Method of making coordinate measurements of a workpiece on a machine tool

• US 5,996,239 A
• Filed: 02/07/1997
• Issued: 12/07/1999
• Est. Priority Date: 02/07/1996
• Status: Expired due to Fees

• Current Assignee: Carl-Zeiss-Stiftung
• Original Assignee: Carl-Zeiss-Stiftung
• Inventors: Ohnheiser, Rainer
• Primary Examiner(s): Gutierrez, Diego
• Assistant Examiner(s): SMITH, RICHARD A
• Application Number:
  US08/796,242
• Time in Patent Office: 1,033 Days
• Field of Search: 33/503, 33/1 M
• US Class Current: 33/503
• CPC Class Codes: G01B 21/04 by measuring coordinates of points
• CPC Class Codes: G01B 5/008 using coordinate measuring machines

Abstract

The invention is directed to a method for making coordinate measurements on a workpiece on a machine tool. In this method, the workpiece 25 remains on the machine tool during the measuring operation and is scanned via a measuring arm of a coordinate measuring apparatus 31 set up next to the machine tool 21. The coordinate measuring apparatus 31 has its own measuring system for detecting the movements of the measurement arm 34 or of the probe 35 attached to the measuring arm. It is not absolutely necessary that the coordinate measuring apparatus 21 have its own drives or that it has its own CNC-control because the measurement arm or the probe head can be guided or moved with the aid of an entrainment device 27 by the drives of the machine tool 21.

Claims

1. A method for making coordinate measurements of a workpiece on a machine tool with a coordinate measuring apparatus set up next to or on the machine tool, the apparatus having a measuring arm for holding a probe unit having a probe element and said apparatus having a measurement system including a plurality of sensors, the method comprising the steps of:

keeping the workpiece on the machine tool while mating the coordinate measurements;

moving said measuring arm to permit contact scanning the workpiece with the probe element of said probe unit;

utilizing said plurality of sensors for detecting the movements of said probe element and utilizing said measurement system of said coordinate measuring apparatus for making the coordinate measurement of said workpiece; and

,

said machine tool having a measurement system and said measurement system of said coordinate measuring apparatus being separate from said measurement system of said machine tool.

2. The method of claim 1, wherein the machine tool defines a machining space, the method comprising the further step of moving said measuring arm into the machining space of said machine tool.

3. The method of claim 2, wherein said machine tool has drives to move a worktool into said machining space;

the method comprises the further step of moving said measuring arm via said drives; and

, detecting the position of said probe unit with the measurement system of said coordinate measuring apparatus.

4. The method of claim 3, wherein said machine tool has a movable part;

and, wherein the method comprises the further step of coupling said measuring arm or said probe unit to said movable part.

5. The method of claim 4, wherein said machine tool has a control;

and, wherein the method comprises the further step of feeding said coordinate measurement to said control of said machine tool.

6. The method of claim 1, comprising the further step of moving said coordinate measuring apparatus in the direction of the machining space of said machine tool for the coordinate measurement.

7. The method of claim 1, wherein said measurement system of said machine tool has a predetermined measuring accuracy and said measurement system of said coordinate measuring apparatus having a measuring accuracy greater than said measuring accuracy of said measurement system of said machine tool.

8. A combined machining and measuring center for a workpiece, the center comprising:

a machine tool wherein the workpiece remains mounted thereon during a measuring operation thereof;

a coordinate measuring apparatus mounted next to or on said machine tool;

said apparatus having a movable measuring arm and a probe unit attached to said measuring arm;

said coordinate measuring apparatus having its own measuring system including a plurality of sensors for detecting the movements of said probe unit attached to said movable measuring arm to facilitate a coordinate measurement of said workpiece by said measuring system; and

said machine tool having a measurement system and said measuring system of said coordinate measuring apparatus being separate from said measurement system of said machine tool.

9. The center of claim 8, said machine tool having a movable part and said center further comprising a coupling device for coupling one of said measuring arm and said probe unit to said movable part.

10. The center of claim 9, said coupling device including an electromechanical, a magnetic or a pneumatic coupling which can be machine-control activated or manually activated.

