CA2183905A1 - Resilient molded shoe heels - Google Patents

Abstract

In a new method of molding a shoe heel a molding material is injected into a shoe heel mold while one or more chamber forming rods or tubes protrude into the heel portion, the rods or tubes being removed usually just prior to the final setting of the molding material while this is still relatively easy to do. The open ends of the chambers that are formed are closed by suitably shaped plugs. The rods or tubes thus form a corresponding number of enclosed hollow chambers which provides a different degree of resilience to heel strike forces at the location of the chambers. The invention also includes apparatus for making such heels, and the heels when so made. The molded body may comprise a sole with an integral heel portion.

Description

= --2 i 83~05 Resilient Molded Shoe Heels ~i~ld Df thP InVpntion This invention relates to methods and apparatus for the production of molded shoe heels, and to molded shoe heels made by such methods and/or with such apparatus. It relates particularly to methods and apparatus for the production of molded shoe heels with a selectable amount of resilience toward the vertically acting forces on the heel resulting from heel strike, and to resilient molded shoe heels made by such metllods and/or with such apparatus.
E~ackqround of the Tny~ t; ~-n In some forms of footwear the shoe outer sole and the heel, constituting the shoe surfaces that contact the ground, are formed as a unitary member, while in others they are formed separately and subsequently attached to one another. Such a unitary member is still often referred to as a "sole", and in this specification and claims the term is used in this sense, the separate parts being referred to individually as the ~sole portion" and "heel portion".
Many proposals have been made hitherto to produce footwear in which the resilience of the soles, particularly in the heel portions thereof, is selected in accordance with the type of person and use for which the shoe is intended.
Such selection of the resilience may consist of the choice of a particular degree for the-2entire sole ;n~ ;ng the , 2 ~
heel portion, and/or the choice of particular degrees of r,o~; l; Pn~e ~or dif ~erent speci~ic parts o~ the ~ole . The choice for the heel portion is of particular importance, since the ma ~ ority o~ the impas~ts with the ground to which 5 the wearer' s foot is subjected are through the heel portion .

For example, U.S. Patent No. 4,043,058 to Hollister et al discloses an athletic training shoe 10 employing a foam core sole layer and an apertured sole layer, the latter being sandwiched between a harder outer sole layer and the shoe upper. The apertured sole layer has a plurality of strategically placed vertically-extending apertures in order to provide lightweight 15 cushioning at these locations, and preferably is a heel-lift layer positioned below a an ;ntP -~;ate sole layer having a soft resilient foam core ~ULL~Ullded by a harder border portion.

U.S. Patent No. 4,245,406 to Landsay et al discloses an athletic shoe in which an upper and a pre~ormed rubber outsole are~ j oined by means of a molding operation via a ~ormed polyurethane inj ection-molded midsole, the midsole having a horley-cornb like structure in the region behind the metatarsal area, the spaces in the honey-comb being filled during the molding with foamed polyurethane .

~ 2 3 8~
U . S . Patent No . 5 ,117, 566 discloses a shoe construction with a sole ~ormed o~ rn~llm~t1 c tubes . Two separate rows of such tubes, with the tubes arranged parallel to one another and extending transversely to the 5 longitudinal axis of the shoe, are l ~m;n~t~fl to the opposite sides of a first resilient polymeric layer, and two further layers are then laminated to one of the sets, and to one another, to complete the sole, the layers being of different selected durometer hardnesses to obtain the 10 desired degree of cushioning.

There have been a n~Lm.ber of prior proposals for shoes in which hollow air-receiving cha!mbers formed in the sole and in the side wa] ls can be pressurized as required 15 via connecting passages and air valves to change the resilience of the sole and/or to press the shoe side walls against the ankle f or increased support .

All of the foregoing proposals require a 20 multistep operation for the manufacture of the sole, while a further step or steps are required for its incorporation into a shoe by ,om~nt;n~ in place, or by molding to the other~ elements of the s~loe.

