CN-121680095-B - Spring forming on-line control system and control method

CN121680095BCN 121680095 BCN121680095 BCN 121680095BCN-121680095-B

Abstract

The invention relates to the technical field of precision spring manufacturing and automatic control, in particular to an online spring forming control system and a control method; the system comprises a dynamic modeling, disturbance observation, impedance decoupling and track correction module, calculates disturbance torque by constructing a mechanical transmission dynamic reference model and collecting servo parameters, and has the core that material deformation impedance components representing transient rheological characteristics of wires are decoupled from the disturbance torque, a position correction instruction is generated based on an elastoplastic compensation model, and a forming track is dynamically adjusted in a current period.

Inventors

SHAO NAIXIANG
FENG HUAJIAN

Assignees

杭州通用弹簧有限公司

Dates

Publication Date: 20260512
Application Date: 20260210

Claims (8)

1. A spring forming on-line control method is characterized by comprising the steps of constructing a mechanical transmission dynamics reference model, acquiring servo motor operation parameters in real time, wherein the mechanical transmission dynamics reference model is used for describing ideal dynamics of forming equipment in an idle state, calculating disturbance torque by using a disturbance observer, wherein the disturbance torque is a difference value between an actual output torque obtained by converting an actual current value and a theoretical reference torque output by the mechanical transmission dynamics reference model, decoupling a material deformation impedance component from the disturbance torque, wherein the material deformation impedance component represents transient rheological characteristics of a wire in a forming process, acquiring a preset elastoplasticity compensation model, generating a position correction instruction in real time based on the material deformation impedance component and the elastoplasticity compensation model, and superposing the position correction instruction into a target position instruction of a forming shaft to dynamically adjust a forming track in a current forming period; The method for decoupling the material deformation impedance component from the disturbance torque comprises the steps of constructing a band-pass filter, inputting the disturbance torque into the band-pass filter, filtering a low-frequency component caused by mechanical drift and a high-frequency component caused by electromagnetic interference, obtaining a cleaned torque signal, calculating the product of the cleaned torque signal and an actual speed value, and performing time integration on the product to obtain instantaneous forming energy density, marking the instantaneous forming energy density as a material deformation impedance component, wherein the numerical value of the material deformation impedance component and the tensile strength of the wire are in positive correlation; The method for superposing the position correction command to the target position command of the forming shaft comprises the steps of obtaining an original motion command of a current interpolation period, judging whether a deformation impedance component of a material exceeds a preset dead zone threshold, directly accumulating the position correction command to the tail end position of the original motion command if the deformation impedance component of the material exceeds the dead zone threshold, keeping the original motion command unchanged if the deformation impedance component of the material does not exceed the dead zone threshold, and adjusting a speed feedforward gain and a moment feedforward gain of the forming shaft according to the position correction command by utilizing a feedforward control strategy so as to eliminate dynamic lag caused by position correction.
2. The on-line control method for forming the spring according to claim 1, wherein the method for constructing the mechanical transmission dynamics reference model is characterized by comprising the steps of driving forming equipment to perform no-load operation test at a full speed section to obtain no-load test data, extracting friction characteristics and inertia characteristics of a mechanical transmission chain based on the no-load test data, establishing a dynamics equation comprising coulomb friction, viscous friction and moment of inertia by utilizing the friction characteristics and the inertia characteristics, and marking the dynamics equation as the mechanical transmission dynamics reference model, wherein calculation logic of theoretical reference torque is that an actual speed value and an actual acceleration value are input into the mechanical transmission dynamics reference model, and a moment component for overcoming self resistance of a mechanical system is calculated.
3. The spring forming on-line control method according to claim 1, wherein the method for calculating the disturbance torque by using the disturbance observer comprises the steps of multiplying an actual current value by a preset motor torque constant to obtain an actual output torque, uniformly expressing the actual output torque by subsequent calculation, subtracting a theoretical reference torque from the actual output torque to obtain a preliminary disturbance signal, performing low-pass filtering processing on the preliminary disturbance signal to inhibit high-frequency quantization noise, and marking the processed signal as the disturbance torque, wherein the bandwidth frequency of the disturbance observer is set to be higher than a wire forming characteristic frequency and lower than a current loop sampling frequency.
4. The method for on-line control of spring forming according to claim 1, wherein the method for generating the position correction command in real time based on the material deformation resistance component and the elastoplastic compensation model comprises defining a sensing axis and a cooperative axis, wherein the sensing axis is a servo axis for detecting a change of the material deformation resistance component, the cooperative axis is a servo axis for performing geometric correction, searching a rebound compensation amount corresponding to the material deformation resistance component in the elastoplastic compensation model, converting the rebound compensation amount into a pulse increment of the cooperative axis and marking the pulse increment as the position correction command, wherein the cooperative axis is configured as a diameter-variable axis or a pitch axis when the sensing axis is a wire feeding axis, and the cooperative axis is configured as a pitch axis when the sensing axis is the diameter-variable axis, and the generation and the execution of the position correction command are completed in the same interpolation period.
5. The method for on-line control of spring forming according to claim 4 is characterized by comprising the steps of obtaining a plurality of groups of sample wires with different physical properties, recording material deformation impedance components of each group of sample wires under standard forming instructions and geometric dimension deviation after forming, respectively, taking the material deformation impedance components corresponding to each group of sample wires as input characteristics, taking the corresponding geometric dimension deviation as output labels, constructing a mapping database, fitting a data relation in the mapping database by using a nonlinear regression algorithm, generating a compensation function, marking the compensation function as an elastoplastic compensation model, wherein the elastoplastic compensation model is used for describing nonlinear mapping relation between wire hardness fluctuation and required geometric correction.
6. The on-line control method for forming the spring according to claim 1 is characterized by further comprising the steps of monitoring spectral features of disturbance torque in real time, generating a cutter abrasion early warning signal if the amplitude of a specific frequency band in the spectral features is in a monotonic increasing trend along with time, generating a raw material batch change prompt signal if the average value of the disturbance torque is in a step change, and sending the cutter abrasion early warning signal and the raw material batch change prompt signal to a man-machine interaction interface.
7. An on-line control system for forming springs is used for realizing the on-line control method for forming springs according to any one of claims 1-6 and is characterized by comprising a model construction module, a data acquisition module, a disturbance observation module, a compensation calculation module and a motion control module, wherein the model construction module is used for constructing a mechanical transmission dynamics reference model and extracting friction characteristics and inertia characteristics of a mechanical transmission chain, the data acquisition module is used for acquiring servo motor operation parameters in real time, the parameters comprise current, position and speed information, the disturbance observation module is used for calculating disturbance torque by using a disturbance observer and decoupling material deformation impedance components from the disturbance torque, the compensation calculation module is used for acquiring a preset elastoplasticity compensation model and calculating position correction instructions based on the material deformation impedance components, and the motion control module is used for superposing the position correction instructions into target position instructions of a forming shaft and driving the servo motor to execute dynamic compensation.
8. The on-line control system for forming springs according to claim 7, wherein the data acquisition module is configured in a current loop control loop of the servo driver, the sampling frequency is not lower than 16kHz, and the disturbance observation module and the compensation calculation module are embedded in a Field Programmable Gate Array (FPGA) chip to realize microsecond data processing and instruction response.

