Thermal parameter measuring system for simulating laser-assisted processing and measuring method thereof

Abstract

The invention provides a thermal parameter measurement system for simulating laser-assisted processing and a measurement method thereof, and belongs to the technical field of material thermophysical properties. The system comprises a laser generator and a laser controller, the laser controller is connected with the laser generator through a circuit, a measuring device is arranged below the laser generator, one side of the measuring device is connected with a liquid supply cooling system, and the measuring device is used for simulating a workpiece in cooling machining; the other side of the measuring device is connected with a temperature monitoring system used for monitoring the temperature of the surface of the workpiece in real time. Through construction and calculation processing of a thermal parameter model, the system can obtain the laser absorptivity of a material and the convective heat transfer coefficient of cooling liquid, and finally precise modeling of a temperature field is achieved so as to guide adjustment of device parameters in actual machining.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal properties of materials, and in particular to a thermal parameter measurement system and a measurement method thereof for simulating laser-assisted processing. Background Art

[0002] Hard and brittle materials such as glass, ceramics and semiconductors, which usually have properties such as high strength, wide energy band gap and chemical inertness, have become important candidates, especially for critical components in harsh environments. However, due to their high strength and brittleness, they have long been regarded as difficult materials to machine, which will increase tool wear and limit surface integrity. Although grinding, lapping and polishing are common methods to obtain damage-free surfaces of hard and brittle materials, these methods are usually time-consuming and costly.

[0003] In recent years, laser-assisted processing technology has attracted much attention as an efficient processing method. By focusing the laser energy on the workpiece surface, laser-assisted processing technology can achieve fine processing and shape correction of hard and brittle materials. Compared with traditional processing methods, laser-assisted processing has the advantages of lower tool wear and better processing efficiency, and can maintain a certain processing accuracy. Therefore, laser-assisted processing technology has broad application prospects in aerospace, thermodynamics, photonics, and optical imaging.

[0004] In the existing laser-assisted processing, the laser energy and the flow rate of the workpiece coolant supply need to be adjusted according to the actual processing conditions, which makes it difficult to ensure the effective use of laser energy and the surface processing quality of the workpiece. However, by studying the two very critical thermal parameters, the absorption rate of the workpiece material to the laser and the heat transfer coefficient between the workpiece material and the cooling cutting fluid, and simulating the temperature field of actual processing, it is possible to guide on-site processing.

[0005] Therefore, there is an urgent need for a device that simulates laser-assisted processing to accurately obtain the thermal parameters in the laser-assisted processing process, meet the demand for accurate prediction of laser-assisted processing parameters, guide the adjustment of various instrument parameters in actual processing, optimize the cooling strategy, and ultimately improve processing efficiency and product quality. Summary of the invention

[0006] In order to solve the problems that laser energy cannot be effectively utilized and the workpiece surface processing quality cannot meet the requirements in laser-assisted processing, the present invention provides a thermal parameter measurement system and a measurement method for simulating laser-assisted processing, which simulates the temperature field of laser-assisted processing and provides a theoretical basis for parameter adjustment and equipment configuration in actual processing.

[0007] A thermal parameter measurement system for simulating laser-assisted processing includes a laser generator and a laser controller. The laser controller is connected to the laser generator through a circuit. A measuring device is arranged below the laser generator. One side of the measuring device is connected to a liquid cooling system for simulating the cooling of a workpiece during processing. The other side of the measuring device is connected to a temperature monitoring system for real-time monitoring of the temperature of the workpiece surface. The measuring device includes a heating system, a heat insulation module and a workpiece clamping module. The heating system includes a workbench, a heat-conducting copper plate, and a heater. The heat-conducting copper plate and the heater are sequentially arranged in the groove of the workbench from top to bottom, and two groups are symmetrically arranged. A workpiece is placed above the heat-conducting copper plate, and part of the workpiece is in contact with the surface of the workbench. The heater wire is coated with a heat-insulating material and connected to an external power supply. The thermal insulation module includes a thermal insulation acrylic plate and thermal insulation foam. Six thermal insulation acrylic plates are sequentially connected to form a rectangular frame. Thermal insulation foam is arranged in each thermal insulation acrylic plate. The laser generator passes through and is arranged on the upper thermal insulation module. The thermal insulation foam on one side is provided with an observation port and the thermal insulation foam on this side can be opened. The thermal insulation foam on the bottom is provided with a rectangular through hole. The workbench is placed in the rectangular through hole. The workpiece clamping module includes two symmetrically arranged workpiece pressure plates, the workpiece is placed between the workpiece pressure plates and the workbench, each of the workpiece pressure plates is positioned on the workbench by a cylindrical positioning column, the positioning column is fixed to the middle of one side of the workbench by a threaded connection, the positioning column sleeve is provided with a spring, and the spring is located between the workbench and the workpiece pressure plate; each workpiece pressure plate is clamped to the workbench by two groups of nuts and bolts, each group of nuts and bolts is symmetrically arranged at both ends of the positioning column, and aerogel I is arranged between each workpiece pressure plate and the workpiece.

