CN116179840A - Laser surface heat treatment temperature monitoring control system and control method - Google Patents

Laser surface heat treatment temperature monitoring control system and control method Download PDF

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CN116179840A
CN116179840A CN202211738796.1A CN202211738796A CN116179840A CN 116179840 A CN116179840 A CN 116179840A CN 202211738796 A CN202211738796 A CN 202211738796A CN 116179840 A CN116179840 A CN 116179840A
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temperature
control
parameters
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heat treatment
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张群莉
张凯
陈智君
姚建华
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Zhejiang University of Technology ZJUT
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D11/00—Process control or regulation for heat treatments
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/06—Surface hardening
    • C21D1/09—Surface hardening by direct application of electrical or wave energy; by particle radiation
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/62—Quenching devices
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P90/00—Enabling technologies with a potential contribution to greenhouse gas [GHG] emissions mitigation
    • Y02P90/02—Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

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Abstract

The invention relates to the field of laser processing heat treatment, in particular to a laser surface heat treatment temperature monitoring control system and a control method. The laser surface heat treatment temperature monitoring control system comprises an upper computer, a switch, a PLC controller, a sensor and an HMI display, and the control method comprises the following steps: and (3) carrying out real-time strategy and record on the surface temperature of the workpiece in the laser heat treatment process, carrying out real-time temperature measurement on the laser heat treatment process, fitting an actual temperature change curve according to limited measured data, further judging the temperature deviation reason according to the temperature change trend, and making a corresponding regulation strategy so as to optimize and improve the overall processing quality.

Description

Laser surface heat treatment temperature monitoring control system and control method
Technical Field
The invention relates to the technical field of laser processing heat treatment, in particular to a laser surface heat treatment temperature monitoring control system and a control method.
Background
The laser heat treatment is a quenching technology which heats the surface of the material above a phase transition point by utilizing laser, and the phase transition of the corresponding material occurs along with the self cooling of the material, thereby hardening the surface of the material. The laser quenching hardening layer is uniform, the hardness is high (generally 1-3HRC higher than induction quenching), the deformation of a workpiece is small, the depth of a heating layer and a heating track are easy to control, and automation is easy to realize.
The conventional heat treatment needs to design corresponding induction coils according to different part sizes, and the machining of large parts is not limited by the size of a hearth during the chemical heat treatment such as carburizing and quenching.
The patent number is CN202110558590.X invention discloses an outer cladding laser heat treatment device for alloy material parts, which solves the problem of lower heat treatment precision of laser surfaces, but adopts fixed parameters for processing in the processing process, cannot cope with quality difference caused by larger heat accumulation in the processing process, lacks feedback control in the control process, and still has larger improvement space. The invention patent number CN202010920105.4 discloses a laser quenching quality uniformity control method and device, wherein an infrared temperature detector is used for detecting the temperature of the surface of a workpiece in a quenching zone, so that the laser quenching temperature is detected on line, the problem that the existing laser quenching equipment cannot realize real-time feedback and timely adjustment is solved, and the consistency of indexes such as the surface hardness and the depth of a hardening layer of the workpiece is controlled. Although the temperature sensor is obviously improved, the problems of larger temperature measurement deviation of the sensor caused by laser reflection, surface impurities and the like are not considered. In particular, there are great limitations to the processing of profiled workpieces. The patent discloses a temperature monitoring control system and a control method aiming at laser heat treatment.
Disclosure of Invention
Aiming at the problems that the temperature of a processing area is not uniform in a conventional heat treatment mode, the processing quality is not uniform due to incapability of timely regulating and controlling when a large temperature error occurs, and the like in the processing process, the invention aims to provide a laser surface heat treatment temperature monitoring control system and a control method which are high in efficiency, accurate in temperature control and automatic in processing, and by the method, the temperature gradient of the processing area can be reduced, so that the surface hardness of a workpiece and the uniformity of distribution are improved.
