Submitted to: Lecturer Daffodil International University

Submitted by: Asif Ahmed Tonmoy & Uttom SenID: & ; Sec: BCourse name: Yarn Manufacturing - II

Assignment topic:

 Date of Submission: 29.03.2016.

Engr. Md. Mashud Raihan

Details study on apron, condenser, spacer and top roller.

131-23-3505 131-23-3331

A typical rubber compound for the outer or inner layer of an apron contains the base polymer as well as between 10 and 15 different additives, which also affect the various physical and mechanical properties of the various aprons.

APRON

Basically, aprons made of synthetic rubber are made in endless tubular form whereas leather or synthetic leather aprons are made open in strips and subsequently glued together to form an apron. The advantage of the tubular construction is the lack of a seam. The apron is uniform along its entire circumference.

Aprons for use on ring spinning machines and roving frames are made of three layers; in some special applications used in the long staple spinning they only have two layers. It has a thickness of about 1mm and held taut by tensioning device

APRON

APRON

The length of the aprons also called as the cradle length is kept approximately equal to the staple length of the fibers. The cradles for different staple length are shown in Figure.

Cradle lengths according to the fiber length

Feature:• Condensers are mounted on a reciprocating

bar behind the drafting arrangement.• The second condenser is provided in break

draft field.• And the 3rd one is located in main draft field. Function:• Spreading sliver masses are condensed to

improve evenness and lead to drafting zone. Advantage: • Reduce the high fly level and hairiness of

roving.

CONDENSER

Condensers placed in the drafting zone help to prevent the fiber strand from spreading apart during drafting.

Condensers can be classified as feed (or inlet) condenser, middle condenser, and delivery (or floating) condenser (Figure).

Feed condenser is used just before the back pair of drafting rollers. The middle condenser is used near the nip of the middle pair of rollers and the third one is used just before the front pair of rollers.

CONDENSER

SPACERThe distance between top and

bottom aprons is maintained by a small component called "cradle spacer" or "spacer," which is inserted between the nose bar of the bottom apron and the cradle edge of top apron. The selection of spacer for a process depends on the hank of the sliver, break draft, and roving hank. Spacer size is 4 to 7 mm in accordance with roving hank.

Spacer size of different roving hanksRoving Hank Spacer Size X(mm)

Up to 1.0 7-81.1-1.8 6-71.8-2.5 4-6

2.5 & above 3-4

Advantages and disadvantages of reducing the spacer size

SPACER

TOP ROLLER

Top rollers are held strictly parallel to and in perfect alignment with bottom rollers. Top rollers covered with rubber cots play a significant role in the control of drafting

irregularities.

The hardness of top rollers is between 80° and 85° Shore, but the rollers over which the apron runs often have a hardness only slightly above 60° Shore. This permits better enclosure and guidance of the fiber strand during drafting.

The top rollers must be pressed with relatively high force against the lower rollers to ensure guidance of the fibers. 100- 300 N per roller is normally applied depending on raw material and volume of fibers.

The fiber or dust accumulation in the top roller neck should be cleaned frequently using picker gun.

TOP ROLLER

The top roller must be pressed with relatively high force against the lower rollers to ensure the guidance of fiber.

Pressure are in the range of 100 to 250 N per roller which may vary as per raw material and its volume.

Pressure is applied by spring pressure, pneumatic weighting, magnetic weighting.

TOP ROLLER