Temperature measurement system and temperature measurement method

Abstract

A temperature measurement system 100 according to the present disclosure comprises: an infrared camera 10 that generates an infrared image of the surface of an object 16; a simulation device 12 that simulates a change in the surface temperature of the object 16 and a change in the internal temperature of the object 16; and a storage device 14 that stores simulation conditions. The surface temperature and internal temperature of the object 16 are output on the basis of the infrared image and a simulation result obtained by the simulation device 12. The storage device 14 stores data relating to the surface temperature detected when the object 16 is processed in a manner that is associated with a phase change, and data relating to the internal state of the object 16 detected by X-rays when the object 16 is processed in a manner that is associated with a phase change.

Description

Thermometer Measurement System and Thermometer Measurement Method

[0001] The present disclosure relates to a thermometer measurement system and a thermometer measurement method.

[0002] Conventionally, a technique for joining two members by laser welding is known.

[0003] Patent Document 1 discloses non-contact measurement of the surface temperature of a welded portion using an infrared camera in order to evaluate the quality of the welded portion by laser welding.

[0004] Japanese Patent Application Laid-Open No. 2001-191186

[0005] Yosuke Kawato, "Numerical Analysis of Keyhole Reduction in Laser Welding", Journal of the Welding Society, 2017, Vol. 86, No. 1, pp. 38-p41

[0006] In order to improve the accuracy of laser welding, it is effective to grasp the temperature of the workpiece during welding and its change. Information on the temperature of the workpiece and its change can be useful information when determining welding conditions such as the output of the laser beam, the irradiation time of the laser beam, and the spot diameter of the laser beam. Examples of the temperature of the workpiece include the surface temperature and the internal temperature of the welded portion.

[0007] As described in Patent Document 1, it is possible to measure the surface temperature of the welded portion in real time and non-contact. On the other hand, it is difficult to measure the internal temperature of the welded portion in real time and non-contact. Examples of means for knowing the internal temperature of the welded portion include computer simulation.

[0008] However, there is almost no technique for confirming the consistency between the internal temperature obtained by computer simulation and the actual internal temperature. Since the consistency between the internal temperature calculated by simulation and the actual internal temperature cannot be confirmed, it is difficult to optimize the simulation conditions to improve the accuracy of the simulation.

[0009] An object of the present disclosure is to improve the accuracy of simulation and obtain information regarding the internal temperature of an object.

[0010] This disclosure provides a temperature measurement system comprising: an infrared camera that generates an infrared image of the surface of an object; a simulation device that simulates changes in the surface temperature and internal temperature of the object; and a storage device that stores simulation conditions. Based on the infrared image and the simulation results from the simulation device, the surface temperature and internal temperature of the object are output, and the storage device stores data relating to the surface temperature detected when the object was processed to involve a phase change, and data relating to the internal state of the object detected by X-rays when the object was processed to involve a phase change.

[0011] The technology described herein allows for improved simulation accuracy and the acquisition of information regarding the internal temperature of an object.

[0012] Figure 1 is a diagram showing the configuration of a temperature measurement system according to the present disclosure. Figure 2 is a diagram showing the configuration of preparation equipment for adjusting the simulation conditions in the simulation device. Figure 3 is a flowchart showing the preparation process for adjusting the simulation conditions in the simulation device.

[0013] (Knowledge forming the basis of this disclosure) The inventors have diligently studied means for determining the internal temperature of an object. As a result, they focused on detecting the internal state of an object using X-rays. An example of the internal state of an object is the flow velocity of a molten material. The simulation device can simulate changes in the surface temperature of an object and changes in the internal state of the object. Therefore, if the simulation results are consistent with the surface temperature detection results using an infrared camera and the internal state detection results using X-rays, it can be inferred that the simulation results for the internal temperature are consistent with the actual internal temperature.

[0014] The embodiments of this disclosure will be described below with reference to the drawings. This disclosure is not limited to the embodiments described below.

[0015] (Embodiment) Figure 1 is a configuration diagram of a temperature measurement system according to an embodiment of the present disclosure. The temperature measurement system 100 includes an infrared camera 10, a simulation device 12, and a storage device 14. The temperature measurement system 100 measures the surface temperature and internal temperature of the object 16.

[0016] The object 16 is subjected to processing that involves a phase change from a solid state to a liquid state, and a phase change from a liquid state to a solid state. The surface temperature and internal temperature of the object 16 are measured in a time series from the start to the end of the processing. The surface temperature is an actual value measured by an infrared camera 10. The internal temperature is a calculated value by a simulation device 12. The surface temperature may also be a calculated value by the simulation device 12.