The invention realizes the above purpose through the following technical scheme: the laser surface heat treatment temperature monitoring control system comprises an upper computer, a switch, a PLC (programmable logic controller), a sensor and an HMI (human machine interface) display, wherein the PLC is connected with the switch and the upper computer through an RJ45 network cable, uploads collected related parameters and analyzes the data in real time, so that real-time calculation of a complex control process is realized; the PLC is connected with a temperature sensor through RS485 and collects temperature signals of the temperature sensor; the PLC is connected with the HMI display through an RJ45 network cable and synchronously displays related parameters; the PLC controller controls the execution mechanisms such as the laser, the machine tool, the sensor, the movement device and the like through the I/O serial port, the upper computer responds the data analysis result to the PLC controller, and the execution mechanism executes the control parameters calculated by the upper computer to realize the adjustment of movement and related parameters.
Furthermore, the invention is provided with a plurality of temperature signal measuring points on the workpiece, the temperature sensor transmits the monitored temperature to the DB block in the PLC controller in a parallel mode, the DB block makes data packets according to a set data transmission protocol, and the data packets are uploaded to the upper computer real-time data analysis system through the data protocol.
Furthermore, the invention also defines that the distance between two adjacent temperature signal measuring points is 8-15mm, and the temperature measuring period is not less than 5 times per second.
Furthermore, the invention also defines a control method based on the laser surface heat treatment temperature monitoring control system, which comprises the following steps:
1) Placing the pretreated workpiece to be processed in an initial fixed station, then setting processing parameters by an upper computer, starting processing after the parameter setting is completed, and starting the corresponding executive component to work;
2) After processing, the temperature sensor starts to measure temperature, the temperature signal acquisition system transmits the measured real-time temperature, power, time and the like to the upper computer for storing historical data and calculating data such as temperature fitting, temperature gradient variance and the like, and meanwhile, the temperature of a processing area is calculated according to a temperature transfer function;
3) Meanwhile, fitting a temperature curve according to the actually measured temperature information, extracting multiple points on the temperature curve and storing the multiple points so as to refine temperature judgment among all measurement points, wherein the fitted curve is used as a judgment basis for the actual temperature curve and change of a workpiece;
4) The temperature control system judges the parameters calculated according to the real-time data analysis system according to the calculated data, decides whether to regulate and control the corresponding execution components such as laser power according to the result, dynamically adjusts according to the measured temperature and the related calculation result, and calculates the real-time heat conduction physical state of the workpiece surface according to the formula, thereby realizing trend judgment and target adjustment of the temperature, and the related heat conduction formula is as follows:
heat quantity
Figure BDA0004030689630000041
Wherein: lambda is the coefficient of thermal conductivity, A is the contact area, t 1 ,t 2 The temperature between two points is x is the plate thickness, delta t is the temperature difference, and R is the thermal resistance;
5) The regulation and control is based on sensor feedback parameters, and measurement is attributed to one of a plurality of process states according to a Bayesian method, and the regulation and control is used as a means for classifying process deviation; predicting the severity of the deviation on the quality impact according to a least squares regression model;
6) If a regulation and control instruction is acquired, matching and searching are carried out according to parameters in a parameter database, if the completely matched parameters cannot be searched, calculation is automatically carried out according to similar parameters to obtain required regulation and control parameters, and the required regulation and control parameters are packaged and sent to internal control parameters of a PLC (programmable logic controller) according to a set transmission protocol, so that regulation and control are implemented;
7) After executing the corresponding regulation and control instruction, the next temperature measurement period judges whether the temperature change value meets the expected target, if the difference between the actual measurement value and the regulation and control value still exceeds the system set threshold, an alarm signal is sent out and corresponding regulation and control is carried out, the power regulation value is calculated and executed until the processing is completed, the buffer is emptied, and the processing process is finished;
8) And finally, matching the temperature data value with the color lump to generate a temperature cloud picture, and judging the processing quality according to the temperature cloud picture data.
Furthermore, the invention also defines that the fitting temperature curve in the step 3) adopts an interpolation method and a Newton iteration method, and the curve obtained by fitting is used as a judging basis for the actual temperature curve and the change of the workpiece.
