Constant tension control method of microwire pay-off device

Abstract

According to the constant tension control method of the microwire pay-off device, the pay-off device comprises an upper computer, a controller, a servo driver, a pay-off rack, a pay-off mechanism and a guide wheel type tension sensor. The paying-off mechanism comprises a paying-off shaft connected to the paying-off frame through a bearing, a paying-off disc connected to the paying-off shaft and a servo motor arranged on the paying-off frame and in driving connection with the paying-off shaft, the tension of a wire rod is collected in real time through a guide wheel type tension sensor, the controller adjusts the rotating speed of the servo motor on line through a PID algorithm, the steady-state error of the tension is smaller than or equal to + / -0.02 N, and then the tension is controlled to be in a stable state. The response time is less than or equal to 0.3 s, the problems of large tension fluctuation and slow response of a traditional counterweight type are thoroughly solved, the mechanical counterweight and the working noise are reduced, the device can be networked with an upper computer, the centralized control of the whole wire is realized, and the device can be widely applied to superfine wire precision twisting and wrapping production lines.

Description

Technical Field

[0001] This invention relates to the field of wire feeder technology, and more particularly to a constant tension control method for a micro-wire feeder. Background Technology

[0002] A wire feeder is an auxiliary device for wires and cables that is used in conjunction with a stranding machine or winding machine to feed wires and cables.

[0003] Existing micro-wire feeders mostly use mechanical counterweights or friction plates to provide tension, which has the following drawbacks:

[0004] 1. Tension fluctuates with the radius of the coil and cannot be truly constant;

[0005] 2. Mechanical switches can only achieve start and stop control, and the response is lagging, which can easily cause the wire to become thin or the strands to jump;

[0006] 3. No real-time tension data, unable to link with the backend host.

[0007] Therefore, there is an urgent need for a tension closed-loop control scheme that can adjust the tension in real time, has small tension fluctuations, and a fast response. Summary of the Invention

[0008] The problem to be solved by the present invention is to provide a constant tension control method for a micro-wire feeder, which can adjust the tension in real time, reduce tension fluctuations, and improve response speed.

[0009] To solve the above technical problems, a constant tension control method for a micro-wire feeder provided by this invention is adopted, comprising the following steps:

[0010] S1. Preparation of the wire feeder: The wire feeder includes a host computer, controller, servo driver, wire feed frame, wire feed mechanism, and guide wheel tension sensor. The wire feed mechanism includes a wire feed shaft connected to the wire feed frame via bearings, a wire feed reel connected to the wire feed shaft, and a servo motor mounted on the wire feed frame and driven by the wire feed shaft. The guide wheel tension sensor is mounted on the wire feed frame. The controller is electrically connected to the servo driver and the guide wheel tension sensor. The servo driver is electrically connected to the servo motor. The controller is communicatively connected to the host computer.

[0011] S2. Set the target tension value F0 on the controller;

[0012] S3. Install the wire spool on the pay-off reel and lead the wire out by passing it around the guide wheel tension sensor. The wire is then paid off by driving the pay-off reel to rotate via a servo motor.

[0013] S4. The tension value F is collected in real time by the guide wheel type tension sensor and fed back to the controller;

[0014] S5. The controller compares the real-time collected tension value F with the target tension value F0 and obtains the tension deviation value ΔF = F - F0.

[0015] S6. The controller calculates the speed correction amount Δn of the servo motor based on the tension deviation value ΔF using a PID algorithm.

[0016] S7. The controller updates the current speed value n of the servo motor to n+Δn and sends it to the servo driver;

[0017] S8. Repeat steps S4-S7 to keep the tension value F within the range of F0±0.02N.

[0018] Preferably, the PID algorithm in step S6 is an incremental PID, Δu(k) = Kp·[e(k)-e(k-1)] + Ki·e(k) + Kd·[e(k)-2e(k-1)+e(k-2)], e(k)=F0-F(k), Kp=0.8-1.2, Ki=0.05-0.1, Kd=0-0.02.

[0019] Preferably, the controller uses an STM32F407 microcontroller.

[0020] Preferably, when |ΔF| is continuously greater than 0.5 N and exceeds 1 second, the controller alarms the host computer and stops the machine.

[0021] Preferably, the sampling frequency of the guide wheel type tension sensor is ≥1kHz and the accuracy is ±0.005 N.

[0022] Preferably, the encoder resolution of the servo motor is ≥17 bits and the speed loop bandwidth is ≥1 kHz.

[0023] Preferably, the controller uses MODBUS-RTU to communicate with the host computer.

[0024] Preferably, the host computer is an IPC industrial control computer.

