JP2008307739A - Mold clamping apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold clamping apparatus capable of performing a stable holding of a ball screw of a mold opening/closing mechanism or a stable movement of a movable platen in opening/closing the mold. <P>SOLUTION: In the mold clamping apparatus 11, the mold opening/closing mechanism 28 which is equipped with an electric motor 29 for rotating either a ball screw 32 or ball screw nut 34, the ball screw 32 nonmovably disposed in the axial direction with respect to a first platen 16, the ball screw nut 34 relatively movably disposed with respect to the ball screw 32, the movable platen 18 having the ball screw nut 34, and a bearing part 33 which is disposed on a second platen 20 and movably holds the end part 32a or the vicinity of the end part of the ball screw 32 in the axial direction, is separately disposed from a mold clamping mechanism 23. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a mold clamping device used for injection molding, a press machine, and the like, and in particular, a mold clamping mechanism provided with a mold opening / closing mechanism including a ball screw, a ball screw nut, and an electric motor separately from the mold clamping mechanism. It relates to the device.

As a mold clamping device in which a mold opening / closing mechanism including a ball screw, a ball screw nut, and an electric motor is provided separately from the mold clamping mechanism, those described in Patent Documents 1 and 2 are known. In the mold opening / closing mechanism of Patent Document 1, a ball screw is fixedly disposed on a base, a ball screw nut is attached to a movable die plate, and the ball screw nut and the movable die plate are moved in the mold opening / closing direction by rotation of the ball screw. . However, in Patent Document 1, the ball screw nut can be attached only to a relatively low position of the movable die plate, and the movement of the movable die plate becomes unstable when the mold is opened and closed. There was a problem that parallelism could not be maintained and the movable die plate could not move at high speed.

Further, in Patent Document 2, a servo motor is attached to a fixed plate, a nut member is attached to a connecting plate that is a part of the movable platen, and the nut member and the connecting plate are moved in the mold opening / closing direction by rotation of the drive shaft. However, in the mold opening / closing mechanism of Patent Document 2, the drive shaft (screw portion) is inserted through the nut member of the connecting plate, but the end portion is not held. Therefore, the drive shaft (screw portion) is likely to cause rotational vibration, and the burden on the nut member and the connecting portion between the drive shaft and the servo motor is large.

JP 2002-154146 A (Claim 1, FIG. 1) JP-A-10-258450 (0024, FIG. 1)

In the present invention, in view of the above problems, in a mold clamping device in which a mold opening / closing mechanism including a ball screw, a ball screw nut, and an electric motor is provided separately from the mold clamping mechanism, the ball screw of the mold opening / closing mechanism is stably held. Another object is to provide a mold clamping device capable of stably moving the movable platen when the mold is opened and closed. In particular, for a mold clamping device in which a mold clamping mechanism is disposed between the movable platen and the pressure receiving plate, a mold that can stably hold the ball screw, or can move the movable plate stably when the mold is opened and closed. An object is to provide a fastening device.

The mold clamping apparatus according to claim 1 of the present invention is a mold clamping apparatus in which a mold opening / closing mechanism including a ball screw, a ball screw nut, and an electric motor is provided separately from the mold clamping mechanism. Or an electric motor that rotates any of the ball screw nuts, a ball screw disposed so as not to move in the axial direction with respect to the first board, a ball screw nut disposed so as to be relatively movable with respect to the ball screw, A movable board to which a ball screw nut is attached, and a bearing part which is disposed on the second board and holds the end of the ball screw or the vicinity of the end so as to be movable in the axial direction are provided.

The mold clamping apparatus according to claim 2 of the present invention is a mold clamping apparatus in which a mold opening / closing mechanism provided with a ball screw, a ball screw nut, and an electric motor is provided separately from the mold clamping mechanism. An electric motor disposed on the board, a ball screw disposed rotatably by the electric motor and immovable in the axial direction, a ball screw nut disposed movably with respect to the ball screw,
A movable platen provided with the ball screw nut, and a bearing portion provided on the pressure receiving plate and configured to hold the end portion of the ball screw or the vicinity of the end portion so as to be rotatable and movable in the axial direction. To do.

