JP2732773B2 - Method of setting mold clamping force of toggle-type mold clamping device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art A conventional injection compression molding apparatus is disclosed in Japanese Patent Application Laid-Open No. 61-283520. The injection compression molding apparatus shown here is a so-called direct-acting type, in which a movable plate is directly attached to a piston rod of a mold clamping cylinder, and the movable plate is moved at the same speed (the same amount of movement) as the piston rod. It can be moved. In some injection compression moldings, a molten resin is injected into a cavity at a predetermined mold closing stroke position where the mold is not completely closed, and a compression process is started from the middle of the mold closing. That is, there is a molding method in which the compression stroke is made relatively long and the molten resin is sufficiently compressed. This method is often performed in foam molding and the like.

[0003]

However, the conventional direct-acting injection compression molding apparatus as described above has a problem that it is troublesome to control the speed of the movable platen. In the case of molding with a longer compression stroke,
It is necessary to control the speed of the movable platen over a long stroke. That is, in the injection compression molding, a compression force is applied by reducing the cavity volume (advancing the movable platen) with respect to the molten resin supplied to the mold cavity, but controlling the speed of the movable platen from the start of compression. There is a need to. In the case of a direct-acting type mold clamping device, the final compression step is performed in a state where the movable mold is brought into contact with the fixed mold (mold touch state). In order to avoid damage to the mold, it is necessary to decelerate the movable platen from a position before the abutment position, and it becomes troublesome to control the speed of the movable platen. In order to solve this problem, it is conceivable to use a toggle type mold clamping device. Even if the toggle head is driven at a constant speed, the moving speed of the link end portion (movable platen side) increases as the links are bent in a broken line, even if the crosshead portion of the toggle mechanism is driven at a constant speed. The movable platen has a characteristic that the moving speed on the movable platen side becomes smaller as the members are extended in a straight line, and the movable platen stops at the position where the links of the toggle mechanism are completely extended in a straight line. . That is, the movable platen side can be decelerated (stopped) without decelerating the crosshead side (mold clamping cylinder side) of the toggle mechanism. However, when injection compression molding is performed using a toggle-type mold clamping device, a final pressing force corresponding to the force increase rate of the toggle mechanism is generated at a position where the links of the toggle mechanism have extended linearly. However, there is a problem that the magnitude of the final pressing force cannot be easily adjusted by the supply relief 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 clamping force of the clamping device can be easily adjusted by adjusting the limit value of the hydraulic pressure supplied to the clamping cylinder. The mold clamping force in the case of the device is determined by how many mm the toggle mechanism extends the tie bar.If the amount of compression of the molten resin is a problem as in the case of injection compression molding, it depends on the elasticity of the resin used. Since the elongation of the tie bar changes, it is difficult to determine the tie bar elongation uniquely. An object of the present invention is to solve such a problem.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems by forming a test molding using an actual molten resin and setting a mold clamping force based on the test results.
That mold clamping force setting method of a toggle type mold clamping apparatus of the present invention, in a state of being stretched to fill the toggle mechanism, the movable side mold is fixed mold by rotating the tie bar nuts while maintaining this state supply and mold position setting step of setting the position of the whole movable part such as the movable plate so as to be located at the position of the mold touch or mold touch verge, a predetermined amount of the molten resin in the mold閉途the mold cavity and After that, the test molding process of performing compression molding on a trial basis by positioning the mold at the set position, and the dimensions of the test molded product and the target dimensions
The direction and amount of rotation of the tie bar nut are determined based on the difference
A compression amount setting step of calculating and determining a mold clamping position of the entire movable part.

