JPH08174612A - Locking apparatus - Google Patents

Abstract

PURPOSE: To decrease the dimension in the depth direction of a locking apparatus. CONSTITUTION: A toggle support 12, a movable platen 11, a toggle mechanism 15, a ball screw shaft 25 the apex of which is fixed to the toggle mechanism 15 and the rear end of which is extended backward, a servo motor arranged on the toggle support 12, a ball screw nut 59 fixed on the output shaft of the servo motor and an encoder for directly detecting the rotation of the output shaft are provided. In this case, when the servo motor is driven and the ball screw nut 59 is rotated through the output shaft, the ball screw shaft 25 screwed with the ball screw nut 59 is advanced or retreated and the movable platen 11 is advanced or retreated. During this time, as the encoder directly detects the rotation of the output shaft, accuracy of detection of the number of rotation can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold clamping device.

[0002]

2. Description of the Related Art Conventionally, in an injection molding machine, a resin which is heated and melted in a heating cylinder is injected at a high pressure, filled in a cavity of a mold, and then cooled and solidified in the cavity. Then, the mold is opened and the molded product is taken out.

The injection molding machine has a mold clamping device and an injection device, and the mold clamping device includes a fixed platen and a movable platen, and a mold clamping cylinder moves the movable platen forward and backward so as to contact and separate the molds. It has become. On the other hand, the injection device includes a heating cylinder that heats and melts the resin supplied from the hopper, and an injection nozzle that injects the melted resin, and a screw is arranged in the heating cylinder so that the screw can advance and retract. The resin can be injected by moving the screw forward, and the resin can be measured by moving the screw backward.

By the way, there has been provided an injection molding machine using a servomotor for moving the mold clamping device forward and backward. FIG. 2 is a front view of a conventional mold clamping device, and FIG. 3 is a side view of the conventional mold clamping device. The upper side of the center line in FIG. 2 shows the mold closed state of the mold clamping device, and the lower side of the center line shows the mold opened state of the mold clamping device.

In the figure, 11 is a movable platen to which a movable mold (not shown) is attached, 12 is a toggle support, and a tie bar 13 connects the toggle support 12 and a fixed platen (not shown), and along the tie bar 13. The movable platen 11 slides to close the mold,
Perform mold clamping and mold opening. To this end, a toggle mechanism 15 is arranged between the toggle support 12 and the movable platen 11, and the toggle mechanism 15 is operated by a servomotor 16 for driving the mold clamping so that the movable platen 11 is moved back and forth. Has become.

The toggle mechanism 15 is a toggle lever 1 which is swingably supported by the toggle support 12.
8, the toggle lever 18 and the movable platen 11 are connected to each other, and the arm 19 and the crosshead 21 swingably supported by the toggle lever 18 and the movable platen 11 and the toggle lever 18 and the crosshead 21 are connected to each other. The toggle lever 18 is connected to the toggle lever 18 and is swingably supported by the crosshead 21.

At the center of the toggle support 12, a ball screw shaft 25 is rotatably supported by a bearing 24, and the ball screw shaft 25 and a nut formed on the cross head 21 are screwed together. ) Can be made. Then, by rotating the ball screw shaft 25, the crosshead 21 is moved back and forth,
2, the toggle mechanism 15 is set below the center line in FIG. 2 to form the mold opening state of the mold clamping device, and the crosshead 21 is moved to the forward limit position. The mold closed state of the mold clamping device can be formed in the state shown above the center line in FIG.

A belt transmission mechanism 26 is arranged between the servo motor 16 and the ball screw shaft 25.
The belt transmission mechanism 26 includes a pulley 27 arranged on the output shaft of the servomotor 16, a pulley 28 arranged at the tip of the ball screw shaft 25, and a timing belt stretched between the pulleys 27, 28. It consists of 29. Therefore, when the servo motor 16 is driven, the servo motor 1
Rotation of the ball screw shaft 2 through the belt transmission mechanism 26.
5 is transmitted. Then, the ball screw shaft 25 and the nut convert the rotational motion into a linear motion, operate the toggle mechanism 15, and perform mold closing, mold clamping, and mold opening. On the toggle mechanism 15 side of the movable platen 11, an ejector mechanism 31 for ejecting an ejector pin (not shown) at the time of mold release after mold opening is provided.

FIG. 4 is a view showing an ejector device mounting portion in another conventional mold clamping device. In the figure, 32 is a servomotor for ejector, 33 and 34 are ball screw shafts for ejector, 35 to 37 are pulleys, 38 is a timing belt stretched between the pulleys 35 to 37, 39 is an ejector plate, 41 Is a guide bar. In this case, the ball screw shafts 33, 34 are divided into two and the central portion is opened so that the ball screw shaft 25 for mold clamping and the ball screw shafts 33, 34 for ejector do not interfere with each other when the mold is opened. ing. In the figure, 11 is a movable platen and 13 is a tie bar.

