OBJECT: To study the working mechanism of draw frame.
OBJECTIVES OF DRAW FRAME:
* Equalizing cross sectional volume of sliver.
* Parallelizing the fibre.
* Dust removal.
Drafting is a mass reduction process. It is defined as,
“The reduction of weight per yard of sliver and increase in length is called drafting.”
“Attenuation of sliver without breaking is called draft.” MATHEMATICALLY:
TOTAL DRAFT ═ BREAK DRAFT × MAIN DRAFT
3rd 2nd front
Break draft main draft
Break draft is the draft between second and third rollers. Main draft is the draft between second and front rollers.
TYPES OF DRAFT:1. ACTUAL DRAFT: It is the ratio between material feed and material delivered. MATHEMATICALLY:
Actual draft ═ Length/Count deliveredLength/Count fed
2. MECHANICAL DRAFT:
It is the ratio between the surface speed of delivery rollers and surface speed of feed rollers. MATHEMATICALLY:
Mechanical draft ═ Surface speed of delivery roller Surface speed of feed roller DRAFT SETTING:
Draft can be set in the draw frame by changing the surface speed of feed roller and delivery roller and this is done by an arrangement of gears and lever. The upper gear is named “Q” while the lower gear is named “G”. The number of teeth of the two gears is changeable. DRAW FRAME:
WEB COLLECTING DEVICE
RUBBER COATED ROLLER
PARTS OF DRAW FRAME:
1. ROLLER ARRANGEMENT: This arrangement contains two types of rollers i.e. upper roller...