US2795822A

US2795822A - Method for making shoes

Info

Publication number: US2795822A
Application number: US287112A
Authority: US
Inventors: Miles H Long
Original assignee: United States Rubber Co
Current assignee: Uniroyal Inc
Priority date: 1952-05-10
Filing date: 1952-05-10
Publication date: 1957-06-18
Anticipated expiration: 1974-06-18

Description

June 18, 1957 M H LONG 2,795,822

METHOD FOR MAKING SHOES Filed may 1o, 1952 s shuts-sheer 1 M. H. LONG METHOD FR MAKING SHOES Jun 18, 1957 5 Sheets-Sheet 2 Filed May 10, 1952 NQNN June 18, 1957 M. H. LONG METHOD FOR MAKING SHOES 3 Sheets-Sheet 3 Filed May l0, 1952 ff .ATT

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United States Patent C i METHOD FOR MAKING SHOES Miles H. Long, Montoursville, Pa., 'assignor to United States Rubber Company, New York, N. Y., a corporation of New Jersey Application May 10, 1952, Serial No. 287,112

6 Claims. (Cl. 18-59) This invention relates to the method of making shoes and particularly to the method of casting an outsole onto a shoe upper and producing toe spring in the sole.

This invention is useful in the manufacture of shoes having soles cast thereon, and it is particularly useful for imparting toe spring to shoes manufactured by the method and apparatus disclosed in United States Patent No.`

2,786,237, which issued on application Serial No. 361,392, led June 12, 1953, a continuation of application Serial No. 192,086, led October 25, 1950, which last mentioned application has been abandoned, of which I am a coinventor, and wherein my improved last is substituted for the last shown in said patent. The term toe spring as used herein is the upward curvature of the periphery of the bottom of the toe portion of the shoe sole, or the upper edge of the foxing, which curvature takes the form of the normal upward curvature of the foot beyond the ball portion of the foot. The sole and foxing may be cast from any suitable liquid material, for example liquid gelable rubber latex, and at the time the shoe sole is cast from the liquid materiaLin anopen mold onto the bottom of the lasted shoe upper as described in the prior application, the periphery of the bottom of the toeportion of the solelies in a plane parallel to the plane of the level of the liquid material in the mold cavity from which 'the sole is cast, and therefore the shoe is not provided with toe spring when the sole is cast thereon and so long as the toe portion of the sole remains in the cast position. Such parallel arrangement of the plane of the periphery of the bottom of the toe part of the last is required to produce a uniform thickness of sole or uniform height of foxing at the periphery of the bottom of the toe part of the sole by the casting operation. 1

In accordance with my invention, my improved `last is used in the casting operation under the above conditions. The last comprises a toe part and a heel part, which are hinged together near the ball portion of the foot. The shoe upper is lasted on the last, and the periphery of the bottom of the toe part, which lies in a plane is pivoted to its lowermost position, and arranged parallel to the liquid level ofthe casting material in the mold cavity when the sole is cast upon the lasted upper. The toe spring is subsequently imparted to the cast sole by pivoting the toe part of the last, and the corresponding part of the shoe, in respect to the heel part, from the sole casting position to an upwardly inclined position, or toe sprung position. The pivoting movement is made before the cast l sole has received its nal set and then the sole is given its final set or cure, whereby permanent toe spring is imparted to the shoe.

The invention is further described in reference to the accompanying drawings, in which:

Fig. 1 is a side elevational view of an apparatus with which my improved process may be carried out, and showing the upper portion of my improved last;

Fig. 2 is an elevational View of my improved last;

Fig. 3 is a horizontal cross sectional view of the top portion of the last'taken ou line 3 3 of Fig. 2;

2,795,822 Patented June 18, 1957 Fig. 4 is a bottom plan view of a modified formof my improved last;

Fig. 5 is a cross sectional view of a shoe in a sole mold taken on a line indicated by the line 5-5 in Fig. 4, and showing a modied form of the last in full side elevational view with the shoe thereon; and

Fig. 6 is a longitudinal cross section of a toe portion of a further modication of a shoe embodying this invention.

My invention relates to the improved lasts shown in Figs. 2 to 5, and the use of the lasts in the process which Will be described in reference to the apparatus shown in Fig. 1. l

Referring to Figs. 2 and 3, the last 10`comprises a toe part 11 and a heel part 12, which are hinged together with a hinge joint 13 located above the ball portion of .the last. The last 10 may be made of any suitable-material, preferably metal, which is cast in the form of a-hollow shell 14 in accordance with the usual practice, as shown in Figs. 1 and 3.

