JPH059250B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to an injection device movement control method and device for moving the injection device of an injection molding machine using an electric motor as a drive source.

(b) Prior Art A conventional method and device for controlling the movement of an injection device of an injection molding machine is disclosed in Japanese Patent Application Laid-Open No. 63-244206. In a device that uses an electric motor as a drive source to move the injection device back and forth, the injection device to the specified retreat position. The predetermined time period for driving the electric motor is calculated based on the rotational speed of the electric motor and the speed change characteristics of the power transmission mechanism so that the stroke of the injection device reaches a predetermined value. By doing this, there is no need for a position detector such as an encoder,
The injection device can be moved to a desired retracted position.

(c) Problems to be solved by the invention However, in the above-mentioned device in which the injection device is moved back and forth using the electric motor as the drive source,
If the nozzle of the injection device is simply kept in contact with the mold, when resin is injected from the nozzle into the mold, the nozzle will retreat slightly due to the pressure of the injection resin, causing the resin to leak out of the mold. There is. In order to prevent this resin leakage, a force is required to forcibly press the nozzle against the mold, and this is called nozzle touch force. In the case of a motor-driven injection molding machine, this nozzle touch force usually utilizes the force of a spring. For this reason, the drive time of the electric motor required to move the injection device through the set stroke from the state where the nozzle of the injection device is in contact with the mold is simply calculated from the rotational speed of the electric motor and the speed change characteristics of the power transmission mechanism. However, there was a problem in that the nozzle touch force mentioned above affected the nozzle, making it impossible to stop at a predetermined retreat position. The present invention aims to solve these problems.

(d) Means for Solving the Problems The present invention provides a mechanism for releasing the nozzle touch force that operates at a position where the nozzle is in contact with the mold, although the spring that is the source of the nozzle touch force does not apply any force to the nozzle. A limit switch is provided, and after injection molding is performed with the nozzle of the injection device pressed against the mold with a predetermined nozzle touch force, the limit switch that releases the nozzle touch force is activated, and then the necessary stroke is necessary to move the injection device back by a predetermined stroke. The above problem is solved by driving the electric motor for driving the injection device for only a certain amount of time. That is, in the injection device movement control method for an injection molding machine according to the present invention, after injection is performed with the nozzle of the injection device pressed against the mold with a predetermined pressing force, the pressing force of the nozzle is released. , the injection device is moved to a predetermined retreat position by operating the electric motor in the injection device retreat direction for a pre-calculated predetermined time from a state in which the nozzle is in contact with the mold.

Further, the injection device movement control device for an injection molding machine according to the present invention includes power transmission mechanisms 38, 36, 34, 3.
2, 26, 28 and the injection device 10, and the nozzle 14 of the injection device is in contact with the mold 12, but the spring force is not acting on the nozzle. Limit switch 20 for releasing the nozzle touch force that operates at
, an injection device stroke setter 48 that can set the stroke of the injection device, and a driving time of the electric motor required to move the stroke set in the injection device stroke setting device, the rotational speed of the electric motor and the speed of the power transmission mechanism. It has a time calculator 46 that calculates from the characteristics, and a controller 44 that operates the electric motor in the backward direction of the injection device for the time calculated by the time calculator after the nozzle touch force release limit switch is activated. .

(e) Action The limit switch for releasing the nozzle touch force is activated at a position where the nozzle of the injection device is in contact with the mold but the spring force is not acting on the nozzle. The electric motor is driven in the backward direction of the injection device for a predetermined period of time from the time of activation. This moves the injection device to a predetermined retreat position. The predetermined time period for driving the electric motor is calculated based on the rotational speed of the electric motor and the speed change characteristics of the power transmission mechanism so that the stroke of the injection device reaches a predetermined value. Therefore, the injection device can be moved to a desired retracted position without requiring a position detector such as an encoder and without being affected by the nozzle touch force.

(f) Example FIG. 1 shows an example of the present invention. Injection device 10
is movable in the horizontal direction, that is, in the direction toward and away from the mold 12, by means of a slide plate 16 and a mounting plate 18, which will be described later. The injection device 10 has a nozzle 14 at its tip for injecting molten resin. The slide plate 16 that is integrally attached to the injection device 10 is connected to the mounting plate 18.
It is possible to move upwards. A spring chamber 24 with a hole 22 is attached to the end of the slide plate 16 on the nozzle 14 side, and a shaft 26 passes through the hole 22. One end of the shaft 26 is connected to the spring chamber 24
It is fixed to the spring receiver 28 inside. A coiled spring 30 is attached between the spring receiver 28 and the side wall surface of the hole 22 of the spring chamber 24. A ball screw 32 is attached to the other end of the shaft 26.
is attached, and a ball nut 34 is rotatably attached to the ball screw 32. A gear 36 is integrally attached to the outer diameter portion of the ball nut 34, and the gear 36 meshes with a gear 38. Gears 36 and 38, ball nut 3
4. The ball screw 32, the shaft 26, and the spring receiver 28 constitute a power transmission mechanism. The gear 38 can be rotationally driven by an electric motor 40.
By driving the injection device 10, the injection device 10 can be moved left and right via the power transmission mechanism. That is, the gears 38 and 3 are rotated by the rotation of the electric motor 40.
6 rotates to rotate the ball nut 34, move the ball screw 32, shaft 26, and spring receiver 28 in the left and right direction, and move the slide plate 16 and the injection device 10 to the left through the spring 30. without moving the slide plate 16 and the injection device 10 to the right. Limit switches 20 and 21 are attached to the slide plate 16 and are actuated by the horizontal movement of the spring receiver 28. The limit switch 20 for releasing the nozzle touch force is activated when the force of the spring 30 is applied to the nozzle 14.
A limit switch 21 for setting the nozzle touch force is provided at a position that is turned on when the nozzle 14 is in contact with the mold 12 but not acting on the mold 12.
is provided at a position where the spring 30 is turned on with an amount of deflection that generates a predetermined nozzle touch force on the nozzle 14. Electric motor 40 is controlled by switch 42 . The switch 42 is opened and closed by a signal from the controller 44. The controller 44 is actuated by a signal from a time calculator 46 that converts the stroke set by the injection device stroke setter 48 into time as described below.

