Abstract: A dual worm extruder includes a worm housing having a cavity and a wear resistant insert accommodated in the cavity. The insert has two parallel extruder bores defining, when viewed together in cross section, passages of circular areas having an overlap. The outer surface portions of the insert situated on opposite sides adjacent the overlap are peripherally concave, whereby the cross-sectional outline of the insert has the shape of an hourglass.

Abstract: A method of providing a wear-resistant layer on the inner bore faces of the housing of a dual-worm extruder having two longitudinally communicating parallel bores for accommodating extruder worms therein. According to the method, a relatively soft sheet metal blank and a relatively hard, wear-resistant sheet metal blank are metallurgically bonded to one another in a face-to-face relationship, then the thus obtained "sandwich" is deformed into two longitudinally open tubular blanks, with the relatively soft sheet metal blank forming the outer, convex side of each tubular blank. Thereafter, the tubular blanks are welded to one another along respective longitudinal edges thereof for obtaining a composite body having a cross-sectional outline of a FIG. 8, generally corresponding to, but being smaller than the cross-sectional outline of the bores.

Abstract: Process for coating foil material of any desired shape with an injectable and pressable mass which stabilizes the foil material. An initially planar heated foil material is pressed by means of a depressor against a movable mold member of an injection mold having a movable mold member and a stationary mold member, with the injection mold having a shape which corresponds to the later shape of the foil material. The foil material is then pulled against the surface of the movable mold member by subatmospheric pressure. Subsequently, the movable mold member is moved toward the stationary mold member of the injection mold to provide a gap between the foil material and stationary mold member and the mass is slowly injected into the gap remaining between the foil material and the stationary mold member. The two mold members are further closed to finally distribute the mass over the foil material and press the mass to the required thickness. An apparatus is provided for practicing this method.

Abstract: A die mold is disclosed for the manufacture of crate like containers having lateral walls at least the upper portion of which are double-walled to provide substantial stability to the container and strength to the container walls. The die mold includes a base plate, lateral wedges which move upwardly and downwardly at an angle to the vertical during opening and closing of the mold, and slider means which are positioned on the lateral wedges and are movable with respect to the lateral wedges in a reciprocal direction relative to the walls of the containers formed by the die mold. Holding means is provided for holding the slider means in the same position relative to the container during mold opening, and control means are provided to permit the slider means to move back from the container walls after the container has been moved a predetermined distance away from the base plate.