摘要：TOP-TIG焊是一种新型的焊接方法，其特点是送丝嘴与焊枪集成设计。TOP-TIG焊的焊丝通过喷嘴精确送入电弧中热量最高的区域，可达到MIG焊一样的焊接速度，生产效率高，同时兼备传统TIG焊高的焊接质量的优点。适用机器人焊接，可满足绝大部分工业应用，包括对焊缝质量要求高的，如汽车、化工、食品机械等行业。

本文通过改变焊接电流、送丝速度进行TOP-TIG焊实验，借助于数字化焊接相机拍摄TOP-TIG焊熔滴过渡过程并对熔滴过渡过程进行分析。研究了电流为240A-280A，送丝速度为25-40cm/min时TOP-TIG焊熔滴过渡过程。

研究发现，送丝速度是影响TOP-TIG焊熔滴过渡的主要因素，焊接电流对TOP-TIG焊熔滴过渡的影响不大。在电流240A-280A，送丝速度25-40cm/min时，随着送丝速度的增加，TOP-TIG焊熔滴的过渡方式改变，熔滴的尺寸减小，送丝速度每增加5cm/min，熔滴的等效直径分别减小10%、12%、15%；熔滴的过渡频率增加，送丝速度每增加5cm/min，过渡频率分别增加15%、45%、492%。熔滴过渡频率在35-40cm/min时增加了492%，此时过渡方式发生了变化。随着焊接电流的增加，熔滴的尺寸和过渡频率变化不大。

根据送丝速度不同，TOP-TIG焊熔滴过渡形式有滴状过渡和连续接触过渡两种形式。电流为240A时，TOP-TIG焊熔滴过渡方式由滴状过渡转变为连续接触过渡的临界送丝速度值为35cm/min；电流为260A时，熔滴过渡转变的临界送丝速度值为40cm/min。焊接电流增加，会使TOP-TIG焊熔滴过渡形式由滴状过渡转变为连续接触过渡的临界送丝速度值增加。

TOP-TIG焊熔滴过渡形式为连续接触过渡时，过渡过程稳定，熔敷效率高，焊接速度快，可以达到MIG焊的焊接速度。

关键词：TOP-TIG焊接；熔滴过渡；焊接电流；送丝速度

Abstract：TOP-TIG welding is a new type of welding method, which is characterized by integrated design of wire feeding nozzle and torch. TOP-TIG welding wire through the nozzle accurately into the arc of the highest heat area, can achieve the same MIG welding speed, and has high production efficiency. It is applicable to robot welding, and meet the vast majority of industrial applications, including high quality requirements of the weld, such as automotive, chemical, food machinery and other industries.

In this paper, TOP-TIG welding experiment was carried out by changing the welding current and wire feeding speed. The process of droplet dropping of TOP-TIG welding was carried out by means of digital welding camera and the process of droplet transfer was analyzed. The droplet transfer process of TOP-TIG welding was studied when the current was 240A-280A and the wire feeding speed was 25-40cm / min.

It is found that the wire feed speed is the main factor affecting the droplet transfer of TOP-TIG welding. The welding current has little effect on the droplet transfer of TOP-TIG welding. When the current is 240A-280A and the wire feeding speed is 25-40cm / min, the change of the droplet of TOP-TIG welding is changed with the increase of the wire feeding speed. The size of the droplet is reduced and the wire feeding speed is increased by 5cm / min , The equivalent diameter of the droplet is reduced by 10%, 12% and 15% respectively. The transition frequency of the droplet increases, and the transmission frequency increases by 15%, 45% and 492% respectively for every 5cm / min increase. The droplet transfer frequency increased by 492% at 35-40 cm / min, and the transition mode changed. With the increase of welding current, the droplet size and transition frequency do not change much.

According to the different wire feed speed, TOP-TIG welding droplet transition form of droplet transition and continuous contact transition in two forms. When the current is 240A, the critical wire feed speed  of  TOP-TIG  welding  droplet  transition  is  35cm  / min .When the droplet transition is changed to the continuous contact transition. When the current is 260A, the critical wire feed speed of the droplet transition is 40cm / Min. The increase in welding current increases the critical wire feed speed of the TOP-TIG weld droplet transition from droplet transition to continuous contact transition.