JPS60201933A - Manufacture of plastic screw-shaped molding - Google Patents

Abstract

PURPOSE:To improve corrosion resistance, etc. by molding a plastic material in which a specific quantity of reinforcing fibers are added to a specific polyamide resin, manufacturing a columnar blank material, in which reinforcing fibers are orientated in the long axis direction, and forming a thread shaped by rolling the columnar blank material. CONSTITUTION:Not less than 15pts.vol. reinforcing fibers are added to a 100pts.vol. polyamide group resin containing at least one kind of nylon 6, nylon 6,6 and aromatic nylon at the rate of 70-95wt% and nylon 12 at the rate of 5-30wt%, thus preparing a plastic material. The plastic material is molded by an extrusion molding machine, etc., thus preparing a columnar blank material in which reinforced fibers are orientated in the long axis direction. The columnar blank material is rolled to form a thread, thus obtaining a screw-shaped molding. A two-roll rolling machine, etc. normally used for the thread molding machining of a metallic screw are employed for a rolling method.

Description

[Detailed description of the invention] (Technical field) The present invention relates to a method for manufacturing a plastic screw-shaped molded body.

In particular, the present invention relates to a method for threading a plastic material highly reinforced with double-reinforced fibers by rolling.

(Prior Art) Metal bolts have been known as bolts, which are one type of thread-shaped molded bodies. This is manufactured using the rolling method, which has the fastest production speed. Although metal bolts are made with such high productivity, they are said to be heavy and prone to rust.

It has a fatal flaw. In contrast, bolts are manufactured using plastics that are lightweight and have excellent corrosion resistance. For example, it can be obtained by injection molding of thermoplastic resins such as vinyl chloride and polycarbonate.

Such bolts have low strength (they can only be used for decorative purposes, etc.).Japanese Patent Publication No. 4B-9477 discloses a fiber-reinforced plastic bolt that is made of thermosetting resin but contains reinforcing fibers such as glass. There is.

However, the material of the bolt disclosed herein is a unidirectionally reinforced material, and does not have sufficient strength as a bolt subjected to multiaxial stress. Since threads are formed in this bolt by cutting, the two reinforcing fibers are cut and a notch effect occurs in the threads, making it impossible to obtain sufficient screw strength.

(Object of the Invention) An object of the present invention is to provide a method for producing a plastic screw-shaped molded article that is lightweight, has corrosion resistance, chemical resistance, and 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 that has high fastening strength, excellent impact resistance, and is less prone to brittle fracture. Still another object of the present invention is to provide a method for manufacturing a plastic screw-shaped molded article whose dimensions do not change due to ambient humidity and whose strength does not decrease over time. Still another object of the present invention is to provide a method for producing a high-strength plastic screw-shaped molded body by rolling, which is the most economical method of threading.

(Structure of the Invention) The method for producing a plastic screw-shaped molded article of the present invention includes 70 to 95% by weight of at least one of nylon 6, nylon 6/6 and aromatic nylon, and 5 to 30% by weight of nylon 12. Polyamide resin contained in proportion: 10
A step of obtaining a plastic material by adding 15 parts by volume or more of reinforcing fibers to 0 parts by volume, a step of molding the plastic material to obtain a cylindrical material in which the reinforcing fibers are oriented in the longitudinal direction;
and a step of rolling the cylindrical material to form a threaded pile.

This achieves the above objective.

Since the polyamide resin used in the present invention contains nylon 12, the water absorption of the resin is suppressed.

Provides plastic deformability. Moreover, the strength of the resin itself increases. When the content (1) of nylon 12 is less than 5% by weight, the strength of the obtained bolt decreases due to water absorption, and even one dimension changes. It also lacks impact resistance, making it susceptible to brittle fracture due to single-head impact or diagonal tightening. Furthermore, it has poor plastic deformability.

