Adjustment requirements and specifications for the belts of circular knitting machines

The adjustment requirements and standards for the belt of the large circular knitting machine: As the core equipment for the production of knitted fabrics, the belt of the large circular knitting machine, as a key component for power transmission and mechanism linkage, its adjustment accuracy directly affects the stability of equipment operation, the quality of fabric weaving and the service life of the belt. To ensure the efficient, low-consumption and stable operation of the equipment and avoid problems such as yarn breakage, uneven stitches and abnormal equipment noise caused by improper belt adjustment, the following belt adjustment requirements are formulated in light of the operational characteristics and production reality of the large circular knitting machine, which are applicable to the daily adjustment and maintenance of belts for all types of large circular knitting machines (including single-sided and double-sided large circular knitting machines). I. Preparation Requirements before Adjustment 1. Equipment status Confirmation: Before adjustment, the main power supply of the equipment must be turned off. The operation should be carried out only after the equipment has completely stopped and the transmission components have cooled down. It is strictly prohibited to operate while the equipment is in operation to prevent mechanical damage. At the same time, clean the cotton fluff, oil stains, dust and other debris on the surface of the belt and pulley to avoid the debris affecting the adjustment accuracy and the belt transmission effect. 2. Preparation of tools and consumables: Prepare special tools such as torque wrenches, tensioners, vernier calipers, and screwdrivers, as well as belt cleaners and anti-slip agents (as needed); Check the appearance of the belt in advance, remove those with cracks, aging, tensile deformation or edge wear, and ensure that the adjusted object is a qualified belt. 3. Personnel qualification requirements: Operators must be familiar with the transmission structure, belt model and adjustment principle of the circular knitting machine. They can only take up their posts after passing professional training. Unlicensed personnel are strictly prohibited from making adjustments without authorization to avoid damaging the equipment or affecting production due to improper operation. Ii. Core Adjustment Requirements (1) Belt Tension Adjustment (Key Requirements) The belt tension is the core of the adjustment. If it is too loose, it will cause the belt to slip and lose rotation, resulting in unstable weaving speed and uneven stitch density. Excessive tightness will accelerate belt wear, increase bearing load, and shorten the service life of the belt and equipment components. The specific requirements are as follows: 1. Tension standard: Press the middle of the belt (the midpoint between the two pulleys) with your fingers. When the pressing force is 20-30N, the sinking of the belt should be controlled at 5-8mm (for different models of large round machines, the sinking can be slightly adjusted according to the width of the belt. When the width is ≥50mm, the sinking can be relaxed to 6-10mm). When using a torque wrench for detection, the belt tensioning torque must comply with the requirements of the equipment manual, usually ranging from 15 to 25N·m. 2. Adjustment operation: Fine-tune the belt through the tensioning wheel adjustment bolt provided by the equipment. Rotate the bolt clockwise to tighten the belt and counterclockwise to loosen it. When making adjustments, it is necessary to operate step by step. Pause after each adjustment and check the tension to avoid excessive tension due to a large adjustment range at one time. 3. Synchronization requirements: When adjusting multiple parallel belts (such as the main drive belt and the yarn feeding mechanism belt), it is necessary to ensure that the tension of each belt is consistent, with a deviation not exceeding 1mm, to prevent premature aging or breakage due to uneven force on individual belts. The alignment adjustment of two pulleys: The parallelism and coaxiality deviation of the pulleys can cause the belt to deviate, the edge to wear, and even fall off. The adjustment requirements are as follows: 1. Parallelism adjustment: Take the driving pulley as the reference and use a vernier caliper to measure the height difference at both ends of the driven pulley. The deviation should be ≤0.5mm to ensure that the surfaces of the two pulleys are in the same plane and there is no inclination. If there is any deviation, it should be corrected by adjusting the position of the installation bracket of the driven pulley. 