Belt tightening device for open-end spinning machines

#The invention relates to belt tightening devices for open-end spinning machines with spinning units arranged side-by-side on a machine frame and provided, for example, with spinning rotors driven, via driving pulleys, by means of an endless belt. The belt is tightened by rolls supported in bearing boxes which are attached by means of overhanging swing legs to a holder on the machine, and associated with spring elements.

#With some devices of prior art, an endless belt such as referred to above will extend so as to contact a plurality of spaced apart driving pulleys with contact being effected by a plurality of tightening rolls which, on the one hand, serve in guiding the belt and which, on the other hand, act to force the belt against the driving pulleys of spinning rotors and/or fiber separating cylinders.

#Because of the relatively high rotation rates of modern open-end spinning machines, the tightening rolls and, consequently, the driving belt, are exposed to considerable vibration, in spite of the fact that the rolls are usually spring-loaded. In this regard, the mounting of tightening rolls on swing legs (as provided for, e.g., in Czechoslovak Inventor's Certificate No. 198 068) has proved inadequate or insufficient, because of the effects produced by belt vibration. These effects include wear or fatigue of the swing leg pivots, inaccurate belt guide positioning, fluctuations in the belt thrust power and, consequently, oscillations of the drive as a whole. Negative consequences of these effects include an increased noise level and a shorter lifetime of the mounting.

#Some preferred embodiments of the device according to the invention will hereinafter be described with reference to the accompanying schematic drawings, in which:

#FIG. 1 is a side view of a belt tightening device with a pair of tightening rolls attached to flat legs which at their opposite ends are secured to a holder affixed to the machine frame;

#FIG. 2 is a simplified side view of another embodiment wherein the holder is mounted for swinging or pivoting about a pivot provided in the machine frame;

#As can be seen in FIG. 1, belt tightening device of the invention is incorporated in a machine including a machine frame 1 to which a holder 2 is secured. To the upper and the lower side of said holder 2 there are affixed, by suitable connecting means, such as bolts with nuts, indicated at 4, two pairs of flat legs 31, 32, respectively, which carry at their free ends bearing boxes 5 of belt tightening rolls 6. The flat legs 31, 32 of each pair are spaced apart from each other at a distance "x" and extend along an endless belt for driving pulleys 8 of spinning rotors (not shown) of spinning units 9, either from both sides of the holder 2, or from one side only (FIG. 6).

#Each bearing box 5 of the tightening roll 6 is secured to the end of the pair of flat legs 31, 32 by suitable connecting means, such as bolts with nuts, indicated at 10. Each pair of flat legs 31, 32 can be secured to the holder 2 wither separately, or the individual members of the pairs, i.e., members 31 and 32, respectively, can be made of a single piece of material as shown in FIG. 1. In this embodiment, the pair of flat legs 31, 32 is made of leaf springs so that two rolls 6 can resiliently swing or pivot and are forced into contact with the driving belt 7 by a force resulting from an appropriate adjustment of the holder 2 relative to the belt 7 such that the flat legs 31, 32, as formed by leaf springs, are suitably prestressed.

#The holder 2 can either be fixedly attached to the machine frame 1, or, preferably, can be mounted for pivoting or swinging about a pivot 11 (see FIG. 2) provided on said frame 1, by means of a shock-absorbing liner 12 such as a "silent block".