JPH0891271A - Coupling method of joint and pipe in bicycle - Google Patents

Abstract

PURPOSE: To provide a concrete method of a double structure to form a circular clearance at the pipe side end in order to reinforce the connection of a joint and a pipe in a bicycle, to form a thick wall by making the connection in a triple structure when the circular projection of the pipe is inserted to the circular clearance, and furthermore, to increase the contact area when they are fixed through an adhesive and the like, so as to improve the combining strength. CONSTITUTION: A method to combine a joint and a pipe solidly is provided, when a joint 4 and a pipe 6 of a bicycle are combined, by providing a process to form a reinforcing member 8 in which a small diameter part 8a at the front end side, and a large diameter part 8c at the base side are provided; a precess to insert the large diameter part side of the reinforcing member 8 to the inside of the pipe 6 so as to combine and fix the large diameter part 8a and the inner surface of the pipe 6, and to form a circular clearance between the small diameter part 8c and the pipe front end part 6c; and a process to insert the circular projection 4b of the joint 4 in the circular clearance so as to fix integrally at the whole contact surfaces of both members.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting a joint and a pipe in a bicycle, and more particularly to a joint and a pipe which are strengthened through a reinforcing member. The present invention relates to a method for connecting a joint and a pipe, which is effective for a lightweight bicycle.

[0002]

2. Description of the Related Art FIGS. 5 and 6 show an example of a joint structure of a joint and a pipe in a conventional bicycle. Fifth
The drawing shows a case where a hawk crown is used as the joint 4 and a hawk stem is used as the pipe 6 (Shokai 62-189295). Since the front fork is directly connected to the handle, strong stress concentration is likely to act thereon, and it is desirable to form the front fork as thick as possible. In this figure, the pipe tip portion 6b is reduced in diameter via a tapered portion 6a, and the pipe tip portion 6b is screwed into an annular protrusion portion 4b for joining the joint 4 to form an annular protrusion portion. The thickness of 4b is aimed at.

FIG. 6 shows a case where a head lug is used as the joint 4 and an upper pipe is used as the pipe 6 (actually developed 62-16090).
No.). In this case, in order to strengthen the joint portion where stress concentration is likely to occur, the annular protrusion 4b of the joint 4 is formed in a double structure of an outer annular protrusion and an inner annular protrusion,
The distal end 6a of the pipe 6 is inserted into the annular gap between the two annular projections, and the contact portion between the pipe 6 and the annular projection 4b is fixed with an adhesive.

[0004]

In the conventional connecting structure shown in FIG. 5 showing the front fork portion, the connecting portion has an annular protruding portion 4.
The thickness of the joint is not sufficient because of the double structure of the pipe b and the pipe tip 6b. In the case of a lightweight bicycle made of aluminum or the like for the joint 4, the strength of the joint with respect to stress concentration is still insufficient. I couldn't say it, but I couldn't dispel my strong sense of anxiety.

Further, in the conventional connecting structure shown in FIG. 6 showing a head lug, the annular protruding portion 4b of the joint 4 has a double structure, so that the pipe end portion is fitted and connected to this double portion. It seems to be sufficient in strength because it can increase the wall thickness of the part and the adhesion area by the adhesive, but in fact, it contains a fundamental defect. Shokai 6 discloses this technology
Japanese Patent Application Laid-Open No. 2-16090 does not describe at all how to form a double annular projection on the joint 4. Therefore, although there is a point of interest called a double annular projection, the coupling structure is not practical. Generally, as a method of forming a bicycle joint, there are a case of forming from one sheet metal and a case of bulge forming from a pipe, but in either case, a double annular protrusion as described in the drawings of the above publications. Is impossible to form. Furthermore, in the case of molding by casting, since the double annular protrusion is joined only at the root, the joint is weak in strength and cannot be realized. If the joint portion is lengthened in the axial direction in order to improve this weak point, the following drawbacks occur. That is, since the annular projection on the joint side cannot be projected so large in size, the double portion is shortened and the contact area with the pipe is reduced, so that the initial purpose cannot be achieved.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned drawbacks. Briefly, the main part of the present invention is to provide a small-diameter portion at the distal end side when connecting a joint and a pipe in a bicycle. Forming a reinforcing member having a reduced diameter and a large diameter portion provided on the base end side in an enlarged diameter shape, and inserting the large diameter portion side of the reinforcing member into the inside of the pipe to form a large diameter portion. And a pipe inner surface are connected and fixed, and an annular gap is formed between the small-diameter portion and the pipe tip. An annular projection of the joint is fitted into the annular gap to form the annular projection and the small-diameter portion. And a third step of fixing the tip of the pipe to each other.

