JP2001212828A - Mold clamping device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold clamping device which can prevent the lowering of parallelism between a movable platen and fixed platen and the deformation of the movable platen and a movable mold caused by the installation and operation of an ejector mechanism and mold a molding having a desired shape and dimensions. SOLUTION: An auxiliary platen 13 which is fitted with a ball screw shaft 96 and a driving means 112 for rotating the shaft 96 and supported movably by tie-bars 15 supporting the movable platen 14 movably is connected integrally to the movable platen 14 to which the movable mold 17 is fitted on the opposite side to the movable mold 17 fitting side, and the auxiliary platen 13 and the movable platen 14 are moved integrally while being guided by the tie-bars 15. Between the auxiliary board 13 and the movable platen 14, an ejector member 78 having an ejector pin 80 is arranged to be movable toward/from the movable platen 14 and to generate the ejection of the ejector pin 80 associated with approach to the movable platen 14, and a ball screw nut 88 fitted to the shaft 96 is fixed to the ejector member 78.

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, and more particularly to a mold having an ejector mechanism for ejecting and releasing a molded product held by a movable mold that provides one of a molding die for molding a predetermined molded product. The present invention relates to an improved structure of a fastening device.

[0002]

2. Description of the Related Art Generally, a mold clamping device used in a molding machine such as an injection molding machine or a press molding machine includes a fixed mold and a movable mold attached to a fixed plate and a movable plate, respectively, which are opposed to each other. Along with the original mechanism of the mold clamping device that opens and closes the mold and clamps the mold, the molded product molded in the molding die composed of the fixed mold and the movable mold is opened after the mold is opened.
An ejector mechanism that protrudes from the movable mold and is taken out is provided.

This ejector mechanism usually has a plate-shaped ejector member provided on the opposite side of the movable plate from the fixed plate side so as to be able to approach / separate from the movable plate, and a movable plate from the ejector member. An ejector pin that penetrates the board and extends toward the fixed board.
By the ejecting action of the ejector pin accompanying the approach movement of the ejector member with respect to the movable plate, a molded product formed in a molding die disposed between the movable plate and the fixed plate is protruded from the movable die side and separated. Is configured to obtain.

As a mold clamping device provided with such an ejector mechanism, for example, one having a structure disclosed in Japanese Utility Model Publication No. 2-2578 is known. That is, in this mold clamping device, a ball screw shaft extending in a direction parallel to the moving direction of the ejector member is rotatable around a central axis with respect to a back surface of the movable plate opposite to the fixed plate. In such a state, a servomotor for rotating and driving the ball screw shaft is attached while being fixed in position. The ejector member is provided with a ball screw nut screwed onto the ball screw shaft so as to be non-rotatable and fixed in position. With the rotation of the ball screw shaft driven by the servo motor, The ejector member is moved in the direction of the center axis of the ball screw shaft so as to be moved closer to / separated from the movable platen. Therefore, in such a mold clamping device, the ejection stroke of the ejector pin can be easily controlled by the drive control of the servomotor, and the ejector member is moved to the movable plate by using, for example, a hydraulic cylinder. Several advantages are obtained, such as the fact that the ejector mechanism and, consequently, the entire mold clamping device can be configured with a simple structure, as compared with the structure that can be moved closer.

However, in such a conventional mold clamping device, a ball screw shaft and a servomotor are directly attached to the back of a movable plate, and an ejector pin and a ball screw nut are fixed. That the ejector member is attached via the ball screw shaft, the weight on the back side of the movable plate becomes larger than the weight on the surface facing the fixed plate to which the movable die is attached. Was inevitable. For this reason, among the mold clamping devices having such a structure, in particular, the movable plate is movably supported by a plurality of tie bars extending horizontally from the fixed plate, and is guided by the plurality of tie bar members to fix the movable plate. In the structure configured to be able to move toward / separate from the board, the existence of the clearance formed in the supporting portion of each movable board by each tie bar,
The movable plate is inevitably inclined to the back side, which makes it difficult to maintain the parallelism between the movable plate and the fixed plate on the mutually facing surfaces. As a result, the movable plate and the fixed plate are fixed. There was a risk that a molded product having a desired shape and dimensions could not be obtained due to insufficient clamping of a molding die composed of a movable die and a fixed die attached to the board.

In addition, in such a mold clamping device, the ball screw shaft which causes the ejector pin to protrude by moving the ejector member close to the movable platen has a problem.
From the place fixed to the movable platen,
It is expected that a similar problem as described above may be caused due to the ejecting action of the ejector pin, in other words, the operation of the ejector mechanism.

That is, for example, in an injection molding machine, after injection molding of a molten resin into a molding cavity, the molten resin in the molding cavity is partially compressed in order to prevent the occurrence of sink marks in a molded product. In some cases, the gate is cut by the ejecting action of the ejector pin (operation of the ejector mechanism) so that the ejector member may be disengaged if a mold clamping device as disclosed in the above publication is employed. The movable platen and the movable die attached thereto are deformed by being pressed by the ball screw shaft based on the reaction force against the ejecting force of the ejector pin transmitted to the ball screw shaft via the ball screw nut, and As a result, a deformation or a partial change in the thickness of the semi-solidified molded product is caused, and a desired shape and dimensions are not obtained in the finally obtained molded product. Than it is likely to disappear.

[0008]

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a movable plate having a plurality of tie bars extending horizontally from a fixed plate. In a mold clamping device configured to be movably supported and moved toward and away from the fixed plate while being guided by the plurality of tie bars,
After the mold is opened, a molded product molded in a molding die disposed between the movable platen and the fixed platen is ejected from one movable die constituting the molding die, and an ejector mechanism for detaching the molded product is arranged. The reduction in the parallelism between the movable platen and the fixed platen and the deformation of the movable platen and the molding die (movable die) attached thereto due to the installation and the operation of the ejector mechanism can be effectively prevented or suppressed. Accordingly, it is an object of the present invention to provide a structure capable of reliably and stably obtaining a molded product having a desired shape and size.

