JP2012166523A - Mold clamping device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold clamping device for an injection molding machine, which has substantially shortened full length.SOLUTION: The mold clamping device is a mold clamping device 10 for the injection molding machine which has a fixed plate 3 fixed to a bed 1 and a movable plate 5 reciprocated on the bed so as to be opposed to the fixed bed 3. The mold clamping device 10 has a connecting rod 13 and a crank arm 15 which constitute a piston-crank mechanism. The connecting rod 13 has one end connected to the movable plate 5 to freely turn and the other end connected to a connection part 17 of the crank arm 15 to freely turn, The crank arm 15 has one end connected to the fixed plate 3 to freely turn and the other end having a rotor 23 rocking along an arc-like stator 21. A linear motor 20 is composed of the rotor 23 and the stator 21.

Description

  The present invention relates to a mold clamping device of an injection molding machine, and more particularly to a mold clamping device using a linear motor.

  The toggle mechanism is widely used as a mold clamping device of an injection molding machine because it has an advantage that a large mold clamping force can be obtained with a simple link mechanism. However, there is a problem that the number of parts is large and there is a problem that three mold plates are required and the total length becomes long. In order to improve these problems, a mold clamping device using a link mechanism other than the toggle mechanism has been proposed. .

  For example, Patent Document 1 includes a crank mechanism that converts rotational motion of a driving shaft into linear motion at an operating point, and a rotor of a direct drive servo motor is directly connected to the driving shaft and a movable platen is connected to the operating point. There has been proposed a direct drive type mold clamping device in an injection molding machine.

  Patent Document 2 proposes a mold clamping device in which both a link mechanism capable of performing a mold opening / closing operation at high speed and a hydraulic cylinder capable of obtaining a high-pressure mold clamping force are provided side by side. The link mechanism used in this mold clamping device has a form similar to a piston / crank mechanism, and one end of the link mechanism is pivotally connected to opposite circular peripheral portions across the rotation center axis of the rotation plate. It has first and second connecting links, the other end of the first connecting link is rotatably connected to a pressure receiving plate fixed to the tie bar, and the other end of the second connecting link reciprocates on the tie bar. It is configured to be rotatably connected to a movable plate.

  On the other hand, for a direct pressure type mold clamping apparatus using a hydraulic cylinder, a mold clamping apparatus in which the hydraulic cylinder portion is replaced with a linear motor has been proposed in order to realize a high-speed mold opening / closing operation. For example, Patent Documents 3 and 4 propose a mold clamping device in which an output shaft of a linear motor is connected to a cross head coupled to a toggle mechanism.

Japanese Unexamined Patent Publication No. 01-280521 JP 2003-136572 A JP 2002-345231 A International Publication WO04 / 078453 A1 Publication

  The mold clamping device proposed in Patent Document 1 not only can perform a mold opening / closing operation at a higher speed than a toggle type mold clamping device, but also has an advantage of having a simple structure. There is a problem that it is difficult to construct a large mold clamping device with high pressure.

  The mold clamping apparatus proposed in Patent Document 2 can constitute a mold clamping apparatus having a high-speed mold opening / closing operation and a high mold clamping pressure, but the problem is that the structure of the mold clamping apparatus is complicated and the entire apparatus becomes large. There is.

  The mold clamping devices proposed in Patent Documents 3 and 4 have a structure in which the structure of the rotation servo motor and ball screw of a normal electric injection machine is replaced with a linear motor. However, the mold clamping device using these toggle mechanisms requires a pressure receiving plate for supporting one end of the toggle mechanism and receiving a reaction force that the toggle mechanism receives from the movable platen (three platen type mold clamping device). There is a problem that the overall length of the fastening device becomes long and the structure becomes complicated.

  An object of the present invention is to provide a mold clamping device that can quickly open and close the mold and shorten the entire length of the mold clamping device in view of the problems associated with the mold clamping device of such an injection molding machine. .

  A mold clamping device according to the present invention is a mold clamping device of an injection molding machine having a fixed plate fixed to a bed and a movable plate that reciprocates on the bed so as to face the fixed plate. The fastening device has a connecting rod and a crank arm that constitute a piston / crank mechanism, and one end of the connecting rod is rotatably coupled to the movable platen, and the other end is rotated at a connecting portion with the crank arm. It is connected freely. The crank arm has a rotor that is rotatably coupled at one end to the fixed plate and swings along the arcuate stator at the other end, and the rotor and the stator constitute a linear motor. It is like that.

  In the above invention, the linear motor is preferably composed of a rotor and a stator configured such that the load is small when the movable platen is moved and the load is large when the mold is clamped. The connecting rod preferably has a length adjusting means.

  According to the mold clamping device of the injection molding machine according to the present invention, the number of parts constituting the mold clamping device can be greatly reduced, and the overall length of the mold clamping device can be shortened.

It is a schematic diagram which shows the side (a) and part (b) of a plane of the mold clamping device which concerns on this invention. It is a schematic diagram which shows the example of the mold clamping apparatus from which the mold thickness adjustment means differs from the example of FIG.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of a mold clamping device of an injection molding machine according to the present invention. As shown in FIG. 1, a mold clamping device 10 of this example is an injection molding machine having a stationary platen 3 fixed to a bed 1 and a movable platen 5 reciprocating on the bed facing the stationary platen 3. And a two-platen type clamping device. The mold clamping device 10 includes a connecting rod 13 and a crank arm 15 constituting a piston / crank mechanism. The connecting rod 13 has one end rotatably connected to the movable platen 5 and the other end connected to the crank arm 15. The crank arm 15 has one end rotatably coupled to the stationary platen 3 and the other end having a rotor 23 that swings along an arcuate stator 21. The rotor 23 and the stator 21 constitute a linear motor 20.

