US 3186113 A
Description (OCR text may contain errors)
June 1, 1965 M.- R. RADCLIFFE ETAL ,186,11
ATTACHMENT OF SHOE INSOLES TO LASTS Filed Aug. 30, 1962 2 Sheets-Sheet l [nuentars Mi/zon i3. Radcliffe Donald L. Bray .By their Afforney J1me 1965 M. R. RADCLIFFE ETAL 3,186,113
ATTACHMENT OF SHOE INSOLES TO LASTS 2 Sheets-Sheet 2 Filed Aug. 30, 1962 "Mu V I I L United States Patent ATTACHMENT 0F SHOE INSOLES T0 LASTS Milton R. Radcliife, Marblehead, and Donald L. Bray,
Beverly, Mass., assignors to United Shoe Machinery Corporation, Boston, Mass, a corporation of New .Iersey Filed Aug. 30, 1962, Ser. No. 220,391 5 Claims. (Cl. 336-43) The present invention relates to improvements in shoemaking operations and more particularly to means and methods for obtaining shoemaking assemblies which include insoles positioned onto the bottoms of shoe lasts.
Generally, the first step in lasting shoes includes positioning an insole onto the bottom of a shoe last in order to obtain a shoemaking assembly on which to carry out the remaining lasting steps. To be done properly, this positioning should be done both accurately and securely. Otherwise, in practicing the lasting steps which follow such as toe lasting, side lasting, etc. and other steps such as edge trimming and the like, it becomes difiicult if not impossible to obtain a lasted shoe which is strongly constructed and one in which all of the parts are so aligned, shaped and unified as to contribute to the shoe a clean molded appearance.
Improper positioning of an insole onto a last bottom which can lead to shoemaking difiiculties usually takes one or both of two forms. The first of these is misplacement which reflects inaccuracy in initially positioning the insole onto the last bottom. The second is displacement, which occurs during the lasting steps which follow initial positioning, and, is reflective of insecure positioning of the insole onto the last bottom.
The lasting steps which immediately following positioning of the insole onto the last bottom are particularly critical with respect to displacement. At this point heavy stresses of various kinds are applied through the agency of wipers, clamps, pulling arms and the like, to the shoe assembly, in order to shape, align and unify the various shoe parts into a shoe whose shape conforms to that of the last or form.
A number of expedients have been proposed for positioning an insole onto a last bottom. The most common of these is the use of temporary tacks. Others which have been used to a significant extent include the use of various registering means, such as retractable jig pins located in a last bottom which cooperate with complementary jig holes located in an insole, as well as still others of a similar operating order. These have all been more or less designed as alternatives for the practice of using temporary tacks.
In spite of the shortcomings surrounding the use of temporary tacks; they have to be pulled before removal of the shoe from the last, nevertheless, their use in positioning insoles onto last bottoms is still next to universal. This has resulted because many of the expedients proposed as alternatives are expensive in their production, use and maintenance. Many of the others remaining then fail to give positioning which remains accurate and se curely positioned throughout the lasting operation.
It is an object of the present invention to present shoemaking means and methods for providing shoemaking assemblies in which shoe insoles may be accurately and securely positioned onto the bottoms of shoe lasts.
It is another object of this invention to provide shoe assemblies as above which are capable of maintaining accurate and secure positioning between insoles and shoe last bottoms throughout the lasting operation.
It is another object of this invention to provide the shoemaking assemblies as above which serve as references from which to last shoes which are strongly constructed ,and in which all of the parts are so aligned, shaped and Patented June 1, 1965 unified as to contribute shoes having clean molded appearances.
It is another object of this invention to provide shoemaking assemblies which can be conveniently disengaged after the lasting operations have been carried out to allow for easy removal of the lasted shoes from the lasts.
It is another object of this invention to provide shoemaking assemblies as above which are simple and economical in their production as well as in their use in lasting operations.
