【摘要】：熔池的表面能會反映出焊縫的成形、焊縫的外觀和內(nèi)在質(zhì)量。因此,本文主要從TIG焊熔池表面方面展開的一系列研究工作。提出了一種熔池三維表面恢復(fù)方法。通過將結(jié)構(gòu)激光投射到熔池表面,來采集結(jié)構(gòu)激光隨熔池表面形貌變化的反射圖像。同時,建立熔池表面高度與反射激光之間的關(guān)系,通過得到的反射激光圖像和對應(yīng)的幾何參數(shù)恢復(fù)出溶池表面三維形貌。利用這種方法能夠?qū)崟r的獲得熔池三維表面形貌,監(jiān)測熔池中液態(tài)金屬流動,從而在不增加焊接生產(chǎn)成本的基礎(chǔ)上提高了焊接過程的可控性,反映了更豐富的熔池表面三維信息,對獲得成形美觀的焊縫和提高焊接智能化具有理論和實際指導(dǎo)意義。首先,介紹了TIG焊熔池三維表面行為演化研究的觀測試驗平臺,利用熔池表面類鏡面反射反射特性,提出了利用結(jié)構(gòu)激光投射熔池表面觀測其三維形貌的方法和基于網(wǎng)格結(jié)構(gòu)激光的TIG焊熔池三維表面的恢復(fù)算法;利用此觀測方法觀測了定點TIG焊熔池三維表面的演化行為,通過熔池表面的恢復(fù)算法獲得了熔池表面的三維形貌。使用FLOW-3D軟件建立了定點TIG焊熔池三維表面的數(shù)學(xué)模型,并進行數(shù)值分析。通過對比焊后的熔池形貌,發(fā)現(xiàn)試驗結(jié)果和數(shù)值模擬結(jié)果基本吻合。其次,從試驗角度對焊接參數(shù)階躍(電流階躍和速度階躍)、脈沖TIG焊、TIG填絲焊熔滴對熔池三維表面的影響進行了探究,利用仿真和試驗相結(jié)合的方法對TIG焊的熔池表面動態(tài)演化過程進行分析。結(jié)果表明:從低電流階躍到高電流時,熔池表面變形變化不大;從高電流階躍到低電流時,熔池表面變形發(fā)生明顯的變化;階躍電流之間的差值越大,熔池表面的變形越劇烈。從低速度階躍到較高速度時,網(wǎng)格激光在熔池上的數(shù)量減少,熔池表面積先減小再增大,最后趨于穩(wěn)定;從高速度階躍到較低速度時,網(wǎng)格激光在熔池上的數(shù)量增加,熔池表面積增大。通過對TIG填絲焊熔池表面的分析,可以發(fā)現(xiàn):焊后熔池的形貌及試驗結(jié)果與恢復(fù)結(jié)果之間存在一定的誤差,整體形貌相符。從數(shù)值模擬分析中得出:熔滴下落過程會引起熔池自由表面發(fā)生下凹;熔滴進入熔池,改變了熔池原有溫度場和流場的分布,引起熔池自由表面發(fā)生嚴重的變形,使熔池自由表面隨時間做阻尼振動。最后,分析了不同焊接速度對TIG焊熔池三維表面演化的影響,根據(jù)采集系統(tǒng)采集到的反射激光圖像對不同焊接速度下的TIG焊熔池三維表面進行恢復(fù)重構(gòu)并且與試驗結(jié)果進行對比。為了研究快速TIG焊焊駝峰焊道的形成機理,基于FLOW-3D建立了TIG焊駝峰焊道的數(shù)學(xué)模型,分析了快速移動的TIG焊駝峰焊道溫度場、流場和自由表面的變化情況,同時也分析了快速移動的TIG焊熔池表面凸起和下凹形成的原因。通過分析液態(tài)金屬凝固后示蹤粒子在熔池中分布情況,發(fā)現(xiàn)表層預(yù)先分布的粒子,熔池凝固后部分位于駝峰中,部分位于焊縫中心或者熔合線附近,由此可以得出:在TIG焊熱力耦合作用下,液態(tài)金屬的流動不是表面流動。
[Abstract]:The surface of the molten pool can reflect the formation of the weld, the appearance and the internal quality of the weld. Therefore, a series of research work on the surface of the TIG weld pool is mainly carried out in this paper. A method for the recovery of the three-dimensional surface of the molten pool is proposed. At the same time, the relationship between the surface height of the molten pool and the reflected laser is established, and the three-dimensional morphology of the dissolved pool surface is restored by the obtained reflected laser image and the corresponding geometric parameters. By this method, the three-dimensional surface morphology of the molten pool can be obtained in real time, and the liquid metal flow in the molten pool can be monitored without increasing the cost of the welding production. On the basis of this, it improves the controllability of the welding process, reflects the more abundant three-dimensional information on the surface of the molten pool, and has the theoretical and practical guiding significance for obtaining the beautiful weld seam and improving the welding intelligence. First, the observation test platform for the study of the three-dimensional surface behavior evolution of the TIG weld pool is introduced, and the mirror reflection reflection on the surface of the molten pool is used. The method of using the surface of the molten pool surface to observe its three-dimensional morphology and the restoration algorithm of the three-dimensional surface of the TIG weld pool based on the grid structure laser are proposed. The three-dimensional surface evolution behavior of the fixed point TIG welding pool is observed by this method, and the three-dimensional morphology of the surface of the molten pool is obtained by the recovery algorithm on the surface of the molten pool. The mathematical model of the three-dimensional surface