JPH0719771Y2 - Mold for high frequency molding - Google Patents

Description

TECHNICAL FIELD The present invention relates to improvement of a high-frequency molding die used for resin molding by heating by high-frequency dielectric.

2. Description of the Related Art Conventionally, in this type of mold, each of the cavity mold and the core mold is usually molded from a material having a small dielectric loss ratio, such as silicon.

However, even if this mold is made of a material with a low dielectric loss factor, it slightly heats up when a high-frequency voltage is applied, and it is also heated by conduction heat due to heat generation of the molded product. However, it is unavoidable that the cavity space becomes larger than a predetermined dimension due to thermal expansion of the mold itself, resulting in a dimensional error in the molded product. In particular, it is difficult to control the temperature of each mold for each molding, and it is inevitable that the dimensions will change due to the temperature difference between summer and winter.

In view of the above, the present invention has an object to provide an improved high-frequency molding die that can maintain its dimensions accurately even when the die is heated, heated, or the ambient temperature changes.

Means for Solving the Problems In a molding die for high-frequency molding according to the present invention, a stabilizing material having a die size with a low dielectric loss factor and a high stretch resistance is embedded in at least a cavity body. It is configured by A sheet material can be embedded as the mold size stabilizing material, and the sheet material can be formed of glass cloth. Further, a rod-shaped body may be embedded as a material for stabilizing the die size, and the rod-shaped body may be formed of a silicon carbide based ceramic material. Further, instead of the material for stabilizing the mold size, a short fiber material can be uniformly dispersed and embedded in the mold. As the short fiber material, glass fiber or silicon carbide whiskers can be used.

Action In this high-frequency molding die, the dielectric loss factor is small, and the linear expansion coefficient is smaller than the material of the die and the stretch resistance is large.
The stabilizing material can suppress the dimensional change of the mold body with respect to heat and can always form a molded product of a predetermined size. As a material for stabilizing the mold size, when a sheet material, particularly a glass cloth, is embedded, it can be mechanically firmly fixed and integrated into the mold body. Further, when a short fiber material such as glass fiber or silicon carbide whiskers is evenly distributed and embedded in the mold body, rigidity against external force can be imparted and mold deformation at the time of mold clamping can be suppressed.

Embodiments The following will be described with reference to the accompanying drawings.

This molding die is used to perform resin molding by heating by high frequency dielectric, and it is a cavity mold 1, in which mold bodies 1a, 2a are formed of a material such as silicon having a small dielectric loss factor.
It is provided with a core mold 2. Further, of these cavity molds 1 and core molds 2, at least the cavity mold 1 having the cavity space 3 has a small dielectric loss factor and a linear expansion coefficient smaller than that of the material forming the mold bodies 1a and 2a, so that it is resistant to expansion. A stabilizing material 4 having a good mold size is embedded in the body. As the material 4 for stabilizing the mold size,
Examples thereof include glass and silicon carbide, which may be embedded in the core 2 together with the cavity mold 1.

In the embodiment shown in FIG. 1, a glass cloth and a glass filament 40 are embedded as a material for stabilizing the mold size.
A primer is applied to the stabilizing material 40 in order to achieve adhesion with silicon. This stabilizing material 40 can be embedded during the molding of the mold itself. First, the silicon is cast to a position where the stabilizing material 40 of the mold size is embedded, and when the silicon is in a cured or uncured state, the stabilizing material 40 is laid and further silicon is cast to a desired position. Good. After the casting of the silicon is completed, if the casting jig of the casting molds 1a and 2a is placed in a vacuum state, the air existing in the stitches of the stabilizing material 40 can be degassed to mechanically strengthen both. It is preferable because it can be joined.

In the embodiment shown in FIG. 2, a ceramic rod-like body 41 having a small dielectric loss ratio such as silicon carbide is embedded as a material for stabilizing the die size.
It can be embedded and fixed inside the mold during the cast molding of a.

In the embodiment shown in FIG. 3, whiskers such as short glass fibers or silicon carbide are embedded as the material 42 for stabilizing the die size, which is evenly dispersed in the silicon forming the die and cast. Since the fiber material can be distributed and distributed in the body, many short fibers 42 individually partially suppress the thermal expansion, so that the mold bodies 1a and 1b do not thermally expand in any direction and the thermal expansion is suppressed as a whole. Also, it is preferable that rigidity against external force can be imparted to the mold bodies 1a and 2a and mold deformation at the time of mold clamping can be prevented. Further, in this case, if the surface layers 1b and 2b surrounding the cavity 3 are formed of a single material of silicon as shown in FIG. 4, it is possible to surely prevent the fiber traces from being attached to the outer surface of the molded product. it can.

In the molding die for high-frequency molding configured as described above, the mold body 1 is used as a high-frequency voltage is applied when a molded product is formed.
Although a and 2a also generate a little heat and are slightly heated by the conduction heat from the molded product, the mold bodies 1a and 2a have a smaller linear expansion coefficient and a larger stretch resistance than the mold bodies 1a and 2a. Stabilizing material 4
Since (40, 41, 42) are embedded, thermal expansion of the entire mold can be suppressed. Therefore, the dimensional change due to the thermal expansion of the molding die can be prevented, and the cavity space 3 does not change in shape, so that a molded product having a desired shape can be obtained. The thermal expansion can be suppressed even with humidity deformation in the summer and winter, and it becomes possible to form a mold that is stable against temperature.

As described above, according to the molding die for high-frequency molding of the present invention, it is possible not only to prevent thermal expansion of the mold body by embedding the material for stabilizing the mold size in the mold body, Since mechanical strength can be imparted to the mold body, it is possible to accurately form both the shape and size of the molded product even if a high-frequency voltage is applied to the clamped mold and resin molding is performed by dielectric heating. Is.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of a molding die according to the present invention, FIG. 2 is a side sectional view showing another embodiment of the molding die, and FIG. 3 is still another embodiment of the molding die. Fourth side sectional view showing an example
The drawing is a partially enlarged sectional view of the molding die shown in FIG. 1: Cavity type, 2: Core type, 1a, 2a: Mold body, 4: Stabilizer for mold size, 40: Sheet material, 41: Rod-shaped body, 42: Short fiber material.

Claims (8)

[Scope of utility model registration request] 1. A mold body (1a, 2a) made of a material having a low dielectric loss factor.
A mold having a cavity mold (1) and a core mold (2) for forming a resin by heating by high-frequency dielectric, and at least a dielectric body in the mold body (1a) of the cavity mold (1). Molding for high-frequency molding, characterized in that a stabilizing material (4) having a small loss factor and a linear expansion coefficient and a large expansion resistance, which is smaller than that of the material forming the mold body (1a), is embedded. Type. 2. The molding die according to claim 1, wherein a sheet material (40) is embedded as a material for stabilizing the die size. 3. The mold according to claim 2, wherein the sheet material (40) is made of glass cloth. 4. The molding die according to claim 1, wherein a rod-shaped body (4) is embedded as the material for stabilizing the die size. 5. The mold according to claim 4, wherein the rod-shaped body (4) is made of a silicon carbide type ceramic material. 6. The molding die according to claim 1, wherein a short fiber material (42) as a material for stabilizing the die size is embedded in the die in a uniformly dispersed manner. 7. The molding die according to claim 6, wherein the short fiber material (42) is made of glass fiber. 8. The mold according to claim 6, wherein the short fiber material (42) is a whisker of silicon carbide.