A Mathematical Model for Self-Twist Yarn Spinning Process

Abstract

A mathematical model is established for self-twist spinning process by applying laws of fluid mechanics (i.e. mass conservation and momentum conservation). The motion curve of the convergent point was determined and the convergence point was decided by densities and velocities of two fed-in strands and the resultant self-twist yarn, independent of their mechanical properties. The experimental verification proves that the motion trajectory of the convergence point reaches a better agreement with the theoretical trajectory. The results provide general way to study the self-twist yarn spinning process and optimize the process parameters.

Isometric fiber distribution in the roller drafting zone

“…The arrangement of the fibers in the yarn greatly influences the performance of the yarn, and the drafting in the spinning process directly affects the arrangement of the fibers in the yarn. 2,3 A feasible scheme to meet the challenge is to understand the motion state of fibers under different drafting parameters, such as the fiber type, fiber length, roller-setting (the distance between back nip and front nip), draft ratio (the ratio of front roller speed to back roller speed), doubling number (the number of input slivers), and sliver linear density. [2][3][4] The motion state of fiber depends on the force acting on the fiber.…”

“…2,3 A feasible scheme to meet the challenge is to understand the motion state of fibers under different drafting parameters, such as the fiber type, fiber length, roller-setting (the distance between back nip and front nip), draft ratio (the ratio of front roller speed to back roller speed), doubling number (the number of input slivers), and sliver linear density. [2][3][4] The motion state of fiber depends on the force acting on the fiber. In a drafting zone, two pairs of rollers with different speeds, the front rollers with fast speed and the back rollers with slow speed, grip the fiber sliver, and the force acting on fiber is affected by the contact probability with fast-moving and slowmoving fibers in addition to the fiber characteristics and the pressure force applied on the fibers.…”

“…In a drafting zone, two pairs of rollers with different speeds, the front rollers with fast speed and the back rollers with slow speed, grip the fiber sliver, and the force acting on fiber is affected by the contact probability with fast-moving and slowmoving fibers in addition to the fiber characteristics and the pressure force applied on the fibers. 2,5 Fastmoving fibers mean that the fibers are moving at the front roller speed and, similarly, slow-moving fibers mean that the fibers are moving at the back roller speed.…”

Pressure distribution in the drafting zone measured by film pressure sensors

“…As mentioned above, the distribution of the frictional force can be represented by the pressure on the drafting strands in the drafting zone, assuming that the friction coefficient is the same everywhere. 18 Therefore, pressure sensors are considered for measuring the pressure distribution. Compared with other transducers, film pressure sensors have high accuracy and strong anti-interference, and are widely used in many fields, such as transportation electronics, 19 industrial control, 20 geotechnical construction 21 and other related fields of pressure measurement.…”