1. COMPOSITE STOCK FROM WHICH TO CUT SHOE BOTTOM COMPONENTS COMPRISING A SHEET OF DIE-CUTTABLE INSOLE MATERIAL HAVING OPPOSITE MARGINS AND A MAJOR SURFACE AREA MANY TIMES THAT OF THE COMPONENTS TO BE CUT THEREFROM, A PLURALITY OF DIE-CUTTABLE THERMOPLASTIC SHANK STIFFENER BLANKS ARRAYED ON AND ADHERED TO SAID SHEET, SAID SHANK STIFFENER BLANKS EACH: (A) HAVING A LENGTH SUBSTANTIALLY LESS THAN THE DISTANCE BETWEEN SAID OPPOSITE MARGINS OF SAID SHEET; AND (B) BEING SO DISPOSED RELATIVE TO SAID OPPOSITE MARGINS OF SAID SHEET THAT ONE END OF ANY SELECTED STIFFENER BLANK IS SUBSTANTIALLY CLOSER TO ITS NEAREST MARGIN OF SAID SHEET THAN IS THE OTHER END OF THE STIFFENER BLANK TO ITS NEAREST MARGIN OF THE SHEET.
Dec. 2, 1969 G. F. JONAS SHOE MANUFACTURE 2 Sheets-Sheet 1 Filed May 17, 196s Fics.
Dec. 2, 1969 G. F. JONAS 3,481,820
SHOE MANUFACTURE Filed May 17, 1965 2 Sheets-Sheet 2 United States Patent O 3,481,820 SHOE MANUFACTURE Gilbert F. Jonas, Nashville, Tenn., assignor to Geneseo, Inc., Nashville, Tenn., a corporation of Tennessee Filed May 17, 1963, Ser. No. 281,218
Int. Cl. A43b 9/00 U.S. Cl. 161--39 2 Claims The invention relates generally to shoe manufacturing, and particularly to stiffening the several portions of shoes which require it.
It is common in shoes, especially those with substantial heel height, to provide, between the insole and the outsole, some means of stiffening the shank. Heretofore, this has most commonly been achieved by a piece of steel, pre-bent to the undulatory profile of the plantar surface of the last on which the shoe is to be made. Steel Shanks are usually nailed in place with or without (depending upon the sole materials) a tuck of fiber or other material less stiff than the steel shank, but stiffer than sole material. Such a tuck not only distributes the stiffness, of the steel shank, over a greater area than that of the steel shank, but also provides a foundation to mitigate any tendency for the steel shank to rub its way into or through the adjacent sole material.
As indicated above, steel shanks are shaped to conform substantially with the profile of the last (and shoe) in the direction normal to plantar surface. This imposes a serious limitation on the versatility of a given steel shank. While it does not necessarily preclude steel Shanks of given profile from being usable on more than one last, it does require that steel Shanks of different proles be provided for shoes of substantially different heel heights or of radically different lengths. Hence, the shoe manufacturer is confronted with the necessity for carrying an inventory of several different shapes and sizes of steel Shanks, and of running short of one while overstocked with another.
It has heretofore been proposed to use plastic shank stiffeners. One effort in this direction involved injection molding of the Shanks to the desired plantar profile; and hence was no solution to the inventory problem above mentioned in connection with steel Shanks. Furthermore, since it requires a different mold for each size and shape of shank, the tooling expense was even greater than that for steel Shanks, and it is necessarily priced out of the market.
Another effort toward the use of plastic Shanks involved the use of swatches of fiberglass-reinforced thermosetting resin laid uncured in the shoes, conformed to profile, and then heated to cure it in situ. This effort has run afoul of operational difficulties with respect to preventing the setting, or partial setting, of the resin while in storage, or otherwise before it is in proper place. Suitable thermosetting material seems unavailable without some such characteristic as: having to be maintained under refrigeration to prevent premature curing; gumming-up of lingers, tools and adjacent shoe parts, in the processes of handling or application; requiring setting temperatures of such magnitude that leather and other shoe materials are thereby adversely affected; or requiring preforming in separate molds in order to provide adequate cure-all of which is either so expensive or so time-consuming, or both, as to militate against use of thermosetting resin.
