Question 06 (Textile Engineering & Fibre Science)
Pressure bar is provided in a draw frame to
| (A) | Increase the pressure on the middle top drafting roller |
| (B) | Reduce the intensity of drafting waves in the drafted strand of fibres |
| (C) | Reduce the pressure on the middle top drafting roller |
| (D) | Reduce the formation of neps in the drafted strand of fibres |
[Show Answer]
B
Frequently Asked Questions | FAQs
What is the top roller in a drawframe?
In a drawframe, the top roller and pressure bar play important roles in the drafting process of converting the drawn sliver into a fine roving.
The top roller is a rotating cylinder that is covered with a rubber or metallic sleeve and is positioned above the drafting zone. Its main function is to grip the incoming material, i.e., the drawn sliver, and pull it through the drafting zone. The speed of the top roller is slightly faster than that of the bottom rollers, creating a controlled tension and draft between the two.
The pressure bar, on the other hand, is a stationary element located below the top roller and above the bottom rollers. It helps to maintain uniform pressure on the material passing through the drafting zone, preventing the top roller from pressing too hard on the bottom rollers and causing uneven drafting. The pressure bar also acts as a support for the top roller, ensuring that it maintains a constant and precise position during operation.
Together, the top roller and pressure bar create a controlled drafting process that helps to produce consistent, high-quality roving.