[0005]

A maximum mold clamping force adjusting step for adjusting a relative position between the whole movable side of the mold clamping device and the fixed platen so that a predetermined mold clamping force acts on the mold closed via the toggle mechanism. . That is, by rotating the tie bar nut in a state where the toggle mechanism is fully extended, a mold touch position for setting the position of the entire movable portion such as the movable platen so as to be located at a position just before the mold touch or the mold touch. The difference between the setting step, the test molding step of supplying a predetermined amount of molten resin to the mold cavity and performing test molding, and the dimensions and target dimensions of the test molded article
Calculates the direction and amount of rotation of the tie bar nut based on the dimensions
And a compression amount setting step of determining the mold clamping position of the entire movable part. This completes the preparation for injection compression molding by the mold clamping device using the toggle mechanism. A predetermined amount of molten resin is injected into the mold cavity at a predetermined timing during closing of the mold via a toggle mechanism by supplying hydraulic pressure to the mold clamping cylinder. A predetermined pressing force can be applied to the mold with the toggle mechanism fully extended.
Thereby, compression molding is performed. As the toggle mechanism changes the posture from the bent state to the extended state, the mold decelerates from the maximum speed and finally stops, so that injection compression molding can be performed without performing complicated deceleration control.

[0006]

FIG. 1 shows an embodiment of the present invention. The mold clamping housing 34 is arranged at a position facing the fixed platen 32.
A movable plate 30 is provided between the fixed plate 32 and the mold housing 34.
Is arranged. The mold clamping housing 34 and the movable platen 30 are connected by the toggle mechanism 12. That is, the plurality of links of the toggle mechanism 12 have their one ends connected to the mold clamping housing 34 and the other ends connected to the movable platen 30, respectively. Fixed board 32
And the mold clamping housing 34 are connected to four tie bars 36 (FIG. 3).
) And a tie bar nut 14. The tie bars 36 respectively penetrate the movable platen 30. That is, the movable platen 30 is guided by the tie bar 36 for movement in the axial direction. A movable mold 38 is fixed to the movable plate 30, and a fixed mold 40 is fixed to the fixed plate 32. The mold clamping cylinder 10 is attached to the mold clamping housing 34. Mold clamping cylinder 1
The zero piston rod 10a penetrates the center of the mold clamping housing 34 and is connected to the crosshead 12a of the toggle mechanism 12. The tie bar nut 14
A sprocket 16 is provided integrally with the sprocket. A motor 2 for driving the chain is provided in the mold clamping housing 34.
0 is attached. A chain 18 is wound around each sprocket 16 and the motor 20. The sprocket 16, the chain 18, and the motor 20 constitute a tie bar nut rotating device. The rotation detector 22 is attached to the mold clamping housing 34 at a position facing the tie bar nut 14. Rotation detector 22
Can detect the rotational position of the tie bar nut 14. The position sensor 24 is provided at a position facing the movable mold 38. The position sensor 24 can detect the position of the movable mold 38. A controller 26 is provided for inputting a signal of the measurement position from the position sensor 24 and a signal from the rotation detector 22 respectively. The controller 26 can store a rotation amount of the tie bar nut 14 corresponding to a unit movement amount of the movable platen 30, receives a signal of a measurement position from the position sensor 24, and has a desired molded product thickness. It is possible to input the difference between the dimension and the thickness of the molded article at the time of test molding described later. The controller 26 performs a predetermined calculation based on the measured position signal from the position sensor 24, and can output a drive signal to the motor 20 according to the calculation result. That is, the controller 2
6 is capable of controlling the tie bar nut rotating device. A pilot check valve 28 is provided in a pipe connecting the mold-side oil chamber 10b of the mold-clamping cylinder 10 to a hydraulic source (not shown).