A further effort to find a substitute for the steel shank involved replacing the usual binders in fiberboard with thermoplastic binders. In theory, the thermoplastic binders of the board were supposed to be softened when exposed to heat, so that the fiber within the board can be repositioned by exposure to pressure in male and female 3,481,820 Patented Dec. 2, 1969 ICC molds. This proposal has several weaknesses which are yet to be overcome. Very high temperatures and prolonged exposures are needed to overcome the insulating values of the fiber before the internal thermoplastic is softened; high pressures are needed in order to move the fibers around within the softened thermoplastic, and this requires the use of male and female molds precisely shaped to the desired ultimate contour, which is quite expensive; Moreover, the resultant product has a sharp and critical fracture point. The molded fiber is quite rigid, and, when exposed to undue pressure or shock, tends to break rather than to yield.
Accordingly, it is a primary object of the present invention to provide a shoe shank stiffener and a method of utilizing the same, whereby the stiffener can be contoured in situ and yet avoid the problems and difficulties aforesaid.
The invention contemplates generally the provision of shank blanks made of thermoplastic material without regard to profile (in the direction normal to the plantar surface) and with little (except for economy) regard for marginal contour; and conforming to the bottom of a last by softening and setting in situ. This is conveniently and preferably accomplished by first attaching-as by means of thermosetting adhesive-a thermoplastic shank blank to a shoe bottom component such as an insole or a sock liner, or a thin sheet of flexible, but relatively unstretchable, material (e.g., fabric or paper); connecting the composite blank in proper position on a last; softening the plastic component until it is readily deformable; While so softened, conforming it to the plantar profile of the last, and maintaining it so conformed until it has reset to that profile. On the other hand, in some cases, the thermoplastic shank blank can be connected to a last, and so conformed, without previously connecting it to a shoe bottomcomponent.
Thermoplastic material, as the term is used herein, means a material which can be melted or at least softened by heat alone, which sets to a solid state by removal of heat, after having once been set can be remelted (or resoftened) and then reset, and the process of melting (or softening) and setting can be repeated many times.
The softening of the thermoplastic shank blank is preferably accomplished by heating it to a temperature which is sufliciently above its softening point that it is readily conformable to the plantar profile of the last, but sufficiently below its melting point that it remains intact. Depending upon the thermoplastic material employed, such temperature may or may not exceed its plastic memory point. Where, in the process of shoe manufacture, the plastic shank will subsequently be exposed to heat or other softening agencies without being positively held to the profile of the last, it is preferred that the plastic shank blank be heated beyond its plastic memory point when originally conformed to the plantar contour of the last. However, in the usual shoe manufacturing operations, snch heating (subsequent to conforming to the profile of the last) of the shank will not normally occur until after the upper has been lasted over, and fastened to, an insole or the like. Consequently, if (as hereinafter disclosed) the plastic shank blank has a width which takes its margins under the overlasted upper, the same means which secures the upper in position also prevents the plastic shank, when resoftened, from substantially departing (by force of memory) from conformity with the plantar profile of the last. While such is not indispensable, it is desirable to employ a thermoplastic material which, consistent with other conditions, can be softened beyond its plastic memory point at the time it is conformed to the plantar profile of the last.
Plastic memory point, as the expression is herein used, means the kind and degree of softening which eliminates the thermoplastic blanks memory of previous molecular orientation and its tendency, upon resetting, to resume a previous shape.
The heating of the thermoplastic shank blank, while on the last (with or Without an intervening shoe component), to the temperature necessary to achieve the desired softening, can be accomplished by any suitable means. The precise temperature depends upon the thermoplastic material of which shank blank is made, but is, in any event, less than the temperature which would have a deleterious effect either upon the shoe bottom component to which the blank is attached, or upon the material used to attach it. Preferably, the shank blank is made of thermoplastic material which is soft enough to conform easily to the last profile at a temperature not in excess of about 250 F.
The majority of thermoplastic materials which are conventionally used in injection molding operations are thus suitable. Typical examples are:
An acrylonitrile-butadiene-styrene copolymer (such as one commercially available from Marbon Chemical Co. under the designation Cyco1ac) having a plastic memory point of about 200 F., a softening point of about 160 F., and a melting point of about 250 F.
A rubber-modified polymethyl methacrylate resin (such as one commercially available from Rohm & Haas under the designation Implex) having substantially the same softening characteristics as Cycolac.
Polymeric amide molding resins (such as those available from the DuPont Company under the designation nylon) which have plastic memory points of between 190 C. and 250 C., softening points between 170 C. and 235 C., and melting points between 215 C. and 264 C.
A polyacetal molding resin (such as one commercially available from the DuPont Company under the designation Delrin).
