US2658238A - Method and apparatus for molding heel lifts - Google Patents

Description

Nov. 10, 1953 A. A. R|zzo METHOD AND APPARATUS FOR MOLDING HEEL LIFTS Original Filed Jan. 5, 1949 Awthong ARizzo,

Patented Nov. 10, 1953 METHOD AND APPARATUS FOR MOLDING HEEL LIFTS Anthony A. Rizzo, East Cleveland, Ohio, assignor of one-fifth to James J. Lazna, Cleveland Heights, Ohio,

Original application January 5, 1949, Serial No. 69,298. Divided and this application November 4, 1949, Serial No. 125,561

6 Claims.

1 My invention relates in general to the manufacture of thin heel or top lifts or similar articles of the type having an integral attachment clip molded therein. More particularly, my invention relates to methods and apparatus for manufacturing such type heel lifts or similar articles.

The present application is a division of my co-v pending application Serial No. 69,298, filed J anuary 5. 1949.

It has been proposed heretofore to provide heel lifts with integral pronged attachment clips molded therein for securing it to a shoe heel. In the manufacture of such type heel lifts, however, it has been a difficult problem to prevent the formation of stock flashing or a stocking of the molding compound on the projecting portions of the clip prongs or nails, which flashing, if left on the clip nails, is apt to prevent the lift from being properly flattened down in place on the shoe heel and besides, detracts from the appearance of the finished lift. Moreover, the formation of such flashing on the projecting prongs interferes with the production manufacture of such lifts, and the subsequent removal of the flashing from the prongs entails an additional manufacturing operation which adds to the cost of the finished article.

It is an object of my invention, therefore, to provide improved methods of molding heel lifts with pronged attachment clips embedded therein whereby the clips will be uniformly positioned in the lifts and the protruding portions of the clip prongs will be substantially free of any stock flashing thereon.

Another object of my invention is to provide novel apparatus for effectively molding a heel lift of the above described character With the protruding portions of the clip prongs substantially free of any stock flashing.

Further objects and advantages of my invention will appear from the following description of a species thereof and from the accompanying drawing in which:

Fig. 1 is a perspective and Fig. 2 a plan view of a heel lift comprising my invention; Fig. 3 is a section on the line 33 of Fig. 2 Fig. 4 is an enlarged perspective view of the insert attachment clip for the lift shown in Figs. 1-3; Fig. 5 is an enlarged fragmentary sectional view of the said clip; Fig. 6 is a fragmentary sectional view of a mold according to the invention for molding the heel lift of Figs. 1-3 with the attachment clip thereof shown in position within the mold; Fig. '7 is a plan view of the said mold; Fig. 8 is a fragmentary sectional view of a modified form of mold construction and Fig. 9 is a fragmentary section of the modified heel lift formed by the said mold; Fig. 10 is a fragmentary sectional view of another modified mold construction for molding the heel lift in accordance with a modified method comprising my invention; Fig. 11 is a fragmentary section through one of the nails of a modified form of clip according to the invention; Fig. 12 is a fragmentary sectional view of still another modified form of mold and clip construction according to the invention; and Fig. 13 is a fragmentary section of the modified heel lift formed by the mold of Fig. 12.

Referring to Figs. l-3 of the drawing, the heel lift there shown comprises a conventionally shaped lift body It) made of any of the wellknown heel lift compositions, such as hard rubber, fibre, plastic or a molded fiber-rubber composition, for instance. lift body 10, in accordance with standard practice, is arched to provide a slightly cupped or concave attachment face II which serves to insure the lift edge portions fitting tight against the shoe bottom when the lift is fastened in place thereon.

The lift body I0 is provided with integral attachment means comprising a metal insert clip I2 molded in the body In for attaching the lift to the heel of a shoe. As shown in Fig. 4, the clip I! comprises a thin plate or base portion l3 of suitable metal, such as mild steel havin a thickness around 3. 2 or so. The said plate portion l3 of the clip is provided with a plurality of parallel prongs or nails M which extend from the plate portion perpendicularly to the plane and from the same side thereof, and in accurately spaced relation to each other. In the particular case illustrated, the plate portion [3 of the clip is preferably made of triangular shape in order to minimize waste of the strip stock from which the plate blanks are punched and thus reduce the cost of manufacture. The plate [3 is provided with three nails or brads M which are secured to the plate adjacent the corners thereof and spaced in substantially the same position relative to each other as the customary nail-receiving apertures in conventional type lifts. The nails H are preferably provided with serrations, grooves or other surface irregularities, as indicated at l5, for the purpose of providing a better grip with the shoe heel.