25 S ry of the Invention It is a principal object of the present invention to provide a new method o~ making a molded shoe heel with which the degree of regilience to forces acting vertically 2 i 839~
.
through the heel can reaà.ily and economically be selected during its manuf acture .
It is another principal obj ect to provide apparatus f or molding such a shoe heel .
It is a further obj ect to provide a new molded shoe heel with which the degree of resilience to forces acting vertically througl~ the heel has been readily and economically selected during its manufacture.
In accordance with the present invention there is provided a method of molding a shoe heel comprising:
providing at least one chamber forming member extending from a side wall in a mold cavity of a shoe heel portion mold;
injecting a molding m~t~r;~l into the mold cavity to form a molded heel body therein;
when the molding material has set to a predet~rm; nf~l de~ree removing the chamber forming member or members to leave a corresponding chamber or chambers in the shoe heel portion, thereby providing a different degree of resilience to heel strike forces acting vertically through the heel at the location of the cham.ber or chambers; and removing the shoe heel f rom the mold .
Also in accordance with the invention there is provided a molded shoe heel comprising a body of molded material having at least one hollow chamber formed therein ~ 9 ~ 9~
.
by a chamber forming member extending from a side wall of a shoe heel mold into the heel mold chamber during the molding process and providing increased resilience to heel strike f orces acting through the heel at the chamber 5 location.

Further in accordance with the invention there is provided apparatus f or ml~lding a shoe =heel comprising:
a shoe heel mold having a mold interior of 10 finished molded shoe heel shape;
means for inserting and withdrawing at least one chamber forming member into the mold interiori and means for in~ecting a body of molding material into the mold interior to form the heel thereln, When the chamber forming member or members leave openings of corresponding shape in the side wall of the molded heel, the method includes the step of closing each such opening with a closure member. The mold may be a 2C sole mold in which the molded body comprises a sole with an integral heel portion for incorporation into a shoe in a subseguent operation, or it may be a shoe mold with which the upper side of the mold cavity is closed during a molding operation by a shoe upper to which a molded sole 25 and integral heel is attached by and during the molding operation, E~ach chamber forming member may be a solid rod, or alternatively may be a hollow tube forming a chamber of corresponding cross section in the molded heel body .

\De~crlption of the Drawing~

Figure 1 is an exploded perspective view showing a boot upper in place on a la~t and also ~howing apparatus in 5 accordance with my invention comprising a sole mold for forming an outer sole on the boot upper by a molding operation;
Figure 2 is a part side elevation, and part cross section on the line 2-2 of Figure 1, of the lower portion 10 of a boot, comprising the boot upper of Figure 1 after an outer sole with an integral heel portion that is a first embo~iment of the invention has been molded in place thereon;
Figures 3 and 4 are horizontal cro~ ~ections of the 15 heel portion of a boot that i~ another embodiment of the invention employing hollow tube~ to form resilience-increasing ~h: s, Figure 3 showing the tubes s~:ill in place and Figure 4 ~howing the resultant heel portion;
Figure 5 is a horizontal cross section similar to 20 Figure 3 and showing another arrangement of chamber-forming rods that can be employed to produce a further embodiment;
Figure 6 is a perspective view of another form of sole mold that can be employed in accordance with my invention;
Figure 7 is a plan view of a sole mold of the kind 25 shown in Figure 6 and showing the use of overlapping tran~versely ,o~t~n~l; ng parallel tube~; in the formation of the chambers;
Figure 8 is a side elevation of a heel porti~n produced by use of the apparatu~ of Figure 7;

2~ ~39~5 Figure 9 is a plan view similar to Figure 7 showing the u~e of parallel rlon-circular cross section rods in a particular angular orientation in the formation of the chambers; and Figure 10 is a side elevation similar to Figure 8 of a heel portion produced by use of the apparatus of Figure 9.
The same ref erences are used f or the same or similar parts irl all the figures of the drawings wherever that is possible.
Description of the Pr~f~rr~d r o~-- ts For convenience in terminology the term " shoe "
that has previously beerl used and is used subsequently herein, in both the description and the claims, will be understood to include also ~boot~ within its scope, the latter term being used ~Then desirable, for example in relation to Figure 1 which clearly shows a boot and not a shoe .
Work shoes and boots differ in important respects from casual, sports and high-style footwear, in that inherently they are required to be durable and protective, and hence must be made of durable materials. Also, they either are bought by employees who tend to regard them as utilitarian products for which they may therefore be reluctant to spend more than is necessary, or they are supplied to the employee by an employer who buys in quantity, with the result that they tend to be more price sensitive than non-work footwear. Nevertheless, there i8 the deslre to provide footwear that is as comfortable a~
possible to wear and to ~alk in despite this price constraint. The provision of a durable sole and heel 5 necessitates the use of molding materials that when f inally molded and set are also ~omewhat rigid, and it is difficult with such materials to provide economically a work shoe or boot with a heel of sufficient resilience at the area of heel strike. Although as particularly described herein 10 the invention is directed pr;n~;p~l ly to methods and apparatus for the production of work footwear, and to such footwear when produced by the methods and apparatus, it will be apparent to those skilled in the art that nevertheless the invention is applicable generally to all 15 types of footwear incorporating a molded heel in providing an easy and economical way of selecting during the manufacture the degree of resilience of such a heel.