[0008] Furthermore, the liquid supply cooling system consists of an air circuit module and a liquid circuit module. The air circuit module consists of an air compressor, an air tank, a pressure gauge II and a pressure reducing valve II connected in sequence. The liquid circuit module consists of a liquid storage tank, a gear oil pump, a pressure gauge I, a pressure reducing valve I and a one-way throttle valve connected in sequence, and a waste liquid cylinder and an overflow valve connected in parallel to a flow meter. The pressure reducing valve II of the air circuit module and the flow meter of the liquid circuit module are both connected to a sprayer.

[0009] Furthermore, the sprayer is connected to a nozzle through a pipeline, and the nozzle passes through one side of the insulation module and is placed above the workpiece.

[0010] Furthermore, the temperature monitoring system includes a thermocouple, a signal conditioning circuit, a data acquisition circuit, a PLC, a microcontroller, a storage unit and a host computer. The two thermocouples are symmetrically arranged in the center of both sides below the workpiece, and their output circuits pass through the workbench and the thermal insulation module in turn to transmit the collected signal to the signal conditioning circuit. The signal conditioning circuit filters and amplifies the collected signal to form a conditioned analog signal and transmits it to the data acquisition circuit. The analog-to-digital converter in the data acquisition circuit converts the conditioned analog signal into a digital signal and transmits it to the PLC. The PLC communicates bidirectionally with the microcontroller through a serial bus interface, transmits the digital signal to the microcontroller and processes it to form data. The microcontroller periodically stores the processed digital signal data in the storage unit through a serial peripheral interface, and transmits the data to the host computer through a USB interface. The host computer operates to receive and process the data sent by the microcontroller to construct a thermal parameter model.

[0011] A method for measuring thermal parameters of simulated laser-assisted processing, the steps of which are as follows: S1, placing the heater and the heat-conducting copper plate in the groove of the workbench in sequence, placing the workpiece on the heat-conducting copper plate, and arranging the two thermocouples under the workpiece; S2, evacuate the air in the measuring device to a vacuum, turn on the power switch of the heater, heat the thermally conductive copper plate, and the thermally conductive copper plate transfers heat to the workpiece through heat conduction. The two thermocouples sense the voltage due to the workpiece being heated, and through signal processing and conversion, they are connected to the host computer outside the device to obtain data on the change of the workpiece temperature over time; S3. To avoid too long heating time, the workpiece is preheated first, and the initial time when the temperature is constant is taken as the opening time of the nozzle. At this time, the heater switch is turned off, and the liquid supply cooling system switch is turned on at the same time, and the coolant is sprayed through the nozzle at a constant flow rate to perform convection cooling on the heated workpiece; S4, acquiring the data of the change of the workpiece temperature over time during the convection cooling from the host computer, and constructing a convection heat transfer coefficient model; S5. To avoid heat transfer, turn off the heater switch, take out the heat-conducting copper plate, and after the workpiece cools down, evacuate the air in the measuring device to a vacuum, take the initial time when the temperature is constant as the start time of the laser generator, turn on the laser controller switch, and perform constant-power radiation heating on the workpiece; S6, acquiring data on the change of the workpiece temperature over time during constant power radiation heating from the host computer, and constructing a laser absorption rate model; S7. Using the convection heat transfer coefficient model and the laser absorption rate model as thermal parameter models of the workpiece material to be processed in laser-assisted processing, performing three-dimensional simulation of laser-assisted processing in the host computer, and analyzing the temperature field distribution law.