These and other objects of the present invention are attained in particular shoe insoles; in shoemaking assemblies in which the particular shoe insoles are combined with shoe lasts having cooperating features; and, in methods of obtaining the shoemaking assemblies. The shoe insoles of this invention include heel seat portions having integrated upwardly projecting registration pins molded from polymeric material. In order to coordinate these shoe insoles with shoe lasts in such a manner as to obtain shoemaking assemblies in which the shoe insoles are accurately and securely positioned in predetermined relationship onto the bottoms of the lasts, the lasts have registration holes located at the bottoms thereof. The registration pins are located on the insoles in correspondingly disposed relationship to the registration holes located at the bottoms of the lasts. In obtaining the shoemaking assemblies referred to, the registration pins on the shoe insoles are introduced into the correspondingly disposed registration holes located at the bottoms of the shoe lasts.
By practice of the present invention, shoe assemblies in which shoe insoles are accurately and securely positioned onto the bottoms of shoe lasts are obtained. The lasting operations which follow on the shoemaking assemblies so obtained are facilitated in ease of operation because the probability of the insoles being misplaced or becoming displaced during lasting is greatly minimized. The final result of this is the production of well-constructed shoes. The uppers of shoes so produced evidence a uniformly clean molded appearance; this includes back parts of the uppers as well, where a clean molded line from top line through the heel is obtained. This is of particular note in that back parts of shoes represent an area where a great deal of difficulty has previously been encountered.
The present invention is simple in its practice. Obtaining the necessary corresponding disposition of registration pins and registration holes in the insoles and lasts, respectively, can involve use of a master or template in locating both. The registration holes may be provided at the bottoms of the lasts by a simple drilling process. In providing the registration pins on the shoe insoles, the same master or template is used in making mold parts, for instance, a mold cover which includes secondary mold cavities in which to mold the registration pins simultaneously and integrally with molding at least the heel seat portions of the insoles.
Because in the shoe assemblies of the invention the bottoms of the lasts are provided with registration holes rather than jig pins, lugs or the like, no special care is required in handling these lasts during the shoemaking operation. Due to the critical nature of the registration which is necessary for proper positioning, with insoles, lasts having jig pins very often become crippled, either through damage or misalignment of the pins, with the rough handling to which lasts are ordinarily subjected in shoemaking operations.
Practice of the present invention also leads to eliminating operational steps which are ordinarily practiced in removing a lasted shoe, and, similarly disengaging the insole of the lasted shoe from the last, after lasting. For instance, in practicing this invention there is no necessity 3 for practicing various tack pulling steps as are necessary when temporary tracks are used to position the insoles on the last bottoms.
The following drawings are included for the purpose of further illustrating the invention in which:
FIG. 1 is a diagrammatic view in top perspective showing a shoe insole having a heel portion and an integrated pair of registration pins each molded from a synthetic polymeric material;
FIG. 2 is a diagrammatic view in bottom perspective showing a shoe last having a pair of registration holes located in the heel plate;
FIG. 3 is a diagrammatic view in side elevation with parts broken away showing a shoemaking assembly in inverted position constituted of a shoe insole positioned on a shoe last; and
FIG. 4 is a diagrammatic view in side elevation with parts broken away showing a shoe and last again in inverted position and after the lasting operation has been completed with the back part of the last disengaged from the heel seat portion of the insole of the shoe.
In the drawings, a single embodiment of the present invention is shown by way of illustration. This will now be described. An insole 10 as shown in FIG. 1 may constitute a forepart 12, arch section 14 and a heel seat portion 16. Heel seat portion 16 is molded to shape from a polymeric material such as a foamable thermosetting polyurethane. Forepart 12 and arch section 14 are a single shape, die cut from a sheet of composition material and attached to or unitized with heel seat portion 16 with molding of the latter. The entire insole 10 may be molded to shape from synthetic polymeric material if desired. It is also possible, in a manner not shown, to include a shank piece into a molded arc section 14 during molding.
A pair of integrally molded registration pins 18 and 20 are shown projecting upwardly from the top or upper side of heel seat portion 16. By integrally molded is meant that registration pins 18 and 20 are integrated with heel seat portion 16 by or during molding of the latter, and that a polymeric material is used as the molding material.
