US2742657A - Molded shoe insert - Google Patents

Description

April 24, 1956 s o 2,742,657

MOLDED SHOE INSERT Filed Feb. ll, 1955 2 Sheets-Sheet l INVENTOR. Roam; 6. .52 041v:

BYWW

ATTORNEYS.

April 24, 1956 SLOANE 2,742,657

MOLDED SHOE INSERT Filed Feb. 11, 1955 v 2 Sheets-Sheet 2 INVENTOR. Aoamr 15 6A 0A NE ATTORNEYS.

United States Patent MOLDED SHOE INSERT Robert B. Sloane, Rye, N. Y.

Application February 11, 1955, Serial No. 487,595

Claims. (Cl. 12---146) The present invention relates generally to foot-supporting inserts for shoes, and more particularly to an inner sole pre-molded to conform to the plantar of a wearers foot and insertable in a shoe of standard design, and to techniques for forming such individualized inner soles.

Ready-to-wear shoes manufactured on a mass production basis are not designed to conform to an individual foot but are constructed about an idealized last having no human, counterpart. The fact that the plantar area of a given human foot has a depth of curvature and a contour which is characteristic. solely of that foot and corresponds to no other foot is necessarily disregarded in dimensioning the mass-produced shoe. The range of variation in human foot shapes is so great that conventional width and length sizes can at best only approximate the needs of the in-' dividual wearer.

Many foot ditficulties arise from the prolonged use of shoes which are ill-fittingi and fail to provide adequate support. The limitations of the standardized shoe are well recognized and various expedients have heretofore been proposed to afford. proper support for the arch as well asother areas of the foot. For example, it" has been proposed to-form casts which correspoudto the foot of.

the wearer and to construct or mold a shoe about the cast. Such individualized shoes are very costly and entail acomplicated and time-consuming production technique; Moreover, the resultant shoe-has-a somewhat crude and awkward appearance which compares unfavorably with the highly finished, mass-produced: product; For a pro spective purchaser, the orthopedic virtues of such individ ualiz'ed shoes are usually outbalan'ced by their aesthetic drawbacks.

Attempts have also been made to fit standard shoes with replaceable supports for: the feet, such as heel cushions and. metatarsal supports. However, as a practicalmatter, such shoe inserts cannot be manufact'urediin atsufficient variety of shapes and sizes to make -availablesup ports adapted to fit any individual foot. Difficulty isalso experienced in maintaining the proper position of sucharch supports in the shoes. Shoe inserts ha-v'e beenapr-o- I posed which initially are formedof a s'oftmaterial and,

afterregistering the impression of the sole, are" setto formv a rigid body, The inflexibility of such insertsv render them impractical for use in shoes which; fiexinnonnal walkingmotion;

In. view of the: foregtiing;z it is the. principalaobject of the present invention to. provide a technique-whereby conventional shoes made on standard lasts can-bedndividua'lized for greater foot support and comfort;

More specifically, itis an object of the invention to provide an insert for a conventional shoe}. which= insert actsutoindividualize the shoe to the needso'f' the wearer, without in any way altering. the outer appearance of the shoe.

Another object of theinvention is to: providea shoe insert-which. is initially plastie and is moldedina forrner bycontact; with the foot offthe wearer suchthat' when the individualized insert is cured it will permanently retain the curing thereof is accompanied without shrinkage or warping; hence the finished i'ns'ert permanently maintains an accurate impression of the plantar of the foot. The fabrication of the insert may be carried out in such fashion as to add only slightlyto the time generally needed for purchasing new shoes.

A significant feature 'of the invention is'that the insert is usable with a standardized shoe and involves no changes in current machine methods of shoe manufacture. While the insert is impressed in depth to correspond to the plantar area of the wearers foot, the outline of the insert is made to correspond to that of the inner sole of a standardized shoe representing the personal selection of the wearer. Thus, the insert when fitted into the shoe lies snugly therein and cannot be displaced by foot movement. Moreover, the insert can be made inexpensively and does not add materially tothe purchase cost of the standard shoe. With the inserts in place the wearer will enjoyex; ceptional ease, whether standing or walking, in standard shoes which have been individualized for his comfort-.1

For a better understanding of the invention as well as other objects and further features thereof, reference is had to the following detailed description to be read in conjunction with the accompanying-drawing.

