A laser welding machine temperature control method and system based on fuzzy control and device thereof

Abstract

The application discloses a laser welding machine temperature control method based on fuzzy control, comprising: continuously acquiring temperature parameters of a cold plate inside a laser welding machine and light output parameters of the laser welding machine; taking the first acquired temperature parameters and light output parameters as inputs of a fuzzy controller, and outputting a first temperature control strategy; after regulating the refrigerant flow for heat exchange inside the laser welding machine based on the first temperature control strategy, a PID controller continuously generates a second temperature control strategy for regulating the valve opening degree based on the difference between the temperature parameters updated at the current moment and the target temperature. The application outputs the first temperature control strategy in the initial stage of starting the laser welding machine to realize rapid adjustment of the system temperature, effectively prevents excessive temperature fluctuation, and the PID controller continuously generates the second temperature control strategy for regulating the valve opening degree, realizes accurate adjustment of the system temperature, further improves the temperature control effect, and solves the problems that the traditional laser welding machine temperature control method cannot adapt to power mutation and has poor temperature control effect.

Description

Technical Field

[0001] This invention relates to the field of laser welding machine technology, and specifically to a laser welding machine temperature control method, system and device based on fuzzy control. Background Technology

[0002] Laser welding machines, also known as laser welders or laser welding machines, are used for laser welding in material processing. Their working principle is as follows: high-energy laser pulses are used to locally heat a small area of ​​the material. The energy of the laser radiation diffuses into the material through heat conduction, melting the material to form a specific molten pool. As a novel welding method, it is mainly used for welding thin-walled materials and precision parts. It can perform spot welding, butt welding, lap welding, and sealing welding. It also boasts advantages such as a high aspect ratio, narrow weld width, small heat-affected zone, minimal deformation, fast welding speed, smooth and aesthetically pleasing welds, no or only simple post-weld treatment, high weld quality, no porosity, precise control, small focused spot, high positioning accuracy, and easy automation.

[0003] When a handheld welding machine is turned on at full power, its thermal power changes from 0 to 4000W within one second, and then instantly drops back to 0 upon shutdown, exhibiting a large abrupt change in power. If the heat cannot be dissipated within a few seconds of startup, it can cause optical components to overheat or even be damaged. However, traditional laser welding machine temperature control methods use PID control, which struggles to adjust for drastic power changes and is difficult to implement in systems with lag. Furthermore, traditional laser welding machine temperature control methods typically use water as a heat exchange medium. While water has a high specific heat capacity and strong heat buffering effect, resulting in smaller temperature fluctuations and lower control requirements, its slow heat exchange efficiency cannot meet the objective requirements of the aforementioned abrupt changes in thermal power.

[0004] In summary, traditional laser welding machine temperature control methods suffer from problems such as inability to adapt to sudden power changes and poor temperature control performance. Summary of the Invention

[0005] In view of this, the present invention provides a laser welding machine temperature control method based on fuzzy control. By improving data acquisition, data processing and control strategies, it solves the problems of traditional laser welding machine temperature control methods, such as inability to adapt to power fluctuations and poor temperature control effect.

[0006] To solve the above problems, the technical scheme of the present application is a laser welding machine temperature control method based on fuzzy control, comprising: continuously acquiring the temperature parameters of the cold plate inside the laser welding machine and the light output parameters of the laser welding machine; the first acquired temperature parameters and light output parameters are taken as the input of the fuzzy controller, and the first temperature control strategy is output; after the refrigerant flow for heat exchange inside the laser welding machine is regulated based on the first temperature control strategy, the PID controller continuously generates the second temperature control strategy for adjusting the valve opening degree based on the difference between the temperature parameters updated at the current time and the target temperature, wherein the valve opening degree is used to fine-tune the refrigerant flow.

