JPH06304983A - Method for adjusting mold clamping force of toggle type mold clamping device - Google Patents

Abstract

PURPOSE:To mold a molded product of good thickness accuracy by computing the stroke of a piston of a mold clamping cylinder by means of the set compression amount of a mold and various performances and characteristics of design of a toggle type mold clamping device and setting a toggle mechanism stretching straight on the position of mold clamping side stroke end and applying the set compression force to a mold. CONSTITUTION:First, a movable side mold 17 is positioned on the mold opening position through a mold clamping cylinder 10, a toggle mechanism 11 and a movable platen 16. When a controller 30 is operated, the compression force and the set compression amount X set in a mold clamping setting section 26 and a compression amount setting section 28 are input into a computating equation, and the stroke S from the compression starting position to the stroke end of a piston 10d of the mold clamping cylinder 10 is computed and the piston 10d is positioned on the given stroke position. The adjustment of the position is made by a tie bar nut 22 so that the compression process of the piston 10d is started from the position of stroke S (the position where molds 17 and 18 are opened by the set compression amount X), and finally the toggle mechanism is stretched straight and the set compression force is applied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold clamping force adjusting method for a toggle type mold clamping device.

[0002]

2. Description of the Related Art As a conventional injection compression molding apparatus, there is one disclosed in Japanese Patent Application Laid-Open No. 61-283520. The injection compression molding device shown in this is a so-called direct-acting type, in which the movable platen is directly attached to the piston rod of the mold clamping cylinder, and the movable platen is at the same speed (same movement amount) as the piston rod. It can be moved. Some injection compression moldings inject a molten material into a cavity at a predetermined mold closing stroke position where the mold is not closed, and start the compression process halfway through the mold closing. That is, there is a molding method in which the molten material is sufficiently compressed by making the compression stroke relatively long. This method is used for foam molding.
It is often done.

[0003]

However, the conventional direct-acting injection compression molding apparatus as described above has a problem that it is troublesome to control the position of the movable plate. That is, in injection compression molding, it is necessary to apply a compressive force stepwise by advancing the movable plate stepwise in the compression step of reducing the cavity volume with respect to the molten material supplied to the mold cavity. In some cases, in order to remove the distortion of the molded product due to compression molding, a step of slightly increasing the cavity volume during the molding (strain removal step) may be necessary. In order to control the movable platen, a highly accurate flow rate control device for stopping the movable platen at a desired position is required, which makes it difficult to control the position of the movable platen. As a solution to this problem, it is possible to use a toggle type mold clamping device. In the toggle type mold clamping device, the amount of movement of the toggle mechanism on the movable platen side is small (in proportion to the reciprocal of the power multiplication factor of the toggle mechanism) with respect to the amount of movement of the toggle head on the crosshead portion. Even if the movement amount on the side is controlled with normal position accuracy, the position on the movable platen side is controlled with good accuracy (proportional to the reciprocal of the force multiplication factor of the toggle mechanism). Also, since the movable platen will stop at the position where the links of the toggle mechanism are fully extended in a straight line, the movable platen side can be moved without decelerating the crosshead side (mold clamping cylinder side) of the toggle mechanism. Deceleration (stop)
It is possible to operate. However, when injection compression molding is performed using the toggle type mold clamping device, a final compression force is generated according to the force increase rate of the toggle mechanism at the position where the links of the toggle mechanism are fully extended in a straight line. However, there is a problem that the magnitude of the compression force at a predetermined stroke position during mold clamping cannot be easily adjusted by the supply pressure of the mold clamping cylinder as in the case of the direct acting type. That is, in the case of the direct acting type, the magnitude of the mold clamping force of the mold clamping device can be easily adjusted by adjusting the value of the hydraulic pressure supplied to the mold clamping cylinder. The mold clamping force in the case of is determined by how many mm the tie bar is stretched by the toggle mechanism, and when a force that resists the compression of the molten material acts as in the case of injection compression molding, this resistance force causes the tie bar to stretch. Since the amount will change, it will be difficult to set the mold clamping force. In addition, in the conventional mold clamping force adjustment method that does not assume injection compression molding, it is only necessary to keep in mind the magnitude of the mold clamping force during final mold clamping, and it is not necessary to consider the progress of the process. Therefore, there is a possibility that the adjustment state will be different as shown in the range sandwiched between (b) and (c) in FIG. Therefore, even if the final set mold clamping force F has the same value, there is a possibility that important intermediate states during the injection compression molding are scattered. If injection compression molding is performed up to this point, molding as intended will be almost impossible. In the case of the diagram (c) in the figure,
This means that compression molding cannot be performed at all (compressive force acts only during mold clamping, and almost no compressive force during mold closing). The present invention aims to solve such problems.