Registration pins 18 and 20 as shown are two in number, however, the number can range from a single pin which is profiled to contribute accurate and stably secure positioning both longitudinally and laterally of the last, to a number of registration pins accomplishing the same end. Actually two registration pins as shown, perform this purpose suitably while allowing for each pin to have a simple yet conveniently obtainable cross section, for example, circular, which admits to close molding, fitting and assembly tolerances. Registration pins 13 and 20 which are two in number and which have diameters and projections or heights both as small as inch, have been found to give accurate and secure positioning of the type desired. Variations from these measurements can also be practiced if desired.
It is recommended that a registration pin, when one is used, or registration pins when more than one is used, be located consistently in longitudinal and lateral alignment in relation to the center line of the insole. This serves to equalize stresses applied to the registration pins during lasting. In a preferred embodiment each of registration pins 18 and 20 is tapered at its projecting end to facilitate its assembly, and later, disengagement from the last. In addition, for convenience in disengaging insoles from the last after lasting, registration pins 18 and are both located in the heel seat portion 16 of insole 10. However, it is possible, but not necessary, to position at least some or additional registration pins at other locations on the insole.
Registration pins 18 and 20 are located on the top surface of insole 10 in correspondingly disposed relationship to registration holes 22 and 24 located at the bottom of a shoe last 26 as shown in FIG. 2. More specifically, the registration holes are shown entering the bottom of last 26 through heel plate 28 which is secured by a number of screws 30 to the bottom of the heel part 32 of last 26. Heel part 32 of last 26 is held in limited pivotable relationship to forepart 34 by means of a hinge link, not shown, which is fastened in the interior of the last 26 by means of pins 36 and 38.
Insole 10 is positioned securely and accurately onto last 26 to obtain the shoemaking assembly shown in FIG. 3. This calls for introducing registration pins 18 and 20 of insole 10 into registration holes 22 and 24 respectively of last 26. Positioning of the desired type is further facilitated if the top surface of insole 10, particularly at the heel seat portion 16, is contoured in a concave manner complementing the bottom surface of last 26.
After positioning insole 10 onto last 26 in the manner described, the various lasting operations such as pulling over, heel lasting, toe lasting and side lasting, also the operations of edge trimming, soling and heeling may be carried out with positional reference to both last 26 and insole 14 to obtain a lasted shoe 40 as shown in FIG. 4.
On removing shoe 40 from last 26, last 26 is broken at the hinge causing back part 32 to pivot downwardly, as shown, and away from insole 10. This causes registration pins 18 and 20 to become disengaged from registration holes 22 and 24 respectively to where they will not interfere with removal of shoe 40 from last 26, by simple slip or slide action. Following removal of shoe 40 from last 26, the projecting parts of registration pins 13 and 20 can be effectively eliminated by any one of a number of convenient methods such as cutting or abrading the pins down to flush with the upper surface of insole 10. As a result there are no holes to be filled in nor tacks to be removed from the insole as is quite often the case using the positioning expedients presently known.
The insoles of the present invention have at least their heel seat portions as well as the integrated registration pins molded from a polymeric material which in molded form has sufficient strength to withstand the heavy stresses to which these parts are subjected with lasting. In addition, in molded form the polymeric material should exhibit those strength properties which are desirably present during other shoemaking operations as well as those properties which contribute to desirable shoe wearing. During lasting, stresses of 2000 pounds and greater are commonly applied to shoe assemblies by action of the wipers, etc. This is for the purpose of pulling various shoe parts into shaped conformation with the last. Under these stresses the registration pins and similarly the material from which they are molded should not deform as to allow the insole to become significantly displaced or misaligned with relation to the last. If this occurs a poorly constructed shoe is the result. It is recommended that the registration pins and insoles be molded from polyurethanes, polyepoxides and polyesters and similar materials in order to obtain this performance. Other polymeric materials which may be used include high impact polystyrenes, which have butadiene and/or acrylonitrile in polymerized form either copolymerized or blended with polystyrene; also olefinic polymers and copolymers such as those of ethylene and propylene which can be adapted to perform as indicated. Combination of the various polymeric materials can be used.
The registration pins and heel part of the insole may be molded entirely of polymeric material. However it is more probable to include various fillers, colorants and the like. It is also possible to utilize the polymeric material in such a manner as to have the molded insole take the identity of a laminate, with the polymeric material acting as a binder. Other similar variations can be practiced in molding the insole and integrated registration pins from the polymeric material.
