The invention relates to a method for producing poppet valves, the method including: cross-wedge rolling a preform (2), which has at least one disk portion (4) and a shaft portion, to produce a valve blank (10), wherein a diameter of the shaft portion (6) is reduced substantially to a shaft diameter of a shaft (16), and additionally a length of the shaft portion (6) is increased substantially to a length of the shaft (16) by means of a rolling-out process.

The present invention discloses a rolling-bulging forming hydraulic machine for tubular products, which includes a frame. The frame is provided with an upper rolling mechanism, a lower rolling mechanism, a fixed liquid bulging hydraulic cylinder and a movable liquid bulging hydraulic cylinder. The upper rolling mechanism and the lower rolling mechanism are arranged oppositely, and the upper rolling mechanism and the lower rolling mechanism are used to roll surfaces of a to-be-machined tubular product. The fixed liquid bulging hydraulic cylinder and the movable liquid bulging hydraulic cylinder are arranged oppositely, and the fixed liquid bulging hydraulic cylinder and the movable liquid bulging hydraulic cylinder are used to perform hydraulic bulging on the to-be-machined tubular product.

A tubular structure includes a tube member provided with annular protrusions, on a side of an insertion opening that is a tube end part or a receiving opening and, on an outer circumference of the tube member, ring members, arranged on an opposite side of the tube end part with respect to the annular protrusions, having two side surfaces that are vertical with respect to an axis of the tube member.

A tubular structure includes a tube member provided with annular protrusions, on a side of an insertion opening that is a tube end part or a receiving opening and, on an outer circumference of the tube member, ring members, arranged on an opposite side of the tube end part with respect to the annular protrusions, having two side surfaces that are vertical with respect to an axis of the tube member.

Provided are a hollow drive shaft using an upsetting method and a method of manufacturing the same, in which hot forging and upsetting processes are applied to both ends of a workpiece so that an outer diameter at both ends of the workpiece is greater than an outer diameter of a middle part of the workpiece, thereby reducing a weight of the drive shaft and enabling the drive shaft to transmit higher driving power. According to the present invention, the upsetting process is applied during the hot forging process to manufacture the hollow drive shaft, portions to be substantially processed are limited to portions at both ends of the workpiece, and the number of upsetting processes is limited to a minimum number (2 or the like), such that initial investment costs and manufacturing costs are low because the number of processes is small.

A die matching system which is preferably implemented in die rolling machinery for fasteners employs witness or reference marks on each of the dies. An eddy current sensor is employed to sense the witness marks and to detect change in the relative position of the witness mark and hence the position of the rotatable dies. The change in position is then processed and a signal is transmitted to servo motors to change the relative position of the dies to compensate for the position changes continuously during the operation of the die rolling machinery. In one preferred form, the witness mark is in the form of a recess milled into the bottom end surface of the cylindrical die.

The invention relates to a method for shaping a workpiece having a drum-type peripheral wall, on the inner face of which an inner profile featuring longitudinal ribs is formed by feeding at least one profiling roll to said inner face. According to the invention, at least one rotatably mounted profiling roll is fed to an inner face of the peripheral wall of the workpiece, and said at least one profiling roll rotates relative to the inner face of the peripheral wall such that the inner profile is formed in the inner face in a non-cutting manner.

The invention relates to a method for shaping a workpiece having a drum-type peripheral wall, on the inner face of which an inner profile featuring longitudinal ribs is formed by feeding at least one profiling roll to said inner face. According to the invention, at least one rotatably mounted profiling roll is fed to an inner face of the peripheral wall of the workpiece, and said at least one profiling roll rotates relative to the inner face of the peripheral wall such that the inner profile is formed in the inner face in a non-cutting manner.

A device for forming circumferential grooves in pipe elements uses multiple geared cam bodies mounted on a carriage which rotates about a fixed pinion. The gears engage with the pinion which causes the geared cam bodies to rotate relative to the carriage. Traction surfaces and cam surfaces on the cam bodies traverse the outer surface of the pipe element and impress a circumferential groove therein. To substantially prevent rotation of the pipe element the pitch circle diameter of the pinion equals the outer diameter of the pipe element and the pitch circle diameters of the traction surfaces equal the pitch circle diameters of the gears.

A device for forming circumferential grooves in pipe elements uses multiple geared cam bodies mounted on a carriage which rotates about a fixed pinion. The gears engage with the pinion which causes the geared cam bodies to rotate relative to the carriage. Traction surfaces and cam surfaces on the cam bodies traverse the outer surface of the pipe element and impress a circumferential groove therein. To substantially prevent rotation of the pipe element the pitch circle diameter of the pinion equals the outer diameter of the pipe element and the pitch circle diameters of the traction surfaces equal the pitch circle diameters of the gears.