The mold clamping device according to claim 3 of the present invention is characterized in that, in claim 1 or 2, the mold clamping mechanism is disposed between the movable platen and the pressure receiving platen.

A mold clamping device according to the present invention includes, in addition to the mold clamping mechanism, an electric motor that rotates either a ball screw or a ball screw nut, a ball screw that is axially immovable with respect to the first panel, and a ball screw. A ball screw nut that is relatively movable with respect to the movable platen, a movable plate to which the ball screw nut is attached, and an end portion or a vicinity of the end portion of the ball screw that is arranged on the second plate so as to be movable in the axial direction. Since the mold opening / closing mechanism including the bearing portion is provided, the ball screw can be stably held, and the movable platen can be stably moved when the mold is opened and closed.

The mold clamping device of the present invention will be described with reference to FIGS. FIG. 1 is a front view of the mold clamping device of the present embodiment. FIG. 2 is a view of the movable platen as viewed from the direction of arrow A in FIG. FIG. 3 is an enlarged cross-sectional view of a ball screw bearing portion in the pressure receiving plate, showing a state other than during mold clamping. FIG. 4 is an enlarged cross-sectional view of a ball screw bearing portion in the pressure receiving plate and shows a state during mold clamping.

As shown in FIG. 1, the mold clamping device 11 of the present embodiment is used for mold clamping of an injection molding machine 12 and is disposed on a base 13 together with an injection device 14. The mold clamping device 11 includes a fixed plate 16 that is a first plate, a pressure receiving plate 20 that is a second plate, and a movable plate 18 that is a third plate. A stationary mold 15 is attached to the stationary platen 16, a movable mold 17 is attached to the movable platen 18, and a clamping cylinder 19 is disposed on the pressure receiving plate 20. A tie bar 21 is disposed in parallel between the fixed plate 16 and the pressure receiving plate 20. The movable platen 18 has the tie bars 21 inserted in the vicinity of the four corners thereof, and the lower part thereof is slidably mounted on a guide 22 on the base 13 so as to be movable in the mold opening / closing direction.

The mold clamping mechanism 23 is disposed between the movable platen 18 and the pressure receiving plate 20, and a ram 24 is fixed toward the pressure receiving plate 20 at a substantially center of the back side of the mold mounting surface of the movable platen 18. On the other hand, the pressure receiving plate 20 is provided with a cylinder cylinder 19a of a clamping cylinder 19, and the ram 24 is inserted into the cylinder cylinder 19a. The mold clamping cylinder 19 can be supplied and discharged with pressure oil from a hydraulic mechanism (not shown). The mold clamping mechanism includes a mold clamping mechanism composed of other hydraulic cylinders using a booster mechanism and a half nut mechanism, a mold clamping mechanism using an electric motor, a mold clamping mechanism using both an electric motor and hydraulic pressure, and a toggle mold clamping mechanism. The one used may be used.

The mold opening / closing mechanism 28 is disposed across the fixed platen 16, the movable platen 18, and the pressure receiving plate 20, and as shown in FIG. 2, the upper tie bar 21 on the operation side B of each of the plates 16, 18, and 20 is provided. Are disposed on the obliquely upper side surface and on the obliquely lower side surface with respect to the lower tie bar 21 on the counter-operation side C. As a result, when the movable platen 18 is moved, it is possible to stably move the movable platen 18 by transmitting a force to the movable platen 18 from two diagonal positions. The position where the mold opening / closing mechanism 28 is disposed is determined in consideration of the workability of taking out the molded product and replacing the mold, but it may be the upper surface of the movable platen or the side surface of the intermediate portion. In addition, it is desirable to provide two mold opening / closing mechanisms as in the present embodiment. However, one is required for small machines, and three or more are provided when high parallelism is required for mold opening / closing in large machines or foam molding. Also good.

