US 3256620 A
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June 21, 1966 R. E. KlNG HEEL PLUG FOR MOLDED SHOES 2 Sheets-Sheet 1 Filed Jan. '7, 1963 FIGS G MN WW m. E T R E m ATTOR N EYS June 21, 1966 R. E. KING 3,256,620
HEEL PLUG FOR MOLDED SHOES Filed Jan. '7, 1965 2 Sheets-Sheet 2 7o 6 f I \1 INVENTOR. 9 ROBERT E. KING Wm W ATTORNEYS United States Patent 3,256,620 HEEL PLUG FOR MOLDED SHOES Robert E. King, 104 Elm St., Georgetown, Mass. Filed Jan.,7, 1 963, Ser. No. 249,765 8 Claims. (Cl. 36-25) This invention relates generally to shoes having molded soles and heels and more particularly is directed towards a novel heel plug for improving the connection between the heel portion of the sole and the upper in footwear having composition treads bonded directly to the uppers.
In the shoe industry there is a growing interest in the manufacture of shoes having full rubber or plastic soles molded directly to the leather and fabric uppers. Shoes of this type are usually quite rugged, durable and substantially waterproof. vantage of being less expensive to manufacture than a conventional shoe since there is no stitching involved in securing the sole to the upper.
In practice, a filler plug is employed in the heel portion of the shoe in order to form up the heel and to reduce the amount of rubber or plastic tread material which would otherwise be needed. These plugs are conventionally formed from fibre or wood and are placed directly over the heel portion of the insole by the operator before the rubber or plastic sole is applied. This plug generally has the configuration corresponding to the finished heel but of reduced size.
Despite their numerous advantages, shoes having soles molded directly to the upper have been plagued by a high percentage of failures in and around the heel. Most of these failures can be attributed to the use of the tiller plugs. For example, if the plug, which is manually located, is applied off-center or in a skewed position relative to the shoe bottom before molding, the molding compound will be too thin on one side and excessively thick on the opposite side. Where the compound is thin, it will be over-cured with the result it will be brittle and will break easily. On the side where the compound is excessively thick, it will be undercured and the bond to the upper will not be complete. Another problem arises from the use of wood and fibre in the plug. The fibres of the plug readily absorb moisture which, under the high temperatures and pressures involved in the molding process, is driven out to form a boundary layer between the upper material and the compound. This interferes with the adhesion between these parts and, ultimately, these conditions produce a failure in the bond.
In view of the fact that plugs made from organic material have low co-eflicients of thermal conductivity, the compound immediately adjacent to the plug cure-s at a slower rate than the compound near the molded surface. Furthermore, it is the present practice to cement the filler plug directly to the insole and then mold the compound over the heel and sole. With this technique, the compound is directly bonded to the upper and to the insole entirely across the bottom of the shoe with the exception of the area under the plug. Since the plug is not mechanically locked to the upper, the bond in this area is entirely dependent upon the strength of the cement bond between the plug and the upper. However, it has been found that this sort of a bond is frequently insufficient to prevent the heel from coming away from the upper in the finished shoe.
Accordingly, it is an object of the present invention to provide improvements in the construction of shoes having soles and heels molded directly to their uppers.
Another object of this invention is to provide an improved heel insert device f-or use in footwear having directly molded treads.
Still another object of this invention is to provide a The shoes have the added ad-' ielficentering heel insert device for shoes having molded ee s.
Yet another object of this invention is to improve the connection between the heel portion of the shoe and the upper in a shoe of a molded heel construction.
More particularly, this invention features a heel insert device for footwear having directly molded soles and heels of elastomeric materials and the like. In a preferred embodiment, the heel insert has a base member which overlies the insole and dimensionally conforms to the heel portion of the insole. Preferably the base plate is attached to the insole and the lasting margin of the upper by nailing or stapling to form a rugged interlocking connection. According to the invention, the base plate has mounted thereto a raised filler portion which extends into the finished heel and interlocks with the molded composition. As another feature of the invention, the insert is formed from a material that does not absorb moisture and is characterized by a high co-efiicient of thermal conductivity to improve the curing of the composition and to eliminate bonding problems caused by the release of moisture from conventional filler plugs.
