JPH0463768B2 - - Google Patents

Description

[Detailed description of the invention]

(Technical Field) The present invention relates to a plastic thread-shaped molded body, and particularly to a plastic thread-shaped molded body highly reinforced with reinforcing fibers and a method for manufacturing the same. (Prior Art) Metal bolts have been known as thread-shaped molded bodies. This is manufactured using the rolling method, which has the fastest production speed for thread processing. Although metal bolts are manufactured with such high productivity, they have the fatal disadvantage of being heavy and prone to rust. On the other hand, plastic bolts that are lightweight and have excellent corrosion resistance are already in practical use. Special Public Service 1977
Publication No. 9477 discloses a fiber-reinforced plastic bolt that is made of a thermosetting resin but contains reinforcing fibers such as glass. 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 the threads of this bolt are formed by cutting, the reinforcing fibers are cut and a notch effect occurs in the threads, making it impossible to obtain sufficient thread strength.
There are also plastic bolts made by injection molding, but they have the disadvantage that they have low strength and the nuts tend to loosen, making it difficult to obtain sufficient fastening force. (Objective of the Invention) The object of the present invention is to provide a plastic screw-shaped molded article that is lightweight, has corrosion resistance, chemical resistance, and electrical insulation properties, is highly reinforced with reinforcing fibers, has high fastening force, and is resistant to loosening. The object of the present invention is to provide a manufacturing method thereof. Another object of the present invention is to provide a method for producing a high-strength plastic thread-shaped molded body by rolling, which is the most economical method for thread processing. (Structure of the Invention) The fiber-reinforced plastic screw-shaped molded article of the present invention includes:
60% of the numbers exist within ±5° in the major axis direction
The thermoplastic resin is composed of a thermoplastic resin containing short glass fibers which are oriented so as to occupy the same area as above, and whose end surfaces are exposed on the side surface of the screw thread.
Contains 20 to 200 parts by weight per 100 parts by weight, and 40 to 200 parts by weight.
The above object is achieved by setting the ratio of the number of fibers having a length of 600 μm to 80% or more. The method for producing a fiber-reinforced plastic rod-shaped molded article of the present invention also includes a step of molding a material containing 20 to 200 parts by weight of short glass fibers to 100 parts by weight of a thermoplastic resin to obtain a cylindrical material; A cylindrical material is rolled to form a screw thread, the short glass fibers are oriented so that 60% or more of the short glass fibers are within ±5° in the long axis direction, and the end face is threaded. The above object is achieved by exposing the fibers to the mountain side and making the ratio of the fibers having a length of 40 to 600 μm to 80% or more. Examples of the thermoplastic resin used in the present invention include polypropylene, polyethylene, polycarbonate, polystyrene, nylon, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamideimide, and polyvinyl chloride. Needless to say, there is no need to be limited to this. The glass fiber mixed with the thermoplastic resin has a diameter of 5 μm to 60 μm and a length of 1 mm to 10 mm,
The length is made to be 40 μm to 60 μm by kneading. Glass fiber is 20 to 200 parts by weight per 100 parts by weight of thermoplastic resin.
It is contained in an amount of 25 to 180 parts by weight, preferably 25 to 180 parts by weight. If it is less than 20 parts by weight, the strength of the bolt obtained will be insufficient, and the amount of exposed end face of the glass fiber on the side surface of the thread will be reduced, making the thread more likely to slip. In other words, it becomes a thread-shaped molded body that is easily loosened. If necessary, a filler, a treatment agent for improving the adhesion between the glass fiber and the resin, a flame retardant, an antioxidant, and the like may be added to the thermoplastic resin. This is kneaded using an extruder or the like and formed into a cylindrical material. The molding at this time needs to be performed so that most of the glass fibers are oriented in the longitudinal direction of the cylindrical material. For this purpose, the molding method is preferably an extrusion molding method. According to injection molding, it is generally difficult to obtain the desired orientation of the glass fibers because the flow rate of the resin in the mold is high. Furthermore, since the cross-sectional area of the resin material gate is generally wider than the cross-sectional area of the cylindrical material mold, turbulence occurs in the flow of the resin containing glass fibers near the gate, and as a result, the glass fibers are not properly oriented. To obtain the cylindrical material of the present invention by injection molding,
It is necessary to make the gate area of the injection molding machine equal to or smaller than the cross-sectional area of the cylindrical material. Needless to say, the injection direction at this time is the long axis direction of the cylindrical material. When molding, if necessary, a hexagonal head, such as a hexagonal head commonly used for bolts, may be integrally formed at one end of the molded product. In extrusion molding, a mold capable of forming this head is connected to the tip of an extruder. In injection molding, a cylindrical blank mold having an integral head shape is used. Alternatively, it is also possible to use a compression molding method in which a molded cylindrical material is cut to an appropriate length, one end of which is reheated, and a separately prepared bolt head is compressed and added. The outer diameter of the cylindrical material is determined by the size of the final bolt. For example, when obtaining a JIS M10 size bolt, a cylindrical material with a diameter of about 9 mm is prepared in advance. The rolling method adopted for threading the thread-shaped molded body of the present invention does not need to be special, and a rolling machine commonly used for thread forming of metal screws can be applied as is. An example of this is a two-roll rolling machine that rotates a pair of rolling rolls with threaded surfaces in the same direction, holds and presses a cylindrical material between them, and threads the material. round die rolling machine,