[0009]

According to the present invention, in order to solve the above-mentioned problem, a fixed plate fixed to a position to which the fixed mold is attached, among a fixed mold and a movable mold constituting a molding die,
A plurality of tie bars extending in a horizontal direction from the fixed plate, and the fixed die supported movably by the plurality of tie bars, and moved toward and away from the fixed plate while being guided by the plurality of tie bars. A movable plate to which the movable die is attached, and an ejector member disposed on the side of the movable plate opposite to the movable die attachment side so as to be able to approach / separate from the movable plate. An ejector pin extending from the ejector member to the fixed plate side through the movable plate, and the ejector pin is held by the movable mold by a protruding action of the ejector pin as the ejector member moves closer to the movable plate. In a mold clamping device configured to protrude a molded product, the ejector member is sandwiched between the movable platen and the movable mold mounting side, and the ejector member is moved. An auxiliary board facing the movable board is movably supported by the plurality of tie bars, and further connected to the movable board, and the auxiliary board and the movable board, While being configured to be integrally moved while being guided by the plurality of tie bars, a ball screw shaft extending parallel to the moving direction of the ejector member can be rotated around the center axis with respect to the auxiliary plate. In addition to providing a fixed position in the state, a driving means for rotating the ball screw shaft is attached, and further, a ball screw nut screwed into the ball screw shaft,
By providing the position fixed to the ejector member in a non-rotatable state, with the rotation of the ball screw shaft,
The invention is characterized in that the ejector member is moved in the direction of the center axis of the ball screw shaft so that the ejector member can be moved closer to the movable platen. .

In such a mold clamping device according to the present invention, a plurality of auxiliary plates, which are opposed to such a movable plate at a predetermined interval, are provided on the opposite side of the movable plate from the movable die mounting side. While being movably supported by the tie bar, the movable platen is connected to the auxiliary plate and the movable plate,
The movable platen is supported not only by its own tie bar support region but also by the auxiliary plate tie bar support region, as it can be moved integrally while being guided by a plurality of tie bars. Accordingly, the length of the supporting portion for each tie bar of the movable plate is substantially extended in the length direction of each tie bar as compared with the case where the movable plate is movably supported by a plurality of tie bars alone. Can be obtained.

Therefore, in such a mold clamping device, a molded product formed in a molding die disposed between the movable platen and the fixed platen is moved from the movable die attached to the movable platen after the mold is opened. An ejector pin and an ejector member that constitute an ejector mechanism that protrudes and detaches are attached to the back surface of the movable platen opposite to the movable-type attachment side, and the weight of the movable platen on the back side is reduced by the movable-type attachment surface. Despite being larger than the weight on the side, the tilt to the back side due to the clearance formed at the support part of the movable plate by each tie bar allows the movable plate to move independently with multiple tie bars It can be advantageously made smaller compared to supported conventional devices,
The parallelism of the movable platen and the fixed platen on the mutually facing surfaces can be maintained extremely stably.

Further, in the mold clamping device according to the present invention, the ball screw shaft for projecting the ejector pins is attached to the auxiliary plate by moving the ejector member closer to the movable plate. For example, when performing gate cutting by the ejecting action of the ejector pin (operation of the ejector mechanism),
The reaction force to the ejector pin protrusion force transmitted to the ball screw shaft will be exerted on the auxiliary plate,
Thus, unlike the conventional device in which the ball screw shaft is attached to the movable plate, the movable plate and the molding die (movable die) attached to the movable plate are further attached to the ball screw shaft by the reaction force against the projecting force of the ejector pin. This can be advantageously prevented from being pressed and deformed.

Therefore, in such a mold clamping device according to the present invention, the parallelism between the movable platen and the fixed platen by disposing the ejector mechanism on the surface of the movable platen opposite to the movable platen mounting surface side. Of the movable platen and the molding die (movable die) attached to the movable platen due to the operation of the ejector mechanism can be effectively prevented. The molded article having the shape and dimensions can be obtained very reliably and stably.

According to one preferred embodiment of the mold clamping device according to the present invention, the auxiliary plate is detachably connected to the movable plate, and the ball screw nut is connected to the ejector member. Removably attached to

In the mold clamping device having such a configuration, the auxiliary plate and the movable plate are uncoupled from each other simply by removing the auxiliary plate from the movable plate and removing the ball screw nut from the ejector member. Can do
This makes it possible to easily and quickly move the auxiliary board away from the movable board.

Accordingly, in such a mold clamping device, for example, a transmission member such as a belt or a chain is bridged between the output shaft (drive shaft) of the driving means and the ball screw shaft, and this transmission member In a case where the driving force of the driving means is configured to be transmitted to the ball screw shaft, such a transmission member is
Even if it is positioned between the opposing surfaces of the auxiliary plate and the movable plate, as described above, if the integrated connection state of the auxiliary plate and the movable plate is released and the auxiliary plate is moved away from the movable plate, The advantage is obtained that the transmission member can be easily and quickly removed and replaced from the output shaft of the drive means and the ball screw shaft without being disturbed by the movable platen.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, in order to clarify the present invention more specifically, representative embodiments of the present invention will be described.
This will be described in detail with reference to the drawings.

First, FIG. 1 schematically shows a main part of a mold clamping device in an injection molding machine as one embodiment of the present invention in a longitudinal sectional form. As is clear from FIG. 1, the mold clamping device includes a mold opening / closing cylinder 12 supported by a base 10 and movable in an axial direction extending in a horizontal direction. At the front end in the direction, the movable plate 1
4 is fixed. And the mold opening / closing cylinder 12
By being reciprocally driven in the axial direction by the ball screw mechanism, the movable platen 14 is reciprocated in a horizontal approaching or distant direction with respect to a fixed plate (not shown) arranged opposite thereto, whereby: The movable mold 17 attached to the movable board 14 and the fixed mold (not shown) attached to the fixed board are configured to be closed or opened, and fixed to the movable mold 17. When the mold is closed, the mold opening / closing cylinder 12 is further moved forward by a predetermined hydraulic mechanism.
The mold clamping force is exerted against the. Furthermore,
Here, the movable platen 14 includes a plurality of (here, four) tie bars 15 protruding from the fixed platen similarly to the conventional device.
With this, it is structured to be guided in the horizontal direction. In the following description, with reference to the moving direction of the movable platen 14, the left side in FIG. 1 is referred to as a retreating side, and the right side in FIG.

