US3530489A - Footwear manufacture - Google Patents

Description

Sept. 22, 1970 D. APPLETON 3,530,489

FOOTWEAR MANUFACTURE Filed Aug. 19, 1968 5 Sheets-Sheet 1 In men for Dan 21?? A ppleto/z 55/ his A tar/26y miw Sept. 22, 1970 APPLETON 3,530,489

FOOTWEAR MANUFACTURE Filed Aug. 19, 1968 3 Sl1wts-$huet .J

p 22, 1970 D. APPLETON FOOTWEAR MANUFACTURE 3 Slums-Sheet 5 Filed Aug. 19, 1968 3,530,489 FQOTWEAR MANUFACTURE Daniel Appleton, Topsfield, Mass., assignor to USM Corporation, Flemington, N.J., a corporation of New Jerse y Filed Aug. 19, 1968, Ser. No. 753,598

Int. Cl. A43b 13/38 US. Cl. 36-44 4 Claims ABSTRACT OF THE DISCLOSURE The present invention is directed to a cushion insole unit of particular laminate construction. Specifically, a flexible polyurethane foam interliner is laminated with an extensible, permeable top sheet and a dimensionally stable bottom sheet.

The present invention relates to footwear and particularly cushion insole units.

Cushion insole units are being used in increasing numbers by the shoe industry. The increase would be considerably greater, however, if they could be constructed so as to contribute the various aspects necessary to foot comfort as well as having durable construction. The improvement in one aspect of foot comfort has generally brought sacrifice in another, or adversely affected the strength or wear life of the unit. This latter has been particularly a concern where the unit is the built-in type, that is, it is designed to be included in the footwear assembly, shoe, etc. during its manufacture on the last, form, etc.

The foot comfort aspects which are desirable to have in an insole unit include the following. First, the unit should provide cushioning for the foot which includes the ability to deform or be depressed under the load of the wearers weight on a curve function basis to an extent less than complete bottoming and with minimum horizontal displacement of the cushion or cushioning material. Load distribution enters here, and, parenthetically, to facilitate that somewhat, cushion insoles have been provided with critical contours, based primarily on the thickness of the cushioning to be provided under various points or parts of the foot. To return, as part of cushioning the unit should be able to recover quickly from the deformed or depressed state once the load is removed, as happens in fairly quick intervals with walking. In this latter regard too, it is desirable for the unit to retain a slight orientation to the particular wearers foot. The second aspect relates to the vapor transmission quality of the unit. In order to maintain the wearers foot in relatively dry state, the unit should have the ability to absorb or accept perspiration. The vapor transmission quality then should be such to allow passage of perspiration vapor inwardly during wearing, and in some lesser degree outwardly when the unit is not being worn.

From a construction standpoint insole units are subjected to continual flex with wear. This is aggravated in the case of the cushion types because of their construction and bulk which contribute further distortive qualities under load. This situation then is particularly critical when the units are of laminated construction as is usual; and it is to this type construction that the present invention directs its attention. With cushion insole units of laminated construction not only are there problems of cracking and deterioration, but also those of serious delamination between the various parts at their lamination sites.

It is an object of this invention to provide improved cushion insole units, of laminate type construction, exhibiting improvements in comfort aspects and construction.

It is another object of this invention to provide imnited States Patent proved cushion insole units of laminate type construction exhibiting increased wear life due to increased resistance to cracking, deterioration and particularly delamination of parts.

It is another object of this invention to provide an improved method by which to produce cushion insole units of laminated type construction in turn exhibiting improvement in comfort aspects and construction.

The objects set forth above are attained in a particular cushion insole unit, and method of producing the same.

The subject insole unit comprises an interliner of open pore, flexible polyurethane foam interposing in direct laminated coextensive relationship an extensible, flexible, permeable top sheet and an essentially nonextensible bottom sheet having at least an interrupted upper surface portion.

The laminating method of the present invention involves first positioning the extensible permeable top sheet and the essentially nonextensible bottom sheet in spaced relationship one with respect to the other within a molding site. A foamable, reactant, urethane composition in liquid or fluid form is then introduced into the space formed between the sheets, and the indicated relationship is maintained between the parts while the urethane composition sets to a solidified, flexible open pore polyurethane foam interposing and bonding to both sheets and more specifically to the inwardly directed or opposing faces of the sheets.

