JP2002301747A - Driving device of injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving device of an injection molding machine which enables lessening of the length of the whole of the device and miniaturization of the whole thereof; can use a built-in motor of a structure common to members to be driven even when the kinds of the members differ from each other; has high general-purpose properties; realizes common use of component and various devices; and thereby can reduce the cost of the manufacture and maintenance. SOLUTION: The driving device has a driving source equipped with a first hollow rotating shaft, a second hollow rotating shaft fitted to the first hollow rotating shaft and disposed therein, a screw shaft engaging with the inner peripheral surface of the second hollow rotating shaft and so provided in this shaft as to be movable back and forth, a nut 48 screwed on the screw shaft and the member to be driven which is provided for the screw shaft.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for an injection molding machine.

[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 to fill a cavity space of a mold apparatus.
A molded product is formed by cooling and solidifying the resin in the cavity space.

To this end, the mold apparatus comprises a fixed mold and a movable mold. The movable mold is moved forward and backward by a mold clamping device, and is brought into and out of contact with the fixed mold to open and close the mold. The mold can be closed, clamped and opened.

[0004] A toggle mechanism is provided in the mold clamping device for moving the movable mold forward and backward, and the toggle mechanism drives an electric motor, for example, a servomotor or the like, provided in a drive unit. Operated by

FIG. 2 is a sectional view of a driving portion of a conventional mold clamping device.

In FIG. 1, reference numeral 51 denotes a servomotor as a drive source. The servomotor 51 has a rotating shaft 52 and is attached to a fixing member (not shown) such as a toggle support. The front end (the right end in the figure) of the rotating shaft 52 is connected to the ball screw shaft 5 via a coupling 53.
6 is connected to the rear end (left end in the figure). Here, a key groove is formed on the outer peripheral surface of the rotary shaft 52 and the ball screw shaft 56 and on the inner peripheral surface of the coupling 53, and the key 54 is inserted into the key groove, so that the rotation shaft 52 is The rotation is transmitted to the ball screw shaft 56 via the coupling 53. The ball screw shaft 56 has a bearing 57 housed in a bearing housing 58 attached to a fixing member such as a toggle support (not shown).
Is supported rotatably. The bearing 57
Is fixed by a plate 59 attached to a bearing housing 58. Further, the ball screw shaft 56 is fixed to the inner peripheral portion of the bearing 57 by the nut 60, so that the ball screw shaft 56 cannot move in the axial direction.

[0007] The ball screw shaft 56 is formed with a screw over substantially the entire length of the outer periphery.
1 are screwed together. Further, the ball screw nut 6
1 is attached to a crosshead 62 of a toggle mechanism slidable along a guide bar 63.

Therefore, when the servo motor 51 is operated, the rotation of the rotary shaft 52 is transmitted to the ball screw shaft 56, and the ball screw nut 61 screwed to the ball screw shaft 56 moves in the axial direction of the ball screw shaft 56. The crosshead 62 is moved rightward or leftward in the figure.

When the crosshead 62 is advanced (moved to the right in the drawing), the toggle mechanism is extended, and the movable platen (not shown) is advanced, so that the mold is closed and the mold is clamped. Is retracted (moved to the left in the figure), the toggle mechanism is bent, the movable platen is retracted, and the mold is opened.

[0010]

However, in the conventional driving device, the front end of the rotating shaft 52 protruding forward of the servomotor 51 is connected to the rear end of the ball screw shaft 56 via the coupling 53. By moving the ball screw nut 61 screwed forward of the bearing 57 that supports the ball screw shaft 56 in the axial direction of the ball screw shaft 56, the crosshead 62 is moved forward or backward. The distance from the rear end of the servo motor 51 to the front end of the ball screw shaft 56 becomes long. That is, the length of the entire driving device is increased.

Therefore, there has been provided a driving device using a built-in motor in which a rotating shaft of a motor is hollow and a ball screw shaft is inserted into the hollow portion.

FIG. 3 is a sectional view of another conventional driving device.

In FIG. 1, reference numeral 70 denotes a servomotor as driving means, and the servomotor 70
1. A hollow rotary shaft 73 rotatably mounted on a housing of a servomotor 70 via a bearing 74, and a rotor 72 mounted on the hollow rotary shaft 73. The housing of the servomotor 70 is connected to the toggle support 8 via a bearing housing 82 and a plate 83.
4 attached.