More specifically, the mold clamping device of the present embodiment
A mold opening / closing ball screw shaft 18 extending in the horizontal direction is provided. The mold opening / closing ball screw shaft 18 is supported by a bracket 16 erected on the base 10 via a bearing at an axially retracted end (left end in FIG. 1). , So as to be rotatable about the central axis and immovable in the axial direction. In addition, the ball screw shaft 18 for opening and closing the mold projects from a position supported by the bracket 16 with a sufficient length toward the axially forward side (the right side in FIG. 1).
An end of the mold opening / closing ball screw shaft 18 on the bracket 16 support side projects from the bracket 16 by a predetermined length, and a toothed pulley 20 is attached thereto. On the other hand, a mold opening / closing servomotor 22 is fixed to the bracket 16 supporting the mold opening / closing ball screw shaft 18, and a toothed pulley 24 is attached to an output shaft of the mold opening / closing servomotor 22.
Is attached. A toothed belt 25 is stretched between the toothed pulley 24 of the mold opening / closing servomotor 22 and the toothed pulley 20 attached to the mold opening / closing ball screw shaft 18. The mold opening / closing ball screw shaft 18 is rotatably driven by a mold opening / closing servomotor 22 via a belt 25.

In the ball screw shaft 18 for opening and closing the mold, a mold opening / closing cylinder 12 having a substantially cylindrical shape as a whole is externally inserted into the projecting portion at a portion protruding from the bracket 16 toward the axially forward side. Being concentrically arranged. That is, this mold opening / closing cylinder 12
The die opening / closing ball screw shaft 18 is spaced radially outward to extend over the outer peripheral surface of the protruding portion of the die opening / closing ball screw shaft 18, and on the same central axis as the die opening / closing ball screw shaft 18. Therefore, it is extrapolated so as to be relatively displaceable in the axial direction with respect to the mold opening / closing ball screw shaft 18.

The movable platen 14 is fixedly mounted on the end face of the mold opening / closing cylinder 12 on the axially forward side via an auxiliary plate 13 integrally connected thereto. A mold opening / closing ball screw nut 26 screwed to the mold opening / closing ball screw shaft 18 is fixed to the axially retracted end portion of the nut 12 by a screw (not shown) or the like. As a result, the movable platen 14 is positioned so as to be integrally movable with the mold opening / closing cylinder 12 on the tip end side of the mold opening / closing cylinder 12.
6 is supported by the mold opening / closing cylinder 12 so as not to move in the axial direction and to rotate around the central axis.

Thus, in this embodiment, the mold opening / closing ball screw shaft 18 is rotationally driven in the forward and reverse directions by the mold opening / closing servo motor 22 to thereby open and close the mold opening / closing ball screw shaft 18. The mold opening / closing cylinder 12 can be moved forward / backward in the axial direction based on the screw feed action of the ball screw nut 26 for use. By the movement, the movable board 14 is moved forward / backward together with the auxiliary board 13, so that the mold opening / closing operation can be performed.

In the axially intermediate portion of the mold opening / closing cylinder 12, a mold clamping cylinder member 28 fixedly supported by a bracket 30 erected on the base 10.
Are extrapolated and arranged radially outwardly. The mold clamping cylinder member 28 has a cylinder wall portion (having a large diameter) that expands toward the forward side (movable platen 14 side) of the mold opening / closing cylinder 12 as a whole, and its axially retracting side. A small-diameter seal flange 32 and a large-diameter seal flange 34 each having a cylindrical shape are fixedly provided on the axially forward side. The plurality of tie bars 15 that guide the movable platen 14 in the moving direction are also fixed to the bracket 30 that supports the mold clamping cylinder member 28 at their axially retracted ends.

Further, a mold clamping ram 36 is assembled to the mold clamping cylinder member 28 while being inserted therein. The mold clamping ram 36 is provided with the mold opening / closing cylinder 12.
It has a larger diameter than that of the mold opening / closing cylinder 12 and is arranged outside the mold opening / closing cylinder 12 so as not to interfere with the mold opening / closing cylinder 12. Further, the mold clamping ram 36 has a similar shape that is slightly smaller than the mold clamping cylinder member 28 and is provided on both sides in the axial direction of a ram wall 38 expanding toward the forward side of the mold opening / closing cylinder 12. The small-diameter cylindrical portion 40 and the large-diameter cylindrical portion 42 each having a cylindrical shape are integrally formed.

Then, under such an assembled state of the mold clamping ram 36 with respect to the mold clamping cylinder member 28, between the small-diameter cylindrical portion 40 of the mold clamping ram 36 and the small-diameter seal flange 32 of the mold clamping cylinder member 28, and The space between the large-diameter cylindrical portion 42 of the clamping ram 36 and the large-diameter seal flange 34 of the mold clamping cylinder member 28 is fluid-tightly sealed by a sealing member 44 extending continuously in the circumferential direction. The ram 36 is slidable with respect to the clamping cylinder member 28, so that a clamping cylinder chamber 46 extending continuously in the circumferential direction between the clamping ram 36 and the clamping cylinder member 28. Are formed. Further, the mold clamping cylinder chamber 46 is provided with a hydraulic unit 50 fixedly mounted on the outer peripheral portion of the mold clamping cylinder member 28 through a pressure oil flow hole 48 formed through the mold clamping cylinder member 28 in the thickness direction. It is connected to the.

Accordingly, here, the pressurized oil flows from the hydraulic unit 50 into the mold closing cylinder chamber 46 through the pressurized oil flow hole 48, and the hydraulic pressure is applied to the inside of the mold closing cylinder chamber 46. The clamping ram 36 is configured to be moved in the forward direction coaxially with the mold opening / closing cylinder 12 on the outer peripheral side of the mold opening / closing cylinder 12.

A locking mechanism 54 is mounted at the tip of the large-diameter cylindrical portion 42 of the mold clamping ram 36. The locking mechanism 54 has a pair of semi-cylindrical half nuts 56, 56 arranged radially opposite each other, and the pair of half nuts 56, 56 are fixed to the clamping ram 36. The mold housing ram 36 is supported by the guide housing 58 so as to be immovable in the axial direction and displaceable in the radially opposite direction. And
The pair of half nuts 56, 56 are reciprocally driven in the approach / separation direction with respect to the mold opening / closing cylinder 12, respectively, by the drive cylinder mechanisms 60, 60 fixed to the guide housing 58, respectively. I have.

Further, the pair of half nuts 56,
On the inner peripheral surface of 56 (the surface facing the outer peripheral surface of the mold opening / closing cylinder 12), a plurality of meshing teeth 62 continuously extending in the circumferential direction with a sawtooth cross section are provided at equal intervals in the axial direction. Is formed. In addition, each half nut 56,5
6 extends continuously in the circumferential direction on the outer peripheral surface of the mold opening / closing cylinder 12 where the inner peripheral surface is opposed to each other, with a saw-tooth cross section having a cross section corresponding to the meshing teeth 62 formed on each of the half nuts 56, 56. A large number of locking teeth 64 are formed at equal intervals in the axial direction. Note that the axial pitch (formation interval) of the meshing teeth 62 and the locking teeth 64 is the same,
In addition, both are provided at regular intervals in the axial direction.