2. Coaxiality adjustment: Detect the axial deviation between the driving pulley and the driven pulley. The radial deviation should be ≤0.3mm and the axial deviation ≤0.2mm to prevent lateral tension during belt operation. After adjustment, manually rotate the pulley to ensure smooth belt operation without any jamming or deviation. 3. Wheel surface cleaning: Before adjustment, it is necessary to inspect the pulley grooves, remove debris and burrs in the grooves, ensure that the surface of the grooves is smooth and closely adheres to the belt, and avoid uneven force on the belt due to uneven grooves. Belt running position adjustment 1. Belt deviation correction: Run the equipment no-load for 3 to 5 minutes and observe the belt running trajectory. If the belt deviates to one side, slightly adjust the lateral position of the tensioner pulley (tighten the deviated side appropriately and relax the other side) until the belt runs stably in the middle of the pulley without edge friction. 2. Belt length compatibility: When replacing a new belt, it is necessary to select a belt that matches the equipment model (the model, length, and width should comply with the equipment manual). It is strictly prohibited to use belts with a length deviation exceeding 2mm to avoid the tension not meeting the standard due to inappropriate length. Iii. Requirements for Inspection and Trial Operation after Adjustment 1. Static Inspection: After the adjustment is completed, manually rotate the pulley to check that the belt is not loose, deviated or jammed, and that the pulley and the belt are evenly attached without any gap. Pull the belt by hand to confirm that the tension meets the standard, without excessive looseness or tension. 2. Dynamic trial run: Connect the power supply and run the equipment no-load for 10 to 15 minutes. Observe the running status of the belt. There should be no abnormal noise, no deviation, and no slippage. Test the rotational speed of the equipment and the weaving accuracy to ensure that there are no abnormalities compared with before adjustment, and no problems such as broken yarns or stitch defects. 3. Load test run: After passing the no-load test, conduct a load test run (at normal production speed and normal yarn feeding rate). After running for 30 minutes, recheck the belt tension and pulley temperature (temperature ≤60℃). If there is no abnormal wear or overheating, it is considered to be adjusted as qualified. Iv. Requirements for Daily Maintenance and Adjustment Frequency 1. Daily Inspection: Before starting the machine every day, check the appearance and tension of the belt. If any problems such as cracking, wear, or slippage are found, make timely adjustments or replacements. After the daily production is completed, clean the debris on the surface of the belt and pulley to prevent oil stains from eroding them. 2. Regular adjustment: Recheck and adjust the belt tension and pulley alignment once a week. Conduct a comprehensive adjustment once a month, with a focus on correcting the parallelism and coaxiality of the pulleys to ensure the long-term stable operation of the equipment. 3. Seasonal adaptation adjustment: In the high-temperature environment of summer, the belt is prone to loosening, and the tension should be appropriately reduced (the subsidence amount should be decreased by 1-2mm). In the low-temperature environment of winter, the flexibility of the belt decreases. The tension can be appropriately relaxed (by increasing the subsidence by 1mm) to prevent the belt from becoming brittle and breaking due to low temperature. V. Precautions 1. During the adjustment process, it is strictly forbidden to forcefully pry the pulley or belt to avoid damaging the pulley bearings and the belt body. 2. If the belt shows signs of aging, cracking, stretching deformation, etc., it should be replaced in time. Do not make up for it by over-tightening, otherwise it will damage the transmission mechanism of the equipment. 3. After adjustment, records should be kept, with detailed information such as the adjustment date, adjustment part, tension parameter, and operator filled in to facilitate subsequent traceability and maintenance. When the equipment is out of service for a long time (more than one month), the tension of the belt should be relaxed to prevent it from aging and deforming due to being in a taut state for a long time. By following the above adjustment requirements, the operational stability of the circular knitting machine can be effectively enhanced, the frequency of belt failures can be reduced, the quality of knitted fabric production can be guaranteed, the service life of the equipment and belts can be prolonged, production costs can be lowered, and the efficient production needs of various knitted fabrics can be met.