[0007] Optionally, when the valve is configured to include a main valve and an auxiliary valve, the cold plate, the main valve, the external heat exchange device and the compressor form a main temperature control loop; the cold plate and the auxiliary valve form an auxiliary temperature control loop; wherein the refrigerant cooled by the external heat exchange device in the main temperature control loop is mixed with the refrigerant not cooled in the auxiliary temperature control loop in the passage between the external heat exchange device and the compressor.

[0008] Optionally, in the case where the valve is configured to include a main valve and an auxiliary valve, the method of generating the second temperature control strategy comprises: the PID controller continuously generates a control signal for adjusting the opening degree of the main valve based on the difference between the temperature parameters updated at the current time and the target temperature; the PID controller generates a control signal for adjusting the opening degree of the auxiliary valve based on the temperature difference of the refrigerant at both ends of the cold plate.

[0009] Optionally, the method of outputting the first temperature control strategy comprises: the fuzzy controller generates fuzzy set data after fuzzifying the temperature parameters and the light output parameters; the corresponding fuzzy control rules are called based on the fuzzy set data in the fuzzy control rule table; the first temperature control strategy is generated after the fuzzy control rules are defuzzified.

[0010] Optionally, the first temperature control strategy is configured to include the compressor frequency parameter and the valve opening degree, so as to regulate the refrigerant flow.

[0011] Optionally, the laser welding machine temperature control method further comprises: when the first acquired temperature parameters are lower than the optimal working temperature range, starting the electric auxiliary heating device on one side of the cold plate to heat the laser components on the other side of the cold plate away from the electric auxiliary heating device, until the temperature parameters updated at the current time belong to the optimal working temperature range, turning off the electric auxiliary heating device, starting the laser welding machine and taking the first acquired temperature parameters and light output parameters as the input of the fuzzy controller to output the first temperature control strategy.

[0012] Optionally, the laser welding machine temperature control method further comprises: after detecting that the light output parameter of the laser welding machine changes, taking the updated light output parameter and the first acquired temperature parameter as inputs of the fuzzy controller, and outputting an updated first temperature control strategy

[0013] Correspondingly, the application provides a laser welding machine temperature control system based on fuzzy control, comprising: a temperature control loop for heat exchange with the inside of the laser welding machine; a detection unit for continuously acquiring a temperature parameter of a cold plate inside the laser welding machine and a light output parameter of the laser welding machine; a data processing unit for taking the first acquired temperature parameter and light output parameter as inputs of a fuzzy controller of the data processing unit, outputting a first temperature control strategy, and based on the first temperature control strategy, continuously generating a second temperature control strategy for adjusting the valve opening degree based on the difference between the updated temperature parameter at the current time and the target temperature, wherein the valve opening degree is used to fine-tune the refrigerant flow.

[0014] Optionally, when the number of valves is 1, the temperature control loop comprises the cold plate, the valve, the external heat exchange device, and the compressor; when the valve is configured to include a main valve and an auxiliary valve, the temperature control loop comprises a main temperature control loop comprising the cold plate, the main valve, the external heat exchange device, and the compressor, and an auxiliary temperature control loop comprising the cold plate and the auxiliary valve and the compressor, wherein the refrigerant cooled by the external heat exchange device in the main temperature control loop and the refrigerant not cooled in the auxiliary temperature control loop are mixed in the passage between the external heat exchange device and the compressor.

[0015] Correspondingly, the application provides a laser welding machine temperature control device based on fuzzy control, comprising: a main temperature control loop comprising the cold plate, the main valve, the external heat exchange device, and the compressor; and an auxiliary temperature control loop comprising the cold plate and the auxiliary valve and the compressor; wherein the refrigerant cooled by the external heat exchange device in the main temperature control loop and the refrigerant not cooled in the auxiliary temperature control loop are mixed in the passage between the external heat exchange device and the compressor.

