JPS5933130A - Oil-pressure circuit for injection molding machine - Google Patents

Abstract

PURPOSE:To save the consumption of excessive pressures by a method in which plural pressure storage devices having different pressure-storabilities are provided to an oil-pressure circuit, and the oil pressures from the pressure storage devices of adequate pressures are used for drive operations, e.g., injection, weighing, the opening and closing of molds, etc. CONSTITUTION:Three pressure storage devices 19-21 for high-, medium-, and low-pressures are provided to the inside of the oil-pressure circuit of an injection molding machine. The stored pressures of the devices 20, 19 and 21 for medium, high and low pressures are applied to the circuits of a mold-clamping cylinder 18, an injection cylinder 14 and an oil-pressure motor (actuator) B through the switching positions (a) and (b) and the intermediate position of solenoid switch valves 22-24.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic circuit for an injection repair machine, etc., which uses a pressure accumulator to control operations such as injection, metering, and mold opening/closing.

Conventionally, pressure accumulators have often been used in the hydraulic circuits of injection molding machines, etc. For example, a pressure accumulator is connected to the injection cylinder with a reservoir at the tip of a screw to ensure a cushioning effect during injection, or A piston integrated with a rotatable screw shaft, as seen in Publication No. 37-6729, and a cylinder fitted thereto are communicated with each other by a pressure accumulator that coexists with gas and liquid, and pressure fluctuations in the pressure system are suppressed. The range of reciprocating motion of the screw shaft is always maintained by supplying or discharging pressure fluid from the outside into the pressure system by electrically, hydraulically, or mechanically compensating according to changes in the axial movement distance of the screw shaft. A method of limiting the temperature within a certain adjustable range is known.

However, each method uses one pressure accumulator and is used only in one series, such as the control circuit for the injection device or the control circuit for the mold clamping device. Therefore, it would be more economical to use the pressure accumulator not only in one system but also in multiple systems, such as the control circuit of the injection device. However, when used in multiple series, for example, when three series such as injection, metering, and mold opening/closing operating at different pressures are operated with one pressure accumulator, the pressure accumulator is used for three series such as injection, metering, mold opening/closing, etc. Pressure accumulation must be carried out in accordance with the series that requires the highest pressure among the series operations. Therefore, even when operating a series that does not require high pressure, the maximum pressure is not applied, and extra pressure is consumed, resulting in wasted energy.

The present invention eliminates the above-mentioned drawbacks and provides a hydraulic circuit for an injection molding machine, etc., which is capable of operating multiple lines using the accumulated pressure of a pressure accumulator. An injection molding machine, etc. that has multiple pressure accumulator circuits with different accumulated pressures in the hydraulic circuit width, selects one pressure accumulator circuit suitable for each operation as necessary, and releases the pressure. Another object of the present invention is to provide a hydraulic circuit for an injection molding machine, etc., which is a hydraulic circuit, and further adjusts the accumulated pressure of a pressure accumulator in a plurality of pressure accumulator circuits based on the detected value.

Still another object is to provide a hydraulic circuit for not only one molding machine but also two or more molding machines and an injection molding machine in which each operation is controlled by the plurality of pressure accumulator circuits with different accumulated pressures. be.

Next, an embodiment of the present invention will be described in which a hydraulic actuator for screw rotation, injection, and mold opening/closing operations, which are typical operations of an injection molding machine, is driven using three pressure accumulators of high, low, and medium pressure. Taking this as an example and explaining it with reference to FIGS. 1 to 3, 11 is an injection molding machine, and the screw 12 is a hydraulic motor 13.
The heating cylinder 15 is rotatably driven by the injection cylinder 14 and can be moved back and forth in the axial direction by pressure oil acting on the injection cylinder 14.
It is inserted inside. Reference numerals 16 and 17 denote a fixed mold and a movable mold, respectively, in which the movable mold 17 moves forward and backward with respect to the fixed mold 16 by pressure oil applied to a mold clamping cylinder 18, and is connected to the movable mold at the mold joint surface A. When 17 comes into contact with both molds 16
and 17 cooperate to form a cavity. 19 to 21 are pressure accumulators for high pressure, medium pressure, and low pressure, respectively. Numerals 22 to 24 are electromagnetic switching valves for selecting the pressure accumulators 19 to 21, and depending on the switching positions a, b, and intermediate positions, the pressure accumulators 20, 19, and 21 are selected for medium pressure, high pressure, and low pressure, respectively. Pressure is applied to the mold clamping cylinder 18. It is configured to act on the circuits of the injection cylinder 14 and the hydraulic motor 13 (hereinafter referred to as an actuator). Reference numerals 25 to 27 are check valves for isolating the pressure accumulator circuits of the pressure accumulators 19 to 21.

