微动开关上面有个金属片 ，压下去断开的是 常开还是常闭？反之，金属片压下去闭合的是常开还是常闭？

压下去断开的是常闭式，压下去闭合的是常开式。 一般有三只脚的的是转换式，具体用常开常闭看你需要 接线。一般三只脚的都标有NC NO COM，NC表示normal close ，也就是常闭 ，NO 表示 normal open，也就是常开，COM表示公共端子，一般需要常闭设计 线就接NC COM，常开则接NO COM。一般大一点的开关 三只脚是上中下 依次是NC NO COM，常闭设计连接一三脚即可。小一点开关 三只脚是平行的 依次也是NC NO COM 接线同理。  一般三只脚的转换型，其压片（弹簧或者铍铜簧片）联动的触点（银触点）的起始位置都停在NC脚上，也就是常闭触点上。你接一三脚 即是常闭，接二三脚即是常开 。

There is a piece of metal on the micro switch. Is it normally open or closed if you press it down? On the other hand, when the sheet metal is pressed down, is it normally open or normally closed?

Press off is normally closed, press closed is normally open. Generally has three legs is the conversion type, the specific use of normal open and close to see you need wiring. Normally, normally closed design line is connected to NC COM, normally open is connected to NO COM. Generally a little larger switch three legs is the upper middle lower order is NC NO COM, normally closed design connected to a three legs. The three legs of the smaller switch are parallel. The starting position of the contact (silver contact) of the press (spring or beryllium-copper reed) linkage of the general three-legged transition type stops at the NC foot, that is, the normally closed contact. When you have one or three legs, it is normally closed; when you have two or three legs, it is usually open.