Mechanism Of
Circular Warp Knitting Machine
There occurs a patterning mechanism in every novel circular knitting machine. This procedure supplies threads to the needles at the suitable points of the knitting cycle, usually after a particular sequence. It helps to create the required knitted pattern. A knitting pattern comprises of several underlaps of varying lengths. Every underlap pursues an overlap which wraps the thread over the needle. The patterning mechanism concepts used previously, i.e. by Borenstein in 1986 and Ragosa in1990 were all mechanically operated. These procedures used to employ two patterning rings driven by open face cams and provided us with a maximum pattern length equal to twelve machine cycles. Due to the limited space, there occurred a curb on the number of cycles. For carrying out several machine cycles in the pattern process, we need to fix a larger cam in the knitting machine. But, the problem was that a restricted space was available for accommodating the cam, so a bigger size component can't be attached there.
The patterning mechanism depends on the patterning rings to which there occurs the radial attachment of the yarns. These rings have to get rotated to provide the needed shogging action, which is one of the most crucial mechanisms occurring in the warp-knitting machine. This motion limits the patterning capability of the circular knitting machines. But it allows the easy threading of the rings and also makes the threaded rings to rotate about their centre in the smallest possible space. Originally the knitting machines based on the novel conical needle-bed concept and patterning rings used to contain a mechanical system designed to validate the proposed model. This cam-based mechanism was considered to be profitable in terms of cost. But its major disadvantage was that it lacks flexibility. For knitting different types of the fabric structure, we need a separate cam profile.
A machine model displaying truncated-cone needle-bed and patterning rings This automated system transforms the motion produced by the cam into the rotation of the patterning rings through the mechanical linkage. The arrangement and length of the linkage components depend on the dimensions of the machine elements and available physical space. The first model of the circular knitting machine employed a 72-needle truncated-cone. In this device, there occurred a ring rotation of about 80o that was equivalent to 16 needle spaces. At that time this no. of
rotations was considered sufficient for creating most of the knit structures. The significant advancements done in these machines included the use of enclosed cam followers in the patterning cams. It helped to reduce the shocks and vibrations that used to occur with the open face cams. There also occurred enhancement in the performance of cam brought by the utilization of cyclonical profiles for every rise and fall segment. These improvements served to obtain the best results for high-speed applications. The tricked truncated cone concept of the circular knitting machine connects the vertical reciprocating and radial swinging motions in one simultaneous action of the needles. There also occurs the shogging movement of the patterning rings in these devices, thus making them incomparable. These models got successfully created according to the industrial standards by the pre-eminent circular knitting machine manufacturer in India. These have also been tested and trialled by the industrialists. The mechatronic solution to the decreased flexibility offered by the truncated cone needle-bed circular knitting machines: As mentioned earlier, the truncated cone needle-bed concept of circular knitting machine offers reduced flexibility. Whenever a manufacturer has to knit
different fabric structure, he has to change the cam profile. The flexibility of the patterning depends on how comfortably you can modify the length of the pattern chain and the motion produced by the shogging mechanism. But, in the cam-driven machines, change of pattern needs changing the patterning cam. For solving this problem, a much more flexible and innovative mechatronic solution came into existence. It was to rotate the patterning rings by employing the servomotors directly. For satisfying the requirements of the knitting procedure, i.e. speed of reaction and position control, we selected servomotors over the stepper motors. Additionally, the servomotor controllers can store the programs of the series of the movements that used to occur for a given fabric pattern. For carrying out the patterning mechanism, we need speedy responses and precise position control. Only AC brushless servomotors can satisfy these requirements. These work at a high machine speed of about 1000 rpm to rotate the three patterning rings. In the second prototype of the circular knitting machine, rings used to hang via belt and pulley arrangement. Therefore, the employment of servomotors also reduces the no. of components used in the device. It further helps to
decrease the mechanical vibrations linked with the cam-driven mechanism. The circular knitting machine manufacturer in India then devised, built and tested the servomotor concept for the patterning mechanism. It consists of three rings each controlled by the motors connected to the load via belts and pulleys. This arrangement ensures an appropriate gear ratio and is also not limited by the mechanical properties of the linkages as used to occur in the automated design.
For testing the very fast response of the system, the manufacturers checked the mechanism without yarns.
On examination, it displayed the maximum rotation of 80° in alternating directions in the specified time of 20 min. Accelerating from zero to 139 rpm in first 10 min. and decelerating to zero again in the other 10min., the device showed that it could deliver speedy responses. This mechatronic solution also enables the creation of those knitting patterns that the manufacturers couldn't produce earlier due to the reduced size of the memory of the hardware used. It allows hundreds of machines cycles rather than that of the limited numbers that used to occur in a cam mechanism. Though the concept of servomotor can prove a bit costly but the patterning flexibility and the design simplicity that it renders makes it the best solution concept. Contact us: We at Bharat Machinery Works supplies premium quality and high-output yielding circular knitting machines. Being a leading circular knitting machine manufacturer in India, we always take care to utilize fine grade components for our devices. Our technicians have strict guidelines for checking all the knitting machines on several parameters before handing them over to the clients. We not only ensure the timely delivery of the machines but also offer excellent aftersale services.
If you are looking for high-quality knitting machines, contact us. We ensure to deliver you the best as per your requirements.