JPH0818361B2 - Hydraulic pump 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 hydraulic pump device for an injection molding machine in which a pump shaft of a hydraulic pump and a motor shaft of a pump motor are connected via a coupling.

[0002]

2. Description of the Related Art Conventionally, a hydraulic pump device using an electromagnetic proportional variable discharge type piston pump for driving and controlling a hydraulic actuator is known, for example, from Japanese Patent Laid-Open No. 62-270803.

A hydraulic pump device of this type is shown in FIG. In the hydraulic pump device 30 of the same drawing, the swash plate angle directly changes according to the magnitudes of the flow rate command signal Sf and the pressure command signal Sp provided from the controller 31, and the discharge is performed corresponding to the swash plate angle. An electromagnetic proportional variable discharge amount type piston pump 32 having variable flow rate and discharge pressure is provided, and a pump shaft 33 and a pump motor 3 of the piston pump 32 are provided.
The motor shaft 35 of 4 is a coupling (transmission joint) 3
It was linked via 6.

[0004]

However, when the conventional hydraulic pump device 30 is used in an injection molding machine, there is a problem that the following adverse effects occur.

First, when operating a hydraulic actuator such as an injection cylinder at high speed or high pressure, it is necessary to use a large-sized pump motor 34 that meets the operating conditions. Increases costs.

Secondly, in the case of the electromagnetic proportional variable discharge type piston pump 32, the swash plate angle is controlled by the flow rate command signal Sf from the controller 31, and the discharge flow rate of the piston pump 32 changes based on this. . Therefore, in the injection process, when the load pressure of the injection cylinder (screw) increases, the load of the pump motor 34 also increases, the slip of the pump motor 34 increases, and the rotation speed of the pump motor 34 decreases and the discharge speed decreases. The flow rate also decreases. However, since this decrease has no effect on the swash plate angle, the discharge flow rate remains reduced and the injection speed cannot be controlled stably and highly accurately.

The present invention has solved the problems existing in the prior art as described above, and it is possible to reduce the size and cost of the injection molding machine and electric power equipment, and to stably and accurately control the speed of the hydraulic actuator. It is an object of the present invention to provide a hydraulic pump device for an injection molding machine, which can be performed at any time.

[0008]

When the present invention constitutes a hydraulic pump device 1 of an injection molding machine in which a pump shaft 2s of a hydraulic pump 2 and a motor shaft 3s of a pump motor 3 are connected via a coupling 4. In particular, it is characterized in that the flywheel 5 having a predetermined weight or more is sandwiched between the couplings 4 (between the coupling halves 4i and 4j) between the pump shaft 2s and the motor shaft 3s.

[0009]

According to the hydraulic pump device 1 of the injection molding machine according to the present invention, the rotation of the motor shaft 3s in the pump motor 3 is transmitted to the pump shaft 2s via the coupling 4 and the flywheel 5, and the hydraulic pump 2 Is driven.

At this time, since the flywheel 5 rotates together with the rotation of the pump shaft 2s, for example, when the hydraulic pump 2 is unloaded during the molding process in the molding cycle, that is, when the hydraulic actuator is not operating, the flywheel is not operated. Rotational energy of the pump motor 3 is accumulated in the wheel 5. As a result, when the hydraulic actuator is operated in the molding process such as the injection process, the flywheel 5 does not respond to the original rotational energy output from the pump motor 3.
Since the rotational energy is transmitted to the hydraulic pump 2 in a state where the rotational energy is added, high speed control or high pressure control is realized even with a small pump motor 3.

Further, even when the load increases corresponding to the screw position during the injection in the injection process, and the slip of the pump motor 3 increases and the rotation speed decreases, the inertia of the flywheel 5 causes In order to suppress the decrease in the rotation speed, the rotation speed is smoothed (the discharge flow rate is made constant), so that the speed control of the hydraulic actuator is stably and accurately performed.

[0012]

Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, a schematic structure of an injection molding machine M including a hydraulic pump device 1 according to the present invention will be described with reference to FIG.

Reference numeral 11 denotes an injection device in the injection molding machine M. The injection device 11 includes a heating cylinder 12 in the front part,
2 has an injection nozzle 13 at the front end and a hopper 14 at the rear. The rear end of the heating cylinder 12 is connected to the front end of the injection cylinder 15, and the screw 1 is attached to the front end of the injection ram 16 provided inside the injection cylinder 15.
Join the rear ends of 7. Then, the front side of the screw 17 is inserted into the heating cylinder 12. 18 is an injection ram 16
Is an oil motor having a rotary shaft 18s spline-coupled to.

On the other hand, C is a hydraulic circuit, which is provided with a hydraulic pump 2 using an electromagnetic proportional variable discharge type piston pump, and this hydraulic pump 2 is connected to a controller 19.
The electromagnetic proportional variable discharge type piston pump has a flow rate command signal Sf and a pressure command signal S applied from the controller 19.
The swash plate angle changes directly and actively according to the magnitude of p, and the discharge flow rate and discharge pressure change according to the swash plate angle. The hydraulic pump 2 and the oil tank 20 are connected to the front oil chamber and the rear oil chamber of the injection cylinder 15 via the four-way switching valve 21.

