US2556364A - Flexible insole - Google Patents

Description

June l2, 1951 H. G. LUMBARD FLEXIBLE INsoLE Filed Feb. 12, 1949 Patented June 12, `1951 1' FLEXIBLE INSOLE Henry G. Lumbard, Auburn, Maine Application February-12, 1949, Serial No. 716,004

My invention relates to shoemaking and in particular to a shoe incorporating in its structure a `flexible insole of novel construction.

In one aspect my invention comprises an improvement upon the shoe disclosed in my prior Patent No. 2,211,509 granted August 13, 1940 and dealing with a flexible insole in which the forepart is provided with a number of rows of short through-and-through slashes extending transversely across the sole from edge to edge, the slashes in one row being staggered with respect to slashes in adjacent rows.

p For vreasons of economy it has become almost universal in shoemaking to employ artificial materials for insoles, leather being too expensive 1 I(Illaim. (Cl. 36-44) except in the more costly models. Wide use has been made of various kinds of fiber board, generally composed of paper pulp compounded with suitable sizings and binders and then calendered into sheet form. One practical difiiculty encountered in the use of such materials is the fact that an insole material sufficiently flexible for use in shoemaking is undesirably compressible. The result has been that after a moderate period of wear, the compression of the insole effectively enlarges thecavity provided for the foot, thus changing the fit of the shoe, while an'incompressible material produces a relatively inflexible and therefore unsaleable shoe.

My invention is based on the discovery that a dense incompressible brous material may successfully be employed for insoles provided it is slashed in the manner disclosed in my prior patent and further provided the correct relationship is maintained between the direction of the slashes and the direction of the grain of the material.

The most important object of my invention-is to improve the quality of a shoe with particular respect to exibility and adherence to the shape of the last.

Another object of the invention is to facilitate and improve the lasting operation involved in shoemaking.

Another object of my invention is to increase both the flexibility and Wear-resistant quality of shoes.

,An important feature of the invention resides in an insole having a forepart portion of relatively dense, incompressible fibrous material in which the grain runs parallel to the long axis ofthe sole and which is provided with a plurality of rows of short through-and-through slashes, the rows extending completely across the sole substantially perpendicular to the grain of the fibrous 2 material and so arranged that the slashes in one row are staggered with respect to slashes in adjacent rows.

These and other objects and features of the invention will more readily be understood and appreciated from the following detailed description of a preferred embodiment thereof selected for purposes of illustration and shown in the accompanying drawing ,in which:

Fig. 1 is a plan view of a composite sheet from which a plurality of sole pieces may be cut,

Fig. 2 is a plan view of an insole formed in accordance with the invention, and

Fig. 3 is a plan view on an enlarged scale illustrating the relation of the slashes to the grain of the material.

l-Iitherto fiber board and other artificial fibrous materials employed for the manufacture of insoles have been so prepared that in their finished form they are relatively spongy, compressible, and flexible. Consequently they tend to mat down and compress under the repeated pressure of the foot in the shoe, a condition which not only alters the volume of the foot cavity but also tends to promote the formation of wrinkles and irregularities in the surface of the insole resulting in the discomfort to the wearer.

Materials of the same genus but dense and incompressible are employed in the manufacture of articles other than shoes. These materials have hitherto been considered unsuitable for shoemaking because of their stiffness. The distinguishing characteristics of material of this kind are that it is dry calendered, that the calender pressure is much greater than that normally employed for the manufacture of insole material, and that the finished product is even denser than leather and, of course, a great deal denser than ordinary fiber boards used for insoles. I am not fully acquainted with the exact constituents of the fiber board here involved because the manufacturers regard them as secret and I have no means of discovering them. I do know, however, that the material comprises pulp fibers bound With latex and combined with fillers unknown to me. One material I have found eminently satisfactory is manufactured by the United States Rubber Company and termed a beater form latex fiber board.

It is material of this sort that I shall refer to herein as relatively dense incompressible fibrous material.