Description

Spring forming on-line control system and control method Technical Field The invention relates to the technical field of precision spring manufacturing and automatic control, in particular to an online spring forming control system and a control method. Background Along with the rapid development of modern precision manufacturing technology, spring forming processing brings higher requirements on the consistency and production efficiency of products, however, random fluctuation of physical properties of raw material wires brings significant challenges to control of forming precision, at present, a traditional machine vision detection system or an off-line measurement method is generally adopted to monitor the size of the spring, the methods essentially belong to post detection, have obvious hysteresis and view field blind areas, can not capture and respond to the change of material characteristics at the moment when forming actions happen, and can not dynamically adjust forming tracks to counteract rebound errors in the processing process due to difficulty in sensing fluctuation of tensile strength or hardness of the wires in real time; therefore, how to sense the rheological property of the material in real time and perform dynamic geometric compensation in the high-speed forming process becomes a problem to be solved in the field. Disclosure of Invention In order to solve the technical problems, the invention provides an online control system and a control method for spring forming, and specifically, the technical scheme of the invention is as follows: An on-line control method for forming springs includes constructing a mechanical transmission dynamics reference model, acquiring servo motor operation parameters in real time, wherein the servo motor operation parameters comprise an actual current value, an actual position value and an actual speed value, calculating disturbance torque by using a disturbance observer, decoupling a material deformation impedance component from the disturbance torque, wherein the material deformation impedance component represents transient rheological characteristics of wires in a forming process, acquiring a preset elastoplastic compensation model, generating a position correction instruction in real time based on the material deformation impedance component and the elastoplastic compensation model, and superposing the position correction instruction to a target position instruction of a forming shaft to dynamically adjust a forming track in a current forming period. The method for constructing the mechanical transmission dynamics reference model comprises the steps of driving forming equipment to perform no-load operation test on a full-speed section to obtain no-load test data, extracting friction characteristics and inertia characteristics of a mechanical transmission chain based on the no-load test data, establishing a dynamics equation comprising coulomb friction, viscous friction and moment of inertia by utilizing the friction characteristics and the inertia characteristics, and marking the dynamics equation as the mechanical transmission dynamics reference model, wherein calculation logic of theoretical reference moment is that an actual speed value and an actual acceleration value are input into the mechanical transmission dynamics reference model, and moment components for overcoming self resistance of a mechanical system are calculated. The method for calculating the disturbance torque by using the disturbance observer comprises the steps of multiplying an actual current value by a preset motor torque constant to obtain an actual output torque, uniformly using the actual output torque to express subsequent calculation, subtracting a theoretical reference torque from the actual output torque to obtain a preliminary disturbance signal, performing low-pass filtering processing on the preliminary disturbance signal to inhibit high-frequency quantization noise, and marking the processed signal as the disturbance torque, wherein the bandwidth frequency of the disturbance observer is set to be higher than the wire forming characteristic frequency and lower than the current loop sampling frequency. The method for decoupling the material deformation impedance component from the disturbance torque comprises the steps of constructing a band-pass filter, inputting the disturbance torque into the band-pass filter, filtering low-frequency components caused by mechanical drift and high-frequency components caused by electromagnetic interference, obtaining a cleaned torque signal, calculating the product of the cleaned torque signal and an actual speed value, carrying out time integration on the product to obtain instantaneous forming energy density, and marking the instantaneous forming energy density as a material deformation impedance component, wherein the numerical value of the material deformation impedance component and the tensile strength of the wire are in positive cor