Method of calibrating probe pins on multicoordinate measurement machines

• US 4,523,450 A
• Filed: 09/20/1982
• Issued: 06/18/1985
• Est. Priority Date: 11/07/1981
• Status: Expired due to Fees

• Current Assignee: D/B/U Carl Zeiss Carl Zeiss-Stiftung
• Original Assignee: Carl-Zeiss-Stiftung
• Inventors: Herzog, Klaus
• Primary Examiner(s): Frankfort, Charles E.
• Assistant Examiner(s): Corr, Denis E.
• Application Number:
  US06/420,104
• Time in Patent Office: 1,002 Days
• Field of Search: 73/1 J, 33/174 H, 33/174 R, 33/174 PC, 33/185 R, 33/168 R
• US Class Current: 73/1.81
• CPC Class Codes: G01B 21/042 Calibration or calibration artifacts G01B3/30, G01B9/02072 take precedence
• CPC Class Codes: G01B 3/30 Bars, blocks, or strips in which the distance between a pair of faces is fixed, although it may be preadjustable, e.g. end measure, feeler strip

Abstract

This invention contemplates a rapid method of calibrating probe-pin combinations, such as star probes or rotary-swing probes, which method is applicable when the probe system forms part of or is coupled to the control system of a measuring machine wherein a self-centering probe of workpieces is possible. The calibration procedure employs a calibration standard having a plurality of probe-centering elements distributed over its surface and facing in different directions, the positional geometry of these elements being stored in the computer of the measuring machine. Each of the individual probe balls is successively introduced into a centering element which is accessible. Thereupon, the position of each ball-center point is determined in the computer, from the stored positional data and the pre-established diameter of corresponding probe balls.

Claims

1. A method of calibrating a probe having several probe pins with a probe ball at the end of each pin, wherein the probe is mounted to a self-centering probe-measurement system of a multicoordinate measurement machine, characterized by the fact that:

(a) a calibration standard which has several centering elements formed of surfaces which converge towards each other is fastened to the measurement machine, said centering elements being distributed over the standard and facing in different directions,

(b) the geometry of the centering elements (shape and distances apart) as determined by measurement is stored in the computer of the coordinate measurement machine, each centering element being imparted an identifier,

(c) the orientation of the calibration standard is determined relative to the coordinate system of the measurement machine,

(d) each of the balls of the various probe pins is introduced once in self-centering manner into a selected one of the centering elements,

(e) the diameters or identifiers of the probe balls or ball used and the identifiers of the associated centering elements are fed into the computer, and that thereupon,

(f) a program is called up which, on basis of the data and measurement values fed, computes the relative position of the center points of the probe balls with respect to each other.

2. A method according to claim 11, characterized by its use for the calibrating of probe-ball combinations having probe balls of different size.

3. A method according to claim 1, characterized by its use for the calibration of a swing probe.

11. A method according to claim 1, characterized by its use for the calibration of a probe having plural probe pins extending in different directions with a probe ball at the tip of each pin.

4. In a calibration standard for the calibration of probe pins having probe balls at the ends thereof and which are fastened to self-centering probe-measurement systems of multicoordinate measurement machines, the improvement wherein the calibration standard has several centering elements facing in different directions and formed of convergent surfaces which permit the self-centering reception of probe balls of different diameters.

5. A calibration standard according to claim 4, characterized by the fact that the calibration standard has the shape of a cube, with at least one convergent-surface centering element on each of several of the surfaces of the cube.

6. A calibration standard according to claim 4, characterized by the fact that the calibration standard has the shape of a ball, with several convergent-surface centering elements in angularly spaced distribution over the surface of the ball.

7. A calibration standard according to claim 4, characterized by the fact that each of the centering elements is developed as an outwardly flaring conical cavity.

8. A calibration standard according to claim 4, characterized by the fact that each of the centering elements is developed in concave generally tetrahedron shape.

9. In a calibration standard for the calibration of probe pins having probe balls at the ends thereof and which are fastened to self-centering probe-measurement systems of multicoordinate measurement machines, the improvement wherein the calibration standard has a plurality of centering elements formed of convergent surfaces which permit the self-centering reception of probe balls of different diameters, each of the centering elements comprising three balls disposed in touching relationship upon the surface of a polyhedron.

10. In a calibration standard for the calibration of probe pins having probe balls at the ends thereof and which are fastened to self-centering probe-measurement systems of multicoordinate measurement machines, the improvement wherein the calibration standard has a plurality of centering elements formed of convergent surfaces which permit the self-centering reception of probe balls of different diameters, each of the centering elements comprising three cylinders extending at an angle from the face of a polyhedron, said cylinders converging toward said surface.