Abstract: A method of forming a golf ball includes forming a core using a 3D printer, and molding a cover in a surrounding position over the core through at least one of compression molding and injection molding. The core may be formed by printing a first core portion, printing a second core portion, and fusing the first core portion with the second core portion to form the core. Each of the first and second core portions may respectively include a plurality of concentric shells that are sequentially constructed.

Abstract: The present invention is directed towards a multi-layer golf ball cover formed by a sandwich injection molding process, wherein said golf ball cover comprises an inner layer and an outer layer of a first material and an intermediate layer therebetween of a second material. The present invention is directed towards a sandwich injection molding process for forming a multi-layer golf ball cover involving the steps of pushing a measured amount of a plasticized first material into one end of an accumulation cylinder, pushing a measured amount of a plasticized second material into the opposite end of the accumulation cylinder, and injecting both materials in a single plunging step, so that the first material substantially coats the surface of the mold while the second material substantially fills the interior of the first material.

Abstract: A method for making a ball for sports comprises providing a round rubber tube, forming a reinforcing layer of a yarn wound about the tube, forming a rubber cover layer formed on the reinforcing layer, and vulcanizing the rubber cover layer to provide a carcass. In the method, the reinforcing layer is formed by winding, in combination, a covered yarn made of a urethane elastomer core thread wound thereabout with a synthetic resin filament or in combination with the synthetic resin filament and a yarn made of a member selected from the group consisting of cotton, polyesters and polyamides. The carcass may be attached with a skin layer made of a natural or artificial leather. Alternatively, the round rubber tube having the reinforcing layer may be attached with a skin layer.