The geometric accuracy of large CNC machine tool processing
The geometric accuracy of large CNC machine tools comprehensively reflects the shape errors, position or displacement errors of lines and surfaces after the main parts are assembled. According to the national standard GB/T 17421.1-1998 "General rules for inspection of machine tools - Part 1: Geometric accuracy of machine tools under no-load or finish machining conditions", there are several categories as follows:
(I) Straightness
1. The straightness of a line in a plane or space, such as the straightness of the bed guide rail of a CNC horizontal lathe;
2. The straightness of components, such as the straightness of the longitudinal reference T-slot on the worktable of a CNC riser milling machine;
3. The straightness of motion, such as the straightness of the X-axis axis motion of a vertical machining center.
Length measurement methods include: straightedge and indicator method, wire and microscope method, collimating telescope method, and laser interferometer method.
Angle measurement methods include: precision level method, autocollimator method, and laser interferometer method.
(II) Flatness (such as the flatness of the worktable surface of a vertical machining center)
Measurement methods include: plate method, plate and indicator method, straightedge method, precision level method, and optical method.
(III) Parallelism, equidistance, coincidence
Parallelism of lines and surfaces, such as the parallelism of the spindle axis of a CNC horizontal lathe to the movement of the main tool post slide;
Parallelism of motion, such as the parallelism between the worktable surface and the X-axis axis of a vertical machining center;
Equidistance, such as the equidistance between the positioning hole and the rotation axis line of the worktable of a vertical machining center;
Coaxiality or coincidence, such as the coincidence of the tool hole axis with the spindle axis of a CNC horizontal lathe.
Measurement methods include: straightedge and indicator method, precision level method, indicator and inspection bar method.
(IV) Perpendicularity
Perpendicularity between a line and a plane, such as the perpendicularity between the spindle axis and the X-axis axis motion of a vertical machining center;
Perpendicularity of motion, such as the perpendicularity between the Z-axis axis and the X-axis axis motion of a vertical machining center.
Measurement methods include: straightedge and indicator method, square and indicator method, optical methods (such as autocollimators, optical squares, radiators).
(V) Rotation
Radial runout, such as the radial runout of the chuck locating taper face at the end of the spindle of a CNC horizontal lathe, or the radial runout of the spindle locating hole;
Periodic axial play, such as the periodic axial play of the spindle of a CNC horizontal lathe;
Face runout, such as the face runout of the card locating end face of the spindle of a CNC horizontal lathe.
Measurement methods include: indicator method, inspection bar and indicator method, steel ball and indicator method.
For more details, please visit: http://www.dgwanjun.com