In the mold opening / closing mechanism 28, a mold opening / closing servomotor 29, which is an electric motor, is fixed to a bracket 31 provided to protrude from the side surface of the stationary platen 16. The mold opening / closing servomotor 29 is provided with a rotary encoder 30 so that the position of the movable platen 18 relative to the fixed platen 16 can be detected. A ball screw 32 is coaxially fixedly connected to the motor shaft of the mold opening / closing servomotor 29. Therefore, the ball screw 32 is disposed so as to be rotatable and immovable in the axial direction by the mold opening / closing servomotor 29. The small diameter portion 32 a at the other end of the ball screw 32 is held by the bearing portion 33 of the pressure receiving plate 20. Further, a ball screw nut 34 is fixed to the bracket 25 provided to project from the side surface of the movable platen 18, and the movable platen 18 and the ball screw nut 34 are disposed so as to be movable relative to the ball screw 32. The electric motor is not limited to the mold opening / closing servo motor 29, and the rotation transmission mechanism may be a rotation transmission mechanism that transmits the rotation to the ball screw via a pulley or a reduction gear.

As shown in FIGS. 3 and 4, a bracket 26 projects from the side surface of the pressure receiving plate 20. A concave hole 27 is provided on the surface of the bracket 26 on the movable platen side, and a bearing portion 33 is inserted into the hole 27. A mounting plate 35 is fixed around the hole 27 of the bracket 26 by a bolt 36 to fix the bearing portion 33. The bearing portion 33 is a rolling guide having an outer cylinder member 37 that is fixedly inserted into the hole 27 and an inner cylinder member 38 that can perform a rotational motion and a reciprocating motion with respect to the outer cylinder member 37. It is a member. The inner cylinder member 38 is provided with bearings 39 that are rotatable in a plurality of rows in a staggered manner on the inner cylinder member 38, and the load can be evenly distributed by the rolling guide of the bearing 39. Stoppers 40 and 40 are provided in the vicinity of both ends of the outer cylinder member 37 to prevent the inner cylinder member 38 from falling off the outer cylinder member 37. Further, rubber seals 41, 41 are provided outside the stoppers 40, 40 so that dust and the like do not enter the bearing portion 33. A small-diameter portion 32 a that is not threaded at the end of the ball screw 32 is inserted into the inner cylinder member 38. In this embodiment, a part of the small diameter portion 32 a protrudes from the hole of the outer cylinder member 37 into the hole 27 of the bracket 26. Note that the portion of the pressure receiving plate 20 where the ball screw 32 is held by the bearing portion 33 may be not near the end portion but near the end portion or may penetrate the bearing portion. Further, the bearing portion may have other configurations such as a radial bearing that receives a ball screw being movable in a mold opening / closing direction by a guide.

Next, the operation of the mold clamping device 11 of this embodiment will be described. After the molded product is taken out from the movable mold 17 at the mold opening position, the mold opening / closing servomotor 29 of the mold opening / closing mechanism 28 is operated, and the ball screw 32 is rotated. As the ball screw 32 rotates, the ball screw nut 34 is relatively moved in the mold closing direction, and at the same time, the movable platen 18 is also moved. At this time, since the other end of the ball screw 32 is rotatably held by the bearing portion 33 of the pressure receiving plate 20, even if the movable plate 18 moves away from the pressure receiving plate 20, the rotation speed of the ball screw 32 is allowed to be high. Thus, the end of the ball screw 32 is stably held without causing rotational shake. In the present embodiment, the movable platen 18 is held by the guide 22 on the base 13, and the ball screw nut 34 is fixed to the upper part of the operation side B and the lower part of the counter operation side C in the substantially diagonal direction. Therefore, the parallelism of the movable platen 18 with respect to the fixed platen 16 is maintained even if the movable platen 18 is moved rapidly or stopped suddenly.