Thus, in the present embodiment, the pair of half nuts 56, 56 are held at the retracted positions (positions separated radially outward from the mold opening / closing cylinder 12) by the drive cylinder mechanisms 60, 60. In the closed state, the mold clamping ram 36 is released from the mold opening / closing cylinder 12, and the mold opening / closing cylinder 12 can be freely moved in the axial direction without being limited by the mold clamping ram 36. It has become. Then, the mold opening / closing cylinder 12 is moved forward to some extent in the axial direction, and after the locking teeth 64 formed on the outer peripheral surface of the mold opening / closing cylinder 12 are positioned radially inward of the half nut 56, By driving the pair of half nuts 56, 56 to the protruding position (the position close to the mold opening / closing cylinder 12) by the drive cylinder mechanisms 60, 60, the mesh formed on the inner peripheral surfaces of the half nuts 56, 56, respectively. The teeth 62 are engaged with locking teeth 64 formed on the outer peripheral surface of the mold opening / closing cylinder 12, so that the mold clamping ram 36 is engaged with the locking mechanism 5.
4, it is locked so as not to be able to move relative to the mold opening / closing cylinder 12 in the axial direction and is integrated.

Therefore, in the mold clamping apparatus according to the present embodiment, the hydraulic pressure is applied to the mold clamping cylinder chamber 46 under the condition that the mold clamping ram 36 is locked to the mold opening / closing cylinder 12 by the locking mechanism 54 as described above. The mold clamping ram 36 and the mold opening / closing cylinder 1 are moved forward to move the mold clamping ram 36 forward.
2 are integrally moved in the forward direction, so that a mold clamping force is exerted on the movable plate 14 attached to the mold opening / closing cylinder 12 via the auxiliary plate 13.

Here, the ball screw shaft 1 for opening and closing the mold is used.
8, a ball screw shaft 53 for position adjustment,
It is disposed so as to be rotatable around the central axis and immovable in the axial direction with respect to a bracket (not shown) provided thereon, and a position adjustment servomotor 52 is mounted on the mold clamping cylinder member 28 by the mold clamping cylinder member 28. Supported. Further, the ball screw shaft 53 for position adjustment and the servo motor 52 for position adjustment
Are attached to the output shafts of the pulleys 57 and 59, respectively.
The toothed belt 61 is stretched between them, whereby the ball screw shaft 53 for position adjustment is driven to rotate by the servomotor 52 for position adjustment via the toothed belt 61. I have. Further, a ball screw nut 55 for position adjustment is screwed onto such a ball screw shaft 53 for position adjustment, and the ball screw nut 55 for position adjustment is connected to a small-diameter cylindrical portion of the mold clamping ram 36. With respect to the mounting bracket 63 screwed to the end face of 40,
It is fixed by screws or the like (not shown).

Thus, in this embodiment, the position adjusting ball screw shaft 53 is driven to rotate in the forward and reverse directions by the position adjusting servo motor 52, and the position adjusting ball screw shaft 53 is rotated.
The axial position of the clamping ram 36 can be adjusted by moving the clamping ram 36 forward / backward in the axial direction based on the screw feeding action of the position adjusting ball screw nut 55 screwed into the nut. It has become. Then, by the position adjustment of the mold clamping ram 36 by the position adjusting servo motor 52, the locking mechanism 54 attached to the mold clamping ram 36 is provided.
By controlling the relative position in the axial direction with respect to the mold opening / closing cylinder 12 so that the meshing teeth 62 of the half nuts 56, 56 and the locking teeth 64 of the mold opening / closing cylinder 12 are securely engaged, the locking mechanism is provided. The locking state of the mold clamping ram 36 with the mold opening / closing cylinder 12 by the mold 54 can always be stably ensured.

As described above, in the present embodiment, the movable plate 14 is attached to the tip of the mold opening / closing cylinder 12 via the auxiliary plate 13.
The auxiliary plate 13 interposed between the movable platen 14 and the mold opening / closing cylinder 12 has a rectangular flat plate shape as a whole, as is clear from FIGS. The mold opening / closing cylinder 12 is fixed at the front end surface at the center of the opposite surface.
In addition, in the auxiliary board 13, a tie bar insertion hole 66 penetrates in each of the four corners in the thickness direction,
Is provided. And these four tie bar insertion holes 6
6, spacer bushings 68 are respectively inserted and fixed, and in the inner holes of these spacer bushings 68,
The four tie bars 15 extending in the horizontal direction from a fixed plate (not shown) are inserted with a slight clearance. Thus, the auxiliary board 13 is slidably supported on each tie bar 15 (see FIG. 4).

On the other hand, as shown in FIGS. 1 and 3, the movable plate 14 also has a substantially rectangular flat plate shape having substantially the same size as the auxiliary plate 13. The cylindrical projections 70 each having an inner hole penetrating in the direction are integrally formed so as to project toward one side in the plate thickness direction. And, in the inner holes of these four cylindrical projections 70,
Two spacer bushes 72, 72 are respectively inserted and fixed.
The four tie bars 15 are respectively inserted through the inner holes with a small clearance. Thus, the movable platen 14 is slidably supported by the tie bars 15 similarly to the auxiliary plate 13 (see FIG. 4).

In such a movable board 14,
The four mounting protrusions 74 extending horizontally at a predetermined height are provided on the surface on the formation side of the four cylindrical protrusions 70, and the four cylindrical protrusions 7.
0, each of which is integrally protruded. As is clear from FIGS. 2 and 4, the movable plate 14 is attached to a fixed plate (not shown) on the surface opposite to the side on which the four mounting protrusions 74 are formed (the mounting side of the movable die 17). On the other hand, on the surface on the side where the four mounting projections 74 are formed (on the side opposite to the mounting side of the movable die 17), the four mounting projections 74 are positioned opposite to the auxiliary plate 13, and At the tips of the four mounting projections 74, the four mounting projections 74 are fixed to the auxiliary board 13 by mounting bolts 76.

