US 3705433 A
A foot form for injection molding string lasted footwear in which the heel portion of the form is movable between foreshortened, intermediate, and extended conditions, with means for locking the form in such conditions. The shoemaking method includes the steps of mounting a loose shoe upper having a lasting string in the margin on the form in foreshortened condition, tensioning the string to partially last the upper on the foreshortened last, moving the heel portion of the form to extended condition to fully tension the string and last the upper, and injection molding a shoe bottom on the lasted upper.
Description (OCR text may contain errors)
United States Patent Stoddard et a1. Dec. 12, 1972 54] FOOT FORM AND SHOEMAKING 2,932,064 4/1960 Farmer et al. ..12/13s R METHOD 3,091,813 6/1963 Walker 3,203,050 8/1965 Hoffman ..l2/123  Inventors: Ivan Stoddard, Sutton-m-Ashfield;
Terence Brought, y- Primary Examiner-Patrick D. Lawson Ashfield, both of England Attorney-Richard A. Wise, Richard B. Megley and [7 3] Assignee: USM Corporation, Flemington, NJ. vmcem  Filed: March 8, 1971  ABSTRACT  Appl. No.: 122,082 A foot form for injection molding string lasted footwear in which the heel portion of the form is movable between foreshortened, intermediate, and extended  Apphcafion Pmmty Dam conditions, with means for locking the form in such March 6, 1970 Great Britain ..l0,773/70 The smemaking methd.includes.the 1 of mounting a loose shoe upper having a lasting strmg in thetmargin on the form in foreshortened condition, [g2] (g1. R ten-smiling the string 0 partially last the upper on the 1 l1 ..A d /00 foreshonened last, moving the heel portion of the  Fleld Search 135 135 133 R form to extended condition to fully tension the string and last the upper, and injection molding a shoe bot-  References Cited tom on the lasted upper.
UNITED STATES PATENTS 3 Claims, 7 Drawing Figures Pmmmuamma 3.705.433 SHEEI 1 [IF 4 [nvenfors Ivan Stoddard Terence D. Brouyhfon By their After-n67 7% 0. W
PATENTED E 2 I97? 3.705.433
SHEET 2 OF 4 I 1 FOOT FORM AND SHOEMAKING METHOD BACKGROUND OF THE INVENTION form of a shoe bottom unit. A fluid molding material is then injected into the cavity to provide, on solidification, a shoe bottom molded to the upper assembly. r
I One of the difficulties of the method involves the string lasting of the upper assembly. In general, this is carried out by hand, and requires that an operator exert a considerable tension in the string, especially when the upper of the upper assembly isof leather, to draw the lasting margin of the upper assembly partially over the bottom of the foot forrn. Often the operator must wear heavy gloves to minimize damage to hishands. Accordingly, it is ageneral objectof this invention to provide an improved method of shoemaking which involves considerably less manual effort by use of a novel method of shoemaking and a novel foot form usedin carrying out the method. In accordance with one feature of the invention the foot form comprises a body portion having a shape corresponding generally to that of the forepart of a shoe, and a heel portion mounted on the body portion for movement relative thereto between an extended position, in which the foot form is at its maximum length, and a foreshortened position in which a shoe upper assembly may be conveniently mounted on or removed from the foot'form. The foot form also includes means to secure the heel portion against movement relative to the body portion in an in termediate foreshortened position (in which the foot form is in an ideal condition for mounting' a loose upper) between the extended and foreshortened positions. Such means is provided by a locking member mounted in the heel portion and releasably engagable in a recess of the body portion. The body portion is provided with two further recesses, one either side of said recess, and the locking member is releasably engagable in said further recesses to secure the heel portion against movement relative to the body portion in said extended and foreshortened positions. The foot form" may be mounted in an injection molding machine similar to the machine described by way of example in US. Pat. No. 3,358,333 for cooperation with a sole mold assembly adapted to provide a mold cavity the form of a shoe bottom unit. Such a machine also includes'an injection mechanism adapted to inject a fluid plastics material into the mold cavity.
