JPH0111453Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a mold clamping device for an injection molding machine.

(B) Prior Art There are two types of mold clamping devices for conventional injection molding machines: a direct pressure type mold clamping device and a toggle type mold clamping device.
A direct pressure mold clamping device uses a large-diameter hydraulic cylinder to directly press the movable platen, and a toggle-type mold clamping device uses a toggle mechanism to double the pushing force of a relatively small-diameter hydraulic cylinder. It is designed to press the movable platen by force.

(c) Problems that the invention aims to solve However, the mold clamping devices of conventional injection molding machines as described above are all driven using hydraulic pressure, and a seal is used to seal the hydraulic pressure. , sealing members, etc. are used, and these parts wear out as they are used, so it is necessary to periodically replace the parts, and in some cases, oil leakage accidents may occur and operation may be stopped. However, there were some aspects where productivity was not sufficient. Furthermore, since it is necessary to arrange a relatively large hydraulic cylinder, the overall length of the mold clamping device becomes long, resulting in a problem that the device becomes larger. The present invention solves the above-mentioned problems, eliminates the need for periodic replacement of gaskets, eliminates the need to stop the equipment due to oil leakage accidents, etc., and provides a mold clamping device for injection molding machines with a more compact structure. The purpose is to obtain.

(d) Means for solving the problems The present invention achieves the above object by operating a mold clamping device using a mold clamping electric motor and a mold opening/closing electric motor. That is, the mold clamping device of the injection molding machine according to the present invention includes a fixed plate and an end housing fixed on a bed so as to face each other at a predetermined interval, and a fixed plate and an end housing that are rotatably attached to the fixed plate and the end housing. a movable platen to which are attached four tie bars having male threads of a ball screw mechanism on the outer periphery, four nut members each having a female thread of a ball screw mechanism that engages with the male threads of the four tie bars; and an end housing. Or a mold clamping electric motor installed on the bed, and a mold clamping worm gear reduction mechanism that can decelerate the rotation of the mold clamping electric motor and transmit it at low speed and high torque to four tie bars and drive them to rotate in a synchronized state. , a clutch that can switch between transmitting and cutting off the rotational force between the mold clamping electric motor and the tie bar, a mold opening/closing electric motor installed on the end housing or bed, and a mold opening/closing electric motor that transmits the rotational force of the mold opening/closing electric motor at high speed and small. It has a mold opening/closing drive mechanism that can transmit torque to four tie bars and drive them to rotate in a synchronized state.

(e) Effect With the above configuration, the mold can be opened and closed at high speed by controlling the rotational direction of the mold opening/closing motor, and the mold can be opened and closed by operating the mold clamping motor. It is possible to add and remove clamping force. Therefore, sufficient mold clamping force can be applied at high speed cycles without using a large-capacity electric motor.

(F) Embodiments Hereinafter, embodiments of the present invention will be described based on FIGS. 1 to 4 of the accompanying drawings.

A fixed platen 12 and an end housing 14 are fixed onto the bed 10 by bolts 16 and 18, respectively. The fixed platen 12 and the end housing 14 are arranged in parallel so as to face each other with a predetermined spacing therebetween. Four tie bars 20 for fixed platen 12 and end housing 14
is rotatably supported. The tie bar 20 is
As shown in FIGS. 2 and 4, they are placed at each corner of the stationary platen 12 and the end housing 14 (that is, placed at each vertex of a square).
The tie bar 20 connects the bearing 2 to the fixed plate 12.
2, and is rotatably supported by tie bar 2.
The normal force acting to the left in FIG. The thrust bearing 24 is connected to the fixed plate 12,
Nut 2 screwed into the screw at the end of tie bar 20
It is located between 6 and 6. Note that the nut 26 is prevented from loosening by a lock nut 28.
The other end of the tie bar 20 is connected to the end housing 1
4 by a bearing 30 so as to be rotatable. Bearing 30 is held to end housing 14 by metal fittings 32. A male thread 34 of a ball screw mechanism is formed on the outer periphery of the tie bar 20. Each male thread 34 has
A nut member 36 having an internal thread constituting a ball screw mechanism is engaged with the nut member 36. Four nut members 36 are fixed to a movable platen 38. Movable plate 38
has a hole 38a through which the tie bar 20 passes, and is movable in the axial direction of the tie bar 20 by rotating the male screw 34. A movable mold 40 is attached to the movable platen 38, while a fixed mold 42 is attached to the fixed platen 12. A mold opening/closing electric motor 61 and a mold clamping electric motor 44 are attached to the end housing 14, as shown in FIGS. 3 and 4, respectively. As shown in FIG. 4, a mold clamping electric motor 44 attached to the end housing 14 by a bracket 70 is connected to an electromagnetic brake 4.
6 and a pulse generator 50. The gear 72 that is rotationally driven by the mold clamping electric motor 44 is
It meshes with two gears 74. two gears 74
are connected to rotate together with two rotating shafts 78, each of which is rotatably supported by a bracket 76. Two worms 80 are provided on each rotating shaft 78. Each worm 80
are the tie bar 20 and the electromagnetic clutch 82, respectively.
It engages with a worm wheel 84 which can be connected via a worm wheel 84 (see FIG. 1). gear 72, gear 7
4. The rotating shaft 78, the worm 80, and the worm wheel 84 constitute a worm gear reduction mechanism for mold clamping. The mold opening/closing electric motor 61 includes a pulse generator 62 and an electromagnetic brake 63.
The rotational force of the mold opening/closing electric motor 61 is generated by a drive gear 66,
The power is transmitted to the tie bar 20 by a mold opening/closing drive mechanism composed of an intermediate gear 53 and four driven gears 54. That is, a drive gear 66 is attached to the rotary shaft 61a of the mold opening/closing electric motor 61 by a key 68, and driven gears 54 are attached to the tie bars 20 by keys 60, respectively. and 4
The driven gears 54 mesh with the intermediate gear 53 at the same time. Note that the shaft 53a of the intermediate gear 53 has bearings 70 and 72 in the center of the housing 14.
is rotatably supported by.