In the drawing: A Fig. 1 is a perspective view of a forrrlier for rnolding a plastic blanl insert to the shape of the plantar of the foot. Fig. 2 is a perspective view of a blank' insert. H N Fig. 3 shows a foot strapped in place in the former to form an impressidn tame insert.

Fig. 4 is a perspective view (if the top surface 6f the mdlddinsert. a A Fig. 5 is a perspective view of the bottom surface of ther'noldefd insert. I g k p I 6'isf a sectional view of as'taridard shoe having an individualized in en fitted th'er Iii i'nd'ividfializ'iug a machine-made shoe to riie't personal. needs of a prospective wearer, a stat dar d slide i s fi'rstf selectedfror'ri stocl t bytlie wearer in their 1 wa That is, under theg'uidance o aslioes'al'esmamtlie foot is measured and thew alter" nin' chooses a spa shoe representing h'i's' ersbn 'r prefei-efi'c'e' frofri the standpoint and em; which fits his tootmo'st eqmfb'r The selection of are standard shoe Having ene as; the technique is individualiz'e' the slio'' in s the 1 lowing procedure. The first" step is to ake use of slipper-like container or former; generally d' gna'te'd numeral 10 in Fig. 1', which former is appropri e' as the will be in size 9 4,71) width; The reason for: e din'er ence between foot: measurement and thefsites size. is" that when the melded s'ert i s fin'ally" placed in th slide; the foot of the w r w1ll be" e evated sllg of theslioe-is ndrm'auy eurte'd iawsr iy'and reads so what rs constrict' the f at wiles-1 elevate, of an oversize'sho'e 1 continents warren inse'rtp'rodi a slide. whicli fit's eonatenamy; A shoe s toi'' equipped to in'dividualize shoes will therefor' ha e available for this: purposeappropriate formers for are s'lios t6 b'e fitted with individualized inner soles.

The-:form'er 10 is'tabricated-of a rigid;ar'elativlytliin and light-weight material, such as aluminum, Mycalex (glass-bonded mica) or any other inexpensive material of proper rigidity and strength capable of maintaining its form when subjected to the heating involved in the curing process, to be later described.

The former is provided witha vertical contour wall 12 curved to surround the foot, and with two. removable straps 13 and 14 for holding the former to the foot of the wearer in walking movement. The former may also be made of sole and heel sections in hinged relation to provide an articulated device.

Strap 13 is relatively broad to cover the vamp and is provided at its free end with snap buttons 15, which are insertable in sockets 16 on wall 12 of the former. Strap 14 is an instep strap and is also provided with snap buttons 17 which are receivable in sockets 18 set in the contour wall.

Placed on the bottom of the former 10 is an impressionable insert blank 19, shown separately in Fig. 2, which is contoured to fit neatly into the former. The

blank 19 is of uniforinthickness, except in the region of the arch where it is made somewhat thicker. In practice, an insert uniformly of an inch thick, save in the arch area where it grades up to A; of an inch at the border, has been found satisfactory for this purpose.

The blank 19 is formed of a soft clay-like material whose properties are such that after having registered the impression of the plantar of the foot it may be processed or cured to take on a flexible, resilient form which resists permanent deformation. Preferably the insert blank is formed of plastigel compound whose physical properties are ideally suited for the purpose intended. Plastigel has an indefinite shelf-life in its uncured state and has a putty-like consistency and therefore may readily be molded to the undersurface of the foot. When heat cured, plastigel does not undergo appreciable dimensional change and in its cured form it is resilient, flexible and maintains the imprint introduced during its molding.

A plastigel is a dispersion of high molecular weight polyvinyl chloride resins, fillers, pigments and stabilizers in a liquid plasticizer medium. cizers is maintained in such concentration as to impart a modeling clay consistency to the material, the plasticizers being so chosen that their solvating effect at temperatures is at a minimum, hence the desired consistency is maintained.