FIG. 5 is a front view of still another conventional mold clamping device. The upper side of the center line in FIG. 5 shows the mold closed state of the mold clamping device, and the lower side of the center line shows the mold opened state of the mold clamping device. In the figure, 11 is a movable platen to which a movable mold (not shown) is attached, 12 is a toggle support, and the toggle support 12 and a fixed platen (not shown) are connected to a tie bar 1
3, the movable platen 11 slides along the tie bar 13 to close the mold, and perform mold clamping and mold opening. For that purpose, a toggle mechanism 15 is arranged between the toggle support 12 and the movable platen 11, and the toggle mechanism 15 is operated by a servomotor 16 (FIG. 3) for driving the mold clamping to move the movable platen 11 to the movable platen 11. It is designed to move forward and backward.

The toggle mechanism 15 is a toggle lever 1 which is swingably supported by the toggle support 12.
8, an arm 19 that connects the toggle lever 18 and the movable platen 11 and is swingably supported by the toggle lever 18 and the movable platen 11, a crosshead 21 fixed to a ball screw shaft 25, and the toggle. Lever 1
8 and the crosshead 21 are connected to each other, and they are composed of a toggle lever 18 and a toggle lever 22 swingably supported by the crosshead 21.

A nut 40 is rotatably disposed in the center of the toggle support 12 by a bearing 24, and the nut 40 and the ball screw shaft 25 are screwed together. Then, by rotating the ball screw shaft 25, the crosshead 21 is advanced and retracted, and at the retracted limit position of the crosshead 21, the toggle mechanism 15 is brought to a state shown below the center line in FIG. The mold open state is formed, and at the forward limit position of the crosshead 21, the toggle mechanism 15 can be set to the state shown above the center line in FIG. 5 to form the mold closed state of the mold clamping device.

A pulley 28 is arranged on the nut 40, and the rotation of a servo motor (not shown) is transmitted to the ball screw shaft 25 via the pulley 28. Then, the ball screw shaft 25 and the nut 40 convert the rotational motion into a linear motion, operate the toggle mechanism 15, and perform mold closing, mold clamping and mold opening. In this case, since the ball screw shaft 25 is retracted in the mold open state, the ball screw shaft 25 and the toggle mechanism 15 do not interfere with each other.

[0014]

However, in the above-mentioned conventional mold clamping device, the timing belts 29, 3 are not provided.
The durability of No. 8 is relatively low, and wears during repeated operation of the mold clamping device, so that abrasion powder is generated and the surroundings are soiled. Therefore, maintenance / management becomes difficult.

Further, the tension of each timing belt 29, 38 applies an eccentric load to each pulley 28, 36, 37, which reduces the efficiency of the ball screw shaft 25. Since the timing belts 29 and 38 have low durability,
Therefore, it is necessary to replace the mold clamping device in a relatively short time because the mold is stretched to lower the control accuracy of the mold clamping device or to break. Therefore, it is conceivable to change the material of the timing belts 29 and 38 to improve the durability, but there arises a problem that noise is generated during high speed operation.

In the case of the mold clamping device shown in FIGS. 2 and 3,
In the mold open state, the movable platen 11 retracts as the crosshead 21 retracts. At this time,
Since the ball screw shaft 25 remains as it is, it is necessary to form a structure in which the ball screw shaft 25 does not interfere with the toggle lever 18, the arm 19, the toggle lever 22 and the like. Furthermore, since the servo motor 16 projects to the back surface of the toggle support 12, the dimension of the mold clamping device in the depth direction also increases.

In the case of the two-axis type ejector device having the two ball screw shafts 33 and 34 for ejectors as shown in FIG. 4, the ball screw shafts 33 and 34 interfere with the toggle mechanism. Although it can be prevented, not only the number of parts increases, the cost increases, but also the replacement of the timing belt 38 becomes difficult. Further, since the servo motor 32 projects to the back surface of the movable platen 11, the dimension of the mold clamping device in the depth direction also increases.

Further, in the case of the mold clamping device shown in FIG. 5, in the mold open state, the ball screw shaft 25 is retracted and protrudes rearward, so that the axial dimension of the mold clamping device becomes large. The present invention solves the problems of the conventional mold clamping device, facilitates maintenance and management, prevents the efficiency of the mold clamping device from decreasing, and reduces the number of parts. An object of the present invention is to provide a mold clamping device for an injection molding machine, which can reduce the cost and can reduce the dimension of the mold clamping device in the depth direction.