Next, the operation of this embodiment will be described. Even if the toggle mechanism 12 is fully extended in advance, the motor 20 is driven to move the tie bar nut 14 to the tie bar 36 so that the movable mold 38 does not collide with the fixed mold 40.
Move to the end side. First, the mold closing position of the movable platen 30 is adjusted. That is, with the toggle mechanism 12 fully extended, the piston rod 10
The mold-clamping-side oil chamber 10b and the mold-opening-side oil chamber 10c are each blocked so that the relational position between a and the crosshead portion 12a does not change. In this state, as shown in FIG. 4, the motor 20 is driven to adjust the rotational position of the tie bar nut 14 so that the movable mold 38 and the fixed mold 40 touch the mold. That is, positioning of a movable portion such as the movable platen 30 is performed. 4 to 6 do not show the nut rotation device and the like. Next, the blocking state of the mold clamping cylinder 10 is released, and the mold opening side oil chamber 10c of the mold clamping cylinder 10 is released.
The movable mold 38 is positioned at the mold open position by supplying hydraulic pressure to the mold, and test molding is performed. That is, the molten resin 42 is injected into the mold cavity at a predetermined mold opening stroke position (for example, a 10 mm opening position) shown in FIG. 5, and compression molding is performed. After the molding, the mold is opened, the test molded product is taken out, the dimension in the compression direction (thickness dimension) is measured, the difference dimension from the target dimension is calculated, and this is input to the controller 26. For example, when the thickness of the test molded product is 2 mm thicker than the target size (insufficient mold clamping force), “−” is stored in the memory of the controller 26.
2 ". The controller 26 calculates the rotation direction and the rotation amount of the tie bar nut 14 from the input sign and the difference dimension, and drives the motor 20 to position the tie bar nut 14 at a desired position. That is, in the case of the above example, as shown in FIG. 6, the movable platen 30 is moved from the position indicated by the imaginary line to the position indicated by the solid line by rotating the tie bar nut 14 in the screwing direction by the calculated amount. Will be done. Depending on the required precision, the final positioning is performed by repeating the test molding and the work of correcting the position of the tie bar nut 14. Thus, the adjustment of the mold clamping force for the injection compression molding is completed, and the production can be started. At the time of production, unlike the direct-acting type, there is no need for troublesome control such as detecting the position of the movable plate for each shot and controlling the speed.

In the description of the above embodiment, the setting work of the mold clamping force is performed in the state of touching the mold.
The setting operation of the mold clamping force can be performed just before the mold touch. Further, in the description of the above embodiment, the nut rotating device includes the sprocket 16 and the chain 1.
8 and the motor 20. However, the present invention is not limited to this.
It is also possible to use a gear system as disclosed in Japanese Patent No. 7060. Furthermore, in the description of the above-described embodiment, the difference dimension with respect to the target dimension is input to the setter 26. However, the present invention is not limited to this. Number (for example, 1
0), and the operator can select the notch position (for example, the third notch, that is, the advance amount of 0.9 mm) according to the difference dimension. In this way, a user accustomed to the operation of the direct pressure injection molding machine can operate the toggle injection molding machine with the same operational feeling as that of the direct pressure injection molding machine.

[0009]

As described above, according to the present invention, it is possible to perform injection compression molding utilizing the advantages of the toggle type mold clamping device. That is, once the mold clamping force is set, injection compression molding can be performed without performing complicated control such as measuring the position of the movable part and controlling the speed. Further, since the compression end position does not necessarily need to be in the mold touch state, damage to the mold can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a view showing a tie bar nut rotating device together with a mold clamping cylinder and the like.

FIG. 3 is a view as seen from the direction of arrow 3 in FIG. 2;

FIG. 4 is a diagram showing a state in which a mold is touched by extending a toggle mechanism.

FIG. 5 is a view showing a state during injection molding and test molding during mold closing;

FIG. 6 is a diagram illustrating a mold-clamping stroke setting step.

[Explanation of symbols]

 Reference Signs List 10 mold clamping cylinder 10a piston rod 10b mold clamping side oil chamber 10c mold opening side oil chamber 12 toggle mechanism 12a crosshead 14 tie bar nut 16 sprocket (nut rotating device) 18 chain (nut rotating device) 20 motor (nut rotating device) 22 Rotation detector 24 Position sensor 26 Controller 28 Pilot type check valve 30 Movable plate 32 Fixed plate 34 Mold clamping housing 36 Tie bar 38 Movable mold 40 Fixed mold

Claims (1)

(57) [Claims] In a state in which the toggle mechanism is fully extended, a tie bar nut is rotated while maintaining this state, whereby the movable mold is brought into a position just before the fixed mold and the mold touch or the mold touch. A mold position setting step of setting the position of the entire movable portion such as a movable platen so as to be positioned; and, by supplying a predetermined amount of molten resin to the mold cavity during the closing of the mold, by positioning the mold at the set position. a test molding step for tentatively compression molding, data based on the difference dimension of the dimension and the target dimension of the test moldings
A compression amount setting step of calculating a rotation direction and a rotation amount of the inverter nut and determining a mold clamping position of the entire movable part; and a mold clamping force setting method of a toggle-type mold clamping device for injection compression molding.