As with all materials of this kind, the fibers are oriented so that the majority of them are substantially parallel, to an extent sufficient to form incompressible material, the provision of slashes running parallel to the grain is not satisfactoy because the slashes cannot be expanded so that the sole will maintain a permanent expanded setf In fact, the slashes will tend to close up, the lips of the slashes rub against one another as the sole is flexed during wear, and this fact tends greatly to increase the formation of Wrinkles.

If, however, the relatively dense incompressible material is so arranged that the grain runs parallel to the long axis of the sole and the slashes then run across the grain, or perpendicular tov it, the sole is not only satisfactorily flexible and capable of expansion to a permanent set condition, but the rigidity and stiffness of the material provides a member much better adapted for lasting purposes. Moreover the material is so stiff that it is unnecessary to follow the normal process of cementing to the toe portion a ply of stii, reinforcing material adapted to render the toe capable of withstanding the stresses normally engendered vin the lasting operation. Since the stresses at the toe are largely transverse to the direction of the grain, the tendency of the toe to cork or buckle is eliminated. Finally, the material does not mat down or otherwise change its dimensions during wear; hence an originally satisfactory iit is maintained during the life of the shoe.

In Fig. l I have shown a composite sheet from which a number of insoles may be dyed out. The sheet comprises one band i9 of the relatively dense incompressible fibrous material suitable for the foreppart of the sole and cemented through a conventional skived joint to a band i2 of harder and stiffer material suitable for the heel and shank portions of the insole. The composite sheet is passed through a slashing machine which forms a number of parallel rows of short through-and-through slashes in the band IEE, the slashes in each row being staggered with respect to slashes in the adjacent rows. The slashes in each row are separated by relatively short unsevered portions of full thickness. In Fig. 3 the arrangement of the slashes lil is shown on an enlarged scale. The unsevered portions I6 arealso staggered in adjacent rows. Examination of Fig. 3 will also show that the direction or grain of the oriented fibers IS is at right angles to the long axis of the slashes, or parallel to the long axis of the sole.

It should be stated that the condition of the slashes shown in Fig. 3 illustrates the effect of the expansion or stretching operation preferably carried out before the sole members are kept from the composite sheet, although it is also possible to stretch and expand the individual soles. The nature of the material is such that when the stretching tension is released, the slashes do not close to their original condition but retreat to an intermediate, permanent set in which the slashes are at least partially opened, and the cut edges do not come in contact for most of their lengths.

In Fig. 2 I have shown in perspective an insole constructed in accordance with the invention and provided forwardly of the shank. with a covering ply 20 of thin, flexible textile material cemented in place. The purpose of the covering vply 2U is to prevent the deposition of cement in the slashes where*V the shoe-making process involves either cement lasting or cement sole attaching. The ply 20 is so thin and flexible that it does not appreciably detract from the flexibility 0f the insole. I have found in practice that a sole constructed in accordance with my invention affords a greatly improved lasting operation since the stiffness of the material successfully withstands lasting stresses which sometimes result in distortion of the sole member. Moreover the incompressibility of the material makes for a firm, sharp sole edge about which the lasting allowance of the upper is drawn. Consequently the lasted shoe is neater in appearance and more closely a replica of the configuration of the last and can be obtained when a relatively spongy insole member is utilized.

Having now described and illustra-ted a preferred embodiment of my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

A sole piece havingtoe and forepart portions of a relatively stiff, dense, incompressible ber board in which the grain runs substantially parallel to the longitudinal axis of the sole, the forepart portion being provided with a plurality 0f parallel rows of short through-and-through slashes, the slashes running from edge to edge of thel sole and substantially perpendicular to the grain of the ber board, the slashes in each row being staggered with respect to the slashes in adjacent rows and set 'with their opposite edges spaced out of contact with each other, and a thin flexible cover secured to one face of the sole piece and serving to prevent the deposition of cement in the open slashes.

HENRY Cf. LUMBARD.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 271,798 Cooley Feb. 6, 1883 1,192,794 Price July 25, 1916 1,671,914 Wescott May 29, 1928 1,702,225 Wescott Feb. 12, 19729 2,130,375 Atkins Sept. 20, 1938 2,211,509 Lumbard Aug. 13, 1940 2,309,673 Schlear Feb. 2, 1943 2,350,053 Lumbard May 30, 1944

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