JP2002361700A - Mold clamping unit for injection molding machine and method for controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold clamping unit for an injection molding machine capable of accurately controlling a slightly opening position and a compression force (or a mold clamping force) of a mold even in an injection compression molding method which can release the mold or open the mold without problem even in the case of a deep molding and to provide a method for controlling the clamping unit. SOLUTION: The method for controlling the clamping unit comprises the steps of setting a stroke of a toggle mold clamping means of a composite mold clamping unit to a total value of a mold clamping stroke for generating a predetermined mold clamping force and a stroke of an initial mold opening step, closing the mold in a mold closing step from a mold opening limit to mold touching by a mold opening/closing means, subsequently mold clamping by the toggle mold clamping means, injecting, cooling, thereafter loosening the mold, and opening the mold in an initial mold opening step by the toggle mold clamping means, and then opening the mold in the mold opening step from a mold release maximum mold open position to a mold opening limit by the mold opening/closing means.

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 for an injection molding machine and a method for controlling the device, and more particularly, to a mold opening / closing means for opening and closing a mold mounted on a movable platen, and a mold for the mold. The present invention relates to a compound mold clamping device having a toggle mold clamping means for applying a clamping force, and a method of controlling the device.

[0002]

2. Description of the Related Art Conventionally, as this type of mold clamping device, for example, there is one disclosed in Japanese Patent Application Laid-Open No. 2000-280308, which will be described with reference to FIGS. The upper half of FIG. 3 shows the mold open state, and the lower half shows the mold clamped state.

As shown in FIG. 3, the movable platen 2 is moved together with the tie bar 3 and the end plate 6 with respect to the fixed platen 1 to open and close a mold (core type) 4 a attached to the movable platen 2. Connecting means 7 for fixing the tie bar 3 and integrally connecting the end plate 6 to the fixed platen 1
The mold (core mold) 4a provided between the movable platen 2 and the end plate 6 and closed by the mold opening / closing means 5 and the mold (cavity mold) 4b attached to the fixed platen 1 Toggle type clamping means 8 for clamping the mold by pressing
And a mold thickness adjusting means 9 for integrally adjusting the positions of the movable platen 2, the end plate 6 and the toggle-type mold clamping means 8 according to the thickness of the mold 4 to be used. After the mold 2 is moved to close the mold 4a, the mold 4 is clamped by the toggle mold clamping device 8. In addition, the mold clamping stroke of the toggle mold clamping means 8 is set to the elongation of the tie bar 3 for generating a predetermined mold clamping force (generally about several mm depending on the mold clamping force).

Next, the operation will be described.

As shown in FIGS. 3 and 4, the mold opening / closing means 5 is driven in the mold closing direction from the mold opening limit to be attached to the end plate 6, the tie bar 3, the movable platen 2, and the movable platen 2. When the mold 4a is closed and the mold is brought into a touch state, the joining means 7 operates in the joining direction, and the fixed platen 1,
The tie bar 3 and the end plate 6 are integrally joined. Next, by driving the toggle-type mold clamping means 8 in the mold clamping direction, the mold 4a is pressed against the mold 4b via the movable platen 2 to clamp the mold.

When the injection and cooling are completed, the toggle mold clamping means 8
Is driven in the mold loosening direction to loosen the mold to the mold touch position,
The connecting means 7 operates in the opening direction to separate the tie bar 3 and the end plate 6 from the fixed platen 1.
Is driven in the mold opening direction, and the end plate 6, the tie bar 3,
The movable platen 2 and the mold 4a attached to the movable platen 2 move to the mold opening limit in the mold opening direction to open the mold.

[0007]

