US 2607061 A
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J. F. LEAHY ET AL METHOD OF ATTACHING HEELS TO SHO Aug. 19, 1952 Filed Dec.
3 Sheets-Sheet 1 I rwentons James F Leahy John W Ashley By METHOD OF' ATTACHING HEELS TO SHOES Filed Deo. 28, 1949 3 Sheets-Sheet 2 Innen/tons Jmes F.' Leahy John W Ashley Aug. 19, 1952 J. F. LEM-wv ET AL METHOD OF ATTACHING HEELS TO SHOES 3 Sheets-Sheet S5 Filed Dec. 28, 1949 Inventors James Il-'Leahy u Jol-m. W Ashley Patented Aug. 19, 1952 UNITED STATES ,PATENTE orties) j .f 4 c y 2,607,061 ,jw v METOD OF ATTACHING HEELS TOSHO-ES v .lames Leahy and John Ashley, Beverly,
Mass., assignors to United Shoe Machinery Corporation, Flemington, l.Ilfa corporation of New Jersey Application December 28, 1h49, Serial No. 135,352
This invention relates to the manufacture of shoes and is herein illustrated with reference to amethod of attaching heels to shoes by the use .of thermoplastic resin.
It has. been proposed. as disclosed. for eiiample in United States Letters Patent VNo,v 2,447,5l2, granted August 24, 1,948, on an application filed the. name of James. E?. Leahy,l permanently to attach a heel to a shoeby thermoplastic resin which is injected into opposite. undercut cavities Y No. 2,600,507., granted on June 17, 1952 on an ap- Yplicationiiled in our. namesA of which applica.- rtion the present application is a. continuation, in
part, in the attachment of. wood heels to shoes in accordance with the above practice the heel of the shoe is clamped with heavy molding pressure against the heel seat of the shoe and softened thermoplastic resin is thereafter injected under high substantially sustained pressure through a passage extending heightwise, of the heel and terminating at the tread end of the heel into the above-mentioned undercut cavities and voids. It will be vappreciated that the amount of pressure which in the attachment of the wood heel to the shoemay be applied to the heel without breaking it is` limited and also that the. pressure under which. quick setting thermoplastic resin must be injected into the cavities and voids in order to be 4effective is substantial. V It has been found that when a heel is attached to Va shoe in accordance with the above practicer there is a tendency for the thermoplastic resin to seep out from between theheel seat of the shoel and the rim or the breast edge of the attaching face of the heel with the result thatthe finish of the shoe is impaired. Suchseepage is usually caused by the high pressure of the. softened thermoplastic resin which is injected between the heel seat of the shoe and the attaching face of the heel opposing and thus rendering less effective the heavy molding pressure of the heel against the heel seat of the shoe. It will thus be apparent that when-the pressure of the viscous or softened thermoplastic resin between the heel present. invention an improved method of per- 2 Claims. (Cl. 12-147) and the heel seat of the shoe reaches a certain point it reduces the heel attachingv pressure sufliciently to cause the heel tomove slightly away from its molding position upon lthe heel seat of the shoe in which position it is desirable that the heel remaingduring and after its attachment tovtheshoe. l t f 'f Such movement of the heel from its molding position uponthe heel seat of the shoe may or may not be accompanied by the above-mentioned seepage but impairs the general appearanceof the shoe since the heel does not then merge attractively with the counter portion of the shoe. It is an object of the present invention to `provide an improved method of attaching heels to shoes by the vuse of thermoplastic resin. With the above object and considerations in view there is provided in accordance with a feature of the manently securing together two parts o-f an article, for example, a shoe and a heel, said method comprisingV providing the attaching face of the heel and the heel seat of the shoe with opposing anchoring cavities, forcing the heel with heavy pressure against the heel seatoffthe shoe,` injecting under initiallyvhigh pressures a mass of viscous thermoplastic material into `said cavities and also intovoids formed between the heel and the heelseat of the shoe, reducing to a minimum the pressureunder which the therm'oplasticY material is injected into the cavities and voids as said cavities and voids are filled, andmaintaining the heel forced with heavy pressure against theheel seat of the shoe until the adhesive has set.
