JPS6186241A - Manufacture of fiber-reinforced plastics screwlike-molded material - Google Patents

Abstract

PURPOSE:To obtain the title molded material which is superior in durability such as fatigue resistance characteristics, by a method wherein a thread is formed through rolling process by controlling a thread forming sphere of a molding material made of thermoplastic resin, in which reinforcing fiber has been made to disperse, and a rolling die at a specific temperature. CONSTITUTION:Thermoplastic resin such as polyamide resin and reinforcing fiber such as glass fiber are melted and mixed by an extrusion molding machine with each other, and a molding material to be obtained by making the foregoing reinforced fiber disperse uniformly within the thermopolastic resin is formed. Then the target molded material is obtained by forming a thread by applying rolling process to a thread forming sphere of a surface layer part of a molding material after more than a part of the thread forming sphere of the surface layer part of the molding material has been heated at the temperature of more than the fusion point of the foregoing thermoplastic resin and a rolling die has been controlled to the temperature of less than the fusion point of the thermoplastic resin.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for rolling a plastic thread-shaped molded article such as a plastic bolt, and particularly a method for rolling a plastic material highly reinforced with one reinforcing fiber. It relates to a method performed by processing.

(Prior Art) As the thread-shaped molded body 2, for example, a bolt, a metal bolt is conventionally known. This is manufactured using the rolling method, which has the fastest production speed for thread processing.

Although metal bolts are made with such high productivity, they have the fatal disadvantage of being heavy and prone to rust.

In contrast, plastic bolts, which are lightweight and have excellent corrosion resistance, have already been put into practical use.

However, plastic materials to which rolling can be applied are limited to non-fiber reinforced plastic materials such as hard vinyl chloride resin. Fiber-reinforced plastic materials have poor plastic deformability due to their high strength.

This is because it is impossible to form threaded ridges by rolling, which requires plastic deformability. Even if this is forcibly rolled, the threads will not form a triangular shape, and the top of the triangle will become two threads, or cracks will occur in the threads. Therefore 1
It has low strength and cannot be used as a screw. Bolts obtained by rolling a non-fiber reinforced plastic material are inferior in one strength. Its tensile strength is at most 4 to 5 kg/a
m2, it cannot withstand use as a bolt that requires a strong fastening force.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned problems of the prior art,
The purpose is to provide a method for rolling a plastic screw-shaped molded article that is lightweight, has corrosion resistance, chemical resistance, electrical insulation properties, and is highly reinforced with reinforcing fibers. Another object of the present invention is to provide a method for manufacturing a plastic thread-shaped molded body having high strength and durability by rolling, which is the most economical method for threading.

(Means for Solving the Problems) The method for rolling a fiber-reinforced plastic screw-shaped molded article of the present invention is characterized in that at least the surface layer of the molding material is made of a thermoplastic resin in which reinforcing fibers are dispersed. When forming a thread with a rolling die, at least a part of the thread forming area of the surface layer is heated to a temperature higher than the melting point of the core thermoplastic resin, and the thread rolling die is heated to a temperature higher than the melting point of the core thermoplastic resin. The above-mentioned object is achieved by performing rolling processing while controlling the temperature to be below the melting point. The term "thread-shaped molded body" as used in the present invention refers to a molded body having a thread such as a bolt or a nut.

Examples of reinforcing fibers include glass fiber.

There are inorganic fibers such as carbon fiber, boron fiber, silicon carbide fiber, and potassium titanate fiber; and organic fibers such as aramid fiber. It is also possible to use a mixture of two or more of these fibers. There is no particular restriction on the length of the fibers, as long as they can be dispersed in the thermoplastic resin molded into the molding material. These reinforcing fibers are melt-mixed with a thermoplastic resin using a kneading means such as an extruder, and are uniformly dispersed in the resin.

This reinforcing fiber is 10 to 40% by volume, preferably 15 to 40% by volume.
It is included in the range of 35% by volume. If the fiber content is too low, a high-strength plastic screw-shaped molded article cannot be obtained. If the fiber content is too high, it will become brittle and the reinforcing effect will decrease.

Examples of thermoplastic resins include polyamide.

Polyethylene terephthalate, polybutylene terephthalate, polyacetal 1 polysulfone.

Polyphenylene sulfide, polyetheretherketone, polyimide, etc. are used. Needless to say, there is no need to be limited to this.

These resins may be mixed with various additives such as fillers, processing agents for improving adhesion to fibers, flame retardants, and antioxidants, if necessary.