While the nails I4 may be secured to the plate l3 in any suitable way, as by welding or clamping, they are preferably riveted in place to the plate l3, the latter being clamped between upset As shown in Fig. 3, the

3 rivet collar portions I6 and rivet head portions I! of the nails. In the form of clip shown in Figs. 1-4, the upset rivet collars I6 of the nails I4 are formed with substantially flat annular under faces or shoulder surfaces I9 (Fig. which completely encircle the bases of the clip nails I4 and which all lie in a common plane and serve as bearing or seating surfaces for resting against the fiat tops of upstanding bosses in the liftforming mold. The shank portions of the nails I4 are similar to the shank portions of the conventional type nails or brads in common use at present for attaching heel lifts in place on shoe heels. A heel lift having attachment prongs in the form of such type nails will not split a smallsize wooden shoe heel when applied thereto. Nails of circular cross-section are preferred for the reason that they simplify the construction of the mold which is employed for molding the lift.

However, nails of square or rectangular crosssection may be used instead, if desired. Clips I2 of the particular type illustrated are simple to manufacture and can be made quickly and very inexpensively by machine, the nails I4 being riveted to the plate I3 while held in a jig so as to assure accurate positioning of the nails relative to each other. Such accurate positioning of the nails I4 is essential to the proper molding of the clip into the lift body III in accordance with the method of the invention.

As shown in Fig. 2, the clip I2 is molded more or less centrally within the lift body In with the nails I4 projecting outwardly from the cupped attachment face II of the lift body and preferably located in substantially the same position about the lift body (as viewed in plan) as the customary nail-receiving apertures in conventional type lifts. The nails I4 project outwardly beyond the cupped face II a distance sufficient to insure a secure attachment of the lift to the shoe heel. For this purpose, I have found a nail projection of around 1 5" or so beyond the face I I to be entirely satisfactory.

The plate portion I3 of the clip is preferably molded in the lift body I0 as close as possible (for instance around 1%" or so) to the cupped attachment face II thereof in order to provide the maximum possible thickness of lift body material on the tread side for wear purposes. To more firmly secure the clip I2 in place within the body III of the lift and to also facilitate the flow of the molding compound underneath the plate portion I3 of the clip, one or more apertures I8 may be provided, if desired, in the said plate portion I3. In such case, three such apertures I8 of circular shape may be provided, the said apertures being arranged in triangularly spaced relation with each aperture located approximately midway between a respective pair of the nails I4. In this way, a continuous web of metal is retained extending from the center of the plate portion I3 out to the region of each nail I4 for effective transmission thereto of the force of the hammer blows to which the lift is subjected during its attachment to the shoe heel.

The molding of the heel lift, shown in Figs. 1-3, is performed in a mold (Figs. 6-7) having a cavity 2I shaped to conform to the configuration of the lift body Ill. The bottom 22 of the mold is provided with a plurality of upstanding apertured bosses 23 corresponding in number (three in the particular case shown) and in disposition with the nails I4 of the clip I2, and having central apertures 24 to receive the nails I4. The bosses 23 are made around $43" or so larger in diameter than the nails I4 of the clip. In the particular case illustrated wherein the nails are of 0.054" diameter. the bosses 23 are of around diameter or thereabouts. The bosses 23 are preferably formed by the projecting reduced-diameter upper end portions of bushings 25 which are received in recesses 26 in the mold cavity bottom 22. The bushings 25 are suitably secured in place in the mold recesses 26, such as by having a press fit therein. The central passageways through the bushings 25 form the nailreceiving apertures 24, and the mold recesses 26 are formed with reduced diameter portions 21 extending downwardly beyond the bushings 25 to thereby accommodate the lower ends of the nails I4 and to also provide positioning shoulders 28 for the bushings. By means of the passageways 21, the bushings 25 may be knocked out of the recesses 26 for replacement purposes. The bosses 23 project above the mold cavity bottom 22 the distance 1%" or so) that the body portion I3 of the clip is to be spaced inwardly from the attachment face II of the lift body III.

