本文選題：電阻點焊 + 過程監(jiān)控�。� 參考：《哈爾濱工業(yè)大學》2017年碩士論文

【摘要】：電阻點焊作為一種生產(chǎn)效率高、實現(xiàn)簡單、成本低的連接方法,廣泛應用于汽車生產(chǎn)中。但由于焊接工藝選擇不合適、焊接參數(shù)波動、工人操作不當?shù)仍?往往導致現(xiàn)場焊接質(zhì)量不穩(wěn)定。由于焊點質(zhì)量檢測往往需要抽樣破壞性檢驗,此舉既浪費成本又不具代表性,因此實現(xiàn)電阻點焊過程在線監(jiān)測是工業(yè)現(xiàn)場的迫切需求。本文首先介紹了課題組針對實際現(xiàn)場需求,以STM32F303ZET6單片機及EasyARM-i.MX283開發(fā)板套件分別作為系統(tǒng)工作核心和計算交互核心,制作的一套能夠穩(wěn)定應用于電阻點焊生產(chǎn)現(xiàn)場的監(jiān)控設備。該監(jiān)控設備具有焊接過程多路模擬量信號采集功能,并能將采集信號進行文件存儲并在系統(tǒng)的TFT屏上實時顯示;具有焊接生產(chǎn)輔助功能,用戶可以將當前工藝信息,如車輛數(shù)、焊點編號和組數(shù)等進行輸入,每次焊接可以對工藝信息進行更新;可監(jiān)測生產(chǎn)漏焊、多焊等情況,并可通過語音進行提示;另外,系統(tǒng)還具有以太網(wǎng)通信功能,可以通過上位PC機監(jiān)測系統(tǒng)工作狀態(tài),為車間的網(wǎng)絡化生產(chǎn)管理提供條件。之后介紹了點焊監(jiān)控器在一汽紅旗焊接現(xiàn)場的功能驗證。經(jīng)驗證,系統(tǒng)在現(xiàn)場的交直流電阻點焊機均能穩(wěn)定地完成信號采集、焊點信息與焊接參數(shù)曲線交互、焊點文件生成、以太網(wǎng)通信等功能。在焊點文件存儲上,對直流電阻焊機,可以對每個逆變半波的焊接電流、電壓、電阻、通流比等信息進行存儲,也可以在80k Bit/s速度下完成焊接瞬時值的存儲;對交流電阻焊機,可以對焊接電流、電網(wǎng)電壓和原邊電壓以80k Bit/s速度下存儲,并在文件末尾存儲焊接過程的觸發(fā)角和導通角數(shù)值。本文最后介紹了對中頻直流電阻焊簡化計算模型的推導和對現(xiàn)場采集數(shù)據(jù)的初步分析。在模型推導上,得出理想恒占空比、恒壓、電阻電感恒定條件下的焊接電流計算公式。根據(jù)實驗和經(jīng)驗數(shù)據(jù),估算電流達到穩(wěn)態(tài)時間約為10ms。推導了電感剔除式的動態(tài)電阻算法,通過數(shù)據(jù)仿真和實際數(shù)據(jù)驗證,其電阻計算精度在電流未穩(wěn)定時優(yōu)于傳統(tǒng)平均值算法,且該方法計算回路電感值在焊接過程基本保持穩(wěn)定。通過計算不同焊接條件電感值,發(fā)現(xiàn)電感值對于焊接條件不敏感,不同電感相對中心值波動范圍為-0.61%~1.52%。鐵磁物伸入條件下平均電感值顯著增加,較正常焊接條件平均電感值中心提升2.26%~3.76%。在數(shù)據(jù)初步分析上,比較了不同材料的動態(tài)電阻曲線特征,并選取電阻具有明顯峰谷值特征的DP240材料進行多次試驗,分析了焊接電流、工件層數(shù)和板厚對焊接過程的影響。介紹了基于動態(tài)電阻的飛濺識別和飛濺特征值計算方法,并通過提取動態(tài)電阻初始電阻、初始谷值時刻、初始谷值電阻等飛濺發(fā)生前的特征值,利用GRNN、PNN、SVM算法,對飛濺的產(chǎn)生進行預測。改變訓練集和測試集分別運行500次,得到各算法判斷正確率達87.5%以上的次數(shù)占總運行次數(shù)的比例分別為92.2%、95.0%和89.2%,很好的完成了焊接飛濺的預測工作。
[Abstract]:Resistance spot welding is widely used in automobile production as a connection method with high production efficiency, simple realization and low cost. However, due to improper selection of welding process, fluctuation of welding parameters and improper operation of workers, the quality of welding is often unstable. It is not only a waste of cost and non representativeness, so it is an urgent need to realize the on-line monitoring of resistance spot welding process. This paper first introduces a set of STM32F303ZET6 singlechip and EasyARM-i.MX283 development board suite as the core of the system and the core of the calculation interaction. The monitoring equipment is used in the field of resistance spot welding production. The monitoring equipment has multi analog signal acquisition function in welding process, and can store the collected signal and display it on the TFT screen in real time. With the auxiliary function of welding production, the user can make the current information of the work, such as the number of vehicles, the number of solder joint and the number of groups. In line input, the process information can be updated each time, the production leakage welding and multi welding can be monitored. The system can be prompted by voice. In addition, the system also has Ethernet communication function. The system can monitor the working state of the system through the upper PC machine and provide conditions for the network production management of the workshop. Then the spot welding monitor is introduced. It is verified that the AC and DC resistance spot welder in the field can accomplish the signal acquisition, the interaction of welding point information and the welding parameter curve, the welding point file generation, the Ethernet communication and so on. On the storage of solder joint, the welding current of each inverter half wave can be applied to the DC electric resistance welding machine. The voltage, resistance, flow ratio and other information are stored, and the welding instantaneous value can be stored at the speed of 80K Bit/s. For the AC resistance welding machine, the welding current, the grid voltage and the original side voltage can be stored at the speed of 80K Bit/s, and the trigger angle and the conduction angle value of the welding process are stored at the end of the file. The derivation of simplified calculation model of frequency DC resistance welding and the preliminary analysis of data collected on the spot. In the model derivation, the formula of welding current calculation under constant constant duty ratio, constant pressure and constant resistance inductance is obtained. According to the experimental and empirical data, the estimation of the dynamic resistance of inductor elimination is derived from the estimated current when the current reaches the steady state of 10ms.. The algorithm, through data simulation and actual data verification, its resistance calculation precision is better than the traditional average value algorithm when the current is not stable, and the method calculates the inductance value of the loop in the welding process basically stable. By calculating the inductance value of different welding conditions, it is found that the inductance value is insensitive to the welding condition and the different inductance is relative to the central value wave. The average inductance value of the -0.61%~1.52%. ferromagnetic field is significantly increased and the average inductance value center of the normal welding condition is raised by 2.26%~3.76%.. The dynamic resistance curve of different materials is compared with the average inductance value center of the normal welding condition, and the DP240 material with the characteristic of obvious peak and valley value is selected for multiple tests and the welding welding is analyzed. The influence of the current, the number of workpiece layers and the thickness of the plate on the welding process. The method of spatter identification based on dynamic resistance and the calculation method of spatter characteristic value are introduced, and the characteristics of the splash before the initial resistance of dynamic resistance, the initial valley value time, the initial valley value resistance and so on are extracted. The GRNN, PNN and SVM algorithms are used to predict the generation of spatter. The training set and the test set run 500 times respectively. The ratio of the number of times to the total operation times is 92.2%, 95% and 89.2% respectively, and the prediction of the welding spatter is completed.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG438

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