The heel and'thershoe constructions hereinafter illustratedare generally similar to .those disclosed in said Patent No. 2,447,512. After the heel has been clamped against the heel seat of the shoe softened thermoplastic material which is of the resinous type and will hereinafter be referred to asresin is forced through a passage in the heel corresponding to the above-mentioned passage by an injector or gun having a nozale which ts in the tread'end of said passage, the resin filling the undercut cavities in theheel` and the heel seat of the shoe and also filling the voids between said heel seat andthe attac-hing vface of the heel. In order quickly and effectively to ll said cavities and voids with thermoplastic resin and also to avoid the above-mentioned drawbacks the illustrative injector is adapted Y initially to force the softened thermoplastic-resin 3 into the cavities and voids under high nozzle pressure of approximately 1600 pounds per square inch which is thereafter reduced below 390 pounds per square inch, for example, so that when the cavities and voids are approximately filled and the resin pressure between the heel seat of the shoe and the heel begins to build up, the injecting nozzle pressure will be below 390 thereby insuring against moving'the heel away from its proper molding position upon the heel seat of the shoe and also insuring against the above-mentioned seepage of the resin.
Injectors or guns and a machine for clamp-` ing heels to shoes in the practicing of the above method are described in detail and claimed in the above-mentioned Patent No. 2,600,507. Theabove y and various other features of the invention will be understood and appreciated from the following detail description read in conjunction with the accompanying drawings in which Fig. 1 is an exlploded view showing in `perspec-l tive a composite insole, partly broken away and heel seat and sock lining tucks prior to their assembly in the manufacture of a shoe to which a heel is to be attached by thermoplastic resin in accordance with our improved heel attaching method ;v
Fig. 2 shows in perspective a heel and the rear end of a shoe, partly `broken away, which is ready to receive a heel;
Fig. 4 is a section on line IV-IV of Fig. 3`
after the thermolplastic'resin has been injected into the undercut cavities in the heel seat of the shoe and the heel and has been allowed to set to attach the heel permanently tothe shoe;
Fig. 5 is a side elevation, partly broken away" and partly in section, showing a heel clamping machine and an injector' in the process of forcing resin into the undercut cavities of the heel seat of the shoe and the |attaching face of the heel clamped against the shoe;
6 is a section online VI-VI of Fig/5y Fig` '7 is a vertical section corresponding in part to Fig'. 5 showing portions of a slightly modified injector or gun;
Figs. 8 and 9 are angular viewsshowing in; del tail portions of ya heel engaging member of said heel clamping machine.
As explained in the'above-mentioned Patent No. 2,447,512, in the manufacture of womens shoes I8 (Figs. 3, 4 and 5) it has been proposed? to a attach awood heel 20 of the Cuban type to the heel seat 22 (Fig. 2) of the shoe by thermoplastic resin, for example, while the heel is clamped under molding pressure to the heel seat of the shoe, said resin being-injected into a pasr sage or bore 28 (Figs. 2, 3, 4 and 5) extending heightwise through the heel and filling undercut reentrant or anchoring cavities 28 (Figs. Zand S), 30 (Figs. 2, 3 and 4) in the attaching face 32 of theheel and the heel seat 22 respectively as well as all voids or spaces 34 (Figs. 3 and 4) formed between the attaching face of the heel and the heel seat. The cavity 28 in the attaching face 32 of the heel 20 comprises a pair of intersecting undercut slots 36 having the appearance of the- Y letter X as viewed when looking down onsaid attaching face of the heel. The illustratedslots 38 extend into close proximity to the rim 38 (Fig.
'the vheel end or counter portion 50 'of which consist-sof a layer of outer leather 52, a fibre counter 5ft and a lining 56, all suitably sewed together, heel seat lasted and secured to the heel seat of lthe reinforced insole by tacks 58; a metal shank stiffener 60 which is secured at its forward end to the reinforced insole All by staples (not shown) and an outsole S2 (Figs. 2 and 3) which is adhesively securedto a roughened overlasted margin B4 (Fig. 2) of the shoe upper 48 and the heel seat of which has been reduced to provide a heel seat tab 66 and heel breast receiving shoulders 68 engaged in the finished shoe by the forward end of the attaching face 32 and the breast 'i0 (Fig. 3)
respectively of the heel.
