The invention relates to a twist-axle that includes a cross-beam member and two trailing arms, each trailing arm rigidly secured to the cross-beam member in one of two connection regions of the cross-beam member or formed integrally with and extending from one of the two connection regions. The cross-beam member is formed from a tubular blank and has a torsionally elastic central portion and two torsionally stiff connection regions. The cross-beam member has a wall thickness that varies longitudinally along the length of the cross-beam member from the torsionally elastic central portion to each of the torsionally stiff connection regions.

The invention relates to a twist-axle that includes a cross-beam member and two trailing arms, each trailing arm rigidly secured to the cross-beam member in one of two connection regions of the cross-beam member or formed integrally with and extending from one of the two connection regions. The cross-beam member is formed from a tubular blank and has a torsionally elastic central portion and two torsionally stiff connection regions. The cross-beam member has a wall thickness that varies longitudinally along the length of the cross-beam member from the torsionally elastic central portion to each of the torsionally stiff connection regions.

A method for producing a shaft, in particular a balance shaft, crankshaft and the like, having at least one substantially annular bearing seat and at least one unbalance portion. The method includes the steps: provision of a shaft blank; formation of the at least one unbalance portion and of at least two opposite bearing seat side members by a forming process; and deformation of the at least two opposite bearing seat side members by a shell tool such that the bearing seat side members are bent together, whereby the at least one substantially annular bearing seat is formed.

A method for producing a shaft, in particular a balance shaft, crankshaft and the like, having at least one substantially annular bearing seat and at least one unbalance portion. The method includes the steps: provision of a shaft blank; formation of the at least one unbalance portion and of at least two opposite bearing seat side members by a forming process; and deformation of the at least two opposite bearing seat side members by a shell tool such that the bearing seat side members are bent together, whereby the at least one substantially annular bearing seat is formed.

A method of manufacturing a pipe member includes arranging a pre-pipe member between first and second dies, moving one of the first and second dies to be closer to another one and holding the pre-pipe member with first and second recess portions, by the moving of the one of the first and second dies, and pressing an outer peripheral surface of the pre-pipe member with first and second inner surfaces in a closed state of the dies. By the pressing of the outer peripheral surface of the pre-pipe member, reducing a diameter of a portion of the pre-pipe member and forming a reduction portion having a polygonal shape so that the reduction portion has a same number of outer surfaces as a total number of the first inner surfaces and the second inner surfaces.

A method of manufacturing a pipe member includes arranging a pre-pipe member between first and second dies, moving one of the first and second dies to be closer to another one and holding the pre-pipe member with first and second recess portions, by the moving of the one of the first and second dies, and pressing an outer peripheral surface of the pre-pipe member with first and second inner surfaces in a closed state of the dies. By the pressing of the outer peripheral surface of the pre-pipe member, reducing a diameter of a portion of the pre-pipe member and forming a reduction portion having a polygonal shape so that the reduction portion has a same number of outer surfaces as a total number of the first inner surfaces and the second inner surfaces.

Anchor pieces (1A, 1B) made of elongated metal plates (11) detachably contact each other to form an anchor (H) for a reinforcing bar (Rb) made of fiber-reinforced plastic to be used in prestressed concrete. Elongated holes (12) respectively extend in a width direction of each of anchor pieces at regular intervals in a longitudinal direction thereof. At least one locking half portion (13) is formed in each anchor piece by deforming an area (Y) between adjacent elongated holes and has a convex semicircular shape or quarter sphere shell shape. At least one annular locking portion (14) is formed by the at least one locking half portion of the two anchor pieces when the two anchor pieces are in contact with each other. The annular locking portion has a circular inner space in transverse cross-section and is configured to engage the reinforcing bar (Rb) when disposed therein.

Anchor pieces (1A, 1B) made of elongated metal plates (11) detachably contact each other to form an anchor (H) for a reinforcing bar (Rb) made of fiber-reinforced plastic to be used in prestressed concrete. Elongated holes (12) respectively extend in a width direction of each of anchor pieces at regular intervals in a longitudinal direction thereof. At least one locking half portion (13) is formed in each anchor piece by deforming an area (Y) between adjacent elongated holes and has a convex semicircular shape or quarter sphere shell shape. At least one annular locking portion (14) is formed by the at least one locking half portion of the two anchor pieces when the two anchor pieces are in contact with each other. The annular locking portion has a circular inner space in transverse cross-section and is configured to engage the reinforcing bar (Rb) when disposed therein.

A device and method for continuously producing an at least partly hollow shaft having a varying inner diameter includes forging tools that are arranged centrally symmetrically about a forging axis and are driven radially, a clamping chuck for holding an at least partly hollow cylindrical blank, and a counter-holder for axially supporting the blank. The counter-holder has a base and a counter-holder mandrel arranged on the base and extending axially into a central cavity in the blank. The mandrel is formed of at least two parts, wherein a first part of the counter-holder mandrel constitutes an inner part and a second part of the counter-holder mandrel constitutes an outer part surrounding the inner part. At least the outer part can be moved axially relative to the inner part.

A device and method for continuously producing an at least partly hollow shaft having a varying inner diameter includes forging tools that are arranged centrally symmetrically about a forging axis and are driven radially, a clamping chuck for holding an at least partly hollow cylindrical blank, and a counter-holder for axially supporting the blank. The counter-holder has a base and a counter-holder mandrel arranged on the base and extending axially into a central cavity in the blank. The mandrel is formed of at least two parts, wherein a first part of the counter-holder mandrel constitutes an inner part and a second part of the counter-holder mandrel constitutes an outer part surrounding the inner part. At least the outer part can be moved axially relative to the inner part.