Abstract: Based on a brief introduction to the working principle of the covering yarn machine, this paper focuses on the design of an automated system for a servo-driven forming covering yarn machine. The system is based on an integrated control structure of PLC control platform, touch screen, frequency converter, and servo drive. Keywords: Covering yarn machine, servo forming, servo drive, PLC, frequency converter , cross angle, anti-hard edge, anti-overlapping, anti-drop-off, oil bath gearbox 1. Introduction The covering yarn machine can be used to produce various specifications of spandex covered yarn. The core yarn is made of spandex and covered with nylon, polyester, and other chemical fiber elastic yarns, filaments, or even silk, cotton yarn, wool yarn, and various blended yarns. These elastic covered yarns or yarns are widely used in elastic stockings, sports stockings, pantyhose, knitted underwear, woven fabrics, elastic clothing, sportswear, casual wear, sweaters, elastic bands, etc. The covering yarn machine can produce single-covered yarn, double-covered yarn, and some special twisted yarns and threads, producing some high value-added products. The traditional covering yarn machine (hereinafter referred to as the mechanical forming covering yarn machine) consists of: an 18.5KW VFD-B frequency converter driving two 9KW asynchronous motors to drive the main shaft, which in turn drives the spindle to rotate at high speed and wind through mechanical gear ratios. A mechanical oil bath gearbox drives the traversing mechanism to move back and forth, achieving the winding and forming function. A speed monitoring instrument monitors the operating speed of the spindle and winding at all times. The main technical parameters of the mechanical forming covering yarn machine are: Disadvantages: 1. Speed ​​can only be adjusted through the frequency converter panel, which is not user-friendly. 2. Because the forming mechanism is a mechanical oil bath gearbox, the overall machine speed is limited to no more than 40 meters per minute. 3. Due to the mechanical oil bath gearbox, the winding process suffers from resistance effects such as overlapping and hard edge protrusions (which are very detrimental to the next unwinding process, limiting the yarn thickness to 3 cm). 4. Because the forming mechanism is a mechanical oil bath gearbox, mechanical wear after long-term operation makes fundamental repair, maintenance, and adjustment difficult. 2. Automation Design of Electronic Forming Covering Machine Due to the limitations of traditional mechanical forming, such as speed, forming effect, and maintenance difficulties, the development of covering machines in the market has been severely restricted. Therefore, in recent years, many textile machinery manufacturers and automation system design and integration companies have been focusing on developing electronic forming covering machines. However, due to difficulties in forming control precision, anti-overlapping algorithms, anti-resistance effects, anti-drop-off, mechanical precision, winding forming cross-angle algorithms, and production debugging cycles (20-80 hours per spindle), progress has been limited. Through more than a month of recent efforts, we have designed a control scheme in China that uses Delta EH series programmable process controllers as the main control unit to control the speed of the entire machine's spindles (Delta frequency converter control), the speed of the winding motor (Delta frequency converter series control), and the electronic forming of the traverse yarn transfer (Delta servo drive). Process parameters are set and displayed using a Delta human-machine interface. The mechanical oil bath gearbox has been eliminated. The spindle speed signal is measured using a high-speed speed meter, and the winding roller speed is also measured. Process parameters such as spindle speed, traverse speed, forming angle, working time, twist, etc., can be set on the human-machine interface (HMI). Fault information occurring during operation is also displayed on the HMI, facilitating troubleshooting. The main component list is as follows: PLC: DVP-EH (high-speed pulse output up to 200KHz, high-speed counting channels 200KHz/channel, four channels in total) HMI: DOP-AS (5.7-inch) Inverter: VFD-B (18.5KW) Servo Driver: VSD-B (0.75KW, encoder resolution: 10000, position positioning time: 2ms) Advantages: 1. The machine speed, traverse speed, forming parameters, etc., can be freely changed via the touchscreen to meet different production needs; the interface is user-friendly and convenient. 2. Because the forming traverse mechanism uses servo drive, the overall machine speed can be increased to 100 meters/minute, greatly improving production efficiency, which is 200%-300% faster than the original mechanical forming machine. 