JPS58224730A - Temperature adjusting device of mold for injection molding - Google Patents

Abstract

PURPOSE:To prevent the generation of an residual stress and a sink mark in a resin near the outer peripheral edge of a disk like product, by providing the ring mold which contacts the most outer peripheral edge face of the disk with an independent temperature adjusting means in the mold for injection molding the disk like product. CONSTITUTION:In the mold for injection molding a disk like product to which the first mold 1, the second mold 2, a cavity 3, the coolant passage 4 for adjusting the temperature of the first mold 1, the coolant passage 5 for adjusting the temperature of the second mold 2, a stamper 6, the ring mold member 7 contacting the most outer peripheral edge face of the disk, etc. are provided, the coolant passage 10 for adjusting the temperature independently from the coolant passages 4, 5 for adjusting the temperature of the first and second molds is provided to the ring mold 7 which contacts the most outer peripheral edge face 8 of the disk and it is controlled at the temperature different from these.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature control device for a mold for injection molding a disc-shaped molded product, particularly an optical information recording disc.

Conventionally, there have been devices of this type as shown in FIG. 1 and FIG. 2 (a sectional view taken along the line A-A in FIG. 1).

In FIGS. 1 and 2, 20 is a first mold, 30 is a second mold, and a cavity space 40 is formed between the first mold 20 and the second mold 30.

Furthermore, 50b, 60b, and 70b are annular flow paths for cooling water, respectively, and a first cooling area is formed by the cooling water population 50a, the annular flow path 50b, and the cooling water outlet 50c, and similarly, the cooling water inlet 60a (70a) , annular channel 60
b (70b) and the cooling water outlet 60c (70c) form a second (third) cooling zone.

Such a plurality of spiral cooling channels is used to maintain a uniform temperature throughout the cavity space 40 and to reduce residual stress due to heat in the molded product.

However, although such conventional temperature control devices can reduce residual stress over almost the entire molded product, the outermost edge has a large contact area with the mold, so the cooling rate of the molten resin is affected. There were drawbacks such as residual stress and sink marks occurring on the inner periphery due to the difference.

In particular, in thin-walled molding such as optical information recording disks,
When the injection pressure is high, a density gradient is created in the resin near the outer edge, and residual stress generated during cooling due to the difference in resin density is added, which adversely affects signal reading at the outer edge due to birefringence and sinkage.

(In the case of optical discs, the shaped disc becomes part of the optical path of the reading beam.) In addition, sink marks interfere with the protection III film coating on the signal surface, and residual stress causes cracks on the outermost periphery due to aging. This caused the

In addition to adjusting the temperature of the mold, possible ways to reduce residual stress and whiskers include creating a gap around the outside of the mold to allow the resin to escape, and increasing the wall thickness around the outside of the molded product. . However, these methods are not preferred because they require changing the shape of the molded product and post-processing.

For reference, set the temperature to 1 on a conventional temperature controller.
The measurement results of the surface temperature of the mold cavity space 40 at 00°C are shown below.

Inner circumference of the disk 83°C Middle circumference of the disk 84°C Outer circumference of the disk 85・c Annular member forming the outermost edge of the disk 81℃ In the annular member forming the outermost edge, the molten resin and the mold It can be seen that the cavity surface temperature is several degrees Celsius lower than other parts due to the large contact area.

An object of the present invention is to overcome the drawbacks of the above-mentioned conventional techniques and to provide a temperature control device that can reduce residual stress, sink marks, and birefringence near the outermost peripheral edge of a molded product. be.

Hereinafter, the present invention will be specifically explained with reference to the drawings.

FIG. 3 is a sectional view of a temperature control device according to one embodiment of the present invention, and FIG. 4 is a sectional view of the same device according to another embodiment.

In Fig. 3, ■ is the first mold, 2 is the second mold, 3 is the cavity space formed by the first mold 1 and the second mold 2, and 4 is for temperature adjustment of the first mold 1. Refrigerant flow path 5 is a refrigerant flow path for temperature adjustment of the second mold 2, 6 is a stamper 17 is an annular mold member that contacts the outermost peripheral end surface of the disk, 8 is a mold surface 9 at the outer peripheral end of the cavity for air flow.・Gap and io
is a refrigerant flow path for temperature adjustment of the annular mold member 7. Reference numeral 11 denotes a bushing in which a vial 12 for flowing the molten resin into the cavity space 3 is formed. Annular mold member 7
Although it is possible to bring the outer peripheral end of the ring into close contact with the first mold 1, if necessary, an air gap 3 may be provided to thermally isolate the annular mold member 7 in the same manner as the air gap 9. It's okay.

If the mold temperature control device having such a configuration is used, first, the surface temperature of the cavity space 3 can be maintained at a uniform temperature over the front surface by the refrigerant flowing through the temperature control refrigerant channels 4 and 5.

This is based on the fact that the present invention also includes the structure shown in FIGS. 1 and 2 for cooling the flat surface of the disk. However, in the present invention, the temperature of the annular mold member 7 in contact with the outermost peripheral end surface of the disk is also controlled by the independent refrigerant flowing through the annular refrigerant flow path 10. Therefore, it is possible to maintain the mold surface 8 at the outer circumferential end of the cavity at approximately the same temperature as the other cavity surfaces, and it is also possible to maintain the mold surface 8 at a different temperature depending on the case.

In the above embodiment, the temperature of the annular mold member 7 is adjusted by flowing a refrigerant through the annular channel 10, but as shown in FIG.
It is also possible to heat only the Furthermore, a gap 15 of several microns can be provided at the contact portion between the annular mold member 7 and the second mold 2 to the extent that the molten resin does not flow out, thereby increasing the thermal insulation effect (this is shown in FIG. 3). The same applies to the examples.) Furthermore, air gap 9,
Instead of 13, a packing made of a heat insulating material may be used.

As explained above, since the temperature control device of the present invention has the above configuration, it is possible to independently adjust the temperature of the annular mold member that comes into contact with the outermost peripheral end surface of the disk. It is possible to reduce stress, birefringence associated with it, and sink marks occurring on the inner circumference.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional temperature control device, FIG. 2 is a sectional view taken along the line A-A in FIG. The figure is a sectional view of the same device according to another embodiment. DESCRIPTION OF SYMBOLS 1... First mold, 2... Second mold, 3... Cavity space, 4, 5... Refrigerant channel for temperature adjustment, 7...
Annular mold member, 10... Temperature adjustment refrigerant channel, 14.
...Banthee Evening. Patent applicant: Pioneer Corporation Figure 1

Claims (1)

[Claims] A temperature control device for a mold for injection molding a disk-shaped molded product, wherein a temperature control means independent of a cooling means for the flat surface of the disk is provided in an annular mold member that comes into contact with the outermost peripheral end surface of the disk. A temperature control device for injection molding molds.