JPS63254017A - Manufacture of plastic molded article having insert with male screw - Google Patents

Abstract

PURPOSE:To prevent the collapse of the crest of a screw thread as well as the generation of a flaw on the surface of a mold, by a method wherein an elastic body, attached to a male screw, is arranged on the surface of a cavity and the position of an insert is fixed, thereafter, reactive liquid material is cast and molded. CONSTITUTION:When a tubular elastic body 32 is attached to the male screw 30 of an insert 42, the elastic body 32 is expanded slightly and the neck of the male screw 30 is sealed perfectly. This elastic body 32 is fitted forcibly into a hole 38, provided on the surface 36 of a cavity of molding mold. According to this constitution, the elastic body 32 is tightened from the outside thereof and is adhered to the outer periphery of the male screw 30. Next, reactive liquid material is cast into the cavity 24 of the molding mold. Since the neck of the male screw 30 is sealed by the elastic body 32, the reactive liquid material will never ingress into a gap between the outer peripheral surface of the male screw 30 and the inner surface of the elastic body and the inserted part 40 of the insert 42, equipped with the male screw, is buried into an fixed to the molded form without clogging the thread of the screw. When the male screw 30 is removed from the elastic body 32 after releasing it from a mold, a plastic molded form, having the insert equipped with the male screw, may be obtained.

Description

Detailed Description of the Invention (Field of Industrial Application) This invention provides a method for embedding a male-threaded insert by installing a male-threaded insert in a cavity and injecting a reactive liquid raw material into the cavity. made of plastic. The present invention relates to a method of manufacturing a molded article.

(Prior Art) Automotive parts such as spoilers, instrumentation panels, and other plastic molded products often have male screws embedded and fixed therein in order to attach the plastic molded products to automobiles and the like.

The production of such plastic molded parts with embedded and fixed male screws is carried out in the usual manner. First, the 6th
As shown in the figure, a male threaded insert 14, in which a male thread 12 is fixed to an insert 10 by welding or the like, is placed in a mold 1.
The male screw 10 is inserted into the hole 20 provided in the cavity surface 18 of the device 6, and the device is fixed at a predetermined position. Then the seventh
As shown in the figure, a reactive liquid raw material, such as a urethane raw material, is injected into the cavity 24 of the mold 16.22 in which the male threaded insert 14 is installed, and a plastic molded product in which the insert 10 is embedded is manufactured. . Note that the six directions of arrows are the mold opening directions.

However, since the male thread 12 is threaded spirally from one end to the other end of the outer circumferential surface, no matter how much the alignment between the outer circumferential surface of the male thread 12 and the inner circumferential surface of the hole 20 is improved, the cavity 24 The reactive liquid raw material injected into the male thread 12
It will get inside the thread of the screw.

Therefore, it is necessary to remove the resin that has solidified within the threads after molding the product. Furthermore, since it is difficult to completely remove the dirt, there is a risk that the nut may not be fully tightened when the product is installed. Furthermore, when taking out the product from the mold 16 or removing the resin, there is a risk of crushing the threads or damaging the cavity surface.

(Problems to be Solved by the Invention) This invention solves a problem that conventional manufacturing methods have, namely, when manufacturing a plastic molded product having a male threaded insert, the threads of the male screw become clogged with resin. This is to solve the various problems mentioned above.

(Means for Solving the Problems) The present invention provides a plastic product in which a male-threaded insert is installed in a cavity, and a reactive liquid raw material is injected into the cavity, thereby embedding the insert in a molded product. In the method for manufacturing a molded product, a cylindrical elastic body is attached to a male screw in advance, and the insert is fixed in position by installing the elastic body at a predetermined position on a cavity surface,
This method is characterized in that the reactive liquid raw material is then injection molded.

(Function) In this invention, the male thread is covered with a cylindrical elastic body and the male threaded insert is installed in the cavity. It will be completely sealed. Therefore, the reactive liquid raw material injected into the cavity cannot enter between the outer circumferential surface of the male thread and the inner circumferential surface of the elastic body, and a cavity-shaped plastic molded product is formed without clogging the threads. The plastic molded product has a male threaded insert embedded and fixed therein, and a series of manufacturing operations is completed by removing the elastic body from the male thread after demolding. This eliminates the need for the conventional work of removing resin clogging the screw threads, and also solves the aforementioned various problems caused by resin clogging the screw threads.

(Example) The present invention will be described below based on an example and with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which a male thread 3
3 is a cross-sectional view showing a case where a cylindrical elastic body 32 is attached to a mold 0 and the elastic body 32 is inserted into a hole 38 provided in a cavity surface 36 of a mold 34. FIG.

Preferably, the male screw does not have a thread over a predetermined length of the neck, like the male screw 31 shown in FIG. 3, than the male thread 30 shown in FIG. 1, which has a thread all the way to the neck.

If the neck does not have a thread over a predetermined length, the elastic body 32
This is because when it is applied, its elasticity allows it to completely adhere to the outer circumferential surface of the neck, thereby further improving the sealing performance of the neck.

Note that the male thread 30 is fixed to a metal insert 40 by welding or the like, and is used as a male threaded insert 42. The metal insert 40 is adapted to the purpose, shape, etc. of the plastic molded product, and has the function of fixing the male screw 30 within the molded product, as well as maintaining the shape of the molded product and increasing the rigidity. It is.

The cylindrical elastic body 32 is made of an elastic body such as rubber and has a male thread 30.
It has a hole 44 that allows it to be tightly attached.

