CNC machine thermal growth characterization and thermal compensation correction

Patent metadata

Field	Value
Publication number	US-10088826-B2
Application number	US-201414463988-A
Country	US
Kind code	B2
Filing date	Aug 20, 2014
Priority date	Aug 20, 2014
Publication date	Oct 2, 2018
Grant date	Oct 2, 2018

Abstract

In at least one embodiment, a method of analyzing and characterizing the thermal growth of a CNC machine is provided. The method may include mounting an artifact having a bore onto a CNC machine and performing a test cycle. The test cycle may include probing the bore of the artifact to determine its location relative to the CNC machine and performing a dry cycle including one or more CNC machining processes. The method may further include calculating a deviation of the bore location from a reference relative location between the bore and CNC machine. The method may be used to improve, troubleshoot, or assess the effectiveness of CNC machine thermal compensation mechanisms. The method may start at ambient temperature and include repeating test cycles until a steady state temperature is reached in the machine.

First claim

What is claimed is:

1. A method comprising:
mounting an artifact having a pre-existing bore onto a CNC machine including a spindle and probe and a thermal compensation mechanism;
operating the CNC machine;
determining, via a controller, a first location of the artifact bore relative to the spindle and probe at the start of operation of the CNC machine;
determining, via the controller, a second location of the artifact bore relative to the spindle and probe, when the thermal compensation mechanism is deactivated while the CNC machine continues to operate and a third location of the artifact bore relative to the spindle and probe, when the thermal compensation mechanism is activated while the CNC machine continues to operate;
calculating, via the controller, a first deviation of the second location from the first location and a second deviation of the third location from the first location; and
correcting, via the controller, the thermal compensation mechanism in response to the first and second deviations being each outside of an acceptable deviation.

2. The method of claim 1 , wherein the operating step includes increasing the temperature of the CNC machine.

3. The method of claim 1 further comprising measuring the temperature at one or more locations on the CNC machine.

4. The method of claim 1 , wherein the artifact includes at least two bores and the determining steps are carried out on each of the at least two bores.

5. The method of claim 4 , wherein the calculating step is carried out on each of the at least two bores.

6. A method comprising:
mounting an artifact having a pre-existing bore onto a CNC machine including a spindle and probe and a thermal compensation mechanism;
performing a test cycle of the CNC machine, including:
probing the artifact bore to determine a first location relative to the spindle and probe;
probing the artifact bore to determine a second location relative to the spindle and probe, when the thermal compensation mechanism is deactivated, a third location relative to the spindle and probe, when the thermal compensation mechanism is activated; and
performing a dry cycle of the CNC machine including one or more CNC machining processes; and

calculating, via a controller, a first deviation of the second location from the first location and a second deviation of the third location from the first location; and
correcting, via a controller, the thermal compensation mechanism in response to the first and second deviations being outside of an acceptable deviation.

7. The method of claim 6 further comprising repeating the test cycle one or more times and performing the calculating step for each test cycle.

8. The method of claim 6 further comprising monitoring a temperature of at least one location on the CNC machine and comparing a temperature of the at least one location at a second time, t 2 , to a temperature at a first time, t 1 .

9. The method of claim 8 , wherein if a difference between the temperature at t 2 and the temperature at t 1 is more than a predetermined value then an additional test cycle is performed.

10. The method of claim 9 , wherein the predetermined value is from 0.5 to 5.0° C.

11. The method of claim 8 , wherein test cycles are repeated for at least a minimum time and for up to a maximum time, regardless of a difference between the temperatures at t 2 and t 1 .

12. The method of claim 6 , wherein the dry cycle includes a drilling or milling process.

13. The method of claim 6 , wherein the dry cycle further includes a tool change.

14. The method of claim 6 , wherein the CNC machine is at ambient temperature prior to a first test cycle.

15. A non-transitory computer readable storage medium, storing instructions that, when executed by a computer, causes the computer to execute the following function:
receiving information from a CNC machine including a spindle and probe and a thermal compensation mechanism regarding a first location of an artifact bore relative to the spindle and probe, a second location of the artifact bore relative to the spindle and probe, when the thermal compensation mechanism is deactivated during operation of the CNC machine, and a third location of the artifact bore relative to the spindle and probe, when the thermal compensation mechanism is activated while the CNC machine continues to operate; and
calculating a first deviation of the second location from the first location and a second deviation of the third location from the first location; and
correcting the thermal compensation mechanism in response to the first and second deviations being each outside of an acceptable deviation.

16. The non-transitory computer readable storage medium of claim 15 , wherein the instructions, when executed by the computer, cause the computer to execute the following further function: operating the CNC machine to increase the temperature from T 1 to T 2 .

17. The non-transitory computer readable storage medium of claim 15 , wherein the instructions, when executed by the computer, cause the computer to execute the following further function: measuring the temperature at one or more locations on the CNC machine.

18. The non-transitory computer readable storage medium of claim 15 , wherein the acceptable deviation is 10 μm.

19. The non-transitory computer readable storage medium of claim 15 , wherein the acceptable deviation is 5 μm.

20. The non-transitory computer readable storage medium of claim 15 , wherein the instructions, when executed by the computer, cause the computer to execute the following further function: monitoring a temperature of at least one location on the CNC machine and comparing a temperature of the at least one location at a second time, t 2 , to a temperature at a first time, t 1 .

Assignees

• Ford Global Tech Llc

Inventors

• Jalluri Chandra Sekhar
• Dilley David Norman
• Hill Trevor Leroi
• Sebastian Amando Jose
• Goderis Mark

Classifications

• B23Q17/00

  Arrangements for {observing,} indicating or measuring on machine tools (for automatic control or regulation of feed movement, cutting velocity or position of tool or work B23Q15/00) · CPC title

• B23Q23/00

  Arrangements for compensating for irregularities or wear, e.g. of ways, of setting mechanisms (automatic control B23Q15/00) · CPC title

• G05B19/401 Primary

  characterised by control arrangements for measuring, e.g. calibration and initialisation, measuring workpiece for machining purposes (G05B19/19 takes precedence) · CPC title

• G05B2219/49169

  Compensation for temperature, bending of tool · CPC title

• G01K5/48

  the material being a solid · CPC title