[0019]

Therefore, in the mold clamping device of the present invention, a toggle support, a movable platen, a toggle mechanism arranged between the toggle support and the movable platen, and the tip end are Fixed on a toggle mechanism,
A ball screw shaft having a rear end penetrating the toggle support and extending rearward, a servo motor arranged on the toggle support, a hollow output shaft for outputting rotation of the servo motor, and fixed to the output shaft. , A nut screwed with the ball screw shaft, and an encoder for directly detecting the rotation of the output shaft.

The ball screw shaft is housed in the output shaft at the retracted limit position.

[0021]

According to the present invention, as described above, in the mold clamping device, the toggle support, the movable platen, the toggle mechanism disposed between the toggle support and the movable platen, and the tip end of the toggle mechanism. A ball screw shaft having a rear end that extends rearward through the toggle support, a servo motor disposed on the toggle support, a hollow output shaft that outputs rotation of the servo motor, and the output. It has a nut fixed to a shaft and screwed with the ball screw shaft, and an encoder for directly detecting the rotation of the output shaft.

In this case, when the servomotor is driven and the nut is rotated through the output shaft, the ball screw shaft screwed with the nut is advanced and retracted. Since the tip of the ball screw shaft is fixed to the toggle mechanism, the toggle mechanism is actuated as the ball screw shaft advances and retracts, and the movable platen advances and retracts. During this time, the encoder directly detects the rotation of the output shaft.

The ball screw shaft is housed in the output shaft at the retracted limit position. Therefore, when the mold is opened, the ball screw shaft moves to the backward limit position,
At this time, the ball screw shaft is housed in the hollow output shaft.

[0024]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 is a front view of a mold clamping device according to an embodiment of the present invention, FIG. 6 is a side view of the mold clamping device according to the embodiment of the present invention, and FIG. 7 is a detailed view of a servomotor according to the embodiment of the present invention. The upper side of the center line in FIG. 1 shows the mold closed state of the mold clamping device, and the lower side of the center line shows the mold opened state of the mold clamping device.

In the figure, 11 is a movable platen to which a movable mold (not shown) is attached, 12 is a toggle support, and a tie bar 13 connects the toggle support 12 and a fixed platen (not shown). The movable platen 11 slides to close the mold, and to perform mold clamping and mold opening. Therefore, a toggle mechanism 15 is arranged between the toggle support 12 and the movable platen 11, and the toggle mechanism 15 is operated by a drive device 50 to move the movable platen 11 forward and backward.

The toggle mechanism 15 is a toggle lever 1 which is swingably supported by the toggle support 12.
8. An arm 19 that connects the toggle lever 18 and the movable platen 11 and is swingably supported by the toggle lever 18 and the movable platen 11, and a crosshead fixed to a ball screw shaft 25 via a nut 21a. 21 and a toggle lever 22 that connects the toggle lever 18 and the crosshead 21 and is swingably supported by the toggle lever 18 and the crosshead 21.

A driving device 50 is provided at the center of the toggle support 12 so as to project rearward. The drive device 50 is a toggle support 1 directly by means of bolts 51.
Fixed to 2. The drive device 50 is rotatably supported by the drive device case 52, the servo motor 53 disposed in the drive device case 52, and the drive device case 52, and outputs the rotation of the servo motor 53. It consists of a hollow rotating sleeve 54 as an output shaft.

The drive unit case 52 has a side wall 52a arranged in contact with the toggle support 12, a side wall 52b arranged opposite to the side wall 52a, and a cylinder connecting the side walls 52a, 52b. The cover 52c.
Further, the servo motor 53 is connected to the drive unit case 52.
Stator core 53 a fixed to the stator core 5 and the stator core 5
The rotor core 53b is rotatably arranged on the inner peripheral side of 3a. Further, the rotating sleeve 54 includes a large diameter portion 54a and a small diameter portion 54b formed rearward from the large diameter portion 54a, and the large diameter portion 54a is rotatably supported by the bearing 56 with respect to the side wall 52a. The small diameter portion 54b is rotatably supported by the bearing 57 with respect to the side wall 52b.

A ball screw nut 59 is fixed to the inner circumference of the large diameter portion 54a by a bolt 60, and a rotor core 53b is fixed to the outer circumference of the small diameter portion 54b by fitting. The ball screw shaft 25 extends rearward from the crosshead 21,
The ball screw nut 5 passing through the toggle support 12
Screwed with 9. Then, the servomotor 53 is driven to rotate the ball screw nut 59, thereby advancing and retracting the ball screw shaft 25. When the ball screw shaft 25 is retracted, the toggle mechanism 15 is moved downward from the center line in FIG. The mold opening state of the mold clamping device is formed in the state shown in FIG. 2, and the toggle mechanism 15 is set to the state shown above the center line in FIG. Can be formed.