Next, the operation of this embodiment will be explained. In the mold opening state, the movable platen 38 is stopped at the position indicated by the imaginary line in FIG. When closing the mold from this state, the electromagnetic brake 63 is released to rotate the mold opening/closing electric motor 61, and the mold opening/closing drive mechanism,
That is, the four tie bars 20 are rotated at high speed and with small torque in a synchronized state via the drive gear 66, intermediate gear 53, and driven gear 54. As a result, the movable platen 38 moves toward the fixed platen 12. In addition,
At this time, the electromagnetic clutch 82 is released and the worm wheel 84 is not rotated. In this way, the movable platen 38 is moved until the movable mold 40 contacts the fixed mold 42. The rotational position of the mold opening/closing motor 61 when the movable mold 40 comes into contact with the fixed mold 42 is set in advance on a setting device (not shown), and this set value and the signal from the pulse generator 62 match. When this occurs, the mold opening/closing motor 61 is stopped. (The opening/closing electric motor 61 may be stopped.) The movable mold 40 contacts the fixed mold 42 and the mold opening/closing electric motor 6
1 stops, the electromagnetic clutch 82 is engaged so that the worm wheel 84 and tie bar 20 rotate together. Next, the mold clamping electric motor 44 is rotated, and the mold clamping worm gear reduction mechanism, that is, the gear 72, the gear 74, the rotating shaft 78, and the worm 8
0 and the four tie bars 20 are driven in a synchronized state at low speed and large torque via the worm wheel 84. The movable platen 38 is moved by the action of the ball screw mechanism.
is pressed against the fixed platen 12 side, and the fixed mold 42 and the movable mold 40 are tightened with a large force. When the signal detected by the pulse generator 50 reaches a preset value, the electromagnetic brake 46 is activated to brake and stop the mold clamping motor 44, and the current to the mold clamping motor 44 is stopped. Stop the supply and stop the rotation. The predetermined setting value is a value at which a predetermined mold clamping force is generated between the fixed mold 42 and the movable mold 40. As a result, when a predetermined mold clamping force is generated, the electromagnetic brake 4
6, the tie bar 20 is in a stopped state (note that the fact that the mold clamping force between the fixed mold 42 and the movable mold 40 has reached a predetermined value is detected from the load current of the mold clamping motor 44. ). FIG. 1 shows the state in which the mold clamping is completed in this manner.

