IL29684A - Process of forming a shoe upper - Google Patents

Description

Patents Form No. 3 PATENTS AND DESIGNS ORDINANCE.

SPECIFICATION..

"PROCESS OF FORMING A SHOE UPPER 1 / WE ' UKXOH- CARBIDE ...GQPvPOHASIOii a coloration of 270 Park Avenue, New York, State of New York, United States of America, do hereby declare the nature of this invention and in what manner the same is to be performed, to be particularly described aud ascertained in and by the following statement : - This invention relates to shoe-making and refers more particularly to the production of pre-formed uppers for shoes.

In the manufacture of shoes in volume, the shoes are made to fit, and are assembled on, a last, not a foot. Thus, a piece of leather or other material is cut to form a blank for an upper, the blank is placed on a last and deformed to fit the last and to provide inturned margins to which inner and outer soles may be attached. The lasting operation requires great skill and dexterity if done manually and complex machinery if done mechanically. Careful use of materials is necessary to avoid waste. Because of the nature of leather and recently introduced leather-like materials, once the blank is placed on the last it must be secured to it and remain on it for a period of time required for it to assume and retain the desired shape. This period may be of several days' duration for leather.

The lasting operation thus in addition to requiring highly skilled labor and/or complex and expensive machinery requires a large investment in lasts which are relatively expensive. Because the operation requires deformation of the material used, severe strain is placed on the material and frequentl undesirable defects such as wrinkles, tears , and splits are encountered in areas where the material is distorted, particularly at the feather edge of the last, that portion being the intersection of the upper and the sole portions of the last especially at the toe and heel. Such defects of course lead to scrapping of the shoe. Frequently they are not detected until the shoe is finished.

Although the shoe-making industry has devoted much processes, for the most part machines that have been developed and used commercially merely replace the hands of the skilled artisan with mechanical devices. The basic art of physically distorting a blank of shoe material to fit a last and maintaining the blank on the last until the material has taken on a more or less permanent desired deformation has remained the same.

There have been proposals for changes i this basic art from time to time. For example, in United States Patent 2,904,838 it is suggested that a pre-formed upper of thermoplastic sheet material may be produced in a cavity mold. According to this proposal a leather shoe upper of desired pattern is lasted and is then "unfolded" from the last and used to prepare a master pattern and a cavity mold in which the outer surfaces of the original upper are reproduced. The thermoplastic material is forced into the mold until it assumes the shape and pattern of the cavity. It is then removed and placed on a last for further operations to produce a shoe of thermoplastic material reproducing the exterior appearance of the original leather upper.

It should be noted that this disclosure requires as a starting point the lasting of a leather upper and that the distortions and deformations encountered in such operation are reproduced in the master pattern from which the cavity mold is prepared. These distortions and deformations are transferred to the preformed uppers and must be removed when the latter are lasted .

It is an object of the present invention to provide a process for producing a pre-formed shoe upper of leather or leather-like material avoiding conventional lasting techniques. Another distortion and which fits substantially without deformation a last for which t» is designed.

The invention comprises a process in which a male die in the form of a partial development of the outer surface contours of a shoe last is produced from the last and is used to form under pressure and heat a blank of leather or leatherlike material to produce a shoe upper which fits the original last without further deformation and without distortion. More specifically, the process of the invention comprises the steps of forming a removable, flexible integument upon a selected shoe last; slitting and removing the integument from the last; unfolding it and utilizing the inner surfaces of the material to produce by conventional precision casting methods a male die the surfaces of which are a partial development of the external contours of the last; and pressing the die against a blank of shoe upper material supported on a yieldable diaphragm until the blank substantially takes the shape of the die.

In the accompanying drawing which represents somewhat schematically the process of the invention: Fig. 1A is a top view of a shoe upper blank; Fig. IB is a similar view of a shoe upper blank formed by the process of the invention; Fig. 1C is a top view of a shoe upper blank and other components assembled for forming; Fig. 2 is a side view showing a shoe last immersed in a liquid bath of coating material; Fig. 3 is a rear view of the last after removal from the bath of Fig. 2; Fig. 5 is a plan view showing the unfolded coating taken from the last of Fig. 4 and supported in position for preparation of a die therefrom; Fig. 6 is a three-dimensional view of a male die having the partially developed surface of the last of Fig. 1; Fig. 7 shows a test of the surface of the die of Fig. 6 and Fig. 8 is a diagrammatic representation partially in section and part being broken away of apparatus utilizing the die of Fig. 6 to form a shoe upper.