[0012] Furthermore, the convective heat transfer coefficient model in step S4 is constructed as follows: in, and are the time for the two thermocouples to reach the same temperature, is the workpiece density, is the specific heat capacity of the workpiece, is the workpiece volume, is the convective heat transfer contact area between the coolant and the workpiece thin plate, is the convective heat transfer coefficient between the workpiece and the coolant.

[0013] Furthermore, the laser absorption rate model in step S6 is constructed as follows: in, is the laser radiation flux, is the laser radiation radius, is the radiation absorption power, is the laser absorption rate.

[0014] The beneficial effects of the present invention are as follows: The laser generator is responsible for generating a high-energy laser beam to provide the energy source required for processing. The laser controller adjusts the power and pulse frequency of the laser to ensure that the laser can achieve different heat inputs when processing different materials, thereby affecting the heating effect and processing quality of the workpiece.

[0015] The measuring device located below the laser generator is responsible for capturing and recording thermal parameters during laser processing. The device measures and captures the temperature of the workpiece through a temperature sensor, providing a basis for subsequent analysis. The design of the measuring device ensures that data can be captured in real time during the laser processing process, thereby providing a basis for evaluating the processing effect and optimizing the process parameters.

[0016] The liquid cooling system connected to one side of the measuring device simulates the state of the workpiece during the cooling process. This system simulates the temperature change of the workpiece during actual processing by outputting coolant to prevent overheating and deformation of the workpiece caused by laser heating. It ensures the stability of material properties in high temperature environment and controls the range of heat-affected zone, thereby improving the accuracy and quality of processing.

[0017] The temperature monitoring system connected to the other side of the measuring device is used to monitor the temperature of the workpiece surface in real time. Through the temperature sensor, the system can continuously track the temperature changes of the workpiece during laser processing, timely feedback the thermal state of the workpiece, and obtain the corresponding thermal parameters through calculation, providing real-time data support for process optimization during laser processing, reducing the risk of thermal damage during processing, and ensuring the stability and consistency of processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is an overall schematic diagram of the present invention; Figure 2 This is the schematic diagram of the liquid supply cooling system; Figure 3 This is a diagram of the liquid supply cooling system; Figure 4 is a schematic diagram of the measuring device; Figure 5 This is the structural block diagram of the temperature monitoring system; Figure 6 This is a schematic diagram of the workbench; Figure 7 This is the simulation diagram of the temperature field of laser-assisted processing; Figure 8 This is the workpiece temperature-time variation diagram.

[0019] The reference numerals are as follows: 4-gear oil pump, 5-liquid storage tank, 6-pressure gauge I, 7-waste liquid cylinder, 8-overflow valve, 9-pressure reducing valve I, 10-one-way throttle valve, 11-flow meter, 12-sprayer, 13-laser controller, 14-data acquisition circuit, 15-host computer, 17-signal conditioning circuit, 19-thermal insulation acrylic plate, 23-laser generator, 25-pressure reducing valve II, 26-pressure gauge II, 27-gas tank, 28-air compressor, 29-nozzle, 30-thermal insulation foam, 31-positioning column, 32-workpiece pressure plate, 33-aerogel I, 34-spring, 35-workbench, 36-workpiece, 37-thermal conductive copper plate, 38-heater, 40-thermocouple, 42-nut, 43-bolt. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments: like Figure 1-Figure 6 As shown, a thermal parameter measurement system for simulating laser-assisted processing is provided, including a laser generator 23 and a laser controller 13 . The laser controller 13 is connected to the laser generator 23 through a circuit, and a measuring device is arranged below the laser generator 23 .