The polymeric materials preferred for use in providing the insoles of the present invention are the polyurethanes. Polyurethanes, as differentiated from most synthetic polymeric materials and particularly thermoplastic addition type polymeric materials are easily compounded as not to creep significantly or lose their dimensions when subjected to stresses of the magnitude encountered in shoe lasting. Simultaneously they are not so brittle as to snap .Off under these stresses. In addition to that it is desirable that the polymeric material from which the heel seat is made be such that it be resistant to splitting when nailed, and, have nail holding ability. This allows heels to be nailed to the shoes. Due to this, polyurethane foam and preferably those having densities of to 50 lbs/ft. are recommended with those having a foam density range of 25 to 40 lbs ./ft. being particularly recommended. Under conditions of wear, the insoles desirably have the capacity to flex while at the same time being tough, strong and have some resiliency in order to contribute comfort to the wearer. This too is satisfied by the use of semi-rigid polyurethane foams in the heel portions of insoles. Again, the thermosetting polyurethane foams are also desirable because of their relatively light weight, adding to shoe wearing comfort.
The use of polyurethanes as molding compounds also has the advantage that it allows registration pins which are of small diameter and few in number to be used. Neither is it necessary to mold the registration pins around dowels or other strengthening members as may be necessary when the registration pins are molded from many thermoplastic addition type synthetic polymers and similar materials. The use of dowels, etc. is extremely difficult to accomplish satisfactorily from the standpoint of positioning and in addition it adds difficulty and expense to the step of removing the registration pins from the insole which is carried out after lasting. Polyurethane materials are readily available, and various compositions and processes are used in their production and use. The following indicates one manner of producing a semirigid foamed polyurethane which is etfective for molding the insoles of the present invention. An excess of polyisocyanate, such as toluene diisocyanate, is reacted with an organic compound having at least two reactive hydrogen groups, for instance castor oil, to provide a polyester urethane having terminal isocyanate groups. This is an intermediate product which is commonly referred to as a prepolymer. A polyol such as a pentol obtained from reacting propylene oxide with diethylene triamine, a catalyst, such as dibutyl tin dilaurate, and water are mixed with the prepolymer to react further to a final semi-rigid molded foam. The water reacts with the terminal isocyanate groups of the prepolymer to bring about crosslinking and production of carbon dioxide. Cross linking brings about solidification of the reacting mass, while the carbon dioxide serves to act as an expanding agent in the reacting mass.
The mixture of prepolymer, polyol, catalyst and water is charged into a mold having a mold cavity, complementing at least the heel seat portion of the insole and secondary cavities complementing the registration pins. The cross-linking reaction is allowed to take place there to obtain an insole having a molded heel seat portion and integral molded registration pins of semi-rigid polyure thane foam. The molds and molding processes which may be used are described with more detail in my copending application Serial No. 220,505, filed of even date.
The following example is included for the purpose of further describing the invention. Where parts are menti-oned parts by weight are intended unless otherwise described.
Example I (A) Molding charge preparation-A prepolymer is prepared by reacting 900 parts of castor oil with 525 parts of toluene diisocyanate. The reaction is carried out by heating the mass at 80 C. for a period of 120 minutes.
A reactant addition is made up by mixing 130 parts of a pentol, which is a condensation product of diethylene triamine and propylene oxide, with parts of castor oil, 2 parts of tetramethyl butane diamine (catalyst), 1 part of dibutyl tin dilaurate (catalyst) and 1 part of water.
(B) Mold preparationz-The heel bottoms of a pair of plastic (ethylene-butene copolymer) lasts for ladies shoes are provided with pairs of holes inch in depth and diameter, spaced 1 /2 inches in longitudinal alignment on the center line of the last bottom. A contoured steel template is used for locating the holes. A pair of mold bodies are made from the plaster of Paris using the bottoms of the lasts to which insoles are attached for shaping the mold cavities. A polyethylene mold cavity liner which complements the shape of the entire bottom of the plastic lasts is then inserted in the mold cavities.