[0017] The surface temperature is the surface temperature of the processed portion (welded portion) of the object 16. More specifically, the surface temperature is the temperature distribution on the surface of the object 16. The internal temperature is the internal temperature of the processed portion (welded portion) of the object 16. More specifically, the internal temperature is the temperature distribution inside the object 16.

[0018] The object 16 is, for example, a workpiece to be laser-welded. The precise temperature of the workpiece and its change over time can be valuable information when setting various parameters related to laser welding, such as the intensity of the laser light, the irradiation time of the laser light, and the spot diameter of the laser light. The workpiece may be made of metal or resin.

[0019] The infrared camera 10 captures the surface of the object 16 and generates an infrared image. The infrared camera 10 may be configured to continuously capture the surface of the object 16 and generate multiple infrared images. In other words, the infrared camera 10 can capture a video of the surface of the object 16 at a predetermined frame rate.

[0020] The simulation device 12 simulates, for example, changes in the surface temperature, internal temperature, and internal flow velocity of the welded area in laser welding, and outputs the results. The internal flow velocity is the flow velocity of the molten material inside the object 16. The simulation device 12 can be a commercially available simulator such as FLOW-3D (Flow Science), Ansys Fluids (Ansys), or STAR-CCM+ (Siemens Digital Industries Software).

[0021] The memory device 14 stores the simulation conditions. The simulation conditions are the conditions that should be given to the simulation device 12 when executing the simulation. Examples of simulation conditions include the density of the material, the viscosity of the material, the pressure of the material, the velocity of the material, the temperature of the material, the flow rate of the material, the output of the laser light, the wavelength of the laser light, the irradiation radius of the laser light, the time step size at the start of the calculation, and the end time of the calculation. By optimizing the simulation conditions, the accuracy of the simulation can be improved.

[0022] In this embodiment, the storage device 14 stores optimized simulation conditions. By performing a simulation using the simulation conditions stored in the storage device 14, the accuracy of the simulation can be improved. Optimized simulation conditions can be created in a preparation step described later.

[0023] The memory device 14 also stores data relating to the surface temperature detected when the object 16 was processed to undergo a phase change, and data relating to the internal state of the object 16 detected by X-rays when the object was processed to undergo a phase change. The data relating to the internal state is, for example, data relating to the flow velocity of the material constituting the object 16 in its molten state. Other data relating to the internal state includes data relating to the pressure of the material constituting the object 16 in its molten state. This data may be the data used to optimize the simulation conditions.

[0024] The simulation device 12 and the storage device 14 each constitute part of the computer 18. The simulation device 12 may be simulation software installed on the computer 18. The storage device 14 may be the memory or storage of the computer 18.

[0025] Computer 18 may be an edge computer or a cloud computer. If computer 18 is a cloud computer, the functions of the simulation device 12 and the storage device 14 may be provided by multiple computers connected via a communication network such as the Internet.

[0026] In this embodiment, the surface temperature and internal temperature of the object 16 may be output based on the infrared image from the infrared camera 10 and the simulation results from the simulation device 12. The temperature measurement system 100 may be equipped with an interface 20 for outputting the surface temperature and internal temperature to the outside. The interface 20 is, for example, a display. In this case, the surface temperature and internal temperature are output in the form of an image, such as a two-dimensional heat map. The two-dimensional heat map may be created from data in CSV format. The interface 20 may also be a bus for extracting the measured surface temperature and internal temperature data to the outside.

[0027] (Preparation Process) Figure 2 is a diagram showing the configuration of the preparation equipment 200 for adjusting the simulation conditions in the simulation device 12. The preparation equipment 200 includes an infrared camera 22, an X-ray inspection machine 24, and a storage device 26.

[0028] The infrared camera 22 captures the surface of the object 16 and generates an infrared image. The infrared camera 22 can also function as the infrared camera 10 described with reference to Figure 1. Therefore, the infrared camera 22 has the same functions as the infrared camera 10. However, the infrared camera 22 may be a camera dedicated to the preparation equipment 200.

[0029] The X-ray inspection machine 24 detects the internal state of the object 16. More specifically, the X-ray inspection machine 24 photographs the inside of the object 16 and generates an X-ray fluoroscopic image. The X-ray inspection machine 24 may continuously photograph the inside of the object 16 and generate multiple X-ray fluoroscopic images. In other words, the X-ray inspection machine 24 can capture a video of the inside of the object 16 at a predetermined frame rate.