Ref erring now to Figure 1, a pref ormed boot upper 20 10, made of leather or other suitable equivalent material, is mounted on a metal last 12 together with an insole 14, the two being attached to one another by tacks 16. In other embodiments the upper 10 and the insole 14 may be attached by string lasting or by use of a thermo-setting 25 plastic adhesive. The tacked turned-in lower edge portion of the upper is prepared in known manner to receive a molded-in-place sole 18 ~Pigure 2) by abrading the portion and coating it with a layer of sealing material 20 that prevents the molding material from penetrating too deeply into the leather upper while permitting adequate adhesion thereto. The last and the mounted boot upper are pressed into a metal sole mold 22, which f its tightly around the edge of the upper 10, until the turned-in edge portion 5 butts firmly against an internal circumferential ridge 24, 90 that a tightly closed mold cavity is thus formed of the final shape for the boot sole with an integral heel portion. The bottom surface of the mold cavity is provided wlth upstanding rldge8 26 to produce a 10 corr~p~n-q~ n~ tread pattern in the f lnished boot sole .
The mold is provided with an in~ection inlet 28 through the molding material is in~ected into the mold cavity.

In this embodiment the sole mold 22 has mounted 15 in the side wall of the heel portion thereof two cylindrical chamber-forming rods 30 that extend hori~ontally and parallel to one another on opposite sides of the sole central longitudinal axis 32, equally spaced from the axis. The rods are a close sliding fit in 20 respective openings 34 in the end portion of the side wall and are attached to a crosshead 36 to constitute a molding sub-assembly enabling them to be moved into and out of the sole mold interior, as required, by means of a moving mechanism of any suitable kind (not shown) attached to the 25 crosshead by a connecting rod 37. A suitable flowable molding material, such as a foaming polyurethane, is injected into the mold cavity through the inlet 28, when it immediately expands and fills the entire mold cavity. At a suitable point in the molding cycle after the molding _ g _ 21 ~39()5 mater1al has begun to set, but before lt has completely set, the mGving mechanism is operated to withdraw the rods so as to leave, as shown in Figure 2, two parallel cylindrical chambers 38 of the size required to impart the 5 desired increased resilience to the rear part of the heel portion. At the conclusion of the setting cycle, after the molding material has solidified and cured to the required extent, the boot is removed from the mold and the open en(ls o~ the chambers 38 closed by the insertion 10 therein of closure members constituted by adhesive coated plugs 40. The chambers 38 in the somewhat rigid material of the sole increases the resllience of the heel portion by increasing its compresslbility at this location.

The size of the chambers 38 can be controlled by a number of factors, such as the dimensions of the rods and the extent to which they protrude into the heel portion, as well as the length of the plugs 40, any increase in which shortens the chambers as well as moving the centre of 20 action of the chambers further inwards from the back edge of the heel portion. The cGmpressibility is also affected by the transverse spacing of the chambers and by their cross section, which is not necessarily round but can instead be of any selected non-circular shape, for example 25 SG~uare, hexagonal, rectangular or oval. Any ~ mhln~t;f~n of different cross-sections can also be employed. The compressibility is further affected by the number of chambers employed, and although in this embodiment two rods are employed to produce two parallel chambers, in other ~ ~ 8390~
embodiments a single chamber could be e~ployed, or more than two chambers. Another variation can be introduced by taperlng the rods along their lengths. Rods that taper from the rear of the heel portion towards the front thereof 5 are simple to manufacture and are easily withdrawn; it is also possible to reverse taper them from the front to the rear, but this would re~ulre a more complicated molding sub-assembly in which th~ rods are collapsible to permit their withdrawal.

