Raschel Machines Overview

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Questions and Answers

What is the primary function of the tension bar in the raschel machine?

To hold the fabric in place during knitting

To control the speed of the knitting process

To guide the needles in their movement

To maintain tension in the warp threads (correct)

What materials are the guides on the raschel machine made from?

Lead

Plastic

Steel (correct)

Aluminum

In what part of the raschel machine are latch needles typically found?

Guide bars

Trick plate

Sley bar

Needle bar (correct)

What role does the sinker bar play in the knitting cycle?

It holds the fabric down during knitting Signup and view all the answers

What is the purpose of the trick plate in the raschel machine?

To ensure precise knocking-over of stitches Signup and view all the answers

What is the gauge of the machine related to?

The number of needles per 25 mm Signup and view all the answers

How often do pattern bars in the raschel machine typically require a thread?

Every two to four inches Signup and view all the answers

What happens during the clearing phase of the knitting cycle?

The needle bar rises from knock-over Signup and view all the answers

What is the primary function of the guide bars in a raschel machine?

To control pattern repeat intervals Signup and view all the answers

What distinguishes latch needles used in a raschel machine?

They act automatically and self-close during knitting Signup and view all the answers

How are sinkers arranged in the raschel machine?

They are attached to the sinker bar and move during the cycle Signup and view all the answers

What is the purpose of the fabric tension rollers in the raschel machine?

To maintain the tension of the warp threads Signup and view all the answers

In what scenario would the latch wire interfere with the knitting process?

When the stitch loop slides downward Signup and view all the answers

How is the motion of the sinker bar described during the knitting cycle?

Forward and backward at specific intervals Signup and view all the answers

What is a key feature of the trick plate in a raschel machine?

It ensures stitches are knocked-over accurately Signup and view all the answers

What role do the ground beams serve in the raschel machine?

They support the guide bars during operation Signup and view all the answers

Study Notes

Raschel Machines

Raschel machines are a type of knitting technology.
They are used to produce a variety of fabrics, including lace, and others.
Images show different models of Raschel machines.
Machines have different components, including ground beams and pattern beams.
Access to these beams is from front, top and back.
Tension bars are present (one for each warp thread) to maintain tension.
Guide bars and levers, along with a sley bar, are essential parts.
Knitting elements include guides, sinkers, needles, and latch needles and trick plates.
Fabric tension rollers and a fabric batch roller are also parts of the machine.
The machine has a main drive for the cam shaft.
The machine has warp tension rails, knitting elements, and fabric take-up rollers, as well as a fabric roll.
The machine's bed includes a main eccentric shaft driving other components.
The different warp counts are mentioned (1, 2, 3, 4).

Knitting Elements

Guides are steel pressed blades with a hole, cast as a unit (25 mm wide) and screwed to the guide bar.
For ground structures, the front two guide bars suffice.
Pattern bars have finger guides and accommodate up to many guide bars.
The guide bars have threads at each repeat every two, three, or four inches.
Needles are latch needles that operate independently.
They come in 25 mm or 50 mm widths, mounted on a needle bar.
The number of needles per 25 mm depends on the gauge of the machine (e.g., 14, 18, 28, 36, or 48).
Sinkers are thin metal blades, protruding between needles from the rear.
They are attached to a sinker bar, moving back and forth during knitting cycles.
The trick plate, also called the knock-over comb, is a vertical plate spanning the machine's width.
It is made of thin punched metal blades.
Needles move up and down between these blades.
Blades help ensure precise stitch knocking over, particularly for long under-lapping.
Latch wires are thin, cylindrical wires across the machine just behind the needles.
They prevent latch needles from closing prematurely during stitch formation.

Knitting Cycle

Holding Down: Guide bars are at the front, completing their underlap shogging. The sinker bar holds the fabric down, while the needle bar begins to rise after the knock-over.
Clearing: Needle bar rises to maximum height, old overlaps slide down the stems, and latches are opened. Latch wires prevent latches from flicking. The sinker bar pulls back to permit guide bar over lapping.
Overlap: Guide bars swing to the back of the machine, shogging for the overlap.
Return Swing: As guide bars return to the front, warp threads wrap into the needle hooks.
Latch Closing: Needle bar descends, old overlaps contact and close latches; trapping new overlaps. The sinker bar then moves forward.
Knocking Over and Underlap: The needle bar continues to descend, its head passing below the trick-plate. The new overlap is drawn through the old, which is cast-off. Sinkers advance over the trick-plate, and guide bar underlap shogging begins.

Jacquard System

The Jacquard system is depicted in diagrams, showing its mechanisms.

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Description

This quiz covers the essential components and functioning of Raschel machines used in knitting technology. Explore various elements such as guide bars, tension bars, and fabric rollers. Enhance your understanding of this specialized machinery and its applications in fabric production.