Any suitable form of hinged joint may be used for pivotally connecting the toe part 11 to the heel part 12, but as shown herein the joint 13 comprises a cylindrical projection 15 on the toe part 11, which lits into ;a cylindrical socket 16 in the heel part 12. The joint 13 is held together by a bow spring 17, which is located within the shell 14 and is held under tension between a pin 18,;in toe part 11 and a pin 19 in the heel part 12. One;en d of the spring 17 is hooked around the pin 18 which passes through the toe part 11 from one side of the shell to the other, and the other end of the spring 17 is hookedaround the pin 19 which passes through the heel -part12 fronrone side of the shell to the other. `The toe part .11 is shown in full line position in Fig. 2, which is the sole casting position of the toe part. In that position, the center of the pin 18 in the toe part is located on a line 20 passing through the centers of the pins 18 and 19 and below Ythe center 21 of the hinge joint 13. The toe part11 is adapted to be pivoted from its full line position, or sole casting position to a toe sprung position as shown by thefdotand-dash lines. When in the toe sprung position, the line 20 passing through theA centers of the pins 18 and 19 moves to a position 22 above the center 21 of the hinge joint. In the operation of this construction, when theV line 20 passes over the center 21 ofthe hinge joint in .either direction, the toe part is snapped by the spring k17 from the sole casting position to the toe sprungv position, or vice versa. Such action is referred to hereinafter as snap action, which is produced by the snap acting spring 17.

The toe part 11 of the last 10 is moved from its sole casting position to its toe sprung position, or at least over the dead center of the hinge joint (which is that position of the toe part 11 when the line 20 between the pins 18 and 19 intersects the center 21 of the hinge joint 13), by the longitudinal actuation of a rod 23, which is pivoted at one end to a pin 24 passing through the toe part 11 from one side of the shell to the other, and at the other end to .a crank pin 25, as shown in detail in Fig. 3. The crank pin 25 comprises a screw which is threaded into the end of a shaft 26 at a point which is eccentric to the axis of rotation of the shaft 26, which is rotatably mounted in a bearing formed in a bushing 27 threaded into a cylindrical web 28 cast into the shell 14 of the heel part 12 of the last 10. The shaft 26 is provided with a hexagonal socket 29 for the reception of a wrench, or key, which is adapted to be used to manually turn the center of the crank 25 from the forward position shown in Figs. 2 and 3 to the rearward position, so as to pivot the toe part 11 from the full line position to the dot-and-dash line position. When the crank pin 25 is turned through 90 from its forward or rear position, the line 20 between the pins 18 and 19 passes over the dead center point of the hinge 3 joint, and the spring 17 snaps the toe part to its nal upward or downward position, which may throw the crank the remaining 90 over to a 180 position, where the crank pin 25 is on dead center, that is in line with the center of the shaft 26 and the pin 24, and tends to maintain the toe part 11 positively in either the sole casting or toe sprung positions.

In order to compensate for the shrinkage in a sole which may be cast on the bottom of a shoe upper, the bottom 30 of the last 10 is made in a convex shape, as indicated by the curved line 31 extending from heel to toe. The bottom 30 is also curved in the transverse direction, as indicated by the space between the

lines

31 and 32, which latter line represents the plane of the periphery of the bottom of the last. In the performance of the operation of casting a sole on a shoe of the type shown in Fig. l, in order to provide a uniformly thick 'sole or `a uniformly high foxing at the periphery of the sole, the -periphery of the bottom of the last should lie in a single plane, as indicated by the line 32, and when the sole is cast upon the lasted upper, such plane is arranged parallel to the liquid level of the casting material in the sole molding cavity. In other types of shoes the thickness of the cast tread surface may vary in the instep and heel portions, and the bottom of the instep and heel portions of the last may be shaped to accommodate an arch support and a raised heel, as described in reference to Fig. 5. However, in all types of shoes made in accordance with this invention, the periphery of the bottom of the toe part of the last must lie in a single plane, and such periphery must be arranged parallel to the liquid level of the sole casting material in the mold for the purpose of producing the desired uniformly thick sole and uniformly high foxing at the toe part of the shoe. In the event a foxing is cast integrally with the cast sole, the last is preferably provided with a vertical peripheral side portion 32a extending upwardly from the periphery 32 of the bottom of the last a distance equal to the height of the foxing to be produced. As shown in Fig. 2, the top periphery 33 of the side portion 32a terminates in a plane parallel to the plane of the periphery 32 of the bottom of the last, as represented by the line 33.

