JPS61197809A - Screw part made of plastic and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a double-structured plastic screw component having a plastic core material and a method for manufacturing the same.

(Conventional Techniques) Recently, screw parts used in electrical equipment and the like have been made of plastic instead of metal.

This is because it is lighter, chemically stable, and has electrical insulation properties than the glass-1 group.

In terms of strength, cost, and dimensional stability, this type of plastic screw part is made of continuous glass fiber-filled plastic (k' RP) with high mechanical strength for only the surface layer of the screw thread. The interior is made of inexpensive polyester plastic material, and nine types are often used.

Such a double structure plastic screw part is manufactured by the following method. That is, a long rod-shaped polyester plastic is used as a core material, and epoxy plastic or acrylic plastic containing continuous glass fibers is temporarily laminated on the outside, and screw threads are machined into this glass coating layer to form screws. After making a stick,
After cutting this into a predetermined length, a screw head is fitted and fixed to one end to obtain a plastic screw component.

(Problem to be Solved by the Invention) However, when plastic threaded parts are manufactured in this way, when threading is performed using a lathe, etc., the leakage is supported and fixed, and the threaded rod is bent. Therefore, the processing accuracy of the product is poor due to the thread cutting process. Moreover, in this case, since the continuous glass fibers reinforcing the outer plastic are cut with a cutting tool, the thread cutting efficiency is as low as about 30 minutes/meter, and the tensile strength is extremely poor. Furthermore, after producing the threaded rod, the threaded rod must be cut into pieces and the screw head must be fitted and fixed, resulting in a problem that the number of steps increases.

The present invention was made in view of these problems, and its purpose is to provide a plastic screw part and a manufacturing method thereof that can improve quality and productivity by eliminating machining. There is a particular thing.

(Tth means for solving the problem) For this reason, the screw parts of the present invention have a thermoplastic glass material containing glass powder laminated on the outer periphery of a plastic core material, and the outer part of the screw head and the screw shaft are laminated. and an outer portion thereof are integrally formed of the glass powder-containing plastic laminate. Therefore, in the method of the present invention, an injection molding method is adopted to form the screw head and the outer portion of the screw shaft. That is,
The mold according to the present invention has a product shape surface that corresponds to the external shape of the screw head and screw shaft, and first, a plastic core material that will become an insert is placed at a predetermined position in the mold. Support both ends and secure. Next, after tightening, a heated and melted thermoplastic material containing glass powder is injected into the space formed by the core material and the mold. Thereafter, when the plastic material is cooled and hardened, the screw head and the outer portion of the screw shaft are integrally molded to obtain a double-layered plastic screw component.

The plastic core material in the present invention is made in advance to have a predetermined size and shape, and its cross-sectional shape is limited to a circle, but a nine-polygon shape similar to this is also possible. Materials for the core material include inexpensive polyester resin, vinyl chloride resin, polyethylene, polycarbonate, etc. 1. If the screw has a long shaft and mechanical strength is particularly required, it may be reinforced with glass fiber. Plastic (FP) may be used as the core material.

Friend, polyamide (nylon 6
, nylon 66, nylon 11, nylon 12, and aromatic nylon. ), polyacetal, polystyrene, high density polyethylene, polyzolopyrene, ABS1A8. Examples include polycarbonate and polybutylene terephthalate. The reinforcing glass powder mixed therein generally has a thickness of 3 to 20 microns, and its shape is not particularly limited, and may be bead-like or string-like. The content ratio of glass powder to thermoplastic is in the range of 20 to 50 mo. The reason why glass powder is used as the reinforcing material is that it can be easily packed into the screw threads and a high reinforcing effect can be expected.

(Function) Therefore, according to the screw component and the manufacturing method thereof of the present invention, the plastic laminate containing glass powder is integrally molded on the functional part outside the core material, so that the outside of the screw head and screw shaft is It can be formed at once with high processing accuracy, eliminating the need for thread cutting using a lathe, etc., and also eliminating the need for post-processing, making it possible to efficiently produce high-strength plastic screw parts.