In the molding material used in the present invention, at least the surface layer portion subjected to the rolling JJO process is composed of a thermoplastic resin in which the reinforcing fibers described above are dispersed. For example, the center part of a cylindrical material used when manufacturing bolts may have the same structure as the surface part, but it is a core material made of a high-strength metal material such as iron, a fiber-reinforced thermosetting resin material, etc. Good too.

When a core material is used, the surface of the core material may be provided with irregularities or grooves to improve bondability with the thermoplastic resin.

For example, when the above-mentioned cylindrical element +A is subjected to rolling processing by the method of the present invention, at least a part of the thread forming area of the surface layer is formed by the melting point base of the thermoplastic resin constituting the cylindrical material. heated to temperature.

Here, the term "thread forming area" refers to a portion where a thread is to be formed. The surface layer portion heated to a temperature above the melting point is a region radially extending from the surface layer surface of the 9-cylindrical material to a depth of 1720 to 1 times the height of the ridge to be formed. If it is less than 1720 times, the reinforcing fibers will peel off from the thermoplastic resin during rolling, and the degree of adhesion at the interface between the reinforcing fibers and the thermoplastic resin at the deformed portion due to rolling will deteriorate. Therefore, the resulting rod-shaped molded product has poor durability. If it exceeds 1, the cylindrical material itself will be greatly deformed during rolling, making it impossible to form good threads. The surface layer portion is preferably heated to a melting point of the thermoplastic resin of 3 or more and 100° C. or less (the melting point of the thermoplastic resin plus 100° C.). At excessively high temperatures, it is difficult to heat only the surface layer of the cylindrical material. To heat the surface layer of the cylindrical material, there are methods such as heating the cylindrical material with hot air controlled at a predetermined temperature; immersing the cylindrical material in a liquid controlled at a predetermined temperature for a short time; etc. will be adopted.

The temperature of the rolling die during rolling is controlled at +11" below the melting point of the thermoplastic resin that makes up the cylindrical material. If the temperature exceeds the melting point, a thread with a normal shape will not be formed. The temperature is not particularly limited as long as it is below the melting point, but it is preferable to keep it at a constant temperature.When heating the rolling die, a method such as incorporating a heater in the die is used.The rolling method is particularly It is not necessary to use a rolling machine such as a round die rolling machine or a flat die rolling machine that is commonly used for thread forming processing of metal thread.

(Function) According to the method for producing a thread-shaped molded body of the present invention, at least a part of the thread-shaped bottom region of the surface layer portion of the molding material is heated to a temperature higher than the melting point of the thermoplastic resin constituting the molding material.
The plastic deformability of the heated surface layer improves, making thread processing possible. Good results can also be achieved by rolling while keeping the molding material or rolling die at an appropriate temperature below the melting point of the thermoplastic resin, or by contacting a heating medium at an appropriate temperature below the melting point of the thermoplastic resin during rolling. Although it is possible to obtain a high-strength screw-shaped molded article having a threaded shape, in such a method, the reinforcing fibers peel off from the thermoplastic resin at the deformed portions due to rolling during rolling. Therefore, the degree of adhesion at the interface between the 9 reinforcing fiber and the thermoplastic resin is poor. Although such a thread-shaped molded body has good initial strength, it is inferior in durability such as fatigue resistance and creep resistance. In the method of the present invention, the surface layer of the molding material is heated above the melting point of the thermoplastic resin and rolled, so the reinforcing fibers do not peel off from the thermoplastic resin. 1. For example, it can withstand long-term vibration stress and has excellent durability such as fatigue resistance and creep resistance.

(Example) The present invention will be described below with reference to Examples.

Example 1 (A) Preparation of cylindrical material: First, polyamide resin (Amiran nylon 66 prepared by Toshiba; melting point 265°C) and glass fiber with a diameter of 9 μm and a diameter of 6 mm were mixed in a volume ratio of 70:30.
The mixture was triblended using an extrusion molding machine to form a round bar with a diameter of 9 cranes. Next, this was cut into a length of 20 cm to obtain 11 cylindrical materials.

(B) Preparation of plastic bolt: One end of the cylindrical material obtained in section (A) was placed in a hot air oven controlled at 300° C. while rotating, and heated for 6 seconds.

This was taken out and MIO, Pl, 5 controlled at 220°C.
Rolling was quickly carried out using a three-roll rolling machine that forms a thread. The other end of the cylindrical material was rolled in the same manner, and a threaded ridge of 3 cffl was formed at each end of the M.
Obtained 10 IO bolts.

