JPS6249174B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a bolt from a fiber-reinforced thermoplastic synthetic resin by a rolling method.

Conventionally, one method of manufacturing bolts made of synthetic resin is to manufacture bolts by forming threads using a rolling method on a cylindrical material molded from thermoplastic resin in which reinforcing fibers are dispersed. is being carried out. In this manufacturing method, the threads are formed by cold working, and bolts can be manufactured easily and in large quantities, so it is suitable for mass production of bolts, but the resulting bolts are as follows: It has drawbacks. In other words, there is a problem with the accuracy of thread machining,
In particular, the shape of the tip of the screw thread is rounded or there is a dent in the center of the top of the thread, making it difficult to obtain a product with good precision.Furthermore, when the product obtained is used, the temperature of the atmosphere rises. Then,
There is a drawback that the thread shape is restored and deformed in the direction of returning to the original shape before processing, and therefore the operating temperature must be limited to a relatively low temperature or lower.

The present invention is suitable for mass production, but in view of the current state of rolling methods in which the products manufactured thereby have the drawbacks mentioned above, an object of the present invention is to provide a manufacturing method that eliminates the above drawbacks. The gist of this method is to roll a cylindrical material made of a thermoplastic resin containing dispersed reinforcing short fibers and reinforced with a large number of long fibers whose centers are aligned in the longitudinal direction. A method for manufacturing a composite bolt, characterized in that when manufacturing a bolt by threading, the soybean on a rolling machine is preheated to a temperature of 50°C or higher and lower than the melting point of the thermoplastic resin. exists in

In the present invention, fibers are used for reinforcement, and examples of this fiber material include glass, carbon,
There are inorganic fibers made from silicon carbide, alumina, etc., and organic fibers such as aramid fibers, and it is also possible to use a mixture of two or more types of fibers, as well as long fibers and thermoplastic resins that reinforce the center. The short fibers dispersed in the fibers may be of the same type or of different types. Regarding the length of the fibers, in order to have sufficient strength in the longitudinal direction, the fibers must be long fibers aligned in the longitudinal direction, but they are dispersed in the thermoplastic resin. As for the short fibers, it is preferable to use fibers cut into lengths of 1 mm to several centimeters to ensure good dispersion.

Further, the thermoplastic resin used in the present invention includes polyamide, polycarbonate, polyacetal, polypropylene, polyethylene, polyethylene terephthalate, polyvinyl chloride, etc., and the type thereof is not particularly limited. Further, various additives such as fillers, processing agents for improving adhesion to fibers, flame retardants, and antioxidants may be mixed into the resin as necessary.

Next, various methods can be used to prepare the cylindrical material, but in order to manufacture it continuously and efficiently in a simple process, it is best to use an extrusion method, such as a cross-head die. A mixture of thermoplastic resin and short fibers is supplied to the extruder while passing the continuous long fibers through the die and continuously taking them out from the outlet of the die, and in the die, the long fibers are A preferred method is to prepare a cylindrical material by extruding it from the die outlet with the thermoplastic resin composition surrounding and integrating the material, sizing and cooling it appropriately, and cutting it to an appropriate length. I can do it.

Therefore, in the present invention, bolt threading is performed by a rolling method, and both a round soybean rolling machine and a flat soybean rolling machine can be used as the device for performing the rolling. . During this rolling process, the soybeans on the rolling machine are preheated to a temperature of 50°C or higher and lower than the melting point of the thermoplastic resin used, and the heated soybeans form threads on the bolt material to form threads. This is a feature of the present invention.

In order to heat the soybeans on the rolling machine, any conventionally known heating method can be used, and for example, heating means such as heating oil or electric heaters are recommended.

As mentioned above, by performing rolling using rolling machine soybeans heated to a specific temperature range, unlike bolts manufactured by conventional methods, when the temperature during use becomes relatively high for some reason, This eliminates the disadvantages of deformation of the threaded portion, and at the same time allows thread processing to be carried out with high precision, resulting in the production of bolts that meet specifications. Furthermore, according to the method of the present invention, a product with improved strength as a bolt can be obtained compared to the conventional rolling method, and this product is reinforced with long fibers whose centers are aligned in the longitudinal direction. In addition, the tendency of reinforcing fibers to easily break due to the pressure during rolling in conventional rolling at room temperature has been changed by using heated rolling soybeans, making it difficult for reinforcing fibers to break. This is thought to be because the reinforcing effect of the fibers is more fully exhibited. The method for manufacturing the composite bolt of the present invention is as described above, in particular, the soybeans on the rolling machine are preheated to a specific temperature and threaded, and the center is reinforced with long fibers aligned in the longitudinal direction. Since this method uses the bolt material that has been
This makes it possible to manufacture fiber-reinforced thermoplastic resin bolts with high dimensional accuracy, which prevents thermal deformation and improves strength.

The present invention will be explained below based on Examples.

Example 1 An extruder with a crosshead die was used, and the die was configured to continuously feed long glass fibers to the center, while the extruder hopper was supplied with glass fibers in the form of a chop strand having a length of 3 mm. Thermoplastic polyester resin mixed with 20% by weight is supplied, the extruder is operated, and the glass long fibers and short fiber-mixed polyester resin are surrounded by the resin around the long fibers in the crosshead die. A bolt material having a diameter of 9 mm was prepared by extruding the extruded rod into a cylindrical rod, taking it through a cooling sizing device, and cutting it into regular lengths.

In addition, 17 glass rovings of 2.4 g/m were used as the long glass fibers, and the total amount of glass in the obtained bolt material was 50% by weight (long fiber content
37.5% by weight, short fiber content 12.5% by weight).

Next, as a rolling device, a round soybean rolling machine equipped with a roller die having an outer diameter of 140 mm, a width of 60 mm, and a thread groove of 1.5 mm is used, and the roller die is brought into contact with heated silicone oil.
The bolt material was heated to .degree. C., and the bolt material was supplied to the heated roller soybean and subjected to thread processing to produce a bolt. In this manufacturing process, the time required to thread one bolt was approximately 3 seconds.

The bolt thus obtained has an outer diameter of approximately 10 mm and a root diameter of 8.
mm, pitch 1.5mm, the thread had a sufficient bulge, and fit well with a ready-made 10mm nut.

Attach metal bolts to both ends of the bolt,
As a result of a tensile test according to JISB1051, the maximum tensile load was 950 kg. Also, this bolt is 100
When heated to ℃, there was almost no dimensional change and the dimensional stability was excellent.

Comparative Example A bolt material was prepared in the same manner as in Example 1, except that a rod with a diameter of 9 mm extruded from thermoplastic polyester resin without glass fibers was used as the bolt material, and a bolt was made in the same manner as in Example 1. Manufactured. The maximum tensile load of this bolt is
It weighed 350Kg.

Claims (1)

[Claims] 1 Bolts are manufactured by threading a cylindrical material made of a thermoplastic resin containing dispersed reinforcing short fibers and reinforced with a large number of long fibers whose centers are aligned in the longitudinal direction using a rolling method. In doing so,
A method for manufacturing a composite bolt, which comprises preheating soybeans on a rolling machine to a temperature of 50° C. or higher, lower than the melting point of the thermoplastic resin, and threading the soybeans.