Ranishka Yeashan
University of Moratuwa, Sri Lanka
Email: ranishkashn7@gmail.com
Introduction:
The Draw Frame is an important machine of the spinning mill because it also magnifies the yarn. Quality of yarn is directly related to the quality of Draw Frame Sliver, so the recent developments are carried out produce better Draw Frame sliver. There are some common developments which are evolved such as Autoleveller, Can Changing systems, suction devices etc. These are developing day by day to be more precise by means of electronic and mechanical improvements.
Fig: Autoleveller Draw Frame TD-10 Trützschler
Parameters of Modern Draw Frame:
1. High production rate – up to 1000 m/min delivery speed
Followings are some of recent developments in draw frame
Auto break draft setting – Incorrect break draft increases yarn U%. When there are imperfections and neps, the total draft does not affect yarn quality much. So break draft plays a very significant role in yarn quality and must be set correctly. In Trutzschler new draw frames has this Technology and it optimize the sliver by estimating the corresponding values of the break draft merely in one minute and takes important parameters, like fibre-fibre friction, fiber to metal friction, etc and calculate the break draft.
Fig: Drawframe and lap machine combined
CLEAN coil – The deposition of spin finish on the underside of the coller plate of draw frame when processing MMF leads to displacement of the sliver layer in can. To avoid this, the coller has to be cleaned frequently resulting in production loss. Rieter has patented a coller plate that has honeycomb like surface and claimed to reduce cleaning frequency from 2 to 3 hours to 1 – 3 days depending upon the type and quantity of finishing agents.
Pneumatic Pressure Head for the drafting rollers. This technology can control the pressure for sliver automatically and from that better fiber control can be achieved.
Tension measuring system – When the card sliver is fed to the draw frame, there is a long path to travel. So on way there will be tension variations due to friction forces and weight of the sliver. To avoid these tension variations there are tension measuring sensors to detect and adjust the roller speeds according to it.
Short-term auto levelers – In principle, leveling takes place in the entire speed range of the drawframe. Even when reducing speed before and during run-up after a can change, short-term leveling (SERVO DRAFT) remains in operation. Due to this each meter of draw frame sliver has its optimum quality.
Use a camera to monitor the sliver quality – This is used to monitor the output sliver behalf on quality aspects such as fiber arrangement, fiber imperfections and irregularities. This is done by using a camera which capture images of the output sliver and compared with the references by means of image processing techniques. When there is an imperfection, the machine is automatically adjusted to eliminate by varying the machine speed etc.
Fig: Use a camera to monitor the sliver quality
Simple and automatic adjustment of drafting zone widths – The drafting system rolls are precisely positioned on parallel guides. Since the nip distance can be set by reading on a dial, it is not necessary to use any gauges. Top roll support, top rolls and bottom cylinders are firmly connected to each other and are automatically adjusted as well. Due to a special belt guide, it is not necessary to tension again the belts after readjustment.
Use of microwave sensors – this is used in auto leveling to determine band mass of an elongated, substantially non twisting fiber structure. This is used the moisture content of the sliver as the measuring principle.
Thread monitor and a slubbing clamping device – In this amount of light transparency through the sliver is monitored. To do this principle, there are photo cells to capture the light form the light source. There will be a shadow (light intensity variation) which is generated according to sliver and it is monitored and processed through high level of technology. When there is a thick place the transparency of light will be lower and it is identified form the photo cell. When a sliver slub is monitored, the back rollers are clamped for a instant time and eliminate the slub.
Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. Mr. Kiron is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.
Very detailed and informative blog! A must read article for people who are closely associated with the textile and spinning industry. Great Job!