At the rear end (left end in the figure) of the hollow rotary shaft 73, an encoder 76 for detecting the rotation of the hollow rotary shaft 73 is mounted via an encoder shaft 75. At the front end (right end in the figure) of the hollow rotary shaft 73, a male spline shaft 77 having a spline extending in the axial direction on the outer periphery of the hollow shaft is attached. Further, at the front end of the male spline shaft 77,
A female spline shaft 78 in which a spline extending in the axial direction is formed on the inner periphery of the hollow shaft is coupled.

Here, the male spline shaft 77 and the female spline shaft 78 can be moved in the axial direction because they are connected by the mutual engagement of the splines. It is transmitted to the shaft 78. Note that the female spline shaft 78 is
1 and is rotatably attached to the bearing housing 82. Further, a ball screw nut 79 is attached to the front end of the female spline shaft 78.

The ball screw nut 79 has a ball screw shaft 8 formed with a screw over substantially the entire outer circumference.
0 is screwed. At the front end of the ball screw shaft 80, it is attached to a crosshead 85 of a toggle mechanism slidable along a guide bar (not shown). Since the cross head 85 slides along the guide bar and cannot be rotated, the ball screw shaft 80 is not rotatable.
Cannot rotate.

Therefore, when the servo motor 70 is operated, the rotation of the hollow rotary shaft 73 is
9, the ball screw shaft 80 screwed into the ball screw nut 79 moves back and forth in the axial direction, so that the crosshead 85 is moved forward or backward.

In this case, when the cross head 85 is retracted, most of the ball screw shaft 80 is
3. The distance from the rear end of the servomotor 70 to the crosshead 85 is shortened because it is housed in the male spline shaft 77 and the female spline shaft 78. That is, the length of the entire driving device can be reduced, and the entire driving device can be downsized. Further, the length of the ball screw shaft 80 can be made sufficiently long so that the crosshead 85 can be advanced to the position of 85 'shown in the figure.

FIG. 4 is a sectional view of still another conventional driving device. In addition, about what has the same structure as the drive device shown in FIG. 3, by attaching the same code | symbol,
The description is omitted.

In this case, the housing of the servo motor 70 is attached to the movable platen 98 via the plate 91. A female spline hollow shaft 87 inserted into the hollow rotary shaft 73 is provided at the rear end of the hollow rotary shaft 73.
Flange is attached. An encoder 76 is attached to the flange via an encoder shaft 75.

The female spline hollow shaft 87 is
A spline extending in the axial direction is formed on the inner circumference,
A male spline portion 88 of a ball screw shaft 89 having an axially extending spline formed on the outer periphery is coupled. Since the female spline hollow shaft 87 and the male spline portion 88 are connected by engaging each other splines,
The female spline shaft 87 is movable with respect to each other in the axial direction.
Is transmitted to the ball screw shaft 89. Further, a screw is formed in a portion of the outer periphery of the ball screw shaft 89 ahead of the male spline portion 88.

Here, a ball screw nut 90 attached to a plate 91 is screwed to the ball screw shaft 89. A movable housing 93 slidable along a guide bar 96 is provided at the front end of the ball screw shaft 89.
Are mounted via bearings 92. The front end of the ball screw shaft 89 is fixed to an inner peripheral portion of the bearing 92 by a nut 97. A movable block 94 is attached to the movable housing 93. Further, an ejector (not shown) for projecting into a cavity inside the movable mold of the mold device to eject a molded product is provided at a central portion of the movable block 94. An ejector rod 95 for moving the pin is attached.

Therefore, when the servo motor 70 is operated, the rotation of the hollow rotary shaft 73 is transmitted to the ball screw shaft 89, so that the ball screw shaft 89 screwed into the ball screw nut 79 attached to the plate 91 rotates. While moving in the axial direction. Therefore, the ejector rod 95 attached to the movable housing 93 via the movable block 94 is moved forward or backward. Since the movable housing 93 is attached to the ball screw shaft 89 via the bearing 92, the ball screw shaft 89
Is not transmitted to the movable housing 93 and the ejector rod 95.

In this case as well, similarly to the drive device shown in FIG.
Since the distance to 5 is shortened, the entire length of the driving device can be shortened, and the entire driving device can be downsized.

However, the conventional driving devices shown in FIGS. 3 and 4 both use a built-in motor in which the rotating shaft of the motor is hollow and a ball screw shaft is inserted into the hollow portion, so that the entire driving device can be reduced in size. Although the driving mechanism is achieved, the driving device shown in FIG. 3 in which the driven member is the crosshead 85 and the driving device shown in FIG. 4 in which the driven member is the ejector rod 95 have a built-in motor structure. Are different. As described above, in the conventional drive device, although the miniaturization is achieved by using the built-in motor, the built-in motor having a different structure must be used according to the driven member, and versatility is required. Because of the lack, it is impossible to achieve commonality of parts and various devices and reduce manufacturing costs and maintenance costs.