The method of casting a flexible sole from a liquid casting material onto the bottom of a lasted shoe upper, and producing toe spring in the cast sole, is illustrated in Fig. l, in which an apparatus is shown for carrying out the process with the use of the last shown in Figs. 2 to 5. Referring to Fig. 2, the last 10 is provided with the usual lasting stand pin recesses 34 for securing the last to a lasting stand (not shown). The last 10 is placed on the lasting stand, and a shoe upper 34a is lasted thereon over an insole in the usual manner or otherwise applied thereto in the conventional slip lasting process. The last 10 with the lasted upper thereon is then placed in a sole casting pig 35, while it is elevated to the dot-and-dash line position, as shown in Fig. l. The liquid casting material is placed into a sole forming cavity 36 formed in an elastic exible mold 37, which is secured to a base 3S in a fixed position. The lasted shoe upper 34a is then lowered into the mold cavity until the casting material rises therein to the level of the top edge of the outer periphery of the shoe sole, or to the top edge of the foxing to be cast thereon. Preferably the mold cavity is so designed that the top rim of the mold cavity is level with the liquid level of the casting material after the shoe is placed in the mold cavity to the desired depth, with the lower side walls of the upper equally spaced from the side walls of the cavity and with the bottom of the lasted upper substantially parallel to the bottom of the mold.

At the time the bottom of the lasted upper is lowered into the mold cavity, the toe part 11 of the last is pivoted to the full line position as shown in Fig. 2, and the periphery ofthe bottom of the last as represented by the plane 32 is arranged parallel to the liquid level 39 ofthe casting material. The shoe remains in the mold cavity until the casting material solidiiies thereon and forms the outsole 40 and foxing 41 thereon. The casting material is preferably gelable rubber latex as described in the aforesaid Patent No. 2,786,237. After the sole has congealed onto the upper and becomes suficiently tough, the last 10 with the upper and sole cast thereon is Vremoved from the mold cavity by elevating the casting jig 35 to the dot-and-dash line position shown in Fig. l. The last 10 may then be removed from the jig, and the toe of the shoe is pivoted upwardly to its toe sprung position either before or after removal by inserting a key into the socket 29 of the shaft 26. The key is turned through and the shoe sole 40 is pivoted to its upward or toe sprung position, in which it is given a nal set to impart permanent toe spring thereto. The set or cure may be produced by the usual vulcanizing process, or heat treatment while the shoe remains on the last ina hot air oven at atmospheric pressure, and without confining the sole in a mold.

As described more fully in the foresaid prior application, a sole cast from gelable rubber latex is caused to shrink as a result of the extraction of the liquids during the casting, drying, and curing of the sole. In order to resist shrinkage of the outsole and cause the shoe to retain its toe spring after the sole has been cured, a stit layer of material is incorporated in the bottom of the shoe. As illustrated in Fig. 1, the stiff layer may be incorporated in the shoe in the form of an insole 40. The upper 34a may be lasted over the insole 40', and at the time of the lasting operation, the insole is moldable and it is caused to conform to the shape of the bottom of the last during the lasting operation, and to the upwardly curved shape of the toe part of the sole when it is subsequently sprung from the sole casting position to the toe sprung position. The insole is heat curable and is converted from its moldable state to its permanently fixed stift state during the cure of the outsole a-nd thereby assists in causing the shoe to retain its iinal toe sprung position. It has been found that an insole made of uncured vulcanizable rubber rag stock, which is adapted to vulcanize during the vulcanization of the cast outsole, is suitable for this purpose.

The jig 35 is provided with a hand wheel 42 which is rotatably mounted in the jig arm 43. The hand wheel 42 is provided with a stern 44, which is rotatably secured in the arm by a pin 45 extending through the arm 43 into a groove 46 in the stern 44. The lower end of the stern 44 is provided with screw threads, which are threaded into the threaded bore 47 of the last 10 to secure it to the jig arm 43. Locating pins 48 anchored in the arm 43 extend into the lasting stand pin recesses 34 of the last 10 to orient it on the jig 35.

The jig arm 43 of the jig 35 is aixed to a shaft 49 pivotally mounted between two bearing brackets 50, one of which is provided with an arcuated plate S1, having recesses 52 and 53 for receiving the .end of a manually operable spring pressed rod 54 slidably mounted on the arm 43 of the jig. When the end of the rod 54 is received by the recess 52, the lasted shoe is retained in the sole casting position in the mold cavity 36, and when the rod 54 is in the recess 53, the lasted shoe is held in the elevated position as shown by the dot-and-dash lines, where the last 10 is secured to and removed from the jig.