A flat die rolling machine or the like may also be used. When the cylindrical material is passed through a rolling machine, the glass fibers are broken by the threads of the rolling die, and the end faces of the glass fibers are exposed from the surface of the threads formed. The glass fibers are compressed and densely packed at the bottom of the screw. Therefore, adjacent threads are connected to each other by glass fibers at the bottom of the threads. In this way, the end faces of the glass fibers are exposed from the thread surface, and the glass fibers are densely packed at the bottom of the threads, connecting the threads that are in phase with each other, so the strength of the threads is extremely improved, and the friction The coefficient is also appropriately large, and a thread-shaped molded body that is resistant to slipping and has high fastening force can be obtained. If the orientation of the glass fibers is not sufficient, there is a risk that the glass fibers will be distributed so as to expose the sides of the formed screw thread. Furthermore, at the bottom of the screw, the glass fibers are distributed parallel to the threads, and the adjacent threads are separated from each other. Therefore, the shear strength of the threads decreases, and the friction coefficient of the thread surface also decreases, resulting in a thread-shaped molded body that is easy to slip. As mentioned above, the length of the glass fiber is 40 μm ~
Must be 600μm. Below 40μm,
The glass fibers are less likely to be broken by rolling, and the end faces of the glass fibers are less likely to be exposed from the side surfaces of the threads, making it difficult to obtain the reinforcing effect of the glass fibers as described above at the bottom of the thread. 600μm
If it exceeds this value, movement of the glass fibers during rolling becomes difficult to occur, and a thread of the desired height cannot be formed. At least 80% of the glass fibers must be in the range of 40-600 μm. (Example) The present invention will be explained below with reference to Examples. Example 1 100 parts by weight of nylon 6.6 (manufactured by Toray Industries, Inc.: Amilan resin) was mixed with 25 parts by weight of glass fibers having a diameter of 13 μm and a length of 3 mm, and the mixture was mixed with an extruder (twin-screw type kneading extruder; feed port diameter). 10mm), diameter 9mm
A cylindrical material was molded. This was rolled using a two-roll rolling machine to obtain an M10 size bolt.
Table 1(a) shows the proportion (%) of glass fibers having a length of 40 to 600 μm in the total glass fibers. An electron micrograph was taken of the cross section of the bolt obtained, and the number of glass fibers present in directions within ±5° of the axial direction was determined. Percentage of this glass fiber in the total (%)
are also shown in the table below. The following tests were conducted using this bolt to evaluate its performance. In addition, 10 bolts were used for each test, and the average value is shown. Each test was conducted in the following manner. Tensile Strength Insert M10 size nuts onto both ends of the bolt.
The maximum load just before the bolt broke was measured using an autograph. Looseness test As shown in the figure, two iron plates 1 with a thickness of 5 mm are combined and the bolts 2 and nuts 3 are tightened to a torque of 30 kg.
Tightened with cm. This is supported by a rotation support shaft 4,
500 vibrations per minute obtained through the rotating cam 5.
The degree of loosening of Nut 3 after being added for 24 hours was examined. Ease of insertion of nuts We fitted an M10 size nut onto a rolled bolt and observed how easy it was to insert the nut. In the table, ○ marks indicate a state in which the nut can be screwed in without resistance, △ marks indicate a state in which the nut is somewhat difficult to screw in, and × marks indicate a state in which it is difficult to screw in the nut even with considerable force. Example 2 Same as Example 1 except that 50 parts by weight of glass fiber was used. Example 3 Same as Example 1 except that 80 parts by weight of glass fiber was used. Example 4 Same as Example 1 except that 100 parts by weight of glass fiber was used. Example 5 Same as Example 1 except that 130 parts by weight of glass fiber was used. Example 6 Same as Example 1 except that 180 parts by weight of glass fiber was used. Example 7 The same as Example 4 except that the rotational speed of the extruder screw was reduced by about 50% and the cut length of the glass fiber was slightly increased. Example 8 As in Example 7, the number of revolutions of the extruder screw was reduced by about 50%, and the cut length of the glass fiber was slightly increased. The rest is the same as in Example 4. Example 9 The diameter of the resin supply port at the tip of the extruder was 8 mm,
It is the same as Example 4 except that the degree of orientation of the glass fibers was changed. Example 10 As in Example 9, the diameter of the resin supply port at the tip of the extruder was set to 8 mm, and the degree of orientation of the glass fibers was varied. The rest is the same as in Example 4. Comparative Example 1 Same as Example 1 except that 15 parts by weight of glass fiber was used. Comparative Example 2 Same as Example 2 except that a single screw extruder was used as the extruder. Comparative Example 3 Same as Example 2 except that the resin supply port to the mold at the tip of the extruder was 5 mm in diameter. Comparative Example 4 Same as Comparative Example 3 except that 100 parts by weight of glass fiber was used. Comparative Example 5 Same as Example 7 except that a single screw extruder was used as the extruder. Comparative Example 6 Same as Example 6 except that 210 parts by weight of glass fiber was used.

