The feed-through feedback device is a system used on th […]
The feed-through feedback device is a system used on the warp knitting machine to accurately feed back the actual delivery value. Whether the feedback is accurate or not directly affects the quality of the warp-knitted product. In actual warp knitting production, the operator often thinks that the feedback value is the actual delivery value. However, in the experiment, we found that when the warp knitting machine is used for a certain number of years, its actual delivery volume does not match the feedback value of the delivery, resulting in feedback deviation. Therefore, when the warp knitting machine has a phenomenon of feedback deviation, it is an important problem for technicians to find a reason and propose a reasonable solution. A simple analysis of the influencing factors of the feedback deviation of the warp knitting machine is now made.
1 delivery feedback system
The feed-through feedback system of the high-speed warp knitting machine, the sensing roller is pressed against the warp beam by the pressure spring, and when the warp beam is rotated to send the yarn, the roller and the warp beam surface yarn move at the same linear velocity. The surface speed of the roller is transmitted to the encoder at the head end of the roller through the ratchet device in the roller arm. The linear velocity signal is processed by the encoder and transmitted to the microcomputer in the control box. After the signal is processed by the microcomputer, the delivery volume is displayed through the feedback interface. .
2 Force analysis of the yarn on the surface of the roller and the warp beam
The roller is pressed against the surface of the warp beam with a certain pressure. When the warp beam rotates, a relative movement tendency occurs between the yarn on the warp beam surface and the roller. The yarn gives the roller a forward friction force f. At the same time, due to the inertia, there is a backward resistance between the two. When f is greater than the resistance, static friction occurs between the surface yarn and the roller, v 1 = v 2 . (v 1 denotes the warp surface yarn speed, v 2 denotes the roller surface linear velocity, hereinafter the same as above) When f is less than the resistance, the yarn and the roller contact surface are slidably rubbed, and the roller slips on the warp beam surface, v 1 > v 2 . The feedback of the delivery is too small. As the weaving progresses, the outer diameter of the warp beam head is reduced, the torque of the compression spring becomes smaller, and the tangential force of the torsion spring becomes smaller as shown in Fig. 1, and the pressure of the roller on the surface of the warp beam is reduced. , f decreases. When f is less than the resistance, the roller slips, v 1 >v 2 , and the feedback is too small.