JP2950406B2 - Ejector device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ejector device.

[0002]

2. Description of the Related Art Conventionally, in an injection molding machine, a resin heated and melted in a heating cylinder is filled at a high pressure into a cavity space of a mold apparatus, and cooled and solidified in the cavity space. Thus, a molded article is obtained. The mold device is composed of a fixed mold and a movable mold. The movable mold is moved forward and backward by a toggle mechanism, and is brought into contact with and separated from the fixed mold to perform mold closing, mold clamping, and mold opening. You can do it. Then, in opening the mold, the mold clamping device is retracted with the molded product remaining in the movable mold, and subsequently, the ejector pin is advanced by the ejector device, the molded product is ejected, and the mold is released. It has become.

[0003] To this end, the ejector pins are disposed with the front end facing the cavity space, and the rear end is fixed to an ejector plate. An ejector pin feeder is connected to a rear end of the ejector plate via an ejector rod. Then, when the ejector pin feeder is operated and the ejector plate is advanced through the ejector rod, the ejector pin fixed to the ejector plate is advanced.

By the way, in an electric injection molding machine,
Usually, the ejector pin feeder is operated by an electric motor. FIG. 2 is a front view of a conventional single-shaft ejector device, and FIG. 3 is a side view of a conventional single-shaft ejector device. In the figure, reference numeral 11 denotes a movable platen, and a movable mold (not shown) is attached to a front end (right end in FIG. 2) of the movable platen 11. The movable platen 11 is advanced and retracted by a toggle mechanism 14 along a tie bar 12 provided between a fixed platen (not shown) and a toggle support.

The rear end of the movable platen 11 (FIG. 2)
(The left end of the figure), an ejector pin feeder 16 is provided. In the ejector pin feeder 16,
A front end of a guide post 18 is fixed to the movable platen 11, and a support 19 is fixed to a rear end of the guide post 18. The support 19 rotatably supports the nut 22 via a bearing 20.

[0006] The nut 22 is screwed with the ball screw shaft 24 on the inner periphery thereof.
The crosshead 25 is fixed to the front end of the crosshead 4, and the ejector rod 27 is fixed to the front end of the crosshead 25. Therefore, by rotating the nut 22, the ball screw shaft 24 can be advanced and retracted in the direction of arrow A, and the ejector rod 27 can be advanced and retracted in the same direction.

The ejector pin feeder 16 is operated by a servomotor 28, and a belt transmission mechanism 31 is disposed between the servomotor 28 and the nut 22. The belt transmission mechanism 31 includes a pulley 32 disposed on an output shaft of the servomotor 28, a pulley 33 disposed on a rear end of the nut 22, and a timing belt stretched between the pulleys 32, 33. 34.

Therefore, when the servo motor 28 is driven, the rotation of the servo motor 28 is transmitted to the nut 22 via the belt transmission mechanism 31. And the nut 22
The rotational motion is converted into a linear motion by the ball screw shaft 24 and the ejector pin (not shown) is moved forward and backward.
Next, a two-axis ejector device will be described.

FIG. 4 is a front view of a conventional two-axis type ejector device, and FIG. 5 is a side view of a conventional two-axis type ejector device. In the figure, reference numeral 11 denotes a movable platen, and a movable mold (not shown) is attached to a front end (right end in FIG. 4) of the movable platen 11. The movable platen 11
By the toggle mechanism 14, it is advanced and retracted along the tie bar 12 provided between the fixed platen (not shown) and the toggle support.

The rear end of the movable platen 11 (FIG. 4)
(The left end of the figure), an ejector pin feeder 16 is provided. In the ejector pin feeder 16,
The front end of the guide post 18 is fixed to the movable platen 11, and the crosshead 41 is fixed to the rear end of the guide post 18. Then, a nut 42 is attached to the crosshead 41.
Is fixed.

Further, the nut 42 is screwed on an inner periphery with a ball screw shaft 43, and the ball screw shaft 43 is
The front end is rotatably supported by the movable platen 11 by a bearing (not shown). The ejector rod 27 is fixed to the front end of the cross head 41. Therefore, by rotating the ball screw shaft 43, the crosshead 41 can be advanced and retracted, and the ejector rod 27 can be similarly advanced and retracted.

