JPH0122136B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold clamping device for an injection molding machine that can be used for injection compression molding, foam molding, or the like.

In the injection compression molding method, in which molten resin is injected and filled into a closed mold, and then the closed position of the mold is changed to compress the molten resin, a means is required to change the closed position of the mold into two stages. It is said that As means for changing the closed position, a method is adopted in which the closed position of the movable plate is detected and hydraulically blocked to control the mold position during injection and filling, or the mold position is mechanically controlled. There is.

Among the conventional means described above, when using a hydraulic block, high pressure cannot be applied during injection, and the position of the mold is unstable, making it difficult to perform highly accurate molding.

As for mechanical means, a technology in which a wedge is provided at the joint of the mold to determine the closing position, and control is performed by varying the amount of push of the wedge
6054 (see Japanese Patent Publication No. 56-7860), and a technique in which a plurality of stop cylinders are provided in addition to the mold clamping cylinder to control the closing position of the movable plate, and control is performed using the stop cylinders and rods (see Japanese Patent Publication No. 7860/1986). ).

In the above-mentioned wedge-based control means, the mold structure is more complex than a normal mold because the mold is equipped with a wedge and a cylinder for moving the wedge.
In addition, there were other problems such as lack of versatility.

In addition, control using a stop cylinder and rod requires a stop plate and an electric motor to adjust the position of the rod that passes through the stop cylinder, which not only complicates the structure around the clamping cylinder but also increases the cost. There are drawbacks.

Although this invention mechanically controls the position of the movable plate, it is not particularly complicated as in the conventional device, and only a specific movable plate control device is provided between the movable plate and the mold clamping cylinder. Therefore, it is an object of the present invention to provide a device that can change the closing position of a mold extremely easily and with high precision.

In addition, this invention has excellent versatility, as the retraction position of the movable plate can be freely adjusted, and it can be used not only for injection compression molding, but also as a mold clamping device for ordinary injection molding or foam molding machines. The present invention aims to provide a mold clamping device with a new configuration.

The present invention will be explained in detail below using illustrated examples.

1 is a fixed plate, 2 is a movable plate, 3 is a mold clamping cylinder, and movable plate 2 is fixed plate 1
The mold clamping cylinder 3 is movably supported by a plurality of tie bars 5, 5 which are installed horizontally across the support plate 4 of the mold clamping cylinder 3.

Between the fixed plate 1 and the movable plate 2, a pair of split molds 6 and 7 are arranged, one of which is fixed to the fixed plate and the other to the movable plate. It is designed to open or close every two reciprocating movements.

A mold clamping ram 8 that is integral with the piston 9 and protrudes from the mold clamping cylinder 3 is connected to the center portion of the movable plate 2 on the mold clamping cylinder side.
By moving forward and backward, the mold is opened and closed, and the mold is strongly clamped.

10 is a device for controlling the retreating position of the movable plate 2 provided between the movable plate 2 and the mold clamping cylinder 3, and a holding member 11 fixed to the mold clamping cylinder side;
and a control member 12 provided around the movable plate side of the mold clamping ram 8.

The holding member 11 has a cylindrical shape having a through hole 13 between the mold clamping ram 8 and the control member 12 in the center, and a plurality of recesses 14 and 1 around the through hole 13.
4 are formed in the radial direction.

The control member 12 is tubular and integrally has convex portions 15, 15 corresponding to the concave portions 14, 14 at its rear end, and rotates in the circumferential direction around the mold clamping ram 8. is fitted in the axial direction by a flange 16 so as not to move. Further, a hydraulic cylinder 17 for rotation, which is rotatably supported on the movable plate 2, is connected to the end of the control member 12 on the movable plate side.

In the example shown in FIG. 7, the holding member 11 of the control device 10 is constructed from a fixed part 11a and a movable part 1b, and a screw is attached around the cylindrical fixed part 11a connected to the end of the mold clamping cylinder 3. A mold thickness adjusting ring 19 is screwed into the mold thickness adjusting ring 19, and the movable part 11b is elastically fitted to the tip of the mold thickness adjusting ring 19 with a spring member 20 provided thereon. The distance between the fixed plate 1 and the movable plate 2 can be adjusted according to the mold thickness by moving in the direction. In this case, the through hole 13 and the recesses 14, 14 are provided on the end surface of the movable portion 11b.

Next, the operation of the mold clamping device will be explained using injection compression molding as an example.