[0004]

According to the present invention, the piston stroke range of a mold clamping cylinder from the start of compression of a molten material injected into a mold to the end of compression is defined by a set compression force and a set compression amount (movement amount). ) And to solve the above problems. That is, the method for adjusting the mold clamping force of the toggle type mold clamping device of the present invention is based on the set compression amount X of the mold and the design specifications of the toggle type mold clamping device from the mold clamping side stroke end of the piston of the mold clamping cylinder. When the stroke S up to the compression start position is calculated and the piston of the mold clamping cylinder is positioned at the mold clamping side stroke end, the set compression force F acts on the mold with the toggle mechanism extended linearly. , The tie bar nut of the mold clamping device is rotated.

[0005]

[Function] A set compression amount on the mold side is set so that the molten material injected into the mold starts to be compressed from a predetermined mold closing position.
And the piston position of the mold clamping cylinder is adjusted based on the design specifications of the toggle mechanism. Next, while maintaining these relationships, the mold clamping force is adjusted so that the set compression force acts on the mold at the mold clamping position where the mold moves by the set compression amount. As a result, it is possible to start compressing the molten material in the mold from the mold closing halfway position where the mold is opened by the dimension corresponding to the set compression amount. Further, when the mold moves from the compression start position in the mold closing direction by the set compression amount, the set compression force can be applied to the mold. That is, it is possible to perform injection compression molding according to the setting as shown by the diagram (a) in FIG. With the set compression force applied,
Since each link of the toggle mechanism can be extended straight, without performing pressure control as in the case of the direct drive type, do not apply a compression force above the set compression force to the mold. be able to. Further, a molded product having a stable wall thickness can be molded without requiring complicated speed control as in the case of the direct acting type.

[0006]

FIG. 1 shows a toggle type mold clamping device to which the present invention is applied. A mold clamping cylinder 10 is attached to the mold clamping housing 12. Piston rod 1 of mold clamping cylinder 10
0a is connected to the crosshead 14 of the toggle mechanism 11. The left end of the link of the toggle mechanism 11 is connected to the mold clamping housing 12. The right end of the link in the figure is connected to the movable platen 16. A fixed plate 18 is fixed at a position facing the movable plate 16. The mold clamping housing 12 and the stationary platen 18 are connected by four tie bars 20 (note that only two tie bars are shown in FIG. 1). Tie bar nut 2 at the end of tie bar 20
2 are each screwed in. Each tie bar 20 penetrates the movable platen 16. That is, the movable platen 16 is guided to move in the axial direction by the tie bars 20.
A movable mold 17 is attached to the movable platen 16,
A stationary mold 19 is attached to the stationary platen 18. The molten material can be injected into the mold cavity C from a not-shown injection device at a predetermined stroke position during mold closing. At the mold position shown in the figure, a gap corresponding to the set compression amount X is formed between the movable mold 17 and the fixed mold 19, and the compression force is applied to the molten material in the mold cavity C from this position. Is designed to work. A mold clamping side oil chamber 10b of the mold clamping cylinder 10 from a hydraulic source (not shown)
Oil is discharged from the mold opening side oil chamber 10c and the piston 10d is advanced from the illustrated compression start position to the stroke end (only the stroke S) by moving the movable mold 17 to the toggle mechanism 11. It is possible to move forward by the set compression amount X corresponding to the reciprocal of the power multiplication factor. Thereby, the tie bar 20 of the mold clamping device can be extended by a predetermined length. A mold clamping force sensor 23 is provided at the end side position of the tie bar 20. The mold clamping force sensor 23 is a force meter and can measure the mold clamping force (compressive force) acting on the tie bar 20. Assuming that the movable side mold 17 is pressed (clamped) to the fixed side mold 19 with the set compression force F (see FIG. 2) with the toggle mechanism 11 fully extended, the set compression amount X and the stroke. The relationship with S can be obtained from the design specifications of the toggle mechanism 11. The stroke S is also related to the strain amount R of the mold clamping device when the set compression force F is applied. Since this strain amount R can be obtained from the set compression force F and the specifications of the mold clamping device. After all, if the set compression amount X and the set compression force F are determined, the piston 10 of the mold clamping cylinder 10 is determined based on the design specifications of the apparatus.
The stroke S of d can be obtained. Movable mold 1
A position sensor 24 is provided at the fixed portion facing the position 7. The position sensor 24 is a movable mold 1 from the reference position.
The moving position of 7 can be detected. The controller 30 of the injection molding machine includes a mold clamping force setting unit 26 and a compression amount setting unit 28.
And are provided. A set compression force F can be set in the mold clamping force setting unit 26, and a set compression amount X can be set in the compression amount setting unit 28. A predetermined arithmetic expression can be stored in the controller 30. The controller 30 can calculate the stroke S of the piston 10d of the mold clamping cylinder 10 based on the set compression force F, the set compression amount X, and the calculation formula.

