By: Qasem Heydari , M. Sc. Textile engineer, polytechnic university, Iran
Full yarn package doffing without breakage system is arranged on several Rieter open-end yarn machine such as Ru04, Ru14 and R36 but not on R20. In an open-end machine with 300 positions, doff number and subsequently number of splicing on the empty bobbin is more than one splice per 2 minutes or even one splice per 1 minute.
In many cases in several spinning mills, for much old and worked machine with low quality of raw material and down cotton sort, that has excessive yarn breakage, automatic doffing with robot ignored and it done manually and robot splice continuously in aim to increase of efficiency.
In this situation, if with supposing robot splicing time summing robot moving time about 30 seconds averagely and 2-4 number of end down in every package, 25-45% of robot splicing efficiency spend to splicing of the empty bobbin. If robot spends this time and efficiency only for splicing of breakage yarn in the middle of the bobbin, machine efficiency increased extremely. In continuing one approach for doffing without yarn breakage on R20 presented.
2- Method and experience:
In this method, the following space should be doing:
1- Supplying of air suction in every spinning position.
2- Machine adjusts.
3- Operator learning.
2-1 Supplying of air suction in every spinning position
This suction system is like the conventional suction system in Rieter-Ru04, Ru14 and R36. For this reason, we can use one overall plastic pipes with Ru04 supplements for divide suction on every section and easily open and close for save suction power.
2-2 Machine adjust
The requisite setting is:
1- Inactive of automatic doffing.
2- Increasing of waiting time to robot to doff while LED is 2-on. This is conventionally 1 kilometre of yarn length that could increase (like 10 kilometres) related to yarn production speed, operator performance and maximum ignorable yarn length tolerance.
3- Change the yarn length of manually doffed position from maximum to zero. The operator doesn’t do this not for every 1 position. He can go to machine headstock for such as 10 positions.
2-3 Learn operator how do doff without breakage
The operator has to learn and do the following actions:
1- Put up a cradle and at the same time, guiding yarn from on doffing bobbin to the suction duct.
2- While the spinning process is running, spinning yarn should break from full package.
3- Change empty bobbing with full package
4- With pressing of a key, change yarn monitor LED from 2-on to red-blinking statues mode
5- Put yarn from the suction duct and delivered it to an empty cone.
As so prohibition of yarn fault creating is better than yarn fault emitting or cleaning, the prohibition of yarn breakage at doff time is better than broken yarn splicing. This subject is on attention in most Rietter machines open end; but in R20 it is ignored, so we supply air suction for that machine.
Machine efficiency compared before and after arranging of suction for yarn count 6 and 30 Nm Iranian cotton, no automatic robot doffing, no automatic robot splicing and manually doffing with help of air suction without necessity of yarn breakage and no need robot splicing.
For coarse 6 Nm with more bobbing doffing, this method not work because of increasing of operator labor and he don’t have enough time for checking of not spliced position. But for fineness 30 Nm with excessive yarn breakage, the efficiency 20%increased and operator activities decreased because of saving of robot time for break yarn splicing.
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