[0006]

Unlike the Japanese Utility Model Laid-Open No. 62-16090, it is important for the inventors to form the double annular protrusion on the end of the pipe rather than on the joint side, and to reinforce the double annular protrusion. We have come to know the method to realize by using members. First, a reinforcing member consisting of a large-diameter portion and a small-diameter portion is formed, and the reinforcing member is inserted into the pipe from the large-diameter portion side and the large-diameter portion is fixedly connected to the inner surface of the pipe. Will be placed on the side. That is, in terms of the double annular protrusion, the small diameter portion is formed in the inner annular protrusion, and the pipe tip is formed in the annular gap corresponding to the outer annular protrusion, and the double annular protrusion is formed in the pipe. It can be realized at the end. Next, the fitting and the pipe can be strongly connected by fitting the annular protruding portion on the joint side into the annular gap and fixing it with an adhesive or the like.

Since the reinforcing member is inserted into the pipe, the axial length of the large diameter portion can be made as long as desired, and the contact area between the pipe and the reinforcing member can be increased to strengthen the bonding strength between them. Similarly, the axial length of the small-diameter portion can be increased, so that the axial length of the annular gap portion increases, so that the contact area with the annular protrusion of the joint can be increased and the joint can be made thicker.
When connecting the pipe and the reinforcing member, both members can be fixed at a large diameter portion by welding or brazing in the case of steel, and can be fixed by an adhesive in the case of carbon or aluminum. Further, when joining the annular protruding portion of the joint and the annular void portion, depending on the material, for example, in the case of steel or the like, welding such as brazing can be performed, but a lightweight material such as an aluminum material or a carbon material is used. In this case, an adhesive can be used, and the present invention can be particularly effective in a lightweight bicycle.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view of a main part of the front fork 2, and FIG. 2 is an exploded view of the same. In the figure, 4 is a joint showing a hawk crown, and a pair of joint portions 4a, 4a and an annular projecting portion 4b which are coupled to a front hawk leg (not shown) are formed, and a base portion thereof is provided with an enlarged diameter portion 4f. A hollow portion 4c is bored inside the annular protruding portion 4b, and a concave portion 4d is provided at the lowermost end thereof via a step portion 4e. 5
Is a screw, which is composed of a head portion 5a and a screw portion 5b. Reference numeral 6 denotes a pipe 6 representing a fork stem, and an end 6d of a pipe tip 6c is enlarged in diameter so as to fit into the enlarged diameter portion 4f. Reference numeral 8 denotes a reinforcing member having a large-diameter portion 8a having an outer diameter substantially equal to the inner diameter of the pipe 6 formed at a base end thereof, and a small-diameter portion 8c formed at a distal end from the large-diameter portion 8a via an intermediate portion 8b. I have. The inner surface of the small diameter portion 8c is formed on a screw surface 8d. The intermediate portion 8b may be a tapered taper portion or a vertical step portion. As a method of forming the reinforcing member 8, a method generally used in the field of bicycles, for example, bulging as an internal pressure processing method is used.

In this embodiment, the joint 4 is made of aluminum in order to reduce the weight, but the pipe 6 and the reinforcing member 8 are made of steel in terms of strength. Therefore,
The large diameter portion 8a of the reinforcing member 8 and the inner surface of the pipe 6 are fixed by brazing or welding. In this connection, the large-diameter portion 8a is formed in a cylindrical shape, and its outer shape is substantially equal to the inner diameter of the pipe 6, so that the reinforcing member 8 can be smoothly inserted into the pipe 6, and is regulated by the large-diameter portion 8a. Therefore, centering of the reinforcing member 8 with respect to the pipe 6 can be automatically performed without unevenness. When the pipe 6 is a lightweight material such as a carbon material, the large-diameter portion 8a may be fixed by an adhesive, and in that case, the axial length of the large-diameter portion 8a can be increased to increase the adhesion area. When connecting the reinforcing member 8 to the pipe tip, the small diameter portion 8c needs to be positioned on the opening side of the pipe 6. In addition, as a result of this coupling, between the small-diameter portion 8c and the pipe tip 6c, an annular space 6e substantially equal to the thickness of the above-mentioned annular protrusion 4b is formed.
Is formed.

