JPH02220989A - Jointing method of bicycle lug and frame pipe - Google Patents

Abstract

PURPOSE:To simplify a mechanical process and shorten the length of a bulged projection by drilling to provide a through-hole in the center of a bulged projection end surface immediately after forming the bulged projection end surface on a pipe wall of a metal pipe with the bulging technique, and using a cylindrical material formed with a projection to be engaged with that through-hole as an inner tube to joint frame pipes. CONSTITUTION:Through-holes 3, 5 having the size of about one tenth of the end surface area are drilled to be provided around of the centers of the bulged projection end surfaces of a head lug 1 formed by the bulging technique. The complicated processes such as cutting opening, fairing and inner diameter processing, etc., are thereby eliminated. Inner tubes 6 comprising a projection to be inserted into through-holes 3, 5 of the bulged end surfaces are prepared, and the projection 7 is inserted into through-holes 3, 5, and contact surfaces to be adhered of the bulged end surface with a through-hole and the inner tube end surface with a projection are jointed by an appropriated jointing method such as welding, wax joint and adhesive joint, etc. A frame pipe 11 is then engaged with the inner tube 6 provided in the head lug 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of joining a lug, such as a head lug, which is a joint part of a bicycle, and a frame pipe that constitutes a bicycle body.

The bicycle frame and pipes are inserted into the holes of the appropriate lug parts and joined using an appropriate adhesive method such as welding, brazing, or adhesive bonding, but several steps are required before doing so. .

(Prior art) Regarding the head lug made as a lug member by the hydraulic bulge molding method, the product just removed from the mold is as shown in Figure 1 of the attached drawings, and two pieces are placed on the side wall of a metal tube. It has bulging protrusions 2 and 4. The end of this bulging protruding wall is cut to make an opening, and the cut opening surface is shaped.
Finally, the bulging protrusion becomes a lug member only after internal diameter machining.

Although it is shown that through holes 3 and 5 are bored in the center of the end faces of the bulging projections 2 and 4 shown in FIG. 1, these through holes 3 and 5 will be described later. .

Furthermore, in order to maintain the strength of the lug, the lug portion needs to have a certain length. This length will be explained with reference to the sectional view of FIG. Figure 2 shows head lug 1
One of the protrusions 2 is cut along the tube axis χ, and the angle formed at the intersection of the tube axis χ and a vertical line passing through the center of the end face is indicated by θ.

The length of the vertical line is the length above. Needless to say, as this length increases, the area of contact between the lug member and the frame pipe increases, and therefore the strength of the connection also increases.

Current bulge forming technology limits the length h of the bicycle head lug to 27 to 45 m.

(Problems to be Solved by the Invention) The head lugs of bulge forming have the above-mentioned problems, namely, the first is the mechanical processing performed immediately after the above-mentioned bulge forming, and the second is the bulge forming. This is a constraint on the length of the bulging protrusion obtained by.

(Means for Solving the Problems) The present invention has succeeded in solving the above two problems at once.

The above-mentioned processing after the first bulge forming is discontinued, and only one step of drilling a through hole in the center of the end face of the bulging protrusion is added, and the closed end face is provided with a protrusion that can be inserted into this through hole. The cylindrical body is used as an inner tube.

The first problem has been solved by shortening the aforementioned process to one step, and the second problem has also been solved by adopting the inner tube of the present invention.

The attached drawings will be explained below.

FIG. 1 is a sketch of a head lug 1 molded by the bulge molding method, as it is taken out from the mold, and has bulging protrusions 2 and 4. However, the through holes 3 and 5 will be described later. Conventionally, it has been necessary to perform the above-mentioned processing on the ends of these bulging protrusions.

According to the present invention, as shown in FIG. 1, through holes 3 and 5 having a size approximately one-tenth of the area of the end surface are bored around the center point on the end surface of the bulging protrusion. - For example, the diameter of the end face is usually 28 to 32 cm, and the area of a circle with a diameter of 8 m is about 1/10 or less of the area of a circle with a diameter of 28III11.

However, it is not limited to this.

According to the present invention, processing of the end face of the bulging protrusion involves simply drilling a through hole with a size of about 1/10 of the circular area of the end face. Complicated processes such as shaping and inner diameter machining are no longer necessary.

Next, an inner tube 6 equipped with a protrusion 7 to be inserted into the through hole 3 or 5 passing through the center of the end face is prepared.The appearance of this inner tube 6 is as shown in FIG. The figure is a cross section of FIG. 3, and FIG. 5 is a view from the open end of the inner tube 6.

Reference numeral 8 shown in FIGS. 3 to 5 is a costal rib, the use of which will be described later.

An example of the size of this inner tube 6 is:
The length is approximately 40 mm, and this length is preferably approximately twice the inner diameter 22 to 23 of the frame pipe.The wall thickness of the inner tube 6 is not particularly specified, but 2 m is sufficient. The outer diameter of the inner tube should be large enough to fit the frame pipe.

The reason why the open end of the inner tube 6 is bent inward is that when fitting the frame pipe,
I simply adopted the usual method to make it easier to fit.

Fig. 6 shows a state in which the protrusion 7 installed on the inner tube 6 is inserted into the through hole 3 of the bulging end face, and Fig. 7 shows the completion of insertion. Since the diameter is smaller than the diameter of the protruding end surface, the bulging end surface with the through hole and the end surface of the inner tube with the protrusion are in close contact with each other, and the mutual contact surfaces are welded or brazed. Join by an appropriate joining method such as bonding or adhesive joining.

FIG. 8 shows a completed view of the present invention, in which the inner tube 6 is installed on the head lug 2 and the frame pipe 11 is fitted into the inner tube 6 to complete the process.

Next, we will discuss how to join each part.

Recently, the ability to reduce the weight of bicycles has been called out, and each part, frame,
A variety of pipes made from new materials are emerging.

Therefore, at present, a wide variety of bonding methods such as welding, brazing, and the use of synthetic resin bonding agents are employed depending on the type of material that constitutes each part.

The above-mentioned inner tube with ribs 8 is intended for use with a synthetic resin adhesive.

As mentioned above, the present invention is a useful invention that makes full use of the lug member formed by bulge forming by directly drilling the bulge end face of bulge forming and fixing an inner tube with a matching protrusion. It is what it is.

[Brief explanation of the drawing]

Figure 1 shows what is drilled in the center of the end face of the head lug after bulge forming, Figure 2 is a sectional view of the lug member, Figure 3 is a sketch of the inner tube, Figure 4 is its cross section, and Figure 5. Figure 6 shows the lug member inserted into the inner tube, Figure 7 shows the completed assembly of the lug member and inner tube, and Figure 8 shows the frame pipe inserted into the inner tube. This is a diagram of the completed fitting. l: head lug, 2: bulging protrusion, 3: hole on end face, 4: bulging protrusion, 5: hole on end face, 7: protrusion, 9: curved part, 6: inner tube, 8: lip, lO: Part equivalent to frame pipe wall thickness, 11: Frame pipe.

Claims (1)

[Claims] A through hole of a predetermined size is formed in the center of a metal tube wall immediately after forming a plurality of bulging protrusion end surfaces by bulge forming technology, and the closed end surface of a cylindrical body has a closed end surface at one end that is slightly smaller than the end surface. A protrusion is formed in the center of the cylindrical body to fit the through hole formed in the center of the end face of the bulge.
A method of joining a bicycle lug component comprising a tube and a frame pipe via the inner tube.