As indicated previously the cushion insoles presently known are generally laminated construction. The usual practice carried out in producing them involves first providing the various preformed parts, usually cover sheets and a foam, cork or other flexible cushioning unit. These parts are then provided with a quantity of adhesive at the surfaces contemplated to form interfaces. After assembly of the adhesive carrying parts in the desired manner they are maintained as such, usually under pressure until the adhesive sets up to bond the various parts together into a laminated insole material or unit.

A number of shortcomings are attendant with that type of construction. They can be attributed to a large extent to the dependence and presence of the adhesive. It can interfere with obtaining contouring of the various parts in assembly; act as a barrier or barriers to vapor transmission; and provide a situs of potential weakness at which delamination takes place.

By contrast the cushion insole unit of the present invention does not rely on an adhesive to laminate or consolidate the various parts. As a result it suffers from none of the above enumerated shortcomings.

The top sheet of the subject insole is flexible and permeable and at least essentially extensible in nature. It is extensible to the extent that it may conform with the deformation or into the deformation pattern introduced into the cushion with wear. It is permeable to allow vapor transmission and where bonding of a physical nature is relied on sites at which the bonding with the interliner polyurethane foam material takes place. Top sheets which are porous in nature and having thicknesses ranging 5 to 20 mils are preferred. A number of materials may be used for the purpose. They include porous sheets, films, castings or coatings such as those of polyvinyl chloride homopolymers and copolymers (vinyl chloride-vinyl acetate; vinyl chloride-vinyl alcohol, etc. copolymers), polyester urethanes, synthetic rubber, etc. and preferably the polyvinyl chlorides which are in blown and crushed; leached or sintered form or sprayed onto and deposited on the mold cover or polyurethane interliner prior to curing or set up of the latter, to provide porosity. Also included are the hydrophilic polyurethane sheets, castings or coatings. In addition to films or coatings it is also possible to use woven and nonwoven fabrics of an extensible nature as well as certain natural sheet materials, A preferred sheet material is a blown, crushed polyvinyl chloride film which is porous in nature.

The bottom sheet is essentially nonextensible While nonetheless being flexible in nature. The former property contributes dimensional stability, i.e. considered primarily from a surface area and configuration basis, which in turn contributes better cushioning support and distribution of the load throughout the cushion interliner. It also insures against the shoe becoming misshapen. Thus the bottom sheet is designed to contribute foundation or structure to the insole. At least the upper surface portion of the bottom sheet is interrupted or noncontinuous in nature, either from a physical or chemical standpoint. The entire thickness of the sheet may be similarly constructed. To return, to be interrupted then the upper surface portion of the bottom sheet may be porous, roughened, leached, primed or the like to provide a bonding surface for the polyurethane on forming the interliner. Materials which serve well as bottom sheets are the various fiber or composition insole boards which are porous in nature. Other materials which may be used include leather, foamed polyvinyl chlorides, synthetic rubbers or polyurethanes. In the case of open foams disruption is already present. In the case of closed cell foams disruption is created as indicated by roughening, leaching, priming, etc. With choice, the bottom sheet may serve as the outsole for footwear, or a shoe including the insole unit provided, of course, it is included into the same during manufacture of the footwear or shoe. In this latter regard the insole used may be included during manufacture, that is, on the last or form and a shoe built from it, or, it may be post-inserted into an otherwise completed shoe.

The polyurethane interliner is based on a particular class of polyurethanes. These are flexible open cell polyurethanes having a density of 0.2 to 0.6 gin/cc. and preferably 0.2 to .3 gm./cc.

In producing the polyurethane of the interliner, a trihydric polyol, more specifically, a polyester or polyether having trihydric functionality, having an equivalent weight of about 900 to 1300' is reacted with 2l5 percent stoichiometric excess of diisocyanate in the presence of 0.5 to 2.5 weight percent of a particular catalyst system, a surfactant and a blowing agent.