Moreover, the elastic body 32 is shown in FIG.
Although the shape may be either round or rectangular as shown in (b), the diameter a of the opening of the hole 44, which serves as the male screw insertion port, is made smaller than the outer diameter of the male screw 30, so that it has elasticity when attached. Preferably, the body 32 tightens the neck of the male thread 30 so that it is in close contact with the neck, so that the core can be completely sealed by the elastic body 32. In this case, if the male thread is threaded to the neck, the thread will bite into the elastic body 32.

The mold 34 is a split mold, and has a cavity surface 36 provided with a hanging hole 38 into which the cylindrical elastic body 32 is inserted. Further, the hole 38 may be replaced by a groove shape.

This hole 38 or groove has a dimension slightly smaller than the outer shape of the cylindrical elastic body 32, so that when the elastic body 32 is fitted into the hole 38 etc., the elastic body 32 is removed from the outer shape by the inner surface of the hole 38 etc. It is preferable to tighten the screw so that it is in close contact with the outer circumferential surface of the male thread. Also, as shown in Figure 4, one side of the split type 4
Insert the cylindrical elastic body 32 into the groove 48 provided on the dividing surface of No. 6,
The elastic body 32 may be sandwiched between the other split molds 50. Incidentally, in the split molds 46 and 50 shown in FIG. 4, the male threads 31 are installed in a direction different from the mold opening direction.

Furthermore, in the split molds 52 and 54 shown in FIG. 5, the male screws 31 are also provided upright in a direction different from the mold opening direction. 33 is a cylindrical elastic body, and 39 is a hole provided in the cavity surface.

The cylindrical elastic body 32 is attached to the male thread 30 of the male threaded insert 42 thus formed. When the elastic body 32 is attached, the elastic body 32 expands slightly, and the resulting elastic restoring force brings the opening of the elastic body 32 into close contact with the neck of the male screw 30. As a result, the neck of the male thread 30 is completely sealed by the elastic body 32.

This cylindrical elastic body 32 is press-fitted into a hole 38 provided in a cavity surface 36 of a mold as shown in a chain line as shown in FIG. As a result, the elastic body 32 is tightened from the outside by the inner surface of the hole, and is further brought into close contact with the outer periphery of the male screw 30. Hey, number 4
Similarly, when clamping with the split mold 46.50 shown in the figure, the elastic body 3
2 is in close contact with the outer peripheral surface of the male screw 31.

Next, the mold cavity (corresponds to 24 in Fig. 7).
A reactive liquid raw material such as a urethane raw material is injected into the reactor. Since the neck of the male screw 30 is sealed by the cylindrical elastic body 32, the injected reactive liquid raw material does not enter between the outer circumferential surface of the male screw 30 and the inner surface of the elastic body, and flows into the cavity without clogging the screw thread. It becomes a shaped plastic molded product.

The resulting plastic molded product has the insert 40 portion of the male threaded insert 42 embedded and fixed within the molded product. After removing the molded product from the mold, the cylindrical elastic body 32 is removed from the male thread 30, resulting in a plastic molded product having a desired male threaded insert. The removed cylindrical elastic body is used repeatedly in manufacturing the plastic molded product.

(Effects of the Invention) The present invention covers a male thread of a male threaded insert with a cylindrical elastic body, places the elastic body at a predetermined position on a cavity surface, and injects a reactive liquid raw material into the cavity. Because it manufactures plastic molded products, it was able to achieve the following effects.

In other words, it is possible to prevent the threads of male screws from becoming clogged with resin, thereby eliminating the need to remove the resin (paris), and preventing the threads from collapsing and molding, which tend to occur when demolding products and removing pars. This makes it possible to prevent surface scratches from occurring.

In addition, even in high-pressure injection molding such as polyurethane RIM molding where liquid raw materials can easily enter even the smallest gaps, male threaded inserts can be embedded and fixed within the molded product without clogging the threads with resin. It has become.

Furthermore, even if the male screw is erected in a direction different from the direction in which the mold opens, it is possible to mold the product without any problem.

Furthermore, since the cylindrical elastic body can be used repeatedly, the use of the elastic body does not lead to an increase in cost.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention in which a cylindrical elastic body is attached to a male thread and the elastic body is installed on the cavity surface, and FIGS. 2(A) and 2(B) is a plan view of a cylindrical elastic body, FIG. 3 is a sectional view illustrating a male threaded insert in this inventive example, FIGS. 4 and 5 are sectional views each showing still another example of the present invention, and FIG. Figure 6 is a cross-sectional view of a conventional male threaded insert when the cavity surface is installed.
FIG. 7 is a sectional view showing the conventional manufacturing process. 30 male thread, 32- cylindrical elastic body, 36 cavity surface, 38 hole, 40 insert, 42 male threaded insert, 44 hole Patent applicant Inoue MBC Co., Ltd. Figure 2 (In Figure 2 (0) Figure 4 f45 diagram

Claims (4)

[Claims] (1) In a method of manufacturing a plastic molded product in which an insert with a male thread is placed in a cavity and a reactive liquid raw material is injected into the cavity, the insert is embedded in the molded product. It has a male-threaded insert characterized by being coated with a cylindrical elastic body, fixing the insert in position by placing the elastic body at a predetermined position on the cavity surface, and then performing injection molding of a reactive liquid raw material. Method of manufacturing plastic molded products. (2) The method for manufacturing a plastic molded product having a male threaded insert as set forth in claim 1, wherein the male thread insertion opening of the cylindrical elastic body is smaller than the male thread diameter. (3) A method for manufacturing a plastic molded product having a male threaded insert according to claim 1 or 2, in which the neck of the male thread does not have a predetermined thread length. (4) A method for manufacturing a plastic molded product having a male threaded insert according to any one of claims 1 to 3, in which a cylindrical elastic body attached to a male thread is sandwiched between split molds. .