JPH0131458Y2 - - Google Patents

Description

[Detailed explanation of the idea] (b) Industrial application fields The present invention relates to an injection device.

(b) Prior Art An injection molding machine has an injection unit that injects molten resin into a mold. Before injection, the injection unit waits at a position away from the mold, moves forward during injection to come into contact with the mold, injects molten resin from the nozzle, and then retreats to the initial position again. This movement of the injection unit has conventionally been effected by a hydraulic cylinder. That is, a hydraulic cylinder having a necessary stroke and pushing force is connected to the injection unit, and the injection unit is moved forward and backward by controlling the operation of the hydraulic cylinder. The same pressure as the injection hydraulic pressure of the injection unit is applied to the hydraulic cylinder, thereby obtaining a nozzle pressing force corresponding to the injection force.

(c) Problems that the invention aims to solve Conventional injection devices such as those described above use hydraulic cylinders, which tend to cause wear and tear on packings, seal members, etc., and therefore require periodic replacement. Further, if oil leakage occurs, the operation must be stopped, and there are many factors that reduce productivity. The present invention aims to solve the above problems.

(d) Means for solving the problem The present invention electrifies the injection of molten resin from the injection unit, the movement of the injection unit, and the action of the nozzle pressing force, and also provides a nozzle pressing force commensurate with the injection force. The above problem is solved by controlling the electric motor so that That is, the injection device according to the present invention includes an injection unit capable of injecting molten resin using an injection motor, an injection unit driving motor capable of moving the injection unit forward and backward via a ball screw mechanism, and an injection unit capable of injecting molten resin using an injection motor. It has a load detector that detects the load on the electric motor, and a pressing force controller that controls the power supplied to the injection unit driving electric motor according to the load on the injection motor detected by the load detector. There is.

(e) Operation By operating the injection unit driving electric motor, the injection unit is advanced toward the mold via the ball screw mechanism, and the nozzle is brought into contact with the mold. Next, the injection motor is activated and the molten resin is injected from the nozzle into the mold. At the same time, the load (e.g., current) on the injection motor is detected by a load detector (e.g., a current detector). The pressing force controller controls the electric power supplied to the injection unit driving motor accordingly. Therefore, as the injection force increases, the nozzle pressing force increases, and stable injection can be performed without causing resin leakage.

(F) Embodiments Hereinafter, embodiments of the present invention will be described based on FIGS. 1 to 5 of the accompanying drawings.

A support base 14 is mounted on the bed 10 by bolts 12.
is fixed. Two horizontal guide shafts 16 are attached between two vertical walls 14a of the support base 14, and an injection unit 18 is supported on these so as to be movable in the axial direction. That is, the injection unit 18 connects to the guide shaft 1 via bushes 20 and 22 provided on its bracket portions 18a and 18b.
It is possible to slide on 6. The injection unit 18 has a cylinder 2 containing a screw 19 (see Fig. 3).
4 and a nozzle 26 at its tip. The injection unit 18 also has an injection motor 27 that can control the injection force of the molten resin from the nozzle 26. A screw shaft 34 rotatably supported by radial bearings 28 and 30 and a thrust bearing 32 is provided between the vertical walls 14a of the support base 14. A male thread forming a ball screw mechanism is provided on the outer periphery of the screw shaft 34. The screw shaft 34 can be rotated by an injection unit driving electric motor 38 having a pulse generator 36. A nut member 40 is assembled to the screw shaft 34. The nut member 40 has a female thread that constitutes a ball screw mechanism together with a male thread on the outer periphery of the screw shaft 34. The nut member 40 is the injection unit 1
It is attached to the bracket portion 18c of No. 8 with a bolt 42.

FIG. 4 shows a control system for the injection motor 27 and the injection unit driving motor 38. The injection pressure controller 50 can control the current supplied from the drive circuit 52 to the injection motor 27. The pressing force controller 54 is connected to the injection unit driving electric motor 3 from the drive circuit 56.
8 can be controlled. The load current of the injection motor 27 is detected by a current detector 5 which is a load detector.
8, the signal is processed by a transducer 60 and input to the pressing force controller 54.

Next, the operation of this injection device will be explained.
FIG. 1 shows the injection unit 18 in the most retracted state (that is, the injection unit 18 is at the farthest position from the mold 70), where the nozzle 26 and the injection hole 70a of the mold 70 are connected. The distance between
It is becoming. In this state, when the injection unit driving electric motor 38 is operated and the screw shaft 34 is rotated, the nut member 40 cannot be rotated and moves forward in the axial direction (moves to the left in FIG. 1). As a result, the injection unit 18 integrated with the nut member 40 also moves forward. In this way, injection unit 1
8 moves forward by a distance S, the nozzle 26 moves toward the mold 70.
contacts the injection hole 70a. This state is shown in FIG. Note that the fact that the injection unit 18 has moved forward by the distance S is confirmed by the signal from the pulse generator 36. Next, in the state shown in FIG. 2, the drive circuit 5 is activated based on a command from the injection pressure controller 50.
The injection motor 27 is
rotates, the screw 19 inside the cylinder 24 moves forward, and molten resin is injected. At the same time, the load current of the injection motor 27 is detected by the current detector 58 and inputted to the pressing force controller 54 via the converter 60. The pressing force controller 54 inputs a predetermined signal to the drive circuit 56 in response to the signal input from the converter 60. As a result, a predetermined current is supplied to the injection unit driving motor 38,
The injection unit driving electric motor 38 generates a torque corresponding to the current, and presses the nozzle 26 against the injection hole 70a of the mold 70 via the screw shaft 34 and the nut member 40. The pressing force of this nozzle 26 is proportional to the current supplied to the injection unit drive motor 38. Therefore, the pressing force of the nozzle 26 increases or decreases in accordance with the increase or decrease in the injection force of the molten resin generated by the injection motor 27. The relationship between the injection force and the nozzle pressing force is, for example, as shown in FIG. After the injection is completed, the injection motor 27 is stopped, the injection unit drive motor 38 is rotated in the opposite direction to the above to release the nozzle pressing force, and the injection unit 18 is then retreated, as shown in FIG. restore the condition. In this embodiment, the power supplied to the injection unit driving motor is controlled by controlling only the current, but it is clear that the voltage or both the current and the voltage may be controlled. be.

(g) Effects of the invention As explained above, according to the invention, the injection of molten resin, the movement of the injection unit, and the action of the nozzle pressing force are motorized, and during injection, the injection is controlled according to the load of the injection motor. Since the power of the electric motor for driving the unit is controlled, it is possible to always obtain an appropriate nozzle pressing force in accordance with the injection force, thereby eliminating problems associated with using a hydraulic system.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an injection device according to the present invention;
The figure shows a state in which the nozzle of the injection device shown in FIG. 1 is in contact with the mold, FIG. 3 is a sectional view of the injection device shown in FIG. 1 taken along the - line, and FIG. 4 is a view showing the control device. , FIG. 5 is a diagram showing the relationship between injection force and nozzle pressing force. 18... Injection unit, 26... Nozzle, 27... Injection motor, 34... Screw shaft, 38... Injection unit drive motor, 40... Nut member, 50... Injection pressure controller, 54... Pushing force controller, 58... Current Detector (load detector).

Claims (1)

[Scope of utility model registration request] An injection unit that can inject molten resin using an injection motor, an injection unit drive motor that can move the injection unit forward and backward via a ball screw mechanism, and a load detector that detects the load on the injection motor. and a pressing force controller that controls power supplied to the injection unit driving motor according to the load of the injection motor detected by a load detector.