Plastic and nonmetallic article shaping or treating: processes – With step of making mold or mold shaping – per se – Utilizing surface to be reproduced as an impression pattern
Patent
1997-03-19
1999-03-09
Silbaugh, Jan H.
Plastic and nonmetallic article shaping or treating: processes
With step of making mold or mold shaping, per se
Utilizing surface to be reproduced as an impression pattern
264101, 264222, 264571, 264DIG30, 264DIG78, 425 2, B29C 3340
Patent
active
058796053
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method for forming soles and a device for implementing this method.
This method and this device are intended, in particular, for manufacturing corrective soles which can be used in podology or high-performance soles to be used when taking part in sports.
It is known to make the molding of a foot by means of an apparatus comprising at least one airtight flexible pouch containing a granular material such as polystyrene pellets, the pouch being connected to a vacuum pump enabling it to be placed under vacuum. For making the molding, the foot is firstly pressed on the pouch, the inner volume of which is then at atmospheric pressure, until it pushes into the granular material. The pouch is then placed under vacuum. It shrinks around the foot, drawing the granular material together, and preserves the molding thus obtained for as long as the vacuum is maintained.
A sole blank cut from a sheet of thermoplastic material is then heated by suitable means and is then placed in the bottom of the molding. The user again inserts his foot in the molding and presses on this blank to mold it by squashing it between the underside of his foot and the bottom of the molding. After cooling, the blank preserves the shape imparted to it by the foot and by the bottom of the molding and constitutes a sole to be placed in a shoe.
When it is desired to obtain a corrective sole, the usual procedure is to place, on the bottom of the molding, one or more corrective elements, of slightly domed shape, for creating a convex relief at the appropriate places of the sole blank. This or these elements are usually placed at the location of the metatarsal heads and are commonly called "metatarsal pads" or "retrocapital bars".
The convex reliefs thus obtained on the sole make it possible to relieve the metatarsal pressure and to reshape the natural arch of the front of the foot at the metatarsal heads, this arch tending to collapse when the foot is pressing down.
In practice, it is very difficult to position these metatarsal pads or retrocapital bars completely accurately. A fault in positioning gives rise to the metatarsal heads pressing against this relief of the sole, which can prove to be uncomfortable, painful in the long term, and even traumatizing.
A reduction in the dimensions of the pad for relieving this positioning inaccuracy leads to a reduction in the dimensions of the convex reliefs created on the sole and therefore the efficiency of the foot's support.
Furthermore, it is also very difficult accurately to determine the thickness to give to these metatarsal pads or retrocapital bars. This is because the flexibility of the foot at the metatarsal heads varies a great deal from one individual to another. An excessive height of the pad is uncomfortable and painful for the user, whereas an insufficient height sole.
The present invention aims to remedy this main drawback by providing a method which makes it possible to obtain a positioning and a shape, perfectly adapted to each user, of the convex reliefs of the sole for supporting the foot, as well as the inner and outer lateral plantar arches of the foot.
To this end, the method to which it relates comprises the steps of: on its underside and inner and outer lateral arches inward, i.e. toward the top of the leg; material for making a molding which is capable of flowing into the cavities which result from the compression of the foot and which is capable of filling these cavities; having been treated so as to be capable of being shaped by pressure from the foot on it; and shape it between the inner face of the foot and the bottom of the molding.
The foot actually comprises bony parts, such as the metatarsal heads, which are hard, and fatty or tissue parts, which are soft. These soft parts tend to collapse when the foot is pressing down, particularly at the location of the abovementioned metatarsal heads and lateral arches. It thus appears that many feet, at the location of these heads and of these arches, form a convex molding
REFERENCES:
patent: 2499324 (1950-02-01), Mead
patent: 3848287 (1974-11-01), Simonsen
patent: 3995002 (1976-11-01), Brown
patent: 4869001 (1989-09-01), Brown
Mason Suzanne E.
Silbaugh Jan H.
Societe D'Importation De Diffusion Ou Distribution D'Articles De
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