The ejector pin feeder 16 is operated by a servomotor 28, and a belt transmission mechanism 46 is disposed between the servomotor 28 and the ball screw shaft 43. . The belt transmission mechanism 46 is extended between the pulleys 32 disposed on the output shaft of the servomotor 28, a plurality of pulleys 33 disposed on the front end of the ball screw shaft 43, and the respective pulleys 32, 33. Timing belt 34.

Accordingly, when the servo motor 28 is driven, the rotation of the servo motor 28 is transmitted to the ball screw shaft 43 via the belt transmission mechanism 46. Then, the rotational motion is converted into a linear motion by the ball screw shaft 43 and the nut 42, and an ejector pin (not shown) is moved forward and backward.

[0014]

However, in the above-mentioned conventional ejector device, not only does the timing belt 34 need to be strongly stretched in order to completely protrude the molded product from the movable mold and release the molded product. Since the ejector pin needs to be repeatedly advanced and retracted, it is placed under severe conditions, and the durability of the ejector device is reduced.

That is, since the timing belt 34 needs to be strongly stretched, the ball screw shafts 24 (FIG. 2), 43
Of the ball screw shafts 24 and 43, the efficiency of the ball screw shafts 24 and 43 is reduced, and not only the load on the servomotor 28 is increased but also the life of the ball screw shafts 24 and 43 is shortened. In addition, since the timing belt 34 is stretched and the control accuracy of the ejector device is reduced, or the timing belt 34 is broken or worn, the timing belt 34 needs to be replaced in a relatively short time.

Furthermore, abrasion of the timing belt 34 generates abrasion powder, which contaminates the periphery of the injection molding machine. Therefore, it is conceivable to increase the hardness of the timing belt 34 to improve the durability. However, when the ejector device is operated at a high speed, noise is generated. It is also conceivable to use a chain, a rack and pinion, or the like instead of the timing belt 34, but the control accuracy is low, and play occurs, so that the ejector device cannot be operated at high speed and lubrication is required. Therefore, the periphery of the ejector device is soiled.

An object of the present invention is to provide an ejector device which can solve the problems of the above-mentioned conventional ejector device, can improve durability, and does not stain the periphery of the injection molding machine.

[0018]

For this purpose, in the ejector device of the present invention, there is provided a movable platen which is arranged to be movable back and forth along a tie bar in opposition to a fixed platen.
A motor frame fixed to the movable platen via a guide post, a stator fixed to the motor frame, a rotor disposed inside the stator, a hollow shaft fixed to the rotor, A ball nut fixed to the shaft, a ball screw shaft screwed with the ball nut, and advanced and retracted with the rotation of the ball nut; and a ball screw shaft fixed to the ball screw shaft, and the motor frame and the movable platen. And a crosshead disposed between the guide posts and stopped by the guide posts.

In another ejector device of the present invention,
Further, the hollow shaft has a first portion formed inside the rotor, and a second portion formed closer to the movable platen than the first portion and having a larger diameter than the first portion,
The ball nut is disposed on the second portion.

In still another ejector device according to the present invention, the hollow shaft further includes a third portion formed on a side farther from the movable platen than the first portion and having a smaller diameter than the first portion. Then, a rotation speed sensor is provided in the third portion. In still another ejector device of the present invention, the hollow shaft further includes a third portion formed on a side farther from the movable platen than the first portion and having a smaller diameter than the first portion. A greasing hole is provided in the third part.

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view of a main part of an ejector device according to an embodiment of the present invention.
7 is a schematic view of an ejector device according to an embodiment of the present invention, FIG. 7 is a sectional view taken along line VV of FIG. 6, and FIG. 8 is a sectional view taken along line WW of FIG.

In the figure, reference numeral 11 denotes a movable platen,
Front end of the movable platen 11 (right end in FIGS. 1 and 6)
A movable mold (not shown) is attached to the dies. The movable platen 11 is advanced and retracted by a toggle mechanism 14 along a tie bar 12 provided between a fixed platen (not shown) and the toggle support 101. An ejector pin feeder 16 is provided at the rear end (left end in FIGS. 1 and 6) of the movable platen 11. In the ejector pin feeder 16, a front end of the guide post 18 is fixed to a surface of the movable platen 11 facing the toggle support 101, and a servo motor 102 is fixed to a rear end of the guide post 18 by bolts 103.