[0021] The measuring device includes a heating system, a heat-insulating module and a workpiece clamping module. The heating system includes a workbench 35, a heat-conducting copper plate 37 and a heater 38. The heat-conducting copper plate 37 and the heater 38 are arranged in the groove of the workbench 35 from top to bottom, and two groups are symmetrically arranged. A workpiece 36 is placed above the heat-conducting copper plate 37, and part of the workpiece 36 is in contact with the surface of the workbench 35. The lead of the heater 38 is coated with a heat-insulating material and connected to an external power supply. The heat-insulating module includes a heat-insulating acrylic plate 19 and a heat-insulating foam 30. Six heat-insulating acrylic plates 19 are connected in sequence to form a rectangular frame. Heat-insulating foam 30 is arranged in each heat-insulating acrylic plate 19. The laser generator 23 passes through and is arranged on the upper heat-insulating module. The rear heat-insulating foam 30 is provided with an observation port, and the heat-insulating foam 30 can be opened to facilitate the observation and control of experimental phenomena and the work. The workpiece 36 is placed in the workbench 35, and a rectangular through hole is set in the bottom insulation foam 30. The workbench 35 is placed in the rectangular through hole. The workpiece clamping module includes two symmetrically arranged workpiece pressure plates 32. The workpiece 36 is placed between the workpiece pressure plate 32 and the workbench 35. Each workpiece pressure plate 32 is positioned on the workbench 35 by a cylindrical positioning column 31. The positioning column 31 is fixed to the middle of one side of the workbench 35 by a threaded connection. The positioning column 31 is sleeved with a spring 34, and the spring 34 is located between the workbench 35 and the workpiece pressure plate 32; each workpiece pressure plate 32 is clamped to the workbench 35 by two sets of nuts 42 and bolts 43. Each set of nuts 42 and bolts 43 are symmetrically arranged at both ends of the positioning column 31. Aerogel I33 is set between each workpiece pressure plate 32 and the workpiece 36 to minimize the heat exchange between the workpiece and the clamping module during the experiment.

[0022] The workbench 35 is placed at the bottom of the measuring device, with two symmetrical square notches on the top. Two heaters 38 and two heat-conducting copper plates 37 are stacked in sequence in the notches, and the middle part is cut off for arranging the thermocouple 40. The workpiece 36 is placed on the heat-conducting copper plate 37. When placing, ensure that the workpiece 36 is in contact with the heat-conducting copper plate 37, and the edge of the workpiece and its middle part are in contact with the upper surface of the workbench 35 (thermal insulation aerogel can be placed between the two here). The setting of the workbench 35 can stably support the measuring device and have a good insulation effect.

[0023] A hole is opened at the lower left side of the measuring device. The hole will be used for the passage of the heater 38 circuit and the thermocouple 40 output circuit and will be connected to the external circuit. All openings and contact parts with other components are sealed with silicone rubber to ensure the sealing and heat insulation performance of the device.

[0024] The right side of the measuring device is connected to a liquid supply cooling system for simulating the workpiece in cooling processing; the liquid supply cooling system consists of an air circuit module and a liquid circuit module, the air circuit module is composed of an air compressor 28, an air tank 27, a pressure gauge II26 and a pressure reducing valve II25 connected in sequence, the liquid circuit module is composed of a liquid storage tank 5, a gear oil pump 4, a pressure gauge I6, a pressure reducing valve I9 ​​and a one-way throttle valve 10 connected in sequence, and a waste liquid cylinder 7 and an overflow valve 8 connected in parallel to a flow meter 11, the pressure reducing valve II25 of the air circuit module and the flow meter 11 of the liquid circuit module are both connected to a sprayer 12, the sprayer 12 is connected to a nozzle 29 through a pipeline, and the nozzle 29 passes through a side insulation module and is placed above the workpiece.

[0025] During operation, the air compressor 28 generates compressed air and stores it in the gas tank 27. The compressed air in the gas tank 27 monitors the air pressure through the pressure gauge II26. After ensuring that the system operates within a safe range, the compressed air passes through the pressure reducing valve II25, is adjusted to an appropriate pressure, and then enters the sprayer 12 to provide atomization power for the spray system; the coolant in the liquid storage tank 5 passes through the gear oil pump 4, and the pressurized coolant monitors the pressure through the pressure gauge I6 to ensure that it is within the set range. The coolant is adjusted to an appropriate pressure through the pressure reducing valve I9, and then enters the flow meter 11 after adjusting the flow through the one-way throttle valve 10, bypassing the parallel overflow valve 8 and the waste liquid cylinder 7, performing the unloading function, preventing the system from overloading, and ensuring the efficient and stable operation of the system. The flow meter 11 monitors and controls the coolant flow in real time, and then the coolant enters the sprayer 12.

