Circular Knitting Machine: Causes and Elimination of Stoppage Marks

Circular knitting machines commonly leave streaks in the weft direction of the fabric after stopping, and the characteristics of these streaks vary based on factors such as fabric type and machine conditions. Generally, a fine indentation appears, distinctively marking the boundary between the fabric woven before and after machine stoppage. In some cases, wider streaks may occur, and the differentiation between the fabric before and after stopping is less pronounced. These streaks can lead to color variations in dyed fabric, causing challenges in fabric cutting and resulting in wastage if the issue is frequent and severe.

Causes of Streaks after Machine Stops:

There are several reasons for the occurrence of streaks:

1. Sudden changes in yarn delivery can result in uneven yarn tension, altering the coil's shape and size, causing streaks.
2. Wear between the drive gear and the main spindle due to relative oscillations during yarn delivery can lead to gear positioning groove and shaft wear. This wear affects yarn tension, resulting in streaks.
3. Relative sliding between the yarn delivery adjustment disc and the drive belt due to wear or insufficient pressure can cause friction coefficient changes, impacting yarn tension and creating streaks.
4. Wear or clogging of the drive teeth in the yarn carrier, wear of the drive belt, or increased relative sliding during machine stoppage and startup can alter yarn delivery per unit coil, causing streaks.
5. Loose or worn drive belts in other related parts of the yarn delivery system can lead to uneven tension during machine stoppage and startup, forming streaks.

Methods for Improving Streaks:

To improve streaks, several methods can be implemented:

1. Extend the deceleration time of the knitting machine to minimize the oscillation rate between gears and the relative sliding rate of the drive belt, reducing the abrupt change in yarn tension.
2. Increase the warp tension to stabilize yarn tension during machine stoppage and startup.
3. Reduce the virtual position of the lifting rod of the triangle seat chassis to minimize relative oscillation between gears and shafts, as well as reduce the virtual position between the needle bed and the triangle.
4. Choose machine models with wear-resistant components, avoiding designs that use steel wire runways and wave beads to minimize wear-related issues.
5. Control the lifting amount of the triangle seat chassis to prevent excessive drift during high-speed rotation, keeping the displacement within acceptable limits.

In summary, addressing the root causes of streaks and implementing these improvement methods can contribute to minimizing or eliminating streaks after a circular knitting machine stops.