Apparatus and Method of Measuring Workpieces

• US 20100011600A1
• Filed: 03/23/2007
• Published: 01/21/2010
• Est. Priority Date: 03/23/2006
• Status: Active Grant

• Current Assignee: Renishaw PLC
• Original Assignee: Renishaw PLC
• Inventors: McFarland, Geoffrey, Jonas, Kevyn Barry, Mamour, Khaled, Hunter, Stephen Paul
• Granted Patent: US 7,971,365 B2
• Time in Patent Office: Days
• US Class Current: 33/503
• CPC Class Codes: G01B 21/04 by measuring coordinates of points

Abstract

A method and apparatus for measuring a surface using a surface sensing device mounted on a scanning head on a member of a coordinate positioning apparatus. The coordinate positioning apparatus may be operated to produce relative movement between the scanning head and the surface profile and the scanning head includes a drive for producing rotational movement of the surface sensing probe about one or more axis. The coordinate positioning apparatus is driven to provide relative movement between the member and the surface profile in a circular path and the probe head is driven to move the surface sensing device about said one or more axes, such that the surface sensing device maintains a nominally constant lead angle. The motion of the coordinate positioning apparatus and probe head is synchronous.

Claims

1. A method for measuring a surface profile using a surface sensing device mounted on a scanning head on a member of a coordinate positioning apparatus, wherein the coordinate positioning apparatus may be operated to produce relative movement between the scanning head and the surface profile and wherein the scanning head includes a drive for producing rotational movement of the surface sensing probe about two axes, the method comprising the following steps:

driving the coordinate positioning apparatus to provide relative movement between the member and the surface profile in an arcuate, circular or spiral path;

driving the scanning head to move the surface sensing device about said one or more axes, such that the lead angle is nominally constant;

wherein the motion of the coordinate positioning apparatus and scanning head is synchronous.

3. A method according to claim 1 wherein the arcuate, circular or spiral motion of the member is about an axis which is at an angle to a central axis of the surface profile.

4. A method according to claim 1 wherein the arcuate, circular or spiral motion of the member is about an axis which is parallel but offset to a central axis of the surface profile.

5. A method according to claim 1 wherein the motion of the coordinate positioning apparatus and the scanning head is synchronised through time increments.

8. A computer readable medium on which is recorded a program for causing a computer to perform the method of claim 1.

2. A method according to claim 1 wherein the arcuate, circular or spiral motion of the member is about an axis of the surface profile.

6. A method according to claim 1 wherein the surface sensing device performs an oscillating motion.

6-1. (canceled)

7. A method according to claim 1 wherein rotational movement about at least one axis of the scanning head is used to keep the surface sensing device within its measurement range.

7-2. (canceled)

9. Apparatus for measuring a surface profile comprising a surface sensing device mounted on a scanning head on a member of a coordinate positioning apparatus, wherein the coordinate positioning apparatus may be operated to produce relative movement between the scanning head and the surface profile and wherein the scanning head includes a drive for producing rotational movement of the surface sensing probe about two axes, and a computing device, the computing device carrying out the following steps:

driving the coordinate positioning apparatus to provide relative movement between the member and the surface profile in an arcuate, circular or spiral path;

driving the scanning head to move the surface sensing device about said one or more axes, such that the lead angle is nominally constant;

wherein the motion of the coordinate positioning apparatus and scanning head is synchronous.