JPH0645163B2 - Injection compression molding machine - Google Patents

Description

The present invention relates to a synthetic resin injection compression molding machine.

[Prior Art] When molding a synthetic resin such as a lens or a disc plate of an optical disc that requires strict shape accuracy in the submicron unit, lose the high pressure generated in the cavity during the filling of the cavity in the injection process. Based on the relationship between the volumetric shrinkage rate of the synthetic resin material to be molded and the mold volume, the tie bar length, thickness, and material elastic modulus so that the tie bar can be expanded by the predicted amount and the mold can be opened. The high pressure energy of injection is stored in the form of expansion of the tie bar, and when the gate seal is completed, the cooling of the molded product progresses and the elastic deformation recovery force of the tie bar that extends in the thickness direction of the molded product is transferred to the mold. There is an injection compression molding machine that performs precision molding by compressing a molded product by acting on.

[Problems to be Solved by the Invention] In such an injection compression molding machine, in the injection compression process, both the movable platen and the support plate on the mold mounting side and the injection device to which the mold is touched by the nose are expanded and contracted. I am trying to move with it.

This movement is the most important for securing and maintaining the dynamic parallelism of the cavity mold and the core mold, and maintaining the positional relationship between the cavity and the core. The tie bar of the injection process and the compression process during cooling is used. If the expansion and contraction does not occur reliably and smoothly, it is impossible to obtain a molded product having excellent shape accuracy and dimensional accuracy.

In the injection molding machine where the direct pressure type mold clamping device so far is installed horizontally on the machine base, in order to maintain the parallelism of the movable plate and the support plate,
A method of increasing the diameter of the tie bar or increasing the rigidity to minimize the deflection, interposing a sliding plate between the lower surface of the movable plate and the bed, and minimizing the deflection of the tie bar due to the weight of the mold. Methods such as holding down to have been taken.

However, in the injection compression molding machine, the rigidity of the tie bar is intentionally significantly reduced, and the injection compression process is performed by utilizing the fact that the tie bar extends due to the high pressure of injection, so that the parallelism between the movable plate and the support plate is maintained. Is very difficult.

Even if a sliding plate is provided between the lower surface of the movable plate and the machine base, the machine base must always be horizontal during the injection compression process, and it is extremely difficult to keep the machine level horizontally during machining. That's right.

Furthermore, in the injection compression process, there is a frictional resistance against movement in the sliding part of the support plate on the die mounting side, and the frictional resistance works in the direction to prevent the movement of the support plate against the delicate movement due to expansion and contraction of the tie bar. , It hinders the delicate movement of the movable plate and the support plate and the maintenance of the dynamic parallelism.

Similarly, the frictional resistance of the sliding part of the injection device at the time of nozzle touch also works in a direction that prevents the injection device from reliably following the subtle movement of the tie bar expansion and contraction, and the movement of the support board. It hinders the subtle movement of the board and support board and the maintenance of dynamic parallelism.

The present invention has been conceived in order to solve the above problems, and its object is to provide a movable plate, a support plate on the mold mounting side, and an injection device for expanding and contracting a tie bar during an injection compression process with an extremely simple structure. The object of the present invention is to provide a new injection compression molding machine capable of reliably following the movement of the.

[Means for Solving the Problem] The feature of the present invention according to the above-mentioned object is that a tie bar provided as a guide for a movable plate provided over a support plate having a mold clamping cylinder and a support plate on the mold mounting side is used for the injection process. Equipped with a mold clamping device configured to extend by the cavity internal pressure and an injection device on the machine base, the mold is opened by the cavity internal pressure, while the elastic deformation recovery force of the tie bar is reduced as the molded product cools. In an injection compression molding machine that compresses and molds a molded product by acting in the thickness direction, the guide member of the movable plate is provided on the machine base up to the outside of the support plate on the mold mounting side, and the guide member is mounted on the mold mounting side. The support board is movably installed to extend the tie bar.

The guide member is a rolling guide, and the injection device is also movably installed on the guide member of the rolling guide provided on the machine base to reduce frictional resistance when the tie bar expands and contracts.