Thus, the movable board 14 and the auxiliary board 13 are
Under the condition that both are slidably supported by the four tie bars 15, they are integrally arranged while being opposed to each other with an interval corresponding to the axial length of the four mounting protrusions 74. Are linked together. And, thereby, the movable platen 14 is provided with the four cylindrical projections 7 provided thereon.
In addition to the four tie bars 15, the four tie bar insertion holes 66 serving as support portions for the tie bars 15 of the auxiliary board 13 can be slidably supported by the tie bars 15, and as described above. The mold opening / closing cylinder 12 is fixed to the surface of the auxiliary plate 13 connected to the movable plate 14 on the side opposite to the movable plate 14 side, so that the movable plate 14 and the auxiliary plate 13 are fixed. With the forward / backward movement of the mold opening / closing cylinder 12,
While being guided by the book tie bar 15, it can be integrally moved toward and away from a fixed plate (not shown).

As is clear from FIGS. 1 and 3, in this embodiment, an ejector plate 78 as an ejector member is disposed between the movable plate 14 and the auxiliary plate 13 in particular. Have been. The ejector plate 78 is generally composed of a cross-shaped flat plate that is smaller than the movable platen 14 and extends vertically and horizontally, and has a cross-shaped central portion on one surface thereof, Elongated rod-shaped ejector pins 80 each having a predetermined length are erected one by one at a total of five intermediate portions with the four end portions so as to extend in the horizontal direction. Here, the ejector pin 80 is composed of two divided bodies, a base divided body 82 and a distal divided body 84 screwed into the base divided body 82.
At the end of the base-side divided body 82 opposite to the screw-in side of the distal-side divided body 84, the ejector plate 78 is screwed into the five places, thereby being detachably mounted on the ejector plate 78. It has become.

In the ejector plate 78 on which the ejector pins 80 are erected, of the four cross-shaped ends, the ejector pins 80 are arranged vertically (in the height direction of the ejector plate 78). Guide holes 85, 85 passing through the two ends in the thickness direction.
Are provided, and guide pins 86, which are shorter than the mounting projections 74, 74 of the movable plate 14, respectively.
86 is attached so as to extend in the horizontal direction while being slidably inserted into each guide hole 85. Further, the other two ends of the ejector plate 78 which are located side by side in the left-right direction (the width direction of the ejector plate 78) are provided with ejector ball screw nuts 88, 88, respectively. In the state where the screw holes are positioned so as to extend in the horizontal direction, the screw holes are provided so as to be non-rotatable and fixed in position by being bolted respectively (see FIG. 4).

Then, such an ejector plate 7
8 is arranged between the movable plate 14 and the auxiliary plate 13 such that the surface on the upright side of the ejector pin 80 faces the surface of the movable plate 14 facing the auxiliary plate 13, and Under such an arrangement, the five ejector pins 8 extending horizontally from the ejector plate 78 are provided.
0 are respectively inserted into and positioned in five through holes 90 provided in the movable platen 14, and extend horizontally from the ejector plate 78 in parallel with the five ejector pins 80. The two guide pins 86 to be protruded are screwed to the movable plate 14 at their distal ends and fixed respectively.

Thus, the ejector plate 78
Can be moved toward and away from the movable platen 14 in the horizontal direction while being guided by the two guide pins 86, 86, and the ejector plate 78 moves toward and away from the movable platen 14 in the horizontal direction. With
Each ejector pin 80 can be made to protrude into the movable mold 17 by a size corresponding to the amount of movement of the ejector plate 78.

It should be noted that here, the movable platen 14 and the auxiliary plate 13
The guide pins 86, 86 having a shorter length than the mounting projections 74, 74 are connected to the movable plate 14. Diameter regulating disks 94, 94 are screwed, respectively.
The separation of the ejector plate 78 from the movable plate 14 is restricted by the contact of the surface of the ejector plate 78 on the auxiliary plate 13 side. Thus, in the mold clamping device of the present embodiment, not only the approach movement of the ejector plate 78 to the movable plate 14 but also the separation movement thereof is not hindered by the auxiliary plate 13. An interval enough to allow the movement of the ejector plate 78 can be ensured between the surfaces facing the movable platen 14.

As is clear from FIGS. 3 and 4, between the auxiliary plate 13 on which the ejector plate 78 is disposed as described above and the movable plate 14, two ball screw shafts for ejector are provided. 96, 96 are further provided. The two ejector ball screw shafts 96, 96 are aligned in the width direction (the left-right direction in FIG. 3) at the same height position on the auxiliary plate 13 and the movable plate 14, and move from the auxiliary plate 13 to the movable plate 14. It is positioned so as to extend in the horizontal direction. In each of the ejector ball screw shafts 96, 96, the outer peripheral surface is a smooth surface.
At the smooth portion on one side in the length direction, the screw is provided on the outer peripheral surface while being inserted through the inner holes of the two cylindrical housings 98, 98 bolted to the auxiliary plate 13, respectively. At the thread forming portion on the other side in the length direction, the ejector plate 78 is screwed into the ejector ball screw nuts 88 attached to both ends of the ejector plate 78 in the width direction (left and right directions in FIG. 3). In the two through holes 100, 100 formed at both ends in the width direction of the movable plate 14 and penetrating the movable plate 14 in the thickness direction, and the inner peripheral surfaces thereof do not interfere with each other. And it is rushed.

The cylindrical portion of the cylindrical housing 98 into which the smooth portion of each of the ejector ball screw shafts 96 is inserted is projected radially inward to a predetermined height at an intermediate portion in the axial direction. An inward flange portion 102 extending continuously from the front end is integrally formed. Further, the mounting surface of the cylindrical housing 98 of the auxiliary panel 13 is located closer to the mounting surface of the auxiliary housing 13 than the portion where the inward flange portion 102 is formed in the inner hole.
A thick wall having an inner hole through which a smooth portion of the ejector ball screw shaft 96 can be inserted, and having an outer diameter larger than the inner diameter of the inward flange portion 102 and smaller than the diameter of the inner hole of the cylindrical housing 98. The locking member 104 made of an annular plate abuts on both end surfaces thereof the mounting surface of the cylindrical housing 98 in the auxiliary panel 13 and the surface of the inward flange portion 102 of the cylindrical housing 98 facing the mounting surface. In a locked state, it is arranged so as not to be movable and rotatable around the central axis. A plurality (three in this case) of bearings 106 are fixedly disposed on the movable platen 14 side of the inner hole of the cylindrical housing 98 with respect to the portion where the inward flange portion 102 is formed.

