JPH03262608A - Die for molding of thermosetting resin - Google Patents

Abstract

PURPOSE:To obtain inexpensively a die for molding of thermosetting resin which is durable for molding operation of exceeding 1,000 times, by providing a cavity core comprised of an epoxy resin cast body to be obtained by shaping a cavity, an intermediate force which surrounds the cavity core by holding a fixed gap and is comprised of a top and bottom forces and a positioned metallic framelike part and a rubber packing material which prevents molding resin from entering into the gap. CONSTITUTION:The title die is constituted of three-layer structure of an intermediate force 1 and a top and bottom forces 11, 21 which are arranged on the top and bottom of the same. The intermediate force 1 is constituted of a framelike part 2 comprised of a metallic material, which is the same as that of the top and bottom forces, and a plurality of cavity cores 3 comprised of a molding tool made of resin where a principal part 4 of the cavity is formed as a recessed part. The cavity core 3 is comprised of an epoxy resin composition and holds a gap 7 between the cavity core 3 and the framelike part 2. An 0 ring 5B which is held into an 0 ring groove 5A is provided within the gap 7. Then the fringe part of the cavity 4 also is provided with a packing groove 6A, a rubber packing 6B having a T-shaped section is projected out to a gap 7 side and the 0 ring 5B is provided close by the rubber packing 6B. With this construction, since entering of molding resin into the gap 7 is prevented and the resin entered into the gap 7 is cured, thermal stress to be generated can be avoided.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention is for thermosetting resin molding used in transfer molding or liquid injection molding of electrical parts etc. at a low molding pressure of 50#/- or less. Molds, especially molding molds suitable for high-mix, low-volume production.

[Conventional technology]

Manufacturing methods of thermosetting resin molded products, such as transfer molding and liquid injection molding, shorten the molding time.
In addition, the dimensional accuracy and shape stability of molded products are excellent, so it has become widely used in the manufacturing field of many glass parts as a manufacturing method suitable for mass production. For molds, for example, after machining the cavity using iron-based metal xsD-i-i'e specified in the Japanese Industrial Standards, the surface is carburized and quenched, and then hard chrome plating is applied using a high-grade metal such as Ryuko. Mass-produced molds are known that have high mold surface hardness and can withstand 100,000 molding cycles.

In the field of electrical and electronic equipment, there is a coexistence of mass-produced models and high-mix, low-volume models, and the amount of thermosetting resin molded products used in high-mix, low-volume models is limited. Many molds have about 100 to 1,000 pieces, and molds made of synthetic resin made of a facilitable liquid silicone rubber casing or an epoxy resin composition are known as molds used under such conditions. In other words, liquid resin is injected and solidified around the cut product model, a cavity corresponding to the shape of the product is formed in the liquid resin, and this is used as an intermediate mold for the mold. be.

[Problem to be solved by the invention]

Molding molds for mass production that can mold more than 100,000 pieces are expensive because they require advanced Kaloe technology, and the manufacturing cost is several hundred thousand yen for a small one, and several hundred for a large one. It can reach up to 10,000 yen. Therefore, when such an expensive molding die is used to manufacture 100 to 1,000 molded products, the initial cost is extremely high, and this reflects on the product cost, resulting in a significant increase in the cost of the molded product. A problem occurs.

On the other hand, using a resin mold has the advantage of significantly lowering the initial cost and lowering the product cost. While maintaining the molding temperature at around 80°C to 150°C, pour several pieces of molded resin into the cavity.
In transfer molding, housing or liquid injection molding of thermosetting resins, which are press-fitted at molding pressures of 0 to 9/ad, mold clamping is difficult due to the low rigidity of the resin mold at the molding temperature. The mold may be deformed due to load or molding pressure.
It becomes difficult to perform repeated molding, and the dimension p
A fatal defect occurs in that it is difficult to obtain molded products with small variations in shape and shape.

An object of the present invention is to eliminate the drawbacks of resin molds and to obtain an inexpensive mold that can be stably used for molding operations of 100 times or more by transfer molding or liquid injection molding.

[Problem t-Means for solving]

In order to solve the above problems, the present invention has a three-layer structure consisting of a metal intermediate mold in which the main part of the cavity is formed, and metal upper and lower molds in which a heating heater is embedded. A cavity core made of an epoxy resin cast body in which a cavity has been formed by pressing a button on a thermosetting resin molding die, and a cavity core made of an epoxy resin cast body having a cavity formed therein, and a cavity core formed by holding and surrounding this cavity core for a predetermined period, and an upper mold and a lower mold. An intermediate mold consisting of a metal frame portion positioned in the mold, and intrusion of molding resin into the gap 1
It shall be equipped with a rubber packing material for one stop.