Further, the invention also defines that the regulation parameters in the step 4) comprise laser power parameters, cooling flow parameters and auxiliary temperature control device parameters.
Further, the invention also defines that three-level threshold judgment is set in the step 7), wherein the three-level threshold judgment comprises a phase change threshold, a melting point threshold and a danger threshold, the threshold ranges are sequentially from small to large, if the phase change threshold is triggered, a temperature abnormality prompt is sent out, and actions are automatically corrected and recorded; if the melting point threshold is triggered, alarm information is sent to remind on-site personnel, a correction control value is calculated, and further correction actions are carried out; if the dangerous threshold is triggered, the processing process is directly stopped, a dangerous alarm is sent out, the state is recorded, and the processing is finished.
By adopting the technology, compared with the prior art, the invention has the beneficial effects that: according to the invention, by carrying out real-time temperature measurement on the laser quenching process and fitting an actual temperature change curve according to limited data, a corresponding regulation strategy is further made according to the temperature change trend, so that the overall processing quality is optimized and improved. And according to the regulating and controlling process value in each processing process, the regulating and controlling algorithm is gradually optimized, the temperature fluctuation is controlled within 5%, the repeated processing deviation is lower than 2.4%, and the processing quality is stably improved. Thereby leading the hardness distribution of the hardening layer on the surface to be more uniform.
Drawings
FIG. 1 is a hardware block diagram of a laser surface heat treatment temperature monitoring control system of the present invention;
FIG. 2 is a flow chart of a laser surface heat treatment temperature monitoring control method of the present invention;
FIG. 3 is a flow chart of a threshold strategy for a laser surface heat treatment temperature monitoring method in the present invention;
FIG. 4 is a temperature cloud image finally generated in embodiment 1;
fig. 5 is a temperature cloud image finally generated in embodiment 2.
In the figure: 1. an upper computer; 2. a switch; 3. a PLC controller; 4. an HMI display; 5. a laser; 6. a machine tool; 7. an inductor; 8. a movement device; 9. sensor, 10, laser head.
Detailed Description
The invention is further described below with reference to the accompanying drawings, but the scope of the invention is not limited thereto:
as shown in fig. 1, the hardware of the laser surface heat treatment temperature monitoring control system comprises an upper computer 1, a switch 2, a PLC (programmable logic controller) 3, an HMI (human machine interface) display 4 and a sensor 9, wherein the PLC 3 is connected with the switch 2 and the upper computer 1 through an RJ45 network cable, uploads collected related parameters and analyzes real-time data so as to realize real-time calculation of a complex control process; the PLC 3 is connected with the sensor 9 through an RS485, and collects temperature signals of the temperature sensor; the PLC 3 is connected with the HMI display 4 through an RJ45 network cable and synchronously displays related parameters; the PLC 3 controls the execution mechanisms such as the laser 5, the machine tool 6, the sensor 7, the movement device 8 and the like through an I/O serial port, the laser head 10 is arranged on the laser 5, the movement device 8 in the embodiment of the invention is a workpiece movement platform, the upper computer 1 reflects the data analysis result to the PLC, the execution mechanism executes the control parameters calculated by the upper computer to realize the adjustment of movement and related parameters, the sensor 9 is an infrared temperature sensor, and the invention can be provided with a plurality of infrared temperature sensors.
The invention discloses software of a laser surface heat treatment temperature monitoring control system, which comprises an equipment communication system, a temperature signal acquisition system and a real-time data analysis system. In the device communication system, a PLC 3 performs data communication with an upper computer 1 through an RJ45 network cable by using a PROFINET bus, and uploads relevant parameters of an execution device so as to realize real-time calculation of a complex control process; data communication is carried out with the HMI display 4 through an RJ45 network cable so as to synchronously display related parameters; real-time temperature data are acquired through an RS485 bus with an infrared temperature sensor, so that temperature data in the processing process are acquired; the control parameters obtained by calculation of an upper computer are executed by controlling execution mechanisms such as a laser 5, a machine tool 6, an inductor 7, a movement device 8, a water cooling spray head and the like through serial ports, so that the movement and the adjustment of related parameters are realized.