[0025] The beneficial effects of this invention are as follows: This invention provides a constant tension control method for a micro-fine wire feeder. The tension of the wire is collected in real time by a guide wheel type tension sensor, and the controller adjusts the speed of the servo motor online using a PID algorithm, so that the steady-state tension error is ≤ ±0.02N and the response time is ≤0.3s. This completely solves the problems of large tension fluctuation and slow response of traditional counterweight type tension feeders, reduces mechanical counterweight and working noise, can be networked with a host computer to realize centralized control of the entire line, and can be widely used in precision stranding and wrapping production lines for ultra-fine wires. Attached Figure Description

[0026] Figure 1 A block diagram of the closed-loop control system of the present invention is illustrated.

[0027] Figure 2 The PID control flowchart of the present invention is illustrated.

[0028] Figure 3 The tension-time comparison experimental curve of the present invention is illustrated.

[0029] Figure 4 The servo motor speed-time response curve of the present invention is illustrated. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure.

[0031] Based on the embodiments described in this disclosure, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this disclosure.

[0032] refer to Figure 1-4 .

[0033] This invention provides a constant tension control method for a micro-wire feeder, comprising the following steps:

[0034] S1. Preparation of the wire feeder: The wire feeder includes a host computer, controller, servo driver, wire feed frame, wire feed mechanism, and guide wheel tension sensor. The wire feed mechanism includes a wire feed shaft connected to the wire feed frame via bearings, a wire feed reel connected to the wire feed shaft, and a servo motor mounted on the wire feed frame and driven by the wire feed shaft. The guide wheel tension sensor is mounted on the wire feed frame. The controller is electrically connected to the servo driver and the guide wheel tension sensor. The servo driver is electrically connected to the servo motor. The controller is communicatively connected to the host computer.

[0035] S2. Set the target tension value F0 on the controller;

[0036] S3. Install the wire spool on the pay-off reel and lead the wire out by passing it around the guide wheel tension sensor. The wire is then paid off by driving the pay-off reel to rotate via a servo motor.

[0037] S4. The tension value F is collected in real time by the guide wheel type tension sensor and fed back to the controller;

[0038] S5. The controller compares the real-time collected tension value F with the target tension value F0 and obtains the tension deviation value ΔF = F - F0.

[0039] S6. The controller calculates the speed correction amount Δn of the servo motor based on the tension deviation value ΔF using a PID algorithm.

[0040] S7. The controller updates the current speed value n of the servo motor to n+Δn and sends it to the servo driver;

[0041] S8. Repeat steps S4-S7 to keep the tension value F within the range of F0±0.02N.

[0042] Based on the above embodiments, the PID algorithm in step S6 is an incremental PID, Δu(k) = Kp·[e(k)-e(k-1)]+ Ki·e(k) + Kd·[e(k)-2e(k-1)+e(k-2)], e(k)=F0-F(k), Kp=0.8-1.2, Ki=0.05-0.1, Kd=0-0.02.

[0043] Based on the above embodiments, the controller uses an STM32F407 microcontroller.

[0044] Based on the above embodiments, when |ΔF| is continuously greater than 0.5 N and exceeds 1 second, the controller alarms the host computer and stops the machine.

[0045] Based on the above embodiments, the sampling frequency of the guide wheel tension sensor is ≥1kHz, and the accuracy is ±0.005 N.

[0046] Based on the above embodiments, the encoder resolution of the servo motor is ≥17 bits, and the speed loop bandwidth is ≥1 kHz.

[0047] Based on the above embodiments, the controller uses MODBUS-RTU to communicate with the host computer.

[0048] Based on the above embodiments, the host computer is an IPC industrial control computer.

[0049] Verification method:

[0050] Wire material: φ0.05mm silver-plated copper wire, target tension is 0.50N;

[0051] The outer diameter of the wire spool was reduced from 110mm to 90mm;

[0052] Record the tension curve over 30 minutes. Results:

[0053] - Steady-state error: ±0.015 N (3σ)

[0054] - Maximum overshoot: 0.03 N

[0055] - Response time (±5% error band): 0.28s

[0056] This achieved the goal of reducing the defect rate from 1.2‰ to 0.08‰.

[0057] Appendix Figure 3 This is the tension-time comparison experiment curve.

[0058] Experimental wire: φ0.05mm silver-plated copper wire, wire feeding speed 50m / min, spool outer diameter 110 mm→90 mm;

[0059] Sampling: Tension sensor 1kHz, curve moved averaged over 1s;

[0060] The error band of ±0.02N is a design requirement of this invention, and the curve must remain within the band throughout its entire length.