[0016] The primary improvement of the present application is to provide a laser welding machine temperature control method based on fuzzy control, which can effectively and quickly suppress large laser power fluctuations by using a coolant with small specific heat capacity as a heat conduction medium. At the same time, due to the small specific heat capacity of the coolant, there is a problem of large temperature fluctuation of the coolant. The present application uses the first acquired temperature parameter and light output parameter as the input of the fuzzy controller in the initial stage of the start of the laser welding machine, and outputs the first temperature control strategy to realize the rapid adjustment of the system temperature, effectively preventing the occurrence of excessive temperature fluctuation. After that, the PID controller continuously generates a second temperature control strategy for adjusting the valve opening based on the difference between the temperature parameter updated at the current time and the target temperature, realizing the accurate adjustment of the system temperature, further improving the temperature control effect, and solving the problem of the traditional laser welding machine temperature control method that cannot adapt to power mutation and poor temperature control effect. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a simplified flowchart of the laser welding machine temperature control method based on fuzzy control of the present application;

[0018] Figure 2 is a simplified unit connection diagram of the laser welding machine temperature control system based on fuzzy control of the present application;

[0019] Figure 3 is a simplified structure connection diagram of the laser welding machine temperature control device based on fuzzy control of the present application. DETAILED DESCRIPTION

[0020] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below in combination with the drawings and specific embodiments.

[0021] As shown in Figure 1 a laser welding machine temperature control method based on fuzzy control, comprising:

[0022] S1: continuously acquiring the temperature parameter of the internal cold plate of the laser welding machine and the light output parameter of the laser welding machine.

[0023] Further, considering the case that the ambient temperature is lower than the optimal working temperature interval of the laser welding machine, the application pre-sets the optimal working temperature interval, and when the first acquired temperature parameter is lower than the optimal working temperature interval, the electric auxiliary heating device on one side of the cold plate is started to heat the laser components on the other side of the cold plate away from the electric auxiliary heating device, until the temperature parameter updated at the current time belongs to the optimal working temperature interval, and after the electric auxiliary heating device is turned off, the laser welding machine is started and the first acquired temperature parameter and the light output parameter are used as inputs of the fuzzy controller to output the first temperature control strategy. Thus, before the laser welding machine works, the temperature parameter of the cold plate inside the laser welding machine is detected to represent the temperature of the laser related components inside the laser welding machine, so that the electric auxiliary heating device is used for heating to make the laser related components in the optimal working temperature interval, to ensure the light output efficiency of the laser and the working reliability of the laser welding machine. At the same time, by using the characteristic that the temperature parameter of the cold plate inside the laser welding machine is basically consistent with the ambient temperature before the laser welding machine works, the first acquired temperature parameter is reused to represent the ambient temperature, and it is used as an input of the fuzzy controller together with the light output parameter, so that it can be used for rapid adjustment of the system temperature.

[0024] S2: The first temperature control strategy is output by using the first acquired temperature parameter and the light output parameter as inputs of the fuzzy controller. The first temperature control strategy is configured to include the compressor frequency parameter and the valve opening degree, so as to regulate the refrigerant flow.

[0025] Further, the method of outputting the first temperature control strategy includes: the fuzzy controller generates fuzzy set data after fuzzifying the temperature parameter and the light output parameter; the corresponding fuzzy control rule is called based on the fuzzy set data in the fuzzy control rule table; and the first temperature control strategy is generated after the fuzzy control rule is defuzzified.

[0026] Further, when the valve is configured to include a main valve and an auxiliary valve, the first temperature control strategy is configured to include the compressor frequency parameter, the main valve opening degree and the auxiliary valve opening degree, so as to regulate the refrigerant flow.

[0027] S3: After the refrigerant flow for heat exchange with the laser welding machine is regulated based on the first temperature control strategy, the PID controller continuously generates the second temperature control strategy for adjusting the valve opening degree based on the difference between the temperature parameter updated at the current time and the target temperature, wherein the valve opening degree is used for fine adjustment of the refrigerant flow. The refrigerant can be R410A.

