Rieter

The construction of the nipper assembly

Index

The nipper assembly (Fig. 40) is of enormous importance to the design of a comber. The mass of the nippers must be accelerated and decelerated back to rest twice per nipper cycle (up to 7 times per second in modern machines). A low-mass nipper assembly – for example, made of aluminum alloy – is therefore advantageous. Also, the nipper assembly has to clamp a relatively thick lap batt (up to 80 ktex) firmly and evenly. The nipper plates themselves must therefore be made of steel (at least the clamping region), and the upper plate must be stiff while the lower plate is slightly springy. The upper nipper is mounted so that it can pivot on the lower nipper on pivot axis (a), and can therefore be raised and lowered. Two springs (8), one each to right and left of the nipper assembly, generate the required contact pressure for the nipper closing. The so-called bite must have a special form, as illustrated in Fig. 41. The nose (n) is designed to press the fiber fringe downward during clamping, so that the fringe cannot escape the action of the circular combs.

Detaching distance is also very important. On old combers the distance between the feed rollers within the nipper plates and the detaching rollers (in their nearest position) was too wide, strictly speaking the distance between the feed roller and the nipper mouth. This always resulted in slightly uncontrolled fiber extraction during the combing and detaching operation. Rieter solved this problem in a simple way by shifting the feed roller closer to the nipper mouth, and improving web guidance within the nipper installation by means of a special guide plate at the feed roller (Fig. 40, 1). This arrangement saves quite a considerable amount of good fibers.

Fig. 40 – The nipper suspension

Fig. 41 – The form of the nipper bite

Fig. 42 – The nipper support