(Example) Specific examples of the present invention will be described below. First, to explain the plastic bolt (screw part) manufactured by the method of the present invention, as shown in Fig. 1, a rod-shaped core material 2 made of polyester plastic is embedded inside the bolt l. Here, the core material 2 has a circular cross-sectional shape, but it may have a large number of grooves in the axial direction on its outer circumferential surface as shown in FIG. 2, or a cross-sectional shape as shown in FIG. The bolt may have a polygonal shape similar to a circle, or may have a larger diameter in a stepped manner on the bolt head side, as shown in FIG.

The outer portion of the core material 2 of this bolt 1 is made of polyamide (for example, nylon 6) 3 reinforced with glass powder, and the content ratio of the glass powder to the polyamide 3 is 45 to 50%.

Next, a method for manufacturing the plastic bolt 1 having the above structure will be described. As shown in FIG. It is shaped according to the shape, and this fixed Ml
A core material 2 of a predetermined length is set as an insert in i4.

At that time, the core material 2 is connected to the bold pin 5 provided on the fixed mold 4.
5 to hold both axial ends and fix in place.

After the core material 2 is set at a predetermined position within the fixed mold 4, a movable wheel (not shown) having the same product shape as the fixed mold 4 is clamped. Thereafter, as shown in FIG. 6, molten polyamide 3 mixed with reinforcing glass powder is injected under high pressure into the space inside the mold. The polyamide 3 is then solidified while being kept under pressure for a required period of time.

Once polyamide 3 has solidified, the pressure is removed and the mixture is cooled and hardened.
The movable mold is opened and the 11 fat molded product 1 is taken out of the fixed mold 4.

The thus obtained molded product 1 is a resin bolt 1 in which the outer surface of the bolt head and bolt shaft is made of polyamide 3 containing glass powder, and has a core material 2 inside. It has high mechanical strength, excellent wear resistance and self-lubricating properties, and has an extremely smooth surface.

In addition, in the embodiment, the core material 2 may be reinforced with long glass fibers if necessary.

It goes without saying that the present invention can be applied not only to the method of manufacturing hexagon bolts but also to methods of manufacturing machine screws, set screws, wood screws, eye bolts, foundation bolts, etc.

(Effect of the invention) According to the method for manufacturing a plastic screw component of the present invention,
Plastic containing glass powder is formed by injection molding on the outside of the screw head and screw shaft, eliminating the need for thread cutting using a lathe, etc., so the machining accuracy of the screw part in particular is not as high as before, and the material yield is also reduced. will improve. Furthermore, the threaded rod cutting process and screw head fixing process that were conventionally necessary are eliminated, and productivity per unit time is improved.

Furthermore, the screw parts obtained by the present invention have improved dimensional stability compared to conventional ones, guarantee uniform quality, and are suitable for mass production. In addition, since the glass powder used as a reinforcing material is fine, it easily penetrates into the screw threads and has a large reinforcing effect.

Therefore, the mechanical strength, particularly the impact resistance, of the threaded part is significantly improved compared to conventional threaded parts.

[Brief explanation of drawings]

1 to 6 show an embodiment of the present invention,
FIG. 1 is a partially cutaway perspective view of a bolt manufactured by the method of the present invention, and FIGS. 2 and 3 are A-A@ showing a modification of the core material of the bolt shown in FIG. 4 is a perspective view showing a modified example of the core material, FIG. 5 is a sectional view showing a fixed mold according to this embodiment, and FIG. It is a sectional view showing a state. 1... Bolt (screw parts) 2... Core material 3... Polyamide 4... Fixed type.

Claims (2)

[Claims] (1) A plastic screw component characterized in that a thermoplastic plastic material containing glass powder is laminated on the outer periphery of a plastic core material to integrally form the screw head and the outer portion of the screw shaft. (2) A plastic core material that will become an insert is supported and fixed in a mold that has a product shape surface that corresponds to the screw head and screw shaft, and after the mold is closed, heat containing glass powder is applied to the outer periphery of the core material. A method of manufacturing a plastic screw part, characterized by injecting and solidifying a plastic material.