Then, the fixed mold 15 and the movable mold 17 are brought into abutment with each other, or pressure oil is sent from a hydraulic mechanism (not shown) to the clamping cylinder 19 at a position slightly before the abutment. Is done. At the time of mold clamping, the tie bar 21 is extended by the mold clamping force, the pressure receiving plate 20 is moved backward, and the position of the pressure receiving plate 20 with respect to the fixed plate 16 is separated. Then, the positional relationship between the ball screw 32 and the pressure receiving plate 20 fixedly arranged in the axial direction with respect to the fixed platen 16 changes, and the pressure receiving plate 20 and the bearing portion 33 with respect to the ball screw 32 as shown in FIG. Is moved in the direction of the arrow D, and the bearing portion 33 is moved in a direction of slightly detaching from the ball screw 32. At this time, since the inner cylinder member 38 of the bearing portion 33 is movable with respect to the outer cylinder member 37 by the bearing 39, the inner cylinder member 38 is also moved into the outer cylinder member 37 together with the small diameter portion 32 a at the end of the ball screw 32. The relative positional relationship is changed. At the time of mold clamping, the positional relationship between the fixed platen 16 and the movable platen 18 is brought close by the mold clamping mechanism 23, and therefore the position of the ball screw nut 34 with respect to the ball screw 32 needs to be corrected accordingly. Therefore, by driving the mold opening / closing servomotor 29 in synchronization with the operation of the mold clamping mechanism 23, the ball screw 32 is slightly rotated in the direction in which the movable platen 18 and the ball screw nut 34 are moved in the mold closing direction.

When the mold clamping is completed, the molten resin is injected and filled from the injection device 14 into a cavity formed between the fixed mold 15 and the movable mold 17 and cooled and solidified. When the cooling time is completed, the mold clamping cylinder 19 is depressurized, and at the same time, the extension of the tie bar 21 is canceled, and the positional relationship between the stationary platen 16 and the pressure receiving plate 20 is returned to the state before mold clamping. In synchronization with this, the ball screw 32 is slightly rotated by the mold opening / closing servomotor 29 in the rotational direction for moving the movable plate 18 toward the mold opening side, and the axial positional relationship between the pressure receiving plate 20 and the ball screw 32 is also determined by the ball screw 32. Is returned to its original state while rotating. Next, pressure oil is supplied so that the mold clamping cylinder 19 operates in the mold opening direction, and the mold opening / closing servo motor 29 is operated to perform strong mold opening for a predetermined stroke. Then, when the powerful mold opening is completed, the movable platen 18 is moved in the mold opening direction by the force of only the mold opening / closing mechanism 28. In this case as well, there is an advantage that the parallelism of the movable platen 18 with respect to the fixed platen 16 can be maintained even if the movable platen 18 is rapidly moved or suddenly stopped as in the case of mold closing.

Next, another embodiment shown in FIG. 5 will be described. In the example shown in FIG. 5, the mold opening / closing mechanism 53 arranged separately from the mold clamping mechanism 52 of the mold clamping device 51 includes a pressure receiving plate 54 (in this embodiment, the pressure receiving plate 54 corresponds to the first plate). An electric motor 55 is fixed to the motor shaft of the electric motor 55. One end of the ball screw 56 is fixed to the motor shaft so as not to move in the axial direction, and the other end of the ball screw 56 is fixed to the fixed plate 57 (in this embodiment, the fixed plate 57 is the second plate). Is supported by a bearing portion 58 provided in a disk (which corresponds to the disk) and is movable in the axial direction. A ball screw nut 60 fixed to a movable plate 59 as a third plate is disposed so as to be relatively movable with respect to the ball screw 56. In the embodiment shown in FIG. 5, the ball screw 56 does not move in the axial direction with respect to the fixed platen 57 at least when the die is opened and closed, but retracts in the direction of extending the tie bar 61 together with the pressure receiving plate 54 with respect to the fixed platen 57 when the die is clamped. Accordingly, the ball screw 56 is moved in the axial direction within the bearing portion 58 disposed on the stationary platen 57.