The polyesters and polyethers which may be used in producing the polyurethane interliner material of the subject footwear units have trihydric functionality, that is, they contain three hydroxyl groups each. In addition they have about 900 to 1300 equivalent weight or molecular weights ranging about 2600 to 4000. Examples of these include polyethers which are based on polypropylene oxide run outs of glycerol, trimethylolpropane, 1,2,6 hexane triol, etc.; polyesters which are condensation products of glycerol with a glycol and dibasic acid such-as adipic acid, as well as various vinyl graft copolymers of those materials. Various blends of the trihydric esters and ethers may be used. Blends which operate Well are those which combine with the trihydric type, various lesser amounts of dihydric esters and ethers having molecular Weights ranging from about 1800 to 2600 or equivalent weight ranging from about 900 to 1300.

The diisocyanates for use include methylene diisocyanate, toluene diisocyanate, and the various isomeric mixtures of the same. As indicated, a stoichiometric excess of the diisocyanate is used. This is 2-15 percent stoichiometric excess with a more preferred range being 3 to 7 percent stoichiometric excess. When the polyurethane is the water blown type the excess is calculated based on the amount of water used added to the ester and/or ether. This is for the reason that water includes hydric functionality.

The particular catalyst used is a mixture of an amine catalyst with tin catalyst. Amines for use include diethylene triamine, triethylene diamine, tetramethyl butane diamine, N-methyl morpholine, N-ethyl morpholine, bis

4. (dimethylamino) ethyl ether, etc. Tin catalysts for use in the mixed catalyst system are exemplified by stannous octoate and dibutyl tin dilaurate. The amount of mixed catalyst used ranges 0.5 to 2.5 weight percent based on total Weight of reactants. The ratio of amine catalyst to tin catalyst ranges about 1:2 to 1:4 on a Weight basis respectively With the preferred range being about 1:3.

The surfactant or cell structure preservative for use may be any of those available for use in producing flexible polyurethane foamed polymers. These include polyoxypropylene-polyoxyethylene copolymers, nonylphenolethylene oxide adducts, alkoxy silanes, polysilyphosphonates, polydimethyl siloxanes and polydimethyl silox ane-polyoxyalkylene block copolymers. While all may be used, it is recommended in the case of polyether based urethane foams that either the polydimethyl siloxane or polydimethyl siloxane-polyoxyalkylene block copolymers be used. The latter two may be referred to as polyalkane silicones, and are preferred. The amount of surfactant recommended ranges about 0.5 to 2.0 by Weight based on the total weight of the reaction medium.

The blowing or foaming agents which may be used include the various fluorocarbons, methylene chloride, Water, etc.

In preparing the polyurethane interliner, in situ, a one shot reaction procedure is followed. This has reference to the fact that the diisocyanate is introduced to the final reaction in previously unreacted condition. The final reaction is that which directly produces the polyurethane as a solidified, open cell flexible foam. The one shot reaction procedure distinguishes from those situations where the diisocyanate is first partially reacted to produce a prepolymer, which is then further or finally reacted to produce the solidified product.

In practicing the one shot reaction procedure, the various reactants are admixed to produce a liquid reactant mass which is then charged in a predetermined amount into a space provided or defined between the upper and lower sheet positioned in a mold or molding site. The foaming-solidification reaction is then carried out there, in situ. The viscosity of the reaction mass is established at about 500 to 3500 centipoises, with a more preferred range being about 1000 to 2000 centipoises. To facilitate the reaction a mold temperature of F. to 200 F. and preferably F. to 180 F. is used. In addition the mold or molds used are the closed type.

The following example is provided for the purpose of illustrating the invention.

EXAMPLE I (A) Preparation of liquid foamable urethane composition The following general formulation is mixed together in a low shear mixer:

Material: Amount (p.p.w.) Polyol (1200 eq. wgt.) 60.0

Triethylene amine 0.2 Bis dimethylamino ethyl ether 0.1 Dibutyl tin dilaurate 1.0

Water 0.63 Dimethylpolysiloxane polyethylene polypropylene oxide (surfactant) 0.6

Specific compositions are based on various polyols used. These include (1) polyoxypropylene glycol runout of glycerol (triol) having a molecular weight of 3600, (2) polyethylene adipate runout (triol) of glycerol having a molecular weight of 3700, (3) vinyl graft copolymer of polyoxypropylene runout of glycerol (triol) having a molecular weight of 3600 and (4) a blend of polyoxypropylene runout of glycerol (triol) having a molecular weight of 3600 and polyoxypropylene glycol (diol) having a molecular weight of 2000 in a ratio of 1:1 by equivalents, respectively,

Immediate to molding, 100 parts by weight of liquid methylene diphenyl diisocyanate is mixed with 350 parts by weight of the resin mixture above.