[0026] After the gas circuit module and the liquid circuit module are connected to the sprayer 12, the coolant enters the liquid injection channel joint of the nozzle 29 through the liquid pipeline, and the high-pressure gas enters the gas injection channel joint of the nozzle 29 from the gas pipeline. The high-pressure gas enters the mixing chamber through the vent hole in the gas injection channel joint of the nozzle 29, where it is fully mixed with the coolant from the liquid injection channel joint. Then, the mixed gas droplets are further accelerated through the acceleration chamber and enter the vortex chamber. In the vortex chamber, the high-pressure gas and coolant are further mixed and accelerated, and finally sprayed to the workpiece 36 through the nozzle 29 in the form of atomized droplets.

[0027] The left side of the measuring device is connected to a temperature monitoring system for real-time monitoring of the temperature of the workpiece surface. The temperature monitoring system includes a thermocouple 40, a signal conditioning circuit 17, a data acquisition circuit 14, a PLC, a microcontroller, a storage unit and a host computer 15 (PLC, microcontroller and storage unit 3 devices) Figure 1Omitted). Two thermocouples 40 are symmetrically arranged at the center of both sides below the workpiece 36, and their output circuits sequentially pass through the workbench 35 and the heat insulation module to transmit the collected signals to the signal conditioning circuit 17 to improve the quality and stability of the signal. The signal conditioning circuit 17 filters and amplifies the collected signals to form a conditioned analog signal and transmits it to the data acquisition circuit 14. The analog-to-digital converter in the data acquisition circuit 14 converts the conditioned analog signal into a digital signal and transmits it to the PLC. The function of the PLC is to perform preliminary processing on the digital signal, including signal screening and preliminary analysis. The PLC communicates bidirectionally with the microcontroller through a serial bus interface, transmits the digital signal to the microcontroller and processes it to form data. The processing process includes data packaging and temperature unit conversion to ensure that the data format and unit meet the system requirements. The microcontroller regularly stores the processed digital signal data in the storage unit through the serial peripheral interface. The storage unit is used to store historical temperature data for a long time, which is convenient for subsequent data analysis and recording. The data is transmitted to the host computer 15 through the USB interface, and the host computer 15 operates to receive and process the data sent by the microcontroller and calculate the thermal parameters.

