projection welder

例句：

1. 1.The projector is a tool used to project images onto a screen.
   投影仪是一种用来将图像投射到屏幕上的工具。
2. 2.The engineer used the projection welder to fix the leaky pipe.
   工程师使用投影焊接机来修理漏水的管道。
3. 3.The projector and the projection welder were both used for educational purposes.
   投影仪和投影焊接机都被用于教育目的。