[Effect]

The structure of the present invention is that, in a molding die having a three-layer structure of an upper mold, an intermediate mold, and a lower mold, the intermediate mold is a cavity core as a resin mold having a main part of the cavity; The cavity core is composed of a metal frame-shaped part that holds and surrounds the cavity core for a predetermined period of time, and a rubber backing material is interposed in the gap between the cavity core and the frame-shaped part to perform sealing and positioning. Additionally, the frame part has a simple structure with a rectangular hole into which the cavity core is inserted, and can be simply constructed using the same metal material as the upper and lower molds, and the cavity core is cast using epoxy resin. By the method, a cavity of arbitrary shape and size can be made with precision.
Easy to form. Also, take into account the difference in thermal expansion between the metal frame and the resin cavity core containing aluminum powder as a filler! If a gap as large as 70.1 m is maintained between the cavity core and the frame-shaped part or between the upper mold and the mold, the molding operation can be carried out without applying thermal stress to the cavity core during molding. In addition, rubber packing material is placed in these gaps for sealing and positioning to prevent resin from entering the gaps and to transmit the molding pressure applied to the cavity to the frame, upper mold, and lower mold. Since the deformation of the cavity core can be stopped by 1 km, the function of repeatedly molding a thermosetting resin molded product can be obtained.

〔Example〕

The present invention will be explained below based on examples.

Fig. 1 is a side cross-sectional view showing a thermosetting resin molding mold according to an embodiment of the present invention separated vertically, and Fig. 2 is an enlarged cross-sectional view showing the main parts of the molding mold according to an embodiment. It is a diagram.

As shown in the figure, the molding die consists of a three-layer structure of an intermediate mold 1, an upper mold 11p and a lower mold 21 arranged above and below the intermediate mold 1, and the intermediate mold 1 is made of the same metal material as the upper mold and the lower mold (e.g. The frame part 2 is made of the above-mentioned iron-based alloy KSD-11 with an expansion coefficient of 1.4 x 10-5/°C, etc., and the main part 4 of the cavity is made of a resin I!! mold formed as a recess. In the case of the example, the window size of the frame portion 2 into which the cavity core 5 is inserted is 25 m x
The window is formed by machining a metal plate of 50 m square hole and thickness t=iQw.

- The cavity core 3 is made of an epoxy resin composition containing aluminum powder as a filler and an alicyclic amine as a hardening agent, and its coefficient of thermal expansion is 52.7X10/℃, and its outer diameter is It is formed into a rectangular shape smaller than the window size by Δ□ to maintain a gap 7 between it and the frame-shaped part 2, and its height h is also set to be Δh lower than the thickness t=iotm of the frame-shaped part 2, so that the gap 7 An O-ring 5B housed in an O-ring groove 5A is provided inside to position the cavity core with respect to the gas seal D and the frame portion 2.

A backing groove 6A is also provided on the periphery of the cavity 4 in the housing, and the cross section T positioned by this backing groove is
It is configured to interpolate the level difference Δh between the frame portion 2 and the cavity core 5 by disposing a letter-shaped rubber bracket 6B.

A plurality of positioning holes 9 are formed in the frame-shaped part 2 of the housing, and positioning pins 23 provided on the lower mold. A positioning pin (not shown) on the upper mold side is fitted into the positioning hole 9 to form a three-layer mold, and this mold is held in a hydraulic press or the like and tightened to about 100#/-. Mold clamping is performed by applying pressure. Furthermore, upper mold 1
1 and the lower mold 21 are equipped with heaters 12 and 2 at key points.
2 is embedded, and the mold temperature is maintained at the molding temperature, for example, 150°C. Further, on the lower surface 12A of the upper mold 11 covering the opening of the cavity 4, a gate 26 is formed so as to communicate with each of the cavities 4 via a runner 25t to a sprue (not shown) which is a resin injection port. The thermosetting molding resin sent from the injection molding machine is subjected to molding at a pressure of, for example, 10#/-. In addition,
The interface between the intermediate mold and the upper mold (parting surface) has a thickness of several tens of microns.
A vent consisting of a minute gap of about 1.5 m is provided, and the air inside the cavity is forced out into the mold by the pressure of the invading resin, including voids! The result is a molded product with no

In the molding die configured as described above, when the molding temperature is 150°C, the difference in thermal expansion between the frame portion and the cavity core is such that the difference in thermal expansion between the cavity core and the long side of the window at room temperature (30°C) is The amount of expansion of the core is 0.078 times larger. Therefore, if the dimension of the long side of the cavity core 3 at 30°C is made in advance to be smaller than the window dimension of the frame part 2 by 0.078 m, the cavity core 3 can be formed at a molding temperature of 150°C. Molding can be performed without any thermal stress acting between the frame portion 2 and the frame portion 2.