The composite insole 40 consists of a forepart l2 (Fig. l) and a paper-board shank and heel seat portion 'Ill intertted and cemented together. The undercut cavity in the heel seat 22 of the shoel is formed by providing inthe heel-seat ofthe composite insole 40 'an opening 'IG (Figs. 1 and 2) having ringer portions 'I8 extending close to the heel seat margin of the sole, and forming in the heel seat tuck 44 prior to its attachment to the insole, an opening slightly smaller .than the central part of the openingv 1S, the construction and arrangement being such that when the sock lining 46 yand the heel seat tuck 44. are cemented to the composite insole d0 there are formed a plurality of undercut nger. portions of the cavity 30. It will be noted that the rear end of the shank stiifener 60 extends intothe void or space between the undercut cavities 28, 30 in the attaching face 32 of the heel and the heel seat 22 ofthe shoe I8 and that when viscous thermoplastic resin is forced under pressure through the passage 28 into the heel by the use of a gun of the type described in said Patent No. 2,447,512, the resin llsthe undercut cavities 28, 38 and all voids 34 between the heel seat 22 of the shoe and the attaching face 32 of the heel and Vif desirable approximately all of the passage 26 as best shown inFig. 4.
Preparatory to the permanent attachment of the heel 28 to the shoe I8 the rim 38 of the attaching face 32 rof the heel. is forced with heavy molding pressure against the outer edgeof :the overlasted margin V82 (Figs. 2, 3 and 4) of the .counter portion 50 of the shoe and the breast .10 (Fig. `3) .of the heel 20 is forced against the heel breast receiving shouldersv (Fig. 2), the forward end lof the attaching face of the heel restingupon the heel seat tab 66. It is desirable that the overlasted heel seatv margin 82 ofthe Lshoe shall be planar so that the entire rim 38 lof has high'and low spots and accordingly itis necessary to force the rimr38 of the heel-20 with heavy molding pressure' against the heel seat of the shoe before and while the heel is being yattached-'to the shoe in order tofinsure that'the rim of the heel shall fhug and merge attractively with the counter portion of the shoe. As pre- .acoagoei viously explained the amount. of pressure that-can be applied against the Wood heel without damaging itin forcing it against the heel seat of the shoe is limited,- o-poundsbeing about the maximum pressure commonly used inthe attachment of theaverage Cuban heel tothe shoe.v
In the attachment of heels to shoes by the use .of thermoplasticv .resin which sets fairly rapidly it has been the practice vto inject the softened resin into the'cavities28, 30 inthe attaching'face A32V of the heel and the heelseat. 22 of. the shoe and into the voids 34'betweenv the attaching face of the heeland said'heel seat under. a substantially uniformly high and sustained nozzle pressure, for example, of about 1600 lbs.per square inch in order to insure that the resin shall be effectively injected intoand ll such cavities and voids before having a chance substantially to set. As above explained when heels are being attached to shoes by viscous thermoplastic resin injected ditions-as above explained are due to the fact that when softened resin. is injected into the cavities 28, 30 and the voids 34after said cavities and voids are substantially full, a high pressure isv built up beneath the attaching face of the heel, such pressure opposing and thus reducing the pressure which is forcing the heel against the heel seat of the shoe.
With the foregoing considerations in view we propose to force, as above explained, under high pressures a substantial quantity or mass of softened thermoplastic resin into the cavities 28, 30 andthe voids 34, a remaining quantity or'mass of softened resin necessary to ll the undercut cavities and voids being injected into said cavities and voids at low pressures, so that pressures imparted lto the mass of resin substantially. lling the cavities land voids shall not be greatenough to oppose the heel clamping pressure sufnciently Atorcause the Aabove-rnentioned undesirable conditions;
There are disclosedin said Patent No. 2,600,507 twoinjectors or -guns foruse in practicing our method, Figs. 5, 6, 7 and 8 of vsaidrapplication illustratingV an injector or gun 84 which injects softened thermoplastic resin at initially high but gradually diminishing pressures into the cavities 2.8', 30 and thevoids 34.and Fig. 9 of said application which corresponds to Fig. 7 of the present application illustrating an injector or gun 86 which is substantiallylike the above-mentioned injector but which injects a predetermined amount of softened thermoplastic resin into said cavities and voids under high diminishing pressures and then injects into the cavities and voids unde'rjlow diminishing pressures an amount of softened thermoplastic resin necessary to ll said cavil'rlesv and voids.