Even after rolling, the threads do not form a normal triangular shape.
The top of the triangle becomes two peaks, or cracks occur in the threads. When the content of nylon 12 exceeds 30%, the strength of nylon 12 itself is low, so the strength of the resulting bolt is reduced as a whole. nylon 12
The content is preferably 15 to 20%. Prior to mixing reinforcing fibers, it is desirable to thoroughly knead the entire resin so that the nylon 12 is uniformly dispersed.

If the tik condition of nylon 12 is poor, it will be damaged by rolling.
The threads obtained do not have a normal shape and the strength of the obtained screw is low.

The reinforcing fibers mixed in the above resin include glass fiber,
Examples include carbon fiber. There is no particular restriction on the length of the fibers, as long as the resin can be uniformly dispersed in the desired cylindrical material when it is molded into the material.

Generally, 1 to 6111 fibers are suitable. The reinforcing fibers are contained in an amount of at least 15 parts by volume per 100 parts by volume of the resin. If it is too small, it will not be possible to obtain a bolt with high tensile strength, and if it is too large, not only will the workability of kneading and forming be reduced, but the reinforcing effect will also be reduced, making the bolt more susceptible to brittle fracture. The content of the reinforcing fibers is preferably 15 to 30 parts by volume per 100 parts by volume of the polyamide resin.
Department.

A plastic NA material containing the above resin and reinforcing fibers is molded into a cylindrical material by conventional extrusion molding or the like.

The reinforcing fibers are oriented in the long sleeve direction at least in the surface layer of the resulting cylindrical material. In injection molding, the flow rate of resin into a single cylindrical material mold is generally high, so that sufficient orientation of reinforcing fibers cannot be obtained. Furthermore, since the cross-sectional area of the gate is usually larger than the cross-sectional area of the cylindrical material into the mold, turbulence occurs in the flow of the molten plastic material near the cylindrical material mold.

Therefore, the desired orientation of one reinforcing fiber cannot be achieved sufficiently.

Therefore, in order to obtain a cylindrical material by injection molding, it is essential to make the gate area of the injection molding machine equal to or smaller than the cross-sectional area of the cylindrical material.

When the obtained cylindrical material is divided into two in the longitudinal direction and the cross section of the surface layer is observed under a microscope, it is necessary that the number of fibers oriented in the longitudinal direction accounts for the majority of the total fibers. When the fibers are oriented in the long axis direction in this way, when a thread is formed on this cylindrical material by rolling,
The fibers near the threads are oriented along the threads, resulting in a thread-shaped molded product with high strength.

The rolling method adopted for threading the thread-shaped molded product of the present invention does not need to be special, and a two-roll rolling machine that is commonly used for thread root shaping of metal screws is used.

A three-roll rolling machine, a flat die rolling machine, etc. can be used. It is preferable that the rolling speed be slightly faster than that for a metal thread-shaped molded body.

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

Fruit fat plate nylon 6/6 (manufactured by Toshi Co., Ltd.: Amiran C303
0) 90 parts by weight and nylon 12 (manufactured by Ube Chemical Co., Ltd.:
3035U) was melt-kneaded in advance and pelletized. 100 parts by weight (approximately 30% by volume) of glass fibers having a diameter of 13 μm and a length of 3 mm were added and kneaded, and this was injection molded to obtain a cylindrical material for a bolt.

This is rolled at room temperature using a rolling machine with three roll dies to form a threaded thread, with a diameter of 9 and a length of 50 as shown in Figure 1.
I then obtained MIO bolt 1 with a head thickness of 7.5 fins.

The thread of the bolt 1 obtained had a normal triangular shape.

Table 1 shows the ingredients contained in the plastic material used. The bending strength of the obtained cylindrical bolt material was measured, and the obtained bolt was subjected to a tensile test and a 4" wedge tensile test.Furthermore, a tensile test was performed after immersing it in water at 20°C for 3 days. I also observed how easy it was to enter the nuts.

