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一、最佳測量点的含义长絲杠在精車时,往往使用中心架以避免加工中的弯曲变形;在精密絲杠檢查中,也要設法避免由于弯曲而增加的测量誤差,尤其对于又細又长的高精度絲杠(如T4240坐标鏜床),其影响更为显著。一般說来,二級精度的絲杠(甚至有些一经的)没有足够的剛性,而且具有梯形螺紋的标准型面。但是計算和实踐都証明,在曲率半徑足够大时,絲杠軸綫的些微翹曲对工作精度并无影响,因为絲杠的拉力会产生一个力图使絲杠对准螺母中心的徑向分力。我厂試制的T4240坐标鏜床的絲杠为1級精度,长1.2米,螺距5毫米,外徑35毫米,螺紋半角15°。按規定标准,它的外徑跳动允差为60微米,或者說它的軸綫弯曲允差为30微米。精密絲杠的螺距誤差是絲杠精度的最重要一項,
First, the meaning of the best measuring point Long screw in the fine car, often use the center frame to avoid processing in the bending deformation; precision screw inspection, but also to try to avoid increased measurement error due to bending, especially for the Thin and long high-precision screw (such as T4240 coordinate boring machine), the impact is more pronounced. In general, two-level precision lead screws (even some once) are not rigid enough and have a standard profile of trapezoidal thread. However, both calculation and practice prove that when the radius of curvature is large enough, slight warping of the screw axis has no effect on the working accuracy because the pulling force of the screw produces a radial force that attempts to align the screw to the center of the nut force. I plant trial T4240 coordinate boring machine screw for a precision, length 1.2 m, pitch 5 mm, 35 mm in diameter, thread half-angle 15 °. To the required standard, it has an outer diameter runout tolerance of 60 microns, or its axis bending tolerance of 30 microns. Precision screw pitch error is the most important screw a precision,