Patent Publication Number: US-4320588-A

Title: Insole, in particular for ladies&#39; shoes

Description:
The present invention concerns a shoe bottom for shoes, in particular for ladies&#39; shoes. The said shoe bottom is constructed to meet satisfactorily, with special reference to the physiological viewpoint, the user&#39;s requirements, in order to produce lightweight and resistant shoes, fulfilling also to the aesthetic requirements. 
     Another purpose of the present invention is to provide of a shoe bottom which can be fitted, as required, with a heel and/or a sole-the said sole being fitted on to the front part of the shoe bottom-showing the desired features, without being prejudicial to the stoutness and flexibility of the above mentioned shoe bottom. 
     Still another purpose of the invention is to provide a lightweight and flexible shoe bottom capable of resisting the stresses of use and which can be equipped with a heel, even of a high heel, without impairing the structure thereof, during walking. 
     The shoe bottom according to the invention is characterized by a grooved upper surface, to house and retain the footsole and the lower surface of said shoe bottom retains, at the rear part thereof, the heel of the shoe, while the middle area is transversally curved and connected with the front part by means of arches of a circle of a progressively increasing width and with incremented radius of curvature, to form, at the front end, a substantially flat area or transversally flexible sale in correspondence with the articulations of the toes. The heel for the shoe can be either inserted or embodied in the shoe bottom. 
     The annexed drawing shows, by way of example, an advantageous form of embodiment of the above described shoe bottom according to the invention, advantageously made of a pressed plastic material, preferably of the thermoplastic type. 
    
    
     In the said drawing: 
     FIG. 1 is a side elevation of the shoe bottom; 
     FIG. 2 is a longitudinal cross-section; 
     FIGS. 3 to 6 are sections, on an enlarged scale and, respectively, on the lines from III--III to VI--VI of FIG. 1. 
    
    
     With reference to the figures of the drawing, the illustrated shoe bottom consists of a body of a pressed thermoplastic material, which is advantageously shaped, in such a way as to form, in relation to the upper surface A thereof, a rear cavity A1 which houses the heel of the foot and which connects, at the front side, with a middle length A2, downwardly inclined and appropriately curved transversally, to house and to retain the hollow of the foot. The surface related to the middle length A2 extends then in the direction of the front part of the shoe bottom with a curved length A3, to terminate with an ample area A4 for the sole of the foot. This area is slightly hollow and terminates with a point A5 which is slightly upturned, in order to house and to retain the toes of the foot. 
     The lower face B of the shoe bottom is shaped accordin: toward the rear part thereof it retains the heel C for the shoe, which can form a single body with the shoe bottom or otherwise be inserted into it and fixed there, for instance by means of screws. In the last mentioned case the shoe bottom can show a flat area B1 to retain the heel of a shoe of any appropriate type. 
     The middle part of the lower face B of the shoe shows a profile B2 which is substantially identical with that (A2) of the upper surface: but the transverse curve of the said profile is such as to form a beam, the thickness of which decreases rapidly in the direction of the front part, while its length increases toward the sole. In other words, the transverse bending radius of curvature of area B2 is less than the corresponding transverse radius of the grooving A2 and the said radius increases gradually during its approach to the sole. In such a way, as well as in relation to the variation of the radius concerned, and to the width thereof, a shaped beam B3 is realized in relation to the middle part of the shoe bottom, the thickness of which decreases from the rear to the front part of the shoe bottom, to provide, within the area of sole B4, particularly in the part corresponding to the articulation of the toes, according to sectional line VI--VI, an advantageously reduced thickness having maximum flexibility, to allow for an easy and quick walk of the wearer. The front area B4 of the shoe bottom can be provided with a cavity B6 of appropriate depth and delimited, at least partly, by an edge B5 of an appropriate width; the said cavity is designed to house and retain an element having a good resistance to wear, for example of leather and fixed there by means of an adhesive or another appropriate way, since the aforementioned element of long wear is retained by the walls of edges B5. If desired and in particular when edge B5 extends to the sole, said edge can be provided with longitudinal rifles or the like, to facilitate the execution of seams or the like designed to grip and retain the element of long wear, the uppers or other parts of the shoe. 
     Due to the structure of the shoe bottom, even if it comprises areas of resistance to wear it maintains its flexibility of the sole almost unaltered. Furthermore the said shoe bottom, object of the present invention presents, as previously mentioned, a remarkable resistance, owing to its beam-like structure localized in the middle part thereof. 
     As above mentioned, the shoe bottom object of the invention is formed, at least in part, of a plastic material, for instance of the thermoplastic type such as polyamides, co-polymers and other similar products.