The temperature signal acquisition system determines a plurality of temperature signal measurement points according to a workpiece processing area in a laser heat treatment process, monitors the measurement points according to the determined distance and the determined temperature measurement period, and transmits signals to a DB block in the PLC in a parallel mode, wherein the DB block is used for grouping data according to a set data transmission protocol, and the data are uploaded to the upper computer real-time data analysis system through the data protocol.
The real-time data analysis system receives the real-time temperature signal data packet uploaded by the signal acquisition system, splits the data according to a data transmission protocol, reconstructs the data, extracts the temperature signal and completes the functions of corresponding calculation, display and analysis.
And the data reconstruction stores the obtained temperature signal into a preset data structure, repacks and stores the temperature signal and information such as real-time processing parameters, time and the like to form formatted data for subsequent complex calculation and analysis.
And the display function of the data is responsible for graphically displaying formatted data content, fitting measured temperature point data into temperature curve data, and respectively storing measured temperature values and fitted temperature values in different arrays for subsequent analysis. And constructing a temperature cloud picture of the processing process according to the storage temperature array, and matching pixel colors corresponding to the cloud picture according to system preset so as to analyze the trend of the corresponding processing process.
And the data calculation and analysis function is to reversely calculate the temperature value of the laser irradiation area according to the heat conduction equation by using the formatted data, judge correspondingly according to the calculated temperature value and the multi-stage temperature threshold, immediately send early warning information after the temperature value triggers the corresponding threshold, and send out related alarm signals and regulation and control instructions.
The invention discloses a temperature control method based on the laser surface heat treatment temperature monitoring control system, which comprises the following steps: and placing the pretreated workpiece to be processed in an initial fixing station, and then setting processing parameters in the upper computer 1. According to the shape, size and material of the workpiece to be processed, the system automatically matches corresponding preset parameters, and the specific parameters are customized by a user. After the parameter setting is completed, the process can be started. After the processing is started, the temperature signal acquisition system and the real-time data analysis system are automatically executed, and meanwhile, the temperature control system is started to operate.
The temperature control system calculates the parameters according to the real-time data analysis system, if a regulation and control instruction is acquired, the parameters in the parameter database are matched and searched, if the completely matched parameters cannot be searched, the required regulation and control parameters are automatically calculated according to the similar parameters, and the required regulation and control parameters are packaged and sent to the PLC internal control parameters according to a set transmission protocol, so that regulation and control are implemented.
The regulation will be based on sensor feedback parameters, and will attribute the measurement to one of a plurality of process states according to a bayesian method as a means of classifying process deviations; furthermore, the severity of the bias impact on quality will also be predicted from the least squares regression model.
The regulation and control parameters comprise laser power parameters, cooling flow parameters and auxiliary temperature control device parameters. After corresponding regulation and control instructions are transmitted, the next temperature measurement period is used for judging whether the temperature change value meets the expected target, and if the difference between the actual measurement value and the regulation and control value exceeds the threshold value, the regulation and control process is continuously executed. Finally, the verification construction is run by using different process parameter changes to verify the accuracy of regulation.
The regulation algorithm comprises PID control, model prediction control and database matching control obtained by simulation. In the actual regulation and control process, three regulation and control algorithms are calculated in parallel, and multi-level threshold judgment is set according to the difference value between the measured temperature value and the preset temperature value, so that the regulation and control force is gradually increased, and the aim of controlling the temperature is fulfilled.
