Views: 2 Author: Site Editor Publish Time: 2022-07-29 Origin: Site
At present, the automatic knitting machine generally adopts computer control technology. It uses electronic needle selection technology to control the flat knitting machine to select single needle needles, thereby forming various colors. In addition, some old machines also use electronic needle selection to replace the old mechanical needle selection by expanding the possibility and practicability of their patterns.
During our investigation, we found that many manufacturers are developing and transforming the needle selection system by themselves. Due to the improper selection of the needle selector, the pattern is often disordered and deformed, and it may even cause the wrong action of the mechanism to damage the mechanical structure. Based on development and experimentation, some research is carried out on several factors that affect the reliability of needle selection of the automatic knitting machine needle selector, and corresponding measures are put forward to ensure the reliability of needle selection.
1. The role of the needle selector
The structure of most automatic knitting machine needle selection control systems is electromagnetic needle selection. Here, the automatic knitting machine adopts an upper and lower two-level computer structure. The upper computer is an industrial computer, which is mainly responsible for management and monitoring; It is responsible for controlling the needle selection of the needle selector according to the synchronization signal and the control signal of the host computer.
It can be seen that the needle selector is a transducer that sequentially drives the needle selection mechanism according to the electrical signal combined with the fabric pattern and is an executive element used by the automatic knitting machine control system to implement needle selection control. Therefore, its performance is good. Bad will directly affect the accuracy and reliability of needle selection.
2. Types of needle selectors
At present, the commonly used needle selectors are divided into the electromagnetic type and piezoelectric type in terms of the action principle. Piezoelectric needle selectors use piezoelectric ceramic materials as conversion elements and use the pulse signal sent by the controller to act on the pressure. On the electrical element, the inverse piezoelectric effect of the piezoelectric material is used to bend the piezoelectric element to a pre-memorized shape for needle selection.
Another type of needle selector is to use currents in different directions to the electromagnetic spiral tube to change the polarity of the head end of the electromagnetic spiral tube correspondingly or to use in conjunction with a permanent magnet, relying on the attraction and repulsion between the electromagnet and the permanent magnet. To realize the swing of the needle selection head, that is to use the needle pressing method to realize the needle selection or directly control the needle selection of the needle selector through the change of the polarity of the electromagnet so that the knitting needles go to different tracks, and the needle selection method is completed by the needle copying method.
Compared with the two methods of needle selection, the piezoelectric needle selector has the characteristics of fast response and less heat. Still, it is slightly inferior in terms of the force of the element, shock resistance, vibration, etc., and it is easy to cause the piezoelectric element to lose its memory. Therefore, it is used more on circular knitting machines to ensure fast response and adapt to multiple channels. At the same time, the power consumption and heat generation of the needle selector will not be too large. It is more advantageous to use electromagnetic needle selectors on flat knitting machines. The main reasons are: :
①Flat knitting needle
It is thicker, and the yarn tension is more significant during knitting, so the needle selector is subjected to a greater force. The electromagnetic needle selector can withstand more significant force and has good anti-vibration and long service life.
② The control action of the flat knitting machine is complex, and the precision of the coordination between each part is high so that the electromagnetic needle selector can take advantage of its reliable action. Therefore, it is better to use the electromagnetic needle selector in the experiment.