Then, such a cylindrical housing 98 is formed.
The locking member 104 is attached to the flat portion of each of the ejector ball screw shafts 96 inserted into the inner hole of the ejector by screwing so as to be integrally rotatable and fixed in position. But a plurality of bearings 106
Supported by With this configuration, each ejector ball screw shaft 96 is disposed between the auxiliary plate 13 and the movable plate 14 so as to extend in the horizontal direction, which is the direction in which the ejector plate 78 moves, with respect to the auxiliary plate 13. It is fixed so as to be rotatable about the central axis and immovable.

Further, in such two ball screw shafts 96 for ejectors, a cylindrical housing 98 is provided.
To be inserted into the inside and ball screw nut 8 for each ejector
The toothed pulleys 108, 108 are provided between the screwing portions of the ejector ball screw shafts 96, 96, that is, at the portions located between the auxiliary plate 13 and the ejector plate 78 on the respective ejector ball screw shafts 96, 96. , Is fixed,
At the lower end of the auxiliary board 13 to which the ejector ball screw shaft 96 is fixed, a toothed pulley 110 different from the toothed pulley 108 of the ejector ball screw shaft 96 is fixed to the output shaft. Ejector servo motor 112
Is attached. A toothed belt 114 is stretched between the toothed pulleys 108 and 108 of each ejector ball screw shaft 96 and the toothed pulley 110 of the ejector servo motor 112. , The two ejector ball screw shafts 96 are driven to rotate by the ejector servomotor 112 (see FIG. 1).

Thus, in the present embodiment, the two ejector ball screw shafts 96, 96 are rotationally driven in the forward and reverse directions by the ejector servo motor 112, whereby the respective ejector ball screw shafts 96, 96 are screwed. Two combined ball screw nuts for ejector 88, 8
8, the ejector plate 78, to which the two ejector ball screw nuts 88, 88 are fixed, is moved closer to / separated from the movable platen 14. As the ejector plate 78 moves closer to the movable platen 14,
Each ejector pin 80 attached to the ejector plate 78 can be made to protrude into the movable mold 17 by a size corresponding to the amount of movement of the ejector plate 78.

As is clear from this, in the present embodiment, the ejector servomotor 112, the ejector ball screw shafts 96, 96, the ejector ball screw nuts 88, 88, and the ejector plate 78
And the five ejector pins 80 constitute an ejector mechanism. The ejector ball motor shafts 96, 96 driven by the ejector servomotor 112 rotate to generate two ejector mechanisms. By moving the ejector plate 78 closer to the movable platen 14 based on the screw feed action of the two ejector ball screw nuts 88, 88, the ejecting action of each ejector pin 80 is caused. is there.

In particular, in the mold clamping device of this embodiment, two ejector ball screw nuts 8 are provided.
8, 88 and a plurality of ejector pins 80 are attached,
An ejector plate 78 configured to be moved toward and away from the movable platen 14 is provided on a surface of the movable platen 14 on the auxiliary platen 13 side, that is, a back surface opposite to the fixed platen to which the movable die 17 is attached. Although the weight on the back side of the movable plate 14 is larger than the weight on the surface facing the fixed plate, the movable plate 14 has four cylinders provided thereon as described above. Projection 70
In addition, the four tie bar insertion holes 66, which are support portions of the auxiliary board 13 for the tie bars 15, can be slidably supported on the tie bars 15, so that the movable board 14 The length of the support portion for each tie bar 15 is substantially extended in the length direction of each tie bar 15, so that each tie bar 15
The tilt of the movable platen 14 to the side opposite to the fixed plate, which is the heavier side, which is caused by the clearance formed in the support portion of the movable platen 14 to the movable platen 14, can be advantageously made small. The degree of parallelism between the and the fixed plate on the mutually facing surfaces can be maintained as much as possible.

By the way, when performing a predetermined injection molding using an injection molding machine having a mold clamping device having such a structure, the type of the resin material to be injected, the injection molding method to be adopted, and the like. Various operations will be performed in an appropriate order according to the following. For example, when performing injection molding using a thermoplastic resin material according to a general injection molding method, first, FIG. As shown in FIG.
The mold opening / closing servomotor 22 is rotated forward from the mold opening state of the molding mold (only the movable mold 17 is shown in FIG. 1) holding the mold 2 at the retracted position.
By rotating the mold 8, the mold opening / closing cylinder 12 is moved forward, and the movable platen 14 and the auxiliary platen 13 are guided by four tie bars 15 while being integrated with a fixed platen (not shown). , The mold closing operation of the molding die is performed. As described above, in the mold clamping device of the present embodiment, since the parallelism between the movable plate 14 and the fixed plate on the mutually facing surfaces can be maintained as much as possible, such a mold closing operation is performed. As a result, a sufficient mold closing state can always be obtained stably.

Subsequently, when the mold closing operation is completed, the drive cylinder mechanisms 60, 60 of the locking mechanism 54 are operated to drive the pair of half nuts 56, 56 to protrude. The meshing teeth 62, 62 are engaged with the engaging teeth 64 of the mold opening / closing cylinder 12, respectively. Thereafter, in such a locked state, the pressure oil flows from the hydraulic unit 50 into the mold clamping cylinder chamber 46 to apply hydraulic pressure to the mold clamping cylinder chamber 46 to move the mold clamping ram 36 forward. Then, the mold clamping ram 36 and the mold opening / closing cylinder 12 are integrally moved forward. Then, the movable platen 14 and the auxiliary platen 13 are moved further closer to the fixed platen, and the movable platen 14 is pressed against the fixed platen to perform a mold clamping operation.

Next, the molten resin is injected from the injection machine into the molding cavity of the molding die under the mold clamping state to fill the cavity. Thereafter, if necessary, a gate cut for preventing the occurrence of sink marks in the molded product is performed, and then the molten resin in the molding cavity is cooled and solidified to form a desired molded product.

