JPS5947017A - Manufacture of metallic pipe - Google Patents

Abstract

PURPOSE:To obtain a lightweight metallic pipe having the prescribed length and thin wall thickness, by forming one end of a short-sized metallic pipe into a radially expanded part having thick wall thickness, and stretch forming the total length of the pipe by drawing the remaining part of it. CONSTITUTION:The 1st drawing is performed by pressing a metallic pipe 7 of short-sized blank material into the 1st die hole 5 having the 1st radially expanding part at its upper opening, by a punch 8 in a cold state. Successively, a perfect radially-expanded part is formed at the upper end of the metallic pipe 7 in the 2nd drawing state. Next, the pipe is pressed into the 3rd die hole 14 of the 3rd die 15 in a cold state. The 3rd punch 16 is inserted through the inner hole of the pipe to press its inner peripheral surface, thereby the inner peripheral surface of the pipe 7C is radially expanded to form the pipe into the thin wall thickness, and the pipe is simultaneously stretched in the axial direction to form it into the prescribed length. Then a punch having its diameter slightly larger than that of the punch 16 is pressed into the pipe 7C in a cold state to uniformly press only the surface of the inner peripheral surface of the pipe 7C, thereby forming a specular surface.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a metal pipe used, for example, in the front fork of a motorcycle.

Conventionally, the method for manufacturing a metal pipe as described in the above example involves pressurizing one end of a metal pipe having a required length r to form an enlarged diameter portion, and providing the enlarged diameter portion as a connecting portion with other parts. The inner circumferential surface had a completely precisely finished surface because it contained a vimeton that could be slid freely.

However, with this manufacturing method, the entire length of the gold IA4 pipe becomes as thick as the enlarged diameter part, which requires a thick wall for strength reasons, and the metal pipe sword (1 breast is large). Ta.

Therefore, it is also possible to connect the J finger-like body corresponding to the enlarged diameter part to the metal pipe of LTV flesh by full welding, but in this case, thermal distortion and assembly are likely to occur. I had a problem.

In addition, in order to form the inner peripheral surface of the metal pipe into a precise finish, polishing such as forming process 11. Not only is it a heavy burden when producing gold/i,% pipes, but it also requires forming processes in addition to drawing processes, which inevitably increases costs.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for manufacturing a metal pipe that does not impose a heavy load on the metal pipe and does not require forming processing or the like.

According to this invention, it is possible to form a lightweight metal pipe of a predetermined length using a short length of metal/tube, and moreover, it is possible to form a pipe of each part required for construction. ,!
It can be shaped into a wall thickness that corresponds to the size. In other words, if you use a 4A x size metal 1 and a similar pipe to form the enlarged diameter part VC with one end thick and blank, then draw the remaining vibrator part and stretch the entire length of the pipe to form it to the specified length. 7. Thin-walled gold j
A high pipe? 4 times, the overall weight is actually 1111
1i.

For this reason, not only will the cost of kidnapping be reduced, but the current situation of the warehouse will also be reduced.
: +li7; It can be reduced by 1, which is extremely beneficial.

- Also, as the final kneading, the inner periphery of the pipe [(r i V , compared to that, the pattern 9 machining with a small degree of machining'
It is possible to obtain a precision finish without the need for a forming process.

Because of this, the gold-plated pipes for front forks, etc. can not only be made by a series of drawing processes using a die punch, but also the enlarged diameter parts, which require thick walls, can be
Metal pipes are manufactured by using fc manufacturing means to accommodate thick walls, and to form thin walls for other pipe sections where thin walls are desirable, and to accommodate sections with different wall thicknesses. be able to.

An embodiment of the present invention having such features will be described in detail below with reference to the drawings.

Fig. 1 shows the entire steering stem of a motorcycle, and the front forks 1. The upper part of the front fork 1.1 is attached to the hand V part (not shown), and the lower end entrance part of the front fork 1.1 is connected to a hydraulic slackener.

Next, a method for manufacturing the metal pipe used in the above-mentioned front fork IK will be explained.

