PURPOSE: To form a light groove-shaped part using a small quantity of material by drawing the center sections of tetragons to form a tapered shape after forming channel bars from a raw material having the side face sections connected to both ends of the center sections of the tetragons. ;CONSTITUTION: After stamping out channel bars 19 from a steel plate, when the end sections 43 and 44 are drawn outside and broadened by drawing the center sections 29 of the channel bars 19 in the direction of side face sections 31 and 32, the material of the center sections 29 is reduced in thickness due to drawing, and the longer the center section 29 is drawn, the more the thickness is reduced. That is, in the cross sections near the center section of the channel bar 19, the thickness of each of the center sections 29 is more or less reduced more than the thickness of each of the side face sections 31 and 32, and in cross sections adjacent to the end sections 43 and 44, the center sections 29 are drawn, becoming thin. In either before or after this drawing process, the side face sections 31 and 32 are bent orthogonally to the center section 29. This makes it possible to form a channel bar with tapered section using a small quantity of material and lighten the channel bar.;COPYRIGHT: (C)1995,JPO
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