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An assembly retainer for a self-aligning pelletizer cutter hub having a self-aligning driving connection between a cutter hub and a drive shaft for the hub in which the cutter hub is capable of universal pivotal movement as well as a driving connection through diametrically located recesses and sphe

An assembly retainer for a self-aligning pelletizer cutter hub having a self-aligning driving connection between a cutter hub and a drive shaft for the hub in which the cutter hub is capable of universal pivotal movement as well as a driving connection through diametrically located recesses and spherical balls. The retainer is supported on the hub to retain the torque transmitting balls in the recesses. In one embodiment, the balls are retained by circular plates attached to the hub in position to form a closure for an open end of each recess. In another embodiment, spring pins are inserted in passageways in the hub with one end extending into an open end of said recesses to form an obstruction in each recess.

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1. A self-aligning cutter hub assembly for use in an underwater pelletizer connected to a drive shaft and enabling cutter blades on a cutter hub to be aligned with and move in parallel relation to a die face on an extrusion die plate, said cutter hub assembly comprising a centrally located axial bor

1. A self-aligning cutter hub assembly for use in an underwater pelletizer connected to a drive shaft and enabling cutter blades on a cutter hub to be aligned with and move in parallel relation to a die face on an extrusion die plate, said cutter hub assembly comprising a centrally located axial bore defined by an inner surface on said cutter hub, said inner surface of the bore being partially spherical, an adapter rigidly mountable on an end of said drive shaft and received in said bore, said adapter including a partially spherical outer surface with the partially spherical surfaces being closely related and matching each other, each of the partially spherical surfaces including a pair of recesses each receiving a torque transmitting element partially received in each of the recesses in the matching surfaces to drivingly connect the hub to the drive shaft and enable pivotal movement of the hub on said end of said drive shaft, and a removable retainer on said cutter hub which forms an obstruction for an open end of each of said recesses in the hub to retain said elements in said recesses by direct contact with said elements when said adapter is in perpendicular relation to said shaft. 2. The cutter hub assembly as defined in claim 1, wherein said torque transmitting element is a spherical ball. 3. The cutter hub assembly as defined in claim 1, wherein said retainer is a plate mounted on said hub and forming said obstruction at an outer end of said recess in the hub to retain said torque transmitting element in the recess. 4. The cutter hub assembly as defined in claim 1, wherein said retainer includes a spring pin inserted into an angled passageway with one end of the pin extending into said open end of the recess in the hub to prevent the ball from exiting the recess. 5. The cutter hub assembly as defined in claim 1, wherein said partially spherical surface in the cutter hub includes an axial semicylindrical recess extending from an end surface of said cutter hub, said partially spherical surface in the cutter hub including recesses extending circumferentially to both sides of the semicylindrical recess in the cutter hub to enable insertion of the partially spherical surface of the adapter into cutter hub bore when the adapter is oriented in 90° relation to the cutter hub bore with the semicylindrical recess receiving the torque transmitting element and the circumferential recesses receiving the partially spherical surfaces on the adapter to enable assembly of the adapter by moving it inwardly into the bore when in an 90° relation to the cutter hub and then pivoting it 90° to orient the partially spherical surfaces in registry with each other. 6. A self-aligning tatter hub drivingly connected to a drive shaft to enable the hub to pivot universally in relation to a rotational axis of the drive shaft, said hub including a bore therethrough having an inner surface provided with an arcuate curvature having a center at the center of the hub, an adapter mounted on said drive shaft and received in said bore, said adapter having an arcuately curved outer surface having a center at the center of the hub, said inner surface of the bore terminating at an end surface of the bore, said outer surface of the adapter terminating at end edges of said adapter to enable relative angular movement of the hub as the edge portions of the adapter move out of alignment with the end surfaces of the hub and torque transmitting members interconnecting the outer surface of the adapter and the inner surface of the hub bore, said torque transmitting members being spherical balls partially received in recesses in each of the curved surfaces and a retainer associated with each ball receiving recess in said hub bore to retain the balls in the recesses by direct contact with said balls when said adapter is removed from said shaft and pivoted into perpendicular relation to said hub. 7. The hub as defined in claim 6, wherein the external surface of the adapter includes a pair of semispherical recesses, the internal surface of the bore including axial recesses receiving the torque transmitting balls and enabling insertion of the exterior surface of the adapter into the interior surface of the bore when the adapter is at 90° to the bore with the adapter being rotated 90° to be received within the bore with the matching curved surfaces and the torque transmitting balls retaining the adapter in the bore after assembly, said retainer including an obstruction in an open end portion of each axial recess in the internal surface of the bore to prevent the balls from exiting the recesses in the bore by direct contact of said retainer with said balls. 8. The hub as defined in claim 7, wherein said obstruction comprises a retainer member secured in closing relation to an open end of said recesses in the interior surface of said hub bore to retain said balls in said recesses. 