A modified form of the last 10 is shown in Figs. 4 and 5. The modified last 55 is provided with a toe part 56 and a heel part 57 which are hinged together at or near the ball portion of the foot by a hinged joint 58, which is constructed and operated in the same manner as described Yin reference to Figs. 2 and 3. This last is provided with a recess 59 in its bottom surface for the reception of an arch support 60, such as shown in crosssection in Fig. 5. In this modification it will be noted that the plane of the periphery 61 of the convex bottom 62 of the last is cut by the depression 59 formed for the arch support 60. In this case, and others concerning the azaasaa application of a heel to a cast latex sole, the' plane of the periphery of the bottom of the last may be cut at the longitudinal arch and in rear of such area to accommodate such constructions, but the plane of the periphery 61 of the bottom of the toe part of the last will remain as shown in Fig. 5, and such plane 61 of the toe part 56 must be arranged parallel to the liquid level 63 of the casting material in the mold cavity 64 in order to form a uniform thickness of the cast sole and uniform height of foxing thereon around the outer periphery of the toe part of the cast sole.

As shown in Fig. 5, the arch support 60 is placed in the recess 59, and the shoe upper 65 is lasted on the last 55 over a moldable, heat curable, perforated insole 66, which is placed between the arch support 60 and the outsole to be cast thereon. The same type of insole may be used in the shoe made in accordance with Figs. 1 to 3, heretofore described. The perforations 67 in the insole 66 are provided to permit the escape of any air or gas which may be trapped between the top surface ofthe liquid latex and insole.

After the shoe upper 65 is lasted over the insole 66 on the last 55 as shown in Fig. 5, the last 55 is placed on the jig as shown in Fig. 1 and dipped into the mold 68 containing the liquid casting material, which forms the outsole 69 thereon. From this point on the shoe and sole is treated in the same manner as described in reference to Figs. l to 3 of the drawings.

As shown in Fig. 6, a midsole 70 may be incorporated in the shoe 71, as shown in the longitudinal cross-section of a toe portion of the shoe. Such shoe may be built up on a last having a pivoted toe part, as heretofore described, or on a solid last, as described in the aforesaid prior application, depending upon whether or not it is desired to incorporate toe spring in the shoe. As shown in Fig. 6, the shoe upper 72 is lasted over an insole 73 comprising an under layer of sponge rubber 74 bonded to a top layer of fabric 75. The midsole 70 is then applied to the bottom of the lasted upper 72, and it comprises a top layer of sponge rubber 76, and a bottom layer 77 of perforated rag stock. The perforated layer 77 is adhered to the sponge rubber layer 76 and this composite midsole is adhered to the bottom of the lasted shoe upper. The outsole 78 is then cast over the midsole 70 and onto the shoe upper 72, as heretofore described. The sponge rubber layers 74 of the

insole

73 and 76 of the midsole 70 are cured or vulcanized before they are incorporated in the shoe and are porous, soft and flexible, whereas the layer of rag stock 77 is uncured, moldable and plastic, but is adapted to be vulcanized to cause it to retain its shape and become stiff and resistant to bending. The vulcanizable layer 77 is cured simultaneously with the cure of the outsole 78, as heretofore described, with, or without toe spring being imparted to the shoe.

As shown in this modified form of shoe, it is desirable to use a relatively exible soft insole 73 to complement the softness of the sponge rubber layer 76 in the midsole, and place the bottom layer 77 of the midsole 70 adjacent to the outsole 78 so that the rag stock layer 77 will become relatively stiff when vulcanized and will be more effective in resisting the shrinkage of the cast outsole, and also so that it will be more elective in permitting any air that may be trapped between the upper surface of the liquid casting material and the midsole to escape through the perforatons 79 of the bottom layer 77 of the midsole 70 and pass upwardly through the porous sponge rubber layers 76 and 74 of the midsole 76 and insole 73 during the vulcanization of the outsole 78. Blisters, and air cells are thus prevented from being formed in the cast outsole, and between the several layers of material in the bottom of the shoe.

The sponge rubber layer 76 of the midsole and 73 ot the insole is cured prior to being assembled in the shoe in order to prevent expansion and the formation of gases `during the cure of the outsole 78 and bottom stiffening layer 77 of the midsole, and from being deformed.