Further, 2s is a pump shaft of the hydraulic pump 2, and a coupling half 4 similar to the conventional one is provided at the tip thereof.
i is integrally provided. On the other hand, 3 is a pump motor using an induction motor, in which a coupling half body 4j is similarly provided at the tip of the motor shaft 3s, and a disc-shaped weight greater than a predetermined weight is formed between the coupling half bodies 4i and 4j. The flywheel 5 is sandwiched. The coupling halves 4i and 4j are connected to the flywheel 5 by a plurality of fixing bolts 23 ... The pair of coupling halves 4i, 4j form the coupling 4. In this case, the total weight of the flywheel 5 is selected to be a predetermined weight or more in consideration of the size and performance of the hydraulic pump 2 and the pump motor 3.

Next, the function of the hydraulic pump device 1 according to the present invention will be described with reference to FIG.

First, the rotation of the motor shaft 3s in the pump motor 3 is transmitted to the pump shaft 2s via the motor shaft 3s and the flywheel 5, and the hydraulic pump 2 is driven. Then, at this time, the flywheel 5 also rotates together with the rotation of the pump shaft 2s, and when the injection cylinder (hydraulic actuator) 15 is inoperative, the rotational energy of the pump motor 3 is accumulated in the flywheel 5.

Therefore, for example, when the injection cylinder 15 operates in the injection process, the hydraulic pump 2 is supplied with the rotational energy of the flywheel 5 added to the original rotational energy output from the pump motor 3. High-speed control or high-voltage control is realized even with the small pump motor 3 transmitted. Further, at the time of injection in the injection process, the load increases corresponding to the screw position and the slip of the pump motor 3 also increases, but the rotation speed is smoothed by the inertia of the flywheel 5 and the speed control of the injection cylinder 15 is performed. Is stable and highly accurate.

Next, a modified embodiment of the hydraulic pump device 1 according to the present invention will be described with reference to FIG.

A modified embodiment shown in FIG. 2 is a pump shaft 2
A coupling half body 4i similar to the conventional one is integrally provided at the tip of s, and a coupling half body 4j is similarly provided at the tip of the motor shaft 3s. 5, wheel shafts 5s projecting to both sides are integrally provided, and coupling halves 4p and 4q are integrally provided at both ends of the wheel shaft 5s, respectively. Therefore, it is possible to couple the coupling halves 4i and 4p, and further couple the coupling halves 4j and 4q by the plurality of fixing bolts and nuts 24.

A reference example is shown in FIG. In the reference example, a disk-shaped flywheel half body 5i is integrally provided at the tip of the pump shaft 2s, and a disk-shaped flywheel half body 5j is also integrally formed at the tip of the motor shaft 3s. It is provided. Then, the flywheel halves 5i and 5j facing each other have their facing surfaces overlapped with each other, and a plurality of fixing bolt nuts 2
Combined by 2 ... As a result, the pair of flywheel halves 5i and 5j form the flywheel 5. In this case, the total weight of the flywheel 5 is selected in consideration of the sizes and performances of the hydraulic pump 2 and the pump motor 3 so that the flywheel 5 has a predetermined weight or more to exert the flywheel function. The flywheel 5 also serves as the coupling 4. Therefore, this embodiment has an advantage that a separate coupling is unnecessary.

As in the modified embodiment, the form of the flywheel 5, the coupling means, etc. can be arbitrarily modified.

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment,
The detailed configuration, shape, quantity, materials, etc. can be arbitrarily changed without departing from the scope of the present invention.

[0025]

As described above, according to the present invention, in a hydraulic pump device of an injection molding machine in which a pump shaft of a hydraulic pump and a motor shaft of a pump motor are coupled via a coupling, a cup between the pump shaft and the motor shaft is provided. Since a flywheel of a predetermined weight or more is sandwiched between the rings, the injection molding machine and electric power equipment can be downsized and the cost can be reduced, and the speed control of the hydraulic actuator can be performed stably and with high accuracy. It has a remarkable effect that it can be done.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an injection molding machine including a hydraulic pump device according to the present invention,

FIG. 2 is a side view of a flywheel according to a modified embodiment of the hydraulic pump device,

FIG. 3 is a side view of a flywheel according to a reference example,

FIG. 4 is a schematic configuration diagram of a hydraulic pump device according to a conventional technique,

[Explanation of symbols]

 1 Hydraulic Pump Device 2 Hydraulic Pump 2s Pump Shaft 3 Pump Motor 3s Motor Shaft 4 Coupling 5 Flywheel M Injection Molding Machine

Claims (1)

[Claims] 1. A hydraulic pump device for an injection molding machine, comprising a pump shaft of a hydraulic pump and a motor shaft of a pump motor coupled via a coupling, wherein a predetermined weight is provided between the coupling between the pump shaft and the motor shaft. A hydraulic pump device for an injection molding machine, characterized in that the above flywheel is sandwiched and coupled.