The liquid foamable urethane compositions so prepared have viscosities of about 1500 to 2000 centipoises (B) Molding flexible cushion footwear units A molding machine is used together with a number of metal molds providing molding cavities of different sizes, outline and depth, in order to produce units for use in sizes 8 and 9 mens shoes and size 7 womens oxford shoes. The different depths of the cavities in the mold bodies facilitate production of units having bottom sheets of different thicknesses while nevertheless providing or producing footwear units including cushion interliners with contours based on 0.125 inch forepart thickness, 0.375 inch arch thickness and 0.250 inch heel thickness. The mold bodies have vacuum holes located at the bottom of the same and are provided with electrical contact heaters.

A bottom sheet is placed into a mold cavity and positioned securely by vacuum applied to the same. The bottom sheets include those ranging 25O mils in thickness, more specifically, sheets of Texon which is a copolymer latex impregnated cellulosic matrix having a thickness of 3.5 iron; cotton linter sheet having a thick ness of 3.5 iron; leather having a thickness of 250 mils; and microcellular rubber and urethane elastomeric foam each having a thickness of 250 mils.

A shot of the urethane composition prepared as above is introduced into a mold cavity by pouring into the upper surface of the bottom sheet. In the case of the size 9 shoes the shot is 35 grams, the size 8, 30 grams and the size 7, 25 grams.

The top sheet is positioned over the top of the urethane composition by either of two techniques. In the first a flexible permeable sheet 12 mils in thickness is stretched over the mold cavity. The top sheet so used is blown crushed polyvinyl chloride sheet; sintered polyvinyl chloride sheet or leather. The second technique involves providing an acrylic copolymer latex in emulsion form into the mold cover sufficient to produce on solidification a permeable coating 12 mils in thickness. In each technique then the mold cavity is closed by positioning the mold cover over the same. The mold cavity is clamped down to minimize flash. The mold is heated to a temperature of 140 F.-l80 F. After an in-rnold period of 60 to 300 second, depending upon the particular situation involved, the mold is opened and the footwear units so produced are removed from the cavity.

(C) Polyurethane interliner testing A number of units produced as above are cut through lengthwise. It is observed that continuous, well bonded interfaces have been obtained between the various parts making up each of the units. Sample pieces of the flexible polyurethane forming the cushion interliners are cut away and tested with the following mean testing results.

(1) Compressiondeflection 25%2.0 to 5.0 p.s.i.

(2) Compression set--5.0 to 20.0 percent (3) Moisture vapor permeability-2.5 to 3.5 gm. mils/ sq.

meter/ day (4) Cells-50400 per linear inch A number of pairs of welt shoes are constructed. In the major instance the units produced according to paragraph B above are included, by assembly, during manufacture. A small number are post-inserted in shoes.

The shoe sizes include sizes 8 and 9 in mens shoes and size 7 nurses oxfords.

The shoes are then sent out for wear testing. The numbers involved include 150 pairs of the size 8 type worn by boys in a correctional institution, of these 6 pairs have post-inserted type units; 12 pairs of the size 9 type worn by technical staff members; and 12 pair of size 7 nurses oxfords worn by nurses. All except those specifically mentioned as otherwise, include the units inserted during manufacture.

The test period is three months in duration. On return, insole units are removed from the shoes and are slit down the middle and inspected to observe whether (1) any delamination is evidenced, (2) orientation to foot shape (compression set), (3) any breakdown evidenced in the cell structure of polyurethane interliners.

In all instances the units indicate excellent performance based on the fact that no delamination is evidenced between parts. In addition to that there is orientation to the foot shape evidenced, Without full bottoming having taken place, and the cell structures of the interliners show no evidence of breakdown.

The individuals wearing the shoes for testing purposes are interviewed or provide written reports on the comfort aspects of the test shoes. All aspects are reported favorably, with the exception that some wearers indicate that the shoes seem to build up more heat than is evidenced in shoes not including the unit of the present invention. On the other hand, none complain about moisture or sweat accumulation on the upper surface of the unit. Accordingly, the heat build up may be attributed to the frictional characteristics of top surface skin.