(C) Insole m0lding.An insole piece including a forepart and arch portion die cut as a single unit from latex bonded cardboard (0.060 inch thick), is positioned in the forward part of each ofthe lined molding cavities. A molding charge constituting 2 parts of prepolymer and 1 part of reactant addition, having a total weight of about 20 grams and in fluid form is then charged into each cavity, and the corresponding drilled plastic lasts matching in size those used to make the mold cavity are clamped in partially inserted position into the cavities. An exothermic reaction takes place in each case converting the fluid polyurethane charge to a semi-rigid polyurethane foam having a density of about 35 pounds per cubic foot. Time for reaction is about 15 minutes.
When the molds are opened insoles having pairs of registration pins corresponding to the holes in the bottom of the plastic lasts can be easily removed. The back parts of each of the insole, which are of semi-rigid foam, are strongly adhered to the inserted insole pieces.
(D) Lasting 0perati0n.-The same plastic lasts which are used in molding the insoles can be used to last a pair of shoes. The insoles are positioned on the lasts by inserting the registration pins of the insole into the registration holes located in the last bottoms. The shoemaking assemblies so obtained are each placed in a combined back part molding and heel seat lasting machine together with a corresponding prestitched upper. There the upper is shaped to fit the back part of the last by the wiping action of the pair of wipers exerting about 200 pounds per peripheral inch of heel seat wiped. Attachment of the upper to the insole is obtained through a ribbon of adhesive applied to the periphery of the heel seat portion of the insole. The partly lasted shoe is placed in a side laster, and later a toe laster, the toe laster again using a pair of wiper arms, where the remaining lasting steps are carried out. Thereafter an outsole is cemented on and a heel is nailed onto each of the shoes. Following that edge trimming and finishing of the shoes are carried out.
After finishing, the last is broken at the hinge and the shoes slipped off the last. The registration pins which have remained intact throughout the lasting operation are snipped off flush with the insole upper surface using blunt nosed snippers, and, a sock lining is cemented onto the insole.
When the shoes so obtained are examined, their back parts exhibit a clean molded appearance from top line through heel. All the parts of the shoes are extremely well aligned, not only with respect to one another but as to reproduction between shoes. When the shoes are worn it is noted that they hold up exceptionally well and are comfortable. Both properties can be attributed to the excellent alignment of the various parts of the shoes, and the high fidelity which the shoes show with the shape of the last, and, correspondingly the shape of the foot which the last is designed to reproduce.
It will thus be seen that the objects set forth above among those made apparent from the preceding description and efficiently attained, and since certain changes may be made in carrying out the above process, in the described insoles, shoemaking assemblies, and shoemaking methods set forth without departing from the scope of the invention it is intended that allrnatter contained in the above description and the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.
Having thus described our invention, what we claim as new and desire to secure by Letters Patent of the United States is:
1. Shoe insoles adapted to be accurately and securely positioned in predetermined relationship onto the bolttoms of shoe lasts having registration holes located at the bottoms thereof, the said insoles having at least the heel seat portions thereof formed of synthetic polymeric material and having integrally formed therewith registration pins projecting upwardly from the top surface thereof, the said registration pins being located on the top surface of the insole to be in correspondingly disposed relationship to the registration holes located at the bolttoms of the shoe lasts.
2. Shoe insoles according to claim 1 wherein the registration pins are two in number.
3. Shoe insoles according to claim 2 wherein the regis- 8 tration pins are located in longitudinal alignment relative to the center line of the insole.
4. Shoe insoles according to claim 2 wherein the registration pins are located in the heel seat portion of the insoles.
5. Shoe insoles according to claim 1 wherein the insole and the registration pins are molded polyurethane foam.
References Cited by the Examiner UNITED STATES PATENTS 456,677 7/91 McIntyre 3643 X 645,038 3/00 Lyons 12129.6 1,470,651 10/23 Stewart l2-l29.6 1,736,276 11/29 Pym 12129.6 1,899,057 2/33 Pym 12129.6 2,340,582 2/44 Cushman 12129.6
FOREIGN PATENTS 574,429 1/46 Great Britain.
JORDAN FRANKLIN, Primary Examiner.
FRANK J. COHEN, Examiner.