Abstract:
A resilient shoe sole having a less resilient outer layer and a more resilient inner layer, and retractable studs anchored in the inner, more resilient layer. The bottom surface of the sole has annular grooves formed around the tip portions of the studs to permit those portions to flex when pressure is applied to the bottom surface, as during walking on a hard surface.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to improvements in resilient, all-surface soles that are applied to or or are integral part of footwear. More specifically, it relates to improvements in such soles as described, illustrated and claimed in my U.S. Pat. No. 5,634,283, which was issued on Jun. 3, 1997.  
         BACKGROUND OF THE INVENTION  
         [0002]    As more fully disclosed in U.S. Pat. No. 5,634,283, on which I am the named inventor and the disclosure of which is hereby fully incorporated herein by referende, it has long been a challenge to those of skill in the art of designing footwear to devise footwear having soles that enable the wearer to have traction on surfaces that may be classified as slippery, e.g., ice or wet sod. With regard to the lastter surfaces, golf shoes are a common expedient. Gold shoe normally have soles with metal spikes or studs that extend at right angles to the bottom surface of the sole, so that when the golf shoes are worn on sod, the spikes readily penetrate the sod to a depth such that, when the golfer exerts downward pressure on the shoe sole, the footwear remains in a fixed position relative to the sod despite substantial torque that is applied by the golfer during his swing.  
           [0003]    It will be apparent, however, that while shoes having soles with spikes extending outwardly from them are quite useful when one is walking on sod, or even a surface such as ice or compacted snow, when one then stands on a hard, smooth surface into which the spikes can make no substantial penetration, such spiked footwear can be a hazard to the wearer as well as the hard surface, which can be defaced and scratched by the shoe spikes.  
           [0004]    In order to address this problem my prior patent disclosed and claimed a footwear sole formed from a resilient material such as rubber and having a plurality of metal studs mounted in the sole, each stud or spike having an anchoring poortion embedded in the resilient sole, a tip portion extending outwardly from the sole surface, and a shaft portion joining the tip and the anchor of the stud. When the footwear is worn, the studs are retracted inwardly from the surface of the sole so that on a hard surface, the tip portions of the studs will be located at the relatively hard surface and will not penetrate it. However, when the wearer is standing on a relatively soft surface, such as sod or wet ice, the studs will extend outwardly from the sole a distance sufficient to enable the wearer to obtain purchase on that softer surface due to penetration of the studs into the surface.  
           [0005]    While that invention is broadly utilitarian, i6 does not address problems that may arise in specific situations. Thus, where a woman&#39;s shoe is to be made with such a sole, it is apparent that pressure on the resilient sole will be less than that exerted by a shoe where the wearer is a 300-lb. man. Moreover, if the sole is formed from rubber or other material of a high degree of resilience such tht when the shoe is worn by a lightweight person the studs will nevertheless retract to the bottom surface of the sole, the sole formed from such soft rubber may not present a firm support to the wearer. In addition, even when there is an optimum balance between the resilience of the sole and the weight of the wearer, there still may be some scarification of a hard surface when the wearer i of the shoes slides his or her feet across that surface.  
           [0006]    It is, therefore, one object of the present invention to provide a studded sole for footwear in which the resilience of the sole at its bottom, work-contacting surface is not necessarily determinative of the resistance of the sole to retraction of the studs while the footwear is being worn.  
           [0007]    Expressed otherwise, it is an object of my invention to overcome the problem of adapting a studded, resilient sole to varying surface and weights of the wearer so that the studs will readily engage surfaces on which they are designed to penetrate, but nevertheless enable the wearer to utilize the shoes or other footwear on a hard surface, such as a tile floor, without unduly marring that surface.  
         SUMMARY OF THE INVENTION  
         [0008]    In one broad aspect of my invention, it comprises utilizing studs that have an anchoring portion interior of the sole and adapting that portion of the sole that engages the anchoring portion of the stud to the specific conditions toward which the stud is designed. This requires that the sole not have a uniform resilience or density, because it is not formed from rubber or other material that is uniformly resilient. Thus, the resilience of the rubber will vary through the depth of the sole as that depth is measured from the bottom, work-contacting surface of the sole to that sole surface that contacts the upper of the footwear.  
           [0009]    In one specific embodiment the sole is formed so that the resilience thereof varies between the bottom and upper surfaces of the sole. Such variation can be uniform, that is, more resilient at the bottom, work-contacting surface of the sole and least resilient at the portion of the sole that contact the shoe upper. In another embodiment the sole is formed from layers of rubber, a more resilient zone being located at the bottom of the sole even at the uppermost zone, with a less resilient, i.e., harder zone being formed at a central location to lend stability to the shoe. Yet in another embodiment the more resilient zone can be located between the two, harder zones of rubber. It is in this softer zone of rubber that the anchoring portion of a stud is located; in this manner an easily retractable stud is formed although the work contacting surface of the sole is relatively hard, so that the sole may be worn on a hard, indoor surface without unduly scuffing it.  