The invention relates to a control method based on a laser surface heat treatment temperature monitoring control system, which comprises the following steps:
1) Placing the pretreated workpiece to be processed in an initial fixed station, then setting processing parameters by an upper computer, starting processing after the parameter setting is completed, and starting the corresponding executive component to work;
2) After processing, the temperature sensor starts to measure temperature, the temperature signal acquisition system transmits the measured real-time temperature, power, time and the like to the upper computer for storing historical data and calculating data such as temperature fitting, temperature gradient variance and the like, and meanwhile, the temperature of a processing area is calculated according to a temperature transfer function;
3) Meanwhile, fitting a temperature curve according to the actually measured temperature information, extracting multiple points on the temperature curve and storing the multiple points so as to refine temperature judgment among all measurement points, wherein the fitted curve is used as a judgment basis for the actual temperature curve and change of a workpiece;
4) The temperature control system judges the parameters calculated according to the real-time data analysis system according to the calculated data, decides whether to regulate and control the corresponding execution components such as laser power according to the result, dynamically adjusts according to the measured temperature and the related calculation result, and calculates the real-time heat conduction physical state of the workpiece surface according to the formula, thereby realizing trend judgment and target adjustment of the temperature, and the related heat conduction formula is as follows:
heat quantity
Figure BDA0004030689630000091
Wherein: lambda is the coefficient of thermal conductivity, A is the contact area, t 1 ,t 2 The temperature between two points is x is the plate thickness, delta t is the temperature difference, and R is the thermal resistance;
5) The regulation and control is based on sensor feedback parameters, and measurement is attributed to one of a plurality of process states according to a Bayesian method, and the regulation and control is used as a means for classifying process deviation; predicting the severity of the deviation on the quality impact according to a least squares regression model;
6) If a regulation and control instruction is acquired, matching and searching are carried out according to parameters in a parameter database, if the completely matched parameters cannot be searched, calculation is automatically carried out according to similar parameters to obtain required regulation and control parameters, and the required regulation and control parameters are packaged and sent to internal control parameters of a PLC (programmable logic controller) according to a set transmission protocol, so that regulation and control are implemented;
7) After executing the corresponding regulation and control instruction, the next temperature measurement period judges whether the temperature change value meets the expected target, if the difference between the actual measurement value and the regulation and control value still exceeds the system set threshold, an alarm signal is sent out and corresponding regulation and control is carried out, the power regulation value is calculated and executed until the processing is completed, the buffer is emptied, and the processing process is finished;
8) And finally, matching the temperature data value with the color lump to generate a temperature cloud picture, and judging the processing quality according to the temperature cloud picture data.
Example 1: using workpieces already in the system
As shown in fig. 2, when the control system is started, a series of parameter settings are needed to perform the corresponding functions, and the basic parameter settings include laser power, workpiece size, workpiece material and processing speed; since the existing technology is already built in the system, other relevant parameters will be automatically calculated according to the existing parameters.
After the parameter setting is completed, the processing process can be started, and the corresponding execution component starts working. Once the processing is completed, the temperature sensor starts to measure the temperature, and the measured real-time temperature is used for storing historical data and calculating data such as temperature gradient variance. The program automatically transmits the data acquired by the related temperature data, fitting data, power, time and the like to the upper computer for storage and complex calculation.
Because of the number limitation of the temperature sensors, curve fitting is carried out on measured data so as to refine temperature judgment among all measurement points and further optimize related decisions. The fitting method adopts an interpolation method and a Newton iteration method, and a curve obtained by fitting is used as a judging basis for the actual temperature curve and the change of the workpiece.
After the data of one time node is collected, the upper computer judges according to the calculated data, and decides whether to regulate and control the corresponding executing component such as laser power according to the result. And dynamically adjusting according to the measured temperature and the related calculation result. The related heat conduction formula is as follows:
heat quantity
Figure BDA0004030689630000111
Wherein: lambda is the coefficient of thermal conductivity, A is the contact area, t 1 ,t 2 The temperature between two points is x is the plate thickness, delta t is the temperature difference, and R is the thermal resistance; according to the formula, the real-time heat conduction physical state of the surface of the workpiece can be calculated, so that trend judgment and target adjustment of the temperature are realized.
If the calculated temperature value exceeds the set threshold value of the system, an alarm signal is sent out and corresponding regulation is carried out, and whether the regulation meets the expected target is judged on the temperature measurement result at the next temperature measurement moment. If the difference value between the actual measurement value and the regulation target exceeds the threshold value, the regulation process of the next period is carried out.