[0028] During the initial design of the temperature control loop, the inventors discovered that traditional single-temperature control loops often suffered from excessive suppression, leading to excessively low temperatures. The conventional approach to this problem involved switching between cooling and heating via a four-way valve. However, this method required a long time to establish system equilibrium and achieve a stable heat transfer balance, resulting in uncontrollable conditions and potential overheating or overcooling of the cold plate, causing uncontrollable cold plate temperature. Therefore, to address these issues, this invention configures the valves to include a main valve and an auxiliary valve. The cold plate, the main valve, the external heat exchanger, and the compressor constitute the main temperature control loop; the cold plate, the auxiliary valve, and the compressor constitute the auxiliary temperature control loop. The refrigerant cooled by the external heat exchanger in the main temperature control loop mixes with the uncooled refrigerant in the auxiliary temperature control loop in the passage between the external heat exchanger and the compressor. This allows for rapid correction of excessive suppression by controlling the opening of the auxiliary valve.

[0029] Meanwhile, the inventors discovered in practical use that the variability of laser welding machine usage scenarios leads to significant differences in ambient temperature. Under the same control strategy, the temperature control effect varies considerably across different usage scenarios. After conducting experiments controlling different influencing factors as independent variables and corresponding control groups, it was found that the ambient temperature of the usage scenario affects heat exchange efficiency to some extent. Therefore, this invention detects changes in ambient temperature and further adjusts the compressor frequency and valve opening to eliminate the impact of ambient temperature on heat exchange efficiency, thereby further improving the temperature control effect. Specifically, when the valves are configured to include a main valve and an auxiliary valve, the method for generating the second temperature control strategy includes: a PID controller continuously generating a control signal for adjusting the main valve opening based on the difference between the currently updated temperature parameter and the target temperature. Specifically, the PID controller continuously generates a control signal for adjusting the main valve opening based on the difference between the currently updated temperature parameter and the target temperature. The system calculates the rate of change of the temperature difference between the previous temperature parameter and the target temperature, and then generates a control signal to adjust the opening of the main valve based on the current temperature parameter, the difference between the current temperature parameter and the target temperature, and the rate of change of the difference. The PID controller generates a control signal to adjust the opening of the auxiliary valve based on the temperature difference of the refrigerant at both ends of the cold plate. Specifically, the PID controller calculates the numerical difference between the current temperature difference and the target temperature difference, and then calculates the rate of change of the numerical difference based on the current numerical difference and the numerical difference at the previous time. Finally, the PID controller generates a control signal to adjust the opening of the auxiliary valve based on the current numerical difference and the rate of change of the numerical difference. The target temperature difference is determined by the user based on the required heat exchange efficiency according to the operating environment; this invention does not impose specific limitations on it. Similarly, the target temperature is also set by the user according to the parameters of the laser welding machine equipment; this invention does not impose specific limitations on it.

[0030] Further, the basic working principle of the PID controller is that: based on the difference value of the input, the change rate of the difference value is calculated, and then Kp, Ki and Kd are determined based on the difference value and the change rate of the difference value to output the final control strategy, wherein the basic adjustment rule is: to improve the stability of the control system, the integral action is reduced, and a smaller Ki is taken.When the size of the deviation and the change rate of the deviation is moderate, Kp, Ki and Kd should be selected to be moderate, so as to avoid generating a larger overshoot.When the deviation is small, smaller Kp and larger Ki should be selected, which can improve the stability of the system, but in order to avoid oscillation phenomenon, when the value of the change rate of the deviation is small, Kd is larger, otherwise, Kd is smaller.

[0031] The present application can effectively and quickly suppress large laser power fluctuations by using a coolant with small specific heat capacity as a heat conducting medium, and since the specific heat capacity of the coolant is small, there is a problem of large temperature fluctuation of the coolant, the present application uses the first acquired temperature parameter and light output parameter as the input of the fuzzy controller of the data processing unit to output the first temperature control strategy to realize the rapid adjustment of the system temperature, effectively prevent the occurrence of high temperature fluctuation, and the PID controller continuously generates the second temperature control strategy for adjusting the valve opening degree based on the difference between the updated temperature parameter at the current time and the target temperature, realizes the accurate adjustment of the system temperature, further improves the temperature control effect, and solves the problem that the traditional laser welding machine temperature control method cannot adapt to power mutation and has poor temperature control effect.