The present invention solves the above-mentioned problems of the conventional driving device, and can shorten the entire length of the driving device.
The entire drive unit can be reduced in size, and a built-in motor with a common structure can be used even if the types of driven members are different, which makes it highly versatile and achieves commonality of parts and various devices. It is another object of the present invention to provide a drive device for an injection molding machine that can reduce manufacturing costs and maintenance costs.

[0027]

For this purpose, a drive device for an injection molding machine according to the present invention comprises a first hollow rotary shaft, a drive source having one end mounted on a mounting member, and Attached to the mounting member side of the hollow rotating shaft,
A second hollow rotary shaft disposed in the first hollow rotary shaft is engaged with an inner peripheral surface of the second hollow rotary shaft, and is disposed in the second hollow rotary shaft so as to be movable forward and backward. A screw shaft that is provided and protrudes toward the mounting member side of the drive source; a nut that is mounted on the mounting member side of the drive source and is screwed to the screw shaft; and a screw shaft that is mounted on the mounting member side. And a driven member disposed at the same position.

In another driving apparatus for an injection molding machine according to the present invention, the driven member is rotatably supported by the screw shaft.

In still another driving apparatus for an injection molding machine according to the present invention, a rotation detecting means is provided at an end of the first hollow rotary shaft opposite to a mounting member of the driving source.

[0030]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 5 is a schematic view of a mold clamping device of an injection molding machine according to an embodiment of the present invention.

In the drawing, reference numeral 15 denotes a frame, 13 denotes a fixed platen fixed to the frame 15, and 23 denotes a fixed platen 13 and a predetermined distance between the fixed platen 13 and is movably disposed with respect to the frame 15. A toggle support 14 as a base plate, a tie bar 14 is provided between the fixed platen 13 and the toggle support 23, and a tie bar 12 is disposed to face the fixed platen 13 and moves forward and backward along the tie bar 14 (FIG. (A movable platen in the left and right directions). A fixed mold (not shown) is attached to a surface of the fixed platen 13 facing the movable platen 12, and a movable mold (not shown) is attached to a surface of the movable platen 12 facing the fixed platen 13.

A driving device 10 is attached to the rear end (left end in the figure) of the movable platen 12. The drive device 10 has a motor 11 as a drive source, and moves an ejector rod 24 as a driven member forward or backward (moves rightward or leftward in the figure). When the ejector rod 24 moves forward or backward, an ejector pin (not shown) for ejecting a molded product by projecting into a cavity inside the movable mold in the mold apparatus is moved forward or backward. Here, the motor 11 may be any type of motor, but is preferably a servo motor.

A toggle mechanism 18 is mounted between the movable platen 12 and the toggle support 23.
A driving device 10 'is attached to the rear end of the toggle support 23 as driving means for clamping the injection molding machine. The driving device 10 'includes a motor 11' as a driving source.
The toggle mechanism 18 can be operated by moving the crosshead 17 as a driven member forward and backward. As a result, the movable platen 12 is moved forward (moved rightward in the drawing) to close the mold, and a mold clamping force is generated by multiplying the propulsive force of the motor 11 'by the toggle magnification. The mold is clamped by force. In the present embodiment, the mold clamping force is generated by operating the toggle mechanism 18, but the motor 1 is used without using the toggle mechanism 18.
The propulsion force by 1 'can be transmitted to the movable platen 12 as the mold clamping force as it is.

The toggle mechanism 18 includes a toggle lever 21 swingably supported with respect to the crosshead 17,
It comprises a toggle lever 22 swingably supported by the toggle support 23 and a toggle arm 16 swingably supported by the movable platen 12, between the toggle levers 21 and 22, and by a toggle. The link between the lever 22 and the toggle arm 16 is linked.

Next, the driving device 10 will be described. The driving device 10 attached to the movable platen 12 and the driving device 1 attached to the toggle support 23
In the case of 0 ', the structure and operation are the same except that the driven member is different. Therefore, here, the driving device 10 attached to the movable platen 12 and the driven member being the ejector rod 24 will be described.

FIG. 1 is a sectional view of a driving device mounted on a movable platen according to an embodiment of the present invention.

In the figure, a motor 11 as a driving source
Has a hollow rotary shaft 33 as a first hollow rotary shaft rotatably mounted on a housing of the motor 11 via a stator 31 and a bearing 34, and a rotor 32 mounted on the hollow rotary shaft 33. The front end (right end in the figure) of the housing of the motor 11 is attached via a plate 43 to the movable platen 12 as an attachment member.

