Abstract:
A protective sole plate for protective footwear having a number of sole plate bodies, optionally of an electrically and thermally insulating material, joined together with transverse hinged joint(s) whereby each sole plate body can rotate about the transverse hinge relative to other sole plate bodies thereby enabling flexing of the sole plate while maintaining puncture resistance.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to an inner sole for protective shoes, which is made of rigid plastic bodies hinged together to provide flexing, is penetration resistant, thermally insulating and electrically insulating.  
       BACKGROUND OF THE ART  
       [0002]     Protective shoes provide foot protection for those who work in a high risk environment. Protective shoes normally have penetration resistance in the sole and crushing resistance in the toe and metatarsal area.  
         [0003]     Regarding the configuration of prior art protective penetration resistant soles, conventionally a metal inner sole plate is sandwiched between two layers  61  of fabric material and is bonded to the shoe sole. A protective metal shoe head is positioned on the shoe sole about the toe area. The metal inner sole plate prevents sharp tips from penetrating and the rigid protective shoe head protects the toes from injury from falling objects, or impact.  
         [0004]     However, prior art protective soles have shortcomings in use. Conventional metal sole plates are often uncomfortable since it is difficult to fabricate metal in a pressing process with a smooth concave top surface to match the contours of a wearer&#39;s foot. The metal sole plate must have an adequate thickness to achieve penetration resistance, which complicates fabrication into a curved shape, reduces flexibility and thus diminishes the comfort of the shoe.  
         [0005]     The conventional metal sole plate and metal protective shoe head cannot provide effective electric shock resistance and thermal insulation. Therefore, conventional protective shoes are not well adapted for use in an environment where electric shock is a risk or where thermal resistance to heat and cold are required.  
         [0006]     The shape of a conventional metal sole plate is substantially flat and does not include a concave upper surface to follow the shape of the wearer&#39;s foot sole. Aside from the comfort factor, the flat shape results in protective coverage narrower than the wearer&#39;s foot sole and thus reduces the protection from sideways penetration prevention around the edges of the foot.  
         [0007]     Conventional protective soles cannot provide an effective overall heat or cold resistance because the protective sole plate and protective shoe head are of metal, which is a good thermal conductor and consequently is also a poor thermal insulator. Protective shoes are worn outdoors in construction or military environments and worn indoors in various industrial premises where the comfort of the wearer while exposed to heat and cold environments are a concern.  
       DISCLOSURE OF THE INVENTION  
       [0008]     The invention provides a protective sole plate for protective footwear having a plurality of sole plate bodies, optionally of an electrically and thermally insulating material, joined together with at least one transverse hinged joint whereby each sole plate body can rotate about the transverse hinge relative to other sole plate bodies, each body including at least one transverse edge adapted for hinged interaction with an adjacent transverse edge of an adjacent sole plate body.  
         [0009]     Objects of the invention will be apparent from review of the disclosure, drawings and description of the invention below. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is an exploded perspective view of a rigid hinged inner sole plate according to one embodiment of the present invention;  
         [0011]      FIG. 2  is a longitudinal cross-sectional view of a protective shoe with the sole plate of  FIG. 1  installed together with a protective toe cap;  
         [0012]      FIG. 3  is a top plan view of the rigid sole plate of  FIG. 1 ;  
         [0013]      FIG. 4  is a bottom plan view of the rigid sole plate;  
         [0014]      FIG. 5  is a cross-sectional view, taken along line  5 - 5  of  FIG. 3 ;  
         [0015]      FIG. 6  is a cross-sectional view, taken along line  6 - 6  of  FIG. 3 ;  
         [0016]      FIG. 7  is a detail sectional view, of the hinged joint in  FIG. 5 ;  
         [0017]      FIG. 8  is a sectional view through a protective show with the sole plate of the present invention under a bending condition in use;  
         [0018]      FIG. 9  is a schematic cross-sectional view of the prior art one-piece protective sole; and  
         [0019]      FIG. 10  is a schematic exploded perspective view of a prior art protective shoe. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0020]     Referring to  FIGS. 9 and 10 , which illustrate a configuration of the conventional shoes, a shoe sole  60  is topped with a conventional metal inner sole plate  70 , which is bonded together therewith. The metal inner sole plate  70  itself is sandwiched between two layers  61  of material, in order to obtain a better combination. A protective shoe head  71 , which is made of metal material, is positioned on the shoe sole  60  at a location corresponding to the wearer&#39;s toes.  
         [0021]     Thus, the wearer&#39;s foot sole is protected by the inner sole plate  70 . The metal inner sole plate  70  prevents sharp tips of an object from penetrating therethrough to injure the wearer&#39;s foot sole when the wearer&#39;s foot accidentally steps on the sharp tips of the object. The rigid protective shoe head  71  protects the vulnerable toes from being injured even when a heavy object falls thereon.  
         [0022]     Referring to  FIGS. 1-7 , the present invention relates to an improvement of an inner sole configuration for protective shoes in which a rigid plastic inner sole plate  1  is bonded to a rubber shoe sole  50 . A layer  51  of a material is bonded to each of the top and bottom surfaces of the rigid plastic inner sole plate  1 . A protective shoe head  40  (as shown in  FIG. 2 ) is affixed to the shoe sole  50  in a position covering the wearer&#39;s toes.  