As shown in fig. 3, the system sets three-level threshold judgment, including a phase transition temperature threshold (first level), a melting point threshold (second level) and a danger threshold (third level). The threshold ranges are sequentially from small to large, if the first-level threshold is triggered, automatic correction action is carried out, and corresponding reminding and recording are sent out; if the second-level threshold is triggered, alarm information is sent to remind on-site personnel, and further correction actions are carried out; if the three-level threshold is triggered, the machining process is directly stopped and a dangerous alarm is sent out.
When the whole processing process is finished, a temperature cloud chart is generated according to the temperature and process state information stored by the upper computer, and the state condition of the whole processing process is intuitively displayed as shown in fig. 4 (according to the data in the chart, the continuous increase caused by temperature accumulation and the continuous decrease of the temperature caused by overshoot do not occur in the whole processing process, so that the temperature cloud chart has stronger stability). And clears the cache information in the controller to prepare for the next process.
Example 2: using types of dimensions of workpieces not provided for in the system
As shown in fig. 2, when the control system is started, a series of parameter settings including laser power, workpiece size, workpiece material, processing speed are performed; because the existing process library does not have the processing technology of the workpiece with the size, the processing process depends on a temperature control system for real-time calculation.
After the parameter setting is completed, the processing process can be started, and the corresponding execution component starts working. Once the processing is completed, the temperature sensor starts to measure the temperature, and the measured real-time temperature is used for storing historical data and calculating data such as temperature gradient variance. The program automatically transmits the data acquired by the related temperature data, fitting data, power, time and the like to the upper computer for storage and complex calculation.
After the processing is finished, the temperature change process in the processing process can be seen according to the temperature cloud chart of fig. 5, and the fact that the initial temperature is slightly lower due to the fact that the processing parameters of the workpiece are not in the system database at the beginning of the processing can be found, the expected regulation and control target is achieved through twice correction of the temperature control system, the temperature stability is maintained in the subsequent processing process, and the processing quality is controlled.
Finally, it should be pointed out that the above examples are only presented in detail by way of one of the laser surface quenching temperature monitoring methods provided by the present invention, and it is obvious that the invention is not limited to the above-described embodiments, and that various corresponding changes and modifications are given according to the inventive idea, and all such changes and modifications are intended to be included within the scope of the appended claims.

Claims (7)

1. The laser surface heat treatment temperature monitoring control system comprises an upper computer, a switch, a PLC controller, a sensor and an HMI display, and is characterized in that the PLC controller and the HMI display are in communication connection with the upper computer through an RJ45 network cable and the switch, and the PLC controller uploads relevant parameters acquired by the sensor and performs real-time data analysis on the upper computer to realize real-time calculation of a complex control process; the PLC is connected with a temperature sensor through RS485 and collects temperature signals of the temperature sensor; the PLC is connected with the HMI display through an RJ45 network cable and synchronously displays related parameters; the PLC controller controls the execution mechanisms such as the laser, the machine tool, the sensor, the movement device and the like through the I/O serial port, the upper computer responds the data analysis result to the PLC controller, and the execution mechanism executes the control parameters calculated by the upper computer to realize the adjustment of movement and related parameters.
2. The laser surface heat treatment temperature monitoring control system according to claim 1, wherein a plurality of temperature signal measuring points are arranged on a workpiece, the temperature sensor transmits the monitored temperature to a DB block in the PLC controller in a parallel mode, the DB block forms a data packet according to a set data transmission protocol, and the data packet is uploaded to the upper computer real-time data analysis system through a communication protocol.
3. The laser surface heat treatment temperature monitoring control system according to claim 1, wherein the distance between two adjacent temperature signal measuring points is 8-15mm, and the temperature measuring period is not less than 5 times per second.