Referring now to the drawing, in the process of the invention a shoe last 10 (Fig. 2) of desired size and shape is selected. The last may be of conventional construction and material, but its external surfaces should be nonporous. The selected last 10 is immersed, as shown, in a bath 12 of liquid which forms a tough, flexible, strippable integument on the last upon its removal from the bath. As illustrated in Fig. 2 a plurality of reinforcing fibers 14 is placed on the last 10, at least in the vamp area before the last is immersed in the bath.

Upon removal from the bath and solidification of the liquid, the last 10 is provided with an integument 16 as may be seen in Fig. 3. It is desirable that marginal portions 18, 20 .(Figs. 3 and 4) about the top of the last 10 and the feather edge thereof respectively have a thicker layer than other portions. This may be accomplished by separate application of coating material to the marginal portions in any convenient manner.

As shown in Fig. 3 the entire surface of the last 10 is coated at this point. Since the top portion 22 corresponds to . in the integument, suitably at the heel of the last as shown in Fig. 3 and the integument 16 can then be removed from the last 10 as illustrated in Fig. 4, the fibers 14 being embedded in the integument 16 and intimatel adjacent to the surface of the last 10.

The slit integument 16 removed from the last 10 is now placed in a suitable vessel 28 and is arranged in concave manner as shown for example in Fig. 5 with the surface that had been adjacent to the last uppermost to form a mold for making a plaster pattern reproducing that surface. By conventional precision casting technique a male die 30 (Fig. 6) may then be produced preferably of aluminum or light metal alloy from the plaster pattern. The external surface of the die 30 is a partial development of the surface portions of the last 10.

Before producing the metal male die and to make certain that the plaster pattern for the male die 30 is accurate, it is tested by placing it on a perforate support mounted on a suitable vacuum box 32 and placing a thermoplastic fabric material 34 over the surface of the pattern. When a vacuum is drawn and heat is applied, the fabric 34 will conform to the surface of the pattern. The portion of the material enveloping the pattern is then cut from the fabric, and the cut out portion is applied to the last 10. If the surface of the pattern provides an accurate partial development of the surface of the last 10, the fabric portion will fit the last perfectly.

A flat shoe upper blank 36 (Fig. lA) is now provided in conventional manner. The heel portions 38 of the blank 36 are now preferably temporarily secured together as by a s itcn^ a wire staple or a piece of adhesive tape, and the blank 36 is then placed with its inside surface uppermost on a yieldable diaphragm 40, suitably of synthetic rubber such as neoprene, which forms the top of a fluid-filled vessel 42.

The male die 30 is mounted in inverted position on a ram 44 which is arranged above the chamber 42.

The die 30 is now moved into contact with the blank 36, and pressure is applied to urge the blank 36 against the diaphragm 40. Movement of the diaphragm 40 is resisted by the fluid in the chamber 42 so that the blank 36 is squeezed between the die 30 and the diaphragm 40. Heat may be applied to the die 30 by heating means conventionally arranged therein. Heat and pressure are applied to the fluid in the chamber 42. Thus, heat and pressure may be applied to the blank for a time sufficient for it to assume and retain the. shape of the die 30. When this has occurred, the die is moved away, and the formed blank is removed from the diaphragm. Its appearance is represented in Fig. IB.

The formed blank is now ready for lasting. It may be placed easily on the last without distortion and without the application of any substantial force. The heel portions 38 may be stitched or otherwise secured together on the last and the finishing operation^ for the shoe begun immediately without the necessity for maintaining the upper on the last for any protracted holding time.

A particularly preferred manner of assembling a sole IIsrael patent to the upper is that described in the copending United—flt;ate» applica ion No» 27717y In another embodiment of the invention (Fig. 1C) other components of a shoe upper such as a liner 46, a box toe 48, or counter-forming parts 50, 50' all of conventional materials may be positioned appropriately on the blank 36 with conventional cements used in the shoe-making industry prior to deformation of the blank.

Since, as shown, the heel portion of the blank 36 is split, it is convenient to provide a pair of elements, 50, 50', one on each side of the heel portion, which will form a counter When the upper blank is placed on the last. Tests have shown that these components are securely adhered together during the forming step of the invention. When the pre-formed upper so prepared is placed on the last for finishing, little remains to be done to the upper.