The servo motor 102 includes a stator 105 fixed to a motor frame 104,
5 and a rotor 107 arranged close to the inside of the stator 105. By supplying a current to the coil 106, the rotor 107 can be rotated. Further, the motor frame 104 is mounted on the front plate 1.
04a, rear plate 104b, side plate 104
c, and the front plate 104a and the rear plate 104b
And a clamp rod 138 for coupling and tightening. In addition, as the servomotor 102, an inductive type,
Various types such as a synchronous type can be used.

A hollow shaft 110 is fixed further inside the rotor 107, and both ends of the hollow shaft 110 are rotatably supported by the motor frame 104 by bearings 111 and 112. The hollow shaft 110 has a medium diameter portion 115 as a first portion disposed inside the rotor 107, and a large diameter portion as a second portion formed on the movable platen 11 side from the medium diameter portion 115. 116, and a small diameter portion 117 as a third portion formed on the toggle support 101 side with respect to the middle diameter portion 115, and a ball nut 120 is fixed inside the large diameter portion 116.

A ball screw shaft 121 is provided so as to be screwed with the ball nut 120.
The crosshead 25 is fixed to the front end by a nut 123, and the ejector rod 27 is fixed to the crosshead 25. Then, the cross head 25 is prevented from rotating by the guide post 18. Therefore, by driving the servo motor 102 and rotating the rotor 107, the ball nut 120 is rotated in the direction of arrow F, and the ball nut 120 and the ball screw shaft 121 are rotated.
Thus, the rotary motion can be converted into a linear motion, and the crosshead 25 can be moved back and forth along the guide post 18 in the direction of arrow A. As a result, the ejector rod 27 and the ejector pin (not shown) can be moved in the same direction.

In this case, the crosshead 25 and the ejector rod 27 must be advanced and retracted by a stroke S necessary for projecting a molded product (not shown) by the ejector pin. Therefore, the movable platen 11 A concave portion 11a having a desired depth is formed.
In addition, since the ball screw shaft 121 is advanced and retracted by the stroke S by rotating the ball nut 120, a hollow portion 110a having a length corresponding to the stroke S is formed inside the middle diameter portion 115. .

As described above, in the present embodiment, the rotary motion generated by the servomotor 102 is converted into a linear motion, and the ejector pin feeder 16 is directly operated. There is no need to use it. Therefore, the durability of the ejector device can be improved, and the periphery of the injection molding machine is not stained.

Then, the servo motor 102 is moved so that the ball screw shaft 121 moves forward and backward in the hollow shaft 110.
And the ball screw shaft 121 are integrated, the servo motor 102 is made flat, and the crosshead 25 is formed in the recess 11 a of the movable platen 11.
, The size of the ejector pin feeder 16 in the axial direction can be reduced. Also,
A rotor 107 is provided outside the middle diameter portion 115 of the hollow shaft 110,
Since the ball nut 120 is disposed inside the large diameter portion 116, the rotor 107 and the ball nut 12 are arranged in the radial direction.
0 can be overlapped. Therefore,
The radial dimension of the ejector pin feeder 16 can be reduced.

As a result, since the ejector pin feeding device 16 can be disposed inside the toggle mechanism 14, the size of the mold clamping device can be reduced. In order to control the servomotor 102, an encoder 131 as a rotation speed sensor is fixed to a rear end of the hollow shaft 110,
The rotation speed of the rotor 107 can be directly detected by the encoder 131. Therefore, the position of the crosshead 25 can be accurately detected. In addition, a proximity switch 135 is provided on the movable platen 11 to detect the retreat limit position of the crosshead 25. The proximity switch 135 can be reset each time molding is performed. In addition,
A limit switch can be used in place of the proximity switch 135.

Further, since the hollow shaft 110 and the ball nut 120 are rotated by driving the servo motor 102, if the inertia is large, a delay may occur when controlling the rotation speed. Therefore, the hollow shaft 110 and the ball nut 120 are made thinner to reduce the inertia. Further, in order to reduce the frictional resistance between the ball nut 120 and the ball screw shaft 121, the two are lubricated with grease.
A greasing hole 132 is formed in the small-diameter portion 117, and a communication passage 133 that connects the greasing hole 132 and the hollow portion 110a is formed in the small-diameter portion 117 so that grease can be supplied. It has become.

The present invention is not limited to the above embodiment, 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.