A polycarbonate molding resin (such as one commerially available from General Electric Company under the designation Lexan The shank blanks are preferably premolded without regard to the final prole to which they will be conformed. For example, for economy of manufacture, they may be at, or substantially so. On the other hand, they may be die cut from sheets of the chosen thermoplastic material. Where desired, they may be molded with some portions thicker than others, or with ribs, recesses or feathered edges, so as to provide relative stiffness in one region (as at the center) and relative flexibility in another region (as at the edges). Such molding may be accomplished either by injection molding individually or in multiple; or by rolling or stamping a softened sheet to emboss and/ or deboss it appropriately, and then separating the blanks from the surrounding sheet substance.
Any convenient source of heat may be employed for softening the shank blanks. Electrically energized radiant heating units appear to be most convenient. Such units may be in the form of conventional heat lamp or so-called Calrod units, which may be masked, if desired, to confine the heat rays emanating therefrom to the laminated area of the shank blank or part thereof.
As indicated hereinbefore, the shank blank is preferably laminated to a shoe bottom component, such as an insole or part-insole, or equivalent. To accomplish such lamination, it is essential to choose an adhesive means which will not release itself, or otherwise become ineffective, upon exposure to the temperature at which the shank blank will be raised during the softening operation. Sodium silicate, casein cement, or any other thermosetting adhesive, is recommended, although a thermoplastic adhesive which is not deleteriously affected by the temperature at which it will be exposed during the softening operation on the attached shank blank, may be used.
After the laminate of shank blank and shoe bottom component has been attached to a last and the shank blank sufficiently softened, it will frequently wilt (if the last is held bottom side up) into conformity with the prole of the plantar surface of the last, =but in any event gentle pressure is sufficient t0 bring about such conformity. Once so conformed, the last with the conformed laminate attached thereto may be placed in a press of the type conventionally used in the manufacture of cemented shoes, and thereby held in the desired conformity until the shank blank has reset to that conformity. Such resetting can, of course, be accelerated by quenching the shank blank, as by moving it through a zone whose ambient temperature is substantially below the softening point thereof. Indeed, such quenching occurs to some degree when the softened shank is removed from the zone of heating and exposed to room temperature. The expression a laminate, as used herein, means a pluri-ply article in which the respective plies are adhered together with a major surface of one ply in face-to-face relationship with a major surface of another ply. As used herein, the term major surface means a. surface Whose area is the product of length and width in contra-distinction to a surface whose area is the product of thickness and length or width.
The magnitude of the pressure applied in the press depends upon the softness of the conformed shank blank when it is put into the press. If the blank was heated above its plastic memory point, and the blank is in proper profile at the time it is put in the press, the pressure of the press may be very slight-indeed, the press can be dispensed with if proper precautions are taken to prevent accidental movements until resetting is complete. On the other hand, where the shank blank, after conforming to the profile of the last, retains a memory of its previous shape, sufficient pressure must be applied in the press t0 balance the memory urge of the plastic to move out of conformity with the last bottom profile during resetting. The degree of pressure is thus proportional to residual memory in the plastic. The higher the temperature was raised above the softening point, the less the residual memory-and the less the pressure required. Since pressure is usually much cheaper than heat, the economics favor the lowest temperature at which proper conformation can -be achieved, For instance Cycolac resins conform easily at a temperature of about F., and Delrin at about 170 C.; and it is advantageous to conform at those temperatures in spite of the greater press pressure required, if the plastic shank blank has been prelaminated (with thermosetting adhesive) to a shoe bottom component.
Having thus generally described the invention, reference may now be made to the accompanying drawings for a detailed disclosure of a specific embodiment thereof. In the drawings:
FIGURE 1 is a perspective view of one form of shank blank constructed in accordance with the present invention;
FIGURE 2 is a sectional view taken along line 2 2 of FIGURE l;
FIGURE 3 is a. sectional view taken along line 3 3 of FIGURE 1;
FIGURE 4 is a perspective view of a sheet of insole material to which a series of shank blanks has been laminated, and showing a cutting die superimposed upon one section of the sheet;
FIGURE 5 is a perspective view illustrating a typical arrangement during the process of softening the shank blank;
FIGURE 6 is a perspective view showing a typical arrangement for maintaining the shank blank in conformity ity with a last during the resetting operation;
FIGURE 7 is a cross-sectional view of the heel end of a last, with shank blank attached, and shows the condition of the shank blank after the operation of FIGURE 6; and
FIGURE 8 is a view corresponding to FIGURE 7, but showing the condition after the shoe upper and heel are applied by a process which includes resoftening the plastic shank at the heel seat.