Figures 3 and 4 illustrate a further embodiment in which two annular cross section chambers 38 are formed using a palr of parallel hollow cylindrical tubes 30 in plac~ of the solid rods of the previously described 15 embodiment . The molding material f lows into the interior~
of the tubes, so that when they are withdrawn they leave behind solid cores 42 of the molded material. The interiors of the tubes are provided with bleed holes 44 to permit escape of air and entry of the molding matérial, and 20 with metal end plugs 46 t~ define the exterior surface of the molded heel wall at these locations. With this embodiment the plugs 40 are also annular in cross section to close the annular spaces at the chamber ends.

Figure 5 shows an embodiment in which at least three rods or tubes are used, at least one of which is inserted along the boot longitudinal axis while the other two or more are inserted from respective sides so as to be ; n~l; n~l at re8pective acute angles to the axis .

2 ~ 83~05 Figure 6 shows a further embodiment of both the apparatu6 of the invention, and of the molded shoe heel portion The metal sole mold is made in three separable parts, comprlsing a bottom portion 22a and two side 5 portions 22b. Two parallel rods (or tubes) 30 are fixed p-:L~ tly to the inner wall of each of the side portions 22b 60 as to extend transversely of the longitudinal axis 32. In this embodiment the rods register with one another 80 that the ends of the rods butt against one another when 10 the mold is clo~ed to fol-m a chamber that initially extends completely through the heel until its ends are closed by closure plugs 40. Upon completion of the molding operation the mold side portions are moved apart to withdraw the rods from the molded heel.

Figures 7 and 8 show emb--~llmPnt~ using the mold apparatus of Figure 6, in which the chamber forming members are at least two hollow tubes, one of which is f ixed to a respective mold member portion inner wall, the two members 20 being parallel and of lergth to overlap one another.
Figure 7 shows the arrangement during the molding operation, while Figure ~ shows the resultant heel portion in side elevation.

Figures 9 and 10 show further embntl;-- t~ using the mold apparatus of Figure 6, in which the chamber forming members are two sets each of a plurality of parallel rods 30 of non-circular cross section, each set being fixed to a respective mold portion inner wall. The two sets register with one another so that the rod ends butt against one another at the longitudinal central axis 32. In particular each rod 30 is of elongated oval cross section so as to have a longer dimension and a shorter 5 dimension at right angles to one another. The members are disposed parallel to o~e another and; n~-l; nf~.l so that the surfaces of the chambers defined by the cross section longer dimension, which are also the surfaces of larger surface area, are at least approximately perpendicular to 10 the direction of impact of heel strike forces on the heel, which direction is indicated by the arrow 48 in Figure 10.
Rods of rectangular cross section could instead be employed, but an oval cross section is preferred to avoid the f ormation of sharp corners .

Materials other than foamed polyurethane can of course be used for the molded sole, such as for example, a rubber, polyvinyl chloride material, or ~h~r~plA~tic vinyls or urethanes . The factors that must be ~ ~)n~ ored 20 in obtaining the select:ed resilience include the molding material, since its choice will present many other variables to be considered, such as the temperature and pressure at which it is in~ected, its viscosity and the rate of change thereof during the molding cycle, the size 25 of the sole and particularly of the heel portion, and the rate of setting and curing of the material. All of these factors can be readily and economically determined and ad~usted by means of a number of tests until the re~uired result is obtained. The invention has been described as ~1 83~D~
applied to a molded in place sole, but it ha~ equal application to a unit sole where the sole is preformed and then cemented to the upper.
Although in the embodiments described above the boot upper 10 and the insole 14 are tacked to one another when installing on the last 12 80 as to be ready for direct attachment of the sole, the invention can also be used in the manufacture of shoes and boots with other upper constructions, such as stitch downs, Goodyear welts, California littleways and McKays, and with other methods of assembly, such as string lasting, slip lasting and Cc '; n~ .