Uncured, the plastigel compound has the soft puttylike consistency of modeling clay. Upon heating the compound to its fusing temperature, the plasticizers therein gain sufficient solvency and the resins are softened adequately, whereby solution occurs and the resin particles are fused together by the plasticizer. No curing of resins occurs; the phenomenon is one of simply increasing the temperature until the resin particles fuse together. It is therefore necessary merely to bring the entire mass to its fusing temperature. Extended bakes contribute nothing to the final product other than to accelerate the decomposition of the resin.

The fused product has the physical and chemical characteristics of vinyl compound and has excellent resistance to acids, alkalies, water and fungi. The latter characteristic is particularly important in a shoe with respect to fungus diseases of the foot.

A former and an insert blank, as above described, are provided for each foot, the feet of the wearer being strapped to the former, as shown in Fig. 3, to hold them in place as the wearer walks. In walking the weight of the wearers body causes the soles of the feet to form an impression in the blanks, thereby molding the putty-like plastigel snugly to the soles. in practice, the actual molding takes no more than three or four minutes of walking. It is to be understood that the impression is not in static form, but registers the dynamic contours of the plantar area.

The inner surface of the contour wall 12 of the former The quantity of plastiis provided, as shown in Fig. l, with a continuous bead line 20, which line indicates the limit of the important part of the insert. After curing, the insert is trimmed to this line.

After the blanks have been properly molded, the straps 13 and 14 are unsnapped, the feet are removed from the formers and the formers containing the molded inserts are then subjected to heat to cure the plastigel. This may be accomplished in a pro-heated circulating hot-air type of even and can be carried out in about 20 to 25 minutes at about 375 F. The curing time can be shortened by raising the temperature without adversely aficcting the qualities of the cured plastigel.

If preferred, an infra-red heater may be used to cure the plastigel or high-frequency dielectric heating may be used for this purpose to appreciably reduce the curing time. After heat curing the inserts, the formers containing the inserts are cooled rapidly. This may be accomplished, for example, by immersing the formers in a water bath.

The inserts in the formers are then trimmed to the bead line 20 to cut away the excessive portions along the edges of the inserts. The excessively contoured ridges between the toes are also trimmed. The inserts when removed from the formers will have the appearance shown in Fig. 4, where it will be seen that the top face of the insert has toe impressions 19a therein, as well as various curvatures in accordance with the curvatures of the plantar area of the foot. As shown in Fig. 5, the bottom face of the insert is the same as the inner sole of the shoe.

The inserts are now placed snugly in the selected standard shoes, and, as shown in Fig. 6, each insert is interposed between the sole of the foot and the inner sole of the shoe to provide proper foot support for the wearer. The shoe insert may, if desired, be covered in a soft suede-like leather 21 and then cemented into the shoe to become a fixed part thereof.

In the above-described method, the sole insert blank is shaped to conform to the plantar area of the foot by the use of a former, the molded insert thereafter being cured while positioned in the former. It is also possible to mold the blank without the use of a former. This may be accomplished by means of an uncured plastigel blank, of the type shown in Fig. 2, the blank being contained within a pliable semi-elastic envelope formed of a suitable plastic film. The foot-bearing surface of the envelope preferably is provided with a thin top layer of synthetic leather or a leatherette type of material. This top layer affords a smoother bearing surface for the foot by preventing an excessive amount of plastigel from intruding between the toes during molding.

The uncured insert blanks contained within the envelopes are introduced directly into the selected shoes, rather than being placed in formers. The wearer puts on the shoes with the blanks therein and deforms or molds the inserts by walking with the shoes for a few minutes. The shoes are then removed from the feet of the wearer and are placed in a dielectric heater for a short period sufficient to accomplish curing of the inserts without in any way affecting the leather of the shoes. This is made possible by the dielectric properties of the plastigel as compared to that of the shoe leather. The cured inserts are then allowed to cool naturally or by forced air draft. This procedure does away with the intermediate steps involving the use of formers and the transfer of the cured insert to the shoe.