In this case, since the ball screw shaft 25 advances and retreats in the small diameter portion 54b of the rotary sleeve 54 and is accommodated in the small diameter portion 54b even at the retracted limit position, the axial dimension of the mold clamping device is made too large. No need. Further, since the timing belt is not used, abrasion powder of the timing belt is not generated and the surroundings are not polluted, and maintenance and management can be facilitated. Furthermore, since the servo motor does not project to the side of the toggle support 12,
The dimension of the mold clamping device in the depth direction can be reduced.

Since no eccentric load is applied to the ball screw nut 59, the efficiency of the mold clamping device can be increased. Further, since the ball screw shaft 25 is retracted in the mold open state, the ball screw shaft 25 and the toggle mechanism 15
And will not interfere. Therefore, it is possible to replace the conventional hydraulic toggle mechanism with the electric toggle mechanism as it is. Further, since the ball screw shaft 25 is retracted in the mold open state, the ejector device (not shown) and the toggle mechanism 15 do not interfere with each other. Therefore, the ejector device does not need to be a biaxial type using a timing belt, so that the number of parts can be reduced and the cost can be reduced.

As described above, when the servo motor 53 is driven to rotate the ball screw nut 59, the ball screw nut 59 and the ball screw shaft 25 convert the rotational movement into a linear movement, and the toggle mechanism 15 is operated. , Mold closing, mold closing and mold opening are performed. An encoder 61 is arranged at the rear end of the side wall 52b so that the rotation of the small diameter portion 54b or the ball screw nut 59 can be directly detected. Therefore, the detection accuracy of the rotation speed can be increased.

In this embodiment, the servo motor 5
Any of inductive type, synchronous type, etc. can be used as 3. It should be noted that the present invention is not limited to the above embodiments, and various modifications can be made based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0034]

As described in detail above, according to the present invention, in the mold clamping device, the toggle support, the movable platen, and the toggle mechanism arranged between the toggle support and the movable platen, A ball screw shaft having a front end fixed to the toggle mechanism and a rear end extending rearward through the toggle support, a servo motor arranged on the toggle support, and a hollow output for outputting rotation of the servo motor. It has a shaft, a nut fixed to the output shaft and screwed with the ball screw shaft, and an encoder for directly detecting the rotation of the output shaft.

In this case, when the servomotor is driven and the nut is rotated through the output shaft, the ball screw shaft screwed with the nut is advanced and retracted. As the ball screw shaft advances and retracts, the toggle mechanism is actuated and the movable platen advances and retracts. During this time, since the encoder directly detects the rotation of the output shaft, it is possible to improve the detection accuracy of the rotation speed.

The ball screw shaft is housed in the output shaft at the retracted limit position. Therefore, it is not necessary to increase the axial dimension of the mold clamping device so much. Further, since the timing belt is not used, abrasion powder of the timing belt is not generated and the surroundings are not polluted, and maintenance and management can be facilitated. Further, since the servo motor does not project to the side surface of the toggle support, the dimension of the mold clamping device in the depth direction can be reduced.

Since the eccentric load is not applied to the nut, the efficiency of the ball screw shaft can be increased. Further, since the ball screw shaft is retracted in the mold open state, the ball screw shaft does not interfere with the toggle mechanism. Therefore, it is possible to replace the conventional hydraulic toggle mechanism with the electric toggle mechanism as it is. Further, since the ball screw shaft is retracted in the mold open state, the ejector device and the toggle mechanism do not interfere with each other. Therefore, the ejector device does not need to be a biaxial type using a timing belt, so that the number of parts can be reduced and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a front view of a mold clamping device according to an embodiment of the present invention.

FIG. 2 is a front view of a conventional mold clamping device.

FIG. 3 is a side view of a conventional mold clamping device.

FIG. 4 is a view showing an ejector device mounting portion in another conventional mold clamping device.

FIG. 5 is a front view of still another conventional mold clamping device.

FIG. 6 is a side view of the mold clamping device according to the embodiment of the present invention.

FIG. 7 is a detailed view of the servo motor according to the embodiment of the present invention.

[Explanation of symbols]

 11 Movable Platen 12 Toggle Support 15 Toggle Mechanism 25 Ball Screw Shaft 53 Servo Motor 54 Rotating Sleeve 59 Ball Screw Nut 61 Encoder

Claims (1)

[Claims] 1. (a) a toggle support, (b) a movable platen, (c) a toggle mechanism disposed between the toggle support and the movable platen, and (d) a tip fixed to the toggle mechanism. A ball screw shaft having a rear end that extends rearward through the toggle support; (e) a servomotor disposed on the toggle support; and (f) a hollow output shaft that outputs rotation of the servomotor. And (g) a nut fixed to the output shaft and screwed into the ball screw shaft, and (h) an encoder that directly detects rotation of the output shaft, and (i) the ball screw shaft. A mold clamping device, wherein the mold clamping device is housed in the output shaft at a retracted limit position.