A Study on Instant Temperature Measurement of Laser Beam Machining and Affected Factors of IR Images
| Autor: | Wu Yu Chen, 陳伍佑 |
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| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 101 The laser beam machining process had been used widely in the metal machining process in the recent years because of its precision accuracy, and the main reason is the merit of limited area influenced by heat. However, it is hard to measure the instant temperature with phase changed at the process point. It can control the change of the material precisely to achieve the optimal machining if the temperature can be measured. It is well known that infrared (IR) thermography has been used extensively for industrial applications. However, there many possible error factors by the measurement might cause the weakness of the thermography including the distance between the IR and measured object, absolute humidity, the emissivity of the measured object, and the installation of the focus lens might affect the accuracy of the data from IR machine. There are 2 phases will be studied in this research. The Long Wave IR (8~14μm), Raytek, and Middle Wave IR (3~5μm), ThermaCAM Merlin, will be used in the phase I to measure the temperature of laser cutting. The distance between IR and measured object, absolute humidity, emissivity of the measured object, focus lens and the laser interference parameters will be discussed. Phase II will use the low power (50W) of laser machining to the metal component. Also, use the thermal couple to measure the process point and the distribution of transient temperature around the neighbor area follow by the simulation from the commercial software, COMSOL, to predict the temperature at the process point and the distribution of transient temperature. The simulation results will compare to the experiment result for verification. The experimental results showed the accuracy of Middle Wave IR is higher than Long Wave IR. But both of machines will have huge measurement error and it will increase follow by the temperature increase if the machines did not set the emissivity of the measured object properly. Also, the focusing lens is placed in a different distance position, does not affect the measurement of the temperature. The experiment of laser beam machining will use the low power (50W) to process adjacent points (1 ~ 5 mm) by using thermal couple with the numerical simulation software, COMSOL, to calculate the temperature. The maximum temperatures from the simulation and experiment measurement are 314.5°C and 262°C and the error was 17.2% by speeds 10mm/s. The percentage of error is 7.9% by deduction of the experimental systematic error and random error the error of 9.31%. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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