JPH064264B2 - 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 order to precisely control the injection compression process, the preliminary mold clamping force in the mold clamping process and the cavity internal pressure in the injection process are accurately measured. Need to understand.

As a means for measuring the mold clamping force and the cavity internal pressure in the injection process, a pressure sensor is fitted into the parting surface and cavity of the mold, and the mold clamping force is measured by the pressure sensor on the parting surface. There is known a method of measuring the internal pressure of the cavity in the injection process by using the pressure sensor.

However, in the above method, for each molding die,
Since a process for attaching the pressure sensor is required, the cost is likely to increase.

In addition, the cavity internal pressure due to injection has a pressure gradient that it is high near the gate and decreases as it moves away from the gate, and the measured value depends on the mounting position of the sensor. In addition, with pressure measurement using a pressure sensor, the pressure in the vicinity of the pressure sensor can be accurately measured, but it is difficult to select the mounting position of the sensor to measure the accurate pressure, and control cannot be done without accurate pressure measurement. .

As one means for solving the above problems, Japanese Patent Publication No. 53-11974 discloses a method of detecting the amount of deformation such as elongation of a tie bar at the time of injection and thereby detecting the cavity internal pressure. This method is to attach a sensor directly to the tie bar between the fixed plate and the movable plate with the mold attached, measure the extension of the tie bar between the two plates with respect to the opening amount of the mold, and use this to measure the cavity internal pressure. Is.

However, the elongation of the tie bar due to the injection filling pressure is
Since it extends over the entire tie bar, it is not possible to accurately grasp the cavity internal pressure by measuring the partial extension of the tie bar, and further improvement is required to measure the cavity internal pressure from the tie bar extension. ing.

The present invention was conceived in order to solve the problems in the above injection compression molding machine, and its object is to accurately detect the expansion and contraction amount of the entire tie bar at the time of injection with an extremely simple configuration, An object of the present invention is to provide a new injection compression molding machine capable of reliably measuring the pressure inside the cavity.

[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 tie bar is formed hollow and the reference rod is inserted into the inside, and one end of the reference rod is fixed to one supporting plate and the other end is projected from the other supporting plate. The tie bar expansion / contraction detector is provided over the projecting end and the other support plate.

[Operation] In the above configuration, even if the tie bar extends due to the internal pressure of the cavity, the reference rod whose one end is fixed does not change. Therefore, a dimensional difference occurs between the tie bar and the reference rod. Is detected as the elongation of the entire tie bar.

[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 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.

Further, as shown in FIG. 2, the tie bar 4 whose both sides are fixed to the support plates 1 and 2 by the nuts 15 and 15 is formed in a hollow shape, and a reference rod 16 serving as a reference for detecting the amount of expansion and contraction is provided therein. It is loosely inserted.

The reference rod 16 is longer than the tie bar 4, and a connecting plate 17 is attached to the end portion on the support board 1 side by screwing.
One end is fixed to the support board 1 via the connecting plate 17.

The other end of the reference rod 16 projects from the support board 2, and a detector of a measuring instrument such as a digital micrometer measures the amount of expansion and contraction of the tie bar 4 across the projecting end and the nut 14 of the support board 2. 18, the nut 14
It is attached by abutting against.

Since only one end of the reference rod 16 is fixed to the support board 1, the reference rod 16 is not affected by the expansion and contraction of the tie bar 4, and has a constant length at any time during the mold clamping process and the injection process. Hold.

When the amount of expansion of the tie bar 4 is detected by the detector 18, since the expansion of the tie bar 4 has not occurred before the injection process, the value of the meter at this time is first set to zero.

When preliminary mold clamping is performed in the mold clamping process, the tie bars 4 and 4 are stretched due to the mold clamping pressure of the mold clamping cylinder 6, and the elastic deformation recovery force of the tie bars 4 and 4 causes the mold clamping pressure proportional to the elongation amount. Occur.

At that time, the tie bars 4 and 4 extend, but the reference rod 16 does not extend, and the support plate 2 moves outward by the amount of extension of the tie bars 4 and 4. Therefore, the detector 17 is connected to the tie bars 4 and 4 proportional to the load pressure. The amount of elongation is measured by the meter.

In the injection process, when the resin pressure is applied to the cavity by the injection pressure, the high pressure causes the tie bars 4 and 4 to expand, and the elastic deformation recovery force of the tie bars 4 and 4 causes the cavity pressure proportional to the expansion amount.

At that time as well, the reference rod 16 does not extend, and the support board 2 moves by the amount of extension of the tie bars 4, 4, so that the detector 18 measures the amount of extension of the tie bars 4, 4 proportional to the load pressure by the meter.

As described above, the expansion amount of the tie bars 4 and 4 is proportional to the tie bar load pressure. Therefore, by measuring the expansion amount of the tie bars 4 and 4 during injection compression molding, it is possible to easily and accurately measure the preliminary mold clamping force and the average. It is possible to detect various cavity pressures.

[Advantages of the Invention] As described above, according to the present invention, the tie bar is formed hollow, the reference rod is inserted thereinto, one end of the reference rod is fixed to one support board, and the other end is fixed to the other. The amount of expansion and contraction of the tie bar can be accurately detected because the tie bar expansion and contraction detector is provided over the protruding end and the other support plate. By grasping the cavity internal pressure, it is possible to easily perform precise control of the injection compression process.

In addition, the tie bar is made hollow, the reference rod is placed inside it, and the detector is attached to the protruding end of the reference rod, so the structure is extremely simple and no special operation is required for detection. Therefore, it has a feature that the effect as an injection compression molding machine is great.

[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 Mold ... ...... Nut, 16 ………… Standard rod 18 ………… Expansion / contraction detector

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. With the cooling of the molded product after gate sealing, the elastic deformation recovery force of the tie bar acts on the mold in the thickness direction of the molded product to form a hollow tie bar in an injection compression molding machine for compression molding the molded product. Then insert the reference rod inside,
One end of the reference rod is fixed to one support board, the other end projects from the other support board, and a tie bar expansion / contraction detector is provided between the projecting end and the other support board. Characteristic injection compression molding machine.