ABSOLUTE DIAMETER MEASUREMENT ARM
First Claim
Patent Images
1. A method of determining absolute diameter of an object on a rotary table, comprising:
- given an assembly having (i) a rotary table on a base, (ii) a support tower on the base and carrying a horizontal measurement arm, and (iii) a laser device configured to indicate change in orientation of the horizontal measurement arm with respect to a centerline of rotation of the rotary table, the laser device having a laser path aligned relative to the centerline of rotation of the rotary table;
calibrating the horizontal measurement arm including determining (a) a measurement error of the horizontal measurement arm at a reference height, (b) a displacement factor bCAL of the support tower, and (c) a displacement factor α
CAL of the laser path, such that the sum of α
CAL and bCAL is a constant value;
using the horizontal measurement arm, measuring a plurality of points around a circumference of a subject object on the rotary table with the horizontal measurement arm at a height equal to or greater than the reference height, including measuring temperature of the horizontal measurement arm for each measured point and determining a thermal expansion factor;
for each measured point, determining a respective corrected point by applying the thermal expansion factor, the measurement error and a compensation factor to the measure point, the compensation factor being determined as a function of α
CAL, bCAL and height of the horizontal measurement arm relative to the reference height; and
using the determined corrected points, determining an absolute radius, and, effectively, absolute diameter, of the subject object.
1 Assignment
0 Petitions
Accused Products
Abstract
A measurement apparatus calibrated to measure an absolute diameter of a part in a shop floor environment. The measurement apparatus includes a calibration that includes compensation factors for thermal expansion, shifting of measurement parts (arm, support tower, and related laser), and variances of these parts. The resulting measurements report an absolute diameter of a part to a higher degree of accuracy than previously possible. Also, the calculated compensation factor eliminate the need for an isolated, climate-controlled measurement room.
-
Citations
23 Claims
-
1. A method of determining absolute diameter of an object on a rotary table, comprising:
-
given an assembly having (i) a rotary table on a base, (ii) a support tower on the base and carrying a horizontal measurement arm, and (iii) a laser device configured to indicate change in orientation of the horizontal measurement arm with respect to a centerline of rotation of the rotary table, the laser device having a laser path aligned relative to the centerline of rotation of the rotary table; calibrating the horizontal measurement arm including determining (a) a measurement error of the horizontal measurement arm at a reference height, (b) a displacement factor bCAL of the support tower, and (c) a displacement factor α
CAL of the laser path, such that the sum of α
CAL and bCAL is a constant value;using the horizontal measurement arm, measuring a plurality of points around a circumference of a subject object on the rotary table with the horizontal measurement arm at a height equal to or greater than the reference height, including measuring temperature of the horizontal measurement arm for each measured point and determining a thermal expansion factor; for each measured point, determining a respective corrected point by applying the thermal expansion factor, the measurement error and a compensation factor to the measure point, the compensation factor being determined as a function of α
CAL, bCAL and height of the horizontal measurement arm relative to the reference height; andusing the determined corrected points, determining an absolute radius, and, effectively, absolute diameter, of the subject object. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. A method of calibrating measurements by a horizontal measurement arm, comprising:
-
(a) given a high precision rotary table on a base, a support tower on the base carrying a horizontal measurement arm, and a laser device configured to indicate change in orientation of the horizontal measurement arm with respect to a centerline of rotation of the high precision rotary table, the laser device having a laser path aligned relative to the centerline of rotation of the rotary table; (b) determining a measurement error by; determining a first compensation factor for measurement error of a horizontal measurement arm; determining a second compensation factor for lean of a support tower carrying the horizontal measurement arm as a function of height above a reference height; determining a third compensation factor for variation of the support tower as a function of height above the reference height; determining a fourth compensation factor for thermal expansion of the horizontal measurement arm as a function of temperature; and (c) using the determined measurement error to effectively calculate measuring a plurality of points around a circumference of an object on a rotary table with the horizontal measurement arm at a height equal to or greater than the reference height, including determining a plurality of corrected points around the circumference by applying the first compensation factor, second compensation factor, third compensation factor, and fourth compensation factor to each of the plurality of points;
such that an absolute radius of the object is able to be determined by applying the plurality of corrected points in a multi-point polygon model. - View Dependent Claims (11, 12, 13, 14, 15, 16)
-
-
17. An apparatus for measuring absolute diameter of an object on a rotary table, comprising:
-
a stable base with a substantially flat surface, the base including vibration-isolating mounts to isolate the stable base from ambient vibrations; a precision rotary table mounted to the flat surface of the stable base; a support tower mounted to the flat surface of the stable base, the support tower substantially perpendicular to the flat surface; a horizontal measurement arm mounted to the support tower substantially parallel to the flat surface and configured to move towards and away from a centerline of rotation of the precision rotary table, the horizontal measurement arm configured to measure a distance of a precision gauge head on an end of the horizontal measurement arm from the centerline of rotation; a thermocouple mounted to the horizontal measurement arm configured to measure the temperature of the horizontal measurement arm; a laser mounted to a base of the support tower and pointed substantially parallel to the centerline of rotation of the rotary table, laser light from the laser aimed at a housing of the horizontal measurement arm; and a computer controller configured to; (i) determine a first compensation factor for measurement error of the horizontal measurement arm; (ii) determine a second compensation factor for lean of the support tower as a function of height above a reference height; (iii) determine a third compensation factor for variation of the support tower as a function of height above the reference height; (iv) determine a fourth compensation factor for thermal expansion of the horizontal measurement arm as a function of temperature; (v) measure a plurality of points around a circumference of an object on the rotary table with the horizontal measurement arm at a height equal to or greater than the reference height; (vi) determine a plurality of corrected points around the circumference by applying the first compensation factor, second compensation factor, third compensation factor, and fourth compensation factor to each of the plurality of points; and (vii) determining an absolute radius of the object by applying the plurality of corrected points in a multi-point polygon model. - View Dependent Claims (18, 19, 20, 21, 22, 23)
-
Specification