Abstract: The present invention relates to a machine for injection molding of rubber products, comprising a plurality of molding units to be operated separately for carrying out a molding cycle. The molding units are mounted on a common support and each unit receives the rubber blend to be used in molding through a duct branched off from a channel fed by a common injection unit. The branched-off feeding ducts of the units are intercepted by a dispensing element moved step by step to sequentially open a predetermined number of the branched-off ducts, so that the corresponding molding units are driven to receive the rubber to be introduced into the mold for execution of molding.

Abstract: An open mill or mixer for the processing of rubber and plastics comprises an additional or third roll for a higher productivity and, when upstream of the open mill a closed mixer is provided, for a readier cooling of the mixture. The two usual rolls are not placed at the same level, but one is slightly upper, while the third additional roll engages the lower one in the bottom part thereof. The angle formed by the lines joining the center of this latter with the centers of the other two rolls is comprised between 60.degree. and 120.degree. and is preferably of 80.degree.-90.degree.. Also the third roll is motor-driven, as well as the other two and has a higher peripheral speed than the roll which is wrapped up by the mix sheet and has the lower speed.