Abstract: Disposed on a central machine portion (10) are two clamping devices (32,34), each for a respective body blank (P.sub.l,P.sub.r), and a welding device (20) for welding together overlapping margins of the blanks (P.sub.l,P.sub.r). Disposed one at each side of the central machine portion (10) are feed tables (80,82) on each of which a blank (P.sub.l R.sub.r) can be fed through one of the clamping devices (32,24), transversely to the proposed weld seam, into an overlapping position. A supporting device (50) is disposed between the two clamping devices (32,34) to support the margin to be welded of the blank (P.sub.l) fed in on one of the two feed tables (80). This supporting device can be moved out of a supporting position in which it supports the margin to be welded of the blank (P.sub.l) in question, into a position of rest in which it allows this margin to come to lie on the margin of the other blank (P.sub.r).

Abstract: A shot sleeve, for receiving a metered quantity of melt through an inlet or filling opening and connected to the mold cavity, has its volume continuously diminished in such a manner as to maintain a constant communication between the space above the melt in the shot sleeve and the mold cavity for escape of all the gas or air above the melt into the mold cavity before the opening of the shot sleeve into the mold cavity is completely closed by the advancing melt. This is effected, during the shot-pre-filling phase, by an accelerated motion of an injection piston from a rest position, at which the filling inlet to the shot sleeve is open, through the shot sleeve toward the mold cavity opening. As a result of the accelerated motion of the piston, the melt spreads over the melt engaging surface of the injection piston and the formation of a standing wave is prevented.

Abstract: In the method, a shot sleeve, for receiving a metered quantity of melt through an inlet or filling opening and connected to the mold cavity, has its volume continuously diminished in such a manner as to maintain a constant communication between the space above the melt in the shot sleeve and the mold cavity for escape of all the gas or air above the melt into the mold cavity before the opening of the shot sleeve into the mold cavity is completely closed by the advancing melt. This is effected, during the shot-pre-filling phase, by an accelerated motion of an injection piston from a rest position, at which the filling inlet to the shot sleeve is open, through the shot sleeve toward the mold cavity opening. As a result of the accelerated motion of the piston, the melt spreads over the melt engaging surface of the injection piston and the formation of a standing wave is prevented.