Apparatus and method for producing toe caps for safety shoes

Abstract

An apparatus for producing toe caps for safety shoes and the like made of aluminum, aluminum alloys and light alloys in general, comprising a bottom die and a top die which can be associated with respective platens and can be mated so as to form at least one impression. The apparatus further comprises at least one male plug that can be inserted in the impression in order to form the shape of the part being formed and is suitable to act as a flow control element for the duct for introducing the liquid metal in the impression.

1 . An apparatus for producing toe caps for safety shoes and the like, made of aluminum, aluminum alloys and light alloys in general, comprising a bottom die ( 1 ) and a top die ( 2 ) which can be associated with respective platens ( 3 , 4 ) and can be mated so as to form at least one impression ( 5 ), characterized in that it comprises at least one male plug ( 20 ) that can be inserted in said impression ( 5 ) in order to form the shape of the part (P) being formed and is adapted to act as a flow control element for the duct ( 10 ) for introducing the liquid metal in said impression ( 5 ).  
     
     
         2 . The apparatus according to  claim 1 , characterized in that said liquid metal inflow duct ( 10 ) is formed at said bottom die ( 1 ).  
     
     
         3 . The apparatus according to the preceding claims, characterized in that said male plug ( 20 ) is supported by said top die ( 2 ) and is connected to means ( 21 ) for translational motion with respect to said top die ( 2 ).  
     
     
         4 . The apparatus according to one or more of the preceding claims, characterized in that said male plug ( 20 ) has a flattened portion ( 22 ) for closing the passage connecting said liquid metal inflow duct ( 10 ) and said impression ( 5 ).  
     
     
         5 . The apparatus according to one or more of the preceding claims, characterized in that said male plug ( 20 ) is adapted to apply a pressure between 500 and 1300 kg/cm 2  to the liquid metal that is present in said impression ( 5 ).  
     
     
         6 . The apparatus according to one or more of the preceding claims, characterized in that it comprises lower heating resistors ( 30 ) at said bottom die ( 1 ), upper heating resistors ( 31 ) at said top die ( 2 ), and male plug heating resistors.  
     
     
         7 . The apparatus according to one or more of the preceding claims, characterized in that the difference between the temperature of the liquid metal before casting and the temperature of said dies ( 1 , 2 ) is between 150 and 250° C., preferably 200° C.  
     
     
         8 . The apparatus according to one or more of the preceding claims, characterized in that it comprises an ejector ( 40 ), which is provided on the bottom of said impression ( 5 ) and connected to an ejector piston ( 41 ) for the release of the solidified part (P) from said impression ( 5 ).  
     
     
         9 . A method for producing toe caps for safety shoes and the like made of aluminum, aluminum alloys and light alloys in general, characterized in that it consists in introducing dosed liquid metal in an impression formed by a bottom die and a top die, in introducing in said impression a male plug adapted to apply a preset pressure to said metal and to prevent connection to the liquid metal inflow duct, in performing the solidification of the part under pressure for a preset time, in performing the ejection of the part with respect to the impression, and in removing the male plug from the part.  
     
     
         10 . The method according to  claim 9 , characterized in that the difference in temperature between the liquid metal and the dies that form said impression is between 150 and 250° C., preferably 200° C.  
     
     
         11 . The method according to one or more of the preceding claims, characterized in that said male plug applies a pressure between 500 and 1300 kg/cm 2  during the solidification of the part.  
     
     
         12 . A toe cap for safety shoes and the like, made with the apparatus of  claim 1  and according to the method of  claim 9 , characterized in that it comprises a body formed by casting liquid aluminum, aluminum alloys and light alloys in general, said body having a differentiated thickness in its various points and being sprueless.