According to a further feature, the foot form is used in a novel method of shoemaking using a shoe upper assembly prepared for a string lasting operation comprisof the foot form and the string is tied. The heel portion of the foot form is then moved to its extended position, causing a lengthening of the foot form and thereby an increase in the tension of the string to complete the string lasting of the upper assembly. It will be apthe increasein the tension with which the upper assembly is string lasted by movement of the foot form from its intermediate to its extended condition allows the operator to string last the upper assembly with a lesser tension than would be required in presently known methods allowing an upper assembly to be string lasted in a shorter time with less damage to the the lasted upper is moved into cooperative relation ing a string sewn loosely around the inner edge of the the upper margin is tensioned to draw the upper assembly around the foot form with the lasting margin of the upper assembly extending partially over the bottom with the sole mold assembly of the injection molding machine so the foot form and the lasted upper assembly thereon close the shoe bottom forming mold cavity. Fluid plastic material is injected into themold cavity and provides, on solidification, a shoe bottom molded to the upper assembly.
The above and other of the various objects and several features of this invention will become clear from the following description, to be read with reference to the drawings, of the illustrative foot formand of the illustrative method of shoemaking. It will be appreciated that both the foot form and the method have been selected to illustrate the invention by way of example only and not by way of limitation thereof.
In the drawings:
FIG. 1 is a side view showing the illustrative foot form in an extended condition, part of the foot form being broken away to shoe locking mechanism thereof,
part of a heel portion of the foot form being shown (in chaindot) in intermediate and foreshortened positions. FIG. 2 is a sectional view, taken along the line II-II of FIG. 1, of part of the illustrative foot form.
FIGS. 3 5 are perspective views showing various positions of the heel portion of the foot form in the practice of the illustrative shoemaking method.
FIG. 6 shows a side elevation of the foot form having a string lasted shoe thereon with the foot form moved into cooperative relation with a shoe bottom mold assembly, and
FIG. 7 is a perspective view of the foot form in foreshortened condition and a completed shoe being removed therefrom.
The illustrative foot form is adapted to form part of an injection molding machine similar to the machine described by way of example in US. Pat. No. 3,358,333. Such a machine includes a sole mold assembly 2 (FIG. 6) adapted to provide a mold cavity 3 the form of a shoe bottom unit and an injection mechanism (not shown' herein) adapted to inject molten p.v.c. into the mold cavity through a passage 4.- A foot form carrier 5 is mounted above the sole mold assembly for movement toward and away from the mold cavity. The illustrative foot form 6 is releasably secured to the carrier and rotatably mounted thereon for movement between an elevated position in which the bottom of the foot form faces an operator standing at the machine, as generally seen in FIGS. 3 5, and an operative position in which the bottom of the foot form faces the mold cavity of the sole mold assembly as generally seen in FIG. 6.
The foot form 6 comprises a plate 10 adapted to be secured to the carrier of the injection molding machine and having a body portion 12 (FIG. 1) extending therefrom and including a forepart portion 14 of a shape corresponding generally to that of the forepart of a shoe. The body portion is provided with a convex arcuate surface 16 extending from adjacent the plate to a bottom surface of the forepart portion 14. Extending through the arcuate surface are two slots, a first slot 18 closer to the plate 10 than a second slot 20. Secured in a shallow groove extending through the arcuate surface is a curved plate 22 of the body portion provided with three recesses, a first recess 24 closest theplate, a second central recess 26 and a third recess 28. The first and second recesses both overlie the first slot 18 and the third recess overlies the second slot 20. Extending through the arcuate surface 16 from the bottom surface 15 toward the second slot is a dove-tail slot 17 (FIG. 2). The foot form also includes a heel portion 30 of a shape corresponding generally to that of the backpart of a shoe and mounted on the body portion for movement relative thereto. A concave arcuate surface 32 of the heel portion of a curvature equal to that of the surface 16 of the body portion 12 extends from a bottom surface 33 of the heel portion, and a dove-tail 34 extends from said surface 32 and is received in the dove-tail slot 17 of the forepart portion 12.