The following drawings are included for the purpose of illustrating the invention in which:

FIG. 1 is a perspective view, partially broken away, of one embodiment of the cushion insole unit of the present invention;

FIG. 2 is a perspective view, partially broken away of a second embodiment of the cushion insole unit of the present invention;

FIG. 3 is a partial magnified view in side elevation of the structure of the cushion insole unit of the present invention, particularly as it refers to the embodiment of FIG. 1;

FIG. 4 is a partial magnified view in side elevation of the cushion insole unit of the present invention, particularly as it refers to the embodiment of FIG. 2;

FIG. 5 is a perspective view of a sandal which includes the embodiment of the cushion insole unit of FIG. 2;

FIG. 6 is a perspective view, with parts broken, of a casting machine for producing the cushion insole unit of the present invention, in the filling position;

FIG. 7 is a perspective view, with parts broken, of that part of the casting machine of FIG. 6, showing it in the top sheet positioning position; and

FIG. 8 is a perspective view, similar to that of FIG. 7 showing the casting machine in the closed position.

Reference is now made to the drawings. As shown in the embodiment in FIG. 1, the cushion insole unit 10 of the present invention includes an interliner 12 of flexible, open cell polyurethane having a density in the range of 0.2-0.6 gm./cc. The interliner 12 is directly laminated in coextensive relationship to an extensible permeable and flexible top sheet 14 of blown, crushed polyvinyl chloride. An essentially nonextensible bottom sheet 16 is similarly directly laminated in coextensive relationship to interliner 12. As shown the bottom sheet 16 is constructed of insole board.

The insole unit 10 shown in FIG. 1, is of the contoured type and is designed for post-insertion into a shoe, not shown. The contour which may be conveniently introduced into the insole 10 by practice of the present invention complements to a large extent that of the bottom of the wearers foot, not shown. This comfort aspect is further increased by practice of the present invention with reliance on a particular polyurethane from which to produce the interliner 12.

The insole unit embodiment 20 of the present invention has the same basic laminated construction as does the insole unit embodiment 10. Insole 20 is constituted of an interliner 22 of flexible, open cell polyurethane interposed through direct, coextensive lamination by a top sheet 24 which is permeable and flexible; and a bot-- tom sheet 2 6. The latter is constructed of leather having the thickness and flexibility usual for leather outsoles. While the insole 20 is cushioned, and contoured it is further adapted for inclusion during manufacture, by having a shoe part attaching margin 28. In the embodiment under discussion, the top sheet 24 is laminated directly to the bottom sheet 26 at the margin portion 28. This is done primarily to make a more attractive unit as there is no necessity to extend the top sheet 26 over the margin 30. In this regard, however, it is recommended that the margin 28 not include a portion of interliner 22 which would interfere with stitching, sewing or other similar shoe production operation.

Specific aspects of the insole of the present invention are shown in FIGS. 3 and 4 which correspond respectively to the embodiments shown in FIGS. 1 and 2.

As shown in FIG. 3 the insole 10 includes an interliner 12 constituted of open-pore, polyurethane foam. Pores 30 and consequently porosity continues through the interliner 12. The uniformity of the porosity, developed from use of the particular urethane, contributes improved cushioning, distribution of weight, and vapor transmission or push up by the interliner 12. The top sheet 14 is in direct laminated coextensive relationship with the interliner 12. The top sheet 14 is shown including a number of pores 32, which provide vapor transfer into the interliner 12. The top sheet 14 is of blown and crushed polyvinyl chloride. At the interfacial portion 34 formed between the interliner 12 and the top sheet 14 there is intermingling of the two materials involved but to the extent that not all the pores 30 and 32 are blocked. This allows for excellent and strong lamination attachment through inter-anchoring of the materials, polyurethane and polyvinyl chloride, to take place between parts, while nevertheless retaining porosity and vapor transmission qualities at the interfacial portion 34. The amount of intermingling vs. porosity retention achieved may be determined to large extent by choice of top sheet material, original porosity of the same, and the pressure exterted downwardly on the same during casting of the polyurethane foam interliner in situ as well as the relative size of the polyurethane casting charge. Similarly, there is an interfacial portion 36 located between the interliner 12 and the bottom sheet 16, which former is more specifically an interrupted surface portion 36 of the bottom sheet 16. At interfacial portion 36 lamination or attachment is the main concern. Porosit provided there if at all is incidental. Because of the relative stilfness of the bottom sheet 16, it is necessary to achieve strong lamination between the same and the interliner 12. Providing the bottom sheet 16 with an interrupted surface 36 at which attachment takes place on casting of the polyurethane interliner in situ, facilitates that.