The results are shown in Table 2. The 4° wedge tensile test is
A 4° wedge 2 as shown in FIG. 2 was applied to the bolt head 11 so that a diagonal tensile force was applied to the bolt 1 obtained, and a tensile load was applied to both ends of the bolt 1. The results of the tensile strength test after immersion in water are as follows: ◎ indicates that Nando's penetration is extremely good.

The mark Q indicates that the nut can be attached to the bolt without getting caught, and the mark X indicates that the nut cannot be attached.

The procedure was the same as in Example 1 except that 80 parts by weight of nylon 6.6 and 20 parts by weight of nylon 12 were used. The shape of the threads of the obtained bolt was similar to that of Example 1.

The procedure was the same as in Example 1 except that 60 parts by weight (approximately 20% by volume) of the charcoal-based glass fibers were used. The shape of the threads of the obtained bolt was similar to that of Example 1.

comparison and development 100 parts by weight of nylon 6.6 and a diameter of 13 μm.

100 parts by weight of glass fibers having a length of 3 mm were kneaded, and a cylindrical material similar to that of Example 1 was obtained by injection molding.

This was rolled in the same manner as in Example 1 to obtain a bolt.

The thread surface of the resulting bolt was not smooth. The top of the screw thread had two peaks.

The composition of the resin and the results of each test are shown in Tables 1 and 2 as in Example 1.

Comparison coal 1 60 parts by weight of nylon 6.6 and 40 parts by weight of nylon 12
The same as Example 1 except that parts by weight were used.

11) The threads of the bolts were the same as in Example 1.

4 piece 1 of the top The same composition as in Example 1 was injection molded into a mold having the shape of an MIO bolt to obtain a bolt without rolling. The threads of the obtained bolt were similar to those in Example 1. The composition of the resin and the results of each test are shown in Tables 1 and 2 as in Example 1.
Shown below.

Table 1 (blank below) As is clear from Tables 1 and 2, the addition of nylon 12 slightly lowers the strength of the cylindrical material. However, the strength of the bolt after rolling is actually higher than that without additives, and the thread root shape can be made normal. The strength after the 4° wedge tensile test and water resistance test is also stable. Bolts without the addition of nylon 12 expand due to water absorption, so it is difficult for the bolts to enter the bolt after being immersed in water.

(Effects of the Invention) According to the method of the present invention, in order to orient the reinforcing fibers in the length direction of the cylindrical material obtained by molding the plastic material containing nylon 12 and reinforcing fibers,
A thread-shaped molded body can be easily obtained by highly productive rolling process. The thread shape of the resulting wedge-shaped compact is good;
The top of the screw thread does not double or crack or split.

In addition, the thread-shaped molded body has high strength, high fastening force, low hygroscopicity, and no dimensional distortion due to moisture absorption. Furthermore, even if it is tightened diagonally, brittle fracture is unlikely to occur. Furthermore, it is lightweight and has all the characteristics inherent to plastic materials, such as corrosion resistance, chemical resistance, and electrical insulation.

[Brief explanation of drawings]

FIG. 1 is a front view showing an example of a plastic bolt obtained by the method of the present invention, and FIG. 2 is an explanatory view illustrating an example of a 4° wedge tensile test of this POL 1-. 1...Plastic bolt, 2...4° wedge. 11...Head. Applicant: Sekisui Chemical Co., Ltd. Figure 1 Figure 2

Claims (1)

[Scope of Claims] (1) 100 volumes of polyamide resin containing 70 to 95% by weight of at least one of nylon 6, nylon 6.6 and aromatic nylon and 5 to 30% by weight of nylon 12; A process of obtaining a plastic material by adding 15 parts or more of reinforcing fiber to 1 part. A method for manufacturing a plastic screw-shaped molded body, which includes a step of molding the plastic material to obtain a cylindrical material in which the reinforcing fibers are oriented in the longitudinal direction, and a step of rolling the cylindrical material to form a thread. .