JPH0582514U - Hydraulic circuit of injection cylinder in injection molding machine - Google Patents

Abstract

(57) [Abstract] [Purpose] It is not necessary to adjust the flow rate of hydraulic oil when switching between automatic and manual operation. [Structure] An electromagnetic switching valve 12 provided between a retreating side cylinder chamber 1a of an injection cylinder 1 and a hydraulic pump 5 has three positions and four ports. The first pipe 13 is connected to the A port of the electromagnetic switching valve 12, and the second pipe 14 is connected to the B port. A check valve 15 and a variable throttle valve 16 are provided in parallel with each other in the second pipe 14. The solenoid a of the electromagnetic switching valve 12 is turned on when the internal pressure is removed in the automatic operation, and the solenoid b of the switching valve 12 is turned on in the supply step of the manual operation. The hydraulic oil flows through the pipe 13 in the former case and the pipe 14 in the latter case, and is fed into the retreat side cylinder chamber 1a. Since the pipes 13 and 14 are separately provided in this way, it is not necessary to readjust the flow rate of the hydraulic oil when switching between automatic and manual switching.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a hydraulic circuit of an injection cylinder, which is mainly applied to a small injection molding machine.

[0002]

[Prior Art]

 A hydraulic circuit for an injection cylinder in a small injection molding machine is known as shown in FIG. That is, reference numeral 1 in FIG. 2 is an injection cylinder. The injection cylinder 1 moves the injection screw 3 inserted in the heating cylinder 2 forward and backward (left and right in FIG. 2). A hydraulic pump 5 is connected to the retreating cylinder chamber 1a of the injection cylinder 1 via an electromagnetic switching valve 4, and a hydraulic pump 5 is connected to the advancing cylinder chamber 1b via another electromagnetic switching valve 6. There is. A variable throttle valve 7 is provided between the hydraulic pump 5 and the electromagnetic switching valve 4, and a hydraulic motor 8 is connected to the hydraulic pump 5 via an electromagnetic switching valve 6. The hydraulic motor 8 rotates the injection screw 3 in the circumferential direction. Reference numeral 9 is a nozzle and 10 is a mold.

In the injection molding machine having the hydraulic circuit described above, in the automatic operation, the solenoid a of the electromagnetic switching valve 6 is turned on in the injection process, and the injection screw 3 advances to the left in the drawing and is ejected from the nozzle 9. Resin is injected into the mold 10. In the automatic supply process, the solenoid b of the electromagnetic switching valve 6 is turned on and the hydraulic motor 8 operates to rotate the injection screw 3. Further, when automatically removing the internal pressure of the heating cylinder 2, the solenoid b of the electromagnetic switching valve 4 is turned on, and the injection screw 3 retracts.

The injection molding machine is usually manually operated when it is started up or the resin is changed. In the case of manual operation, switching of both electromagnetic switching valves 6 and 4 in the injection process and removal of internal pressure is the same as in automatic operation, but in the supply process, solenoid b of electromagnetic switching valve 6 is turned on and The solenoids of the other solenoid operated directional control valves 4 are also turned on to retract the ejection screw 3. The reason for operating in this way is that, in the case of starting up or changing the resin, the nozzle 9 of the heating cylinder 2 is separated from the mold 10, and in the case of a small injection molding machine having an injection screw 3 with a small diameter, Since the relationship between the plasticizing ability of the injection screw 3 and the nozzle hole diameter and the mechanical sliding resistance of the injection screw 3 do not fall below a predetermined value, the injection screw 3 is less likely to retract, and as a result, the resin leaks from the nozzle 9. Is to generate.

[0005]

[Problems to be solved by the device]

 As can be understood from the above description, in the conventional hydraulic circuit, the hydraulic oil flows through the same circuit for removing internal pressure during automatic operation and during the supply process during manual operation, and the retreating cylinder chamber of the injection cylinder 1 It is sent to 1a. For this reason, when operating manually, the variable throttle valve 7 is adjusted to make the reverse speed of the injection cylinder 1 appropriate, but when shifting to automatic operation, the variable throttle valve 7 is readjusted and returned to its original state. It must be done, which is very annoying and inconvenient.