In the gate cut during the above-described process, for example, the ejector plate 78 is moved close to the movable plate 14 by a predetermined distance in the same manner as in the prior art.
By causing each ejector pin 80 to protrude into the movable mold 17 by an amount corresponding to the amount of movement of the ejector plate 78, a gate cut pin provided on a gate cut plate (not shown) provided in the movable mold 17 is removed. This is performed by moving the movable mold 17 to perform gate cutting and simultaneously applying a predetermined compressive force to the molten resin in the molding cavity. At this time, a reaction force against the projecting force of each ejector pin 80 for moving the gate cut pin is applied to the ejector ball screw nut 88 via the ejector plate 78 to which the ejector pin 80 is attached and the ejector ball screw nut 88. Although transmitted to the shafts 96, 96, in the mold clamping device of the present embodiment, the ejector ball screw shafts 96, 96
, The reaction force against the projecting force of each ejector pin 80 is generated by the ejector ball screw shaft 9.
6, 96 will be exerted on the auxiliary board 13 to be attached. Therefore, when the in-mold gate cut is performed as described above, the movable plate 14 and further the movable mold 17 attached thereto have a pressing force based on a reaction force against the protruding force of the ejector pin 80, and the movable plate 14 is pressed against the ball screw shaft. It is possible to advantageously avoid being pressed and deformed.

Next, while maintaining the mutual locking state of the mold clamping ram 36 and the mold opening / closing cylinder 12 by the locking mechanism 54, the hydraulic oil in the mold clamping cylinder chamber 46 is discharged to the hydraulic unit 50 side. After the hydraulic pressure in the mold clamping cylinder chamber 46 is released, the mold opening / closing servomotor 22 is rotated in the reverse direction to move the movable plate 14 together with the auxiliary plate 13 at or near the position where the mold closing operation is completed. The pressure relief operation is performed by moving the actuator backward.

Thereafter, the drive cylinder mechanisms 60, 60 are operated, respectively, and the pair of half nuts 56, 56 are moved backward, so that the locking mechanism 54 allows the mold opening / closing cylinder 12 and the mold clamping ram 36 to communicate with each other. After releasing the locked state, the mold opening and closing servomotor 22 is again rotated in the reverse direction to move the movable plate 14 together with the auxiliary plate 13 to the position before performing the mold closing operation. Perform opening operation. At this time, the molded product molded in the molding cavity of the molding die should be held on the molding cavity surface 92 of the movable die 17.

When the mold opening operation is completed, the ejector servomotor 112 is rotated forward and the ejector ball screw shafts 96 are driven to rotate, thereby moving the ejector plate 78 closer to the movable platen 14 (see FIG. 4). When the gate cut is performed as described above, the ejector pins 80 attached to the ejector plate 78 are moved by a larger amount of movement than at that time. Is inserted into the movable mold 17 by a dimension corresponding to Then, in the same manner as in the related art, the ejector rod provided on the ejector plate (not shown) provided in the movable die 17 is formed on the molded product held in the movable die 17 by the projecting action of each ejector pin 80. The molded product is brought into contact with and moved, so that the molded product is protruded from the movable mold 17 and the intended molded product is taken out.

As described above, in the mold clamping device of the present embodiment, the ejector plate 78 provided with a plurality of the ejector ball screw nuts 88 and the ejector pins 80 is different from the movable plate 14 on the movable mold 17 mounting side. The movable platen 14 is mounted on the opposite back surface, and the movable platen 14 is supported on each tie bar 15 in spite of the fact that the weight on the backside of the movable platen 14 is larger than the weight on the movable die 17 mounting surface side. The inclination of the movable platen 14 toward the rear side, which is heavy due to the clearance formed in the portion, can be advantageously reduced, and the parallelism between the movable platen 14 and the fixed platen on the mutually facing surfaces can be reduced. As much as possible, a sufficient mold closing state of the movable mold 17 and the fixed mold attached to the movable board 14 and the fixed board, respectively, is always obtained stably.

Therefore, by using such a mold clamping device according to the present embodiment, a desired shape corresponding to the shape of the molding cavity in the molding die disposed between the movable platen 14 and the fixed platen. Thus, it is possible to reliably and stably obtain a molded product having the following shape and dimensions.

Further, in such a mold clamping device, it is possible to advantageously avoid deformation of the movable platen 14 and the movable mold 17 when performing gate cutting by the ejecting action of each ejector pin 80. From this point, it is possible to effectively prevent a change in the shape and thickness of the semi-solidified molded product in the molding cavity due to the projecting action of each ejector pin 80.

Therefore, in the mold clamping device of the present embodiment, unlike the conventional device, it is possible to advantageously completely eliminate the occurrence of molding defects due to the ejecting action of the ejector pins 80. Thus, the desired molded product can be obtained reliably and stably with a desired shape and size.

Further, in the mold clamping device of the present embodiment,
The auxiliary board 13 is connected to the movable board 14 by being bolted to the four mounting projections 74 of the movable board 14, and has ejector ball screw nuts 88 and 8.
8 is also fixed to the ejector plate 78 by bolts, so that the ejector plate 78 is
4, without removing the movable plate 1 of the auxiliary plate 13
4 and the bolt fixation of the ejector ball screw nuts 88 and 88 to the ejector plate 78, respectively, only by releasing the connection state of the auxiliary plate 13 to the movable plate 14 and moving the auxiliary plate 13 The ejector ball screw shafts 96, 96 can be separated from the board 14 by the ejector ball screw nuts 88, 96.
It can be done easily and quickly while screwed into 88.

Therefore, in such a mold clamping device,
Between the auxiliary plate 13 and the movable plate 14, the toothed belt 114 wrapped around the toothed pulleys 108, 108 of the ejector ball screw shafts 96, 96 and the toothed pulley 110 of the ejector servomotor 112, There is also an advantage that the work of removing and replacing the pulleys 108 and 110 from the toothed pulleys 108 and 110 can be performed very easily and quickly without being obstructed by the auxiliary plate 13 and the movable plate 14. is there.

Although the typical embodiments of the present invention have been described in detail above, they are merely examples, and the present invention is construed as being limited to such embodiments. It should be understood that it is not.

For example, in the above-described embodiment, the mold opening / closing operation is performed by the ball screw mechanism, while the mold clamping operation is performed by the hydraulic mechanism. The mold clamping operation is performed by a ball screw mechanism, or both the mold opening and closing and the mold clamping operation are performed by only one of a ball screw mechanism and a hydraulic mechanism. Further, the mold opening / closing operation and the mold clamping operation can be performed by an operating mechanism other than the ball screw mechanism and the hydraulic mechanism, such as a link mechanism.
It is possible.

The specific structures of the ball screw mechanism and the hydraulic mechanism for performing the mold opening / closing operation and the mold clamping operation are of course not limited to those shown in the above embodiment.

