Method And Apparatus For Custom Molding Shoes And Boots

Abstract

A boot or shoe is formed of thermoplastic material. To better conform it to the wearer's foot, the wearer puts his foot within the boot and places it within a bag of a plastic material having a melting temperature higher than the molding temperature of the boot. A vacuum line is also placed within the bag and the top of the bag is sealed around the user's leg. Then the boot is heated to its softening temperature but below the melting point of the bag. A vacuum is then applied to the vacuum line to evacuate the air from within the bag to allow atmospheric pressure to exert a force on the bag and boot and to press it against the wearer's foot. While the vacuum is being maintained within the bag, the boot is cooled below its softening temperature so that the boot will permanently conform to the user's foot.

Description

BACKGROUND OF THE INVENTION

This invention relates generally to ski boots, shoes or other footwear wherein it is desirable to have the boot conform to the user's foot. The invention is generally related to the invention set forth in application Ser. No. 449,963, filed Mar. 11, 1974, to Anthony J. Kahmann, entitled Method of Custom Molding Footwear.

It has been recognized that it is desirable to have a boot or shoe which conforms to the user's foot when strains are being applied thereto. Foot strains occur during exercising and general athletics, but sports such as hiking, skating, football, and mountain climbing are known to provide more severe strains to the participant's foot. However, because of its fast speed and because the foot is constantly under strains from a variety of sources, skiing provides the greatest strain to an athlete's feet.

Even in ordinary footwear, there is a need for a shoe or boot which will better support the foot being of such a size that the user's foot will not slide or be held too tightly at any portion of the shoe. Unfortunately, there are only a limited number of different sizes of footwear corresponding to standard lengths and standard widths, and two people who have the same "size" foot do not necessarily have similarly shaped feet. With ordinary footwear, this difference is usually not crucial unless there is an abnormality in the foot. However, these small foot differences are magnified when forces during athletics are applied to the foot and shoe.

There have been numerous attempts to provide footwear that better conforms to the wearer's foot. In the field of ski boot manufacturing, these attempts have generally taken four directions.

The first method is to have a ski boot of soft material with adjustable buckles so that the tightness of the shoe can be modified. This is an older method and it is similar to that employed in ordinary footwear wherein the laces may be adjusted to make the boot or shoe more comfortable to the user. This method has drawbacks because the laces do not cover the entire foot but merely serve to tighten the boot about the instep. Also, the soft material, needed to assure that the boot can be laced tightly, may not provide sufficient support to the lower leg and ankle necessary for efficient skiing.

The second method of improving the fit of a boot is to provide an expandable material between the inside of the boot and the user's foot. In that system, the internal portion of the boot may be fitted with a bladder which can be filled with air to have the bladder apply pressure to the foot and prevent movement within the boot. Another method on the same principle is to have a moldable foamed plastic injected within the boot when the user's foot is therewithin, then allowing the material to expand, cool, and reach its hardened temperature. These methods are improvements over the buckle and lace methods of having the boot formed to the foot, however, these methods also have some drawbacks. The use of foam plastics requires that the user remain fairly stationary within the boot for upwards of one-half hour while the material cures. This is time consuming and uses up valuable time of sales personnel selling the boot. Also, the rather hot foamed plastic that is injected within the boot is uncomfortable to the user. Changes in the user's foot, for example from gaining weight, injury, or the like cannot be compensated for because the foam injection alters the boot permanently. The air bladder method has the drawback that the air cannot completely cushion the foot from the violent moves in skiing. Also, the air bladder is somewhat cumbersome to fill each time the boot is to be used.

A third method of improving the fit of a boot is to provide an inner boot, inside the outer shell, which holds a jelly like material which conforms to the wearer's foot when pressure is placed against it. This flow material is generally placed in the inner boot at the point of manufacture. The drawbacks of the flow system are that the flow is subject to compression after prolonged use which results in a poorer fit, and conformation of the flow to the wearer's foot causes variable thicknesses of flow material which separates the foot from the outer shell, further causing pressure points on the foot.