[0028] Embodiment 1: The present embodiment provides a method for measuring the convective heat transfer coefficient of a coolant. First, a heater 38 and a heat-conducting copper plate 37 are placed in a groove of a workbench 35 in sequence, and then a workpiece 36 is placed on the heat-conducting copper plate 37. Two thermocouples 40 are arranged below the workpiece 36. Then, the air in the measuring device is evacuated to a vacuum to avoid heat conduction and heat convection between the workpiece and the air in the device. At this time, the power switch of the heater is turned on to heat the heat-conducting copper plate 37. The heat-conducting copper plate 37 then transfers heat to the workpiece 36 through heat conduction. The two thermocouples 40 sense voltage due to the heating of the workpiece 36. Through signal processing and conversion, they are connected to a host computer 15 outside the device to obtain data on the change of the workpiece temperature over time. To avoid too long a heating time, the workpiece 36 is preheated first, and data is obtained according to the thermocouple 40. The initial time when the temperature is constant is taken as the opening time of the nozzle 29. At this time, the switch of the heater 38 is turned off, and the switch of the liquid supply cooling system is turned on at the same time. The cooling liquid is sprayed at a constant flow rate through the nozzle in the device to perform convective cooling on the heated workpiece. In this process, it can be known from the energy conservation of the workpiece that: in, is the energy entering the workpiece, is the energy leaving the workpiece, As internal heat source, is the energy stored in the workpiece; For solid workpieces, specific heat capacity at constant pressure Specific heat capacity at constant volume The same, you know, in, is the workpiece density, is the specific heat capacity of the workpiece, is the workpiece volume, is the workpiece temperature, It is the coolant heat exchange time; During the cooling process, is 0, ignoring the heat source in the system, Energy leaving the workpiece At this time, it is the convection heat exchange between the coolant and the workpiece. According to Newton's cooling formula, in, is the convective heat transfer coefficient to be measured, is the convective heat transfer contact area between the coolant and the workpiece thin plate, is the workpiece surface temperature, is the temperature of heat exchange medium; Substituting equation (82) and equation (84) into equation (83), we obtain: Due to the high thermal conductivity of the workpiece, the temperature of the workpiece is consistent everywhere. The distribution is only the coolant heat exchange time function, so For thin plate workpieces, ignoring the convection heat transfer in the thickness direction, , is the side length of the workpiece, and the temperature of the heat transfer medium is is the initial temperature of the coolant, and the stable initial temperature of the workpiece is measured and initial coolant temperature , take the mean is the reference temperature, find out the specific heat capacity of the workpiece at the reference temperature ,density , Simplifying formula (86), we can obtain Integrate at both ends, Transformed to get, When the coolant heat exchange time achieve Substituting into formula (89), we get: Through the upper computer (15) connected by the thermocouple, the discrete point data of the temperature change of the two thermocouples over time are obtained, and two curves are obtained by fitting, which are respectively recorded as , , When the temperature When the temperature of the two thermocouples is , ,make , , respectively solve for the heat transfer coefficient , , take the average As the convection heat transfer coefficient between the workpiece and the coolant, .

[0029] Embodiment 2: This embodiment provides a method for measuring laser absorption rate. To avoid heat transfer, the heater 38 is turned off, the heat-conducting copper plate 37 is taken out, and the air in the measuring device is evacuated to a vacuum to avoid heat conduction and heat convection between the workpiece and the air in the device. The initial time when the temperature is constant is taken as the start time of the laser generator 23, and the laser controller 13 is turned on to perform constant-power radiation heating on the workpiece 36. During radiation heating, the energy entering the workpiece is only the radiation absorption power , so = 0, ignoring the internal heat source, according to formula (81), ,Right now For thin plate workpieces with high thermal conductivity, the thermal resistance inside the system workpiece is negligible, and the temperature of the workpiece is consistent after radiation. The temperature distribution is a function of time, that is, Simplifying and integrating, we get Right now Through the upper computer (15) connected by the thermocouple, the discrete point data of the temperature change of the two thermocouples over time are obtained, and two curves are obtained by fitting, which are respectively recorded as , , Take reference temperature , , find out the specific heat capacity of the workpiece at the reference temperature ,density , , The curves are , The corresponding time Substituting the temperature under into equation (94), The radiation absorption power of the workpiece in the time period 0-t is obtained as follows: , , take the average As the actual radiation absorption power of the workpiece, according to the definition, in, is the laser radiation radius, is the radiation flux absorbed by the workpiece system, Therefore, the laser absorption rate is in, is the laser radiation flux, As the radiation time increases, the workpiece temperature rises and the material absorption rate also changes continuously. Simplifying equation (94), The two thermocouples are connected to the host computer (15) through signal processing and conversion, and the acquired temperature-time data points are exported. The time at each point is substituted into formula (97) by the computer for calculation to obtain the absorption rate at each moment, and each time is replaced with the corresponding temperature point to obtain the variation diagram of the radiation power at the discrete point with the temperature. Substitute it into formula (96) and perform data fitting by the computer to obtain the variation curve expression of the laser absorption rate with the temperature: .

[0030] Embodiment 3: Based on Example 1 and Example 2, this example provides a method for predicting the temperature field of laser-assisted processing, and the heat transfer coefficient obtained above is , laser absorption rate As the thermal parameters of the workpiece material to be processed in laser-assisted processing, they are input into the COMLSOL Multiphysics simulation software through the host computer 15, and a three-dimensional simulation model of laser-assisted processing is constructed to calculate and analyze the temperature field distribution law. The simulation results are used to show the change of the workpiece surface temperature. In order to obtain the ideal processing temperature, the calculated laser absorptivity and heat transfer coefficient can be used to effectively control the heat input and cooling effect during the processing by adjusting the laser radiation power and the flow rate of the cooling nozzle.