However, since the cavity core, which is a resin-cast product, has dimensional errors that occur during casting, the gap length Δ9 is the above thermal expansion difference of 0.078 mm ÷ 2 = 0, and the dimensional error is 0.1 mm to 0.39 m. It is preferable to maintain a distance of about 0.14 mm, and the same applies to the short side of the cavity core. Since the gate 26 supplies molding resin to the cavity 4 across the gap 7, there is a concern that the molding resin may enter the gap 7 from the gate 26 at this portion. By protruding the rubber packing 6B toward the gap 7 side and providing it near the O-ring 5Bt rubber packing 6B, it is possible to prevent the molding resin from entering the gap 7. Therefore, the resin that has entered the gap 7 will harden. Thermal stress generated can be avoided.

FIG. 3 is a cross-sectional view showing the method for manufacturing the cavity core in the above-mentioned embodiment, in which the outside diameter of the cavity core 3 is 24°75!111×49.
, 7 pieces, and a cavity model 34 corresponding to the cavity 4 and a groove model 36 simulating the backing groove 6A are attached to predetermined positions with adhesive or screws on the bottom surface of the molded resin 59. For example, an epoxy resin composition containing a predetermined amount of aluminum powder (for example, Ciba Geigy's trade name Araldai) T-301/R
-4,-.- Donor T-5 (mixture of 11/H-4) was injected and released from the mold when it became semi-cured by heat treatment at 60°C for about 12 hours, and heated to 180°C. 2
Post-curing is performed for about 0 hours. After the hardening process, the cast body has an inclination angle of 0 on the liquid side and a height H of 9.8.
A cavity core 3 of W (Δkl=0.2m) is finished, and a silicone resin mold release agent (for example, product number KS700 manufactured by Shin-Etsu Silicone Co., Ltd.) is applied to the surface of the cavity 4, and heat treated at 220°C for about 2 hours. , a cavity core 3 having a cured release film is obtained.

The cavity core 3 formed as described above is attached to the frame portion 2 through the O-ring 5Bt, and is attached to the upper mold 11 through the rubber packing 6B'r. They are integrated by applying a mold clamping load of 10 ta+ while being held between the lower molds 21. In this state, the mold temperature is preheated to a molding temperature of 150°C by the heaters 12 and 22, and the molding pressure is increased to I Dkg.
Transfer molding in which epoxy resin molding resin is injected with /ctll was repeated over 1000 times, but no abnormality was observed in the mold, especially in the cavity core 3, and a molded product with the specified dimensional accuracy was obtained. It was done. As a comparative example, transfer molding was attempted under the same conditions as above using a mold in which the entire intermediate mold was made of epoxy resin casting, but cracks occurred in the intermediate mold after only three molding operations. , subsequent molding became impossible.

[Effects of the Invention] As described above, the molding die according to the present invention is configured such that the frame-shaped portion is provided in the intermediate mold so that the mold clamping load does not directly act on the cavity core, and the molding die is configured so that the mold clamping load does not directly act on the cavity core and the frame-shaped portion. If111'fr between the gap and between the cavity core and the upper mold:
The cavity core is elastically supported by the mold part by the backing material provided and interposed in this gap, and the molding pressure is transmitted to the mold part and supported while avoiding thermal stress acting on the cavity core. did. As a result, compared to conventional molding molds in which the entire intermediate mold is made of epoxy resin casting, the thermal stress acting on the cavity core, mold clamping pressure, and molding pressure are significantly reduced.
A complete mold for thermosetting resin molding that can withstand more than one molding operation can be provided at a significantly lower cost than conventional all-metal molds. In addition, by replacing the cavity core, molded products of different shapes can be made using one mold (metal part), which significantly reduces the initial cost when manufacturing molded products of high variety, low volume production. Therefore, it is possible to provide molded products economically.

[Brief explanation of drawings]

FIG. 1 is an exploded cross-sectional view of a thermosetting resin molding mold according to an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of the main parts of the embodiment, and FIG. FIG. 3 is a cross-sectional view showing a method for manufacturing a cavity core. DESCRIPTION OF SYMBOLS 1... Intermediate mold, 2... Frame-shaped part, 3... Cavity core, 4... Cavity, 5A, (5A... Backing groove, 5B, 6B... Backing, 7... gap,
9...Positioning hole, 11...Upper mold, 12.22...
・Heating heater, 21° lower mold, 23... Positioning bottle, 31... Casting mold, 34... Cavity model, 36
...Groove model, 39...Casting resin, Δ9. Δh...
Gap length. To＼Representative Patent Attorney Yama
Ro Iwao - 1st and 2nd area

Claims (1)

[Claims] 1) In a thermosetting resin molding mold having a three-layer structure of a metal intermediate mold in which the main part of the cavity is formed, and metal upper and lower molds in which a heating heater is embedded,
Consists of a cavity core made of an epoxy resin cast body into which a cavity is formed, and a metal frame-shaped part that surrounds this cavity core with a predetermined gap and is positioned on the upper mold and the lower mold. A mold for molding a thermosetting resin, comprising an intermediate mold and a rubber packing material that prevents molding resin from entering the gap.