First, the movable plate 2 is moved forward by the mold clamping cylinder 3 to close the molds 6 and 7. The mold is closed to a predetermined position before the joint surfaces of the molds come into contact with each other, as shown in FIG. 2, and there is a gap that allows the movable mold 6 to move forward secondarily. Form and place.

Next, by rotating the control member 12 in the circumferential direction, the protrusions 15, 15 at the rear end of the control member, which have come out of the support member 11 from the recesses 14, 14 of the through hole 13, are removed.
It is shifted from the recesses 14, 14 and positioned on the end face of the support member, as shown in FIG. After such an operation, the hydraulic circuit of the mold clamping cylinder 3 is left as is, and molten resin is injected and filled into the mold. In this case, injection pressure is applied to the movable plate side, but the movable plate 2 is supported by the control member 12 in contact with the end surface of the holding member 11, and the movable plate 2 is resists injection pressure.

When injection filling is completed, pressurized oil is added to the mold clamping cylinder 3 to secondarily pressurize the mold clamping ram 8, and the third
As shown in the figure, the movable plate 2 is moved forward until the joint surfaces of the molds come into contact with each other. As a result, the mold is clamped, and the resin within the mold is compressed.

To open the molds 6 and 7 after the above-mentioned molding, first, the control member 12 is returned to its original position by rotation, and the positions of the concave portions 14 and the convex portions 15 and 15 are aligned. In this way, the control member 12 can move backward together with the mold clamping ram 8 even if the convex portion protrudes from the rear.
The state returns to the state shown in FIG.

When performing foam molding, the movable plate 2 is moved forward at low pressure until the joint surfaces of the molds 6 and 11 completely come into contact (see FIG. 3). Next, foamed resin is injected and filled into the mold. Since the movable plate 2 is kept under low pressure, the control member 12 moves back until it comes into contact with the holding member 11 during injection and filling, and the cavity volume increases as shown in FIG. 2. As a result, the filled resin foams and expands within the mold.

In the above embodiment, the control member side is rotated, but this rotation may be performed on the holding member side, and the rotation means may also be mechanical means other than the hydraulic cylinder.

As described above, this invention provides a control device between the movable plate and the mold clamping cylinder, which includes a fixed holding member on the mold clamping cylinder side and a control member provided around the movable plate side of the mold clamping ram. By joining these parts, we made it possible to move the movable plate in two stages and compress or expand the resin in the mold, so there was no need to detect the position of the movable plate and block the hydraulic pressure. There is no
Since high pressure can be applied during injection, products with high dimensional accuracy can be molded. Furthermore, since the movable plate is mechanically controlled, positioning accuracy is improved and thick precision parts such as lenses can be molded. Furthermore, since the control device is installed using the space between the movable plate and the mold clamping cylinder, there is no need for a mold with a specific structure. It is easy to operate as it is controlled by moving in and out of contact with the control member, and can be adjusted to the optimum mold volume by using an adjustment ring, etc. When the control device is not activated, it can be used as a normal mold clamping device. It has many features including versatility such as being able to be used for foam molding.

[Brief explanation of drawings]

The drawings illustrate the mold clamping device according to the present invention, and FIGS. 1 to 3 are schematic vertical sectional views showing the operation in order, FIG. 4 is a sectional view taken along the line of FIG. 1, and FIG. FIG. 2 is a sectional view taken along the line in FIG. 2, FIG. 6 is a sectional view taken along the line shown in FIG. DESCRIPTION OF SYMBOLS 1... Fixed plate, 2... Movable plate, 3... Mold clamping device, 6, 7... Mold, 8... Mold clamping ram, 10... Control device, 11... Holding member, 12... Control member, 13
...Through hole, 14...Recess, 15...Convex part.

Claims (1)

[Claims] 1. In a device that opens, closes and clamps a mold between a fixed plate and a movable plate by moving the movable plate connected to a clamping ram of a mold clamping cylinder, the movable mold between the movable plate and the clamping cylinder A device is provided to control the retracted position of the plate,
The movable plate control device consists of a holding member fixed to the mold clamping cylinder side and a control member provided around the movable plate side of the mold clamping ram, and when either one rotates, these members come into contact with each other during injection. A mold clamping device for an injection molding machine, characterized in that the mold clamping device for an injection molding machine is configured to control the retraction of a movable plate within a certain range.