Design & Development of a Modified Mobile Doffing System for Ring Spinning Machines

In ringframes, doffing is a labour intensive operation requiring 6 persons for 1008 spindles. In these days of severe labour shortage, already ringframes with link coners having inbuilt stationary automatic doffing system

are preferred despite high initial costs in new spinning mill projects resulting in 50% reduction in labour. Retrofittable stationary automatic doffing system is also developed by few manufacturers which cost about Rs.1500/ spindle and this system takes about 4 minutes to carry out the full doffing operation in 1008 spindle machine.  The prohibitive high initial cost of stationary doffer has led the development of a semi automatic mobile doffing system which has limitations such as 20 – 30% starting end breaks, missed doffs and need to press the cops in to proper position manually. 

In order to overcome the above mentioned drawbacks, SITRA has carried out suitable modifications as outlined below. 

  1. Yarn holding device is fitted on the spindle to hold the yarn at the time of restarting and the starting breaks are reduced to <5%.

  2. A setting gauge for the machine to achieve 100% doffing of cops is designed

  3. To improve alignment /positional stability, the rail made of square pipe has been used

  4. A cam driven mechanism has been designed to press the cop on the spindle. The performance of the pressing device is under evaluation

Performance evaluation of the modified mobile doffing system is being conducted in a local mill on a ring spinning frame.