Detailed Study About Picking On Plain Power Loom ? What is picking? Motin of Weaving? Picking detailed study? Picking mechanism? Picking components

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Picking is an essential operation in the weaving process, responsible for inserting the weft yarn across the warp threads. On plain power looms, picking mechanisms are designed to deliver a smooth and efficient weft insertion without damaging the warp or the weft yarn. Here is a detailed study of picking on plain power looms, covering the components, working principle, and key considerations.

1. Picking Mechanism Overview

The picking mechanism on a plain power loom is a mechanical system that propels the shuttle containing the weft yarn across the warp shed. The process involves precise timing and control to ensure efficient weaving.

Key Functions:

  • Propel the shuttle through the shed.
  • Maintain accuracy in weft placement.
  • Avoid damage to the shuttle, yarn, or loom components.

2. Components of Picking Mechanism

The picking mechanism primarily consists of the following components:

a. Picking Stick:

  • A flexible lever attached to the loom frame.
  • Transfers force to the shuttle to propel it across the shed.
  • Usually made of wood or other flexible materials.

b. Picking Arm (Lever):

  • Connects the picking cam to the picking stick.
  • Translates rotational motion into linear motion.

c. Picking Cam:

  • A specially designed cam mounted on the bottom shaft of the loom.
  • Converts the rotary motion of the bottom shaft into a striking motion.
  • Determines the timing and intensity of the pick.

d. Picking Shoe:

  • A component that connects the picking arm to the picking stick.
  • Helps deliver a smooth transfer of force.

e. Shuttle and Shuttle Box:

  • The shuttle carries the weft yarn and travels through the warp shed.
  • The shuttle box holds the shuttle at the end of each pick and cushions its impact.

f. Buffer Spring:

  • Absorbs the shock generated during the picking motion.
  • Ensures smooth functioning and minimizes wear and tear.

3. Working Principle of Picking on Plain Power Loom

The picking mechanism is driven by the bottom shaft of the loom. Here's how it works step-by-step:

a. Formation of the Shed:

  • The heald shafts separate the warp threads, creating a shed for the shuttle to pass through.

b. Activation of Picking Cam:

  • As the bottom shaft rotates, the picking cam engages with the picking arm.

c. Motion Transfer:

  • The picking arm transfers the force to the picking stick.
  • The picking stick flexes and snaps back, propelling the shuttle through the shed.

d. Shuttle Motion:

  • The shuttle travels at high speed, carrying the weft yarn across the shed.
  • The shuttle enters the opposite shuttle box, where it is cushioned and prepared for the next pick.

e. Repetition:

  • The process repeats alternately for both sides of the loom (left and right shuttle boxes).

4. Timing and Adjustments

Accurate timing of the picking mechanism is crucial for smooth loom operation. Misalignment or improper timing can lead to:

  • Shuttle fly-out (shuttle leaving the shed incorrectly).
  • Warp yarn breakage (due to shuttle collision).
  • Irregular weft insertion.

Adjustments:

  • Picking Timing: Ensure the cam engages at the correct angle of rotation.
  • Picking Force: Adjust the tension in the picking stick and buffer spring to control the shuttle speed.
  • Shuttle Box Position: Align the shuttle box to avoid misplacement or damage to the shuttle.

5. Types of Picking Mechanisms

a. Cone Over Picking:

  • Uses a cone-shaped picking cam.
  • The picking arm pulls the picking stick, which strikes the shuttle.
  • Commonly used in older plain power looms.

b. Cone Under Picking:

  • Similar to over-picking but the picking arm pushes the picking stick from below.
  • Offers better control and reduces shuttle fly-out.

c. Direct Picking:

  • Directly connects the picking cam to the shuttle.
  • Simplified mechanism, but less common in plain power looms.

6. Common Problems and Remedies

a. Shuttle Fly-Out:

  • Cause: Excessive picking force or misaligned shuttle box.
  • Remedy: Reduce the picking force and realign the shuttle box.

b. Irregular Weft Insertion:

  • Cause: Uneven shuttle speed or worn-out picking components.
  • Remedy: Replace worn-out parts and adjust the picking mechanism.

c. Warp Breakage:

  • Cause: Improper shed opening or shuttle striking warp threads.
  • Remedy: Correct the shed timing and picking alignment.

7. Maintenance of Picking Mechanism

Regular maintenance ensures the efficiency and longevity of the picking mechanism:

  • Lubrication: Apply oil to the picking cam and pivot points.
  • Inspection: Check for wear and tear in the picking stick, cam, and shuttle.
  • Replacement: Replace damaged components like springs or picking sticks.
  • Alignment: Regularly check the alignment of shuttle boxes and picking parts.

8. Efficiency Considerations

  • Optimal Picking Force: Prevents shuttle damage and ensures smooth weaving.
  • High-Quality Components: Use durable materials for picking sticks and cams.
  • Skilled Operators: Trained operators can quickly identify and fix picking issues.

By understanding the picking mechanism on plain power looms and maintaining proper adjustments, smooth and efficient weft insertion can be achieved, reducing downtime and improving fabric quality. 


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