The flat underfaces or shoulder surfaces I9 of the upset rivet collars on the nails I4 rest on the flat tops or rims 29 of the mold bosses 23 to thereby properly space and position the clip I2 from the mold cavity botom 22 and prevent tilting of the clip during the molding operation, and also to completely seal or close-01f the bushing apertures 24 from the mold cavity. Preferably, the mold cavity bottom 22 is provided with an additional upstanding center support pin 30 (or more than one such pin especially in the case of larger-sized clips for larger-sized heel lifts) to prevent buckling or downward bending or bowing of the center section of the clip plate portion 53 by the pressure of the molding compound during the molding operation such as would tip or lift and unseat the portions of the nail seating shoulders I9 furthest removed from the center of the clip off the top surfaces of the bushings 25, with resultant disruption of the seal therebetween which would then permit the compressed molding compound in the mold to flow through the separations or gaps between the shoulders I9 and the tops 29 of the bushings 25 and down into the bushing apertures 24 and around the nails I4 therein where it would form stock fiashings in the form of skirts or sleeves on the said nails. The nail-receiving apertures 24 in the bushings '25 are preferably made of slightly larger diameter or size (for instance .008" or so larger diameter) than the nails I 4 so as to permit easy removal of the finished heel lift from the mold. The walls of these apertures 24 serve to center the clip I2 within the mold 20 and prevent lateral shifting of the clip during the molding operation.

In molding the heel lift, shown in Figs. 1-3, the clip I2 is first properly placed in the mold 20 by inserting the nails I4 thereof down into the corresponding mold apertures 24 until the flat annular seating shoulders I9 on the upset portions I6 of the nails engage and rest on the tops or rims 29 of the bosses 23. A quantity of the molding compound is then placed in the mold 20, after which the movable pressure or top plate II of the mold assembly is lowered to close the mold assembly and thereby compress the molding material while the mold is subjected to heat. Due to the fact that the upset collar portions I6 of the clip nails I4 rest against, and are in addition forced against the tops 29 of the mold bosses 23 by the pressure of the molding compound acting on the plate portion I3 of the clip, an effective seal is formed therebetween completely around the nails I4 which thus completely closes off the bushing apertures 24 from the mold cavity 2| and serves to prevent the leakage or flow of the highly compressed molding material down around the shank portions of the nails to form a skirt or flashing thereon. After the required interval of time during which the molding material in the closed mold has been subjected to heat and pressure, the movable top plate 3| is lifted away from the mold 2|] and the finished heel lift then removed from the latter.

The upwardly projecting or boss portions 23 of the bushings 25 produce, in the body portion ID of the finished heel lift, circular recesses 32 forming an annular space, groove or hollow (Figs. 1 and 3) around the base or upset end of the shank of each clip nail M, the said annular groove having a. width of the order of or so, or in other words, an outside diameter (around 1 3'") which is A3" or so greater than the diameter of the nails I4. This annular hollow 32 around each nail I4 provides adequate space into which any stock flashing that may for some reason be formed on the nails, may flow when the heel lift is applied to a shoe heel, thus preventing the gathering or bunching up of such stock flashing between the attachment face II of the lift body I!) and the corresponding surface of the shoe heel such as would otherwise prevent the lift from being completely flattened down against the shoe heel and thereafter remaining thus flattened thereagainst.

nI order to produce, particularly in the case of thin heel lifts, grooves or recesses 32 of the deepest possible depth while maintaining the plate portion I3 of the clip as close as possible to inch or so) from the atachment face II to thereby provide maximum thickness of lift body material on the tread side for wear purposes, the upset rivet collars I6 on the clip nails I4 are made as thin as possible, for instance, of the order of thickness of the plate portion I3 or less, 1. e., from to & inch thick or thereabouts, preferably around A inch. To space the plate portion I3 of such a clip I2 a distance of around or so inwardly from the attachment face II of the lift, the upstanding bosses 23 in the mold cavity 2| should have a height of from 1% to & inch or thereabouts. Such height bosses 23 produce annular grooves or recesses 32 in the lift body It having a depth of the order of 1 s to inch. Grooves or recesses 32 of such an indicated depth and having a width approximating that previously indicated, (i. e., 1 3'"), provide ample space for completely receiving therein any small amount of stock flashing that may for some reason form on the clip nails I4 during the molding of the lift in accordance with the invention. Moreover, any such stock flashing as might thus actually form on the clip nails l4 may, because of the location of its point or origin at a distance inwardly from the attachment face actually terminate wholly within the confines of the recesses 32 so as not to project outwardly beyond the attachment face II and thus present an unsightly appearance or prevent the obtaining of a secure attachment of the lift to a shoe heel.