An alternative method which obviates the need for curing by the use of heating apparatus makes use of an uncured plastic insert packaged within an envelope, as above described, the envelope incorporating a catalyst within a compartment separated from the uncured plastic. This compartment is formed by a thin breakable membrane disposed within the envelope to isolate the catalyst from the plastic. The weight of the foot on the packaged insert serves to rupture the separating membrane and thereby set 05 the curing cycle. The catalyst serves to initiate a reaction which will change the insert plastic from its uncured state to the cured state.

The characteristics of the plastic material in its uncured state should be such that by virtue of appropriate fillers the material is readily moldable, it has a reasonably long shelf life when properly packaged and will set upon the application of a non-toxic plasticizer or catalyst, the setting takes place concurrently with the molding. The material, when cured, will maintain indefinitely the deformation introduced by molding, and be semi-resilient and sufiiciently flexible to bend approximately 35 without tearing.

Among the substances suitable for the plasticinsert are polyester resins, or copolymers of styrene. These are essentially thermosetting resins which, though liquid, can be reinforced by the addition of a mineral type clay, talc or calcium carbonate fillers to develop the required resiliency in the uncured state. Such plastic material can be cured at room temperature by the use of a peroxide catalyst. The gel time can be adjusted by the addition of cobalt naphthenate in a proper percentage. I

Since the catalyst, accelerator and filters must be added during the blending of the basic material, the setting starts as soon as they components are integrally related. One way to inhibit the reaction is by freezing the sole inserts during storage. Another method is to use benzoyl peroxide as a catalyst and when ready for use to apply di-- ethyl or di-methyl aniline solution to the surface.

While there have been shown what at present are considered to be preferred techniques for forming shoe-supporting inserts, it will be obvious that many changes and modifications may be made therein without departing from I the essential spirit of the invention. It is to be understood that while the invention has been disclosed in connection with inserts for menis shoes,.the invention is equally applicable to shoes for women. It is intended therefore in the appended claims to cover all suchchanges and modifications as fall within the true scope of the invention.

What is claimed is:

1. The method of producing afoot-supporting shoe insert comprising the steps of molding in a former an uncured insert blank formed of plastigel to take on the shape of the plantar area of the foot, said plastigel having a curing temperature in excess of 300 F., said former being impervious to said curing temperature, curing said impressed insert while in said former to form a finished insert which permanently maintains said impression without distortion and is resilient and flexible.

2. The method of producing a foot-supporting shoe insert comprising the steps of placing an uncured insert blank having the contour of a sole and formed of plastigel into a former whose sole dimensions correspond substantially to that of a standard shoe appropriate to the foot of a wearer, securing said former with the insert therein to the foot of the wearer, whereby when the wearer walks the insert blank is shaped to conform to the plantar area of the wearers foot, heating said impressed insert while positioned in said former, and rapidly cooling said heated insert while positioned in said former to form a finished insert, which permanently maintains said impres sion Without distortion and is both resilient and flexible.

3. The method of producing a foot-supporting shoe insert comprising the steps of placing an uncured insert blank having the contour of 'a sole and formed of plastigel into a rigid former whose sole dimensions correspond sub-' stantially to that of a standard shoe appropriate to the foot of a wearer, strapping said former with the insert therein to the foot of the wearer, whereby when the wearer walks the insert blank is shaped to conform to the plantar area of the Wearers foot, heating said impressed insert dielectrically while positioned in said former, and rapidly cooling said heated insert while positioned in said former to form a finished insert.

4. The method of producing a foot-supporting shoe insert comprising the steps of placing an uncured plastigel insert blank having the contour'of a sole into a slipperlike former whose dimensions correspond substantially to that of a standard shoe appropriate to the foot of a wearer,

' strapping said former with the'insert therein to the foot of the wearer to shape 'said insert by causing the' wearer to walk with said former, removing the foot from the former, heating said former with the shaped insert therein to cure said insert, rapidly cooling said heated insert by immersion in water, and inserting the completed insert into the standard shoe. I a

5. The method set forth in claim 4, further including the step of covering said completed insert.

References Cited in the file of this patent UNITED STATES PATENTS 2,206,029 .Daniels July 2, 1940

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