11. The center of claim 8, wherein said coordinate measuring apparatus and said machine tool conjointly define a docking interface to permit said measuring arm to move into the machining space of said machine tool after said apparatus has been docked on said machine tool.

12. The center of claim 8, said measuring arm being an articulated arm having a plurality of articulated joints so as to permit said probe unit to be freely displaceable in at least two coordinates.

13. The center of claim 8, wherein said coordinate measuring apparatus is a stationary apparatus;

said measuring arm being a horizontally displaceable measuring arm; and

, said probe unit being attached to said measuring arm so as to be displaceable therewith.

14. The center of claim 8, said measuring arm being an articulated arm having a plurality of articulated joints so as to permit said probe unit to be freely displaceable in at least two coordinates.

15. The center of claim 8, wherein said measurement system of said machine tool has a predetermined measuring accuracy and said measuring system of said coordinate measuring apparatus having a measuring accuracy greater than said measuring accuracy of said measurement system of said machine tool.

16. A method for making coordinate measurements of a workpiece on a machine tool with a coordinate measuring apparatus set up next to or on the machine tool, the apparatus having a measuring arm for holding a probe unit having a probe element and the apparatus having a measurement system and the machine tool having drives to move a movable part, the method comprising the steps of:

keeping the workpiece on the machine tool while making the coordinate measurements;

coupling one of said measuring arm and said probe unit to said movable part;

moving said measuring arm via the drives of the machine tool to permit contact scanning of the workpiece with the probe element of said probe unit;

detecting the movements of said probe element for making the coordinate measurement utilizing said measurement system of said coordinate measuring apparatus; and

,

said machine tool having a measurement system and said measurement system of said coordinate measuring apparatus being separate from said measurement system of said machine tool.

17. The method of claim 16, wherein the machine tool defines a machine space, the method comprising the further step of moving said measuring arm into the machining space of said machine tool.

18. The method of claim 17, wherein the drives of said machine tool moves a worktool into said machining space;

the method comprises the further step of moving said measuring arm via said drives; and

, detecting the position of said probe unit with the measurement system of said coordinate measuring apparatus.

19. The method of claim 18, wherein said machine tool has a control;

and, wherein the method comprises the further step of feeding the obtained results of the coordinate measurement to said control of said machine tool.

20. The method of claim 16, comprising the further step of moving said coordinate measuring apparatus in the direction of the machining space of said machine tool for the coordinate measurement.

21. The method of claim 16, wherein said measurement system of said machine tool has a predetermined measuring accuracy and said measurement system of said coordinate measuring apparatus having a measuring accuracy greater than said measuring accuracy of said measurement system of said machine tool.

22. A combined machining and measuring center for a workpiece, the center comprising:

a machine tool wherein the workpiece remains mounted on the machine tool during a measuring operation thereof;

said machine tool having a movable part and drives to move said movable part,

a coordinate measuring apparatus mounted next to or on said machine tool;

said apparatus having a movable measuring arm and a probe unit attached to said measuring arm;

said coordinate measuring apparatus having its own measurement system for detecting the position of said probe attached to said movable measuring arm and for making coordinate measurements of said workpiece;

a coupling device for coupling one of said measuring arm and said probe unit to said movable part so as to permit said drives to said machine tool to move said measuring arm to facilitate making said coordinate measurements of said workpiece by utilizing said measurement system of said coordinate measuring apparatus; and

,

said machine tool having a measurement system and said measurement system of said coordinate measuring apparatus being separate from said measurement system of said machine tool.

23. The center of claim 22, said coupling device including an electromechanical, a magnetic or a pneumatic coupling which can be machine-control activated or manually activated.

24. The center of claim 22, wherein said coordinate measuring apparatus and said machine tool conjointly define a docking interface to permit said measuring arm to move into the machining space of said machine tool after said apparatus has been docked next to or on said machine tool.

25. The center of claim 22, wherein said coordinate measuring apparatus is a stationary apparatus;

said measuring arm being a horizontally displaceable measuring arm; and

, said probe unit being attached to said measuring arm so as to be displaceable therewith.

26. The center of claim 22, wherein said measurement system of said machine tool has a predetermined measuring accuracy and said measurement system of said coordinate measuring apparatus having a measuring accuracy greater than said measuring accuracy of said measurement system of said machine tool.