A fourth method has been proposed by Geller, in U.S. Pat. No. 3,613,271, dated Oct., 1971. The method concerns having a ski boot made from thermoplastic material which is moldable at a temperature between 120.degree. and 140.degree.F. The boot is placed on the wearer's foot and brought up to temperature. When it reaches the desired temperature, the user or other person pushes the sides of the boot against the foot with his hands. Instead of hands, a pressure cuff could also be used. This has certain advantages over the other systems. First, a conventional thermoplastic ski boot may be used which can be modified by this process. Secondly, the boot may be remolded at a later time to accommodate changes in the structure of user's foot. Thirdly, the skier does not have to take preliminary steps such as inflating the bladder prior to each use.

There are certain drawbacks to this system. By having a boot moldable at a temperature between 120.degree. and 140.degree.F, the boot could become soft in the trunk of a car thereby changing the boot's shape. The use of hands to compress the boot about the foot causes uneven pressure application and can result in having a boot too tight in certain places and too loose in others. A pressure cuff does not alter this condition because its application of forces is also uneven.

As taught in the aforementioned application to Kahmann, a vacuum is applied to the inside of a boot and the resultant ambient pressure acting on the outside of the boot causes it to be drawn inwardly toward the foot. Although the method is effective in fitting the boot, it has been found that there is a tendency for air to leak from the outside into the boot to lower the amount of vacuum (i.e., increase the pressure) within the boot. The invention herein prevents loss of vacuum so that the system is more effective and efficient.

It is therefore an object of this invention to provide a boot or shoe which will not have the drawbacks of prior art footwear. Primarily, it is an object of this invention to provide a system to conform a boot to the user's foot to fit the user's foot evenly and tightly over all parts of the foot. Also, an objective of the invention is to provide a boot that will not melt or soften at temperatures likely to be reached in normal use. A further object is to correct the shaft of the boot, the angle which the leg makes with the foot. A further object of the invention is to provide a system whereby the foot is protected from hot material to thereby ease discomfort.

BRIEF DESCRIPTION OF THE INVENTION

These objects are accomplished by having a system for providing support for the foot which includes boot means formed with a shell of moldable material. An essentially air tight bag means is placed around the shell to seal the boot means. Thereafter, vacuum means acting inside the bag means cause the bag to create a lower than ambient pressure within the bag means to exert a force on the shell. Heating means cause the shell means to reach a moldable temperature whereby the vacuum acts on the shell when the shell is at the moldable temperature to cause the boot to form to the foot. Then cooling means are applied to the boot while the vacuum is being maintained until the boot drops below the molding temperature. The user's foot may be withdrawn from the boot and a boot of perfect fit is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side view of the boot inserted within a plastic bag.

FIG. 2 shows the bag being sealed around the user's leg with the boot within the bag.

FIG. 3 shows the sealed bag with the vacuum having veen applied so that the bag is compressed around the boot.

FIG. 4 is a sectional view through section IV--IV of FIG. 3 of the boot.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Boot means are formed with a shell of moldable material. In the preferred embodiment, such boot means 10 is formed of a shell 17 formed of a thermoplastic material which is rigid at room temperature and becomes moldable with memory between 180.degree.F and 380.degree.F, preferably about 350.degree.F. At that temperature, a compromise is reached between the highest temperatures to which the foot can be subjected and temperatures to which the boot might ordinarily be subjected in a heated automobile trunk or near a fireplace or wall heater. The shell is lined with neoprene rubber at 16 also of a consistent thickness for insulation from heat and cold and for evenly cushioning the foot from the hard plastic material. The boot also comprises a sole 11 made to conform to a ski binding, an ankle portion 12, and an instep portion 13. Additionally, a buckle 14 allows the instep portion 13 to be moved to allow insertion and removal of the foot.