. The injectors. or guns 84. 86 when full hold a quantity or mass of resin slightly greater than that required to ll the cavities 28, 30 and the void-s 34 in the attachment of a heel to the largest -shoe ,operatedupom said guns having secured to them a locking plate or coupling |08 for quickly andeftectively coupling the gunsv to an extruder (not-shown): preparatory to receiving a .new chargek of viscous thermoplastic resin..A i
The injector 84rhas a steelbarrel l0 .(Fig. V5') the peripheryV of whichis recessed for receiving an electric. heater. ||2, `therebeing secured .to the ybarrel a casing ||4 for covering said heater. The barrel l0 is bored to provide a cylindrical resin receiving recess or chamber I6., Threaded onto the barrel l|0 and insulated from yportions of it by anV insulating washer4 isany aluminum spring'housing |23 havingat its Ylower endif-a cylindrical recess |22 and 'having threaded vinto its upper end a cap |24. Sli'dingly mountedi'n the chamber ||6 is a hollow plunger |26which has an enlarged flanged portion |28y tted for sliding movement in the recess |22 ofthe housing |20, a heavy spring |30 which is interposed between the flanged portion |28oi the plunger and the cap |24 of the housing |20 serving constantly to urge the 'plunger' into the chamber. i
Screwedv onto the barrelis a valve block |32 having a two-part tapering recess orv passage f 34, an upper portion of which is in alinement with the lower end of the chamber I6 and into-which opens an inlet passageor conduit |36 for receiving lviscous thermoplastic resin.l To thelower end of the valve block |32 isfsecured a nozzle. .|38 which has a shoulder |39 and is constructedand arranged to t in thev passage orbore 26 in the heel 20 and which has a? passage |40 in communication with'the 'lower' portion of the tapered re'- cess |34. Formed in the valvev block |32 is a bore |42 serving as a bearing "for a rotary va1ve|44 having a tapering recess |46 which may be moved into alinement with the upper and lower portions of the tapering recess |34 to'permit resinlinthe chamber |6 to-be forced vby the spring actuated plunger |26 out through'the passage |401 offthe nozzle |38 orwhich may be moved into fairetracted position to cut oiI communication; be-
tweenthe upper and lower portions of. therecess |34 and accordingly. ejection. of thermoplastic resin from the nozzle. j L
Either one of the injectors or guns84, 66' may be quickly and eiectively coupled to the extruder as explained in detail in said patent No. 2,600,507. After the thermoplastic resin from the extruder has passed under extrusion Apressure through' the passage |36, |34 into the chamber ||6 itraises the plunger |26 against the action of the spring |36, the chamber continuing to lll until the upper end of the plunger engages a normally closed microswitch |62 which is carried bythe cap |24 of the spring housing |20 vand is secured'to `the cap by a terminal housing |63 thereby breaking a holding circuit andV accordingly deenergizing a solenoid operated switch tocause'theyopening of a circuit for -the extruder motor. i
`Various thermoplastic materials: 'are suitable for use in the practicing of ourmethod. An example of one composition which 'may be used successfully is as follows:
` Parts lby weight Ethyl cellulose (50 or 100 centipoise viscosity) ethoxy content, 45.0446.5% -250. Diphenyl (O-xenyl) phosphate v .50 Phenolic resin `30 Methyl phenol 4.5 Calcium stearate ".3'.0
Thermoplastic resins such as disclosed above.
and in said Patent 2,447,512 shrink as they cool. Thls property is utilized `toadvantage since the l'resin upon cooling pulls the. rim of the attaching face` of the heel against the heel seat of the 7 shoe with sunicient pressure to insurethat the heel merges` .gracefully with the .shoe upper.. 1 It maybe desirable slightly toincrease theshrinking property of the resin; an example of vsu'cha resin which-may be successfully used being as follows:
j i l Parts' by weight AEthyl Cellulose (50 or 100 centipoise viscos-v a pinion |12secured to the valveand which is slidably mounted in guideways |14 (Fig, 6) formed in spaced projecting ears |16 of the valve block |32. The rack carries a pivot pin |18 upon which is Vvmounted a block |80 into which is threaded the lower end of a rod |82, the upper endof said rod being pivotally connected to a lever |84 journaled on a pivot pin |486' carried by a bracket |88 clamped bya screw |81 to the spring housing |20.VV The rack |10 `may be initially adjusted with relation to the rod |82 to insure that the tapering recess |46 may be moved into its proper stop position in alinement with the tapering recess |34, after loosening a lock nut |90 which is threaded onto the lrodand may be clamped against the blockvf|80j to` maintain the rod in -its adjusted position with relationto the block.