Next, still another embodiment shown in FIG. 6 will be described. In still another embodiment shown in FIG. 6, an electric motor 75 is fixed to a movable plate 74 as a third plate as a mold opening / closing mechanism 73 arranged separately from the mold clamping mechanism 72 of the mold clamping device 71. A ball screw nut 76 that is also rotatably arranged on the movable platen 74 is rotated by the electric motor 75. One end of the ball screw 77 inserted through the ball screw nut 76 is held non-rotatable and non-movable in the axial direction by the bearing portion 82 of the fixed plate 78 which is the first plate, and the other end is the second plate. The bearing part 80 of the pressure receiving plate 79 is held so as not to rotate but to move in the axial direction. When the mold is opened and closed, the movable plate 74 is moved relative to the ball screw 77 by the rotation of the ball screw nut 76. When the mold is clamped, the tie bar 81 is extended by the mold clamping mechanism 72, and the interval between the fixed plate 78 and the pressure receiving plate 79 is widened. The ball screw 77 is moved in the axial direction without rotating with respect to the bearing portion 80 of the pressure receiving plate 79. In another embodiment shown in FIG. 6, one end of the ball screw is held in the pressure receiving plate so as not to move in the axial direction (the pressure receiving plate is used as the first plate), and the other end can be moved in the axial direction on the fixed plate. (The fixed platen is the second plate).

The present invention is not enumerated one by one, but is not limited to that of the above-described embodiment, and it goes without saying that those skilled in the art also apply modifications made in accordance with the spirit of the present invention. is there. The present invention is not limited to resin and metal injection molding machines, and can also be used for die casting machines and various press molding machines. Further, the present invention is not limited to a horizontal mold clamping device, and may be used for a vertical mold clamping device. In the case of a vertical mold clamping device, a pressure receiving plate, a movable plate, in order from the bottom, except when a fixed plate (including a grounded base plate), a movable plate, and a pressure receiving plate are arranged in this order from the bottom. Further, it may be of various arrangements such as a case where the pressure platen, the fixed platen, and the movable platen are arranged in this order from the bottom. The first board in which the ball screw is disposed so as not to move in the axial direction and the second board in which the ball screw is held so as to be movable in the axial direction may be either a fixed board or a pressure receiving board.

It is a front view of the mold clamping device of this embodiment. It is the figure which looked at the movable board from the arrow A direction in FIG. It is an expanded sectional view of the bearing part of a ball screw in a pressure board, and shows a state other than the time of mold clamping. It is an expanded sectional view of the bearing part of a ball screw in a pressure board, and shows the state at the time of mold clamping. It is a front view of the mold clamping apparatus of another embodiment. It is a front view of the mold clamping device of another embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Mold clamping apparatus 12 Injection molding machine 16 Fixed board 18 Movable board 20 Pressure receiving board 23 Mold clamping mechanism 28 Mold opening / closing mechanism 29 Mold opening / closing servo motor 32 Ball screw 33 Bearing part 34 Ball screw nut 37 Outer cylinder member 38 Inner cylinder member

Claims (3)

In addition to the mold clamping mechanism, in a mold clamping device in which a mold opening / closing mechanism including a ball screw, a ball screw nut, and an electric motor is disposed.
The mold opening / closing mechanism is
An electric motor that rotates either a ball screw or a ball screw nut;
A ball screw disposed so as not to be axially movable with respect to the first board;
A ball screw nut that is arranged to be movable relative to the ball screw;
A movable plate to which the ball screw nut is attached;
A mold clamping device comprising: a bearing portion disposed on the second board and holding an end portion of the ball screw or the vicinity of the end portion so as to be movable in the axial direction. In addition to the mold clamping mechanism, in a mold clamping device in which a mold opening / closing mechanism including a ball screw, a ball screw nut, and an electric motor is disposed.
The mold opening / closing mechanism is
An electric motor disposed on the stationary platen;
A ball screw that is rotatable by the electric motor and immovable in the axial direction;
A ball screw nut movably disposed with respect to the ball screw;
A movable platen provided with the ball screw nut;
A mold clamping device, comprising: a bearing portion disposed on a pressure receiving plate and configured to hold an end portion of the ball screw or a vicinity of the end portion so as to be rotatable and movable in an axial direction. 3. The mold clamping device according to claim 1, wherein the mold clamping mechanism is disposed between the movable platen and the pressure receiving platen.

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