FIG. 2 shows the state in which the spring 30 is fully compressed. The spring receiver 28 can apply the maximum nozzle touch force to the nozzle 14 when moved to the position shown by the solid line in the figure. Further, at the position indicated by the broken line, no pressing force is applied to the nozzle 14, but the nozzle 14 is in contact with the mold 12. Therefore, the nozzle touch force can be changed within the range of dimension L. If this change is necessary, turn the nozzle touch force setting limit switch 21.
You will need to adjust the mounting position.

Next, the operation of this embodiment will be explained. When the electric motor 40 is driven, the slide plate 16 and the injection device 10 move forward due to the action of the power transmission mechanism, and the nozzle 14 comes into contact with the mold 12 as shown in the figure. When the electric motor 40 is further rotated from this state, the ball screw 32 moves to the left, and the spring 30 is compressed by the spring receiver 28. spring 3
0 reaches the position where it is compressed to a force equivalent to the nozzle touch force, at the same time the spring receiver 28 hits the limit switch 21 for setting the nozzle touch force,
The injection operation is started by the signal from now on, and molten resin is injected into the mold 12. It should be noted that during the injection operation of the injection device 10, the electric motor 40 may be braked by an electromagnetic brake (not shown), or may remain in an excited state. Next, when the controller 44 switches the switch 42 and drives the electric motor 40 in the backward direction of the injection device 10, the ball screw 3
2. The shaft 26 and spring receiver 28 move to the right and hit the limit switch 20 to release the nozzle touch force. This is the position where the spring 30 is released from the amount of deflection determined by the nozzle touch force setting. Timing is started from this point, and the electric motor 40 is further driven for a predetermined time t (seconds). This time t is the stroke l set in the injection device stroke setting device 48.
(mm) by the time calculator 46.
That is, when the stroke l from the state shown in FIG. 1 to the position where the injection device 10 is retreated and stopped is set in the injection device stroke setter 48, the time calculator 46 calculates the rotational speed of the electric motor 40, the ball nut 34, and the ball screw. 32 pitches and gears 3
The drive time t of the electric motor 40 required to move the injection device 10 by the stroke l from the gear ratios 6 and 38 is calculated. The controller 44 controls the switch 42 to energize the electric motor 40 for this time t. As a result, the injection device 10 starts to retreat,
It stops when time t has elapsed. At that point, the injection device 10 will move back by a stroke l. Then, when the mold 12 is clamped in the next cycle, the injection device 10 moves forward in the direction of the mold 12 again and repeats the same operation as described above. As described above, by driving the electric motor 40 for the predetermined time t calculated by the time calculator 46, the injection device 10 can be stroked to a predetermined retreat position. For this reason, a special position detector for detecting the position of the injection device 10 is not required.

(G) Effects of the Invention As described above, according to the present invention, the driving time of the electric motor required to stroke the injection device by a predetermined amount is calculated, and after the injection is completed, the nozzle touch force is released and the nozzle is Since the electric motor is driven for this amount of time from the position where it contacts the mold, that is, the position where the limit switch for releasing the nozzle touch force is hit, the potentiometer,
The stroke of the injection device can now be adjusted without the need for an expensive position detector such as an encoder, and the stroke of the injection device can be set remotely. Furthermore, since the injection device starts retracting after the nozzle touch force acting on the nozzle is released, it is possible to accurately set the retracting position.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view of an embodiment of the present invention;
FIG. 2 is a partial sectional view of the slide plate showing a state in which the spring is fully compressed. 10... Injection device, 12... Mold, 14... Nozzle, 16... Slide plate, 18... Mounting plate, 20... Limit switch for releasing nozzle touch force, 21... Limit switch for setting nozzle touch force, 24... Spring chamber, 26...shaft, 2
8...Spring receiver, 30...Spring, 3
2...Ball screw, 34...Ball nut, 40
...Electric motor, 44...Controller, 46...Time calculator, 48...Stroke setting device.

Claims (1)

[Claims] 1. An injection device movement control method for an injection molding machine in which the injection device is moved back and forth using an electric motor as a drive source,
After injection is performed with the nozzle of the injection device pressed against the mold with a predetermined pressing force, the pressing force of the nozzle is released but the nozzle is still in contact with the mold, and then the pre-calculated predetermined amount is applied. A method for controlling the movement of an injection device of an injection molding machine, characterized in that the injection device is moved to a predetermined retreat position by operating an electric motor in the injection device retreat direction for a certain amount of time. 2. An injection molding machine that uses an electric motor as a drive source to move an injection device back and forth, in which the injection device is moved forward from the drive source via a power transmission mechanism and a spring, while the injection device is moved forward only through the power transmission mechanism without using a spring. In an injection device movement control device for an injection molding machine configured to move backward, the spring does not apply force to the nozzle of the injection device, but is a limit switch for releasing the nozzle touch force that operates at a position where the nozzle is in contact with the mold. , an injection device stroke setting device that can set the stroke of the injection device, and the driving time of the electric motor required to move the stroke set in the injection device stroke setting device from the rotational speed of the electric motor and the speed change characteristics of the power transmission mechanism. Injection molding characterized by having a time calculator for calculating, and a controller for operating the electric motor in the backward direction of the injection device for the time calculated by the time calculator after the nozzle touch force release limit switch is activated. Machine injection device movement control device.