Claims (23)

1). A method of molding a shoe heel comprising:
providing in a mold cavity of a shoe heel portion mold extending from a side wall thereof at least one chamber forming member;
injecting a molding material into the mold cavity to form a molded heel body therein;
when the molding material has set to a predetermined degree removing the chamber forming member or members to leave a corresponding chamber or chambers in the shoe heel portion, thereby providing a different degree of resilience to heel strike forces acting vertically through the heel at the location of the chamber or chambers; and removing the shoe heel from the mold.

2). A method as claimed in claim 1, wherein the chamber forming member or members leave openings of corresponding shape in the side wall of the molded heel, and including the step of closing each such opening with a closure member.

3). A method as claimed in claim 1, wherein the mold is a sole mold in which the molded body comprises a sole with an integral heel portion for incorporation into a shoe in a subsequent operation.

4). A method as claimed in claim 1, wherein the mold is a shoe mold with which the upper side of the mold cavity is closed during a molding operation by a shoe upper to which a molded sole and integral heel is attached by and during the molding operation.

5). A method as claimed in claim 1, wherein each chamber forming member is a solid rod forming a chamber of corresponding cross section in the molded heel body.

6). A method as claimed in claim 1, wherein each chamber forming member is a hollow tube forming a chamber of annular cross section in the molded heel body.

7). A method as claimed in claim 1, and comprising at least two parallel chamber forming members spaced transversely from one another on opposite sides of a sole longitudinal axis and parallel to that axis.

8). A method as claimed in claim 1, and comprising at least two parallel chamber forming members spaced longitudinally from one another and extending transversely to a sole longitudinal axis.

9). A method as claimed in claim 1, and comprising at least one chamber forming member extending along a sole longitudinal axis, and at least two chamber forming members extending toward one another and inclined to the sole longitudinal axis.

10). A method as claimed in claim 1, and comprising at least one chamber forming member extending transversely to a sole longitudinal axis, each member being of non-circular transverse cross section with a longer dimension and a shorter dimension at right angles to one another, the member being disposed so that a chamber surface defined by the cross section longer dimension is at least approximately perpendicular to the direction of heel strike forces on the heel.

11). A molded shoe heel comprising a body of molded material having at least one hollow chamber formed therein by a chamber forming member extending from a side wall of a shoe heel mold into the heel mold chamber during the molding process and providing increased resilience to heel strike forces acting through the heel at the chamber location.

12). A molded shoe heel as claimed in claim 11, and comprising part of a shoe sole with an integral heel portion for incorporation into a shoe in a subsequent operation.

13). A molded shoe heel as claimed in claim 11, wherein an opening from the chamber to the shoe heel side wall is closed by a separate closure member.

14). A molded shoe heel as claimed in claim 11, wherein the chamber contains a solid core formed by a tubular chamber forming member.

15). A molded shoe heel as claimed in claim 11, and comprising at least two parallel chambers spaced transversely from one another on opposite sides of a sole longitudinal axis and parallel to that axis.

16). A molded shoe heel as claimed in claim 11, and comprising at least two parallel chambers spaced longitudinally from one another and extending transversely to a sole longitudinal axis.

17). A molded shoe heel as claimed in claim 11, and comprising at least one chamber extending along a sole longitudinal axis, and at least two chambers extending toward one another and inclined to the sole longitudinal axis.

18). A molded shoe heel as claimed in claim 11, and comprising at least one chamber extending transversely to a sole longitudinal axis, each chamber being of non-circular transverse cross section with a longer dimension and a shorter dimension at right angles to one another, the chamber being disposed so that a chamber surface defined by the cross section longer dimension is at least approximately perpendicular to the direction of heel strike forces on the heel.

19). Apparatus for molding a shoe heel comprising:
a shoe heel mold having a mold interior of finished molded shoe heel shape;
means for inserting and withdrawing at least one chamber forming member into the mold interior; and means for injecting a body of molding material into the mold interior to form the heel therein.

20). Apparatus as claimed in claim 19, wherein each chamber forming member is a solid rod.

21). Apparatus as claimed in claim 19, wherein each chamber forming member is a hollow tube.

22). Apparatus as claimed in claim 19, wherein each chamber forming member is connected to a respective crosshead member by which it is moved into and out of the mold interior.

23). Apparatus as claimed in claim 19, wherein each chamber forming member is fixed to an internal wall of a respective mold portion and is moved into and out of the mold interior by movement of the respective mold portion.