This is a pressing safety peripheral blood collection needle, which is disposable. After use, the structure cannot be restored, so secondary blood collection cannot be carried out.
His assembly sequence is: Structure 2 is clamped into Structure 1, and the springs are pre-compressed after clamping, and some springs are stored for release. Then put the assembled structure 1 and structure 2 into structure 3, and finally assemble them into structure 4.
His working principle is: the tail end of structure 3 is small and the front end is trapezoidal. When structure 1 is pressed, it will enter the trapezoidal position of structure 3. At this time, the clamping position of structure 1 and structure 2 will become larger, and when it becomes large enough, pre-pressed structure 2 with spring will pop up. When the spring pops out of the structure 2 for .3 seconds, the finger puncture will be completed, thus achieving the purpose of blood collection.
I hope I can help you! thank you