JP2866314B2 - Mold clamping device - Google Patents

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 heated and melted in a heating cylinder is injected at a high pressure, filled in a mold cavity, and 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 to move the mold toward and away from the mold. It has become. On the other hand, the injection device includes a heating cylinder for heating and melting the resin supplied from the hopper, and an injection nozzle for injecting the melted resin, and a screw is disposed in the heating cylinder so as to be able to move forward and backward. The resin can be injected by moving the screw forward, and can be measured by moving the screw backward.

An injection molding machine using a servomotor for moving the mold clamping device forward and backward has been provided. 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. In addition, the upper side of the center line in FIG. 2 indicates the mold closed state of the mold clamping device, and the lower side of the center line indicates the mold open state of the mold clamping device.

In FIG. 1, reference numeral 11 denotes a movable platen to which a movable mold (not shown) is attached, and 12 denotes a toggle support. A tie bar 13 connects the toggle support 12 and a fixed platen (not shown). The movable platen 11 slides, closes the mold,
Perform mold clamping and mold opening. For this purpose, a toggle mechanism 15 is provided between the toggle support 12 and the movable platen 11, and the toggle mechanism 15 is operated by a servo motor 16 for mold clamping drive so as to move the movable platen 11 forward and backward. Has become.

The toggle mechanism 15 includes a toggle lever 1 supported swingably with respect to 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 that are swingably supported with respect to the toggle lever 18 and the movable platen 11, and the toggle lever 18 and the crosshead 21 are connected to each other. It comprises a toggle lever 22 which is connected and is swingably supported with respect to the toggle lever 18 and 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 crosshead 21 are screwed together. ). Then, by rotating the ball screw shaft 25, the crosshead 21 is moved forward and backward,
1 at the retreat limit position, the toggle mechanism 15 is positioned below the center line in FIG. 2 to form a mold open state of the mold clamping device. Can be formed above the center line to form the mold-closed state of the mold-clamping device.

A belt transmission mechanism 26 is provided between the servo motor 16 and the ball screw shaft 25.
The belt transmission mechanism 26 includes a pulley 27 disposed on the output shaft of the servomotor 16, a pulley 28 disposed at the tip of the ball screw shaft 25, and a timing belt stretched between the pulleys 27 and 28. 29. Therefore, when the servo motor 16 is driven, the servo motor 1
The rotation of the ball screw shaft 2 through the belt transmission mechanism 26
5 is transmitted. Then, the rotary motion is converted into a linear motion by the ball screw shaft 25 and the nut, the toggle mechanism 15 is operated, and the mold is closed, clamped and opened. An ejector mechanism 31 for ejecting an ejector pin (not shown) is provided on the toggle mechanism 15 side of the movable platen 11 when the mold is released after the mold is opened.

FIG. 4 is a view showing an ejector device mounting portion of another conventional mold clamping device. In the figure, 32 is an ejector servo motor, 33 and 34 are ejector ball screw shafts, 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 and 34 are divided into two, and the center portion is opened so that the ball screw shaft 25 for mold clamping and the ball screw shafts 33 and 34 for ejectors do not interfere with each other when the mold is opened. ing. In the drawing, 11 is a movable platen, and 13 is a tie bar.

FIG. 5 is a front view of still another conventional mold clamping device. Note that the upper side of the center line in FIG. 5 indicates the mold closed state of the mold clamping device, and the lower side of the center line indicates the mold open state of the mold clamping device. In the drawing, reference numeral 11 denotes a movable platen to which a movable mold (not shown) is attached, and 12 denotes a toggle support. The tie bar 1 connects the toggle support 12 and a fixed platen (not shown).
The movable platen 11 slides along the tie bar 13 to close, close, and open the mold. For this purpose, a toggle mechanism 15 is provided between the toggle support 12 and the movable platen 11, and the toggle mechanism 15 is operated by a servo motor 16 (Fig. 3) for mold clamping drive, and the movable platen 11 is moved. It is designed to retreat.

The toggle mechanism 15 includes a toggle lever 1 swingably supported by the toggle support 12.
8, an arm 19 connected to the toggle lever 18 and the movable platen 11 so as to be swingable with respect to 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 include a toggle lever 18 and a toggle lever 22 that is swingably supported by the crosshead 21.