But these and other features of the invention, along with further objects and advantages thereof will become more fully apparent from the following detailed description of the invention, with reference being made to the accompanying drawings in which:
FIG. 1 is a view in perspective of a heel insert made according to the invention,
FIG. 2 is a plan view of a portion of the device shown in FIG. 1 but in blank form,
FIG. 3 is a perspective view of another portion of the device shown in FIG. 1,
FIG. 4 is a sectional view in side elevation of the heel insert of FIG. I mounted within a directly molded heel,
FIG. 5 is a cross-sectional view taken along the line 5-5 of FIG. 4,
FIG. 6 is a perspective view of a modification of the invention,
FIG. 7 is a View in perspective showing another modification of the invention,
FIG. 8 is a plan view of still another modification of the invention, and,
*FIG. 9 is a cross-sectional 9-9 of FIG. 8.
Referring now to the drawings, the reference character 10 generally indicates a heel insert device for use as a filler plug in footwear having soles of rubber or similar material molded directly to the insole and the upper. The insert comprises a flat base .plate 12 which conforms in size and shape to the heel portion of an insole 14 (FIGS. 4 and 5) to which the insert is applied. Located within the curved margins of the base plate 12 is an upright view taken along the line hat or boss portion 16 which has the general configuration of a conventional heel but of a reduced size. Across the top of the hat portion 16 is a second flat plate 1%; somewhat smaller than the base plate 12 but being slightly larger in plan than the hat portion 16 to form an overhang 20.
In practice, the insert device may be fabricated from a pair of stampings 22 and 24 (FIGS. 2 and 3). The stamping 22 shown in FIG. 2 is in the form of .a flat blank in which the base plate 12 is joined to the plate 18 by means of .a rectangular mid-section 2 6. It will be understood that the three sections of the blank 22 are folded at right angles along fold lines 28 and 3t) and assembled to the stamping 24 shown in FIG. 4. As shown, the stamping 24 comprises a curved channel member having a pair of cars 32 adapted to interlock with slots 34 formed near the marginal edges of section 26.
Preferably, the insert device is fabricated from a sheet metal, such as aluminum or steel which does not absorb moisture and which has a high co-efiicient of thermal conductivity. Although numerous other materials may be employed aluminum or steel is preferred since these materials are strong, easily worked, and relatively low in cost.
Referring now more particularly to FIGS. 4 and 5, the insert is shown mounted within the heel portion of a directly molded sole shoe. As shown, the shoe comprises the usual insole 14 and upper 36 which may be of leather, fabric or other material. In practice, the insert device is placed by an operator over the heel portion of the insole 14 so that the marginal edges of the base plate 12 are even with the marginal edges of the insole. The partly formed shoe, which will be supported on a last, is then placed on a heel seat lasting machine. This machine will pull in and wipe the lasting margins of the upper over the marginal edges of the base plate 12. This action of the heel seat lasting machine will automatically center the insert device 10 with respect to the insole in the event that the operator placed the insert askew or slightly offcenter. Once the heel seat lasting machine has wiped the lasting margins over the edges of the plate 12, a series of nails or staples 38 will be driven down through the lasting margin, through the edge of the plate 12, through the insole 14 and will be crimped back upon'itself as shown. This will provide a positive interlocking connection between the insert, the insole and the upper.
Upon completion of the lasting operation, the insole and the lasting margins, which have been properly roughened, will be coated or lightly impregnated with a suitable cement or adhesive. When the bottom surface of the shoe has been treated with a cement or adhesive, it may be dried, if necessary, before the molding opera- .tion. Thereafter, the sole is molded directly over the insole and along the lasting margin of the upper. In practice, when the insert is fabricated from metal, it is advisable to bathe the insert in a liquid cement or adhesive solution so as to coat the metal over its entire outer surface. This outer film will thus insure a proper bond between the insert and the sole material. The'molding apparatus will apply sufficient temperature and pressure to the sole to form the sole into the desired shape and vulcanize, cure or harden the sole material so as to form a firm bond between the sole, the insole andthe upper.
