Rieter

Basic concept of tuft feed

Index

Fig. 91 – Material feed at the card

Fig. 92 – Tuft feed with a one-piece chute

Fig. 93 – Tuft feed with a two-piece chute

A distinction must be made between two basic tuft feed concepts:

  • one-piece chute without an opening system (Fig. 92);
  • two-piece chute with an opening system (Fig. 93).

In the one-piece chute, a column of material of a height that is somewhat variable over time is pushed forward toward the feed rollers. This form of chute is simple, uncomplicated, economical and needs little maintenance, but does not comply with the requirements of a high-performance card. In contrast to this chute, the two-piece chute is more complex and expensive, but delivers a more even batt with better opened material.

The upper half of the chute is a reserve chamber that serves to receive the material from the  blowroom and to separate the material from the air. In the lower portion, after an opening stage at the opening roller the quantity of material is held constant. This material is lightly compressed by compressed air or by vibrating plates in a continuous and even manner to form an even batt - an ideal feedstock. A distinction is also drawn between feed installations with open and closed distribution systems. In open transport systems, the ducting terminates after the last card. In closed systems, there is a circulation path through which excess tufts, which have not been taken up by any card, are returned to the distributor unit. If too much material is present on the circulation path, neps can be formed. This type of installation is also inflexible, since an established association of the cards with the blowroom installation cannot be changed. In all forms of pneumatic chute feed it is important that when operation of a card ceases, all compression of material in the chute is terminated, whether such compression is effected by compressed air or by the shaking of  a vibrating plate. Otherwise, material remaining in the chute will be over-compressed and when operation restarts the resulting sliver will be too heavy over a significant period.

Cards with pneumatic feed mostly require regulating equipment to maintain constant sliver weight.