In the form shown in FIGURE 1, the shank `blank is an injection molded piece of thermoplastic resin, such as Cycolac above mentioned. The marginal contour of the blank corresponds substantially to all but the fore part of the marginal contour of the insole of a shoe with which it is to be used. It will be understood, however, that the shank blank need not necessarily be of equal width, at any section, to the corresponding width of the insole with which it is used; and need not necessarily be so long as to extend entirely to the heel end of the insole.
In the embodiment shown, the shank blank is initially molded with a substantially flat surface 1, which is the surface intended to be laminated to the shoe bottom component, or, in other words, is the surface which extends upwardly in the completed shoe. The reverse side lof the shank blank is provided with an integral longitudinally extending centrally disposed rib 2, which gradually slopes toward the marginal edges of the blank so as to provide thin, -or feathered, edge portions 3 on opposite sides lof the rig 2. In order to render the shank blank as light in weight as feasible, and also to increase its response to the heat applied for softening it, the upper surface 1 may be provided with a succession of indentations 4 arranged in rows with uninterrupted longitudinally extending webs 5 between the rows, and spaced cross-webs 6 between the indentations in a given row. As clearly shown in FIGURE 3, the end portions of the shank blank beyond the rows of indentations 4 are thinned or feathered as shown at 7 and 8. It is particularly desirable to feather end 7 which, in the completed shoe, will lie immediately earwardly of the fore part tread, or, in other words, at the forward end of the shank portion.
The Shank blank illustrated in FIGURES 1, 2. and 3, is for a right shoe, but those skilled in the -art will readily understand that for the left shoe, the blanks are contoured on each side so as to be the mirror image of that shown in the drawings. Two sizes of such blanks are 4sufficient to satisfy the requirements of the entire range of womens shoe sizes; and with the addition of one 4additional size, at either end, the full range of mens sizes and childrens sizes can also be accommodated.
Given a series of performed shank blanks as shown in FIGURES 1, 2 and 3, and/or their left shoe counterparts, the preferable procedure is to liminate them to a sheet of insole material which may be fiber, leather, or any other natural or synthetic material suitable for the purpose. A strip 9 of such material, having a width at least equal to the length of the longest insole to be provided, is then laminated with a series of shank blanks 10. As shown in FIGURE 4, the `several shank blanks are preferably aligned with their heel ends adjacent one edge 11 of strip 9, and as close together at their ends 7 as may be. Between the shank blanks and the surface of strip 9, which they respectively overlie, there is interposed a film of adhesive which is either thermosetting or not adversely affected by the temperature to which the shank blank will subsequently be raised. A substantial economy may be effected by utilizing a strip 9 of sock lining material over the entire surface of which there has been applied a heavy coat of thermosetting plastic adhesive, of a character such as to firmly and uniformly adhere the shank blanks to the strip. By applying such a coat of thermosetting plastic over the surface of the strip 9, even beyond the confines ofthe shank blank, material ordinarily suitable only for sock lining is stiffened at the fore part to an extent such as to provide for good toe and fore part lasting equivalent to that accomplished by ordinary insole material, and thus eliminating the insole completely.
While, ordinarily, it is desirable to permit the adhesive between the respective shank blanks and strip 9 to set before proceeding further, such is not essential. If such adhesive is not permitted to set before proceeding further, a strip of pressure-sensitive adhesive tape 12 may be applied across the ends 7 of the several shank blanks 10, so as to overlap onto strip 9 therebeyond, and thereby hold the several shank blanks 10 sufficiently securely for the succeeding operation. In either event, the succeeding operation, according to the preferred embodiment of the process, is then to die cut the several shank blanks and their adjunct material 9 from the laminate. One or more clicking dies, such as 13, of appropriate size, is then appropriately placed upon the laminate of strip 9 and blanks 10, and subjected to a blow, such as is customary in clicking operations, in order to sever individual insole members laminated with shank blanks. In the course of so doing, it will be understood that the clicking die 13, or its counterpart, may be of size and shape corresponding with the marginal contour of the shank blank, or larger or smaller. If smaller, the clicking die se'vers away a marginal fraction of the shank blank; if larger, the marginal contour of the shank blank lies slightly within the marginal contour of the die-cut laminate, but neither the utility of the resultant shoe bottom component nor the utility of the shank blank is thereby defeated.