Fig. 8 illustrates a modification of the invention wherein upstanding bosses 33 of frustoconical shape are employed in the mold 20. Such shaped bosses produce outwardly flaring circular recesses 34 (Fig. 9) in the lift body I0 around the bases of the nails I4, which may be preferable from an appearance standpoint to the cylindrical receses 32 formed by the bosses 23.

Such flaring recesses 34 also provide increased space into which any flashing on the nails I4 may flow during the attachment of the lift to a shoe heel. In addition, the frusto-conical bosses 33 are sturdier than the bosses 23 and thus are better able to withstand the relatively high pressure applied thereto by the clip I2 during the molding operation.

Figs. 10 and 11 illustrate a modification of the invention wherein thin washers 35 of suitable resilient or yieldable material, such as soft rubber for instance, are fitted over the clip nails I4 and abutted against the upset collar portions I6 thereon to thereby form resilient facings or seating surfaces for engagement with the tops 29 of the mold bosses 23. Because of their yieldable character, the resilient washer facings 35 serve to more positively assure and maintain the effective seal-off of the nail-receiving apertures 24 form the mold cavity itself during the molding operation.

As shown in Fig. 10, the effective seal-ofi of the nail-receiving apertures 24 in the mold either by the resilient washers 35 as in Fig. 10, or by the upset collars I6 on the clip nails I4 as in Fig. 6, can be positively assured in any case by providing the pressure or top plate 36 of the mold with a plurality of depending hold-down or pressure pins 31 corresponding in number to and respectively positioned directly over the mold bushings 25. These pins are vertically movable in the pressure plate and are arranged to engage and to be forcefully pressed down or clamped against the rivet heads I! ofthe clip nails by any suitable means (not shown), such as a toggle arrangement for instance, either before or during the lowering of the top plate 36 but in any event prior to any compression of the molding material in the mold cavity, the pressure of the pins serving to forcefully press and hold the resilient washers 35 or the upset collars I6, as the case may be, down tight against the tops of the mold bosses 23. Such depending pressure pins 31 will, of course, leave openings in the tread face of the finished lift which, if not desirable, may be eliminated by resorting to a two-stage molding process such as is used at present in the manufacture of conventional type heel lifts having metal washers molded therein. In this modified method according to the invention, only sufficient molding material (1. e., a portion only of the normal full charge) is initially placed in the mold 20 to eventually imbed just the clip I2 or at least the collars I6 (e. g., up to the dotted line A in Fig. 10), and then a top pressure plate such as is used at present in the first stage of the molding of conventional type lifts having metal washers imbedded therein, but provided in addition with hold-down pins similar to the pins 31 in Fig. 10, is then lowered into the mold cavity 2| to cause the hold-down pins 31 to first engage and forcibly press or clamp down on the nail heads I! and then subsequently compress the molding compound within the mold cavity 2|. The engagement of the hold-down pins 31 of the pressure plate with the nail heads I! of the clip |2 prior to the compression of the molding compound in the mold cavity by the pressure plate, assures the positive seal-off of the nailreceiving apertures 24 from the mold cavity 2| (by the pressure engagement of the resilient washers 35 or the upset collar portions I6 of the nails I4 with the tops 29 of the bosses 23) before the compression of the molding compound in the mold cavity reaches a degree such as would tend to force it through any minute separation or gap between the tops of the bosses 23 and the rubber washers or nail collars l6, and thus down into the bushing apertures 24. Upon completion of this first molding step, the lift is then completed in the same manner as is used at present in the molding of conventional type lifts, i. e., by inserting in the mold cavity 2| an additional quantity of molding compound sufflcient to form the second or final layer of the lift body III and then lowering a conventional type pressure plate 3| (1. e., one without any hold-down pins) to close the mold assembly and from the finished lift body ill. Obviously, instead of using two differently constructed pressure plates for the two molding stages of this modified molding process, a single pressure plate of suitable form may be employed for both steps, in which case the hold-down pins 31 are withdrawn into the plate so as to be flush with the underside thereof during the second stage of the molding process.

