Mold and process for manufacturing toothed sprockets for locking winding rollers of safety belts

Abstract

A mold for manufacturing toothed sprockets for locking winding rollers of safety belts, comprising a main cavity ( 4 ) to be filled with a molten metal alloy so as to define at least one disc-shaped body ( 102 ) of a toothed sprocket ( 100 ) having a toothing ( 101 ) on a peripheral surface thereof, and a secondary cavity ( 6 ) designed to define a tailpiece ( 105 ) jutting out of the toothed disc-shaped body ( 102 ) and brought into fluid communication with the main cavity ( 4 ). The main cavity ( 4 ) comprises a deflecting element ( 7 ) extending within the cavity ( 4 ) itself for deviating the metal alloy towards the secondary cavity ( 6 ).

1 . A mold for manufacturing toothed sprockets for locking winding rollers of safety belts, comprising:
 a main cavity to be filled with a molten metal alloy so as to define at least one toothed disc-shaped element having a toothing on a peripheral surface thereof; and   at least one secondary cavity brought into fluid communication with said main cavity, so as to define a tailpiece jutting out of the disc-shaped body;   characterized in that it comprises at least one deflecting element extending inside the main cavity for deviating the metal alloy towards said secondary cavity.   
   
   
       2 . The mold as claimed in  claim 1 , wherein said secondary cavity has a longitudinal extension direction oriented transversely of a diametrical extension plane of the main cavity defining said toothed disc-shaped body. 
   
   
       3 . The mold as claimed in  claim 1 , comprising an injection runner for the molten metal alloy, brought into fluid communication with said main cavity; said injection runner extending in a radial direction relative to said main cavity. 
   
   
       4 . The mold as claimed in  claim 1 , comprising a first and a second half having respective mutually facing surfaces designed to define said main cavity, and carrying said deflecting element and secondary cavity, respectively. 
   
   
       5 . The mold as claimed in  claim 1 , wherein the deflecting element is disposed in alignment relationship with a longitudinal extension direction of the secondary cavity. 
   
   
       6 . The mold as claimed in  claim 3 , wherein the deflecting element is disposed along the extension direction of the injection runner, in front of a gate of the injection runner for entering the main cavity. 
   
   
       7 . The mold as claimed in  claim 1 , wherein said deflecting element comprises an oblique surface for deviating the molten metal alloy towards said secondary cavity. 
   
   
       8 . Use of a mold as claimed in  claim 1 , for manufacturing toothed sprockets for safety belt locking systems in vehicles. 
   
   
       9 . A process for manufacturing a toothed sprocket for locking winding rollers of safety belts, comprising the steps of:
 providing a mold having a main cavity defining at least one toothed disc-shaped body and at least one secondary cavity brought into fluid communication with the main cavity so as to define a tailpiece jutting out of said toothed disc-shaped body;   pressure die-casting a molten metal alloy in said main cavity along a filling path thereof;   wherein during the die-casting step at least part of the molten metal alloy meets at least one deflecting element provided along the filling path for deviating said alloy towards said secondary cavity.   
   
   
       10 . The process as claimed in  claim 9 , wherein the secondary cavity has a longitudinal extension direction oriented transversely of a diametrical extension plane of the main cavity, so that deviation of the metal alloy takes place in a direction transverse to said diametrical extension plane. 
   
   
       11 . The process as claimed in  claim 10 , wherein said die-casting step comprises the step of introducing the molten alloy into the main cavity along a direction substantially parallel to the diametrical extension plane of the main cavity. 
   
   
       12 . The process as claimed in  claim 9 , wherein said deflecting element is provided in said main cavity in alignment relationship with a longitudinal extension direction of the secondary cavity. 
   
   
       13 . The process as claimed in  claim 9 , wherein the deflecting element is provided along the extension direction of an injection runner in front of a gate of the injection runner for entering the main cavity. 
   
   
       14 . The process as claimed in  claim 9 , wherein said deflecting element defines a recess in the disc-shaped body, disposed on the opposite side relative to said tailpiece.