The embodiment of FIG. 4 corresponds to that of FIG. 2. The insole 20 includes an interliner 22 containing a. plurality of interconnecting pores 40, formed of opencell flexible polyurethane. Similarly the top sheet 24 includes a plurality of pores 42, providing vapor transmission through the top sheet 24. An interfacial portion 44 interposes and serves as a permeable anchoring or lamination situs or includes a number of such sites between those parts. An interfacial portion 46 is formed between the interliner 22 and the bottom sheet 26. This serves as an attachment situs between those two parts, and more particularly as relates to the bottom sheet 26, as an interrupted top portion 46 of the same. The bottom sheet 26 in this case is constructed of leather, such that it may serve an outsoling function.

FIG. shows a simplified utilization of the insole unit 20. There a shoe and more specifically a simplified sandal 50 which includes the insole unit 20, has an integral outsole serving as the bottom sheet 26. The upper 52 is assembled from a forepart 54 and a backpart 56 consolidated through a strap 58. The upper 52 is attached to 8 the insole 20 by stitching down the side leading edges 60 and 62 respectively of the forepart 54 and the backpart 56 onto the margin portion 28 of the insole unit 20. The insole unit 20 is adapted to be included during manufacture of shoes other than sandals.

The method for producing the cushion insoles of the present invention may be described relative to a casting machine shown in FIGS. 68. The casting machine is two station in nature, a charging and incidentally discharging station and a casting station. A frame constituting side rails 72 and 74 and end rails 76 and 78 of welded construction is located on dependent sup-ports 80. The side rails 72 and 74 serve to slidably support a mold block 82 while the end rails serve also as stops to limit the horizontal positioning of the mold block 82.

The mold block 82 defines a mold cavity 84, having vacuum positioning holes (not shown). These serve to locate or draw a precut bottom sheet 16 at or against the bottom surface (not shown) of the cavity 84. The mold block 82 includes ends 86 and 88, sides 91) and 92 as well as the top surface 94 in which mold cavity 84 and a number of positioning pin holes 95 are located. Each of sides 90 and 92 include a pair of slots. The first of these, 96 and 98, serve to locate the mold block 82 relative to the rails 72 and 74 respectively. The second pair, stabilizing slots 100 and 102, cooperate with a key 104 supported on a flange 106 when the mold block 82 is positioned at the casting station. A second corresponding key and flange combination is not shown. The mold block 82 is further provided with an electrical power conduit 108 connecting a mold heater with a power source, neither of which is shown. Additionally, to provide the vacuum mentioned previously, a vacuum line 110 connects to a vacuum pump, not shown.

In order to direct a foamable polyurethane charge 112 into the mold cavity 84, a suitable dispenser 114 is suspended above where the cavity 84 will be located when at the designated charging station. The dispenser includes a nozzle 116 having a cut off 118, leading from a mixing head 120 where the one shot foamable polyurethane is mixed. The foamable polyurethane ingredients are led into mixing head 120 through charging lines 122 and 124 from material sources, not shown.

The casting machine 70 is provided with means for providing a top sheet 14 and for closing 011 the mold cavity 84 both of which are located at a position above where the latter will be located when at the designated casting station.

To provide top sheet 14, an upright support member 126 supports a sheet supply roll 128 and a guide roll 130, and a drawing roll, not shown, directs the sheet 14 between a pair of frame members 132 and 134 of matching size and shape. The frame members 132 and 134 are adapted to be clamped together and securely hold the sheet 14 therebetween. This is effected through a pair of generally inwardly facing, inverse L-shaped flange members 136 and 138 somewhat diagonally located with respect to each other secured to each side of the bottom frame member 134. Hydraulic pistons 140 and 142 are located above the flange members 136 and 133. The pistons 140 and 142 have positionable piston rods 144 and 146 which project through holes provided in the flange members 136 and 138, and threaded into top frame member 132. With actuation of the pistons 140 and 142 the piston rods 144 and 146 and driven downwardly forcing the top frame member 132 downwardly against bottom frame member 134.