  As shown in FIG. 1B, the connecting rod 13, crank arm 15 and linear motor 20 of the mold clamping device 10 are provided symmetrically with respect to the bed 1. The connecting rod 13 is provided so as to extend from the movable platen 5 to the fixed platen 3, and the stator 21 of the linear motor 20 is provided so as to sandwich an injection cylinder (not shown). Thereby, the overall length of the injection molding machine using the mold clamping device 10 can be shortened.

  In the mold clamping apparatus 10, the fixed platen 3 is fixed to the bed 1. The movable platen 5 can reciprocate on the bed 1. The mold clamping apparatus 10 of this example is not provided with a so-called tie bar, but may be provided with a tie bar. When the tie bar is provided, the movable platen 5 can be smoothly moved by the tie bar, and the parallelism between the solid plate 3 and the movable platen 5 can be improved. In the mold clamping apparatus 10, the tie bar does not receive a mold clamping force, so that the outer diameter can be made smaller than that of a normal injection machine tie bar.

  The crank arm 15 can be rotated 90 ° counterclockwise from the state shown in FIG. 1 (rotation angle 0 °) by the linear motor 20 described below, and can be returned to the rotation angle 0 ° state. The swing of the crank arm 15 causes the movable platen 5 to reciprocate via the connecting rod 13 connected to the connecting portion 17. The movable platen 5 is in the maximum movement position when the rotation angle is 0 °, and is in the minimum movement position (clamping position) when the rotation angle is 90 °. In the example of FIG. 1, the movable range of the linear motor is described as being in the range of 0 to 90 °. However, the movable range may be 90 ° or more. The stroke can be increased.

  The piston / crank mechanism composed of the connecting rod 13 and the crank arm 15 allows the movable platen 5 to reciprocate at a high speed when the mold is opened and closed, and at a high pressure when clamping the mold. Tightening can be done. The connecting rod 13 may be provided with length adjusting means 13a for adjusting the length thereof. The length adjusting means 13a is not particularly limited. For example, when the length adjusting means 13a portion is configured by screw coupling, the screw mounting hole may be a long hole, or the screw hole position may be shifted. The length of the connecting rod 13 may be adjusted. By this length adjusting means 13a, the mold thickness which varies depending on the mold can be adjusted, and the distance between the fixed platen 3 and the movable platen 5 can be maintained at an appropriate dimension.

  The linear motor 20 has a rotor 23 provided at an end of the crank arm 15 and a stator 21 on an arc, and the stator 21 is fixed to the bed 1. Further, in the linear motor 20, a copper wire is wound around an iron core so that the stator 21 becomes an electromagnet, and the rotor 23 swings at a rotation angle of 0 to 90 °. A permanent magnet is used for the rotor 23. However, the rotor 23 may be configured by an electromagnet. The linear motor 20 may be configured such that the rotor 23 swings at a rotation angle of 0 to 180 °.

  Since the linear motor can adjust the magnetic force generated in the coil by adjusting the shape and the number of turns of the coil, the load of the linear motor can be adjusted by the rotation angle. That is, the linear motor 20 can be configured such that the load is small when the movable platen 5 is moved and the load is large when the mold is clamped, and an efficient mold clamping device can be configured. Note that the rotor and the stator may be interchanged, the tip of the crank arm 15 may be a stator, and the portion on the arc may be a rotor.

  In the mold clamping device 10, the tip end portion of the crank arm 15 is held by the linear motor 20. For this reason, the connecting portion 17 is not a free end as in a mold clamping device using a conventional piston / crank mechanism. The movable platen 5 is reciprocated by receiving a load directly from the end of the connecting rod 13. With this configuration, the mold clamping device 10 can be operated at a high pressure and can be configured without a tie bar. Also, the crankshaft 15 and the rotating shaft provided on the stationary platen 3 can fulfill the function of a motor bearing used in a conventional mold clamping device, so the number of parts constituting the mold clamping device 10 is reduced. can do.

  The present mold clamping device 10 has been described above. The mold clamping apparatus according to the present invention is not limited to the mold clamping apparatus having the configuration shown in FIG. For example, a mold clamping device provided with a mold thickness adjusting device 7 having the configuration shown in FIG. 2 may be used as a mold thickness adjusting means for adjusting a different mold thickness depending on the mold.

1 bed
3 Fixed platen
5 Movable platen
7 Mold thickness adjuster
10 Clamping device
13 Connecting rod
15 Crank arm
17 Connecting part
20 linear motor
21 Stator
23 Rotor

Claims (3)

A mold clamping device of an injection molding machine having a fixed plate fixed to a bed and a movable plate that reciprocates on the bed facing the fixed plate,
The mold clamping device is:
It has a connecting rod and a crank arm that make up the piston / crank mechanism,
One end of the connecting rod is rotatably coupled to the movable platen, and the other end is pivotally coupled at a connecting portion with the crank arm,
The crank arm has a rotor that is pivotally connected at one end to the fixed plate and swings along an arc-shaped stator at the other end, and the rotor and the stator constitute a linear motor. The mold clamping device.   2. The mold clamping apparatus according to claim 1, wherein the linear motor includes a rotor and a stator configured such that a load is small when the movable platen is moved and a load is large when the mold is clamped.   The mold clamping apparatus according to claim 1 or 2, wherein the connecting rod has a length adjusting means.

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