[0032] Correspondingly, as shown in Figure 2 The present application provides a laser welding machine temperature control system based on fuzzy control, which comprises: a temperature control loop for heat exchange with the inside of the laser welding machine; a detection unit for continuously acquiring the temperature parameter of the cold plate inside the laser welding machine and the light output parameter of the laser welding machine; a data processing unit for taking the first acquired temperature parameter and light output parameter as the input of the fuzzy controller of the data processing unit, outputting the first temperature control strategy, and adjusting the coolant flow for heat exchange with the inside of the laser welding machine based on the first temperature control strategy, and the PID controller of the data processing unit continuously generates the second temperature control strategy for adjusting the valve opening degree based on the difference between the updated temperature parameter at the current time and the target temperature, wherein the valve opening degree is used to fine tune the coolant flow.

[0033] Further, when the number of valves is 1, the temperature control circuit comprises the cold plate, the valve, the external heat exchange device and the compressor; when the valve is configured to include a main valve and an auxiliary valve, the temperature control circuit comprises a main temperature control circuit comprising the cold plate, the main valve, the external heat exchange device and the compressor, and an auxiliary temperature control circuit comprising the cold plate, the auxiliary valve and the compressor, wherein the refrigerant cooled by the external heat exchange device in the main temperature control circuit and the refrigerant not cooled in the auxiliary temperature control circuit are mixed in the passage between the external heat exchange device and the compressor.

[0034] Correspondingly, as shown in the accompanying drawings, Figure 3 the application provides a laser welding machine temperature control device based on fuzzy control, characterized in that it comprises a main temperature control circuit comprising the cold plate, the main valve, the external heat exchange device and the compressor, and an auxiliary temperature control circuit comprising the cold plate, the auxiliary valve and the compressor, wherein the refrigerant cooled by the external heat exchange device in the main temperature control circuit and the refrigerant not cooled in the auxiliary temperature control circuit are mixed in the passage between the external heat exchange device and the compressor.

[0035] Further, the external heat exchange device can be composed of a condenser and a fan; the main valve and the auxiliary valve can both be electronic expansion valves.

[0036] Further, the laser welding machine temperature control device further comprises a first temperature sensor for detecting the temperature parameter of the cold plate, a second temperature sensor for detecting the temperature of the refrigerant at one end of the compressor and a third temperature sensor for detecting the temperature of the refrigerant at the other end of the compressor, and an electric auxiliary heating device for preheating the laser welding machine.

[0037] The above describes a laser welding machine temperature control method, system and device based on fuzzy control provided by the embodiments of the application. The embodiments in the specification are described in a progressive manner, and each embodiment mainly describes the differences from other embodiments. The same or similar parts of each embodiment can be understood by referring to each other. For the device disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the relevant parts can be understood by referring to the method part. It should be noted that, for those skilled in the art, without departing from the principle of the application, the application can be improved and modified in several ways, and these improvements and modifications also fall within the protection scope of the claims of the application.

[0038] Those skilled in the art will further realize that the mere conception of the examples described herein is not a patentable device, composition or process. The embodiments described herein with respect to the examples include physical devices, compositions and processes, apparatuses and methods. The apparatuses and methods can be implemented in a number of different physical devices and compositions. Depending on the embodiment, certain of the examples can be implemented in software, in firmware, or in hardware. The examples can be implemented in one or more computer programs operating on one or more programmable computers generating individual instructions (program modules) executable at one or more programmable computers to perform the operations described. The program modules can be stored in any type of computer readable medium, such as those described above. Further, those skilled in the art will appreciate that one or more examples described herein can be practiced with electrical circuitry, directly coupled or remotely coupled through one or more buses and the like, with respect to which electrical circuitry takes the form of a combination of analog and digital circuits, a combination of analog and digital circuitry, or entirely digital circuitry or components, or the like.

