Abstract: A cylinder tube comprising an aluminum tube formed on its outer surface with an outside oxide film having a hardness of not lower than 150 HV to less than 350 HV and on its inner surface with an inside oxide film having a hardness of not lower than 350 HV to not higher than 650 HV.

Abstract: In brazing a first metal piece having a tubular joint portion of predetermined length at an end thereof and a second metal piece having a bore for inserting the extremity of the joint portion thereinto by replaced brazing with the extremity of the joint portion inserted in the bore, a plurality of axial grooves having a depth of 0,3 to 1,5 mm and arranged at a spacing of 5 to 30 mm in the circumferential direction are formed in the outer peripheral surface of joint portion of the first metal piece. Each of the grooves has one end extending to the outside of the bore of the second metal piece when the joint portion is inserted in the bore. The gas or residue of flux produced during brazing escapes through the grooves, whereby voids or like defects are prevented from occurring in the fillet of the brazed joint. Since the grooves are all filled up with the brazing filler metal, the brazed joint is given a sufficient bond strength and prevented from permitting leakage there-through.

Abstract: An aluminum pipe according to the present invention is used in forming a plurality of bulged portions on the peripheral wall thereof. At the same time by bulging has been so refined as to exhibit an elongation of at least 40% and a recrystallization texture of up to 60 .mu.m in grain size during bulging. The aluminum pipe to be bulged is produced by a process characterized by drawing an extruded aluminum pipe at a cold working ratio of at least 40%, and thereafter annealing the drawn pipe at a temperature of 350.degree. to 420.degree. C., whereby the pipe is refined to exhibit the specified elongation and recrystallization texture.

Abstract: An intake manifold adapted for use with an engine having two intake ports for each cylinder incorporates an aluminum plenum chamber having an air inlet and air outlets twice the number of cylinders of the engine in number, and a plurality of branch pipes of wrought aluminum connected to the respective air outlets of the plenum chamber. One of the two branch pipes to be connected to the intake ports for each cylinder is larger in the length of the channel than the other branch pipe. The two branch pipes are equal in the cross sectional area of the pipe channel, or the branch pipe having the longer channel is smaller than the other branch pipe in the cross sectional area of the channel. The roughness of the inner surface of each branch pipe is up to 10 .mu.m, preferably up to 5 .mu.m, more preferably up to 1 .mu.m, in terms of center line average height.

Abstract: The invention is drawn to an intake manifold for an internal combustion engine. The manifold is made of an aluminum plenum chamber having an air inlet and a plurality of air outlets with a plurality of wrought aluminum branch pipes extending from the respective plenum outlets. The branch pipes have an inner peripheral surface of circular cross section. At least one of the branch pipes is deformed at an intermediate portion along its length thereby forming a clearance area so that the branch pipe is free from contact with the adjacent branch pipe.

Abstract: An intake manifold adapter comprising an adaper body made of aluminum and having a gas channel adapted to communicate at its one end with the outlet of a throttle body for holding an air cleaner in communication with an intake manifold and at the other end thereof with the inlet of the manifold, and an exhaust gas inlet pipe having an aluminum portion at its one end and a stainless steel portion secured thereto and providing the other end of the pipe, the inlet pipe being fixed to the adapter body by the aluminum portion being metallurgically joined to the body, the stainless steel portion providing a joint for a pipe for returning the exhaust gas from an engine to the manifold.

Abstract: A process for producing a chassis for vehicles, which includes the steps of fabricating a single frame element of aluminum alloy, the frame element having an upper beam, a lower beam and a web portion connecting between the two beams, removing some of the web portion to a desired length, pulling the upper beam and lower beam of the web vacant portion in opposite directions so that the web vacant portion becomes an expanded opening, bending the frame element in accordance with the size and shape of the body of a vehicle to be placed on the chassis, and welding the terminating ends of the frame element to form an endless frame.

Abstract: A process for producing an intake manifold having a main pipe made of wrought aluminum material and having an open end, a closed end opposite to the open end, a plurality of holes formed in its peripheral wall and outward tubular projections integral with the peripheral wall and each formed around each of the holes, and a plurality of branch pipes made of wrought aluminum material and each having one end fitting in and joined to each of the tubular projections. The manifold is smooth-surfaced in its interior, diminished in resistance to air and improved in air intake efficiency. The manifold requires no finishing procedure unlike those prepared by casting.

Abstract: An intake manifold comprising a main pipe made of wrought aluminum material and having an open end, a closed end opposite to the open end, a plurality of holes formed in its peripheral wall and outward tubular projections integral with the peripheral wall and each formed around each of the holes, and a plurality of branch pipes made of wrought aluminum material and each having one end fitting in and joined to each of the tubular projections. The manifold is smooth-surfaced in its interior, diminished in resistance to air and improved in air intake efficiency. The manifold requires no finishing procedure unlike those prepared by casting.

Abstract: A fuel pipe device for motor vehicles comprising a pipe main body having a plurality of holes formed in its peripheral wall and outward tubular projections each formed around each of the holes integrally with the wall for connecting branch pipes to the pipe main body. The device is produced by a process comprising bulging the peripheral wall of a pipe blank at each of the portions thereof to be connected to the branch pipes to form a tubular protrusion having a closed end, forming a hole in the center of the end closing wall of the protrusion, and bending the remaining portion of the end closing wall around the hole outward by burring flush with the peripheral wall of the protrusion to form the tubular projection. Alternatively, the device is produced by a process comprising forming a hole in a pipe blank at each of the portions thereof to be connected to the branch pipes, and bending the hole-defining portion of the blank outward by burring to form the projection.

Abstract: A method for producing aluminum drums having highly smooth surfaces, the method including two steps; the preparation of an aluminum pipe by extrusion, and the drawing of the pipe through a die unit, wherein the die unit comprises a die and a plug, the die having an approach angle of 45.degree. to 75.degree. C. and the plug having an approach angle of 10.degree. to 20.degree..

Abstract: An apparatus for continuously producing a tube having helical grooves in its inner surface comprising a tube twising rotary frame, a pay-off drum mounted on the rotary frame for paying off a tube having straight grooves in its inner surface, a nozzle provided at the front end of the rotary frame and having an adjustable inside diameter for sending out the paid-off tube forwardly of the rotary frame, and at least one pair of catching rollers provided in front of the rotary frame and disposed close to the nozzle for holding the sent-out tube. Each of the catching rollers is formed in its peripheral surface with a groove of semicircular cross section in conformity with approximately one-half of the outer periphery of the tube. With the rotation of the rotary frame, the straight-grooved tube is twisted between the nozzle and the catching rollers, whereby the straight grooves are deformed to helical grooves.