Surrounding the rod |82 andfinterposed between the nut |90 and the bracket |88 Yis a spring |92 for constantly urging the rack r|10 downward until shoulders |94 (Fig. 6) ,of the valve |44 engage the ears |16 of the valve block` |32. Se'- cured by screws (not'shownltoy the ears |16 of the valve block |32 'and to ythe vbracket |88 is a wood handle |98 which is used by the operator in'handling and operating the ejector or gun, said lever |84A having secured to it by screws 200 a woodhand piece 202 which when depressed raises the rack |10v into a position in Vwhich-the tapering recess |46 is in alinement withlthe upper and lower portion ofthe tapered recess |34, such position being determined by the engagement of the shoulders |94 of the valve |44 with the ears |16 of the valve block |32; f
It is importantthat the temperature of the thermoplastic resin 24 in the various parts of the injectors or guns 84,' 86 be retainedV sufficiently .high to insure the proper ilow of said resininto the undercut cavities 28, 30 in the attaching face 32 of the heel 20 and heel seat 22 of the shoe i8 and into the voids 34 between the attaching face of the heel and the heel seat of the shoe. Accordingly,V the extruder head 96 has inserted in it fourV electric heaters (notshown) and the valve block has two electric heatersV (not shown).
In order readily to determine the temperatures of the valve block |32 there are provided thermometers (not shown) having stems tting in recesses of said block.
As above explained the injector of gun 84 may be replaced by the injector or gun 86 villustrated in Eig. 7 Vin orderguickly and eifectively to inject under heavy pressure into the undercut cavities 28, 30 in the attaching face 32 of the heel and the heel seat 22 of vthe shoe and intoyods 34 formedrbetwejenthe attaching face of the heel and the heel seat of the shoe a A,quantityor mass of softened thermoplastic resin whichwill .'ll a large percentage of ,said cavities,- and voids. and thereafter to inject into -said cavities and voids under light pressure a quantity of softened thermoplastic resinsuicient-to ll said.,cavities .and voids.jThe injector, or-gun 86 which mayfbe referred lto as a modified=injector,jexceptj for hereinafter described parts, vis similarzgto ,the injector or gun 84 and comprises a spring-housing 240 which corresponds toV the spring housing |20 and has a cylindrical recess r242. Interposed between a cap 244 threaded intoand forming part of ,the`housingo240v and a flan'ger246at the lower end of a drum 248 slidable inthe recess 242 is a heavy or strong spring 250. 1 Slidably movable in a cylindrical resin receiving recess .or chamber 252 substantially like the 'recess' or chamber |6 of the injector or gun 84 is ga. plunger 254, the upper end of which is slidable 1in a guideway 256 of the drum 248said plunger 'having formed in it a borey 258 for receivinga relatively light or weak spring 260,*the upper end oiwhich engages a spring retaining projection 262 of the cap 244. The plunger 254 `is oonstantlyu-rged to its loweredposition in the resin chamber 252 by they springs 250 and 260 the lower limit` of .travel of the plunger 254 in the chamber 252 being determined bythe engagement of a flange 26.4 of the plungerwith a stop or face 265 ofthe housing 240.- Upward movement of the plunger 254 with relation to the drumv 248 is -limitedfby engagement of the flange 264 of the plunger with a stop or face 266 of the drum. 1
It will thus-be clear that when viscous thermo;- plastic resin is forced under' pressure into the cylindrical 'chamber 252`the plunger 54v is raised against the action of the relatively light spring 280 until the flange 264 -of the plunger engages the face 266 of thezdrum 248, the plunger Aand the vdrum thereafter being moved upward together against the action of' the heavy spring 250 and the light-spring 260 under pressure appli'edto-.lthe plunger by the softened thermoplastic resin entering s-aid chamber. As in the injector, orfgun 8'4, rotation of the extruder screw 82 and accordingly upward movementof the'drum2-48fi1nder theaction of the viscous resin forced intothe' vgun by the extruder '88 is limited by .thefengagement of the upperlend of thedrum with a microswitch 268 corresponding to the microswitch |`|2-.` .-As above explained in connection with the injector or gun 84 once theI eXtruder-Srhas beenlslopped, the switch |68 has to be manually operated in order again to start the extruder.