[Table] (Effects of the invention) According to the thread-shaped molded article of the present invention, ±5° in the long axis direction
Orient it so that the ratio of the number of threads existing within
In addition, the short glass fibers are contained in an amount of 20 to 200 parts by weight per 100 parts by weight of the thermoplastic resin, and the ratio of the number of short glass fibers having a length of 40 to 600 μm is said to be 80% or more, so it has high strength and high strength. It has a fastening force and is difficult to loosen. The method for producing a fiber-reinforced plastic rod-shaped molded article of the present invention also includes a step of molding a material containing 20 to 200 parts by weight of short glass fibers to 100 parts by weight of a thermoplastic resin to obtain a cylindrical material; A thread is formed by rolling a cylindrical material, and the short glass fibers are oriented so that 60% or more of the short glass fibers are within ±5° in the long axis direction, and the end face is threaded. Since the ratio of the number of fibers exposed on the mountain side and having a length of 40 to 600 μm is said to be 80% or more, a cylindrical plastic material reinforced with glass fibers can be obtained, which can be rolled. Thread processing is highly productive, so the threads of the resulting plastic screw-shaped molded product do not become double-threaded, cracked, or split, and have high strength, high fastening force, and are resistant to loosening. Moreover, a thread-shaped molded body that is lightweight and highly corrosion resistant can be easily obtained.

[Brief explanation of drawings]

The figure is a side view of essential parts showing an example of an apparatus for testing the loosening of a thread-shaped molded body according to the present invention. 1... Iron plate, 2... Bolt, 3... Natsu, 5
...rotating cam.

Claims (1)

[Claims] 1. The ratio of the number of fibers existing within ±5° in the major axis direction is
It is composed of a thermoplastic resin containing short glass fibers that are oriented so as to occupy 60% or more and whose end faces are exposed on the side surface of the screw thread, and the short glass fibers are oriented in a proportion of 20 to 200 parts by weight per 100 parts by weight of the thermoplastic resin. Contains a portion of
A fiber-reinforced plastic thread-shaped molded article in which the ratio of the number of fibers having a length of 40 to 600 μm is 80% or more. 2. A step of forming a material containing 20 to 200 parts by weight of short glass fibers per 100 parts by weight of a thermoplastic resin to obtain a cylindrical material, and rolling the cylindrical material to form a thread, The short glass fibers are oriented so that 60% or more of the fibers are within ±5° in the major axis direction, the end faces of which are exposed to the side surface of the thread, and the length of the fibers is 40 to 600 μm. A method for producing a fiber-reinforced plastic screw-shaped molded article, characterized in that the ratio of the above is 80% or more.