In the modification illustrated in Fig. 12, the clip prongs or nails 38 are provided with upset collars 38 of rounded or spherical form, and the mold bosses are provided with cupped or spherical recesses or countersunk sockets 4| in their upper ends concentric with the bushing apertures 24, within which recesses the rounded collars 39 seat to seal and close off the bushing apertures 24 and bosses 40. The rounded collars 39 and seats 4| function in the manner of a ball and socket connection to allow the rounded collars to rock in the cupped seats and thus assure an effective seal or closing-off of the bushing apertures 24 from the mold cavity 2| at all times during the molding operation despite any slight tilting of the clip plate 13 at the bosses 40 which might result from the downward bending or bowing of the clip plate by the pressure of the molding compound thereagainst during the molding operation. Such downward bending and resultant tilting of the clip plate I3 is limited to a very small degree, moreover, by the upstanding center pin 30, which is preferably provided in the mold cavity 2| for such purpose, and the ball and socket clip-supporting arrangement 39, 4| shown will effectively maintain, without difficulty, the seal-off of the bushing apertures 24 within such a limited range of tilting movement of the clip plate 13. The annular grooves or recesses 42 (Fig. 13) formed in the lift body I0 by the modified arrangement of Fig. 12 extend inwardly substantially to the plate portion l3 of the clips and, like the recesses 32, are of ample size to accommodate therein any stock flashing that may by chance be formed on the clip nails 38. If desired, the use of hold-down pins 31 in the pressure plate of the mold, such as shown in Fig. 10, may be utilized with the modified clip and mold arrangement of Fig. 12.

The attachment of the heel lift, shown in Figs. l-3, to the heel of a shoe can be performed in a very simple, quick and convenient manner, i. e., merely by striking one or two hard and welldirected hammer blows against the lift, over the region of the clip l2 therein, while the lift is held in place on the shoe heel. The hammer blows drive the clip prongs or nails l4 into the shoe heel and at the same time flatten the arched lift body 10 down against the shoe heel. Due to the absence of nail apertures in its exposed or tread face, the heel lift, shown in Figs. 1-3, presents an extremely well-finished appearance when thus fastened in place on a shoe. Moreover, because of the particular construction of the clips l2 wherein the .plate portion 13 extends over and beyond the nails II, the force of the hammer blows is directed more or less straight down through the nails, thus eliminating any splitting of the shoe heel in those cases where it is made of wood. The lift body It being made of relatively stiff heel composition, the clip 12 will effectively fasten the lift in place on the shoe heel so as not to separate therefrom around its edges.

The molding of the heel lift, in accordance with my invention, is much simpler and cheaper than the molding procedure required to manufacture heel lifts of the conventional type having nail apertures therethrough and metal washers embedded therein. In molding such conventional type heel lifts, a thin layer of molding compound is first pressed in the mold, after which the metal washers are placed on top this first layer and a second layer of molding compound then molded on top of the first layer. With the heel lift, shown in Figs. l-3, however, it is merely necessary to place the clip l2 in the empty mold, after which the molding of the entire lift body I0 can then be performed by a single molding operation.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A mold for molding a heel lift with a fastening clip insert comprising a thin plate portion and a plurality of spaced parallel prongs projecting perpendicularly from one side of said plate portion, the said clip further having annular seating surfaces surrounding respective prongs at their base ends, said mold comprising a body portion having a mold cavity the side walls of which conform to the configuration of the lift edges, a plurality of spaced bosses upstanding from the bottom of the mold cavity and provided with apertures for receiving the clip prongs, the tops of said bosses comprising annular seating surfaces corresponding to the seating surfaces on the clip and on which the latter seat to position the clip in the mold and close off the boss apertures from the mold cavity, and a pressure plate movable against the said mold body to close the mold, said pressure plate having a plurality of hold-down pins therein corresponding to and aligned with the said bosses of the mold body and longitudinally movable in said pressure plate for clamping against the upper side of the fastening clip in the mold prior to complete closure of the mold.