An object of the present invention is to provide a hydraulic circuit of an injection cylinder in an injection molding machine, which does not require adjustment of a variable throttle valve when switching from automatic operation to manual operation and from manual operation to automatic operation. To do.

[0007]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, according to the present invention, a hydraulic pump is connected through a first electromagnetic switching valve to a retreat side cylinder chamber of an ejection cylinder for advancing and retreating an injection screw and a forward movement of the injection cylinder. In the hydraulic circuit of the injection cylinder in which the hydraulic pump is connected to the side cylinder chamber via the second electromagnetic switching valve, the first electromagnetic switching valve is substantially a 3-position 4-port electromagnetic switching valve, and the first electromagnetic switching valve is also used. The switching valve is connected to the oil tank when the first electromagnetic switching valve is neutral, and to the hydraulic pump when one solenoid of the first electromagnetic switching valve is turned on, and the first electromagnetic switching valve. The first pipe that is shut off when the other solenoid is turned on, and the oil tank is connected when the first electromagnetic switching valve is neutral, and one solenoid of the first electromagnetic switching valve is turned on. In case A second pipe that is connected to the hydraulic pump when the other solenoid of the first electromagnetic switching valve is turned on and is turned on is connected to the rearward and backward cylinder chamber of the injection cylinder, and to the second pipe. A non-return valve that frees the flow of hydraulic oil from the reverse side cylinder chamber to the first electromagnetic switching valve and stops the reverse flow, and a variable that adjusts the flow rate of hydraulic oil that flows from the first electromagnetic switching valve to the reverse side cylinder chamber. The throttle valve was installed in parallel.

[0008]

[Action]

 When the internal pressure is removed in the automatic operation, one solenoid of the first electromagnetic switching valve is turned on, and the hydraulic oil is sent to the retreating cylinder chamber of the injection cylinder through the first pipe. Also, in the supply process during manual operation, the other solenoid of the first electromagnetic switching valve is turned on, and hydraulic oil is sent to the reverse side cylinder chamber of the injection cylinder through the second pipe. In this way, since different pipes are used in the internal pressure removal in automatic operation and the supply process in manual operation, it is not necessary to adjust the variable throttle valve individually.

[0009]

【Example】

 FIG. 1 shows an embodiment of the present invention. In the hydraulic circuit of FIG. 1, portions corresponding to those of FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

The electromagnetic switching valve 12 provided between the retreating cylinder chamber 1 a of the injection cylinder 1 and the hydraulic pump 5 is a 3-position 4-port electromagnetic switching valve. The A port of the electromagnetic switching valve 12 is connected to the retreat side cylinder chamber 1a of the injection cylinder 1 by the first pipe 13, and the B port is connected to the retreat side cylinder chamber 1a by the second pipe 14. The second pipe 14 flows from the solenoid switching valve 12 to the retreat side cylinder chamber 1a, and the check valve 15 that allows the working oil to flow from the retreat side cylinder chamber 1a to the solenoid changeover valve 12 to stop the reverse flow. A variable throttle valve 16 for adjusting the flow rate of hydraulic oil is provided in parallel.

Explaining the relationship between the electromagnetic switching valve 12 and the pipes 13 and 14 here, when the electromagnetic switching valve 12 is in the neutral position, both the pipes 13 and 14 are connected to the oil tank, and the electromagnetic switching valve 12 has When one solenoid a is excited, the first pipe 13 is connected to the hydraulic pump 5, the second pipe 14 is cut off, and when the other solenoid b of the electromagnetic switching valve 12 is excited (the solenoid a is turned on). Needless to say, demagnetization is performed.) The first pipe 13 is cut off, and the second pipe 14 is connected to the hydraulic pump 5. Reference numeral 17 is a relief valve.