FIG. 2 shows the first drawing step, with the first enlarged diameter portion 4' on the two-end open surface 171! ! - a first mold having five holes;
A dynu 6 is provided, and gold k as a short material is placed in this first mold hole 5! Punch pipe 7 cold with @l punch 8, and
Strangulation is performed. As a result, the upper end of the metal pipe 7a is formed to have an enlarged diameter as the smoothly formed first enlarged diameter portion 4VC, and the lower part is narrowed to a small diameter by the first mold hole 5.

Then, the pipe 7a which has completed the first drawing step is further moved to the second drawing step 1, where it is formed into a completely enlarged diameter 111.

That is, 9. ') As shown in Figure 3, the second mold hole 10 of the second die 11, which has 10 holes with an enlarged diameter of ('') 52 and an enlarged diameter of 1?・
, 6 pipe 7a'7 cold [1) j with second punch 12 I
J-person and 8fN 2 &ji are performed. As a result, a completely enlarged diameter portion is formed at the upper end of 4f (1<r, +vibe'I b). 13 is a lower pressure member, and the extension and wall thickness of the molded IRIV pipe are The first and second punches 8, 12 mentioned above are the enlarged diameter portions 4, 12 of each die 6.11.
It is molded into a V shape corresponding to No. 9.

Then, as shown in FIG. 4, the third mold hole 14 is filled with the third die 15, and the second drawing die dk is finished/this metal pipe 7b? I: Cold press-fitting is performed using the third punch 16, and third drawing is performed. At this time, the third punch 16 presses the inner peripheral surface of the pipe by pressing the inner hole r of the pipe.
・The inner peripheral surface of the 4-pipe 7C is formed to have an enlarged diameter and a thin wall, and is also formed by being stretched to a constant length in the axial direction K iJi' of the pipe t.

Then, as shown in the 51st = 41 VC, the fourth mold hole 17
After completing the third drawing process, the fully bent pipe 7c'2 having a tray is press-fitted with the fourth punch 19, which has a larger diameter than the third boner 16, and the fourth drawing process is completed. It is done. At this time, the fourth punch 19 is inserted 31''i with the inner circumferential surface of the pipe lightly pressurized, so that only the surface of the inner circumferential surface of the pipe is uniformly pressurized and a red-colored surface is formed.

Like this, the first to fourth series of drawing steps? I: A predetermined metal pipe 7d is then formed.

The above-mentioned metal pipe is made of steel, aluminum alloy, etc., which is suitable for the shaft of the front flap, etc.

Further, the material thickness and raw length of the metal pipe are set to be the same as the molding thickness of the enlarged diameter portion, and are set to a length determined in advance by the length t of the pipe to be stretched after molding.

Note that in the above-mentioned embodiment, rj' first . The second pattern forming process is followed by metal pipe molding, but this is not the only option.If the first and second patterning processes can be formed in one process, one pattern can be formed in the first process. It is also possible to simplify the process in various ways.

[Brief explanation of the drawing]

Figure rl'li shows all examples of this origin, 1st page 1
Nutearing stem 7 used in J2 and J motorcycles
FIG. Fig. 2 shows a manufacturing method 4 of a metal pipe corresponding to the front fork of the steering stem. 1 song diagram. FIG. 4 is a sectional view of the kit showing the third drawing process. FIG. 5 is a cross-sectional view showing the fourth drawing process in progress. 4.9... Expanded diameter 111 5.10, 14.17... Mold hole 6.11, 15.18... Dia, 7.7a, 7b, 7c, 7d -- Gold strip i ,i Bahia"8.12,16.19...Ponchi Figure 1 Figure 3

Claims (1)

[Claims] 1. A metal pipe is press-fitted into a mold hole of a die having a mold hole 2 having an enlarged diameter portion at one end, and an enlarged diameter portion is formed at one end of the pipe. All other pipe parts are subjected to drawing 9 in the next process, and the total length of the pipe is r.
Stretched and formed into VOW meat, then inside the pipe 1ii'
Gold 1 is characterized by applying J & D processing with a small degree of processing to the ii side and forming the 11" d side inside the pipe with a mirror.
116 Method of manufacturing pipe.