A second pair of hydraulic motors 148 and 150 operate to clamp the closed frame members 132 and 134 over the mold block 82 when the latter is positioned at the casting station. In doing so piston rods 152 and 154 threaded into receiver plates 156, 158, secured to top frame member 132 are driven downwardly to lower the assembly. The re ceiver plates 156 and 158 are slidable on guide rods 160 and 162.

A movable mold cover 164 carrying a number of positioning pins 166 is generally positioned above the frame members 132 and 134. The cover 164 has a shape and size which allows it to fit inside the frame members 132 and 134. A plate 167 is attached to the top surface 168 of the cover 164, and to the piston rod 170 of a hydraulic piston. A receiving plate 174 is attached to the top surface 168 and a cover balancing plunger 176 is adapted to contact the plate 174. The latter serves to facilitate tight positioning of mold cover 164 relative to mold block 82, similarly secure closing off of mold cavity 84. As a result the sheet 14 is tightly positioned with respect to the mold cavity 84, thereby facilitating improved lamination or attachment between sheet 14 and the cushion interliner 12 which is produced in situ. It also serves to minimize production of flash.

One method of producing the cushion insole units of the present invention may be described with reference to FIGS. 68 taken in that sequence.

As indicated in FIG. 6, the mold block 82 is located at a charging station, where the bottom sheet 16 is located within the mold cavity 84. Vacuum introduced through the line 110 facilitates that location. A material charge of foamable polyurethane 112 is then introduced into the cavity 84, and distributed there if so desired. Similarly a length of the top sheet 14 is drawn off the supply 128, directed over the guide roll 130 and between the frame members 132 and 134.

The charged mold block 82 is then slid along the rails 72 and 74 to the casting station, where, as shown in FIG. 7, it is positioned below the frame members 132 and 134, which are registered together with the top sheet 14 secured between them.

Thereafter, as indicated in FIG. 8, the frame members 132 and 134 are lowered in registration over mold block 82. Then, the mold cover 164 is moved downwardly inside at least the upper frame member 132 and with sheet 14 interposed, positions on the mold block 82. This serves to position the sheet 14 over mold cavity 84 and to close the mold cavity 84 at the same time. At this point heating of the mold block 82 is effected by electrical power directed through the conduit 1 08. As a result the foam able polyurethane charge 112 reacts and sets up in situ to an open-pore, flexible foam which laminates in coextensible relationship to the top sheet 14 and the bottom sheet 16.

Thereafter, the mold cover 164 is raised. The frame members 132 and 134 are raised and the cushion insole unit 10 is removed from the cavity 84 and the top sheet 14 trimmed. The result is an insole 10 as shown in FIG. 1.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efiiciently attained and, since certain changes may be made in the above cushion insole without departing from the socpe of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having thus described my invention what I claim as new and desire to secure by Letters Patent of the United States is:

1. An improved cushion insole unit comprising an interliner of open pore polyurethane foam interposed in direct laminated coextensive relationship between a top sheet of crushed polyvinyl chloride foam and an essentially nonextensible bottom sheet having an interrupted upper surface portion.

2. An improved cushion insole according to claim 1 wherein the bottom sheet is leather.

3. An improved cushion insole according to claim 1 wherein the bottom sheet is formed of polyvinyl chloride foam.

4. An improved cushion insole unit according to claim 1 wherein the bottom sheet is fiberboard.

References Cited UNITED STATES PATENTS 2,642,677 6/1953 Yates 36-1 1.5 2,724,913 11/ 1955 Russell 36-11.5 2,757,461 8/ 1956 Cartwell.

2,784,502. 3/1957 Morali 36-44 3,126,650 3/1964 Goldstein 36-44 X 3,143,812 8/1964 Bittner 36-44 3,323,233 6/1967 Scholl 36-11.5 3,398,469 8/1968 Bressan 36-44 X FOREIGN PATENTS 1,083,23 8 9/ 1967 Great Britain.

ALFRED R. GUEST, Primary Examiner

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