Beginning and ending zones of the preform

The difference in width between the two extremities can be obtained through more knitting sequences. One possibility is to produce some zones that will be subsequently removed. In these zones the evolution is successively changed from 1×1 rib to tubular jersey, specific to the sandwich structure. The use of two feeders for the tubular fabric (row 2) requires 1×1 rib evolutions on selected needles that present the disadvantage of larger floats. To avoid this situation, the 1×1 rib evolutions on selected needles can be maintained only for small zones, the rest of the working needles producing tubular evolutions (see Fig. 35). Such a variant presents the advantage of simplifying the knitting sequence and the process.

Beginning and ending zones of the preform

Fig. 35. Tie-in zone – from tubular to rib on selected needles (beginning zone)

Fig. 36 illustrates a fashioning solution for the beginning and ending zones. In this case, a number of incomplete rows are knitted with tubular evolution, using one yarn feeder. The groups of needles are successively introduced to work until all active needles are working. This way, the supplementary zones to be subsequently eliminated are cut out.

The number of incomplete rows will determine the slope of the inferior extremity. The slope of the superior extremity will be determined the same way, but the knitting sequence will be reversed. Regardless of the chosen variant, the number of rows knitted in the beginning zone is calculated with relation (1):

Подпись: (1)Nr = –

B

Where:

Nr – number of rows for the beginning and ending zones;

L – height of the beginning or ending zone, mm;

B – stitch height, mm.

The height of the beginning/ending zone is determined in the design stage, according to the specific dimensions of the wing; in this case 30 mm for the beginning zone and 25 mm for the ending zone. The calculated value is used to determine the groups of needles that will pass successively from one evolution to the other, or will successively start to work (2).

Nneedles

Rroup

Nr

Where:

Igroup – width of a group of needles;

Nneedles – total number of needles working in each bed; Nr – number of rows in the beginning/ending zone.

Beginning and ending zones of the preform

Fig. 36. Knitting sequence for the beginning zone