calking iron

例句：

1. 1. The calking iron was used to connect the two pieces of metal together.
   焊接铁被用来将两块金属连接在一起。
2. 2.The welding rod was heated up and then inserted into the joint.
   焊条被加热后插入到接缝处。
3. 3.The welding process requires precise control over the temperature and pressure.
   焊接过程需要精确控制温度和压力。