In the conventional mold clamping device, a mold closing process from a mold opening limit to a mold touch is performed by a mold opening / closing means, and subsequently, the mold is clamped by a toggle-type mold clamping means, and injection, Since the mold is loosened after cooling, and the mold opening process from the mold touch to the mold opening limit is performed again by the mold opening / closing means, there are the following problems. (A) The driving force of the mold opening / closing means is determined in consideration of the weight of the driven object such as a movable platen and an ejector device, sliding resistance, acceleration during operation, and the like. The mold release of the molded product is not completed only by the mold loosening process, but may reach the position where the mold is opened by 5 to 20 mm from the touch of the mold. Above that, a defect that cannot be released occurs. When the maximum mold clamping force is 100, the required driving force of the mold opening / closing means is 1-2,
It is said that the required mold opening force (position at which the mold is opened by 5 mm) is 8 to 10. (B) If the driving force of the mold opening / closing means is increased so that a deep molded product can be surely released, the product cost of the mold opening / closing means increases. (C) In the injection compression molding method in which injection is performed with the mold opened in a small amount and subsequently compressed, the injection force is received by the mold opening / closing means, and the driving force of the mold opening / closing means loses the ejection force. The mold is slightly open (the mold is slightly open)
Can not control. In addition, the compression from the slightly opened state to the touch of the mold is also performed by the mold opening / closing means. Since the compression force depends on the driving force of the means, the compression force cannot be increased and is not practical.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is possible to release and open a mold without any problem even in a deep molded product. An object of the present invention is to provide a mold clamping device of an injection molding machine that can control a compression force (or a mold clamping force) with high accuracy, and a control method of the device.

[0009]

According to the present invention, the stroke of the toggle-type mold clamping means of the composite mold clamping device is defined as a mold-clamping stroke for generating a predetermined mold-clamping force and a stroke of the initial mold-opening process. The distance from the mold touch to the maximum mold opening position) is the total value, and the mold closing process from the mold opening limit to the mold touch is closed with the mold opening / closing means, and then the mold is closed with the toggle mold clamping means. After the injection and cooling, the mold is released by the toggle-type mold clamping means, and the mold is released from the mold release, and the initial mold opening process up to the mold release maximum position. The mold opening step is performed by the mold opening / closing means. As a result, the mold opening force in the initial mold opening step exceeds the required mold release force of the molded product, so that even a deep molded product can be released and opened without any problem.

Further, the mold closing process from the mold opening limit to immediately before touching the mold is closed by the mold opening / closing means, then the mold is closed by the toggle-type mold clamping means, and the mold is clamped, whereby the movable platen is moved to the mold. Advanced injection compression molding methods, such as injection in a state controlled to the position immediately before touch and then multi-stage compression control, are possible.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A composite mold clamping device according to the present invention comprises:
The stroke of the toggle-type mold-clamping means is the sum of the mold-clamping stroke for generating a predetermined mold-clamping force and the stroke in the initial mold-opening step from the touch of the mold to the maximum mold-opening position.

In a method of controlling a mold clamping device according to the present invention, a mold closing process from a mold opening limit to a mold touch is closed by a mold opening / closing means using the above mold clamping apparatus, and subsequently, a toggle-type mold clamping means is used. The mold is clamped, injection and cooling are performed, then the mold is released and the initial mold opening process is opened with the toggle mold clamping means, and then the mold is opened from the maximum mold release position to the mold opening limit. The process is performed by a mold opening / closing means.

With the above construction, the deep molded product in the mold cavity is gradually released from the mold by loosening the mold by the toggle-type mold clamping device and opening the mold in the initial mold opening step. It is ejected by the ejector device at the mold opening limit. The mold opening force generated when the mold is opened by the toggle-type mold clamping means gradually decreases as the mold is opened due to the toggle characteristics. However, the required mold release force of the molded product is advantageously reduced as the peeling proceeds.

Another method of controlling a mold clamping device according to the present invention is as follows.
In the mold closing process from the mold opening limit to the position immediately before the mold touch, the mold is closed by the mold opening / closing means, then the mold is closed by the toggle-type mold clamping means, the mold is clamped, and injection and cooling are performed. First, the mold opening process is opened by a toggle mold clamping means, and then the mold opening process from the maximum mold release position to the mold opening limit is performed by the mold opening / closing means. The position immediately before touching the mold is changed within the range of the stroke in the initial mold opening step of the toggle mold clamping means.

According to the above configuration, it is possible to cope with an injection compression molding method in which injection is performed in a slightly opened state and then compression is performed.
In such an injection compression molding method as well, although the injection force is received by the toggle-type mold clamping means, the driving force of the toggle-type mold clamping means is not inferior to the injection force. Clamping force) can be controlled with high precision.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A mold clamping apparatus according to an embodiment of the present invention will be described with reference to FIGS. The upper half of FIG.
The lower half shows the mold clamping state.

As shown in FIG. 1, a fixed platen 1 is fixed on a bed, and a movable platen 2 and an end plate 6 are axially mounted on a tie bar 3 slidably mounted at four corners of the movable platen 2. It is movably supported.