It will be appreciated that the overhang 20 provided by the plate 18, will interlock with the body of the molded heel to prevent the 'heel from separating from the insert. Also, it will be appreciated that the molded heel cannot come away from the upper by reason of the positive connection between the upper, the insert and insole provided by the nails. Also, it will be appreciated that the molded heel will be of substantially uniform thickness throughout since the insert will be automatically centered by the heel seat lasting machine. Thus, the sole forming compound will be uniformly vulcanized, cured or hardened. In addition, the fact that the insert is fabricated from a highly heat conductive material will cause the molding compound to be vulcanized, cured or hardened more efficiently since the heat transfer required to cure the material may be applied from both the outside of the heel and the inside facing against the insert.
In FIG. 6 there is shown a modification of the invention and in this embodiment a heel insert device 40, generally similar in size and configuration to the device 10 of FIG. 1. However, in this modification the device 40 has a flat face 42 connected to side walls 44. The rearward curved portion of the walls tapers inwardly towards the base of the device to form an overhangfor interlocking with the composition of the molded sole. From the base of the device, there extends a number of horizontal fingers 46 each terminating in a depending prong 48. The fingers and prongs are dimensioned and arranged to span the top portion of an insole 50 in such a fashion that the prongs will engage the edges of the insole as shown in FIG. 6. It will be noted that the length of the prongs 48 is less than the thickness of the insole so as not to interfere with the wearing of the shoe. In practice, the insert 40 will be assembled in much the same fashion as the insert 10 of the principal embodiment. However, in this case the operator must locate the insert in its proper position before the insert will lie flat. This will insure correct mounting of the insert to the shoe. The heel seat lasting machine may also be employed to drive nails through the lasting margin, each of the fingers 46 and through the insole in the same manner as before.
In FIG. 7 there is illustrated a furtherembodiment of the invention and in this case a heel insert device 52 is formed integral with a shank insert 54 at the rearward end thereof. As shown in FIG. 7 the device comprises the shank 54 typically made of steel or aluminum or the like. The shank, which serves as a stiffening member for the shoe, normally lies within the instep portion of the sole. The rearward end of the shank 54 forms into a flat plate 56 of the same general shape and dimensions as the base plate 12 in the principal embodiment. A raised hat portion 60 is attached to the plate portion 56 and may be formed with an interlocking overhang 62 similar to either of the first two embodiments. As in the principal embodiment, this device is self-centering since the wiper arms of the heel seat lasting machine will automatically center the device within the mid-portion of the heel. The shank 54 will be centered simultaneously. It will be appreciated that the integrated shank and heel insert will produce an extremely rugged shoe and provide extremely firm 'bond between the uppers and the molded sole.
In FIGS. 8 and -9 there is shown yet another modification of the invention and in this embodiment the heel insert is in the form of a heel filler plug 64 attached directly to an insole 66. The plug is formed with a curved wall portion 68 having its ends joined by a straight section 70 and supporting top and bottom plates 72 and 74. The top plate 72 extends rearwardly over the curved wall 68 to form the desired interlocking overhang. As best shown in FIG. 9 the wall portions 68 and 70 are formed with pronged portions 76 which lock the plug to the insole 66. The advantage of this construction is that the insole may be provided with the filler plug already attached thereby avoiding the necessity of subsequently attaching the plug to the shoe.
The invention illustrated and described herein will provide a shoe having a directly molded sole in which the heel portion is firmly united to the insert and to the upper. The insert itself is'of simple design, rugged, adapted for low cost mass production techniques. It will be apprecited that the insert in its preferred forms is compatible with existing shoe making machinery and no new machines or modifications of existing machinery is necessary to use the insert.
