JPH06144334A - Preparation of bicycle frame - Google Patents

Abstract

PURPOSE: To provide a method for assuredly manufacturing a non-ferrous metal frame of a bicycle at low cost. CONSTITUTION: A method for manufacturing a frame of a bicycle by connecting a plurality of tubes together by means of a joint having connecting tube parts comprises the steps of providing grooves 2c on the inner walls of the connecting tube parts 2b of the joint whose inside diameter is substantially equal to the outside diameter of the tubes 1, inserting the ends of the tubes 1 into the connecting tube parts 2b and applying pressure to the inner walls of the tubes 1 to connect the tubes 1 in tight contact to the grooves 2c in the connecting tube parts 2b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bicycle frame manufacturing method.

[0002]

Bicycles are widely used as a healthy and convenient vehicle. Until now, iron has been used as a material for bicycle frames, but it is difficult to reduce weight while maintaining strength, so products that use non-ferrous metals such as aluminum, aluminum alloys, and titanium alloys instead of iron. Is increasing. As in the past, if the material of the tubes that make up the bicycle frame is iron, they can be joined by welding, but in the case of non-ferrous metals as described above, joining by welding can be achieved only under extremely limited conditions. First of all, enormous capital investment is required to stably produce high-quality products. Therefore, a method of screwing the inside of the connecting pipe part and the outside of the tube to screw and join, or a joining method by an adhesive was devised, but in the former, the member becomes thin by cutting the screw, so the strength decreases, Further, there is a problem in that the work of cutting and connecting the plurality of tubes with screws on both sides is time-consuming and thus inefficient in production. On the other hand, in the latter, the work itself is easy, but if the gap between the connecting pipe part and the tube is too large or conversely too small, the bonding force will weaken, and after some time, the adhesive itself will There is a problem that it may deteriorate and the joint may loosen.

Therefore, a method of utilizing elasticity has been developed in order to realize a stronger bond. This is to provide a step at the end of the tube to be inserted into the connecting pipe, the outer diameter of which is larger than the inner diameter of the tip of the connecting pipe. This is a method in which a step portion corresponding to the step portion provided on the tube is largely provided, and the tube is pushed into the connecting pipe portion and fitted therein. However, this method has a problem that if the molding of the step portion provided in the connecting pipe portion and the tube is not precise, there is a problem in the strength, and it takes a cost to perform the precise molding.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a method for reliably manufacturing a bicycle frame made of non-ferrous metal at low cost. To do.

[0005]

The above object is to provide a groove in the inner wall of the connecting pipe portion and to insert the end portion of the tube into the connecting pipe portion in the manufacture of a bicycle frame composed of the tube and the joint. And a step of applying pressure to the inner wall of the tube to bring the tube into close contact with the groove in the connecting pipe portion and then joining the tubes.

[0006]

According to the method as described above, it is possible to inexpensively mass-produce the frame of the non-ferrous metal bicycle.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the configuration of the present invention will be specifically described with reference to the drawings. 1 is a perspective view showing a bicycle frame assembling state, FIG. 2 is a partial cross-sectional view showing a joining portion by a known joining method using an adhesive, and FIG. 3 is a portion showing a joining portion by a known joining method using elasticity. Sectional drawing, FIG. 4 is a partial sectional view showing the construction of an embodiment joined by the joining method according to the present invention, and FIG. 5 is a partial sectional view showing the construction of another embodiment of the present invention. In the figure, 1 is a tube, 2 is a joint, and 3 is a reinforcing tube.