The fixed platen 1 has insertion holes for the tie bars 3 at four corners, and the tie bars 3 inserted into the insertion holes and the fixed platen 1 are connected or separated at predetermined positions in the axial direction outside the insertion holes. A coupling means 7 is provided, and a mold (cavity mold) 4b is attached to a surface on the movable platen 2 side.

A mold (core mold) 4a is mounted on the surface of the movable platen 2 on the fixed platen 1 side, and an ejector device (not shown) is mounted on the surface on the end plate 6 side.

Nuts 9 are incorporated into the end plates 6 in the insertion holes of the tie bars 3, respectively, and the nuts 9 are synchronously rotated by a rotation driving device such as a motor (not shown).

The end of the tie bar 3 on the side of the fixed plate 1 has a groove which is fixed in the axial direction to the fixed plate 1 when the tie bar 3 is connected by the connecting means 7. A screw portion is formed. The screw portion is screwed into the nut 9, and when the nut 9 is rotated synchronously, the tie bar 3 moves in the axial direction. The end of each tie bar 3 is fixed by the connecting plate 10 so as not to rotate.

A toggle mechanism 8a of a toggle-type mold clamping means 8 is disposed between the movable platen 2 and the end plate 6, and the ends of a pair of driven links which are flexibly extended and contracted are connected to the movable platen 2 and the end plate. 6 is rotatably mounted. Since the mounting position of the toggle mechanism 8a is closer to the center of the movable platen 2 than the toggle mechanism described in the related art,
This is effective for the bending of the movable platen 2 in the case of a small mold 4 or the like.

At the center of the end plate 6, a toggle driving device 8b of the toggle-type mold clamping means 8 is incorporated. When a screw portion such as a ball screw is rotated by a servo motor (not shown), a belt, a pulley, or the like, a ball screw or the like is formed. The nut 8c screwed forward is moved forward or backward according to the rotation direction of the ball screw or the like. One end of a drive link is rotatably attached to the nut 8c, and the other end of the drive link is rotatably attached to the driven link. Thus, when the nut 8c moves forward, the toggle mechanism 8a extends and clamps the mold. Conversely, when the nut 8c moves backward, the toggle mechanism 8a
Is bent, the mold is loosened, and the mold is opened. The stroke of the toggle mechanism 8a is a total value of a mold clamping stroke for generating a predetermined mold clamping force and a stroke of an initial mold opening process.

At a diagonal position between the fixed platen 1 and the movable platen 2, a pair of mold opening / closing means 5 is attached.
In the separated state, the movable platen 2, the end plate 6, and the toggle-type mold clamping unit 8 can be moved with respect to the fixed platen 1 by the expansion and contraction operation of the mold opening and closing means 5.

Next, the operation of the mold clamping device will be described with reference to FIGS.

First, the movable platen 2, the end plate 6, the tie bar 3, and the mold 4 a attached to the movable platen 2 are driven by driving the mold opening / closing means in the mold closing direction from the mold opening limit (mold open state). When the mold is closed and the mold is touched, the coupling means 7 operates in the coupling direction, and the fixed platen 1 and the end plate 6 are integrally coupled via the tie bar 3. Next, when the toggle driving device 8b of the toggle-type mold clamping means 8 operates in the mold closing direction, the mold 4a is pressed via the movable plate 2 against the mold 4b attached to the fixed plate 1 to clamp the mold. .

By setting in advance the degree of bending of the toggle mechanism 8a when switching from the mold opening / closing means 5 to the toggle-type mold clamping means 8, the timing of this switching can be changed, and the mold touch position can be set. Alternatively, it can be at a position immediately before touching the mold. Thus, the movable platen 2 can be injected while being controlled by the toggle-type mold clamping means 8 to a position immediately before touching the mold, and compression (or mold-clamping) can be performed during or after the injection by a toggle-type injection compression molding.

When the injection and cooling are completed, the driving device 8b of the toggle-type mold clamping means 8 is driven in the mold opening direction, and the movable platen 2 and the mold 4a are loosened to the mold touch position. 2, and the mold 4a opens the initial mold opening process up to the maximum mold opening position.

Next, the connecting means 7 is operated in the separating direction to separate the fixed plate 1 from the tie bar 3 and the end plate 6, and then the mold opening / closing means 5 is driven in the mold opening direction to move the end plate 6 and the toggle. The mold closing means 8, the tie bar 3, the movable platen 2, and the mold 4a are opened up to the mold opening limit. Hereinafter, the above operation is repeated.