Next, the procedure for assembling these members will be described. An adhesive is applied to the inner surface of the pipe tip portion 6c forming the annular space 6e and the outer surface of the reinforcing member 8, and the inner and outer surfaces of the annular protruding portion 4b. Also, an adhesive is applied, and then the annular protruding portion 4b is fitted into the annular void portion 6e so that the end portion 6d is completely fitted onto the expanded diameter portion 4f. Next, screw 5 into recess 4
d and screwed into the screw surface 8d until the head 5a comes into contact with the step 4e. As a result, the assembled state of FIG. 1 is completed.

According to this embodiment, the annular protruding portion 4b is sandwiched between the reinforcing member 8 and the pipe tip portion 6c from the inner and outer surfaces, and as a result, the adhesion area is increased and the triple structure can be made thicker so that stress concentration can be achieved. It is possible to improve the safety by strengthening the joints where Also, since the pipe 6 as a fork stem is externally fitted to the annular projection 4b, the pipe 6
The outer surface of the end 6d is not contaminated. Therefore, if the end portion 6d is accurately formed, the outer surface processing after the bonding is unnecessary, and the number of steps can be reduced as compared with the conventional case. That is, as shown in FIG. 1, the ball receiver A can be arranged without post-processing.

Next, another embodiment will be described with reference to FIGS. 3 and 4, and the same portions are denoted by the same reference numerals and description thereof will be omitted. Reference numeral 4 denotes a joint showing a head lug, but the same applies to a hanger lug, a seat lug, a back bridge, a front end, and a rear end. Similarly, 6 is an upper pipe, but a lower pipe, a vertical pipe,
The same is true for back hawks, chain stays, and front hawk legs. At the base of the annular projection 4b of the joint 4 is a base 4g.
Are formed in an enlarged diameter shape. Further, the inner surface of the small diameter portion 8c is not provided with a screw surface and is smooth. In order to change FIG. 3, which is an exploded view, to FIG. 4, which is a sectional view of an essential part after completion of assembly, the annular protrusion 4b coated with the adhesive is replaced with the annular void 6e coated with the adhesive. Just fit in. Since the effect is almost the same as that of the first embodiment, the description is omitted.

The present invention can also be used for connecting pipes to joints such as hanger lugs, seat lugs, back bridges, front ends, rear ends, etc. In that respect, the present invention is not limited to the above embodiments, and the present invention The present invention includes various modifications, design changes, etc. within the technical scope of the invention.

[0014]

As described in detail above, the present invention forms a reinforcing member having a large-diameter portion and a small-diameter portion, and inserts and fixes the large-diameter portion in a pipe to fix the small-diameter portion of the reinforcing member and the tip of the pipe. And an annular gap is formed between them. Therefore, a concrete method for realizing the double structure is established. next,
Since the annular projection of the joint is fitted and fixed in the annular gap, the joint can be triple-thickened, and at the same time, the large diameter portion and the small diameter portion have variable axial lengths for bonding. The area can be increased, and the coupling strength can be remarkably improved.

[0015]

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts showing a first embodiment of the present invention.

FIG. 2 is an exploded view of the first embodiment.

FIG. 3 is an assembly exploded view showing a second embodiment.

FIG. 4 is a cross-sectional view of essential parts of a second embodiment.

FIG. 5 is a cross-sectional view of a main part showing a conventional example.

FIG. 6 is a sectional view of an essential part showing another conventional example.

[Explanation of symbols]

 Reference Signs List 4 Joint 4b Annular protrusion 6 Pipe 6c Pipe tip 6e Annular gap 8 Reinforcement member 8a Large diameter portion 8c Small diameter portion

Claims (3)

[Claims] 1. When connecting a joint 4 and a pipe 6 in a bicycle, a reinforcing member 8 is formed in which a small diameter portion 8c is provided in a reduced diameter shape at a tip end side and a large diameter portion 8a is provided in an enlarged diameter shape at a base end side. In the first step, the large-diameter portion side of the reinforcing member 8 is inserted into the pipe 6 to bond and fix the large-diameter portion 8a and the inner surface of the pipe, and the annular portion is provided between the small-diameter portion 8c and the pipe tip portion 6c. Second step of forming the void 6e and the annular void 6e
The annular protrusion 4b of the joint 4 is fitted into the annular protrusion 4b.
And a third step of fixing the small diameter portion 8c and the pipe tip 6c to each other. 2. The coupling method according to claim 1, wherein the joint 4 is a hawk crown, a head lug, a hanger lug, a seat lug, a back bridge, a front end and a rear end. 3. The method according to claim 1, wherein the pipe is a fork stem, an upper pipe, a lower pipe, a standing pipe, a back fork, a chain stay, and a front fork leg.