Method for determining the shape of a workpiece

• US 20110010124A1
• Filed: 07/08/2010
• Published: 01/13/2011
• Est. Priority Date: 07/08/2009
• Status: Active Grant

• Current Assignee: Hommel-Etamic GmbH (Jenoptik AG)
• Original Assignee: Hommel-Etamic GmbH (Jenoptik AG)
• Inventors: Wegmann, Heinz
• Granted Patent: US 8,725,446 B2
• Time in Patent Office: Days
• US Class Current: 702/105
• CPC Class Codes: G01B 5/003 Measuring of motor parts
• CPC Class Codes: G01B 5/201 for measuring roundness

Abstract

Method for measuring the shape of a workpiece includes a measuring sensor used to find measured values that represent the shape of a workpiece. The shape of the workpiece is determined by an iterative method using the measured values.

Claims

1. Method for determining the shape of a workpiece, comprising the following steps:

a) measured values representing the shape of the workpiece are determined and stored by use of a measuring sensor;

b) approximate values representing the shape of the workpiece are determined;

c) modeled measured values are calculated using the approximate values;

d) the measured values found by use of the measuring sensor are compared to the modeled measured values and difference values are calculated;

e) new approximate values are calculated from the difference values for an optimized approximation to the shape of the workpiece;

f) steps c) through e) are iterated until a termination condition is met; and

g) the approximate values in effect when the terminating condition is met are stored as the shape of the workpiece.

2. Method according to claim 1, wherein the shape of the workpiece is determined during a machining process, in particular a grinding process.

3. Method according to claim 1, wherein the shape of a pin is determined, especially a crankpin for a crankshaft.

4. Method according to claim 3, wherein during the measuring process the pin performs an orbital rotation about a rotational axis that is parallel to the pin axis.

5. Method according to claim 1, wherein a measuring prism is used that is arranged on the measuring sensor.

6. Method according to claim 1, wherein a linearly movable measuring sensor is used.

7. Method according to claim 3, wherein in step a) the measured values are found as a function of the angular position of the pin.

8. Method according to claim 1, wherein step d) includes the following substeps:

d1) calculation of correction values from the difference values; and

d2) correction of the approximate values using the correction values.

9. Method according to claim 8, wherein the correction values are added to the approximate values in step d2).

10. Method according to claim 9, wherein a damping factor is taken into account when the correction values are added to the approximate values.

11. Method according to claim 1, wherein a limiting value for at least one difference value is used for a termination condition in step f).

12. Method according to claim 11, wherein the standard deviation for the difference values is compared to a limiting value.