The adjustment of the mold thickness and the mold clamping force of the mold used in the mold clamping apparatus are performed as follows.

First, the toggle-type mold clamping means 8 drives the toggle driving device 8b to bend the driven link of the toggle mechanism 8a to a state corresponding to the set mold clamping force. Next, the nut 9 is rotated by a rotation drive device (not shown) such as a motor so that the tie bar 3 is moved relative to the end plate 6 so as to be located at a mold thickness position slightly larger than the thickness (mold thickness) of the mold 8 to be used. Move.

Next, the mold opening / closing means 5 is driven in the mold closing direction, and when the tie bar 5 has been inserted into the fixed platen 1, the joining means 7
Operates in the joining direction, and after the fixed platen 1 and the end plate 6 are integrally joined via the tie bar 3, the nut 9 is rotated in the mold closing direction, and the end plate 6, the toggle-type mold clamping means 8, and the movable The plate 2 and the mold 4a attached to the movable plate 2 are integrally moved in the mold closing direction, and when the mold 4a is pressed against the mold 4b and the mold touches, the rotation of the nut 9 is started. Stop. The above procedure completes the mold thickness adjustment and mold clamping force adjustment.

[0033]

As described above, the present invention is configured as described above, so that a deep molded product can be released and opened without any problem. In addition, the position of the movable plate and the compression force (or mold clamping force) can be adjusted with high precision even in advanced injection molding methods such as injecting the movable plate under control just before touching the mold, and then performing multi-stage compression control. Can control.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a mold clamping device of an injection molding machine according to one embodiment of the present invention.

FIG. 2 is an operation diagram showing the operation of the mold clamping device of the present invention.

FIG. 3 is a sectional view showing a mold clamping device of a conventional injection molding machine.

FIG. 4 is an operation diagram showing the operation of a conventional mold clamping device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed board 2 Movable board 3 Tie bar 4a Die (core type) 4b Die (cavity type) 5 Die opening / closing means 6 End plate 7 Coupling means 8 Toggle type mold clamping means 8a Toggle mechanism 8b Toggle drive device 8c Nut 9 Nut 10 Connecting plate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F202 AP06 AP11 AR02 AR07 CA11 CL12 CL22 CL32 CL39 CL42 4F206 AP064 AP11 AR024 AR074 JA07 JL02 JM02 JM03 JN34 JP13 JP18 JQ83 JT05 JT32 JT38

Claims (5)

[Claims] 1. A movable platen (2) is moved with respect to a fixed platen (1), and dies (4a, 4b) attached thereto.
Opening and closing means (5) for opening and closing, a connecting means (7) for fixing a tie bar (3) and integrally connecting an end plate (6) to a fixed board (1), a movable board (2) and an end plate (6), a toggle type clamping device for an injection molding machine, comprising: a toggle type clamping device (8) for applying a clamping force to the mold (4). (8) The mold clamping device for an injection molding machine, wherein the stroke is a total value of a mold clamping stroke for generating a predetermined mold clamping force and a stroke of an initial mold opening process. 2. The mold closing device according to claim 1, wherein the mold closing process from the mold opening limit to the mold touch is closed by the mold opening / closing means (5), and then the toggle-type mold clamping means (8). After injection and cooling, the mold is loosened, and the initial mold opening process is opened by the toggle mold clamping means (8), and then the mold opening process up to the mold opening limit is performed by the mold opening / closing means (5). A) a method of controlling a mold clamping device of an injection molding machine. 3. The mold closing device according to claim 1, wherein the mold closing step from the mold opening limit to a position immediately before the mold touch is closed by the mold opening / closing means (5), and then the toggle-type mold clamping means (3). In 8), the mold is closed, the mold is closed, and after injection and cooling, the mold is released, and the initial mold opening process is performed by the toggle-type mold clamping means (8). Subsequently, the mold opening process up to the mold opening limit is performed. A method for controlling a mold clamping device of an injection molding machine, wherein the method is performed by a mold opening / closing means (5). 4. The mold clamping device for an injection molding machine according to claim 3, wherein the position immediately before the mold touch is changed within a range of a stroke in an initial mold opening step of the toggle mold clamping means (8). Control method. 5. The degree of bending of a toggle mechanism (8a) when switching from the mold opening / closing means (5) to a toggle mold clamping means (8) is set in advance. 2. The method for controlling a mold clamping device of an injection molding machine according to claim 1.