Shoe Molded By Induction Heating

Abstract

The invention concerns a shoe whose bottom has a layer of thermoplastic material in it and which has embodied in its bottom electromagnetic energy absorbing material which can be heated by alternating magnetic flux, thus activating the layer of thermoplastic material which then can be molded according to the contour of a human foot.

Description

BACKGROUND OF THE INVENTION

This invention relates to footwear of any kind, as boots, sandals, shoes, etc. . . However, henceforth the word shoe will be used only. Human feet vary in length, width and contour. There is even a difference between the left and the right foot of the same person, due to gait and walking habits. In a shoe factory, the shoes are made over lasts which are to represent human feet. These lasts take into consideration the various lengths and widths, but as to the contour of a foot, they are a compromise only.

In the past, when shoes were handmade and leather was the only material used, they could be fitted to the overall contour of each individual foot. Moreover, a leather shoe has the outstanding feature of gradually shaping itself to the contour of a human foot. The advantages of handmade leather shoes have been lost to a great extent in present-day mass production. In particular, leather is replaced by synthetic material which does not possess the feature of shaping itself to the contour of a human foot. For this reason, it is hard to break in new shoes made of synthetic material.

SUMMARY OF THE INVENTION

It is the main objective of this invention to provide a finished shoe whose bottom can be quickly molded according to the bottom contour of a human foot at any time after the shoe has left the factory. This does not only eliminate the long break-in time and the disadvantages of mass-produced shoes, but also can be of particular importance for people who have crippled or abnormal feet.

Shoes, according to the invention, have a layer of thermoplastic material which in many cases will be the insole. In the bottom of the shoe, close to the layer of thermoplastic material, is embodied electromagnetic energy absorbing material such as small parts of steel, aluminum, copper, graphite, etc. . . These parts can be heated by exposure to an alternating magnetic flux. This method of heating is known as induction heating. Induction heating machines are commercially available, and they will be referred to in conjunction with this invention only. When the thermoplastic material is activated, and a person lets the weight of his body rest on the bottom of the shoe, the imprint of the foot will be in the shoe in less than a minute.

DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example, with reference to the drawings.

FIG. 1 is a perspective view of a shoe with a transverse section through the forepart area.

FIG. 2 is a transverse section of a shoe showing the insole contoured according to the toes of a foot.

FIG. 3 is a perspective view of a shoe with a foot in it and a cutaway view of the bottom area. The shoe is resting on coils of an induction heating machine.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 1 is shown a cement-lasted shoe. However, it should be understood that this invention is applicable to any kind of shoe construction. The insole 8 is made of thermoplastic material, for instance thermoplastic foam made of polyethylene, polypropylene, polyvinyl cloride, etc. . . Adjacent to the insole 8 are located electromagnetic energy absorbing discs 4 which are shown somewhat enlarged for the sake of illustration. The electromagnetic energy absorbing discs can be made of any conducting material such as steel, copper, aluminum, graphite, etc. . . Also, the shape of the material 4 is functionally unimportant. Furthermore, the location of the electromagnetic energy absorbing material 4 in the bottom of the shoe might vary with each type of shoe. For instance, it could very well be part of the filler material 6. In some cases it might be attached to the outsole 6. The upper 10 and its lining 12 are made of a material which can withstand the activation temperature of the thermoplastic insole 8.

In FIG. 2 is shown a thermoplastic insole 8 which has been activated and molded according to the contours of the toes of the foot F.

In FIG. 3, the foot F with shoe rests on the coils 14 of an induction heating machine. In this illustration, the thermoplastic insole 8 is shown prior to activation and molding. Shoes which have been made with electromagnetic energy absorbing material 4 located in an appropriate bottom area according to the construction of the shoe, are shipped to a retail store as usual.

A retail store has to be equipped with an induction heating machine (not shown in the drawing). After a customer has selected a pair of shoes she puts them on and stands on the coils 14 of an induction heating machine. When the induction heating machine is turned on, an alternating electromagnetic field surrounds the coils 14 and transfers part of its energy to the electromagnetic energy absorbing material 4. In the material 4 the electromagnetic energy is changed into heat. Then, this heat activates the thermoplastic insole 8 or a similar layer of plastic material in the bottom of the shoe. Under the weight of the body, the activated thermoplastic insole 8 will mold according to the contour of the bottom of the customer's foot. Of course, the activation temperature of the thermoplastic material is such that the foot does not suffer from burns. Also, the frequencies of an induction heating machine are not in any way dangerous to human health.

The construction of the shoe, the kind of thermoplastic material, and the shape and kind of electromagnetic energy absorbing material will necessitate various embodiments without departing from the character of the invention.

Claims

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A shoe of any make having located in its bottom area electromagnetic energy absorbing particles and a layer of moldable material which can be heat activated by said electromagnetic energy absorbing particles when the shoe is exposed to the alternating electromagnetic field of an induction heating machine.

2. A shoe of any make according to claim 1 in which the electromagnetic energy absorbing particles and the layer of moldable material are integral parts of factory-finished shoes.

3. A shoe of any make according to claim 1 in which the layer of moldable material can be softened to such a degree as to receive the imprint of a human foot.

4. A shoe of any make according to claim 1 in which the layer of moldable material consists of one or several thin sheets of plastic material.

5. A shoe of any make according to claim 1 in which the electromagnetic energy absorbing particles consist of electrically conductive material which is arranged in the shoe bottom in such a manner as to uniformly heat activate the layer of moldable material when the shoe bottom is to receive the imprint of a human foot.

6. A shoe of any make according to claim 1 in which the electromagnetic energy absorbing particles and the layer of moldable material are combined with the shoe insole.

7. A shoe of any make according to claim 1 in which the electromagnetic energy absorbing particles and the layer of moldable material are already combined with the sheet out of which the shoe soles are to be cut.

8. A shoe of any make according to claim 1 in which the layer of moldable material consists of plastic foam.