After having die cut the several insole-shaped laminates from strip 9, they are respectively attached to lasts. As shown in FIGURE 5, one such laminate 14 is attached to the fore part of last 15 by means of two tacks 16, so that the fore part of laminate 14 is in the nal position, with reference to the last, which it will occupy throughout the shoe manufacturing operation. As will be apparent from FIGURE 5, the shank and heel portions of laminate 14 ldo not, as shown, conform themselves to the profile of the plantar surfaces of the last at the shank and heel portions thereof. However, upon application of sufficient heat, as by means of heat lamps 17 positioned thereabove, the thermoplastic material of which the shank blank is composed begins to soften, and as it softens, it wilts into substantial conformity with the plantar prole of last 15, as well as (if properly positioned on the fore part of the last and properly cut) in conformity with the marginal contour of the last. If, at the time of so wilting, the plastic memory point of the plastic shank blank material has not been reached, the heating is continued at least until the plastic can be conformed to the plantar profile of the last, and will remain so conformable for a time suicient to transfer it (and the last) to a press. In the meantime, however, the portions of the laminate 14 rearwardly of the fore part may be gently pressed into conformity With the plantar surface of the last 15 if they have not spontaneously done so. When the shank blanks have been properly conformed, the last with the laminate 14 thereon is lremoved from the region of the heat lamp 17, and, while -maintaining the laminate 14 in conformity with the profile and contour of the plantar surface of the last, placed in a press, such as 18 shown in FIGURE 6. The press 18 is provided with a resilient diaphragm or cushion 19 which readily conforms itself to the contour of, and applies uniform pressure to, laminate 14, forcing it rmly against the plantar surface of last 15. The last with attached laminate 14 is maintained 1n the press and under such pressure until the thermoplastic material of the shank blank has reset itself in conformity with the plantar profile of the last. The last and attached laminate is then removed from the press, and the shoe manufacturing operations proceeded within the usual manner, except that it is unnecessary to attach a separate `shank stiener and the bottom filling operations are minimized.
The pressure applied by the diaphragm 19 in the press 1i8 tends to create plastic flow within the plastic blank as long as it remains soft. Such plastic may, at least partially, obliterate some of indentations 4 and, in addition, rounds the margins of the blank 1 as shown at 21 in FIGURE 7. Such rounding provides accommodation 7 for the overlasted upper, lining, and counter, as shown in FIGURE 7.
In many situations, particularly where the overlasted upper or the outsole, or both, is secured by either thermosetting or thermoplastic cement, the material of the shank blank may be resoftened before the shoe is removed from the last 15. Such softening does not ordinarily involve raising the temperature of the shank as high as its plastic memory point, but if it does, no harm is done because the shank blank is maintained in the proper relationship on the last by the same pressing tools or securing devices which hold the upper in place. Where, during such resoftening, the temperature does not reach the plastic memory point, it may nonetheless be softened to an extent such that some plastic flow occurs. Such flow will normally exist only at those regions which are overlaid by the overlasted upper, or by the outsole, or by a heel, so that in spite of the fact that thermoplastic material may have a tendency to resume the shape in which it was reset into conformity with the last, such flowing does no harm, but, on the contrary, accomplishes the beneficial result of form-fitting itself about the other shoe parts and thus, in part, eliminating, and, in part, filling, spaces which otherwise would either have to be filled with bottom filler or left vacant.
The latter is illustrated in FIGURE 8, which shows how the overlasted margins of upper 22, counter 23, and lining 24, have embedded themselves in the thermoplastic shank by forcing the plastic ow from the rounded margins 21 (see FIGURE 7) inwardly to substantially fill the interspace and provide a good seat for the attachment of heel 25. If the heel end of the shank is kept soft prior to heel attaching, the heel will form its own mating shape in the overlasted upper, so that the lines of the resulting shoe are very thin and inconspicuous at the heel.
While one embodiment of the procedure followed in the manufacture of shoes in accordance with the present invention has thus been disclosed in detail, it is apparent that many modifications and variations of the procedure Will present themselves to those skilled in the art without departing from the spirit of the invention. For eX- ample, the shank blanks may be cut to shape without first laminating them to insoles, sock liners, or other shoe bottom components; they may be temporarily attached in the proper position on a last and conformed and reset thereto without an insole, or like shoe bottom component, between them and the last bottom; but in such situations, the shank blanks are normally required to be removed from the last if an insole is to be used in the construction of the shoe. This variation is particularly desirable in the case of slip-lasted shoes, where there is no insole, as well as forV welt shoes where the shank stitfener is placed between upstanding ribs of the insole. It may also be desirable to precut the shank blanks to size, laminate them at to the outsole, and then conform such laminate to the shoe bottom during the sole laying process by the use of heat from the conventional cement activating unit. The latter eliminates the necessity of a separate operation of insole molding since the insoles can be made without any reinforcement at all, the necessary strength of the structure being supplied by the outsole and its laminated thermoplastic shank. Furthermore, the plastic shank blanks may be laminated to the outsole and conformed to the desired prole as described above in connection with insoles. The latter is advantageous in the manufacture of sandal type shoes, such as thongs, and very nude shoes, where the uppers are not lasted at all and the sock lining is applied to the interior of the shoe as by pressure-sensitive adhesives. Again, in the case of inexpensive turn type of slipper bar shoes, the shank blanks are preferably conformed to the desired profile without cementing either to an insole or an outsole, but by cementing inside the shoe after the sole has been turned,
and thereafter softening and conforming to the desired profile.
