Sports racquet with string port holes
View Patent ↗A sports racquet having a plurality of string port holes and conventional string holes is formed of a single tube of prepreg material. When molded, mold elements press opposed portions of the prepreg tube into contact with one another, and shape the adjoining prepreg material into a string port hole blanks. The portion of the pressed-together material which initially blocks the string port hole is removed after molding so that the string port holes extend through the frame. Alternatively, the mold elements cause the prepreg tube to follow a serpentine shape, thereby defining string port holes which are open alternately along the top and bottom surface of the frame. A pair of cover rings may be secured to the top and bottom racquet surfaces to cover the open sides of the string port holes.
1. A process for forming at least a portion of a frame for a sports implement, said process comprising the steps of:
(a) providing a prepreg tube having a hollow interior, said prepreg tube having a central axis and an axial location which includes opposed first and second wall portions and opposed third and fourth wall portions positioned between said opposed first and second wall portions, and wherein said wall portions include an outer surface;
(b) placing an inflatable bladder within said hollow interior;
(c) placing said prepreg tube inside a mold which, when closed, forms a mold cavity in the desired shape of said outer surface;
(d) placing in said mold cavity a mold member having a first surface which presses a first part of said first wall portion into contact with an opposed portion of said second wall portion, and a port-forming annular surface which extends from said first surface outwardly beyond the outer surface of non-pressed in portions of said first wall portion;
(e) pressurizing said bladder to inflate said prepreg tube so that a second pressed-in part of said first wall portion, which connects said first pressed-in part and said non-pressed in portions of said first wall portion, conforms to the shape of said port-forming surface and such that the non-pressed in portions of said first wall portion conform to the shape of the mold, thereby forming a string port hole blank having a sidewall; wherein at axial locations on either side of said string port hole blank, said inflated tube is hollow in cross-section, and wherein the sidewall of said port hole blank is spaced laterally from said third and fourth portions;
(f) heating said mold such that said prepreg tube cures to form a tubular frame wall having a thickness, and such that said pressed together portions are fused together; and
(g) removing the portions of said pressed-together portions which block said string port hole blank, thereby to form an open port hole which extends through the hollow interior of the racquet frame between opposed outer surfaces, while leaving portions of said pressed together portions lying outside of said string port hole to complete the sidewall of said string port hole.
2. A process according to claim 1 , wherein said sports implement is a sports racquet having a string bed plane, wherein a plurality of port holes are formed having an axis lying in the string bed plane to form string holes.
3. A process according to claim 2 , wherein said mold includes a head forming portion, a shaft forming portion, and a handle forming portion, and wherein a single prepreg tube is placed in said head, shaft, and handle forming portions.
4. A method according to claim 3 , wherein said mold cavity contains a plurality of mold members for forming a plurality of string port holes.
5. A process according to claim 1 , wherein said mold cavity contains a plurality of mold members for forming a plurality of port holes.