[0061] The key indicators are as follows:

[0062] Experimental curve for existing mechanical counterweight method: peak-to-peak value 0.30 N (0.35→0.64), 3σ=0.11 N;

[0063] Experimental curves for this closed-loop control method: peak-to-peak value 0.03 N (0.497→0.504), 3σ=0.015 N;

[0064] Volatility reduction rate: (0.30−0.03) / 0.30 = 90%.

[0065] Appendix Figure 4 The servo motor speed-time response curve is shown, with response metrics labeled:

[0066] - Rise time tr ≈ 0.12 s (10%→90%)

[0067] - Peak time tp ≈ 0.28 s

[0068] - Overshoot Mp ≈ 3.2%

[0069] - Settling time ts (±5%) ≈ 0.28 s

[0070] - Steady-state error ess = 0 rpm

[0071] 1. Experimental conditions: Unloaded coil, STM32F407 1 kHz interrupt PID, Kp=1.0, Ki=0.08, Kd=0.01.

[0072] 2. The actual rotational speed is fed back by the servo driver's 17-bit encoder, with a sampling period of 125 µs, and is sent to the controller after being averaged for 1 ms.

[0073] 3. The adjustment time of 0.28 s is much less than the process allowance of 0.5 s, which meets the requirement that the transient fluctuation of the tension of the micro-wire is ≤ ±0.02 N.

[0074] This invention uses a guide wheel type tension sensor to collect wire tension in real time, and the controller uses a PID algorithm to adjust the speed of the servo motor online, so that the steady-state tension error is ≤±0.02N and the response time is ≤0.3s. It completely solves the problems of large tension fluctuation and slow response of traditional counterweight type tension sensors, reduces mechanical counterweight and working noise, can be networked with a host computer to realize centralized control of the whole line, and can be widely used in precision stranding and wrapping production lines for ultra-fine wires.

[0075] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A constant tension control method for a micro-wire feeder, characterized in that, It includes the following steps: S1. Preparation of the wire feeder: The wire feeder includes a host computer, a controller, a servo driver, a wire feed frame, a wire feed mechanism, and a guide wheel tension sensor. The wire feed mechanism includes a wire feed shaft connected to the wire feed frame via bearings, a wire feed reel connected to the wire feed shaft, and a servo motor mounted on the wire feed frame and driven by the wire feed shaft. The guide wheel tension sensor is mounted on the wire feed frame. The controller is electrically connected to the servo driver and the guide wheel tension sensor. The servo driver is electrically connected to the servo motor. The controller is communicatively connected to the host computer. S2. Set the target tension value F0 on the controller; S3. Install the wire spool on the pay-off reel and lead the wire out by passing it around the guide wheel tension sensor. The wire is then paid off by driving the pay-off reel to rotate via a servo motor. S4. The tension value F is collected in real time by the guide wheel type tension sensor and fed back to the controller; S5. The controller compares the real-time collected tension value F with the target tension value F0 and obtains the tension deviation value ΔF = F - F0. S6. The controller calculates the speed correction amount Δn of the servo motor based on the tension deviation value ΔF using a PID algorithm; S7. The controller updates the current speed value n of the servo motor to n+Δn and sends it to the servo driver; S8. Repeat steps S4-S7 to keep the tension value F within the range of F0±0.02N.

2. The constant tension control method for a micro-wire feeder according to claim 1, characterized in that, The PID algorithm described in step S6 is an incremental PID, Δu(k) = Kp·[e(k)-e(k-1)] + Ki·e(k) + Kd·[e(k)-2e(k-1)+e(k-2)], e(k)=F0-F(k), Kp=0.8-1.2, Ki=0.05-0.1, Kd=0-0.

02.

3. The constant tension control method for a micro-wire feeder according to claim 2, characterized in that, The controller uses an STM32F407 microcontroller.

4. The constant tension control method for a micro-wire feeder according to claim 3, characterized in that, When |ΔF| is continuously greater than 0.5 N for more than 1 second, the controller sends an alarm to the host computer and stops the machine.

5. The constant tension control method for a micro-wire feeder according to claim 1, characterized in that, The guide wheel type tension sensor has a sampling frequency of ≥1kHz and an accuracy of ±0.005 N.

6. The constant tension control method for a micro-wire feeder according to claim 1, characterized in that, The encoder resolution of the servo motor is ≥17 bits, and the speed loop bandwidth is ≥1 kHz.

7. The constant tension control method for a micro-wire feeder according to claim 1, characterized in that, The controller communicates with the host computer using MODBUS-RTU.

8. The constant tension control method for a micro-wire feeder according to claim 1, characterized in that, The host computer is an IPC industrial control computer.

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