Abstract: A hard outer member generally centered on an axis and having a concave inner surface is injection molded of a relatively hard synthetic resin to have on its inner surface at one end a recess formed with a radially throughgoing passage. Parts of the mold in which this member is molded are then displaced before the resin has time to cure and another softer synthetic resin injected through this radially throughgoing passage to form in the recess a relatively soft seal having a sprue extending through the passage. The seal therefore adheres in surface contact with the inner surface at the recess and the sprue further ensures excellent holding of the seal on the member.

Abstract: A rapid-change system for injection-molding machine has a pair of adapter plates secured to the respective mold parts which engage in guides of the mold-carrying plates of the machine so that nothing projects outwardly beyond these adapter plates. Locks on the mold-carrying plates hold the adapter plates in position and the plates can be provided with service fittings which interconnect and disconnect upon insertion and removal of the molds together with the respective adapter plates.

Abstract: An injection-molding machine whose mold-carrying plates are provided with quick-release locking devices for engagement with adapter plates on respective halves on the mold, also has at least one of the plates provided with a horizontal transverse guide for the mold whereby the mold can be inserted laterally and removed laterally. A carriage is displaceable along the machine and has roller conveyors and a device for drawing a mold from the machine onto the roller conveyor or pushing a mold from a roller conveyor onto the machine.

Abstract: A hard outer member generally centered on an axis and having a concave inner surface is injection molded of a relatively hard synthetic resin to have on its inner surface at one end a recess formed with a radially throughgoing passage. Parts of the mold in which this member is molded are then displaced before the resin has time to cure and another softer synthetic resin is injected through this radially throughgoing passage to form in the recess a relatively soft seal having a sprue extending through the passage. The seal therefore adheres in surface contact with the inner surface at the recess and the sprue further ensures excellent holding of the seal on the member.