C.
Description of the sequential step diagonal path The machine spindle is programmed to move in a diagonal path
within the working volume, starting from one
corner at the base plan and moving
to the opposite corner at the top
plan. There are eight body diagonals. We define the eight body diagonals by the
positive or negative axis
movement. For example, ppp means from the starting
corner (smallest machine coordinates) to the
opposite corner (largest machine
coordinates); all three axes move with positive increments. The npn means from
the starting corner (largest x-axis
coordinate, smallest machine y-axis
coordinate, and largest z-axis coordinate) to the opposite corner
(smallest x-axis coordinate,
largest machine y-axis coordinate, and smallest z-axis coordinate), the
y-axis moves with positive increments and
the x axis and z axis move with negative increments. The eight body diagonals
are ppp, npp, pnp, ppn, nnn,
pnn, npn, and nnp. The last four body diagonals are the
same corners as the first
four diagonals except the directions are reversed. Hence, there are only four body diagonal directions with
forward movement and reverse movement
(bidirectional). More specifically, first
define the starting point (Xs, Ys, and Zs) and the end point (Xe, Ye, Ze) for the
first diagonal ppp. The working volume is
defined by (Xe-Xs)*(Ye - Ys ) * ( Ze - Zs ) . The number
of increments per axis is n
and the total number of increments is 3n. The
measurement increments X, Y, and Z, which
are limited by the size of the flat mirror,
and the number of steps per axis n, are determined by
the following relations:
X=(Xe-Xs)ln,
Y=(Ye-Ys)ln,
and Z=(Ze-Zs)ln. The machine spindle is programmed to move in an XYZ sequence as
shown in Fig. 2, that is, starting from
(Xs, Ys, and Zs). More X in the x
direction at a feed rate F (usually
between 20% and 80% of the
maximum feed rate). Stop for a dwell time
of T seconds (usually 1-5 s,
depending on the machine
structure), then move Y
in the y direction at the same feed rate and stop for the same dwell
time, then move Z in the
z direction at the same feed rate
and dwell time. Continue
the sequence until the opposite corner
is reached. For bidirectional data, reverse sequence to
ZYX back on the diagonal path. For this diagonal, since all three increments are
positive, we call this ppp, and the reverse
nnn. For the second
diagonal, npp or the reverse pnn,
change the starting point to Xe, Ys, and Zs and the increments to -X, Y, and Z.
Similarly, for the third
diagonal npn the starting point is Xe,
Ys, Ze with increments of -X, Y, and
-Z. For the fourth diagonal ppn the starting point is Xs, Ys, Ze with increments of X, Y, and - Z.
For most of the tests here
the working volume is 500 mm X 500 mm X 500 mm. The increments are X = 25 mm, Y= 25 mm, and Z=
25 mm, and the number of steps is n = 20. D. Data collection and processing Using the Optodyne WindowsTM software, 3
the data collections are automatic.
Once the data from each diagonal are collected, click on the four diagonal in the analysis portion of the program and
enter all four files, and the volumetric
errors for the x-axis motion, y-axis motion, and z-axis motion can be calculated and plotted. The
results can be saved as output files to
generate compensation files. E. Machine
compensation procedure First
measure the volumetric positioning errors of
the machine without
compensation. Use the analysis software to
calculate the volumetric
positioning errors and save the data in an output file. Use an appropriate program to convert the Click here to
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