         [0023]     In this configuration the rigid plastic inner sole plate  1  and the shoe head  40  are made of thermosetting resin with reinforcing fibers. The shoe head  40  however can also be of metal. The rigid plastic inner sole plate  1  is configured with first, second and third plate bodies  10 ,  20  and  30  positioned in a longitudinal sequence in correspondence with the positions of bendable portions of the wearer&#39;s foot sole where the foot joints are located. The plate  1  includes a top surface with a concavity  100  (as shown in  FIG. 6 ) according to bioengineering, thereby being adapted for supporting the wearer&#39;s foot sole. The plate  1  includes a bottom surface having a curved configuration  101  at the periphery thereof.  
         [0024]     The first plate body  10  includes a transverse edge  11  at an end thereof adjacent to second plate body  20  and forming a transverse hinged joint therewith. The transverse edge  11  has at an upper part thereof a recess  110  extending laterally therethrough and defines at a lower part thereof a rounded extending flange  111  (as best shown in  FIG. 5 ).  
         [0025]     The second plate body  20  includes a transverse edge  21  at a first end thereof adjacent to the first plate body  10 . The transverse edge  21  has an extending flange  210  extending from an upper part thereof. The flange  210  is enabled to rest in the recess  110  of the first plate body  10 . A clearance is formed between an end of the recess  110  of the first plate body  10  and an end of flange  210 . The transverse edge  21  further includes a laterally extending rounded flange  211  (as shown in  FIG. 5 ). The second plate body  20  includes a transverse edge  22  at a second end thereof opposite to the first end thereof. The transverse edge  22  includes a recess  220  formed at an upper part and extending laterally therethrough, and a laterally extending rounded flange  221  (as shown in  FIGS. 1 and 5 ). An appropriate clearance is formed at each of the opposite side margins of the hinged plate  1  between a lower part of the connecting portion  11  of the first plate body  10  and a lower part of the connecting portion  21  of the second plate body  20 . The transverse edges  11  and  21  contact each other at a middle part thereof between the opposite side margins.  
         [0026]     The third plate body  30  includes a transverse edge  31  at first end thereof toward the second plate body  20 . The transverse edge  31  has a flange  310  extending from an upper part thereof to rest in the recess  220  of the second plate body  20 . A clearance is formed between an end of the recess  220  of the second plate body  20  and an end of the flange  310 . An appropriate clearance is formed at each of opposite side margins of the plate  1  between a lower part of the transverse edge  22  of the second plate body  20  and a lower part of the transverse edge  31  of the third plate body  30 . The transverse edges  22  and  31  contact each other at a middle part between the opposite side margins. Furthermore, the transverse edge  31  includes a laterally extending rounded bottom end surface  311  (as shown in  FIG. 5  and  7 ). Thus, the first and second plate bodies  10 ,  20  are enabled to bend freely and rotate relative to each other about a transverse hinge.  
         [0027]     The third plate body  30  further includes a recess  32  formed in a lower part of a second end thereof opposite to the first end thereof for engaging a rim of a rigid plastic shoe head.  
         [0028]     In such a configuration according to the present invention, the rigid plastic inner sole plate  1  benefits from the rigidity and solidity of the insulating plastic material, provides an optimal overall result of electric shock resistance, heat resistance and thermal insulation, and thereby improves the insulation safety of the protective shoes. Additionally, the rigid plastic inner sole plate  1  provides the protection of the wearer&#39;s foot sole from injury resulting from sharp tips of an object penetrating the rubber shoe sole  50  of the protective shoes.  
         [0029]     The rigid plastic inner sole plate  1  of the present invention has a concave top surface  100  which is better fitted to the wearer&#39;s foot soles, thereby providing a better coverage and support for the wearer&#39;s foot soles, and thus improving the comfort of the protective shoes. Also because of the concave top surface  100 , the rigid plastic inner sole plate  1  extends to wrap around the opposite side areas of the wearer&#39;s foot soles, forming a larger coverage for the wearer&#39;s foot soles. When a sharp tip of an object penetrates the shoe sole of the protective shoe at the side margins thereof, and then contacts the convex bottom surface  101  at the periphery of the plate  1 , the sharp tip will be forced and guided to project laterally and outwardly, thereby being prevented from injuring the wearer&#39;s foot sole. Therefore, the safety of the protective shoes regarding lateral penetration prevention is significantly improved.  
         [0030]     Furthermore, in accordance with the bendable areas of the wearer&#39;s foot sole at the joints thereof, the rigid plastic inner sole plate  1  of the present invention includes the first, second and third plate bodies  10 ,  20  and  30  which connect to one another at transverse hinged joints, and the plate  1  defines an appropriate clearance respectively between the transverse edges  11 ,  21  of the respective first and second plate bodies  10  and  20 , between the transverse edges  22 ,  31  of the respective second and third plate bodies  20  and  30 . Thus, the first, second and third plate bodies  10 ,  20  and  30  are freely bendable such that the respective plate bodies  10 ,  20  and  30  are hinged to bend corresponding to various bending directions of the wearer&#39;s foot sole joints (as shown in  FIG. 8 ). The wearer&#39;s foot movement will not thus be restricted by the protective shoe, and the wearer will thus feel much more comfortable.  
         [0031]     Conclusively, in contrast to the soles of the conventional protective shoes, the improvement of the rigid plastic inner sole configuration of the present invention results in much better safety and comfort of the protective shoes when in use.