When the mold clamping is completed as described above, the molten resin is injected, followed by plasticization and cooling of the molded product. During this time, a force is applied by the resin pressure in the direction of opening the mold (that is, to the left with respect to the movable platen 38 in FIG. 1), but the electromagnetic brake 46 is operating, and the ball screw and worm gear Since it has the function of not being able to be driven from the opposite direction, a predetermined mold clamping force is maintained. When cooling of the molded product is completed, the electromagnetic brake 46 is deactivated, and the mold clamping motor 44 is rotated in the opposite direction to that in the above case. As a result, the mold clamping force applied to the movable platen 38 is gradually removed. When the mold clamping force becomes 0 (that is, when the movable mold 40 and the fixed mold 42 come into contact with each other under no load), the mold clamping motor 44 is stopped and the electromagnetic clutch 82 is released, causing the worm wheel 84 and the tie bar 20 to be connected. Unlink. Detection that the mold clamping force has become zero is performed based on a signal from the pulse generator 50. Next, the mold opening/closing electric motor 61 is rotated in the opposite direction to that in the above case. As a result, the movable platen 38 moves to the left in FIG. 1, and when it reaches a predetermined position (the position indicated by the imaginary line), it is stopped by the action of the electromagnetic brake 63. Note that whether the movable platen 38 has reached a predetermined position is determined based on the signal from the pulse generator 62. This completes the mold opening and the molded product is taken out from the mold. This completes one cycle, and the same cycle as described above is repeated.

The mold clamping device of this injection molding machine performs the mold clamping operation and the mold opening/closing operation using the mold clamping electric motor 44 and the mold opening/closing electric motor 61 as described above, and does not use a hydraulic cylinder. No problems such as wear and tear on parts, oil leaks, etc. will occur. Also,
Since the mold clamping electric motor 44 and the mold opening/closing electric motor 61 can control the stroke, moving speed, and mold clamping force of the movable platen 38, these can be easily controlled as desired by a general controller. becomes possible. In this embodiment, the mold opening/closing motor 61 is provided with a pulse generator 62, but instead of this, the movement of the movable platen 38 is directly detected by a linear encoder provided on the bed 10. You can also do that. The mold clamping electric motor 44 and the mold opening/closing electric motor 61 can also be arranged on the bed 10.

(g) Effects of the invention As explained above, according to the invention, the mold clamping operation and the mold opening/closing operation are performed by the mold clamping electric motor and the mold opening/closing electric motor, thereby eliminating the need for a hydraulic cylinder. First, periodic replacement of packings, seal members, etc. is no longer necessary, oil leakage accidents, etc. can be prevented from occurring, and furthermore, since a hydraulic cylinder is not required, the entire mold clamping device can be downsized. Furthermore, by using two electric motors for mold clamping and mold opening/closing, and by using a worm gear speed reduction mechanism for mold clamping, it is possible to perform the necessary operations with a small electric motor.
Does not require a large capacity electric motor. Therefore, the mold clamping device can be made smaller and cheaper, and the required power can be saved.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing one embodiment of the present invention, Fig. 2 is a sectional view taken along the - line in Fig. 1, Fig. 3 is a sectional view taken along the - line in Fig. 2, and Fig. 4 is a sectional view taken along the - line in Fig. 1. It is a figure seen in the arrow direction. 10...Bed, 12...Fixed plate, 14...End housing, 16, 18...Bolt, 20...
... Tie bar, 22 ... Bearing, 24 ... Thrust bearing, 26 ... Nut, 28 ... Lock nut, 30 ... Bearing, 32 ... Metal fitting,
34...Male thread, 36...Nut member, 38...
Movable plate, 40...Movable type, 42...Fixed type, 44
... Mold clamping electric motor, 46 ... Electromagnetic brake, 50
... Pulse generator, 53 ... Intermediate gear, 54 ...
Driven gear, 61... Motor for mold opening/closing, 62... Pulse generator, 63... Electromagnetic brake, 66... Drive gear, 72, 74... Gear, 78... Rotating shaft,
80... Worm, 82... Electromagnetic clutch, 84
...Worm wheel.

Claims (1)

[Scope of utility model registration request] A fixed plate and an end housing fixed on the bed so as to face each other at predetermined intervals, and four pieces rotatably attached to the fixed plate and the end housing and having a male thread of a ball screw mechanism on the outer periphery. A tie bar, a movable platen having four nut members each having a female thread of a ball screw mechanism that engages with the male threads of the four tie bars, a mold clamping electric motor provided on the end housing or bed, and a mold. A worm gear reduction mechanism for mold clamping that can decelerate the rotation of the clamping electric motor and transmit it at low speed and high torque to four tie bars to rotate them in a synchronized state, and a rotational force between the mold clamping electric motor and the tie bars. A clutch that can switch between transmission and cutoff,
A mold opening/closing motor provided on the end housing or bed; and a mold opening/closing drive mechanism capable of transmitting the rotational force of the mold opening/closing motor to four tie bars at high speed and with small torque and driving them to rotate in a synchronized state. A mold clamping device for an injection molding machine.