JPH064265B2 - 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 order to perform precision molding with such an injection compression molding machine, it is necessary to accurately control the open position of the mold and the compression process.

However, when the elongation of the tie bar at the time of mold clamping and injection is used, the thermal expansion coefficient is not determined due to the temperature change of the outside air, the frictional heat of the sliding movable plate, the heat generation due to the expansion and contraction of the tie bar, etc. Since the amount of expansion and contraction of the tie bar inside is unstable, it is difficult to measure and control the amount of expansion and contraction of the tie bar.

The present invention has been conceived in view of the above circumstances, and a new object thereof is to make it possible to accurately grasp the expansion and contraction amount of a tie bar in an injection compression process by stabilizing the thermal expansion of the tie bar by a simple means. An object is to provide an injection compression molding machine.

[Means for Solving the Problems] The feature of the present invention according to the above object is to configure a mold clamping device such that a tie bar provided by fixing both ends to a pair of support plates extends due to the cavity internal pressure in the injection process. Then, while the mold is opened by the internal pressure of the cavity, the elastic deformation recovery force of the tie bar acts on the mold in the thickness direction of the molded product as the molded product cools after gate sealing, and the molded product is compression molded. In the injection compression molding machine, the temperature of the tie bar is adjusted.

[Operation] In the above configuration, since the tie bar is temperature-controlled to a predetermined temperature, the coefficient of thermal expansion of the tie bar during the injection compression process becomes constant and the amount of expansion and contraction is also determined. The process is precisely controlled.

[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 by 4.

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 to which the mold 8 is attached is mounted on the machine base within a range in which the tie bars 4 and 4 are allowed to extend. A linear bearing guide 9 for linear motion on the machine base shared with the movable plate 7 is provided on the machine base via a linear bearing 10 for linear motion so as to move.

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 frictional 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 is reduced. By making the size 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.

Further, as shown in FIG. 2, the tie bar 4 whose both sides are fixed to the support boards 1 and 2 by the nuts 15 and 15 is formed in a hollow shape, and further the couplers 16 and 16 are provided at the protruding ends from the nuts 15 and 15. And the couplings 17, 17, the hoses 18, 18 are connected.

The hoses 18, 18 are connected to a temperature controller (not shown), and supply and discharge the liquid medium from the temperature controller to the tie bar 4. The temperature of the tie bar 4 is adjusted by the liquid medium flowing through the inside 4b, whereby the thermal expansion is kept constant and the expansion / contraction amount during the injection compression process is also kept constant.

[Advantages of the Invention] As described above, according to the present invention, since the tie bar is temperature-controlled, the coefficient of thermal expansion of the tie bar during the injection compression process becomes constant and the amount of expansion and contraction is also determined. Thus, the open position of the mold and the compression process can be accurately controlled.

[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, and FIG. 2 is a vertical side view of a tie bar portion. 1, ... Support board, 3 ... Machine stand 4 ... Tie bar 5 ... Mold clamping cylinder, 6 ... Mold clamping ram 7 ... Movable plate, 8 ... Mold 15 ... … Nuts, 16 ……… Couplers 17 ……… Couplings, 18 ……… Hoses

Claims (1)

[Claims] 1. A mold clamping device is configured so that tie bars provided by fixing both ends to a pair of support plates extend by the cavity internal pressure in the injection process, and the mold is slightly opened by the cavity internal pressure. In the injection compression molding machine that compresses the molded product by applying elastic deformation recovery force of the tie bar in the thickness direction of the molded product with cooling of the molded product after gate sealing, temperature control of the tie bar. An injection compression molding machine characterized by.