JPS61172710A - Manufacture of resin molded parts - Google Patents

Abstract

PURPOSE:To prevent cracks from developing in a molded part by a structure wherein thermoplastic resin is poured and hardened so as to form a prepared hole, from which a female screw is developed by a self-tapping screw, in the forming of the molded part made of thermosetting resin. CONSTITUTION:Thermosetting resin 7 is injected in molding halves 1 and 1a so as to surround a portion, into which thermoplastic resin 9 is poured after the hardening of the thermosetting resin 6 and out of which a hollow space 10 is formed after a stepped pin 3 is removed. A self-tapping screw is applied to the hollow space 10. When a printed board and the like are intended to mount on a chassis, the mounting is done by screwing machine screws in the hollow spaces 10. The thermoplastic resin is poured in an undercut portion 14, which is made by boring a main body 12, so as to prevent the portion equipped with the hollow space 10 to be self-tapped from coming off. An erasing head is mounted on the chassis by screwing machine screws in said molded portion equipped with the hollow space 10 to be self-tapped.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a 5K resin molded product manufacturing method in which when parts are attached to a molded product made of a thermosetting resin, a tap portion for attaching the parts is molded with a thermoplastic resin.

In recent years, molded parts made of thermosetting resins such as B, M, C, etc. have been used for a wide range of purposes, but when attaching other parts to such molded parts, molded parts made of thermosetting resins such as brass A female screw member made of metal was press-fitted into a pilot hole provided in a molded part, and a machine screw was screwed into the female screw member L1. However, the tensile strength of thermosetting resins such as B, M, and C with glass filling of 15 mm is only 5 to 9/m'', so when press-fitting a female metal threaded member, it is difficult to heat the resin. Cracks occur in curable resin molded products, rendering them defective and rendering them unusable.

Taking these points into consideration, a method of fixing the internally threaded member using adhesive in the prepared hole was considered, but the adhesive entered the internally threaded part and made it difficult to screw in the small screw for tightening. It had the disadvantage of being

However, in this type of product, the female screw member is expensive and the mounting process is time consuming, so the finished product has to be expensive.

The present invention is a method for manufacturing a resin molded product, which has been made in view of the above points, and according to the present invention, the step of forming a bottom which becomes the outer diameter of the self-tapping part during molding of a molded product made of a thermosetting resin; It is characterized by a step of molding a thermoplastic resin having a cavity for a tap in the pilot hole.

The present invention will be described below with reference to Examples. In FIG. 1, cylindrical sleeve pins 2 are inserted into a plurality of desired locations within the space formed by +1 m of gold, and a stepped pin 3 is further inserted inside the sleeve pins 2. The large diameter portion 4 of this stepped pin is held in contact with the inner periphery of the sleeve pin 2, and the small diameter portion 5 is held at the center of the sleeve pin 2 by appropriate means so as not to shift its center position.

KB, M, and C in the molds 1 and 1a defined in this way.

When injecting thermosetting resin by heating it at 130°C to 140°C, this thermosetting resin is injected into the cavity 6 formed between the molds 1 and 1m and the sleeve pin 2. It hardens after a predetermined period of time. The cured thermosetting resin is indicated by 7.

After the thermosetting resin has hardened in this manner, the sleeve pin 2 is moved back as shown in FIG. 2 using a hydraulic cylinder or the like. After the sleeve pin 2 is retracted, the small diameter portion 5 of the stepped pin 3 still exists, and therefore a gap 8 is created so as to surround the small diameter portion 5 of the stepped pin 3.

Next, a thermoplastic resin such as Duracon resin is applied to the cavity at a temperature of 150°C to 100°C using a hot runner (not shown).
When heated to 60° C. and injected, this resin surrounds the small diameter portion of the stepped pin 3 and fills the gap 8, and hardens after a predetermined period of time.

The cured thermoplastic resin is indicated by 9. After the thermoplastic resin is cured in this manner, the mold fa is opened by appropriate means. Thereafter, when the thermosetting resin molded part 7 and the thermoplastic resin molded part 9 are pushed up from the mold 1, each molded part is removed from the Venus. This state is shown in FIG. As shown in this figure, there is a void I in the thermoplastic resin 90 portion where the stepped pin 3 is removed.
O is formed. This blank space becomes the self-tapping part.

The molded product taken out is, for example, as shown in Figures 5 and 6, and as will be clear from now on, when using the runner 11, it is possible to inject the thermoplastic resin 9 into multiple locations at the same time. It is. Such a molded product can be easily attached to a floppy disk chassis, for example, by screwing a small screw (not shown) into the space 10 when attaching a printed circuit board or the like to this chassis. .

Further, FIGS. 7 and 8 schematically show the erasing head of a tape recorder, and in the case of such a device, the erasing head main body 12 is made of thermosetting material using a mold as described above. The self-tapping portion 13 is formed by forming the resin from resin, and at the same time, by inserting a sleeper similar to the one previously described into the axial center of the main body and retracting the stepped pin after hardening.

Reference numeral 14 denotes an undercut portion formed in the main body 12, and the thermoplastic resin is injected up to this portion to prevent the self-tapping portion from being pulled out. The erasing head is attached to the chassis using machine screws on one part of the molded snow cover.

As described above, according to the present invention, since thermoplastic resin is injected and hardened into a molded product made of thermosetting resin so as to have a pilot hole for self-tapping, cracks may occur in the molded product made of thermosetting resin, unlike in the past. There are advantages in that there is no need to tighten the screw, and since no adhesive is used, the adhesive does not flow into the screw hole, making screwing in difficult.

[Brief explanation of the drawing]

Figures 1 to 4 are schematic cross-sectional views showing the process sequence of the method of the present invention. Figure 1 shows the state in which the sleeve pin and stepped pin are inserted into the mold, and Figure 2 shows the thermosetting resin in the mold. Figure 3 shows the state in which the sleeve pin is retracted after the sleeve pin has been injected.
Moreover, FIG. 4 shows the state in which the roof has been removed. Fig. 5 is a perspective view of a row of products molded by the method of the present invention, Fig. 6 is a sectional view taken along the line ■-■ in Fig. 5, and Fig. 7 is a perspective view of another product. FIG. 8 is a sectional view taken along the line ■-■ in FIG. 7. 7...Thermosetting resin, 9...Thermoplastic resin, 10.
・Empty space for self-tapping. Applicant's Representative Patent Attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Procedural Amendment, Sゎ6ρ, 3. 4e Manabu Shiga, Commissioner of the Patent Office1, Indication of the case, Japanese Patent Application No. 1983-0126542, Name of the invention, Method for manufacturing resin molded products, 3, Person making the amendment, Relationship to the case, Patent applicant Sanshin Kogyo Co., Ltd.4, Agent 5, voluntary amendment 7, content of amendment (1) Chuon, page 2, line 2 “...5 kf/-
Insert the two characters ``degree'' next to J. (2) In the 4th line of the same page, insert the 9 characters ``There is a risk of causing...'' next to ``Defective product.'' (3) Delete the 3 characters "next" in the 5th line of the same page. (4) On the same page, insert the five characters ``may be'' next to ``...will disappear.'' (5) On page 4, line 1, "Sheracon" is corrected to "polyacedal."

Claims (1)

[Claims] Resin molding that consists of the steps of forming a pilot hole that will be the outer diameter of the self-tapping part when molding a molded product made of thermosetting resin, and molding a thermoplastic resin that has a cavity for a tap inside the pilot hole. product manufacturing method.