In the case of known cable tie tools such as are known in principle from EP 0 428 116 A1, for example, a drive which actuates a cycle controller is provided. The latter serves for carrying out the various movements which have to be carried out by the cable tie tool in a controlled sequence in the context of an operating cycle. This includes in particular closing a gripping clamp of the tool, in which the strap for wrapping the object to be tied is guided, introducing the free strap end into the lock which is located at the rear strap of the former, and severing the projecting strap end, and finally opening the wrapping clamp.
These operational steps which have to be performed in a controlled sequence during the operating cycle also include tensioning the strap which is guided around the object to be tied by means of a tensioning installation. The latter serves for tightening the strap to a strap tension which is typically pre-determined. To this end, various types of tensioning installations are known, for example a tensioning installation having a tensioning roller which is provided with sharp teeth and engages in the surface of the strap which is composed of plastics (EP 0 432 477 A1). Once the strap reaches its pre-determined strap tension the traction force which is exerted by the teeth of the tensioning roller is no longer sufficient for onward movement, so that the strap is stationary and the teeth of the tensioning roller machine themselves into the surface of the strap. Even if the weakening of the strap material, which is invariably associated therewith, in practical terms is mostly of no further consequence, the abrasive wear which arises in the course thereof is indeed objectionable. This type of issue is avoided in another type of a tensioning installation in which the limit value of tension to be reached is set by means of a friction clutch (U.S. Pat. No. 4,610,076 A). In the case of such a friction clutch there is the issue of reduced reproducibility as a result of wear. Thus, while the abrasive wear as arises in the first mentioned solution is indeed avoided, uniform quality of strap tension does suffer in this case.
USPTO Backgrounds
USPTO Backgrounds