[Operation] In the above configuration, since the movable plate and the support plate on the die mounting side are installed on the machine base via the same guide member, the reference of the positional relationship between the movable plate and the support plate is determined, It is possible to maintain both dynamic parallelism during injection compression.

Also, since the sliding parts of the movable plate and the support plate are rolling guides, the frictional resistance of each sliding part is extremely reduced, and the follow-up movement of the support plate due to expansion and contraction of the tie bar during injection compression molding. Smoothness can be ensured, and dynamic parallelism can be reliably maintained.

Furthermore, by making the sliding part of the injection device a rolling guide, the sliding resistance of the injection device in the nozzle touch state is eliminated, and the injection device can be reliably moved against the movement of the support board against the expansion and contraction of the tie bar in the injection compression process. Move following.

[Embodiment] In the drawing, reference numerals 1 and 2 denote support plates installed on the machine base 3, and 4 and 4 denote four tie bars provided over the support plates 1 and 2, both ends of which are inserted into corners of the support plate. It is fastened and its tie bar 4,
A movable platen 7, which is connected to the mold clamping ram 6 of the mold clamping cylinder 5, is movably supported.

Numerals 8 and 8 are molds and are attached to the opposing side surfaces of the support board 2 and the movable board 7. The molds 8 and 8 are temperature-controlled sufficiently so that the thermal expansion does not change each time under the influence of the material temperature at the time of injection molding.

Further, the support board 1 having the mold clamping cylinder 5 is fixed to the machine base, but the support board 2 having the mold 8 attached thereto has the tie bar 4,
4 for linear movement provided on the machine base from the mold open position of the movable plate 7 to the outside of the support plate 2 so as to move on the machine base in the mold opening / closing direction within a range in which the extension of 4 is allowed. The linear bearing guide 9 is provided on the machine base together with the movable platen 7 through the linear bearing 10 for linear movement.

Reference numeral 11 denotes an injection device on the machine base, which is arranged via a linear bearing 13 on a separate linear bearing guide 12 and can be moved back and forth by a moving Linder 14 connected to the support board 2.

Therefore, in such a molding machine, the support plate 2 and the movable plate 7, and further the guide of the injection device 11 are used as rolling guides, and the friction resistance of the movement of the support plate 2 and the movable plate 7 due to the expansion and contraction of the tie bar in the injection compression process. By making as small as possible, the dynamic parallelism between the support plate 2 and the movable plate 7 in the injection compression process is maintained.

Further, the mold clamping ram 6 has sufficient rigidity to withstand the high pressures of mold clamping and injection, and the high pressures during mold clamping and injection are all absorbed by the elongation amount of the tie bars 4 and 4.

In order to realize injection compression molding, the tie bars 4 and 4 lose a high pressure in the cavity of the injection process and expand by an amount predicted from the relationship between the volumetric shrinkage rate of the molded product to be molded and the cavity volume. So that part 4a, 4a
Is formed with a small diameter.

Next, the injection compression molding operation will be described.

First, the mold clamping cylinder 5 performs mold clamping.

This mold clamping process is called preliminary mold clamping, and the molds 8 are closed by the forward movement of the movable platen 7. If the mold clamping force is applied even after the mold is closed, the force is applied from the movable plate 7 to the molds 8, 8.
Is transmitted to the support board 2 via.

This support plate 2 is installed so as to move on the linear bearing 9 against the tie bars 4 and 4 fixed to the support plate 1 together with the movable plate 7 in the mold closing direction by rolling guide without causing frictional resistance. Therefore, the dynamic parallelism is maintained, the mold clamping force acts as the tensile force of the tie bars 4 and 4, and the tie bars 4 and 4 are stretched, and the elastic recovery force of the tie bars 4 and 4 stretches them. Clamping pressure proportional to the amount is generated.

In this case, even if the injection device 11 is connected to the support board 2 via the moving cylinder 14, the injection device is also installed on the linear bearing guide 12 by the rolling guide so as to move without causing frictional resistance. Since it has been
It does not hinder the growth of tie bars 4 and 4.

