DOUBLE CONE STYLUS, TOUCH PROBE, AND METHOD OF CALIBRATING DOUBLE CONE STYLUS

• US 20140109420A1
• Filed: 10/17/2013
• Published: 04/24/2014
• Est. Priority Date: 10/19/2012
• Status: Active Grant

• Current Assignee: Mitutoyo Corporation
• Original Assignee: Mitutoyo Corporation
• Inventors: KURIHARA, Masaki, TAKAHAMA, Yasuhiro, ARAI, Masanori, MIYAZAKI, Tomoyuki
• Granted Patent: US 9,341,460 B2
• Time in Patent Office: Days
• US Class Current: 33/502
• CPC Class Codes: G01B 21/042 Calibration or calibration artifacts G01B3/30, G01B9/02072 take precedence
• CPC Class Codes: G01B 5/012 Contact-making feeler heads therefor
• CPC Class Codes: G01B 5/016 Constructional details of contacts
• CPC Class Codes: G01B 7/012 Contact-making feeler heads therefor

Abstract

A double cone stylus includes a shank and a double cone-shaped tip attached to the tip end of the shank, the double cone-shaped tip being a rotationally symmetric body obtained by rotating a triangle having a base extending along the shank around the shank as the symmetric rotation axis. The double cone stylus allows the shape of an inner wall surface of a measurement object with the inner wall surface retracted from an upper reference plane to be measured from above.

Claims

1. A double cone stylus for use in a coordinate measuring machine or a contour measuring machine, comprising:

a shank having a tip end; and

a double cone-shaped tip attached to the tip end of the shank, the double cone-shaped tip being a rotationally symmetric body obtained by rotating a triangle having a base extending along the shank around the shank as a symmetric rotation axis.

2. The double cone stylus according to claim 1, wherein at least one of a tip end and a circumferential edge of the double cone-shaped tip are rounded.

3. A touch probe for coordinate measurement or shape measurement, comprising the double cone stylus according to claim 1.

4. A coordinate measuring machine or contour measuring machine comprising the touch probe according to claim 3.

5. The coordinate measuring machine or contour measuring machine according to claim 4, further comprising a vision probe.

6. A method of calibrating a double cone stylus included in a coordinate measuring machine or contour measuring machine including a touch probe having the double cone stylus attached to a tip end thereof, the method comprising, when dimensions of a stylus tip of the double cone stylus are calibrated:

disposing a master ball with a calibration value in the coordinate measuring machine or contour measuring machine;

performing touch measurement on the master ball using the touch probe to acquire a center position and a radius of the master ball;

computing a radius of the stylus tip in a horizontal direction;

performing touch measurement to determine a position of an apex of the master ball using the touch probe to acquire a height of the apex of the master ball; and

computing a radius of the stylus tip in a height direction.

7. The method of calibrating a double cone stylus according to claim 6, wherein

the radius of the stylus tip in the horizontal direction is computed by:

determining provisional values of the center position of the master ball using values measured near the apex of the master ball;

performing measurement on the master ball along search lines extending in a vertical direction around an equator of the master ball that is determined from the measured provisional values of the center position to thereby determine final values of the center position of the master ball and a final value of the radius of the master ball; and

computing the radius of the stylus tip in the horizontal direction using the measured final value of the radius of the master ball, and

wherein the radius of the stylus tip in the height direction is computed by performing touch measurement at the center position of the master ball to determine the position of the apex of the master ball.

8. A method of calibrating a double cone stylus included in a coordinate measuring machine or contour measuring machine including a vision probe and a touch probe having the double cone stylus attached to a tip end thereof, the method comprising, when dimensions of a stylus tip of the double cone stylus and an offset between the touch probe and the vision probe are calibrated:

disposing a master ball with a calibration value and a ring gauge on the coordinate measuring machine or contour measuring machine; and

performing measurement sequentially on the mater ball and the ring gauge using the touch probe and the vision probe to calibrate the dimensions of the stylus tip and the offset between the touch probe and the vision probe.

9. The method of calibrating a double cone stylus according to claim 8, wherein an offset distance between the touch probe and the vision probe is computed by performing measurement on the ring gauge using the vision probe and the touch probe sequentially.

10. The method of calibrating a double cone stylus according to claim 9, wherein an offset distance between the vision probe and the touch probe in a horizontal direction is computed by:

measuring a circle center position of the ring gauge using the vision probe; and

measuring the circle center position of the ring gauge using the touch probe.

11. The method of calibrating a double cone stylus according to claim 9, wherein an offset distance between the vision probe and the touch probe in a height direction is computed by:

measuring a position of an upper surface of the ring gauge using the vision prove; and

measuring a height when the touch probe touches the upper surface of the ring gauge.