lt is obvious, of course, that the entire insole may be made of the same thermoplastic material of which the shank blank is made, i.e., so as to include the fore part as an integral part of the shank blank. In such cases, the desired fiexibility in the rfore part may be achieved without sacrifice of rigidity in the shank portion by the utilization of thermoplastic materials which are sufficiently resilient in thin sections to provide the desired flexibility at the fore part, yand yet in thicker sections, provide the desired rigidity at the shank.
Shoes constructed in accordance with the present invention have a thinner look at the sole than those constructed in accordance with previous practices. They are lighter in weight, and have an attractive molded look. The precisionwith which the shape of the shank is controllable, in accordance with this invention, gives a handmade appearance to shoes made on a production-line basis. Lightness is achieved by eliminating not only the customary steel shank, but the bulky fiber tuckheretofore deemed desirable.
Shoes constructed in accordance with the present invention, on the same last used for the construction of shoes according to conventional systems, are actually smaller on the outside without reducing their interior measurements. This is because the shank blank of the present invention is typically only about one sixteenth of an inch thick at its margins, in contrast with an average three sixteenths inch thickness of fiber-reinforced insoles, so that the external back height measurement is an eighth of an inch lower without decreasing the room inside; and comparative reduction can be made on the sideline heights. Open heeled shoes made in accordance with the present invention also have an improved appearance, in that the insole only (a sixteenth of an inch thick) need be covered, thus making the thickness the same at both the toe and the heel.
Moreover, the shank of the present invention facilitates side lasting and heel seat lasting by virtue of the lesser thickness above mentioned, as well as by virtue of the greater hardness of the insole provided by the thermoplastic shank; and it also forms a better line with fewer wrinkles at the lasting allowance. It reduces the burden on the side laster by eliminating the necessity for bringing the insole down firmly to the last.
In the embodiment above described in detail, the thicker center section provides a natural recess on both sides for the thickness of the upper, and thus minimizes the tendency for the presence of the shank stiffner to be revealed through thin outsoles; and, at the samel time, eliminates or minimizes the bottom filling operation.
Other benefits and advantages of the invention will be readily perceived by those skilled in the art, not the least of which is the economy effected in materials employed and operations eliminated, as Well as the substantial reduction in inventory heretofore necessitated by the large assortment of sizes and styles of shank stiteners heretofore required.
Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:
1. Composite stock from which to cut shoe bottom components comprising a sheet of die-cuttable insole material having opposite margins and a major surface area many times that of the components to be cut therefrom, a plurality of die-cuttable thermoplastic shank stiffener blanks arrayed on and adhered to said sheet, said shank stifener blanks each:
(a) having a length substantially less than the distance between said opposite margins of said sheet; and
(b) being so disposed relative to said opposite margins of said sheet that one end of any selected stiffener blank is substantially closer to its nearest margin of said sheet than is the other end of the stiiener blank to its nearest margin of the sheet.
9 10 2. The composite stock of claim 1 in which the shank 2,558,317 6/1951 Schwartz 36--76 stiifener blanks have a longitudinally extending centrally 2,644,250 7/ 1953 Ciaio 36-76 disposed rib OTHER REFERENCES Nielsen, L. E.: Mechanical Properties of Polymers, 5 New York, Reinhold, 1962. TP 156 P6 N5 C3.
H. HAMPTON HUNTER, Primary Examiner References Cited UNITED STATES PATENTS 2,904,838 9/1959 Phillips. 3,086,242 4/1959 Cook et a1 264-230 XR 2,173,967 9/1939 King 36-76 X U.S C1- XR 2,232,767 2/1941 Brophy 36-76 10 12 146;36 43,76;156 253;161.145