[0032]

As described above in detail, according to the present invention, in the ejector device, the movable platen is provided so as to be able to advance and retreat along the tie bar in opposition to the fixed platen, and to guide the movable platen to the movable platen. A motor frame fixed via a post, a stator fixed to the motor frame, and a rotor disposed inside the stator;
A hollow shaft fixed to the rotor, a ball nut fixed to the hollow shaft, a ball screw shaft screwed with the ball nut, and advanced and retracted with the rotation of the ball nut; fixed to the ball screw shaft And a crosshead disposed between the motor frame and the movable platen and prevented from rotating by the guide post.

In this case, since the rotary motion generated by the rotor is converted into linear motion by the ball nut and the ball screw shaft, the ejector pins can be moved forward and backward, so that it is not necessary to use a timing belt. Therefore, the durability of the ejector device can be improved, and the periphery of the injection molding machine is not stained.

Further, since the ball screw shaft is advanced and retracted in the hollow shaft, the axial dimension of the ejector pin feeder can be reduced. Therefore, the size of the mold clamping device can be reduced.

In another ejector device of the present invention,
Further, the hollow shaft has a first portion formed inside the rotor, and a second portion formed closer to the movable platen than the first portion and having a larger diameter than the first portion,
The ball nut is disposed on the second portion.

In this case, the rotor and the ball nut can be overlapped in the radial direction. Therefore, the radial dimension of the ejector pin feeder can be reduced.

[0037] In still another ejector device of the present invention, the hollow shaft further has a third portion formed on a side farther from the movable platen than the first portion and having a smaller diameter than the first portion. Then, a rotation speed sensor is provided in the third portion. In this case, since the rotation speed of the rotor can be directly detected, the position of the crosshead can be accurately detected.

[0038] In still another ejector device of the present invention, the hollow shaft has a third portion formed on a side farther from the movable platen than the first portion and having a smaller diameter than the first portion. Then, a greasing hole is provided in the third portion. In this case, lubrication can be performed between the ball nut and the ball screw shaft provided inside the hollow shaft.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of an ejector device according to an embodiment of the present invention.

FIG. 2 is a front view of a conventional one-axis type ejector device.

FIG. 3 is a side view of a conventional one-axis type ejector device.

FIG. 4 is a front view of a conventional two-axis type ejector device.

FIG. 5 is a side view of a conventional two-axis type ejector device.

FIG. 6 is a schematic diagram of an ejector device according to an embodiment of the present invention.

FIG. 7 is a sectional view taken along line VV of FIG. 6;

FIG. 8 is a sectional view taken along line WW of FIG. 6;

[Explanation of symbols]

 Reference Signs List 11 movable platen 11a recess 12 tie bar 14 toggle mechanism 25 cross head 101 toggle support 102 servo motor 107 rotor 110 hollow shaft 115 medium diameter section 116 large diameter section 117 small diameter section 120 ball nut 121 ball screw shaft 131 encoder 132 greasing hole

Claims (4)

(57) [Claims] 1. A movable platen which is arranged to be able to advance and retreat along a tie bar in opposition to a fixed platen, and (b) fixed to the movable platen via a guide post.
And a motor frame, and (c) a stator fixed to the motor frame, (d) a rotor disposed inside of the stator, a hollow shaft fixed to (e) said rotor, (f) the a ball nut fixed to the hollow shaft, (g) the ball nut and screwed, a ball screw shaft is advanced and retracted with rotation of the ball nut, Rutotomoni fixed to (h) said ball screw shaft, said Mo
Disposed between the movable frame and the movable platen,
An ejector device comprising: a crosshead that is prevented from rotating by a post . 2. The hollow shaft includes a first portion formed inside the rotor, and a second portion formed on the movable platen side of the first portion and having a larger diameter than the first portion. The ejector device according to claim 1, wherein the ball nut is disposed on the second portion. 3. The hollow shaft has a third portion formed on a side farther from the movable platen than the first portion and having a smaller diameter than the first portion, and a rotation speed sensor is provided on the third portion. The ejector device according to claim 2, wherein the ejector is disposed. 4. The hollow shaft is formed on a side farther from the movable platen than the first portion, has a third portion smaller in diameter than the first portion, and has a greasing hole in the third portion. The ejector device according to claim 2, wherein the ejector is disposed.