Next, a method of adjusting the mold clamping force for the toggle type mold clamping device will be described. In advance, the controller 30
In, a predetermined arithmetic expression is stored. A set compression force F is set in the mold clamping force setting unit 26, and a set compression amount X is set in the compression amount setting unit 28. First, the stroke S of the piston 10d of the mold clamping cylinder 10 is adjusted. Piston 10 of mold clamping cylinder 10
d is located at the retracted position to the left of the illustrated position. Therefore, the movable side mold 17 includes the piston rod 10
It is located at the mold opening position on the left side of the illustrated position via the a, the toggle mechanism 11, and the movable platen 16. By driving the controller 30 in this state, the set compression force F and the set compression amount X set in the mold clamping force setting unit 26 and the compression amount setting unit 28 are incorporated into the calculation formula to perform the calculation. The stroke S of the piston 10d of the mold clamping cylinder 10 is calculated. Hydraulic pressure is supplied to the mold clamping cylinder 10 in response to a command signal from the controller 30, and the piston 1
0d is positioned at a predetermined stroke position. Next, the mold clamping force is adjusted. That is, the piston 10d of the mold clamping cylinder 10 is at the position of the stroke S shown in the drawing (the mold 17.1.
8 so that the compression process is started from a state in which the set compression amount X is opened to a position (opened by the set compression amount X), and finally the set compression force F acts in a state in which the toggle mechanism 11 is linearly extended. The tie bar nut 22 is rotated to position each part of the device. Signals from the mold clamping force sensor 23 and the position sensor 24 are used for this positioning.
For these adjustments, it is desirable to use an automatic adjusting device as disclosed in, for example, Japanese Patent Publication No. 61-35924. In this case, the mold thickness dimensions of the molds 17 and 19 to be used are also set in the controller 30, and the automatic adjusting device is driven according to a command signal from the controller 30 to automatically adjust the mold clamping force and the mold thickness. Will be adjusted accordingly. After that, the mold clamping force sensor 23 and the position sensor 24 may be removed from the apparatus.

After the adjusting work, the forming work is performed. As a result, injection compression molding is performed according to the settings shown in the diagram (a) of FIG. That is, the molten material is injected into the mold cavity C at a predetermined position on the mold closing stroke from the mold open state, and the compression of the molten material in the mold cavity C starts from the position opened by the dimension X from the mold closed position. To be done. The compressive force increases linearly while moving by the dimension X, and the predetermined compressive force F is applied to the mold 1 at the final mold clamping position.
Molding will be performed by acting on 7 ・ 19. That is, at the position where the piston 10d of the mold clamping cylinder 10 has stroked to the stroke end, each link of the toggle mechanism 11 is in a straight extended state, and the movable mold 17 stops at the final mold clamping position. . Therefore, accurate positioning of the movable mold 17 is easy, and the thickness dimension of the molded product can be made stable.

In the above description of the embodiment, the case where a linearly increasing compressive force is applied to the molds 17 and 19 has been described, but the movable mold 17 is stopped at each of a plurality of stroke positions. When the compressive force is applied in stages, the position of the piston 10d of the mold clamping cylinder 10 corresponding to the stop position of the movable mold 17 is calculated and the piston of the mold clamping cylinder 10 is used for molding. The amount of oil supplied to the mold clamping cylinder 10 may be controlled so that 10d is stopped at each desired position.

[0010]

As described above, according to the present invention, the desired injection compression molding can be performed even when the toggle type mold clamping device is used. Without the troublesome position control and speed control like in the case of direct-acting type mold clamping device,
A molded product with good thickness accuracy can be molded.

[Brief description of drawings]

FIG. 1 is a diagram showing a toggle type mold clamping device for carrying out the present invention.

FIG. 2 is a diagram illustrating a relationship between a compressive force and a strain amount.

[Explanation of symbols]

 10 mold clamping cylinder 10a piston rod 10b mold clamping side oil chamber 10c mold opening side oil chamber 10d piston 11 toggle mechanism 12 mold clamping housing 14 crosshead 16 movable plate 17 movable plate 18 fixed plate 19 fixed plate 20 tie bar 22 Tie bar nut 23 Mold clamping force sensor 24 Position sensor 26 Mold clamping force setting unit 28 Compression amount setting unit 30 Controller

[Procedure amendment]

[Submission date] June 3, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

Claims (1)

[Claims] 1. A stroke S from a stroke end on a mold clamping side of a piston of a mold clamping cylinder to a compression start position is calculated based on a set compression amount X of a mold and design specifications of a toggle type mold clamping device, When the piston of the clamping cylinder is positioned at the stroke end on the mold clamping side, it is necessary to rotate the tie bar nut of the mold clamping device so that the set compression force F acts on the mold with the toggle mechanism extended linearly. A method for adjusting mold clamping force of a toggle type mold clamping device for injection compression molding.