Essentially, the major difference between the Kahmann application and the invention herein, is the use of air tight sealing means for placement around the shell which seals the boot means. In the exemplary embodiment, such sealing means 20 comprises a bag made of a film of polyethylene terephthalete, such as sold under the trademark Mylar, or of other plastic materials, metallic material, rubber, or any combination of these materials. The chosen material should be flexible so that it will conform to the boot, being a thin film so that it will not insulate the boot from applied heating and cooling, and must have a melting point higher than the molding temperature than that of the shell of the boot. Mylar is the preferable material because it has a sharp melting point above 400.degree.F, or about 50.degree.F higher than the boot's softening point. Mylar bags are available and because they are transparent, the boot may be inspected visually while it is within the bag. After the boot is placed on the foot, the boot is placed within the bag and the bag is sealed by appropriate means. In the preferred embodiment, such means includes an elastic band 23 placed around the top of the bag 22 and around the user's leg 1. The elastic band 23 is made tight enough so that no air can pass between the top of the bag 22 and the leg 1.

Vacuum means lowers the pressure within the sealing means below ambient pressure so that atmosphere pressure exerts a resulting froce on the outside of the sealing means to apply external pressure to the shell. In the exemplary embodiment such vacuum means 50 includes a tube 51 connected to a source of vacuum (not shown) nearby. The vacuum line 51 is placed within the bag adjacent the boot shell preferably near the buckle. In the position shown in FIG. 1, a pad of soft material 15 is placed over the buckle near the end of the tubing. This flexing material serves to protect the bag 21 from the sharp buckle 14.

Referring now to FIG. 2, the elastic band 23 has been placed around the leg to make an air tight seal around the boot.

In FIG. 3, the vacuum means 50 has applied a vacuum through the vacuum tube 51 to draw the bag tightly around the shell of the boot. Heating means heats the shell means to a moldable temperature whereby the vacuum acts on the shell to cause the boot to conform to the foot. In the exemplary embodiment, such heating means comprises a heater source 30. The heater source could be many different heating means. We have found that an industrial hand-held blower with an electrical resistance heating element is a preferred source of heat. These heating blowers are capable of directing hot air at a specific location by holding the output end of the blower near that location, or they can heat a general area by holding the output end farther away from the material to be heated. This feature allows flexibility in the use of this invention. Such heating blowers are capable of temperatures high enough to heat the shell to its softening point, about 350.degree.F. It is also possible with this type of blower to direct the heat away from the uncovered portion of the user's leg.

Another heat source which may be used is a miniature electric blanket. Preferably, the heating elements are within a heat resistant and electrically insulated material. The blanket has the same area as the area of the largest boot sold, and is designed and shaped to fit on a boot with minimum folding. Alternatively, more than one blanket, each of a particular shape to heat a particular section of the boot could be used.

The blanket has certain advantages. For example, heat is more evenly applied to the boot and there is less use of energy than with a blower. The blanket system also might be quieter than a blower which may be important to a retail store where excess noise might irritate customers. If multiple blankets are used, heating of particular sections may be accomplished if desired. Other known heat sources could also be used but it is advantageous that they be portable and may be applied without moving the boot.

As the shell reaches its softening point, the atmospheric pressure will exert forces on the shell to cause it to move inwardly to conform to the user's foot. If the boot is too tight when bought, the force exerted by the user's foot against the boot will cause it to expand slightly to evenly conform to his foot. It has been possible to develop very high vacuum within such an arrangement and the atmospheric pressure can act very quickly on the shell. Therefore, it is unnecessary to maintain the boot at an elevated temperature for a long period of time. There is no discomfort to the wearer because his foot is protected by the neoprene liner 16 and optionally by a sock 2.

While the pressure is maintained on the shell, the shell cools below its molding temperature. This cooling may be accelerated by applying a cooling means to the boot while the vacuum is maintained at least until the temperature of the boot drops below the softening temperature. In the exemplary embodiment, such cooling means includes a cooling source 40. Preferably, this cooling source is an aerosol coolant which can be sprayed directly on the outside of the bag. This method will cool the boot very rapidly. Of course, a water bath could also be used but it is desirable that the foot not be moved during the process so that the boot will conform to the user's foot when it is in its supporting position. It is advisable to maintain the vacuum at least until the boot drops below the molding temperature so that forces exerted by the foot outside against the inside of the shell will not cause any non-conforming regions within the boot.