In the center of the toggle support 12, a nut 40 is rotatably disposed 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 moved forward and backward, and at the retreat limit position of the crosshead 21, the toggle mechanism 15 is placed below the center line in FIG. The mold opening state is formed, and the toggle mechanism 15 can be set to the state shown above the center line in FIG. 5 at the forward limit position of the crosshead 21 to form the mold closing state of the mold clamping device.

A pulley 28 is provided 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 rotational motion is converted into a linear motion by the ball screw shaft 25 and the nut 40, the toggle mechanism 15 is operated, and the mold is closed, clamped and opened. In this case, since the ball screw shaft 25 is retracted in the mold open state, the ball screw shaft 25 does not interfere with the toggle mechanism 15.

[0014]

However, in the conventional mold clamping device, the timing belts 29, 3
8 is relatively low in durability and wears while the mold clamping device is repeatedly operated, so that abrasion powder is generated and the surroundings are soiled. Therefore, maintenance and management become difficult.

Further, an eccentric load is applied to each of the pulleys 28, 36 and 37 by the tension of each of the timing belts 29 and 38, and the efficiency of the ball screw shaft 25 is reduced. And since the durability of the timing belts 29 and 38 is low,
Spread occurs and the control accuracy of the mold clamping device is lowered, or breakage occurs, and it is necessary to replace the mold in a relatively short time. Therefore, it is conceivable to increase the durability by changing the material of each of the timing belts 29 and 38, but there is 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 retreats as the crosshead 21 retreats.
Since the ball screw shaft 25 remains as it is, it is necessary to form a structure such that the ball screw shaft 25 does not interfere with the toggle lever 18, the arm 19, the toggle lever 22, and the like. Further, since the servo motor 16 protrudes from the back surface of the toggle support 12, the dimension in the depth direction of the mold clamping device also increases.

In the case of a two-axis type ejector device having two ejector ball screw shafts 33 and 34 as shown in FIG. 4, interference between the ball screw shafts 33 and 34 and the toggle mechanism is prevented. Although it can be prevented, the number of parts increases, the cost increases, and the replacement of the timing belt 38 becomes difficult. Further, since the servo motor 32 protrudes from the rear surface of the movable platen 11, the dimension in the depth direction of the mold clamping device also increases.

In the case of the mold clamping device shown in FIG. 5, when the mold is opened, the ball screw shaft 25 is retracted and projects rearward, so that the axial dimension of the mold clamping device is increased. 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 of an injection molding machine that can reduce the cost and reduce the dimension of the mold clamping device in the depth direction.

[0019]

For this purpose, in the mold clamping device of the present invention, a movable platen and a rotation are generated.
A driving device that moves the movable platen forward and backward based on the rotation, a hollow output shaft that is mounted radially inward of the driving device, and outputs a rotation generated by the driving device, and a rotational motion of the output shaft And a nut mounted on the output shaft and screwed with the ball screw shaft, and an encoder for directly detecting the rotation generated by the driving device. And

A part of the ball screw shaft is housed in the output shaft.

[0021]

According to the present invention, as described above, in the mold clamping device, a movable platen, a drive device for generating rotation and moving the movable platen forward and backward based on the rotation, And a hollow output shaft for outputting the rotation generated by the driving device, and a ball screw shaft, and a hollow output shaft for converting the rotational motion of the output shaft into a linear motion. A nut screwed onto the ball screw shaft; and an encoder for directly detecting the rotation generated by the driving device. Then, a part of the ball screw shaft is housed in the output shaft.

In this case, when the rotation generated by the driving device is output to a nut via an output shaft, the rotational motion is converted into a linear motion by the nut and the ball screw shaft, and the movable platen is moved forward and backward. During this time, the encoder directly detects the rotation.

Since a part of the ball screw shaft is housed in the output shaft, the ball screw shaft moves in the output shaft when the mold is opened.

[0024]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 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. Note that the upper side of the center line in FIG. 1 indicates the mold closed state of the mold clamping apparatus, and the lower side of the center line indicates the mold open state of the mold clamping apparatus.

In the drawing, reference numeral 11 denotes a movable platen to which a movable mold (not shown) is attached, and 12 denotes a toggle support. A tie bar 13 connects the toggle support 12 and a fixed platen (not shown). The movable platen 11 slides to close, close, and open the mold. To this end, a toggle mechanism 15 is provided between the toggle support 12 and the movable platen 11, and the toggle mechanism 15 is operated by a driving device 50 to move the movable platen 11 forward and backward.

The toggle mechanism 15 includes a toggle lever 1 swingably supported by the toggle support 12.
8, a cross head 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 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 that is supported to be swingable with respect to the toggle lever 18 and the crosshead 21.