As has been indicated, the process of the invention is suited to the use of conventional leather shoe components. ■ Counter and box toe components may be of conventional material, and conventional liner material may be used. Recently introduced synthetic shoe upper materials are characterized as being "poromeric" and may be handled like leather. A material of this type suited to use in the invention is that available commercially under the trade name "Corf m".

The integument-forming material used to coat the last in the process of the invention is suitably one which is a viscous fluid capable of solidifying into a tough film strippable from the last in one piece. Such materials are commercially available and are used for example to provide protective coatings on tools and firearms to be shipped or moderately elevated temperatures (about 400°F.) is a viscous fluid and which at room temperatures forms a tough, flexible, strippable film.

The reinforcing fibers 14 used in the process of the invention may be of any strong material such as glass, metal or synthetic or natural textile fibers not weakened by the temperature of the fluid in which the last is immersed. Suitable synthetic fibers include rayon and nylon, the latter being preferred Suitable natural fibers include linen and cotton. Since the function of the fibers is merely to prevent distortion of the integument when it is removed from the last, the composition of the fibers is not critical to the process. It is their physical properties that are important . Although individual fibers may be used, most conveniently a piece of woven fabric of appropriate size is employed simply by draping it over the last, tacking it or otherwise adhering it in place if desired before the last is immersed in the "peel coat" or film-forming fluid.

That the process of the invention is adapted to rapid repetitive production of pre-formed shoe uppers from leather and leather-like material has been demonstrated by many tests. In one such series of tests, upper blanks were cut in conventional manner from cowhide. The blanks were formed in the manner described above, the male die being heated to a temperature of about 360°F. while the fluid below the resilient diaphragm was heated to a temperature such that the diaphragm temperature was about 250°F. Forming was completed in tines as short as four (4) seconds at a hydraulic pressure below the diaphragm of less than 20 p.s.i. Experience has shown that when temperatures and pressure of these orders of magnitude are used, forming time should be not less than about four seconds.. If lower die temperatures, say about 300°F. are used, somewhat longer time may be required. Similar tests using blanks of synthetic poromeric material ("Corfam") demonstrated that they could be formed by the process of the invention but that somewhat higher temperatures and longer times than used for leather may be necessary.

Shoe upper blanks formed by the pocess of the invention when placed on the last from which the male die was produced fit the last perfectly without distortion and without the application of stretching or other force. Since they have been pre-forraed, it is not necessary that they remain on the last for longer than the time necessary to complete shoe finishing operations such as soling. Thus, the lasts can be used for assembling a great number of shoes in a given work period and no longer need be used as shoe formers ; Pressing the blank against the yieldable diaphragm also, it has been observed , tends to smooth out any wrinkles and thereby not only eliminates such defects but also tends to produce a polished surface on the side of the blank in contact with the diaphragm. Since in the process of the invention the die represents the "inside" surface of a shoe and the outside surface of the last, and it is pressed against the inside surface of the blank, perfect fit of the formed blank on the last is assured. Since no force is required to make the blank fit the last, the occurrence of tears, wrinkles and splits is minimized.

Thus, it will be seen that the invention makes possible the production of formed shoe uppers rapidly and substantially eliminates the old time-consuming lasting operation in the shoe-making art.

While the invention has been described with particular reference to the drawing which shows one style of shoe upper , it will be understood that the invention is not limited to the production of that style upper.

Claims (1)

1. unfolding the slit integument arranging it and supportin it in position to receive a pattern making material contact with the surface that had been in oontaot with last and casting suc material thereagainet form a pattern having a surface corresponding to said surfaoe of said integument and producin a male die from said The process in claim in which said integument is f rmed by immersing said shoe last in molten thermoplastic withdrawin setting said material on said The prooess in claim in whloh integument fibers are placed upon portions of said last prior to immersion thereof in said molten The prooes as defined by claim 4 in which said integument is made thicker at the feather edge o said last on said upper The process defined b claim 1 in which said diaphragm is a fluid bath in a closed chamber and said die and said bath heated independently of eac process as by claim 1 in which said shaped material is placed upon a shoe last to a The as by claim in desired components a shoe upper placed on upper material prior to pressing said die The as defined by in which the shape of pattern is before said die made therefrom by a flexible plastic material over said fixing the shape of paid removing it from pattern and wrapping it about the shoe last on which said integument was formed to determine its fit Agent insufficientOCRQuality