           [0010]    In order to provide for the same, general purpose, another embodiment of my invention is based on the formation of a groove in the bottom, work contacting surface of the sole. Such groove is annular in shape and surrounds the tip of a stud that projects from the bottom surface. As the stud has a degree of resilience, itself, the groove permits the stud to flex to the side when excess pressure is directed against it, rather than have the additional pressure on the study force the stud into a hard underlying surface which it will then tend to scar.  
           [0011]    With respect to processes for the manufacture of soles that have varying degrees of resilience through their depths, the soles can be formed in a single molding operation in which the resilient material, such as natural or synthetic rubber, has its composition varied from one surface of the sheet from which the soles are formed to the other surface. Alternatively, the sole can be molded from individual sheets. For example, two sheets of less resilient and one sheet or more resilient can be formed and cut to size, and the more resilient layer sandwiched between the harder layers and molded to them. Production efficiencies may determine which methods of forming the desired structures prove more effective.  
           [0012]    These and other objects, features and advantages of the present invention will become more apparent when considered in connection with preferred embodiments of my invention as described in the specification hereinafter and as illustrated in the accompanying drawings, in which:  
           [0013]    [0013]FIG. 1 is a perspective view generally showing the exterior of footwear having an all-surface sole according to my invention;  
           [0014]    [0014]FIG. 2 is an enlarged sectional view illustrating the sole construction according to one preferred embodiment of my invention;  
           [0015]    [0015]FIG. 3 is an enlarge sectional view illustrating another preferred embodiment of a sole construction according to my invention;  
           [0016]    [0016]FIG. 4 is an enlarged sectional view of a third, preferred embodiment;  
           [0017]    [0017]FIG. 5 is another section illustrating a variant of the embodiment of FIG. 4, and  
           [0018]    [0018]FIG. 6 is still another sectional view showing a variation that comprises a combination of previously illustrated preferred embodiments. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0019]    Referring now to the drawings, and in particular to FIG. 1 thereof, what is shown in an all-surface sold  10  in place on footwear  11 . Sole  10  may be permanently attached to shoe  11  or may be removable therefrom and placed, either with another, similar sole after excessive wear, or with another sole that has different characteristics.  
         [0020]    As generally shown, sole  10  has a bottom, work-contacting surface  12 , from which protrude a plurality of metal studs  13 . The upper surface  14  of the sole is not seen in FIG. 1, but lies in juxtaposition to the upper of the shoe  11 . The pattern in which the studs  13  are arranged is predetermined and is not considered to be part of the present invention.  
         [0021]    The structure of a stud  13 , which is preferably made of metal, is best seen in FIGS. 2 and 3. As is the case with the studs of my U.S. Pat. No. 5,634,283, each stud  13  is formed with an anchoring portion  15 , a tip portio  16 , and a cylindrical or conical shank or shaft portion  17  so that it will remain substantially in place in relation to the resilient material of the sole in which it is encased. The tip  16  may be of a variety of shapes so long as its function of engaging a surface on which the wearer of the footwear  11  places it is maintained. Thus, the tip portion  16  is shown as cylindrical, but may also be conical with the apex of the cone projecting outwardly from the bottom surface  12  of the sole  10 . The shaft  17  serves the function of connecting the tip and anchor of a stud. Indeed, the tip portion may simply be constituted as the extremity of the shaft  18 .  
         [0022]    What is important to certain embodiments of my resilient, all-surface sole is the nature of the composition of the sole  10 . In my patent it is disclosed, but not limited to being uniform and made from a resilient material, e.g., natural or synthetic rubber. In the embodiment of FIG. 2 the material from which the sole is formed is of the same general, resilient nature, but the sole is not uniform in substance or resiliency. The rubber body of the sole is harder, that is, of less resilience, at a location adjoining the bottom, work contacting surface  12  of the sole  10 . More dense, less resilient zones of the sole are indicated by reference number  20  and adjoin bottom surface  12 . Less dense portions are indicated by reference number  21  and adjoin upper sole surface  14 . Portions of intermediate density lie between the zones  20  and  21 , and are indicated by reference numeral  22 . As a consequence, in that illustrated embodiment the density of the sole  10  decreases from the sole bottom surface  12  to the sole upper surface  14 , and in this embodiment it is preferred that such decrease be uniform in its extent, that is, that the resilience of the sole uniformly increases as one moves from the bottom surface  12  to the upper surface  14  of the sole  10 .  
         [0023]    In the FIG. 2 embodiment it will also been seen that the anchoring portion  15  of the stud  13  is embedded in the rubber sole approximately halfway between the bottom and top sole surfaces. In this position the anchor  15  is located at a part of the thickness of the sole that is of lesser density and greater resilience than that portion  20  adjoining bottom surface  12 . In this structure the stud  13  will be able to be retracted more easily when the user of the footwear  22  steps on a hard surface than if the resilience of the sole were uniform throughout its depth. Yet the hardness of the rubber at the bottom surface of the sole will still be of greater density, and therefore provide greater wear resistance and sturdiness to the footwear. However, retraction of the stud will still be adequate if the wearer of the shoe is of light weight, for example.  
