一、概述当工件在XY平面上,以两孔定位时,不但工件在空间的六个自由度得以消除,而且六个方向运动中的五个得到了约束。剩下的仅一个Z正向的平移运动,只要在XY平面的法向加一个F_1的夹紧力,即可得到有效的约束。这样夹具的结构可以大为简化,而且十分稳定可靠。当有足够的切削分力或工件重力垂直于XY面时,甚至连F_1也可不要施加。两孔定位具有简化夹具结构、定位稳定可靠、操作简便等优点,从而在生产实践中 I. Overview When the workpiece in the XY plane, with two holes positioning, not only the workpiece in the six degrees of freedom to be eliminated, and the six directions of the movement of the five constraints. The remaining only one Z positive translational movement, as long as the normal in the XY plane plus a F_1 clamping force, you can get an effective constraint. This fixture structure can be greatly simplified, and very stable and reliable. When sufficient cutting force or workpiece gravity perpendicular to the XY plane, even F_1 do not apply. Two-hole positioning with a simplified fixture structure, positioning stable and reliable, easy to operate, etc., in production practice