定點銲接熱傳與應力分析在空調壓縮機組裝之應用;Application of Thermal and Mechanical Analysis of Fixed-Point Welding on Air-Conditioning Compressor Assembly

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Title:	定點銲接熱傳與應力分析在空調壓縮機組裝之應用;Application of Thermal and Mechanical Analysis of Fixed-Point Welding on Air-Conditioning Compressor Assembly
Authors:	宋程智;Sung, Cheng-Chih
Contributors:	機械工程學系
Keywords:	銲接;溫度分佈;殘留應力;Welding;Temperature distribution;Residual stress
Date:	2017-08-22
Issue Date:	2017-10-27 16:20:56 (UTC+8)
Publisher:	國立中央大學
Abstract:	本研究利用有限元素法建立一套應用於家用空調迴轉式壓縮機缸體與外殼組裝銲接之電腦輔助工程分析技術。首先，利用兩平板單點銲接建立一套模擬固定銲接之有限元素分析模型，並透過實驗驗證模擬分析之結果，確認該有限元素分析模型之有效性之後，再進一步應用於模擬迴轉式壓縮機三點銲接，預測相關零件之溫度分佈、變形及殘留應力。本研究探討兩種熱源輸入方式，平均熱源模型及高斯分佈熱源模型，發現平均熱源模型可獲得較佳之兩平板單點銲接溫度分析結果。有限元素分析模型計算求得之兩平板單點銲接的溫度分佈，與實驗量測結果比對，不管在溫度變化趨勢及溫度數值方面都相當吻合，因而確認有限元素分析模型的有效性。此外，在特定點所量測之應變變化趨勢及數值也都與模擬的預測值有一致性的吻合，再次確認本研究所發展之有限元素分析模型計算銲接過程應變及應力變化的有效性。計算結果發現單點固定銲接結束後，銲接核心區域承受徑向張應力及切線向張應力，熱影響區外的區域則殘留徑向壓應力及切線向張應力，由於部分高殘留應力區域之von-Mises等效應力接近材料之降伏強度值，預期塑性變形將會發生於這些區域。為了確認銲接順序對迴轉式壓縮機缸體與外殼組裝銲接所產生之溫度及變形的影響，本研究進行了三點同步銲接及三點不同順序銲接之模擬分析，計算其溫度、變形及殘留應力分佈，並比較其差異性。目前已完成溫度分佈的模擬計算，模擬分析結果顯示，當第一個銲接孔為較靠近缸體葉片槽之點，可得到較平均之溫度分佈結果。 ;The objective of this study is using finite element method (FEM) to develop a computer-aided-engineering (CAE) technique for application in the welding of pump cylinder and outer shell of a rotary compressor used in household air conditioning. In this study, an FEM model for single-point welding of two plates are firstly developed to simulate the fixed-point welding process. After validation by counterpart experiments, the FEM modeling is applied to simulate the three-point welding process in a rotary compressor and to predict the temperature distribution, deformation, and residual stress in relevant components. Temperature distributions in the single-point welding of two plates are calculated by the FEM simulation and compared with the experimental measurements. A uniform heat flux model is proved to be better than the Gaussian-distribution heat flux model in predicting the temperature distribution for single-point welding of two plates. Simulation results of both temperature and strain variations at selected positions on the upper surface of the top plate show a good agreement with the experimental measurements. Variations of normal stress at the selected positions show a quarter symmetry, which also verifies the effectiveness of the FEM model developed for fixed-point welding. The filler region is subjected to tensile radial and hoop stresses after welding, while compressive radial stress and tensile hoop stress are present in the regions outside the HAZ. Plastic deformation might take place in the core of the HAZ as the calculated von-Mises equivalent stress is close to the yield strength of the material. In the three-point welding of cylinder and outer shell, temperature variation around the vane groove region is influenced by the sequence of feeding the three filler holes. A more uniform temperature distribution is observed when the first feeding hole is close to the vane groove.
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