Dual-density EVA footwear mid-sole and method for making same

Abstract

The method for fabricating a dual-density mid-sole includes the steps of: injection molding EVA material of a first density into a block; placing the first density EVA block and raw EVA material pellets of a second density together in a mold cavity; and applying heat and pressure to the first density EVA block and raw EVA material pellets of a second density in the mold cavity to form a fused component. The fused component is shaped and detailed into the mid-sole in a separate mold cavity. The result is a dual-density mid-sole consisting of one or more blocks of EVA material of a first density fused to EVA material of a second density where the size, shape and location of the different density sections can be accurately controlled and precisely defined. An article of footwear including an upper, the dual-density mid-sole consisting of one or more blocks of EVA material of a first density fused to EVA material of a second density, and an outsole, may be formed.

1 . A method for fabricating a dual-density mid-sole comprising the steps of:
 forming EVA material of a first density into a block;   placing the first density EVA block and raw EVA material of a second density together; and   applying heat and pressure to the first density EVA block and raw EVA material of a second density to form a fused component.   
     
     
         2 . The method of  claim 1  wherein the raw EVA material of a second density is in the form of pellets when placed together with the first density EVA block. 
     
     
         3 . The method of  claim 1  wherein the step of forming a block comprises injection molding EVA material of a first density into a block. 
     
     
         4 . The method of  claim 1  further comprising the step of trimming the block. 
     
     
         5 . The method of  claim 1  further comprising the step of shaping the fused component into the mid-sole. 
     
     
         6 . The method of  claim 1  further comprising the step of creating design details on the exterior surface of the fused component. 
     
     
         7 . The method of  claim 6  further comprising the step of shaping the fused component into the mid-sole. 
     
     
         8 . The method of  claim 7  wherein the step of shaping and the step of detailing are combined into a single step. 
     
     
         9 . The method of  claim 7  wherein the step of shaping and the step of detailing comprise the steps of placing the fused component in a mold cavity and applying heat and pressure to the fused component. 
     
     
         10 . The method of  claim 1  wherein the first density EVA material has a lower density than the second density EVA material. 
     
     
         11 . The method of  claim 1  wherein the raw EVA material of a second density has a higher density than the first density EVA material. 
     
     
         12 . The method of  claim 1  further comprising the step of measuring the amount of EVA material of a second density placed together with the first density EVA block. 
     
     
         13 . The method of  claim 12  wherein the step of measuring comprises the step of measuring the amount of raw EVA material of a second density placed in the mold cavity with the bock as a function of the volume of the block. 
     
     
         14 . The method of  claim 1  wherein the step of placing the first density EVA block and the raw EVA material of a second density together comprises the step of placing the first density EVA block in a mold cavity and pouring the raw EVA material of a second density into the mold cavity. 
     
     
         15 . The method of  claim 14  wherein the step of applying heat and pressure to the block and raw material comprises the step of applying heat and pressure to the block and raw material in the mold cavity. 
     
     
         16 . The method of  claim 1  further comprising the step of introducing a second first density block prior to applying heat and pressure to fuse the component. 
     
     
         17 . A method for fabricating a dual-density mid-sole comprising the steps of:
 injection molding EVA material of a first density into a block;   placing the first density EVA block and raw EVA material pellets of a second density together in a cavity; and   applying heat and pressure to the first density EVA block and raw EVA material pellets of a second density in the cavity to form a fused component.   
     
     
         18 . The method of  claim 17  further comprising the step of shaping the fused component into the mid-sole. 
     
     
         19 . A dual-density mid-sole comprising a block of EVA material of a first density fused to EVA material of a second density. 
     
     
         20 . The mid-sole of  claim 19  wherein the EVA block is formed separately, before the EVA block and EVA material are fused together. 
     
     
         21 . A dual-density mid-sole comprising first and second blocks of EVA material of a first density fused to EVA material of a second density. 
     
     
         22 . The mid-sole of  claim 21  wherein the blocks are formed by injection molding, before the EVA material and blocks are fused together. 
     
     
         23 . An article of footwear comprising an upper, a dual-density mid-sole comprising a block of EVA material of a first density fused to EVA material of a second density, and an outsole.