The Mayer Jacquardtronic multibar lace raschels

The traditional mechanical verdol jacquard control, previously described, is slow, cumbersome and time-consuming when changing designs. On the latest electronic machines, the jacquard head has been replaced by a computer control that is simply linked by a cable to the combined selection element and jacquard guide, which are one unit. There are no jacquard harness cords for lifting and guide displacement which would restrict the use of the conventional guide bar swinging movement.

At first, Karl Mayer used electro-magnets to obtain the jacquard deflection movement; this has now been replaced by piezo technology (Fig. 28.15a and b) [4]. When

Piezoelectric Jacquard
  1. 28.15 a. jacquard segment of 16 or 32 segments [Karl Mayer]. b. Jacquard element [Karl Mayer].
  2. 28.15 a. jacquard segment of 16 or 32 segments [Karl Mayer]. b. Jacquard element [Karl Mayer].
Textronic Lace

Fig. 28.16 Leaver's lace effect produced on a Textronic raschel lace machine [Karl Mayer

Textronic].

Fig. 28.16 Leaver's lace effect produced on a Textronic raschel lace machine [Karl Mayer

Textronic].

an electrical voltage is applied to a piezoelectric material, it expands or contracts as a function of the polarity. The resultant change in length is directly proportional to the applied electrical voltage. Each jacquard guide has a piezoelectric ceramic strip on either side that positively moves the guide one needle space left or right when required. The possibility of being able to transmit two different control signals during one knitting cycle enables selective displacement of both the overlap and the underlap stitches to be achieved.

With this arrangement, knitting speeds can be increased by up to 50 per cent and power consumption is reduced. There is a quicker reaction and a greater range of guide bar shogging possibilities.

Three MRPJ Jacquardtronic machines have been developed with 25, 43 and 73 guide bars in gauges E 18 and E 24. The 43-bar machine has a production speed of 420 courses per minute and a pattern repeat area of 168 needles and 14000 courses.

The jacquard bar can be positioned behind the pattern bars so that three-dimensional patterns can be produced. On the model MRPJ 73/1 [5], the ground bar is in position 1, there are then 70 pattern bars, a split piezoelectric jacquard bar in position 72, and an elastane guide bar in position 73. The guide bars are divided into 18 shogging rows (displacement lines) of which two can form stitches. By positioning the pattern bars in front of the jacquard bar, three-dimensional relief motifs can be produced.

The guide bars are shogged by two computer-controlled digital pattern drives. The ground bar, jacquard bar and even-numbered pattern bars from 4 are controlled from the right side of the machine. Odd numbered pattern bars from 5 are con-

Machine Textronic
Fig. 28.17 Textronic MRPJ 59/1/24 raschel lace machine [Karl Mayer].

trolled from the left side. The control for guide bars 2 and 3 via the mechanical overlapping mechanism is located on the left side of the machine.

The latest 'Textronic' fall-plate multi guide bar raschel lace machines use new technology to produce 'Leaver's lace' quality fabrics. Shadow and filler yarns can be used as well as thick contour yarns (gimps or liners) (Fig. 28.16).

One of the models, MRPJ 59/1/24 (Fig. 28.17), has 59 guide bars arranged in 14 shogging lines. Twenty-four pattern bars are in 4 shogging lines in front of the fallplate and are thus controlled by it. There are then two pattern guide bars with mechanical overlaps, a stitch-forming ground guide bar, one piezo jacquard bar for inlay, 30 pattern inlay guide bars in 5 shogging lines and one elastane yarn guide bar.

Karl Mayer have an individual yarn selection device that removes yarns when they are not required so that there are no floats carried in the ground between one motif and the next. As soon as the yarns are needed again for patterning, they are reintroduced after having been cut and trapped.

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