JP4230066B2 - Brake circuit of injection molding machine and control method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a brake circuit for an injection cylinder or mold clamping cylinder of an injection molding machine and a control method therefor.
[0002]
[Prior art]
An example of an injection cylinder will be described with reference to FIG. 2 with respect to a conventional apparatus. A piston 2 to which a screw 1 is attached is slidably fitted in an injection cylinder 3, and an inner diameter portion of the injection cylinder 3 is formed. The forward oil chamber 4 and the reverse oil chamber 10 are divided. The forward oil chamber 4 of the injection cylinder 3 is provided with a pipe 6 for introducing the pressure oil from the hydraulic source 5 to the pipe 6 through the injection speed control throttle valve 9. A switching valve 8 for switching whether or not to act on the forward oil chamber 4 is provided.
[0003]
A pipe 11 is provided in the reverse side oil chamber 10 of the injection cylinder, and the return oil in the reverse side oil chamber 10 is returned to the oil tank 7 directly or via the brake speed adjusting throttle valve 12 in this pipe 11. A switching valve 13 is provided for switching between the two.
[0004]
The pressure oil from the hydraulic power source 5 acts on the forward oil chamber 4 of the injection cylinder 3 through the left chamber of the switching valve 8 at a flow rate predetermined by the throttle valve 9. The screw 1 moves forward (leftward in the figure) at a predetermined injection speed. On the other hand, the return oil from the backward oil chamber 10 returns directly from the pipe 11 to the oil tank 7 through the right chamber of the switching valve 13, so that the piston 2, that is, the screw 1 moves forward at high speed.
[0005]
To apply the brake against this high injection speed, the switching valve 13 is excited to switch from the right chamber to the left chamber, and the return oil from the reverse side chamber 10 is throttled from the piping 11 through the left chamber of the switching valve 13. The valve 12 is passed at a predetermined flow rate, and resistance is applied to the return oil so that the brake is applied.
[0006]
[Problems to be solved by the invention]
However, if the piston 2 does not move forward considerably, the pressure on the reverse-side oil chamber 10 side does not increase, and it takes time until the brake works, and the piston 2 advances as it is due to inertia, and the reverse-side oil chamber 10 There is a drawback that the optimum pressure cannot be maintained and the intended speed control cannot be performed.
[0007]
The object of the present invention is to eliminate the drawbacks of the above-mentioned disadvantages of the brakes and the inability to perform the intended speed control. The brakes of the injection molding machine are capable of quick braking and speed control with a predetermined pressure. To provide a circuit and a control method thereof.
[0008]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present invention divides the forward-side oil chamber and the backward-side oil chamber by a piston slidably fitted to the inner diameter portion, and advances and retracts the piston in the axial direction by pressure oil acting on both chambers. A cylinder to be operated and a forward oil chamber of the cylinder and a hydraulic source or an oil tank, and pressure oil from the hydraulic source is applied to the forward oil chamber via a throttle valve for adjusting the forward speed of the piston. A pipe provided with a first switching valve for switching whether or not, a cylinder back side oil chamber and a hydraulic source or an oil tank are connected, and pressure oil from the hydraulic source is supplied via a brake speed adjusting throttle valve. And a pressure sensor for detecting the pressure in the reverse oil chamber provided in the pipe provided with the second switching valve for switching whether or not to act on the reverse oil chamber and the pipe connected to the reverse oil chamber of the cylinder And the pressure sensor detects a predetermined pressure value. Time, and the brake circuit of an injection molding machine comprising a controller for the switching control of the second switching valve.
[0009]
Instead of the first switching valve and the forward speed adjusting throttle valve, a hydraulic servo valve capable of simultaneously controlling the pressure and flow rate, or the forward speed adjusting and brake speed adjusting throttle valve may be an electromagnetic proportional valve. Is preferred.
[0010]
As a result, when the brake is applied to the piston that is moving forward, the second switching valve adjusts the pressure oil from the hydraulic source to the brake speed adjusting throttle valve, and then the second switching valve in accordance with the timing of changing the opening of the throttle valve that adjusts the forward speed. The pressure sensor continues to monitor the pressure in the reverse side oil chamber while the pressure oil is acting on the reverse side oil chamber, and the pressure sensor moves backward. When a predetermined pressure value at which the side oil chamber reaches the optimum pressure is detected, the controller controls the brake circuit of the injection molding machine that switches the second switching valve so that the return oil from the reverse side oil chamber is returned directly to the oil tank. It is possible.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIG. 1, taking an injection cylinder as an example. In the description, the same members as those of the conventional example are denoted by the same reference numerals, the description thereof is omitted, and only the members newly added in the present invention are denoted by the new numbers and described.
[0012]
A pipe 15 is branched from between the hydraulic pressure source 5 and the injection speed control throttle valve 9 and connected to the upstream side of the brake speed adjustment throttle valve 12 so that when the brake is required during the forward movement of the piston 2, the injection speed control is performed up to now. The pressure oil from the hydraulic source 5 that has been applied to the forward side chamber 4 of the cylinder 3 via the throttle valve 9 and then the left chamber of the switching valve 8 is connected to the cylinder 3 via the pipe 15 and then the brake speed adjusting throttle valve 12. The pressure sensor 20 is attached to a pipe 11 connected to the reverse side oil chamber 10, and the pressure sensor 20 causes the pressure oil to act on the reverse side oil chamber 10. When the pressure sensor 20 detects a predetermined pressure value at which the reverse side oil chamber 10 is the optimum pressure, the return oil from the reverse side oil chamber 10 is directly oiled by a signal from the controller 21. Return to tank 7 It was to switch the cormorant switching valve 13.
[0013]
As a result, the pressure of the backward oil chamber 10 is increased with respect to the piston in advance, the brake is applied to the biston 2 moving at a high speed, and the backward oil chamber 10 is kept at an optimum pressure and is determined in advance. Speed control is possible with pressure.
[0014]
In the above-described embodiment, the case where the switching valve and the forward speed adjusting throttle valve are used for the forward movement of the piston has been described. However, the present invention is not limited to this. For example, a hydraulic servo valve may be used. Further, the throttle valve for adjusting the forward speed and adjusting the brake speed can be an electromagnetically controlled proportional valve.
[0015]
Although the above embodiment has been described with respect to the injection cylinder of the injection molding machine, the present invention is not limited to this, and the same applies to the brake circuit of the mold clamping cylinder.
[0016]
【The invention's effect】
The disadvantage that the brake circuit of the conventional injection molding machine listed at the beginning was poor and the reverse side oil chamber could not be maintained at the optimum pressure was removed, and the brake was applied quickly and the reverse side oil The chamber can be kept at an optimum pressure, and the speed can be controlled at a predetermined pressure.
[Brief description of the drawings]
FIG. 1 is a brake circuit diagram of an injection molding machine showing an embodiment of the present invention.
FIG. 2 is a diagram of a brake circuit of a conventional injection molding machine.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Screw 2 Piston 3 Injection cylinder 4 Forward side oil chamber 5 Hydraulic source 6, 11, 15 Piping 7 Oil tank 8 Switching valve 9 Forward speed adjusting throttle valve 10 Reverse side oil chamber 12 Brake speed adjusting throttle valve 13 Switching valve 20 Pressure sensor 21 controller

