Arithmetical calculations for weaving students by Neville H & Neville H. Yarns & cloth

Author:Neville, H & Neville, H. Yarns & cloth
Language: eng
Format: epub
Tags: Weaving, Cotton weaving
Publisher: Blackburn [Great Britain] : Standard and Express
Published: 1904-03-25T05:00:00+00:00

Rule. — (c) Picks per inch multiplied by Length ».f piece in yards divided by counts off weft, equals inches to be added to cloth length of warp. This is only applicable to plain cloth.

Example. —A piece of 40 yards long has 60 picks per inch of 40's weft : What allowance must be made for warp contraction?

GO x 40-=-40 = GO inches to be added to warp. This allowance is equal to 4. IG per cent., which, referred to the above table, shows a difference of .-'54 per cent, resulting from the two Rules for the same kind of cloth. This Rule, like the last, gives* increasing length allowances for increasing picks.

Rule. — (d) In dealing with several kinds of shrinkage, or contraction in plain cloths, Staub gives the following rule for what he terms '' Normal or Reciprocal " shrinkage : that is, shrinkage in which both sets of threads are deflected somewhat equally by their intersecting with each other. For his purpose he uses certain " constants " to which he gives the names, " co-efficients of skrinkage." These are,—for cotton and silk, 0.567 ; for wool, 0.88 ; for linen, 1.6.

(1.) For warp contraction :

Picks per quarter inch squared x coefficient

= per cent, for warp

Counts of weft used. contraction.

(2.) For weft contraction.:

Ends per quarter inch squared x coefficient

per cent, for weft

Count of warp used. contraction.

Example. —A cotton cloth has. to be made with 16 ends of 32's twist and 16 picks of 36's weft, per quarter inch : What per cent age of contraction is to be allowed?

(I.) 16 x IG x 0.567

— = 4.032 per cent, for warp contraction.

36

(2.) IG x 16 x 0.567

32

= 4.536 per cent, for weft contraction.

Staub recognises that these Rules give increasing length per centages of contraction for increasing picks, and proceeds to deal with the matter by other Rules in which he considers the sum of the diameters of the two threads intersecting with each other, on the principle that, the deflection of such threads can never exceed the sum of both diameters. But these Rules are too complicated for general use.

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