         [0024]    The illustration of FIG. 3 shows a different, preferred embodiment. Here harder rubber layers are disposed adjoining both surfaces of the sole  10 . Thus, a relatively hard layer  25  is located at the bottom surface  12  of the sole and, similarly, hard layer  27  is located at the upper surface  14  of the sole. However, those relatively hard layers have between them a softer, more resilient layer or zone  26 , which in effect is sandwiched between the more dense layers.  
         [0025]    The reason for the layering of more and less resilient zones in the FIG. 3 embodiment is to enable the stud  13  to be retracted more easily into the sole  10 , while still maintaining a relatively firm sole bottom surface that will resist undue wear. Thus, in this embodiment of my invention the shaft  17  of stud  13  extends through the less resilient portion  26  and into the more resilient portion  27 , in which the anchor  15  of stud  13  is located. While in FIG. 3 the anchor is illustrated as embedded in the more resilient layer  26 , it can also be positioned at the juncture of less resilient layer  25  and more resilient layer  26 . In this manner the stud is more readily retractable because its anchor portion  15  is encased within and/or cushioned by the more resilient zone  26 . Still, the less resilient outer layer  25  adjoining the bottom surface  12  of the sole  10  is in contact with the work, i.e., the surface on which the wearer is striding. In this manner ease of retractability of the stud or spike is enhanced while the wear resistance of the footwear is the same as if the denser bottom layer of the sole extended throughout the entirety of the sole.  
         [0026]    Still another embodiment of my invention is illustrated in FIG. 4 of the drawings. Here the sole  30  is formed of a single zone of rubber, and a cleat portion  31  extends downwardly and forms, in part, the bottom surface of the sole. Encased within the body of the sole is a stud  32 , comprised of an anchor  33  and a tip  34  joined by a shaft  35  that extends substantially perpendicular to the horizontal axis of the sole  30 . What is believed to be unique vis-α-vis my prior patent, however, is the groove  37  that surrounds the tip and forms an annular opening about the tip  34  and in this case a lower portion of the shaft  35 . As the shaft of the stud  32  is usually formed from metal, providing such an annular recess  37  enables some flexing of the stud when it contacts a hard surface, and such flexing prevents unwanted scarification of that surface in addition to the resilience imparted by the stud anchor  33  embedded in the resilient sole  30 .  
         [0027]    [0027]FIG. 5 shows another preferring embodiment of my invention that is similar to that of FIG. 4. The difference here is that the sole  40  is formed from two layers of rubber, an upper or inner layer  41  and an outer, work contacting zone or layer  42 . A stud  43  is provided, which stud includes an anchor  44  joined by a shaft  45  to a stud tip  46 . Here, too, the tip  46  is surrounded by annular recess  47  to permit some flexing of the tip and associated shank  45 . In the FIG. 5 embodiment outer layer or zone  42  is of harder, more wear resistance material, while inner layer  41  is more resilient. So, as the anchoring portion  44  of stud  43  is backed by more resilient zone  41 , the stud can be retracted far more easily than if it had to press against the harder, less resilient zone  42 .  
         [0028]    Finally, the embodiment illustrated in FIG. 6 employs another combination of hard or more resilient layers of rubber. In this embodiment sole  50  is formed from a relatively hard upper layer  51  of rubber or other material, to which is adhered a relatively resilient layer  52 . Then a cleat  53  formed of relatively hard rubber protrudes downwardly from the resilient layer  52 . The stud  54  extends with its tip  55  in hard layer  53  and shaft  56  passing through that hard layer into zone  52  in which its anchor  58  is encompassed. In this structure the stud  54  can be retracted with a fair degree of ease, as its anchor need only compress a part of the more resilient layer  52  while both the work contacting cleat  53  and the upper layer  51  of the sole  50  are formed from a less resilient material adapted to provide great wear resistance and rigidity to the sole in its entirety. In this embodiment as well, the annular recess  57  permits some flexibility of the tip and tip  55  and shaft  56  of the stud  54 .  
         [0029]    With regard to the manufacture of the soles disclosed herein, they can be made by molding in one piece or, where the sole is formed from layers of materials of difference degrees of resilience, by separately forming each layer and then fusing the layers together. The hardness of the synthetic or natural rubber compounds utilized will vary as set forth in U.S. Pat. No. 5,634,283, from between about 65 to 90 Durometer Shor A. Where greater hardness and less resilience are desired, the sole hardness will be at a maximum, whereas where much more resilience is desired, the Shor Durometer hardness will be at a minimum. Nevertheless, such variation in hardness are doubtless within the skill of those in this art, and I do not wish to be limited as to any specific hardness or resilience employed, other than as such hardness or resilience in one part of the sole may be contrasted with those factors in another layer of the sole.  
         [0030]    It will be apparent to those of skill in this art that certain modifications and alterations to the preferred embodiments of my invention described and illustrated herein will be found obvious without departing from the spirit of the invention. Exemplarily, the provision or deletion of a cleat from the bottom surface of the sole is an obvious expedient. It is desired, therefore, that all such alterations and modifications be included within the purview of the invention, which is to be limited only by the scope, including equivalents, of the following, appended claims.