[0031] When the laser approaches the center of the rotating cylindrical workpiece surface, the surface heat accumulates due to the reduction of linear speed, resulting in increased thermal damage to the tool, which significantly shortens the tool life. In order to solve this problem, an adaptive laser power control strategy was introduced. During the processing, based on the position change of the tool, a PID control model was introduced in the simulation software to achieve real-time adjustment of the laser power, ensure that the workpiece surface maintains an ideal stable heating temperature, and avoid thermal damage to the tool caused by speed reduction.

[0032] like Figure 7 and Figure 8 As shown, to achieve a stable processing temperature of 300K ( Figure 7 The white dotted box in the middle is the laser irradiation area). The radiation power can be adjusted to 14.2W and the coolant flow rate can be set to 0.5L / min. Through this parameter setting, the expected temperature field can be achieved and the processing performance can be optimized.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A thermal parameter measurement system for simulating laser-assisted processing, comprising a laser generator (23) and a laser controller (13), characterized in that: The laser controller (13) is connected to the laser generator (23) via a circuit. A measuring device is provided below the laser generator (23). One side of the measuring device is connected to a liquid cooling system for simulating the cooling of a workpiece during processing. The other side of the measuring device is connected to a temperature monitoring system for real-time monitoring of the temperature of the workpiece surface. The measuring device includes a heating system, a heat insulation module and a workpiece clamping module. The heating system comprises a workbench (35), a heat-conducting copper plate (37), and a heater (38). The heat-conducting copper plate (37) and the heater (38) are sequentially arranged in a groove of the workbench (35) from top to bottom, and two groups are symmetrically arranged. A workpiece (36) is placed above the heat-conducting copper plate (37), and a portion of the workpiece (36) is in contact with the surface of the workbench (35). The wire of the heater (38) is coated with a heat-insulating material and is connected to an external power source. The thermal insulation module comprises a thermal insulation acrylic plate (19) and thermal insulation foam (30), six thermal insulation acrylic plates (19) are sequentially connected to form a rectangular frame, thermal insulation foam (30) is arranged in each of the thermal insulation acrylic plates (19), the laser generator (23) passes through and is arranged on the upper thermal insulation module, the thermal insulation foam (30) on one side is provided with an observation port and the thermal insulation foam (30) on this side can be opened, the thermal insulation foam (30) on the bottom is provided with a rectangular through hole, and the workbench (35) is placed in the rectangular through hole, The workpiece clamping module comprises two symmetrically arranged workpiece pressing plates (32), the workpiece (36) is placed between the workpiece pressing plates (32) and the workbench (35), each of the workpiece pressing plates (32) is positioned on the workbench (35) by a cylindrical positioning column (31), the positioning column (31) is fixed to the middle of one side of the workbench (35) by a threaded connection, the positioning column (31) is sleeved with a spring (34), and the spring (34) is located between the workbench (35) and the workpiece pressing plate (32); each of the workpiece pressing plates (32) is clamped to the workbench (35) by two groups of nuts (42) and bolts (43), each group of nuts (42) and bolts (43) is symmetrically arranged at both ends of the positioning column (31), and an aerogel I (33) is arranged between each of the workpiece pressing plates (32) and the workpiece (36).

2. A thermal parameter measurement system for simulating laser-assisted processing according to claim 1, characterized in that: The liquid supply cooling system is composed of an air circuit module and a liquid circuit module. The air circuit module is composed of an air compressor (28), an air tank (27), a pressure gauge II (26) and a pressure reducing valve II (25) connected in sequence. The liquid circuit module is composed of a liquid storage tank (5), a gear oil pump (4), a pressure gauge I (6), a pressure reducing valve I (9) and a one-way throttle valve (10) connected in sequence, and a waste liquid cylinder (7) and an overflow valve (8) connected in parallel to a flow meter (11). The pressure reducing valve II (25) of the air circuit module and the flow meter (11) of the liquid circuit module are both connected to a sprayer (12).