3. Because the forming traverse mechanism uses servo drive, the winding forming process solves problems such as overlapping and hard edge protrusion resistance effects, allowing for winding spindles up to 10 cm thick, 300%-400% faster than the original mechanical forming machine, saving spindle changeover time and improving production efficiency. 4. Because the forming mechanism uses servo drive, the mechanical structure is simple, making maintenance and adjustments convenient even after long-term operation. The main technical parameters of the electronic forming covered yarn machine are: 3. Introduction to the implementation of servo electronic forming: 1) Winding speed setting: The winding speed, i.e., the main machine speed, determines the overall machine production speed. The inverter operating frequency is set according to the winding speed; the winding speed determines the winding linear speed. 2) Lateral Movement Speed ​​Setting: The lateral movement speed, also known as the transverse yarn movement speed, is determined by the ratio between the lateral movement speed and the winding speed, based on the winding requirements of different yarn types. The crossover angle between the two windings is determined accordingly. The lateral movement speed should not be too slow or too fast. Too slow a speed will cause excessive accumulation of yarn edge during the reverse lateral movement, leading to hardening and yarn breakage. Too fast a speed will cause overshoot and jitter during the reverse servo movement, also resulting in yarn breakage. 3) Initial Stroke Setting: The initial stroke represents the distance between A and B. 4) Initial Roll Diameter Setting: The initial roll diameter setting must be accurate; otherwise, it will affect the forming effect. 5) Stop Delay Setting: The stop delay means that after pressing the stop button, the turntable cannot stop immediately due to inertia. Therefore, the lateral movement mechanism must be delayed for a period of time until the turntable completely stops before stopping the lateral movement. Otherwise, the yarn will be heavily wound at the lateral movement stop position. 6) Differential Distance: AC and DB are the differential winding lengths. During the AB reciprocating motion, the actual reciprocating stroke is not always from point A to point B, or from point B to point A. It's actually a cycle from point A to point D, point D to point C, point C to point B, and then back to point B. This is mainly to address the phenomenon of bulges on both sides during winding (commonly known as the resistance effect). 7) Forming Angle Adjustment Parameter: The forming angle adjustment parameter determines the slope of the yarn spindle's edge during winding. Since the forming angle is determined by the winding speed, traverse speed, and yarn thickness, it can be corrected through the forming angle adjustment parameter to achieve a more aesthetically pleasing effect. A larger parameter indicates a steeper slope, and a smaller parameter indicates a flatter slope. 8) Soft Edge Adjustment Parameter Setting: Due to the need for unwinding during winding, the spindle edge needs to be relatively soft to avoid breakage during unwinding caused by a too-hard or too-tight edge. Adjusting the soft edge parameter effectively adjusts the softness of the edge. A larger parameter results in a harder edge, and a smaller parameter results in a softer edge. 4. Conclusion Over the course of August and September, we conducted winding tests using different yarns (40D-200D specifications). The current winding effect is very close to that of Manigate, a leading international manufacturer of covering yarn machines. With the increasing efficiency, maturity, and cost-effectiveness of servo winding, automated covering yarn machines using servo winding will gradually replace all traditional mechanical covering yarn machines in the textile industry. They offer significantly higher efficiency, larger package capacity, and improved quality. High-quality spindles maintain long-term stability at high speeds. The two-stage transmission mechanism ensures more rational force distribution and a wider range of applications. The elimination of the oil bath gearbox makes maintenance easier, resulting in better winding and easier unwinding of soft edges. The maturity of servo winding technology will completely replace traditional mechanical winding technology. All currently mechanically wound spinning machines will experience revolutionary breakthroughs (including covering yarn machines, doubling machines, and winding machines), propelling the domestic textile machinery industry from inefficiency and the low-end market to a new era of high efficiency and high quality.