The following test was conducted to determine the depth of the surface layer of the cylindrical material heated to a temperature above its melting point. The cylindrical material obtained in section (A) was cut at a position 1 cm from one end of the cylindrical material. An adhesive mixed with a paint that irreversibly changes color at 270° C. was prepared, and the cylindrical material whose ends had been cut was glued back together using this adhesive. This cylindrical material was placed in a hot air oven under the same conditions as above. After this was cooled, the cross section of the part bonded with the adhesive was observed, and it was found that the discolored part extended from the surface layer of the cylindrical material to a depth of approximately 0.8111 mm in the radial direction.

(C) Bolt performance test: Tensile strength was measured using five of the bolts obtained in section (B), and fatigue cycle was measured using the remaining five bolts. The results are shown in the table below. These were measured by the following test method, and the average value of the measurements for five bolts was determined.

Tensile Strength MIO size screws were attached to both ends of the bolt, and the breaking strength was measured according to the method of JIS B 1051.

Fatigue Cycle M10 size nuts were attached to both ends of the bolt, and a tensile load of 500 kg was applied. Furthermore, a vibration load of ±200 kg was applied, and the number of vibrations until the bolt broke was measured.

DAIJIKAI 1 (A) Preparation of cylindrical material: Example 1 Same as section (A).

(B) Preparation of plastic bolts Same as Example 1 (B) except that the temperature of the two rolling dies was 150°C.

(C) Bolt performance test: Example 1 Same as section (C).

Method - Treatment ILβ- (Δ) Preparation of cylindrical material 2 Example 1 Same as section (A).

(B) Preparation of plastic bolts: Bolts were prepared in the same manner as in Example 1 (B) except that the hot air oven was controlled at 330°C and the heating time for the two cylindrical materials was 4 seconds. The discolored portion of the adhesive was an area approximately 1.1 fl deep in the radial direction from the surface layer of the cylindrical material.

(C) Performance test of Pol 1-; Example 1 Same as section (C).

Example 4 (A) Preparation of cylindrical material: Same as Example 1 (A).

(B) Preparation of plastic bolt: A bolt was prepared in the same manner as in Example 1 (B) except that the heating time of the cylindrical material was 2 seconds. The discolored portion of the adhesive was in an area of about 0.3 mm in the radial direction from the surface layer of the cylindrical material.

(C) Bolt performance test: Example 1 Same as section (C).

Comparison (A) Preparation of cylindrical material: Example 1 Same as section (A).

(B) Preparation of plastic bolts: Bolts were prepared in the same manner as in Example 1 (B) except that the hot air oven was controlled at 240°C. No discoloration of the adhesive was observed.

(C) Bolt performance test: Example 1 Same as section (C).

(A) Preparation of cylindrical material: Example 1 Same as section (A).

(B) Preparation of plastic bolts with two rolling dies 270
A bolt was prepared in the same manner as in Section (B) of Example 1, except that the temperature was controlled at .degree.

(C) Bolt performance test; Example 1 Same as section (C).

Comparative Example 3 (A) Preparation of cylindrical material: Same as Example 1 (A).

(B) Preparation of plastic bolt 2. A bolt was prepared in the same manner as in Example 1 (B) except that the heating time of the cylindrical material was 20 seconds. The discolored portion of the adhesive was in an area of approximately 2.5 mm in the radial direction from the surface layer of the cylindrical material.

(C) Bolt performance test: Example 1 Same as section (C).

” ” 巳中交 1 多 1 (A) Preparation of cylindrical material: Example 1 Same as section (A).

(B) Preparation of plastic bolt 2 A bolt was prepared in the same manner as in Example 1 (B) except that the cylindrical material was not heated.

(C) Bolt performance test; Example 1 Same as section (C).

(Effects of the Invention) According to the present invention, it is extremely easy to perform thread forming by rolling on a plastic molding material highly reinforced with one reinforcing fiber.

Thread forming by rolling increases productivity, so thread-shaped molded bodies such as bolts can be produced economically.

Moreover, the thread shape of the resulting plastic screw-shaped molded product is good, and the top of the thread does not form two threads, or cracks or splits do not occur. The thread-shaped molded body has high strength and excellent durability such as fatigue resistance and creep resistance.

Furthermore, it has all the characteristics inherent to plastic materials, such as being lightweight and highly corrosion resistant. The thread-shaped molded product obtained by the method of the present invention can be used in a wide range of fields such as structural fastening.

that's all

Claims (1)

[Claims] 1. When forming a thread using a rolling die in the surface layer of a molded material, at least the surface layer of which is composed of a thermoplastic resin in which reinforcing fibers are dispersed, at least a part of the thread forming area of the surface layer. of a fiber-reinforced plastic screw-shaped molded article, which comprises heating the thermoplastic resin to a temperature higher than the melting point of the thermoplastic resin and controlling a rolling die to a temperature lower than the melting point of the thermoplastic resin to perform rolling processing. Production method.