3. A thermal parameter measurement system for simulating laser-assisted processing according to claim 2, characterized in that: The sprayer (12) is connected to a nozzle (29) via a pipe, and the nozzle (29) is placed above the workpiece through one side of the insulation module.

4. A thermal parameter measurement system for simulating laser-assisted processing according to claim 3, characterized in that: The temperature monitoring system comprises a thermocouple (40), a signal conditioning circuit (17), a data acquisition circuit (14), a PLC, a microcontroller, a storage unit and a host computer (15). The two thermocouples (40) are symmetrically arranged at the center of both sides below the workpiece (36). The output circuit of the thermocouples (40) sequentially passes through the workbench (35) and the heat insulation module to transmit the collected signal to the signal conditioning circuit (17). The signal conditioning circuit (17) filters and amplifies the collected signal to form a conditioned analog signal and transmits it to the data acquisition circuit (14). The analog-to-digital converter in the data acquisition circuit (14) converts the conditioned analog signal into a digital signal and transmits it to the PLC. The PLC performs bidirectional communication with the microcontroller via a serial bus interface, transmits the digital signal to the microcontroller and processes it to form data. The microcontroller periodically stores the processed digital signal data in the storage unit via a serial peripheral interface, and transmits the data to the host computer (15) via a USB interface. The host computer (15) receives and processes the data sent by the microcontroller to construct a thermal parameter model.

5. A method for measuring thermal parameters for simulating laser-assisted processing, characterized in that: The thermal parameter measurement system for simulating laser-assisted processing as claimed in claim 4 is used for measurement, and the steps are as follows: S1, placing the heater (38) and the heat-conducting copper plate (37) in the groove of the workbench (35) in sequence, placing the workpiece (36) on the heat-conducting copper plate (37), and arranging the two thermocouples (40) below the workpiece (36); S2, evacuating the air in the measuring device to a vacuum, turning on the power switch of the heater (38), heating the heat-conducting copper plate (37), and transferring heat to the workpiece (36) by heat conduction. The two thermocouples (40) sense voltage due to the workpiece (36) being heated, and are connected to the host computer (15) outside the device through signal processing and conversion, so as to obtain data on the change of the workpiece temperature over time; S3, in order to avoid the heating time being too long, the workpiece (36) is preheated first, and the initial time when the temperature is constant is taken as the opening time of the nozzle (29), at which time the switch of the heater (38) is turned off, and the switch of the liquid supply cooling system is turned on, and the cooling liquid is sprayed at a constant flow rate through the nozzle (29) to perform convection cooling on the heated workpiece (36); S4, acquiring data on the change in temperature of the workpiece (36) over time during convection cooling from the host computer (15), and constructing a convection heat transfer coefficient model; S5. To avoid heat transfer, turn off the switch of the heater (38), remove the heat-conducting copper plate (37), and after the workpiece (36) cools down, evacuate the air in the measuring device to a vacuum, take the initial time when the temperature is constant as the start time of the laser generator (23), turn on the switch of the laser controller (13), and perform constant-power radiation heating on the workpiece (36); S6, acquiring data on the change in temperature of the workpiece (36) over time during constant power radiation heating from the host computer (15), and constructing a laser absorption rate model; S7. Using the convection heat transfer coefficient model and the laser absorption rate model as thermal parameter models of the workpiece material to be processed in laser-assisted processing, performing three-dimensional simulation of laser-assisted processing in the host computer (15), and analyzing the temperature field distribution law.

6. The method for measuring thermal parameters of simulated laser-assisted processing according to claim 5, characterized in that: The convective heat transfer coefficient model in step S4 is constructed as follows: in, and are the time for the two thermocouples to reach the same temperature, is the workpiece density, is the specific heat capacity of the workpiece, is the workpiece volume, is the convective heat transfer contact area between the coolant and the workpiece sheet, is the convective heat transfer coefficient between the workpiece and the coolant.

7. A thermal parameter measurement method for simulating laser-assisted processing according to claim 6, characterized in that: The laser absorption rate model in step S6 is constructed as follows: in, is the laser radiation flux, is the laser radiation radius, is the radiation absorption power, is the laser absorption rate.

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