The heel 20 maybe quickly-andeifectively forced against the heel seat 22 vof .the shoe |8 by the use of the machineor clamp which is illustrated in Figs. 5, 8 and 9.an'd which as will appear lateris constructed and arranged to en;-
able the nozzle |38V of the injector 'or 'gun 8401v 86 to be inserted into the passageorbore126 of the heel clamped against the heelseat ofj the shoe. The illustrative heelAclamping'mach-ine comprises a frame 210 ('Fig. 5) 'whichis bolted'to a bench (not shown) or other suitable support and has secured to it by screws 212and-a fulcrum screw 21'4 a yoke 216. Slidingly adjustableon a guide portion 218 (Figsz and Slat-the upper end of the yoke. 216 is a split supporting bracket 280 having arpa-ir of forwardly extending bifurcations 28'2, the bracket -being secured in different adjusted positions on said guide 'portions by'fa binding screw' 284.'v Pivotally 'suppor-ted'in alined bores l286 of the Ybifurcations 282 are-pins 288 which are secured by screws 29| to a tread end abutment or plate 290I (Fig. 9) and which are pinned t'o a pair of rearwardly extending arms 292;"'int'o the rear5 ends of which are threaded screws 294 extending through slots 296 Yina U- shaped 'gage supporting member 298 arranged in guideways 299 formed in said arms. The abutment 290 has a flat lower heel engaging surf-ace 300 and a tapered opening 382 through which the nozzle |38 of the injector is inserted preparatory to injecting resin into the passage 26' of the heel 20 to be attached tothe shoe I8.-
Adjustable into -diiierent forward and rearward positions in a guideway 334 of the gage supporting memberv 298 after releasing the locking screw 30Bis a V-shaped back gage 308 constructed and arranged to be engaged by the rear face of the heel, the abutment 299 and the back gage 308 being movable as a unit into a predetermined angular 'operating position about an axis 3I0 of the pins 288 against a screw 3|-2 which is threaded into the split bracket 280 and is engaged by an abutment 3I4 forming part of the gage supporting member 298. It will be clear that the abutment 290 and the back gage 308 may be moved as a unit into different angular positions about the axis 310, the friction between the pins 288 and the forwardly extending bifurcations 282 of the bracket being s-uicient to retain the abutment block 3I4 in its operating position against the stop screw SI2.`
The back gage 308 may be moved into different adjusted positions along the guideway 304 of the supporting member 298 and may be moved into different adjusted positions generally heightwise of the heel by raising or lowering the gage supporting member 298 along the gui'deways 299 of the arms 292. The various members which are supported by the bifurcations 282 and comprise the abutment 290` and the back gage 308 may be described as a holder.
The shoe I8 mounted upon a last or form 3I' is supported in the illustrative heel clamping machine by a knurled support 3I8 fulcrumed on a pin 320 secured to a lever 322 which is Apivoted upon the fulcrum screw 214, said lever having a cylindrical recess 324 for receiving an upper ball end 326 of a manually operated thrust member or screw 328 threaded into the yoke 21'6. The lever 322 is constantly urged against the ball end 326 of the screw 328 by a spring 330, opposite ends of which are attached to hooks fixed to the lever 322 and to the yoke 216. The fulcrum screw 214 is so positioned with relation to the yoke 218 that when the lever 3212 moves clockwise as viewed in Fig. upon upward advancement of the screw 3128 in the yoke, said lever moves the support 3I 8, then in engagement with the cone of the last 3 I I6 upon which the shoe is mounted, heightwise and rearward of the shoe. The heightwise and rearward components of movement of the knurled s-upport 3 I 8 carried by the lever 322 may be varied by moving the yoke 21S into different adjusted positions upon the frame 218 so as to change the location of the fulcrum screw 214 about which the lever 322 pivots with relation to the yoke 216.
