A flexible polyvinyl chloride foam member is provided with a permanent profile or shape by use of compressive pressure and radio frequency heating. The resulting article has a higher concentration of smaller foam cells in a portion of higher density than in a portion of lower density.
The present application is a division of my U.S. Pat. application Ser. No. 851,796 filed Aug. 21, 1969 now U. S. Pat. No. 3,591,882 issued July 13, 1971.
This invention relates to a supporting insole built into a shoe or other article of footwear, and to the article of footwear containing said insole, the insole being shaped to conform to the plantar surface of a human foot and seated in a recess in the outsole to which the insole and upper are attached.
A shoe which includes a metatarsal arch support comprising a heel portion; a medial portion extending from the heel portion; and a metatarsal portion extending from the medial portion and terminating in a round metatarsal edge; which support increases in width from the medial portion to the metatarsal edge; the medial portion having a curved transverse cross-sectional shape; and the metatarsal portion having a crescent transverse cross-sectional shape which flattens by way of a wedge-shape into the round metatarsal edge; the metatarsal edge being adapted to be substantially below the joints of the five metatarsal bones to the proximal phalanges.
A sheet material which yields under non-uniform pressures caused by irregularities of contact between two relatively hard surfaces adapted to provide a more uniform pressure distribution comprising the combination of relatively small granules and relatively small stiff fibers in a matrix of waxy material adhered to a cover sheet of flexible material.
An EVA insole manufacturing process includes a step of making a molding by injecting molding an EVA resin and foaming agent mixture without through crushing or cutting procedure, and a step of heating the molding thus obtained in a mold so that it forms into a predetermined shape. Two or more moldings which respectively contain a different concentration of foaming agent or a different pigment color may be molded together so as to produce an insole which has different hardness and color at different parts thereof.
Improved footwear for physical exercise, such as running or jogging, in which a segment of the shoe extending beneath the third, fourth and fifth metatarsal-phalangeal joints on the lateral side of the shoe is comprised of a crepe or spongy rubber material, which is substantially more flexible than the material which comprises the remainder of the solepiece. This configuration reduces the resistance of the solepieces to the flexure of the foot along the third, fourth and fifth metatarsal-phalangeal joints, thereby reducing the stress on the corresponding foot muscles and allowing the stronger foot muscles which operate the first and second metatarsal-phalangeal joints on the medial side of the foot to do most of the work in flexing the foot during the running motion. As a result, the weaker muscles in the lateral side of the foot are not overly stressed and the direction of motion of the foot at the toe lift-off is substantially in the desired direction of running. In another aspect of the invention, an orthodic piece which is custom fit to the individual runner is provided to counteract foot problems, such as, for example, over-pronation, supination and high arch. The orthodic piece may be disposed inside the shoe or, alternatively, may be disposed between the bottom of the upper portion of the shoe and the midsole.