Next, the operation of the hydraulic circuit of the injection cylinder in the injection molding machine configured as described above will be described. The solenoid a of the electromagnetic switching valve 6 is turned on in the injection process of the automatic operation, and the solenoid b of the electromagnetic switching valve 6 is turned on in the supply process of the automatic operation, as in the conventional hydraulic circuit of FIG. is there. When automatically removing the internal pressure of the heating cylinder 2, the solenoid a of the electromagnetic switching valve 12 is turned on. As a result, the hydraulic oil of the hydraulic pump 5 is sent to the retreat side cylinder chamber 1a of the injection cylinder 1 through the first pipe 13, and causes the injection screw 3 to retreat.

Further, the switching of both electromagnetic switching valves 6 and 12 in the injection process of the manual operation and the removal of the internal pressure is the same as in the automatic operation. However, in the manual supply process, the solenoid b of the electromagnetic switching valve 6 is turned on and the solenoids b of the other electromagnetic switching valves 12 are also turned on. By this operation, the injection screw 3 is rotated in the circumferential direction by the hydraulic motor 8 to plasticize the resin, and is retracted by the injection cylinder 1 which is moved by the hydraulic oil flowing through the variable throttle valve 16 of the second pipe 14.

[0014]

[Effect of the device]

 The hydraulic circuit of the injection cylinder in the injection molding machine of the present invention is configured as described above, and in the internal pressure removal during automatic operation and the supply step during manual operation, hydraulic oil flows through different pipes to retreat the injection cylinder. Since it is sent to the side cylinder chamber, it is not necessary to readjust the throttle valve each time the injection molding machine is switched from automatic operation to manual operation or from manual operation to automatic operation. For this reason, it is possible to perform the molding work efficiently without any trouble.

[Brief description of drawings]

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

FIG. 2 is a diagram of a conventional hydraulic circuit.

[Explanation of symbols]

 1 Injection Cylinder 1a Retraction Side Cylinder Chamber 1b Forward Side Cylinder Chamber 3 Injection Screw 5 Hydraulic Pump 6 Electromagnetic Switching Valve 12 Electromagnetic Switching Valve a Solenoid b Solenoid 13 First Pipe 14 Second Pipe 15 Check Valve 16 Variable Throttle Valve

Claims (1)

[Scope of utility model registration request] 1. A hydraulic pump is connected to a retreat side cylinder chamber of an injection cylinder for advancing and retreating an injection screw back and forth through a first electromagnetic switching valve, and the hydraulic pump is provided to a forward side cylinder chamber of the injection cylinder. In the hydraulic circuit of the injection cylinder connected via the two electromagnetic switching valves, the first electromagnetic switching valve is substantially a three-position four-port electromagnetic switching valve, and the first electromagnetic switching valve is the first electromagnetic switching valve. When the oil tank is connected when the valve is neutral, and when one solenoid of the first electromagnetic switching valve is turned on, the hydraulic pump is connected and the other solenoid of the first electromagnetic switching valve is turned on To the oil tank when the first electromagnetic switching valve is in the neutral state, and is shut off when the one solenoid of the first electromagnetic switching valve is turned on, and the first electromagnetic switching is performed. A second pipe connected to the hydraulic pump when the other solenoid of the valve is turned on is connected to the retreat side cylinder chamber of the injection cylinder, and the second pipe is connected to the retreat side cylinder chamber from the first electromagnetic chamber. A check valve for freeing the flow of hydraulic oil to the switching valve and stopping the reverse flow thereof and a variable throttle valve for adjusting the flow rate of hydraulic oil flowing from the first electromagnetic switching valve to the backward cylinder chamber are provided in parallel. A hydraulic circuit of an injection cylinder in an injection molding machine, which is characterized in that