In practicing our improved heel attaching method the operator places the heel 20 upon the fitted heel seat 22 of the shoe I8 and after moving the tread face of the heel assembled with the shoe into engagement with the lower face 300 of v shoe'the pivotally mounted holder which comprises the abutment 290 and the heel gage 308 is moved to its frictionally held operativepositionagainst the screw 3|2. Clockwise rotation offthe'h'a'nd screw 328 as viewed from below causes the lever 322 to swing lclockwise as viewed in Figl with the result that the vknurled 4support `3I8 is'moved upward and rearward causing the heel sea-t 22 of the shoe to be forced with considerable pressure against the attaching'fac'e of the heel'held against movement by the'abutment 298fandthe back 'gage 388 and the heel breast'recei'ving shoulders 680i the sole 62 of the shoe to be'forced against the breast of the heel with considerable pressure. The upward and rearward components of movement of the support 3I8 may be varied to increase or decrease the amount of pressure of the heel breast receiving shoulders 68 against the breast 18 or the heel by changing the position of the yoke 216 with relation to the axis of the fulcrum screw 214.
In order permanently to attach the heel 20 to the shoe I8 by thermoplastic resin 24 after clamping the heel against the heel seat 22 of `the shoe in the heel clamping machine above described, the operator grips the handle |98 (Fig. 5) of the injector 84v which is then attached to the extruder and the chamber H6 of which has been filled withv thermoplastic resin, and rotates the injector to uncouple the injector from the extruder. The injector 84 is then bodily transferred to the heel clamp and the nozzle |38 of the injector is inserted through the opening 302 in the abutment 29) and into the passage or bore 26 of the heel, the ange |39 of the nozzle resting on the upper face of said abutment.
The handle 262 of the injector 84 is then depressed causing the thermoplastic resin in the chamber llt to be forced with gradually decreasing pressure into the undercut cavities 28, 30 in the attaching face 32 of the heel 29 and the heel seat 22 of the shoe as well as into the voids 34. When the cavities 28, 38 and the voids 34 have been filled with resin the passage 26 in the heel starts to ll and the injector is moved out of the passage under pressure of the resin which progressively lls said passage. As the end of the nozzle |38 approaches the top lift receiving face of the heel the operator, in response to the indication received from this movement of the injector, manually releases the handle 292 of the injector and moves the injector away from the work, the injector again being placed in its thermoplastic receiving position on the extruder head 96 to receive, after a switch (not shown) has been manually closed another supply of thermoplastic resin prepara*- tory to operating upon the next shoe. The screw 328 is then released and the shoe which has been operated upon is removed from said machine.
The practicing of the method by the use of the injector illustrated in Fig. 7 is substantially theV same as that above described, the only difference .beingl that the thermoplastic resin is ejected from the chamber 352 rst under the action of the springs 250, 250 and thereafter under the action of spring 260.
Having described our invention, what We claim as nav/*and desire to secure by Letters Patent cavities and into any voids existing between said Work pieces a mass of viscous thermoplastic resin which almost iills said cavities and voids, and forcing under radically reduced pressure into said cavities and voids `before the cavities and voids become lled, an additional mass of viscous thermoplastic resin suicient to iill said cavities and voids.
2. The method of permanently attaching a heel to a shoe which comprises providing a shoe which has in its heel seat an anchoring cavity, providing a heel having in its attaching face an anchoring cavity, clamping the heel under heavy pressure against the heel seat of the shoe, forcingjunder heavy pressures into said cavities and into any voids existing between the heel and thevheel seat of the shoe a mass of viscous thermoplastic resin which almost fills said cavities and voids, and forcing under radically reduced pressure into said cavities and voids, before the cavities and voids become lled, a further mass of viscous thermoplastic resin suf cientrto iill said cavities and voids. y A
JAMES F. LEAI-IY.
JOHN W. ASHLEY.
REFERENCES YCITED The `following references are of record Vin the le of this patent:
UNITED STATES PATENTS Number Name Date 2,433,132 Lester Dec. 23, 1947 2,447,512 Leahy Aug. 24, 1948 2,461,282 Jobst T Feb. 8, 1949