Method and apparatus for manufacturing a toothed belt

Abstract

The toothed belt is produced in a moulding cavity, which is defined by a rotating moulding wheel and an endless moulding belt, which is also rotating. For this purpose, the moulding wheel has a channel defined by lateral cheeks, in the base of which are provided recesses, which correspond to the teeth of the toothed belt. The moulding belt surrounds the moulding wheel over a proportion of its periphery and engages the lateral cheeks at that point. The polyurethane, of which the toothed belt is to consist, is injected into the inlet of the moulding cavity. Upstream of the inlet, “lost cores” are introduced into some of the recesses in the moulding wheel corresponding to the teeth in such a manner that they are embedded all around in the polyurethane. After finishing the toothed belt the “lost cores” can be removed. Passages remain which can be used, for instance, for mounting fastening elements.

1 . Toothed belt of plastics material, which has a breadth and is provided with teeth and with a “lost core” in at least one of is teeth, 
 wherein the “lost core” extends substantially over the breadth of the toothed belt and is embedded all around in the plastic material of the toothed belt over at least a portion of its length.    
     
     
         2 . Toothed belt as claimed in  claim 1 , 
 wherein the teeth of the toothed belt have a respective crown surface and the toothed belt has a rear side and wherein the “lost core” has at least two webs, which extend from the crown surface of the associated teeth to the rear side of the toothed belt.    
     
     
         3 . Toothed belt as claim in  claim 2 , 
 wherein the “lost core” is rod-shaped.    
     
     
         4 . toothed belt as claimed in  claim 3 , wherein the rod-shaped “lost core” has a round cross-section.  
     
     
         5 . Toothed belt as claimed in  claim 2 , wherein at least two of the webs are matched to the tooth shape.  
     
     
         6 . Toothed belt as claimed in  claim 2 , wherein the “lost core” has a web at each of its lateral ends.  
     
     
         7 . Toothed belt as claimed in  claim 1 , wherein the “lost core” consists of a brittle material, which does not bond with the plastic material of the toothed belt.  
     
     
         8 . Toothed belt as claimed in  claim 2 , wherein the “lost core” consists of a material having sliding properties which are better than those of the plastic material of the toothed belt.  
     
     
         9 . Toothed belt as claimed in  claim 1 , wherein the rear side of the toothed belt is untoothed and ground to size.  
     
     
         10 . Toothed belt of plastics material, which has a breadth and is provided with teeth having a tooth shape and with a “lost core” in at least one of its teeth, wherein the “lost core” extends substantially over the breadth of the toothed belt and is embedded all around in said plastics material of the toothed belt over at least a portion of its length, and wherein at least one fastening element is provided, which extends transversely over an untoothed rear side of the toothed belt and, after removal of the “lost core”, engages in lateral openings in the associated tooth produced by the “lost core” with two webs matched to the tooth shape and is held by a screw, which passes through the tooth and connects the webs.  
     
     
         11 . Toothed belt as claimed in  claim 10 , wherein the screw is constructed in the form of a predetermined breaking point.