Claims

1. A laser welding machine temperature control method based on fuzzy control, characterized in that, include: Continuously acquire the temperature parameters of the cold plate inside the laser welding machine and the output parameters of the laser welding machine; The temperature parameters and light emission parameters obtained for the first time are used as inputs to the fuzzy controller to output the first temperature control strategy; The method for outputting the first temperature control strategy includes: the fuzzy controller fuzzifies the temperature parameter and the light output parameter to generate fuzzy set data; Based on the fuzzy set data, the corresponding fuzzy control rule is invoked in the fuzzy control rule table; The first temperature control strategy is generated by defuzzifying the fuzzy control rules. After regulating the refrigerant flow rate for heat exchange with the laser welding machine based on the first temperature control strategy, the PID controller continuously generates a second temperature control strategy for adjusting the valve opening based on the difference between the updated temperature parameter at the current moment and the target temperature. The valve opening is adjusted to fine-tune the refrigerant flow rate. When the valve is configured to include a main valve and an auxiliary valve, the cold plate, the main valve, the external heat exchange device, and the compressor constitute the main temperature control circuit. The cold plate, auxiliary valves, and compressor constitute an auxiliary temperature control circuit; wherein... The refrigerant cooled by the external heat exchanger in the main temperature control loop and the uncooled refrigerant in the auxiliary temperature control loop are mixed in the passage between the external heat exchanger and the compressor; when the valve is configured to include a main valve and an auxiliary valve, the method for generating the second temperature control strategy includes: the PID controller continuously generates a control signal for adjusting the opening of the main valve based on the difference between the temperature parameter updated at the current moment and the target temperature; The PID controller generates a control signal for adjusting the opening of the auxiliary valve based on the temperature difference of the refrigerant at both ends of the cold plate.

2. The laser welding machine temperature control method according to claim 1, characterized in that, The first temperature control strategy is configured to include: compressor frequency parameters and valve opening, thereby regulating refrigerant flow.

3. The laser welding machine temperature control method according to claim 1, characterized in that, The laser welding machine temperature control method further includes: when the temperature parameter obtained for the first time is lower than the optimal operating temperature range, activating the electric auxiliary heating device on one side of the cold plate to heat the laser components on the other side of the cold plate away from the electric auxiliary heating device, until the temperature parameter updated at the current moment belongs to the optimal operating temperature range, turning off the electric auxiliary heating device, turning on the laser welding machine and using the temperature parameter obtained for the first time and the light output parameter as inputs to the fuzzy controller, and outputting the first temperature control strategy.

4. The laser welding machine temperature control method according to claim 1, characterized in that, The laser welding machine temperature control method further includes: after detecting a change in the laser welding machine's output parameters, using the updated output parameters and the initially acquired temperature parameters as inputs to a fuzzy controller, and outputting an updated first temperature control strategy.

5. A laser welding machine temperature control system based on fuzzy control, used to deploy the laser welding machine temperature control method according to any one of claims 1 to 4, characterized in that, include: The temperature control circuit is used for heat exchange with the interior of the laser welding machine; The detection unit continuously acquires the temperature parameters of the cold plate inside the laser welding machine and the output parameters of the laser welding machine; The data processing unit takes the temperature parameters and light output parameters acquired for the first time as inputs to the fuzzy controller of the data processing unit, outputs a first temperature control strategy, and adjusts the flow rate of the refrigerant used for heat exchange with the inside of the laser welding machine based on the first temperature control strategy. The PID controller of the data processing unit continuously generates a second temperature control strategy for adjusting the valve opening based on the difference between the temperature parameters updated at the current time and the target temperature. The valve opening is adjusted to fine-tune the refrigerant flow rate.

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