초록 ▼

A method is illustrated for manufacturing bicycle cranks in which a layer of foamable material is applied on an outer surface of a metallic member which has two holes respectively defined in two ends thereof. A layer of composite preimpregnated material is then applied on the layer of foamable mater

A method is illustrated for manufacturing bicycle cranks in which a layer of foamable material is applied on an outer surface of a metallic member which has two holes respectively defined in two ends thereof. A layer of composite preimpregnated material is then applied on the layer of foamable material. Thereafter, the metallic member is mounted in a mold and then heated to make the foamable material foam, thereby achieving formation of a semi-product crank by means of formation of the foamable material, the composite preimpregnated material, and the metallic member. After removal from the mold, the holes of the semi-product crank is tapped, and the semi-product crank is then trimmed and ground. Patching is applied to make an outer surface of the crank smooth.

대표청구항 ▼

[ What is claimed is:] [1.] A method for manufacturing bicycle cranks, comprising the following steps of:(a) applying a layer of foamable material on an outer surface of a metallic member which has two holes respectively defined in two ends thereof;(b) applying a layer of composite preimpregnated ma

[ What is claimed is:] [1.] A method for manufacturing bicycle cranks, comprising the following steps of:(a) applying a layer of foamable material on an outer surface of a metallic member which has two holes respectively defined in two ends thereof;(b) applying a layer of composite preimpregnated material on the layer of foamable material;(c) mounting the metallic member of step (b) in a mold including an upper mold section and a lower mold section;(d) heating the mold to make the foamable material foam, thereby achieving formation of a semi-product crank by means of formation of the foamable material, the composite preimpregnated material, and the metallic member;(e) tapping the holes of the semi-product crank and trimming the semi-product crank; and(f) grinding and patching the semi-product crank to make an outer surface of the crank smooth.