pilot switching valve 22 limit switch as brake start detector 30 pilot hydraulic pump 32 control device 33 pressure regulating valve (Proportional solenoid relief valve) T tank

Claims (1)

(57) [Claims] A cartridge valve connected to a cylinder chamber defined with a piston of a mold clamping cylinder opened and closed by a pilot hydraulic pressure via a pilot switching valve, and a signal from a brake start detector is used to open or close the cartridge valve. In a brake device of an injection molding machine for operating a cartridge valve connected to a cylinder chamber, a hydraulic pump for supplying oil pressure to the cylinder chamber and a pump for supplying oil pressure for operating the cartridge valve are provided.
Adjust the hydraulic pressure of the pilot hydraulic pump and the pilot hydraulic pump to adjust the cart
A pressure regulating valve to be supplied to the ridge valve, and the pressure regulation by detecting a signal of the brake start detector.
A brake device for an injection molding machine , comprising: a control device for controlling a set pressure of a valve .