At the rear end (left end in the figure) of the hollow rotary shaft 33, an encoder 36 as rotation detecting means for detecting the rotation of the hollow rotary shaft 33 is attached via an encoder shaft 35. In addition, the end of the hollow rotary shaft 33 opposite to the encoder 36, that is,
A second end inserted into the hollow rotary shaft 33 is provided at the front end.
The flange of the female spline hollow shaft 37 as the hollow rotary shaft is mounted.

Here, the female spline hollow shaft 37 has a shape in which both ends are opened on one surface of a donut-shaped flange having a hole at the center, and a cylindrical portion shorter than the hollow rotary shaft 33 is attached. The cylindrical portion has an outer diameter slightly smaller than the inner diameter of the hollow rotary shaft 33, and has a large diameter portion having an inner diameter substantially equal to the inner diameter of the hole of the flange, and an inner diameter smaller than the inner diameter of the large diameter portion. And an inner surface comprising a small-diameter portion.
In addition, a spline extending in the axial direction is formed in the small diameter portion. Then, from the front end side of the hollow rotary shaft 33, the distal end of the cylindrical portion is inserted toward the rear end, and one surface of the flange is attached to the front end surface of the hollow rotary shaft 33, whereby the female spline hollow shaft 37 is Attached to the shaft 33.

A ball screw shaft 41 is inserted into the female spline hollow shaft 37 as a screw shaft having a male spline portion 38 in which a spline extending in the axial direction is formed on the outer periphery of the rear end portion. The male spline portion 38 is engaged with the small diameter portion of the female spline hollow shaft 37. Since the female spline hollow shaft 37 and the male spline portion 38 are engaged with each other by engaging the splines, the female spline hollow shaft 37 and the male spline portion 38 can move in the axial direction. Is transmitted. Thus, the rotation of the female spline hollow shaft 37 is transmitted to the ball screw shaft 41. Here, a screw is formed in a portion of the outer periphery of the ball screw shaft 41 which is forward of the male spline portion 38. The outer diameter of the portion where the screw is formed is smaller than the inner diameter of the large diameter portion of the female spline hollow shaft 37.

A ball screw nut 42 as a nut attached to the plate 43 is screwed into a portion of the ball screw shaft 41 protruding from the front end of the housing of the motor 11.

Also, at the front end of the ball screw shaft 41,
A movable housing 44 slidable along the guide bar 46 is mounted via a bearing 45. Although the guide bar 46 has a rear end portion attached to the plate 43, a front end portion may be attached to the movable platen 12.

The front end of the ball screw shaft 41 is fixed to the inner peripheral portion of the bearing 45 by a nut 48. Thereby, the ball screw shaft 41 and the movable housing 4
4 are connected to each other so as to be rotatable with each other but not to be movable in the axial direction. Since the movable housing 44 is prevented from rotating by the guide bar 46, the ball screw shaft 41 moves forward and backward, that is,
Only the linear movement in the axial direction is transmitted to the movable housing 44.

Further, a movable block 47 is attached to the movable housing 44, and an ejector rod 24 is attached to a central portion of the movable block 47.
Here, the movable housing 44, the movable block 47 and the ejector rod 24 constitute a driven member.

Next, the operation of the driving device having the above configuration will be described.

First, when a current is supplied to the coil of the stator 31 to drive the motor 11, the rotor 32 rotates, and the hollow rotary shaft 33 attached to the rotor 32 rotates. Then, the rotation is transmitted to the encoder 36 via the encoder shaft 35 attached to the rear end of the hollow rotary shaft 33. Thereby, the rotation of the hollow rotary shaft 33 is detected.

On the other hand, the rotation of the hollow rotary shaft 33 is performed by a flange attached to the front end of the hollow rotary shaft 33.
The power is transmitted to the female spline hollow shaft 37. The rotation of the female spline hollow shaft 37 is transmitted to the ball screw shaft 41 by the male spline portion 38 connected to the small diameter portion by a spline.

Here, the ball screw shaft 41 is
3 is screwed into the ball screw nut 42 attached to
And since the ball screw nut 42 is fixed,
By rotating, it moves in the axial direction, ie, moves forward or backward. Whether to advance or retreat is determined by the direction of the screw and the rotation direction of the ball screw shaft 41. In the state shown in FIG. 1, the ball screw shaft 41 is located at the rearmost end, and it is possible to retreat further. Since it is not possible, here, the case of moving forward will be described.

When the ball screw shaft 41 moves forward,
The movable housing 44, the movable block 47 attached to the movable housing 44, and the ejector rod 24 attached to the movable block 47 move forward. Although the ball screw shaft 41 and the movable housing 44 are rotatable with each other, they are immovably connected to each other in the axial direction, and the movable housing 44 is prevented from rotating by a guide bar 46. 41
The rotation of the movable housing 44 which is a driven member,
It is not transmitted to the movable block 47 and the ejector rod 24.