At the center of the toggle support 12, a driving device 50 is provided so as to protrude rearward. The drive device 50 is directly toggle-supported by bolts 51.
Fixed to 2. The driving device 50 is rotatably supported by a driving device case 52, a servomotor 53 disposed in the driving device case 52, and the driving device case 52, and outputs the rotation of the servomotor 53. It consists of a hollow rotating sleeve 54 as the output shaft.

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

Then, a ball screw nut 59 is fixed to the inner periphery of the large diameter portion 54a by a bolt 60, and a rotor core 53b is fixed to the outer periphery of the small diameter portion 54b by fitting. Further, the ball screw shaft 25 extends rearward from the crosshead 21,
The ball screw nut 5 extends through the toggle support 12.
9 is screwed. Then, by driving the servo motor 53 to rotate the ball screw nut 59, the ball screw shaft 25 is moved forward and backward, and the toggle mechanism 15 is moved below the center line in FIG. In the state shown in FIG. 1, a mold open state of the mold clamping device is formed, and at the forward end position of the ball screw shaft 25, the toggle mechanism 15 is placed above the center line in FIG. Can be formed.

In this case, 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 retreat limit position. No need. Further, since the timing belt is not used, abrasion powder of the timing belt is not generated and the surroundings are not stained, so that maintenance and management can be facilitated. Furthermore, since the servo motor does not overhang the side surface of the toggle support 12,
The dimension in the depth direction of the mold clamping device 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. In the mold open state, the ball screw shaft 25 is retracted, so that the ball screw shaft 25 and the toggle mechanism 15
And do not interfere. Therefore, the conventional hydraulic toggle mechanism can be replaced with an electric toggle mechanism as it is. Furthermore, since the ball screw shaft 25 is retracted in the mold open state, there is no interference between the ejector device (not shown) and the toggle mechanism 15. Therefore, the ejector device does not need to be a two-axis type using a timing belt, so that the number of parts is 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 rotational motion is converted into a linear motion by the ball screw nut 59 and the ball screw shaft 25, and the toggle mechanism 15 is operated. The mold is closed, closed and opened. An encoder 61 is provided 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
As the third, any of an induction type, a synchronous type and the like can be used. It should be noted that the present invention is not limited to the above-described embodiments, but can be variously modified based on the gist of the present invention, and they are not excluded from the scope of the present invention.

[0034]

As described above in detail, according to the present invention, in a mold clamping device, a movable platen, a driving device for generating rotation and moving the movable platen forward and backward based on the rotation, A hollow output shaft mounted radially inward of the driving device and outputting the rotation generated by the driving device, and a ball screw shaft disposed to convert the rotational motion of the output shaft into a linear motion; And a nut attached to the output shaft and screwed with a ball screw shaft,
An encoder for directly detecting the rotation generated by the driving device. Then, a part of the ball screw shaft is housed in the output shaft.

In this case, when the rotation generated by the driving device is output to a nut via an output shaft, the rotational motion is converted into a linear motion by the nut and the ball screw shaft, and the movable platen is moved forward and backward. During this time, the encoder directly detects the rotation, so that the detection accuracy of the rotation speed can be increased.

Since a part of the ball screw shaft is housed in the output shaft, the axial dimension of the mold clamping device can be reduced. Also, the rotation generated by the drive is transmitted directly to the nut, eliminating the need for a timing belt. Therefore, the timing belt does not generate abrasion powder and contaminate the surroundings, thereby facilitating maintenance and management. Further, since the driving device does not protrude from the side surface of the mold clamping device, the dimension in the depth direction of the mold clamping device can be reduced.

Since no eccentric load is applied to the nut, the efficiency of the ball screw shaft can be increased.

[Brief description of the 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 a 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)

(57) [Claims] 1. A (a) and allowed dynamic platen, to generate a rotating (b), the movable plug on the basis of the rotation
A driving device for advancing and retracting the numeric mounted radially inward of (c) the driving device, the driving instrumentation
A hollow output shaft for outputting the rotation generated by the device, and (d) for converting the rotational motion of the output shaft into a linear motion.
And mounted on the ball screw shaft and the output shaft.
A nut which is screwed a ball Lumpur screw shaft is, (e) which has an encoder for detecting the rotation generated by the drive unit directly, (f) a portion of the ball screw shaft is the A mold clamping device which is housed in an output shaft.