tailieunhanh - Woven Fabric Engineering Part 5

Tham khảo tài liệu 'woven fabric engineering part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Importance of the Cloth Fell Position and Its Specification Methods 107 operation. Upon insertion of the sensor needle into the cloth it moves with the cloth and therewith measures cloth displacement while the loom is at rest. The sensor needle is attached to an actuation device capable of reciprocating the needle into and out of the cloth. The sensor needle is inductively coupled to a distance sensor which measures the needle displacement and therewith the displacement of the fell. In this manner fell displacement while the loom is at rest can be measured and before weaving is restarted the position of the cloth and therewith of the fell can be corrected k Godert 1996 . Using the photography system This test method was presented for measuring the cloth fell displacement during relaxation of fabric yarn combination on a tensile tester. The equipment consists of a CCD-camera a frame grabber and appropriate software. This study has been carried out on the tensile tester rather than on the loom where oscillations can hinder the efficient use of a camera. Fig. 6 shows the arrangement of the equipment. The camera takes one image per second during relaxation measurements. This image is sent to the frame grabber in the PC controlling the tensile tester. In this way the images are known as a grid the grid points being called pixels in which each pixel carries a light intensity value of the total image. In this digitized image rows of pixels are in the direction of the weft yarns and columns of pixels are in the direction of the warp yarns. At first the sum of the pixel values is calculated over the horizontal lines rows of the digitized image. Next values are filtered to eliminate noise. The results in a graph show the position of the weft yarns in the fabric clearly as peaks in the sum of intensity along the warp yarn direction Fig. 7 . Tensile tester Data t- controlling instructions Fig. 6. Test equipment for measuring the cloth fell displacement The .