Study on the Crochet warp knitting machine.

 Experiment Name: - Study on the Crochet warp knitting machine.

Introduction:

The warp knitting machine is a knitting m/c where the loops are formed in course wise direction and the fabric produced is in open width form. In Tricot warp knitting m/c compound needles are used. The warp yarns are feed to the needles through guide bars using shogging and swinging motion.

Objectives:

*      To get clear concept about the driving mechanism of crotchet knitting machine.
*      To know the functions of different parts of the machine.
*      To know about the different motions of the machine.
*      To know different parts of the machine.
*      To improve our technical knowledge.

Specification of the machine:

Ø  Company: DAH HEER Industrial Co. LTD.
Ø  Brand: DAHU.
Ø  Origin: Taiwan.
Ø  Model No: L
Ø  Size: 15 G

Main parts:

Motor
Main shaft
Size lever
Shogging motion lever
Weft yarn guide bar
Warp yarn guide bar
Needle bar
Needle
Pressure roller
Take up roller
Ratchet wheel

Machine description:

The machine is driven by an electric motor. Motion is transferred to the machine parts by gear and toothed belt. Here weft yarn guide bar gives to and fro motion and shogging motion. Shogging motion lever give motion to the weft yarn guide bar. Shogging motion is driven from motor by main shaft. Needle bar and warp yarn guide bar also give to and fro and shogging motion by the same mechanism. Take up roller has ratchet wheel, by which take up roller gets motion from the motor by pushing pawl and some mechanism.

    Fig: Crochet warp knitting machine.

Features of crochet machine:

1.    On crochet machines, the warp chains are separate from the weft inlay and it is the latter threads that join the chaining Wales to each other.
2.    A single horizontal needle bar whose simple reciprocating action can be used to operate individually- tricked latch, carbine or embroidery needles.
3.    The patent or carbine bearded needle is used for fine structures and has a sideways crimped beard placed in a permanently- pressed position.
4.    No sinker, instead a fixed hold back bar is fitted in front of the knock over verge to prevent the fabric moving out with the needles.
5.    Closed lap pillar stitches and inlay threads controlled and supplied as separate warp and weft respectively.
6.    Each needle is lapped from below by its own warp guide, which is clipped to a bar, whose automatic one needle overlap and return and under lap and shog is fixed and is controlled from an electric cam whilst it’s upwards and downwards swing is derived from a rocker shaft. The warp yarn is often placed low at the front of the machine.
7.    The weft yarn often placed above and towards the back of the machine, supplying the carrier tubes, which are clipped to the spring-loaded inlay bars.
8.    There are usually up to two warp guide bars and up to 16 weft inlay bars, which may be electronically controlled.
9.    The weft inlay bars may rather be electronically-driven or mechanically controlled in the traditional manner by chain links or levers. The choice is governed by the requirements either of long complex pattern repeats and quick pattern changes as in sampling, or for simple structures and long production runs.
10. The knitting widths of crochet machine may vary between 16 and 122 inches (400 and 3100 mm).
11. Gauge, often expressed in needles per centimeter, are between 2 and 10 (E5 to E24).
12. Machines run at speeds between 200 and 350 courses per minute.
13. Crochet machines can process a range of filament yarns from 20 dtex to 1000 dtex.
14. The warp yarn is often placed low at the front of the machine.
15. Special attachments are available for producing fancy effects such as cut or uncut fring edges, pile, braiding and snail shell designs.
16. Crochet machines, with their simple construction, ease of pattern and width changing, and use of individual yarn packages or beams provide the opportunity for short runs on coarse, or fine-gauge fancy and open-work structures and edgings, as well as the specialist production of wide fancy fabrics or narrow elastic laces.