28 to 30 are solenoid valves for actuator switching control.
Reference numeral 8 denotes an electromagnetic switching valve for controlling the drive of the screw 12, which controls opening and closing of the pressure oil released to rotate the hydraulic motor 13 during the metering process. Reference numeral 29 denotes a solenoid valve for switching control of the injection cylinder 14, which switches the pressure oil released into the injection cylinder 14 during the injection process. Reference numeral 30 denotes a solenoid valve for switching control of the mold clamping cylinder 18, which switches the pressure oil applied to the mold clamping cylinder 18 during the mold clamping operation. 31 to 34 are pressure detectors provided in the pressure oil supply section of the actuator, respectively. By providing the detectors 31 to 34 in this way, the load pressure required for each operation can be read, so it is possible to determine how to operate the pressure accumulator selection electromagnetic switching valves 22 to 24 for each actuator according to the value. This selection operation is performed by comparing the detected values of the pressure detectors 31 to 34 with the charge pressures of the pressure accumulators 19 to 21, as shown in FIG. By providing the determination control circuit 35, it is possible to automatically apply the operation signal 35a to the electromagnetic switching valves 22 to 24 to control switching of the switching valves 22 to 24. 36 to 38 are electromagnetic switching valves for charging the hydraulic oil from the pump 39 to the pressure accumulators 19 to 21, respectively, and as shown in FIG. and the detected values of pressure detectors 40 to 42 provided in the pressure accumulators 19 to 21 are compared and calculated, and when the calculated value and the detected value match, the charging operation of the pressure accumulators 19 to 21 is terminated. Switching is controlled by a signal 43a from a circuit 43.

44 is a relief valve 45 for setting the drive pressure of the pump 39.
is a switching valve for controlling the drive pressure of the pump 39.

Since the structure is as explained above, the load acting on each actuator varies depending on the usage conditions such as the type of resin used, the shape of the molded product, and the size of the mold, but it can be used to accommodate various usage conditions. By using high-pressure, medium-pressure, and low-pressure pressure accumulators, the accumulated pressure can be used effectively by driving each pressure accumulator individually or in combination, so there is little wasted energy and the power can be adjusted according to each operation. Accurate operation is possible.

In addition to using one injection molding machine, it is also possible to control the operation of multiple machines.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the present invention. Figures 2 and 3
The figure is an explanatory diagram thereof, and FIG. 2 is a diagram showing a method of controlling a selector valve for a pressure accumulator that acts on an actuator, and FIG. 3 is an explanatory diagram showing a method of charging a pressure accumulator with hydraulic oil from a pump. 11... Injection molding machine, 13... Hydraulic motor, 14...
・Injection cylinder, 18...Mold clamping cylinder, 19...Pressure accumulator for high pressure, 20...Pressure accumulator for medium pressure, 21...Pressure accumulator for low pressure, 22, 23, 24...For pressure accumulator selection Solenoid switching valve, 28.29.30... Solenoid valve for actuator cutting control, 31.32, 33, 34... Pressure detector (for actuator), 36.37.38... Solenoid switching for pressure accumulator charging. Valve, 40°41.42... Pressure detector for pressure accumulator. Applicant: Toshiba Machine Co., Ltd.

Claims (1)

[Scope of Claims] 1. In the hydraulic circuit of an injection molding machine, etc., a plurality of circuits each having a storage device with different storage pressures are provided, and pressure is detected in each operation control circuit for injection, ejection, mold opening/closing, etc. When the pressure detection device detects a predetermined pressure, a pressure accumulator circuit suitable for each operation is selected from the plurality of pressure accumulator circuits, and the accumulated pressure of the same circuit width is released to perform each operation. A hydraulic circuit for an injection molding machine, etc., characterized by being operable and controllable. 2. The scope of the above claims, characterized in that a pressure detection device provided in each operating circuit detects the pressure within the circuit, and replenishes the accumulated pressure of the pressure accumulator in each operating circuit to a predetermined accumulated pressure. A hydraulic circuit for an injection molding machine, etc., as described in item 1. 3. A pressure detection device provided in each operating circuit detects the pressure within the circuit, and selectively releases the accumulated pressure of two or more pressure accumulators. A hydraulic circuit for an injection molding machine, etc., as described in item 2. 4. A hydraulic circuit for an injection molding machine or the like according to claims 1 to 3, wherein the plurality of pressure accumulator circuits are used to control each operation of two or more injection molding machines.