Rear swing arm of motor-bike with tapered rectangular pipe member and method of manufacturing tapered rectangular pipe for vehicle body

A method for manufacturing a tapered rectangular pipe for a vehicle comprising the steps of forming the tapered rectangular pipe into the rectangular raw pipe by an extrusion forming under any optional irregular thickness condition in a first step. Then the rectangular raw pipe is reduced to form a tapered part to make a tapered, irregular thickness, rectangular pipe member in a second step.

If you were to search for Rear swing arm of motor-bike with tapered rectangular pipe member and method of manufacturing tapered rectangular pipe for vehicle body using relaxed search criteria, these patents would come up:

What is claimed:

1. A method of manufacturing a tapered rectangular pipe for a vehicle comprising the steps of:

first, extruding a rectangular raw pipe having a rectangular sectional surface and an inner space being defined within the rectangular raw pipe, wherein the inner space of the rectangular raw pipe being divided into a plurality of segments byintegral partition walls extending in a longitudinal direction within the inner space of the rectangular raw pipe; and

second, forming at least a partial wall surface of the rectangular raw pipe into a tapered shape in a longitudinal direction without folding the partial wall, wherein at least two chambers are formed within the rectangular raw pipe by theintegral partition walls, each of the at least two chambers having side walls and one of the chambers having a tapered wall surface and one of the chambers being without a tapered wall surface, in which a side wall of the one chambers without a taperedwall surface is made with a thinner wall thickness than a side wall of a chamber having a tapered wall surface.

2. The method of manufacturing a tapered rectangular pipe for a vehicle as set forth in claim 1, wherein the rectangular raw pipe includes upper, lower, left-side and right-side walls and wherein the rectangular raw pipe in the first step isformed with an irregular wall thickness with at least a partial wall surface of at least one of the upper, lower, left-side and right-side walls having a longitudinal rectangular sectional shape which is thicker than that of the other walls to thereforeprovide a thick wall part.

3. The method of manufacturing a tapered rectangular pipe for a vehicle as set forth in claim 2, wherein both upper and lower walls are made thicker than those of the right-side and left-side walls.

4. The method of manufacturing a tapered rectangular pipe for a vehicle as set forth in claim 2, wherein the thick wall part has an integral rib extending in a longitudinal direction to one of an inner wall and an outer wall.

5. The method of manufacturing a tapered rectangular pipe for a vehicle as set forth in claim 1, wherein two chambers are formed as the at least two chamber within the rectangular raw pipe with a first one of the two chambers having the taperedwall surface and a second one of the two chambers being without the tapered wall surface, the side wall of the second chamber being made thinner than the side wall of the first chamber during the second step of forming.

6. The method of manufacturing a tapered rectangular pipe for a vehicle as set forth in claim 1, wherein three chambers are formed as the at least two chamber within the rectangular raw pipe with a first and third one of the three chambershaving the tapered wall surfaces and with a second one of the three chambers being without the tapered wall surface, the side wall of the second chamber being made thinner than the side wall of the first and third chambers during the second step offorming.

7. The method of manufacturing a tapered rectangular pipe for a vehicle as set forth in claim 1, wherein the step of forming a tapered surface is carried out by a non-rotary swagging.

8. The method of manufacturing a tapered rectangular pipe for a vehicle as set forth in claim 7, wherein the rectangular raw pipe in the first step is formed with an irregular wall thickness with at least a partial wall surface of at least oneof the upper, lower, left-side and right-side walls having a longitudinal rectangular sectional shape which is thicker than that of the other walls.

9. The method of manufacturing a tapered rectangular pipe for a vehicle as set forth in claim 1, further comprising the steps of:

welding another component to the rectangular pipe; and

providing a recess in one of the another component and the rectangular pipe, burrs formed when the another component element is welded to the rectangular pipe being overlapped and received in the recess.