9. The hub as defined in claim 8, wherein said retainer member is a circular plate secured in place by a screw threaded fastener threaded into said hub. 10. The hub as defined in claim 7, wherein said obstruction comprises spring pins inserted into angled passageways in said hub, said pins extending into the open end of said recesses to retain said balls in said recesses in said hub. 11. In combination, a self-aligning cutter hub for connection with a drive shaft to enable the hub to pivot universally in relation to a rotational axis of the drive shaft, said hub including an inner surface provided with an arcuate curvature, an adapter drivingly connected to the drive shaft, said adapter having an arcuately curved outer surface engaged with said arcuately curved inner surface on the hub to enable pivotal movement of the hub in relation to the adapter, and torque transmitting structure interconnecting the outer surface of the adapter and the inner surface of the hub for driving said hub, and a retainer associated with said hub and adapter to retain said torque transmitting structure in assembled interconnected relation to the hub and adapter. 12. The hub as defined in claim 11, wherein said torque transmitting structure includes a pair of torque transmitting members diametrically opposed on the arcuately curved outer surface of the adapter, the arcuately curved inner surface of said hub including a pair of diametrically opposed axial recesses aligned with and receiving said torque transmitting members on said outer surface of the adapter, each of said recesses in the inner surface of the hub having an open end extending to one end of the hub to enable insertion of said torque transmitting member on the adapter when the outer surface of the adapter is engaged with the inner surface of the hub, each recess in the inner surface of the hub having an inner closed end spaced inwardly from the open end of the recess, said open end of the recesses in the inner surface of the hub enabling axial insertion of the adapter and torque transmitting members, said retainer including an obstruction for each of said recesses outwardly of said torque transmitting members to retain the torque transmitting members from moving through the open ends of said recesses. 13. The hub as defined in claim 12, wherein said torque transmitting members are spherical balls received in semispherical recesses on the curved outer surface of the adapter, said recesses in the inner surface of the hub being substantially semicylindrical to enable insertion of said adapter and said balls into the recesses in the inner surface of the hub, said obstruction being in the for of a plate forming a closure for said open end of each of said recesses in the hub. 14. The hub as defined in claim 12, wherein said torque transmitting members are spherical balls received in semispherical recesses on the curved outer surface of the adapter, said recesses in the inner surface of the hub being substantially semicylindrical to enable insertion of said adapter and said balls into the recesses in the inner surface of the hub, said obstruction being in the form of a pin inserted into each of said recesses between said balls and the open end of said recesses on the inner surface of the hub to prevent the torque transmitting balls from exiting the recesses in the hub. 15. In an underwater pelletizer including a die plate having a plurality of extrusion orifices terminating at a die face, a cutter assembly mounted on a drive shaft for rotating the cutter assembly in facing relation to the die plate, said cutter assembly including a plurality of cutting elements movable in close parallel relation to the die face for cutting plastic extruded from the orifices into pellets, said cutter assembly including a hub mounted on the drive shaft in a manner to enable substantial universal pivotal movement in relation to the drive shaft for self-alignment of the cutting elements with the die face, said hub including a bore therethrough at the center thereof, said bore having an inner face with a partial spherical surface, and an adapter mounted on said drive shaft, said adapter having a partial spherical curved outer surface, said adapter being received in said bore with the partial spherical surfaces being in opposed relation to enable substantial universal pivotal movement of the hub in relation to the drive shaft, each partial spherical surface including opposed recesses receiving torque transmitting spherical balls to drive the hub while permitting said substantial universal pivotal movement, each of said recesses in the curved outer surface of the adapter being substantially semispherical for receiving a portion of one said torque transmitting ball, said recesses in the inner surface of the bore being substantially semicylindrical to enable insertion of said adapter and said balls into the recesses in the inner surface of the bore, each of said recesses in the inner surface of the bore having a partial spherical inner end for engaging a portion of one said torque transmitting ball and an open end opposed to said inner end, each of said semicylindrical recesses including lateral recesses extending a short distance circumferentially in the inner surface of the bore from opposite edges of the semicylindrical recesses to enable the outer curved surface of the adapter to be inserted into and removed from the inner curved surface of the bore when the adapter is in perpendicular relation to said hub, said torque transmitting balls being capable of exiting from said open ends of said semicylindrical recesses and said torque transmitting balls being subject to dropping out of said semispherical recesses in the adapter when said adapter is perpendicular to said hub, said adapter being rotatable into alignment with the hub such that the partial spherical surfaces on the adapter and in the hub bore retain and support the hub on the adapter and a removable ball retainer adjacent each said semicylindrical recess to block exiting movement of said balls from the semicylindrical recesses when the adapter is in said perpendicular relation to the hub thereby retaining the hub and adapter in assembled relation. 16. The structure as defined in claim 15, wherein said semispherical recesses and lateral recesses in the bore of said hub and the semispherical recesses in said adapter enable pivotal movement of the adapter between aligned relation to the hub to perpendicular relation to the hub when assembling and disassembling said hub and adapter. 17. The structure as defined in claim 15, wherein said ball retainer includes a pin inserted into each semicylindrical recess between the ball and the open end of each semicylindrical recess to block exiting movement of the balls when the adapter is perpendicular to said hub. 18. The structure as defined in claim 15, wherein said ball retainer includes a plate positioned in overlying relation to the open end of said semicylindrical recesses and removably secured to said hub to block exiting movement of the balls when the adapter is perpendicular to said hub.