My invention has been described more or less in detail, but it will be understood that changes may be made therein without departing from the spirit of this invention or the scope of the appended claims, and I intend to be limited only by thescope of the claims.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

l. A method of castinga llexible sole from a liquid casting material onto the bottom of a shoe upper and producing toe spring in the cast sole, comprising the steps of placing an upper on a last having a toe part adapted to be pivoted on a `heel part from a sole casting position to a toe sprung position, pouring a casting liquid into a sole forming mold, dipping the bottom of said upper into thereby prevent the' outsole said liquid while said toe part is pivoted to its casting position and until said liquid solidies into a sole on said upper, removing said last with said upper and 'sole thereon from lsaid mold, pivoting saidr toe part of said last to its toe sprung position, and curing said sole in said toe sprung position. 1

2. A method of casting a flexible sole from a gelable liquid rubber latex onto the bottom of a lasted shoe upper and producing toe spring in the cast sole, comprising the steps of lasting the upper on a last having a toe part provided with a bottom periphery lying in a plane and adapted to be pivoted on a heel part from a sole casting position to a toe sprung position, pouring said gelable liquid latex into a sole forming mold, dipping said lasted upper bottom into said liquid while said toe part is pivoted to its casting position, maintaining said plane of said periphery of the bottom of said toe part of said last parallel with the liquid level of said latex until said liquid solidies into a sole on said upper, removing said last with said upper and sole thereon from said mold, pivoting said toe part of said last to its toe sprung position, and curing said sole in said toe sprung position.

3. A method of casting a flexible outsole on the bottom of a shoe upper and producing toe spring therein comprising the steps of applying a shoe upper to a last having a toe part provided with al bottom periphery lying in a plane and adapted to be pivoted on a heel part from a sole casting position to a toe sprung position, aflxing a layer of moldable heat curable material to the bottom of said upper, pouring liquid casting material into an open sole forming mold, dipping the bottom of said upper into said liquid while said toe part of said last is pivoted to its casting position, maintaining said plane of said periphery of the bottom of said toe part of said last parallel to the liquid level of said casting liquid until said liquid solidifies into an outsole on said upper, removing said last and said upper with said attached outsole from said mold, pivoting said toe part of said last to its toe sprung position, and heat curing said outsole and simultaneously heat curing said moldable layer until suicient stiffness is imparted thereto to retain its toe sprung shape.

4. A method of casting a llexible outsole from gelable liquid rubber latex onto the bottom of a lasted shoe upper and producing toe spring in the cast sole, comprising the steps of lasting the upper over a moldable heat curable insole on a last having a toe part provided with a bottom periphery lying in a plane and adapted to be pivoted at the ball portion of said last on a heel part of said last from a sole casting position to a toe sprung position, pouring said gelable liquid latex into an open sole forming mold, dipping said lasted upper bottom into said liquid while said toe part is pivoted to its casting position, maintaining said plane of said periphery of the bottom of said toe part of said last parallel with the liquid level of said latex until said liquid solidifies into an outsole on said upper, removing said last and said upper with said attached outsole thereon from said mold, pivoting said toe part to its toe sprung position, and curin said insole and outsole.

5. A method o'f making a shoe having a flexible cast outsole thereon Vcomprising the steps of applying a shoe upper to a last, applying a midsole comprising a top layer of soft ilexible porous material and a bottom layer of moldable heat curable perforated material to the bottom of said upper, casting a heat curable ilexible outsole over said midsole and onto said upper, heat curing said bottom layer of said midsole and said outsole, and expelling gases through said perforated and porous layers.

6. A method of making a shoe having a flexible cast outsole thereon comprising the steps of applying a shoe upper to a last having a toe part provided with a bottom periphery lying in a plane and adapted to be pivoted on a heel part from a sole casting position to a toe sprung position, applying a midsole comprising a top layer of soft exible porous material and a bottom layer of moldable heat-curable perforated material to the bottom of said upper, pouring gelable liquid latex into a sole forming mold, dipping the bottom of said upper into said liquid while said toe part of said last is pivoted to its casting position, maintaining said plane of said periphery of the bottom of said toe part of said last parallel with the liquid level of said latex until said liquid solidies intoV al1-outsole on said upper, removing said last and said upper with said outsole attached thereto from said mold, pivoting said toepart to its toe sprung position, and heat curing said outsole `and simultaneouslyl heat curing said moldable layer until sufficient stiffness is imparted thereto to resist `deformation as a result of the shrinkage of said outsole.

References Cited in the file of this patent UNITED STATES PATENTS 13,073 Wimley June 12, 1855 601,621 Tyler Mar. 29, 1898 830,168 Pierce Sept. 4, 1906 927,287 Saunders July 6, 1909 1,989,853 Finn Feb. 5, 1935 2,348,628 Jayne May 9, 1944 2,638,633 Root May 19, 1953