of the fixed point TIG welding pool was established by using the FLOW-3D software, and the numerical analysis was carried out. By comparing the weld pool morphology after the welding, it was found that the experimental results were basically identical with the numerical simulation results. Secondly, the step of welding parameters (current step and speed step), pulse TIG welding, and TIG filler metal welding droplets were three The influence of the surface is explored and the dynamic evolution process of the molten pool surface of TIG welding is analyzed by the combination of simulation and test. The results show that the surface deformation of the molten pool is not very changed from the low current step to the high current; the surface deformation of the molten pool changes obviously from the high current step to the low current, and the step current is between the step current. The larger the difference, the deformation of the surface of the molten pool is more dramatic. From the low speed step to the higher speed, the number of grid laser on the pool is reduced, the surface area of the molten pool decreases first and then increases, and finally tends to be stable. The number of grid laser on the pool increases and the surface area of the molten pool increases from the high speed step to the lower speed. The surface area of the molten pool is increased. By welding the TIG filler wire, the weld pool surface area is increased. The analysis of the surface of the molten pool shows that there is a certain error between the morphology of the post weld pool and the result of the test and the result of the recovery. It is concluded from the numerical simulation that the drop process of the droplet will cause the free surface of the molten pool to be concave; the droplet enters the molten pool and changes the original temperature field and the distribution of the flow field in the molten pool and causes the melting of the molten pool. The free surface of the pool has serious deformation, which makes the free surface of the pool vibration damping with time. Finally, the influence of different welding speed on the three-dimensional surface evolution of the TIG weld pool is analyzed. According to the reflected laser image collected by the acquisition system, the 3D surface of the weld pool of the weld pool at different welding speeds is reconstructed and the results are compared with the experimental results. In order to study the formation mechanism of the rapid TIG welding hump welding track, a mathematical model of the TIG welding hump welding path is established based on FLOW-3D. The temperature field of the fast moving TIG welding hump welding path, the change of the flow field and the free surface are analyzed, and the reasons for the formation of the protruding and lower concave surface of the fast moving TIG weld pool are also analyzed. After the analysis of the distribution of the tracer particles in the molten pool after the solidification of liquid metals, it is found that the pre distributed particles in the surface are located in the hump, partly located in the center of the weld or near the fusion line. Thus, it is concluded that the flow of the liquid gold is not a surface flow under the thermal coupling of TIG welding.
【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG444.74

【參考文獻】

相關(guān)期刊論文 前10條

1 何笑英;黃健康;石s，

本文編號：2141848