Rieter

Blending drawframes

Index

In the spinning process every doubling produces simultaneous blending – especially the 6-8 doublings on the drawframe. This blending intensity is adequate for processing cotton. However, if cotton and synthetics are to be processed together, operation of the normal drawframe will no longer be optimal, although blending is generally carried out in this way in Europe. Blending is good in the longitudinal direction, but is inadequate in the cross-section (see  Technology of Short-staple Spinning). Special blending drawframes have been available for a long time in worsted spinning and it is therefore not surprising that attempts were made to introduce them into short-staple spinning mills.

This machine (no longer offered for cotton) (see Fig. 21) had four preliminary drafting arrangements and one downstream drafting arrangement.
Each preliminary drafting arrangement processed a separate set of six slivers. The webs produced in this way were brought together on a table and fed to the downstream drafting arrangement. The sliver emerging from this point was coiled in cans.

Whereas three passages are almost always needed with normal drawframes (blending drawframe and two subsequent drawframes), two passages suffice when a blending drawframe is used (one normal drawframe followed by one blending drawframe). In addition to this advantage, and improved intermixing, a further favorable aspect should be mentioned, namely that each raw material component can be processed in a drafting arrangement of its own. However, the disadvantages are serious:

  • five drafting arrangements combined in one machine (setting, maintenance, etc);
  • complexity;
  • cost when 100% cotton is to be processed (when blended yarns are not required).

Fig. 21 – Principle of the blending drawframe