The heel portion 30 of the footform is movable between an extended condition (FIGS. 1 and 5), an intermediate condition (FIG. 3), and a foreshortened condition (FIG. 7). In the foreshortened condition, the foot form provides the shortest length dimension (see chain-dot line F, FIG. 1) suitable for easy removal of a completed shoe as illustrated in FIG. 7. In the extended condition, the foot form presents its greatest length dimension, suitable for final lasting of a shoe upper as seen in FIG. 5 as well as for holding the lasted shoe during a shoe bottoming operation as seen in FIG. 6. In its intermediate condition, the length of the foot form is somewhat foreshortened as indicated by the chain-dot line I in FIG. 1, and the unlasted upper U is easily placed on the form as seen in FIG. 3 and initially tensioned as seen in FIG. 4. By fully extending the form from the intermediate condition, the upper is fully tensioned to the condition seen in FIG. 5. The heel portion 30 may be locked in its various conditions by means of a locking mechanism 50, best seen in FIG. 1. To this end a rodlike locking member 52 is slidably mounted in a bore 36 in the heel portion. The rod is spring biased toward the plate 22 of the body portion 12 so as to be received by any one of the recesses 24, 26 and 28. By pulling a handle 54 on the locking rod, the rod may be withdrawn from one of the recesses and the heel portion 30 moved to another of its conditions with the rod being received in an appropriate recess for locking.
In carrying out the method if shoemaking, an injection molding machine such as that disclosed in said patent is provided with the above described foot form secured to the carrier thereof. By rotation of the foot form relative to the carrier the foot form is moved to its elevated position and by movement of the handle 54 the foot forrnjs moved to its foreshortened or its intermediate condition. A shoe upper assembly prepared for a string lasting operation and comprising an upper U and a string S sewn loosely around the inner edge of the lasting margin of the upper is mounted on the foot form as seen in FIG. 3. If in its fully foreshortened condition, the foot form is moved to its intermediate condition by pulling the handle 54 outwardly to withdraw the locking member 52 from the recess 28 and move the heel portion 30 until the locking member is located in the recess 26. The string of the upper is then tensioned by the operator to draw the upper around the foot form with the lasting margin of the upper extending partially over the bottom surfaces of the foot form, and the string is tied as seen in FIG. 4. The heel portion 30 is then moved to its fully extended condition as seen in FIG. 5, locking member 52 first being withdrawn from the recess 26 and inserted in the recess 24. This last fully extending movement of the heel portion 30 increases the length of the foot form and increases the tension in the string of the upper assembly to complete a string lasting of the upper.
The foot form is then rotated to its lower operative position, and the carrier moves the foot form toward the mold cavity into cooperation with the sole mold assembly, the foot form and upper assembly thereon closing the mold cavity as seen in FIG. 6. The injection mechanism of the machine is operated to fill the mold cavity with molten plastic material which, on solidification, provides a shoe bottom molded to the upper assembly.
It will be appreciated that the increase in the tension with which the upper assembly is string lasted on movement of the foot form from its intermediate to its foreshortened condition depends, among other factors, on the position of the recess 26. It will be appreciated further that, in the illustrative foot form, the plate 22 may be readily replaced by a similar plate provided with a central recess in a different position, thereby changing the degree of increase of said tension on movement of the foot form from its intermediate to its foreshortened condition.
Having thus described our invention what we claim as new and'desire to secure by Letters Patent of the United States is:
1. A foot form for lasting shoes including a forepart portion having a guideway, a heel portion mounted on the guideway for sliding movement between an extended position in which the foot form is at its maximum length and a foreshortened position, said heel portion having a handle by which the heel portion is moved between said positions, and means for locking said heel portion alternately in said positions and in an intermediate foreshortened position.
2. A foot form according to claim 1 in which the guideway comprises an arcuate dove-tail connection between the forepart portion and the heel portion.
3. A foot form according to claim 1 in which the handle is formed on the outer end of a rod mounted in said heel portion for axial movement into and out of alternate engagement with apertures in the forepart portion for locking the heel portion alternately in one of said positions.
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