Nondestructive Test Technology Research for Yarn Linear Density Unevenness

Yarn linear density and linear density unevenness between fragments involve the mass and mass variation of yarn per unit length, which are important indices to reflect the uniformity of yarn thickness. Aiming at the shortcomings of the traditional testing method, which uses a yarn length tester to test these indices by counting length first and then cutting and measuring weight, a testing device that measures weight and counts length synchronously is designed and developed, so that the yarn can be continuous, recyclable, and reusable. Length counting is conducted by a length-counting disk connected to a photoelectric coded disk, and the result of length counting can be accurate to 0.01 m. The original skein frame with a perimeter of 1 m is replaced, so that the error caused by yarn overlapping is avoided. Through program control, the testing of a plurality of groups of linear density values can be completed at one time to calculate the linear density unevenness of different fragments of yarn, and the yarn can be led to a recovery spool through a yarn guide cylinder to form a new package. Polyester/viscose 65/35 blended yarn was taken as a test sample and subjected to statistical analysis using SPSS software. It is found that the results of the newly developed device are closer to the arbitration value; the whole experiment is completed at one time, which avoids the secondary error and reduces the labor intensity; and the raw materials can be recycled, which saves labor and raw material costs. The device has high value for industrialization and popularization.