[0030] The frame rate of the X-ray inspection machine 24 may match or differ from the frame rate of the infrared camera 22.

[0031] The internal state of the object 16 can be detected from the X-ray fluoroscopic image obtained by the X-ray inspection machine 24. The internal state is, for example, the flow velocity of the molten material constituting the object 16. It is possible to calculate the flow velocity of the molten material from multiple time-series X-ray fluoroscopic images (Non-Patent Literature 1). The flow velocity may be the flow velocity at any position, or it may be the average flow velocity. Alternatively, the distribution of the flow velocity of the molten material may be calculated.

[0032] The flow velocity inside object 16 is closely related to the internal temperature of object 16. Therefore, if the measured internal flow velocity matches the simulated internal flow velocity well, it can be inferred that the accuracy of the internal temperature calculated by the simulation is high.

[0033] The storage device 26 stores infrared images from the infrared camera 22 and X-ray fluoroscopic images from the X-ray inspection machine 24. The storage device 26 may be the memory or storage of a computer.

[0034] The storage device 26 can also serve as the storage device 14 as described with reference to Figure 1. Therefore, the storage device 26 has the same functions as the storage device 14. However, the storage device 26 may be a storage device dedicated to the preparation equipment 200.

[0035] The preparation equipment 200 may include the simulation device 12 described with reference to Figure 1. The storage device 26 stores the simulation results of the surface temperature and internal state of the object 16 performed by the simulation device 12. Examples of simulation results of the internal state of the object 16 include the internal temperature and the internal flow velocity.

[0036] Figure 3 is a flowchart showing the preparation steps for adjusting the simulation conditions in the simulation device 12. The preparation steps are performed using the preparation equipment 200.

[0037] In step S1, the surface temperature and internal flow velocity are detected while processing the object 16 under arbitrary processing conditions that involve a phase change. Specifically, the surface temperature of the object 16 is detected by an infrared camera 22 while the object 16 is laser-welded under arbitrary welding conditions, and the internal state of the object 16 is detected by an X-ray inspection machine 24. In this embodiment, the infrared camera 22 continuously photographs the surface of the object 16. This creates multiple infrared images in a time series. Similarly, the X-ray inspection machine 24 continuously photographs the inside of the object 16. This creates multiple X-ray fluoroscopic images in a time series. The infrared images and X-ray fluoroscopic images are stored in the storage device 26.

[0038] The internal flow velocity can be calculated, for example, from multiple X-ray fluoroscopic images in a computer that constitutes the storage device 26.

[0039] In step S2, the changes in surface temperature, internal temperature, and internal flow velocity are calculated by simulation. The simulation conditions in step S2 can be set to simulate the laser welding in step S1. The simulation device 12 calculates the surface temperature, internal temperature, and internal flow velocity at any given time after irradiation with laser light. These simulation results are stored in the storage device 26.

[0040] Steps S1 and S2 are independent steps. Therefore, the order of steps S1 and S2 is not particularly limited.

[0041] In step S3, the actually measured detection results are compared with the simulation results. Specifically, the actually measured surface temperature at an arbitrary timing after the laser light irradiation is compared with the surface temperature obtained by simulation. Similarly, the actually measured internal flow velocity at an arbitrary timing after the laser light irradiation is compared with the internal flow velocity obtained by simulation.

[0042] In step S4, it is determined whether or not the actually measured surface temperature and internal flow velocity match the surface temperature and internal flow velocity obtained by simulation. For example, when the maximum surface temperature and the maximum internal flow velocity obtained by simulation at an arbitrary timing after the laser light irradiation are sufficiently close to the actually measured maximum surface temperature and the maximum internal flow velocity, it is determined that these surface temperature and internal flow velocity match. When the maximum surface temperature obtained by simulation is within a predetermined ratio (for example, 90% to 110%) of the actually measured maximum surface temperature, it can be determined that the surface temperature matches. Similarly, when the maximum internal flow velocity obtained by simulation is within a predetermined ratio (for example, 90% to 110%) of the actually measured maximum internal flow velocity, it can be determined that the internal flow velocity matches.