Shaft of a ski boot is defined as the angle which the ankle portion of the boot 12 makes with the rest of the boot. It should conform to the angle which the leg makes to the foot. The concept of "shaft" can be illustrated by picturing a set of regular leather boots which have been worn for some time. If they are placed on a flat surface, a slight bend should be evident about the ankle, and the boot should naturally maintain this angle or shaft. The present device assures a correct shaft because the user should be standing naturally on a flat surface and as heat is applied to the top portion of the boot, it will bend slightly to assume the correct shaft.

It should also be noted that by allowing outside air to be the source of pressure to the shell, the heating and cooling means can be applied to the boot while the boot is undergoing pressure deformation. This is important because the boot would have to be heated to a higher initial temperature so that the pressure applying means could be placed around the boot as the boot cooled to its minimum molding temperature. Also, the pressure applying means would have to be removed from the boot if cooling means were applied to the boot and without such pressure, the boot could deform during cooling. Without the use of cooling means so that the pressure could be maintained, the warm boot would stay on the user's foot a longer period of time, and if the pressure means is still around the boot, it inhibits ambient air from reaching the boot to cool the shell.

Because the boot may be heated and cooled quickly, boots of a material of higher softening temperature may be used. This guards against accidental deformation of the boot from the heat of a fireplace or in an automobile trunk. Also, the neoprene lining protects the foot during the short heating period.

If for any reason the shape of the user's foot changed, the process could be repeated quickly. If the user decided to sell his boots, his custom formed boots could be modified to become the buyer's custom boots if their feet are of similar "size."

Thus, we have shown an improved system for conforming a shoe or boot to a foot including boot means 10 of a material which is moldable at a certain temperature. Heating means 30 heats the boot to the temperature. Pressure applying means molds the boot to the foot. The improvement includes the provision of having a vacuum means 50 applying a vacuum from within the boot to cause the boot to collapse around the foot. In order to improve the vacuum application, a sealing means 20 in the form of an air tight bag 21 sealed tightly around the user's leg is placed around the boot and a vacuum tube 51 placed therewithin to evacuate air within the bag so that atmospheric pressure exerts resulting forces on the outside of the sealing means to apply external pressure on the shell.

Claims

I claim:

1. A method of forming a boot or shoe of moldable material to better conform it to a user's foot after having placed the boot on the user's foot including the steps of:

a. surrounding the boot with a flexible, air tight material with a melting temperature higher than that of the molding temperature of the boot;

b. making an air tight seal between the flexible, air tight material and the boot;

c. applying a vacuum beneath said flexible air tight materials;

d. applying sufficient heat to the boot for the boot material to become moldable while maintaining the vacuum so that the vacuum will cause the boot to mold toward the foot to conform thereto.

2. The method of claim 1 further including the step of applying cooling means to the boot at least until the boot material drops below the molding temperature while maintaining the vacuum.

3. In a system for providing better support for a foot;

boot means formed of a shell of moldable material;

essentially air tight sealing means for placement around said shell to seal the boot means;

vacuum means for acting inside said sealing means for lowering the pressure within said sealing means below ambient pressure so that atmospheric pressure exerts a resulting force on the outside of the sealing means to apply external pressure to the shell;

heating means for heating said shell to a moldable temperature whereby the vacuum acts on said shell when said shell is at a moldable temperature to cause said boot to conform to the foot.

4. The system of claim 3 further including cooling means for cooling said boot at least below the molding temperature while the vacuum is maintained at least until the boot drops below the molding temperature.

5. In an improved system for conforming a shoe or boot to a foot including:

boot means of material which is moldable at a certain temperature;

heating means to heat said boot to said temperature; and

pressure applying means to mold the boot to the foot, the improvement including the provision of having;

a. said pressure means includes means to apply a vacuum from within said boot to cause said boot to collapse around the foot

b. sealing means placeable around said boot to seal said boot from the atmosphere whereby said vacuum acts within said sealing means to provide a lowered pressure within said sealing means so that atmospheric pressure exerts resulting forces on the outside of the sealing means to apply external pressure to the boot.

6. The improved system of claim 5, further including the provision of having cooling means acting on the boot while the vacuum is maintained to cool the boot below the molding temperature.