While the invention has been described with particular reference to the illustrated embodiment, it will be understood that numerous modifications thereto will appear to those skilled in the art. For example, a group of barbed posts may be attached to the base plate in place of the hat pontion to interlock with the heel. It will also be understood that the above description and accompanying drawings should be taken as illustrative of the invention and not in a limiting sense.
Having thus described my invention, what I claim and desire to obtain by Letters Patent of the United States is:
1. A shoe, comprising a shoe upper, an insole, a heel insert mechanically attached to said upper and said insole and a solid unitary resilient tread member bonded continuously and directly to the insole and to the marginal edges of the upper, said insert having a flat base portion overlying the heel portion of said insole, the marginal edges of said base portion being substantially even with the marginal edges of said insole, and a boss extending from said base portion into the body of said tread member in interlocking engagement therewith, said insert being formed from a material having a high coefficient of thermal conductivity.
2. A shoe, comprising a shoe upper, an insole, a heel insert mechanically attached to said upper and said insole and a solid unitary resilient tread member bonded continuously and directly to the insole and to the marginal edges of the upper, said insert having a flat base portion overlying the heel portion of said insole, the marginal edges of said base portion being substantially even with the marginal edges of said insole, and walls defining a closed hollow boss extending centrally from said base portion into the body of said tread member in interlocking engagement therewith, said insert being formed from a material having a high coefiicient of thermal conductivity.
3. A shoe according to claim 2 including a rigid shank member integral with said base portion and extending through the shoe instep between said insole and said tread member.
4. A heel insert for a shoe having an upper with a lasting margin, an insole and a solid unitary resilient tread member bonded continuously and directly to the insole and to the marginal edges of the upper, comprising a flat base portion adapted to overlie the heel portion of said insole, the marginal edges of said base portion being substantially even with the marginal edges of said heel portion, and a heel filling element extending centrally from said base portion and adapted to extend into the body of said tread member in interlocking engagement therewith, said insert being formed from a material having a high coefiicient of thermal conductivity, said element defining with said base portion a marginal flange adapted to underlie the lasting margin of the upper and to be mechanically fastened thereto.
5. A heel insert for a shoe having an upper, an insole and a solid resilient tread member bonded continuously to the insole and to the marginal edges of the upper, comprising a base portion adapted to overlie the heel portion of said insole, a plurality of fingers extending laterally from said base and terminating in a pronged end portion adapted to grip the marginal edges of said insole, and a heel filling element generally conforming to the shape of a heel but of reduced size extending centrally from said base portion and adapted to extend into the body of said tread member in interlocking engagement therewith.
6. A heel insert according to claim 5 wherein said insert is fabricated from a rigid material having a high coetiicient of thermal conductivity.
7. A shoe, comprising a shoe upper, an insole, a heel insert mechanically attached to said upper and a solid unitary resilient tread member bonded directly and continuously to the insole and to the marginal edges of the upper, said insert being fabricated from a material characterized by a high thermal conductivity coefficient, said insert being formed with a generally flat base plate underlying the heel portion of said insole, said plate having a plurality of barbed fingers depending from the underside thereof into the heel portion of said tread member.
8, An insole and heel insert assembly for a shoe having a solid unitary resilient tread member bonded directly and continuously to the insole and to the marginal edge of the upper, comprising an insole having a sole and heel portion and a heel insert attached to said heel portion and extending outwardly from the center thereof, said insert conforming generally to the shape of the shoe heel but of reduced dimension.
References Cited by the Examiner UNITED STATES PATENTS Re. 13,728 5/1914 Nolan 36-36 1,821,878 9/1931 Bradley 3636 1,920,170 8/1933 Brockman 36-36 2,023,671 12/ 1935 Eichhorn 36-245 2,125,657 8/1938 Staub et a1. 36-36 2,333,257 11/1943 Chapelle 36-35 FOREIGN PATENTS 883,036 .11/1961 Great Britain.
FRANK J. COHEN, Primary Examiner