As a result, the ejector pin (not shown) moves forward and projects into the cavity inside the movable mold of the mold apparatus to eject the molded product.

In the present embodiment, the case where one member constituting the driven member is the ejector rod 24 has been described, but the same applies when the member is the crosshead 17. That is, the crosshead 17 is attached to the movable block 47 via a long connecting member extending in the horizontal direction in FIG.
7 is changed to an elongated shape extending in the lateral direction in FIG.
The crosshead 17 can be moved forward or backward by the driving device 10. Further, the driving device 10 can move the movable member forward or backward by attaching various movable members and members attached thereto in the injection molding machine as driven members.

As described above, in the present embodiment, the movable platen 12 and the ball screw nut 42 are attached to the front end of the housing of the motor 11 and the female spline hollow shaft 3 spline-coupled to the ball screw shaft 41.
7 is inserted and fixed from the front end of the hollow rotary shaft 33, while an encoder 36 is attached to the rear end of the hollow rotary shaft 33. Further, a movable housing 44 for moving the driven member forward or backward is attached to the front end of the ball screw nut 42 via a bearing 45.

Therefore, not only is the entire length of the drive unit 10 short, the whole drive unit 10 is downsized, but also various driven members can be moved forward or backward only by replacing members such as the movable block 47. Highly versatile because it can. Therefore, the motor 11 can be shared.
The manufacturing cost and maintenance cost of the driving device 10 can be reduced.

Further, since the attachment and detachment of the drive unit 10 to and from the fixing member and the attachment and detachment of the encoder 36 become easy, the maintainability of the drive unit 10 is high and the maintenance cost can be reduced.

It should be noted that the present invention is not limited to the above-described 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.

[0057]

As described above in detail, according to the present invention, a driving device for an injection molding machine has a first hollow rotating shaft, and a driving source whose one end is mounted on a mounting member. A second hollow rotary shaft attached to the mounting member side of the first hollow rotary shaft and disposed in the first hollow rotary shaft; and an inner peripheral surface of the second hollow rotary shaft. Engaging and disposed in the second hollow rotating shaft so as to be able to advance and retreat,
A screw shaft protruding to the mounting member side of the drive source, a nut attached to the mounting member side of the drive source, and screwing with the screw shaft; and a nut disposed on the mounting member side of the screw shaft. And a driven member.

In this case, the entire length of the driving device is short, so that not only the entire driving device is downsized, but also various driven members can be moved forward or backward only by replacing the mounting member. High versatility. Therefore, a common drive source can be used, and the manufacturing cost and maintenance cost of the drive device can be reduced.

Further, the drive device can be easily attached to and detached from the mounting member, so that the maintainability of the drive device is high and the maintenance cost can be reduced.

In still another driving device for an injection molding machine, a rotation detecting means is further provided at an end of the first hollow rotary shaft opposite to a mounting member of the driving source.

In this case, the attachment and detachment of the rotation detecting means can be easily performed, so that the maintenance of the driving device is high and the maintenance cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a driving device attached to a movable platen according to an embodiment of the present invention.

FIG. 2 is a sectional view of a driving unit of a conventional mold clamping device.

FIG. 3 is a sectional view of another conventional driving device.

FIG. 4 is a sectional view of still another conventional driving device.

FIG. 5 is a schematic view of a mold clamping device of the injection molding machine according to the embodiment of the present invention.

[Explanation of symbols]

 10 Drive 48 Nut

Claims (3)

[Claims] 1. A drive source comprising: (a) a first hollow rotary shaft, one end of which is mounted on a mounting member; and (b) the first hollow rotary shaft.
A second hollow rotary shaft attached to the mounting member side of the hollow rotary shaft, and disposed in the first hollow rotary shaft;
(C) a screw shaft that engages with the inner peripheral surface of the second hollow rotary shaft, is disposed so as to be able to advance and retreat within the second hollow rotary shaft, and protrudes toward the mounting member of the drive source. (D) a nut attached to the attachment member side of the drive source and screwed to the screw shaft; and (e) a driven member disposed on the attachment member side of the screw shaft. A driving device for an injection molding machine. 2. The driving device for an injection molding machine according to claim 1, wherein the driven member is rotatably supported by the screw shaft. 3. The drive device for an injection molding machine according to claim 1, wherein the rotation detecting means is provided at an end of the first hollow rotary shaft on a side opposite to a mounting member of the drive source.