[0043] When the surface temperature and the internal flow velocity obtained by simulation do not match the actually measured surface temperature and the internal flow velocity, in step S5, the simulation conditions are changed. Specifically, the density of the material, the viscosity of the material, the pressure of the material, the velocity of the material, the temperature of the material, the flow rate of the material, the output of the laser light, the wavelength of the laser light, the irradiation radius of the laser light, the time step width at the start of the calculation, the end time of the calculation, etc. are changed. The process of changing the simulation conditions may be performed by a computer constituting the storage device 26, or may be performed by an operator operating the preparation equipment 200. The changed simulation conditions are stored in, for example, the storage device 26.

[0044] After the process of step S5, the processes of steps S2 to S4 are repeated until the surface temperature and the internal flow velocity obtained by simulation match the actually measured surface temperature and the internal flow velocity. Thereby, the simulation conditions most suitable for the actual laser welding are obtained.

[0045] The finally obtained simulation conditions are stored in the storage device 14 and / or the storage device 26 in association with the conditions of laser welding.

[0046] (Measurement step) After adjusting the simulation conditions, the surface temperature and the internal temperature of the object 16 during laser welding are measured using the temperature measurement system 100 shown in FIG. 1. The surface temperature of the object 16 is the measured value by the infrared camera 10. The simulation device 12 simulates the change in the surface temperature and the change in the internal temperature under the simulation conditions stored in the storage device 14. According to the method of the present embodiment, it is possible to measure the internal temperature of the object 16, which is difficult to measure directly, with sufficient accuracy.

[0047] Based on the infrared image by the infrared camera 10 and the simulation result by the simulation device 12, the surface temperature and the internal temperature of the object 16 are output.

[0048] (Other embodiments) (Supplementary note) From the description of the above embodiments, the following technologies are disclosed.

[0049] (Technology 1) An infrared camera that generates an infrared image of the surface of an object, a simulation device that simulates the change in the surface temperature and the change in the internal temperature of the object, a storage device that stores simulation conditions, and based on the infrared image and the simulation result by the simulation device, the surface temperature and the internal temperature of the object are output, and the storage device stores data related to the surface temperature detected when the object is processed with a phase change and data related to the internal state of the object detected by X-rays when the object is processed with a phase change. A temperature measurement system.

[0050] (Technology 2) The temperature measurement system according to Technology 1, wherein the data related to the internal state includes data related to the flow rate in the molten state of the material constituting the object.

[0051] (Technical 3) A temperature measurement method comprising: adjusting the simulation conditions in a simulation device that simulates changes in surface temperature and internal temperature of an object being processed to undergo a phase change; and after adjusting the simulation conditions, simulating the changes in surface temperature and internal temperature using the simulation device, wherein adjusting the simulation conditions includes detecting the surface temperature of the object with an infrared camera while processing the object to undergo the phase change; detecting the internal state of the object with an X-ray inspection machine while processing the object to undergo the phase change; and adjusting the simulation conditions using the detection results from the infrared camera and the detection results from the X-ray inspection machine.

[0052] (Technical 4) The temperature measurement method according to Technical 3, wherein the internal state includes the flow velocity of the material constituting the object in a molten state.

[0053] According to the technology described herein, the accuracy of predicting the internal temperature of an object being processed can be improved.

[0054] The technology disclosed herein is useful for processing where it is difficult to determine the internal temperature of the object. In particular, the technology disclosed herein is useful for simulating laser welding.

Claims

1. A temperature measurement system comprising: an infrared camera that generates an infrared image of the surface of an object; a simulation device that simulates changes in the surface temperature and internal temperature of the object; and a storage device that stores simulation conditions, wherein the surface temperature and internal temperature of the object are output based on the infrared image and the simulation results from the simulation device, and the storage device stores data relating to the surface temperature detected when the object was processed to involve a phase change, and data relating to the internal state of the object detected by X-rays when the object was processed to involve a phase change.

2. The temperature measurement system according to claim 1, wherein the data relating to the internal state includes data relating to the flow velocity of the material constituting the object in a molten state.

3. A temperature measurement method comprising: adjusting the simulation conditions in a simulation device that simulates changes in surface temperature and internal temperature of an object being processed to undergo a phase change; and after adjusting the simulation conditions, simulating the changes in surface temperature and internal temperature using the simulation device, wherein adjusting the simulation conditions includes detecting the surface temperature of the object with an infrared camera while processing the object to undergo the phase change; detecting the internal state of the object with an X-ray inspection machine while processing the object to undergo the phase change; and adjusting the simulation conditions using the detection results from the infrared camera and the detection results from the X-ray inspection machine.

4. The temperature measurement method according to claim 3, wherein the internal state includes the flow velocity of the material constituting the object in a molten state.

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