2. A mold for molding a heel lift with a fastening clip insert comprising a thin plate portion and a plurality of spaced parallel prongs projecting perpendicularly from one side of said plate portion, the said clip further having rounded annular seating shoulders at the underside of the plate portion at the base ends of and surrounding respective clip prongs, said mold comprising a body portion having a mold cavity the side walls of which conform to the configuration of the left edges, and a plurality of bosses upstanding from the bottom of the mold cavity and provided with apertures for receiving the prongs, the tops of said bosses being formed with cupshaped sockets concentric with the apertures in the bosses and in which the said rounded seating shoulders of the clip seat to thereby close of! the said apertures from the mold cavity.

3. The method of molding an article having embedded therein a fastening clip comprising a, plurality of prongs and continuous annular seat portions located at the bases of and concentrio with the said prongs which method comprises, positioning the clip within the mold cavity with the clip prongs received within apertures in the mold bottom and with the annular seat portions of the clip seated against and completely around the rims of the said apertures to thereby close off the apertures from the mold cavity, clamping the said annular seat portions of the clip tightly down against the said rims of the apertures in the mold bottom, introducing into the mold cavity a partial charge of molding material sufficient to completely imbed, when molded, the annular seat portions of the clip, subjecting the said partial charge of molding material to heat and pressure, while maintaining the said seat portions clamped tightly down against the said rims of the said mold apertures, to thus completely imbed the said seat portions of the clip, opening the mold and introducing into the mold cavity the remainder of the full charge of molding material for the lift, and then subjecting the said remainder of the charge of molding material to heat and pressure without clamping the said seat portions down against the said rims of the mold apertures.

4. The method of molding an article having embedded therein a fastening clip comprising a plurality of prongs and continuous annular seat portions located at the bases of and concentric with the said prongs which method comprises, inserting over each of said prongs and seating against the said seat portions a washer of yieldable material, positioning the clip within the mold cavity with the clip prongs received within apertures in the mold bottom and with the yieldable washers on said prongs seated against and completely around the rims of the said apertures to thereby close off the apertures from the mold cavity, introducing a charge of molding material into the mold cavity, and then subjecting the said charge of molding material to pressure and heat.

5. A mold for molding a heel lift with a fastening clip insert comprising a thin plate portion having a plurality of spaced parallel prongs projecting perpendicularly from one side thereof and having spherically shaped seating shoulders at the underside of the plate portion at the base ends of and surrounding respective clip prongs, said mold comprising a body portion having a 1o mold cavity the side walls of which conform to the configuration of the lift edges, a plurality of bosses upstanding from the bottom of the mold cavity and provided with apertures for receiving the prongs, the tops of said bosses being formed with spherically shaped sockets concentric with the apertures in the bosses and in which the said.

spherically shaped seating shoulders of the clip seat to thereby close off the said apertures from the mold cavity, and supplementary support means upstanding from the bottom of the mold cavity within the region thereof bounded by said bosses for engagement with the plate portion of the clip to prevent buckling thereof during the molding operation.

6. A mold for molding a heel lift with a fastening clip insert comprising a thin plate portion and a plurality of spaced parallel prongs projecting perpendicularly from one side of said plate portion, the said clip further having annular seating surfaces surrounding respective prongs at their base ends, said mold comprising a body portion having a mold cavity, a plurality of spaced bosses upstanding from the bottom of the mold cavity and provided with apertures for receiving the clip prongs, the tops of said bosses comprising annular seating surfaces corresponding to the seating surfaces on the clip and on which the latter seat to position the clip in the mold and close off the boss apertures from the mold cavity, and a pressure plate movable against the said mold body to close the mold, said pressure plate having hold-down means vertically movable therein to clamp down against the upper r side of the fastening clip in the mold prior to complete closure of the mold.

ANTHONY A. RIZZO'.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Re. 14,596 Hooper Feb. 25, 1919 222,229 Beals et al Dec. 2, 1879 1,273,047 Ellithorpe July 16, 1918 1,693,409 Southmayd Nov. 27, 1928 1,974,219 Shank Sept. 18, 1934 2,027,651 Penardi Jan. 14, 1936 2,341,364 Crumrine Feb. 8, 1944 2,356,585 Hempel Aug. 22, 1944

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