JPH091610A - Heater of transfer mold - Google Patents

Abstract

PURPOSE: To uniformize the temperature of cavity blocks by a method in which a heater for heating the cavity blocks at a specified temperature is placed in a heating plate on which the cavity blocks and a center block are mounted, and in the longitudinal direction of the heater, the middle part is established as a low heat generation area, and both end parts are established as high heat generation areas. CONSTITUTION: A heater 4 which is buried in a heating plate 3, a mounting base, mounted with cavity blocks 1 and a center block which are bonded together keeps the cavity blocks at a specified mold temperature. The heater 4, in combination with a temperature sensor set in the heating plate 3 and a controller, controls the temperature of a mold. In the heater 4, the winding pitch of a coil-shaped heating wire 4b is changed in three sections in the longitudinal direction so that the pitch of the wire 4b is rough in the middle low heat generation area A and dense in both end high heat generation areas B. The heat generation of the heater as a whole is made 400W, or 100W for the area A and 150W for the area B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heater for a transfer molding die.

[0002]

2. Description of the Related Art First, FIG. 2 shows a conventional structure of a transfer molding die and a die heating heater mounted on the die. In FIG. 2 (a), 1 is a cavity block having a cavity 1a and a runner 1b, 2 is a center block having a pot 2a and a runner 2b, 3 is a mounting base mounted by connecting a plurality of cavity blocks 1 and 2 together. The heating plate 4 also serving as a table is a heating heater embedded in the heating plate 3, and the heating heater 4 is aligned with the arrangement of the cavity blocks 1 so that the heater insertion holes 3a of the heating plate 3 are arranged so as to be arranged directly below the respective cavity blocks. 2 is a rod-shaped cartridge type heater installed by inserting the heaters into the outer cylinder 4a in a coil shape along the longitudinal direction, as shown in FIG. 2 (b). The structure is laid.

The heater 4 is a cavity block 1
Is maintained at a predetermined mold temperature, and in actuality, the temperature of the mold is controlled in combination with a temperature sensor and a controller installed inside the heating plate 3. Here, in the conventional heater 4, the coil-shaped heating wire 4b is wound at an equal pitch in the entire length region, and a predetermined Joule heat generation amount (for example, an electric power amount 400 W) is generated over the entire length thereof to generate the cavity block 1. It is set to heat.

[0004]

By the way, in the transfer molding die, it is desirable that the surface temperature of the die is as uniform as possible. If the surface temperature of the die is non-uniform and there is a large variation in the temperature distribution, the mold will be It is known that defects such as voids, pinholes, and pinching are likely to occur in products.

In this regard, when the temperature distribution of the cavity block 1 is actually measured for the transfer molding die equipped with the heater (heat generation capacity 400 W) 4 of FIG. 2B, the temperature distribution as shown in FIG. 2C is obtained. (The point x in the figure represents the temperature measurement point), and there is a temperature difference of 16 ° C. between the highest temperature point and the lowest temperature point. The cause of this large temperature difference is that the heating heater 4 has a uniform heat generation distribution in the longitudinal direction, whereas the cavity block 1 has a larger heat radiation area at both end portions than in the central portion in the longitudinal direction. There is a lot of heat.

The present invention has been made in view of the above points, and an object thereof is to improve the mold temperature, in particular, to heat the cavity block to a uniform temperature so that a molded product with few molding defects can be molded. It is to provide a heater for a transfer molding die.

[0007]

According to the present invention, the above object is to reduce the heat generation in the central portion along the longitudinal direction of the rod-shaped heater embedded in the heating plate in parallel with the cavity block. This is achieved by setting the area and both ends to the high heat generation area. In order to set the low heat generation region and the high heat generation region in the heater, the heating wire wound in a coil shape has a coarse pitch at the center along the longitudinal direction of the heater and a fine pitch at both ends. It shall be installed and constructed.

[0008]

With the above structure, the distribution of the amount of heat generated along the longitudinal direction of the heater is small at the center and large at both ends. That is, with respect to the cavity block mounted on the heating plate, the heat generation amount of the heater facing the central portion where the heat radiation amount is small is small, and the heat generation amount of the heater facing the both end portions where the heat radiation amount is large is large. As a result, it is possible to compensate for the distribution of the amount of heat radiation along the longitudinal direction of the cavity block, suppress the occurrence of a large temperature difference in the entire length region of the cavity block, and bring it closer to soaking heating, and there is no molding defect. It is possible to mold various molded products.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.
It will be described based on. In the figure, the same members corresponding to those in FIG. 2 are designated by the same reference numerals. That is, the structure of the transfer mold in FIG. 1 is the same as that in FIG. 2, but the rod-shaped heater 4 embedded in the heating plate 3 is similar to that in FIG.
As shown in (b), the winding pitch of the coil-shaped heating wire 4b is changed in three sections divided along the longitudinal direction. That is, the heating wire 4b is wound in a coarse pitch in the central low heat generation area A, and the heating wire 4b is wound in a high pitch in the high heat generation areas B at both ends. The amount of heat generated is 100 W, and the amount of heat generated in region B is 15
It is distributed so that it becomes 0W.

As described above, the heater 4 of FIG. 1 (b) in which the heat generation amount distribution is set in consideration of the heat radiation amount distribution along the longitudinal direction of the cavity block 1 is used in the mold of FIG. 1 (a). When the temperature was measured at each point (6 points) of the cavity block 1 in a state where the cavity block 1 was equipped and the mold was heated by actually energizing the heater 4, the temperature distribution as shown in FIG. 1C was obtained.

As is clear from this temperature distribution, the temperature difference between the highest temperature point (173 ° C.) and the lowest temperature point (168 ° C.) is only 5 ° C., which is the conventional temperature difference shown in FIG. It can be seen that the mold temperature variation is smaller than that of the one (maximum temperature difference of 16 ° C.), and the temperature approaches uniform heating. Also,
The result of inspecting the molded product formed by actually operating the mold has also confirmed that molding defects such as voids, pinholes, and pinching hardly occur.

[0012]

As described above, by adopting the heater of the present invention, the transfer molding die, particularly the cavity block which is the main part of the die, can be heated uniformly, and thereby the void, By preventing the occurrence of molding defects such as pinholes and pinching, the quality of molded products can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an embodiment of the present invention, in which (a) is a configuration diagram of an entire molding die, (b) is a structural diagram of a heater, and (c) is a temperature distribution diagram of a cavity block.

2A and 2B are explanatory views of a conventional example, FIG. 2A is a configuration diagram of an entire molding die, and FIG. 2B is a structural diagram of a heater.
(C) Temperature distribution diagram of cavity block

[Explanation of symbols]

 1 Cavity Block 2 Center Block 3 Heating Plate 3a Heater Insertion Hole 4 Heating Heater 4b Heating Wire A Low Heat Generation Area B High Heat Generation Area

Claims (2)

[Claims] 1. A heater for heating a cavity block to a predetermined temperature by arranging it inside a heating plate to which a cavity block and a center block of a transfer molding die are attached, the heater being an electric heater along its longitudinal direction. In the case of a rod-shaped cartridge heater in which heat wires are laid in a coil shape and embedded in a position directly below the cavity block in parallel with the cavity block, the central portion along the longitudinal direction of the heater is a low heat generation region, and both ends are A heater for a transfer molding die characterized by being set in a high heat generation region. 2. The heating heater according to claim 1, wherein the heating wire wound in a coil shape is laid at a coarse pitch at the central portion along the longitudinal direction of the heater and at a fine pitch at both ends. Heater for transfer mold.