Further, as the tie bars 4 and 4 are extended, the molds 8 and 8 between the movable plate 7 and the support plate 2 are moved with the amount of expansion of the tie bars 4 and 4 kept closed. Therefore, the reference of the positional relationship between the support board 2 and the movable board 7 is constant even after the mold clamping.

When the injection cylinder 11 touches the gate of the mold 8 clamped by the preliminary mold clamping by the moving cylinder 14 and the molten resin is injected into the cavity 15, the tie bar is applied to the filling pressure of the resin in the cavity. 4, 4 and 4 lose, and the stretch occurs there.

When the tie bars 4 and 4 are extended, the support board 2 is also moved in the mold opening direction together with the injection device 11 in an amount equal to the extension amount of the tie bars 4 and 4, and the molds 8 and 8 are slightly opened as shown in the figure. Occurs. Even in this case, since the movement is rolling guide,
Since there is almost no frictional resistance, the dynamic parallelism between the support board 2 and the movable board 7 is maintained.

After the injection and filling, when the gate seal is completed and the molten resin in the cavity is cooled, the tie bars 4 and 4 are restored to the original state, and the elastic deformation recovery force at that time is applied to the support board 2. It acts as a tensile force in the mold closing direction,
As shown in the drawing, the dies 8, 8 which are in the open state are pressed between the support plate 2 and the movable plate 7 to compress the molding resin in the cavity.

Even at this time, since the support plate 2 and the movable plate 7 move through the same linear bearing guide 9 by the rolling guide, the reference of the positional relationship between the two is constant, and the injection device 11 also uses the linear bearing guide 12 as a reference. Since it moves by rolling guide, there is almost no frictional resistance against the movement, and as a result, all of them follow the contraction of the tie bars 4 and 4,
The dynamic parallelism between the support board 2 and the movable board 7 is also maintained.

[Advantages of the Invention] As described above, according to the present invention, in the injection compression molding machine, the guide member of the movable plate is provided on the machine base up to the outside of the support plate on the die mounting side, and the guide member supports the die mounting side. Since the plate is movably installed and the tie bar can be extended, the dynamic parallelism between the support plate and the movable plate in the injection compression process is maintained, and the friction resistance during movement is reduced. Since the size is small, the tie bar can be surely moved to follow the slight expansion and contraction of the tie bar, and the amount of movement is also accurate, so that a molded product having excellent shape accuracy and dimensional accuracy can be injection-compressed.

Further, since the injection device is also installed on the guide member so as to move by rolling guide, it has a feature that it does not hinder the expansion and contraction of the tie bar.

[Brief description of drawings]

The drawings show one embodiment of the injection compression molding machine of the present invention. FIG. 1 is a side view, FIG. 2 is a plan view, and FIG. 3 is a mold and support at the time of preliminary mold clamping and injection filling. It is a top view explaining the physical relationship of a board. 1, 2 ... Supporting board, 3 ... Machine stand 4 ... Tie bar 5 ... Mold clamping cylinder, 6 ... Mold clamping ram 7 ... Movable board, 8 ... Mold 9, 12 ... Linear bearing guide 10 , 13 ...... Near bearing 14 ...... Moving cylinder 15 ...... Cavity

Claims (3)

[Claims] 1. A mold clamping device, wherein a tie bar provided as a guide for a movable plate provided over a support plate having a mold clamping cylinder and a support plate on the mold mounting side is configured to extend due to the cavity internal pressure in an injection process, Equipped with an injection device on the machine base, the mold is opened by the internal pressure of the cavity, while the elastic deformation recovery force of the tie bar acts in the thickness direction of the molded product as the molded product cools, and the molded product is compression molded. In the injection compression molding machine, the guide member of the movable plate is installed on the machine base up to the outside of the support plate on the mold mounting side, and the support plate on the mold mounting side is movably installed on the guide member to extend the tie bar. An injection compression molding machine characterized by being configured as possible. 2. The injection compression molding machine according to claim 1, wherein the guide member comprises a rolling guide. 3. The injection compression molding machine according to claim 1, wherein the injection device is movably installed on a guide member provided on a machine base, and the guide member comprises a rolling guide.