Abstract: A tool bit has a body (1) with an axially extending insertion end (2) for insertion into a chuck on a drive unit. The insertion end (2) has closed ended axially extending grooves (4) and axially extending grooves (5) open at the trailing end of the insertion end. The open end grooves have a base (6) with a shaped configuration (7). The shaped base has depressions or recesses (8) forming stop faces (9) extending transversely of the axial direction and acting essentially in the axial direction of the insertion end. When the insertion end (2) is placed into the chuck, any dirt on the stop faces (9) can be wiped off and deposited in the recesses (8). The shaped configuration (7) of the base (6) prevents, during formation of the axially extending grooves (4, 5), by means of grooving tools rolling in the axial direction of the insertion end (2), any undesirable length changes in the insertion end while affording sharp-edges rolling of the shaped configuration.

Abstract: Grooves are formed in an insertion end of a working tool, such as a tool bit or a chisel bit by pivoting a grooving tool about a pivot axis extending perpendicularly to the axis of the insertion end. By pivoting the grooving tool about the pivot axis, it moves along the axial direction of the insertion end forming the grooves. A plurality of the grooving tools can be ganged together and moved by a single drive unit for simultaneously forming angularly spaced grooves in the insertion end.

Abstract: A composite piston for ejecting a plastic mass from a receptacle includes a piston head and a pressure component which in combination form a chamber. The piston head and pressure component are displaceable within the receptacle from an insertion position into a locked position. When being moved into the locked position, a part of the plastic mass flows through an opening in the piston head into the chamber. After the locked position is established, the opening in the piston head is closed by an extension on the pressure component.