introduction
Corrugated resistors use a ceramic tube as a frame, with corrugated alloy resistance wire evenly and vertically wound around it. These resistors offer advantages such as good heat dissipation, high power output, overload resistance, and high voltage tolerance. Furthermore, they operate without noise, interference, or harmful magnetic fields. They are widely used in electrical circuits such as elevators, rolling mills, cranes, wire drawing machines, load testing inverters, brakes, servo systems, and power supplies.
In the traditional winding process, we first press the corrugated resistance wire to the required specifications on a simple corrugating machine. Then, on another winding machine, one person holds the corrugated resistance wire to control the tension, while another person manually cranks a handwheel to wind the pressed corrugated resistance wire vertically onto the ceramic frame according to the set pitch. However, manual winding is costly, inefficient, and the pass rate heavily depends on the operator's skill level, with human error and uncertainties accounting for a significant portion of the results. Therefore, the market urgently needs an automated machine that integrates corrugation pressing, winding, and wire arrangement.
principle
In a corrugated wire winding machine, the matching relationship between the corrugating speed, winding speed, and wire laying speed directly affects the winding effect of the corrugated resistor. If the corrugating speed is too fast, the corrugated resistor wire cannot be wound in time, resulting in ineffective winding. If the corrugating speed is too slow, the corrugated resistor wire will be stretched and deformed due to the tension of the rotating frame, directly affecting the resistor value. The wire laying mechanism must wind evenly according to the set pitch and frame winding speed. If the wire laying speed is too slow, it will cause wire overlap, leading to a short circuit. If the wire laying speed is too fast, the wire pitch will be too large, making it impossible to guarantee the resistor value. Therefore, the three factors must be effectively matched. Thus, the matching of the corrugating speed, winding speed, and wire laying speed is crucial. Only when the matching relationship of the three factors is controlled within an appropriate range can a qualified product be wound.
In the corrugated winding machine, we first need to calculate the current bobbin winding speed by using the encoder and PLC interrupt sampling. Then, based on the bobbin winding speed, we can calculate the speed of the corrugated motor and the speed of the wire laying motor.
Winding machine speed sampling
The encoder sampling is selected in A/B phase quadrature counting mode, the encoder line count is p, the sampling time is Δt (in ms), the value before interruption is a1, and the value after interruption is a2. The winding machine winding speed is v1 (in r/min).
The winding speed of the winding machine
Cable speed calculation
To ensure the pressed corrugated resistance wire is evenly wound on the frame, the wire guide travels one pitch for every one revolution of the frame. The wire guide speed is v2, the wire guide pitch is p (in mm), and the lead screw lead is m (in mm). Therefore...
The speed of the ribbon motor can be obtained
Calculation of ripple velocity
To ensure the pressed corrugated resistance wire is wound onto the frame in a timely manner, their speeds need to be matched. The frame diameter is d1, the corrugating gear diameter is d2, the corrugated resistance wire width is d, and the corrugating gear speed is v3 (in r/min). Since their linear velocities are the same, therefore...
The speed of the corrugated gear can be obtained
Fine-tuning of ripple speed
According to formula ⑤, the rotational speed of the pressure-corrugated gear can be calculated, but in actual practice, due to...
The ratio is not necessarily an integer; rounding will cause a slight deviation between the corrugation speed and the spindle winding speed. Therefore, we generally use as the actual corrugation speed, i.e., the fine-tuning amount.
Electronic control hardware configuration
The main controlled objects of this system are the corrugated motor, winding motor, and cable-laying motor. It needs to perform start, stop, and jog functions for the main shaft winding motor, left and right movement and jog control for the cable-laying mechanism, and jog function for the corrugated motor. It also needs to perform potentiometer speed adjustment, speed sampling, turns counting, and high-speed output functions. Therefore, the system requires the PLC to have analog inputs, analog outputs, a high-speed counting port, a high-speed pulse output port, and a certain number of I/O points. After comprehensive comparison, the Siemens S7-224XPCN PLC was selected, and the HITECH PWS6600T-P was selected for the human-machine interface (HMI) for setting and displaying various parameters. The servo system uses the Teco TSTA20C servo driver and the TSB08751C servo motor.
Figure 1 Motor control diagram
In Figure 1, M1 is the main spindle winding motor, M2 is the ribbon cable motor, M3 is the corrugated motor, A1~A3 are servo drivers, and G is the switching power supply.
Figure 2 PLC schematic diagram
Because the Siemens S7-224XPCN only has two high-speed output ports, the spindle winding motor uses speed mode control. The winding speed is controlled by the servo driver via the speed mode control through the analog input port calculated by the PLC and then output through the analog input port, adjusting the speed via a potentiometer. The encoder signal is then sampled through PLC input ports I1.2 and I1.3, and the PLC calculates and controls the pulse frequency of the cable laying motor and the corrugated press motor in position mode.
In Figure 2, A4 is the PLC, A5 is the touch screen, Q0.0 and Q0.1 are used to control the pulse frequency of the ribbon motor and the corrugated motor, respectively, and Q0.2, Q0.3 and Q1.0 are used to control the direction of the ribbon motor, the corrugated motor and the wound motor, respectively.
Software programming
The PLC we selected is a Siemens XP224CN. The encoder sampling is set to A/B phase quadrature counting, and the high-speed counting mode is HSC2, so the pulse count is HC2. The interrupt event number is 10.
Figure 3 Frequency calculation for cable motors and corrugated motors
Figure 4 shows the pulse output of the cable motor and the corrugated motor.
The spindle winding motor frequency is VD200, the corrugated wire pressing motor frequency is VD204, the cable laying motor frequency is VD208, and the corrugated wire pressing motor frequency is VD208. For ease of calculation, assume the PLC sends 1000 pulses, the cable laying mechanism travels 1mm, and the corrugated resistance wire is pressed 1mm. The frame diameter is VD100, the corrugated gear diameter is VD104, the corrugated resistance wire width is VD108, and the cable laying pitch is VD112 (*.***).
Conclusion
The spindle winding speed is obtained by encoder interrupt sampling, and then the frequency of the wiring motor and corrugated motor is calculated by the PLC. This allows for precise control of the wiring and corrugated servo motors, achieving real-time three-axis matching. This fully leverages the high processing speed and flexibility of the PLC. The equipment is simple to operate and easy to master, with high reliability, significantly improving production efficiency and saving labor and manufacturing costs. Users have generally given positive feedback after using it.
References
[1] Siemens S7-200 Programming Manual
[2] Quan Yi Electronics Co., Ltd., HITECHADP6 Software User Manual
[3] Teco Electronics Co., Ltd., Teco TSTA Series Product Manual
[4] Teco Electronics Co., Ltd., Teco Drive User Manual
[5] Taiwan Mingwei Technology Co., Ltd., Switching Power Supply Selection Manual
