Method of molding piston cups

Claim 1

A METHOD OF MAKING PISTON CUPS HAVING A HARD CIRCULAR PISTON-ENGAGING BOTTOM AND AN ANNULAR CYLINDER-ENGAGING LIP WHICH IS INTEGRAL WITH AND SIGNIFICANTLY SOFTER THAN SAID BOTTOM, SAID METHOD COMPRISING: (A) FORMING A BOTTOM PORTION OF THE CUP IN A SHAPE OF A DISC FROM A FIRST MOLDABLE VULCANIZABLE RUBBER COMPOUND WHICH WHEN UNCURED IS DEFORMABLE BUT WHEN CURED IS SIGNIFICANTLY HARDER THAN THE LIP POR: TION OF THE CUP; (B) ENCLOSING SAID DISC WHILE IN ITS UNVULCANIZED STATE IN A MULTI-PART SPRUE-LOADING PISTON CUP MOLDING CAVITY WITH SAID DISC ON THE BOTTOM MOLDING SURFACE OF SAID CAVITY AND OCCUPYING ONLY A PART OF THE TOTAL VOLUME OF THE CAVITY; (C) INJECTING INTO THE CAVITY A SECOND MOLDABLE VULCANIZABLE RUBBER COMPOUND TO FORM THE LIP OF SAID PISTON CUP, WHICH SECOND COMPOUND WHEN CURED IS SIGNIFICANTLY SOFTER THAN SAID FIRST COMPOUND; (D) DIRECTING SAID SECOND COMPOUND AS IT IS SO INJECTED SO THAT IT ENTERS SAID CAVITY ONLY AT A SERIES OF ARCUATELY SPACED LOCATIONS CLOSE TO THE PERIPHERY OF SAID DISC AND INITALLY ENGAGES ONLY THE PERIPHERY OF THE DISC TO PRESS THE DISC AXIALLY AGAINST THE BOTTOM OF THE CAVITY; (E) CONTINUING THE INJECTION OF SAID SECOND COMPOUND AT SAID LOCATIONS AND IN SAID DIRECTION UNTIL SAID SECOND COMPOUND COVERS SAID DISC AND FILLS ALL AVAILABLE SPACE IN SAID CAVITY NOT OCCUPIED BY SAID DISC; (F) THEN VULCANIZING SAID COMPOUNDS IN SAID CAVITY.

Claim 2

A METHOD OF MAKING PISTON CUPS HAVING A HARD CIRCULAR PISTON-ENGAGING BOTTOM AND AN ANNULAR CYLINDER-ENGAGING LIP WHICH IS INTEGRAL WITH AND SIGNIFICANTLY SOFTER THAN SAID BOTTOM, SAID METHOD COMPRISING: (A) FORMING A BOTTOM PORTION OF THE CUP IN A SHAPE OF A DISC FROM A FIRST MOLDABLE VULCANIZABLE RUBBER COMPOUND WHICH WHEN UNCURED IS DEFORMABLE BUT WHEN CURED IS SIGNIFICANTLY HARDER THAN THE LIP POR: TION OF THE CUP; (B) ENCLOSING SAID DISC WHILE IN ITS UNVULCANIZED STATE IN A MULTI-PART SPRUE-LOADING PISTON CUP MOLDING CAVITY WITH SAID DISC ON THE BOTTOM MOLDING SURFACE OF SAID CAVITY AND OCCUPYING ONLY A PART OF THE TOTAL VOLUME OF THE CAVITY; (C) INJECTING INTO THE CAVITY A SECOND MOLDABLE VULCANIZABLE RUBBER COMPOUND TO FORM THE LIP OF SAID PISTON CUP, WHICH SECOND COMPOUND WHEN CURED IS SIGNIFICANTLY SOFTER THAN SAID FIRST COMPOUND; (D) DIRECTING SAID SECOND COMPOUND AS IT IS SO INJECTED SO THAT IT ENTERS SAID CAVITY ONLY AT A SERIES OF ARCUATELY SPACED LOCATIONS CLOSE TO THE PERIPHERY OF SAID DISC AND INITALLY ENGAGES ONLY THE PERIPHERY OF THE DISC TO PRESS THE DISC AXIALLY AGAINST THE BOTTOM OF THE CAVITY; (E) CONTINUING THE INJECTION OF SAID SECOND COMPOUND AT SAID LOCATIONS AND IN SAID DIRECTION UNTIL SAID SECOND COMPOUND COVERS SAID DISC AND FILLS ALL AVAILABLE SPACE IN SAID CAVITY NOT OCCUPIED BY SAID DISC; (F) THEN VULCANIZING SAID COMPOUNDS IN SAID CAVITY.