Claims (5)

A piston that is slidably fitted to the inner diameter part is divided into a forward oil chamber and a backward oil chamber, and a cylinder that advances and retracts the piston in the axial direction by pressure oil acting on both chambers, and a forward oil of the cylinder A first switching valve that connects between the chamber and a hydraulic source or an oil tank and switches whether or not the pressure oil from the hydraulic source is applied to the forward oil chamber via a piston forward speed adjusting throttle valve Between the piping provided with the cylinder, and the reverse side oil chamber of the cylinder and the hydraulic source or oil tank, and pressure oil from the hydraulic source is applied to the reverse side oil chamber via the brake speed adjusting throttle valve. A pipe provided with a second switching valve for switching whether or not, a pressure sensor for detecting the pressure in the backward oil chamber provided in the pipe connected to the backward oil chamber of the cylinder, and the pressure sensor having a predetermined pressure value Switch is detected and the second switching valve is switched. Brake circuit of an injection molding machine comprising and a controller. 2. The brake circuit for an injection molding machine according to claim 1, wherein the first switching valve and the throttle valve for adjusting the forward speed of the piston are replaced with hydraulic servo valves. 2. The brake circuit of an injection molding machine according to claim 1, wherein the first and second throttle valves are electromagnetically controlled proportional valves. 4. The brake circuit of an injection molding machine according to claim 1, wherein the cylinder is on one side for injection or mold clamping. A brake circuit for an injection molding machine according to claim 1, wherein when the brake is applied to the piston that is moving forward, the second switching valve is used to adjust the pressure from the hydraulic source by adjusting the opening of the forward speed adjusting throttle valve. The pressure oil is guided to the reverse oil chamber of the cylinder through the throttle valve for adjusting the brake speed and then the second switching valve, and the intermediate pressure sensor is operated while the pressure oil is acting on the reverse oil chamber. The second switching valve so that the controller returns the return oil from the reverse oil chamber directly to the oil tank when the pressure sensor detects a predetermined pressure that is the optimum pressure of the reverse oil chamber. The brake circuit control method of an injection molding machine characterized by switching.

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