Further, in the above embodiment, the auxiliary board 13
Are connected to the movable platen 14 by being bolted to four mounting projections 74 integrally formed on the movable platen 14, but the connection structure of the auxiliary platen 13 to the movable platen 14 is also particularly limited. However, the auxiliary plate 13 and the movable platen are spaced apart from each other by allowing the ejector plate 78 positioned between the auxiliary plate 13 and the movable plate 14 to move toward and away from the movable plate 14. 14
Any structure can be adopted as long as the structure is integrally connected to enable the unit to move integrally.

Further, in the above embodiment, the two ejector ball screw shafts 96, 96 are rotatable about the central axis with respect to the two cylindrical housings 98, 98 fixed to the auxiliary plate 13. The number of such ejector ball screw shafts 96, 96 is limited by the number of ejector plates 78 serving as ejector members.
The ejector ball screw shaft 96 can be mounted on the auxiliary plate 13 directly and rotatably about the central axis and immovably, depending on the shape and size of the ejector. May be.

Further, the number of the ejector ball screw nuts 88 screwed to the ejector ball screw shaft 96 can be appropriately changed according to the number of the ejector ball screw shafts 96 provided. Also, the mounting structure of the ejector ball screw nut 88 to the ejector plate 78 as the ejector member is not limited to the one shown in the above-described embodiment as long as it can be fixedly mounted on the ejector plate 78. Needless to say, it is not.

Further, in the above embodiment, each of the ejector ball screw shafts 96 and the ejector servomotors 112 are provided.
Toothed pulleys 108 and 110 are fixedly mounted on the output shafts, respectively, and the driving force of the ejector servomotor 112 is transmitted through a toothed belt 114 stretched between the toothed pulleys 108 and 110. The mechanism for transmitting the driving force of the ejector servomotor 112 to each of the ejector ball screw shafts 96 is, for example, a toothed belt 114 such as a chain. The transmission mechanism using a transmission member other than the above, a gear transmission mechanism, or the like may be used.

In the above-described embodiment, the ejector plate 78 serving as an ejector member is fixed at one end to the movable platen 14, and is slidably attached to the ejector plate 78 at the other end.
The ejector plate 78 is supported by the guide plate 6 and moved toward and away from the movable plate 14 while being guided by the guide pins 86, 86.
Of each tie bar 15 in the same manner as the movable plate 14 and the auxiliary plate 13.
Each tie bar 15
It is also possible to be configured to be able to be moved while being guided by.

Further, in the above-described embodiment, the drive means for rotating the ejector ball screw shaft 96 is constituted by the ejector servomotor 112. However, other known drive means may be used. But,
It can be adopted.

In addition, in the above-described embodiment, a specific example in which the present invention is applied to a mold clamping device incorporated in an injection molding machine has been described. However, the present invention is applicable to various other press molding machines. Of course, the present invention can be advantageously applied to a mold clamping device or the like to be incorporated.

In addition, although not enumerated one by one, the present invention
Based on the knowledge of those skilled in the art, various changes, modifications, improvements, and the like can be made, and any of such embodiments can be implemented without departing from the spirit of the present invention. It goes without saying that they are included in the scope of the invention.

[0073]

As is apparent from the above description, in the mold clamping device according to the present invention, the movable platen and the fixed platen are provided by disposing the ejector mechanism on the surface of the movable platen opposite to the fixed platen. Can be advantageously eliminated or suppressed, and the deformation of the movable platen and the molding die attached thereto due to the operation of the ejector mechanism can be effectively prevented. As a result, Thus, a molded product having a desired shape and size can be obtained very reliably and stably.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view of an essential part showing an example of a mold clamping device according to the present invention, and shows a cross-sectional form taken along a line II in FIG.

FIG. 2 is an explanatory sectional view taken along the line II-II in FIG.

FIG. 3 is an explanatory sectional view taken along the line III-III in FIG. 1;

FIG. 4 is an explanatory sectional view taken along the line IV-IV in FIG. 3;

[Explanation of symbols]

12 mold opening / closing cylinder 13 auxiliary board 14 movable board 15 tie bar 17 movable type 18 mold opening / closing ball screw shaft 22 mold opening / closing servo motor 26 mold opening / closing ball screw nut 28 mold clamping cylinder member 36 mold clamping ram 74 mounting projection 78 ejector plate 80 Ejector pin 86 Guide pin 88 Ball screw nut for ejector 96 Ball screw shaft for ejector 112 Servo motor for ejector

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B30B 15/32 B30B 15/32 (72) Inventor Yuzumi Sugie 2nd radish, Kitazakicho, Obu City, Aichi Prefecture Co., Ltd. F-term (for reference) 4E090 HA07 4F202 CA11 CB01 CL12 CL22 CL39 CL43 CL48 CM02 CM90

Claims (2)

[Claims] 1. A fixed platen of a fixed position to which the fixed die is attached, among a fixed die and a movable die constituting a molding die,
A plurality of tie bars extending in a horizontal direction from the fixed plate, and the fixed die supported movably by the plurality of tie bars, and moved toward and away from the fixed plate while being guided by the plurality of tie bars. A movable plate to which the movable die is attached, and an ejector member disposed on the side of the movable plate opposite to the movable die attachment side so as to be able to approach / separate from the movable plate. An ejector pin extending from the ejector member to the fixed plate side through the movable plate, and the ejector pin is held by the movable mold by a protruding action of the ejector pin as the ejector member moves closer to the movable plate. In a mold clamping device configured to protrude a molded product, the ejector member is sandwiched between the movable platen and the movable mold mounting side, and the ejector member is moved. At an interval allowing the movement, the auxiliary plate facing the movable plate is movably supported by the plurality of tie bars, and further connected to the movable plate, and the auxiliary plate and the movable plate are While being configured to be integrally moved while being guided by the plurality of tie bars, a ball screw shaft extending parallel to the moving direction of the ejector member can be rotated around the center axis with respect to the auxiliary plate. The ball screw shaft is provided with a driving means for rotationally driving the ball screw shaft, and a ball screw nut screwed to the ball screw shaft is fixed to the ejector member in a non-rotatable state. By providing the position fixing, the ejector member is moved in the direction of the center axis of the ball screw shaft with the rotation of the ball screw shaft, and approaches the movable platen. Mold clamping apparatus characterized by being configured so as brought into motion. 2. The device according to claim 1, wherein the auxiliary plate is detachably connected to the movable plate, and the ball screw nut is detachably attached to the ejector member. Mold clamping device.