4. A control method based on the laser surface heat treatment temperature monitoring control system according to any one of claims 1 to 3, characterized by comprising the steps of:
1) Placing the pretreated workpiece to be processed in an initial fixed station, then setting processing parameters by an upper computer, starting processing after the parameter setting is completed, and starting the corresponding executive component to work;
2) After processing, the temperature sensor starts to measure temperature, the temperature signal acquisition system transmits the measured real-time temperature, power, time and the like to the upper computer for storing historical data and calculating data such as temperature fitting, temperature gradient variance and the like, and meanwhile, the temperature of a processing area is calculated according to a temperature transfer function;
3) Meanwhile, fitting a temperature curve according to the actually measured temperature information, extracting multiple points on the temperature curve and storing the multiple points so as to refine temperature judgment among all measurement points, wherein the fitted curve is used as a judgment basis for the actual temperature curve and change of a workpiece;
4) The temperature control system judges the parameters calculated according to the real-time data analysis system according to the calculated data, decides whether to regulate and control the corresponding execution components such as laser power according to the result, dynamically adjusts according to the measured temperature and the related calculation result, and calculates the real-time heat conduction physical state of the workpiece surface according to the formula, thereby realizing trend judgment and target adjustment of the temperature, and the related heat conduction formula is as follows:
heat quantity
Figure FDA0004030689620000021
Wherein: lambda is the coefficient of thermal conductivity, A is the contact area, t 1 ,t 2 The temperature between two points is x is the plate thickness, delta t is the temperature difference, and R is the thermal resistance;
5) The regulation and control is based on sensor feedback parameters, and measurement is attributed to one of a plurality of process states according to a Bayesian method, and the regulation and control is used as a means for classifying process deviation; predicting the severity of the deviation on the quality impact according to a least squares regression model;
6) If a regulation and control instruction is acquired, matching and searching are carried out according to parameters in a parameter database, if the completely matched parameters cannot be searched, calculation is automatically carried out according to similar parameters to obtain required regulation and control parameters, and the required regulation and control parameters are packaged and sent to internal control parameters of a PLC (programmable logic controller) according to a set transmission protocol, so that regulation and control are implemented;
7) After corresponding regulation and control instructions are transmitted, the next temperature measurement period judges whether the temperature change value meets the expected target, if the difference between the actual measurement value and the regulation and control value exceeds the set threshold value of the system, an alarm signal is sent out and corresponding regulation and control are carried out, the power regulation value is calculated and executed until the processing is completed, the buffer memory is emptied, and the processing process is finished;
8) And finally, matching the temperature data value with the color lump to generate a temperature cloud picture, and judging the processing quality according to the temperature cloud picture data.
5. The method for monitoring and controlling the temperature of the laser surface heat treatment according to claim 4, wherein the fitted temperature curve in the step 3) adopts an interpolation method and a Newton iteration method, and the fitted curve is used as a judgment basis for the actual temperature curve and the change of the workpiece.
6. The method according to claim 4, wherein the control parameters in step 4) include a laser power parameter, a cooling flow parameter, and an auxiliary temperature control device parameter.
7. The method for monitoring and controlling the temperature of the laser surface heat treatment according to claim 4, wherein three-level threshold judgment is set in the step 7), the threshold range comprises a phase change threshold, a melting point threshold and a danger threshold, the threshold ranges from small to large in sequence, if the phase change threshold is triggered, a temperature abnormality prompt is sent out, and actions are automatically corrected and recorded; if the melting point threshold is triggered, alarm information is sent to remind on-site personnel, a correction control value is calculated, and further correction actions are carried out; if the dangerous threshold is triggered, the processing process is directly stopped, a dangerous alarm is sent out, the state is recorded, and the processing is finished.
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117311415A (en) * 2023-11-28 2023-12-29 南通进宝机械制造有限公司 Temperature monitoring system for steel part machining

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117311415A (en) * 2023-11-28 2023-12-29 南通进宝机械制造有限公司 Temperature monitoring system for steel part machining
CN117311415B (en) * 2023-11-28 2024-04-19 南通进宝机械制造有限公司 Temperature monitoring system for steel part machining

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