As shown in FIG. 1, the bicycle frame 10 comprises a plurality of tubes 1 having different lengths joined by a plurality of joints 2 having different shapes. The joint 2 is composed of a main body portion 2a and a connecting pipe portion 2b having an inner diameter substantially equal to the outer diameter of the tube 1, and the end portions of the tube 1 are inserted into the corresponding connecting pipe portions 2b of the joint 2, respectively, Fixed in the way. What is shown in FIG. 2 is a connecting pipe portion 2b.
This is a known embodiment in which the adhesive 4 is interposed in the gap provided between the outer wall of the tube 1 and the inner wall of the connecting pipe portion 2b inserted into the tube, and the two are joined together. In FIG. 3, a step portion whose outer diameter is larger than the inner diameter of the tip of the connecting pipe portion 2b is provided at the end portion of the tube 1, and a step portion corresponding to the step portion of the tube 1 is provided at the back of the connecting pipe portion 2b. Provide the tube 1 in the connecting tube 2b
Another known embodiment of pushing in and mating is shown. Next, the present invention will be described with reference to FIG. First, a plurality of annular grooves 2c that surround the inner wall of the connection pipe portion 2b of the joint 2 including the main body portion 2a and the connection pipe portion 2b are provided. Then, after inserting the end portion of the tube 1 into the connecting pipe portion 2b, pressure is applied to the inner wall of the tube 1 until the tube 1 comes into close contact with the groove 2c in the connecting pipe portion 2b.
And joint 2 are joined. Further, as shown in FIG. 5, a reinforcing tube 3 having an outer diameter substantially equal to the inner diameter of the tube 1 is inserted into the tube 1, and the reinforcing tube 3 is deformed.
It is recommended that the strength be increased by performing similar processing until it comes into close contact with.

In the method of joining the bicycle frame 10 according to the present invention constructed as described above, the end of the tube is inserted into the pre-processed connecting pipe portion 2b and the tube 1 is processed from the inside. Since the tube 1 can be reliably joined to the connecting pipe portion 2b, the bicycle frame 10 can be easily assembled. For this processing, processing methods such as drawing, hydrostatic processing, explosion molding, and underwater discharge are used. Further, the structure of the present invention is not limited to the above-mentioned embodiment, and the shapes of the groove and the other parts provided in advance in the connection part can be freely modified within the scope of the object of the present invention. .

[0010]

Since the present invention is constructed as described above, according to the present invention, a bicycle frame made of non-ferrous metal can be reliably manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a perspective view showing a bicycle frame assembly state.

FIG. 2 is a partial cross-sectional view showing a joined portion by a joining method using a known adhesive.

FIG. 3 is a partial cross-sectional view showing a joined portion by a known joining method using elasticity.

FIG. 4 is a partial cross-sectional view showing an embodiment joined by the joining method according to the present invention.

FIG. 5 is a partial cross-sectional view showing another embodiment of the present invention.

[Explanation of symbols]

 1 ... Tube 2 ... Joint 2a ... Main body 2b ... Connection tube 2c ...・ ・ ・ Groove 3 ・ ・ ・ ・ ・ ・ ・ ・ Reinforcement tube 4 ・ ・ ・ ・ ・ ・ Adhesive 10 ・ ・ ・ ・ ・ ・ Bicycle frame

Claims (4)

[Claims] 1. A bicycle frame (10) according to a method for manufacturing a bicycle frame (10) by connecting a plurality of tubes by a joint having a connecting pipe portion, comprising the following steps. Manufacturing method. A) Connection pipe part (2b) of joint (2) having connection pipe part (2b) whose inner diameter is substantially equal to the outer diameter of tube (1)
Of forming the groove (2c) on the inner wall of the. (B) A step of inserting the end portion of the tube (1) into the connecting pipe portion (2b). C) Pressure is applied to the inner wall of the tube (1) to bring the tube (1) into close contact with the groove (2c) in the connecting pipe part (2b),
The process of joining. 2. The method for manufacturing a bicycle frame according to claim 1, wherein the groove (2c) provided in the inner wall of the connecting pipe portion (2b) is an annular groove that surrounds the inner wall. 3. A bicycle frame (10) according to a method for manufacturing a bicycle frame (10) by connecting a plurality of tubes by means of a joint having a connecting pipe portion, comprising the following steps. Manufacturing method. A) Connection pipe part (2b) of joint (2) having connection pipe part (2b) whose inner diameter is substantially equal to the outer diameter of tube (1)
Of forming the groove (2c) on the inner wall of the. (B) A step of inserting the end portion of the tube (1) into the connecting pipe portion (2b). C) Pressure is applied to the inner wall of the tube (1) to bring the tube (1) into close contact with the groove (2c) in the connecting pipe part (2b),
The process of joining. D) A step of inserting the reinforcing pipe (3) whose outer diameter is substantially equal to the inner diameter of the tube (1) into the tube (1). E) A step of applying pressure to the inner wall of the reinforcing pipe (3) to bring the reinforcing pipe (3) into close contact with the deformed tube (1). 4. The method of manufacturing a bicycle frame according to claim 3, wherein the groove (2c) provided on the inner wall of the connecting pipe portion (2b) is an annular groove that surrounds the inner wall.