uphand welding

例句：

1. 1. The uphand welding technique is used to join metal parts together.
   手工焊接技术用于将金属部件连接在一起。
2. 2.Uphand welding is a skill that requires years of practice and training.
   手工焊接是一项需要多年练习和培训的技能。
3. 3.In uphand welding, the welder holds the workpiece in their hands while they apply the heat.
   在手工焊接中，焊工手持工件同时施加热量。