Methods and systems for determining and displaying a time to overload of machine tools

• US 8,294,403 B2
• Filed: 09/04/2009
• Issued: 10/23/2012
• Est. Priority Date: 09/04/2009
• Status: Active Grant

• Current Assignee: HAAS Automation Incorporated
• Original Assignee: HAAS Automation Incorporated
• Inventors: Haas, Gene F., Zierhut, Kurt P.
• Primary Examiner(s): Ro, Bentsu
• Application Number:
  US12/554,847
• Publication Number:
  US 20110057594A1
• Time in Patent Office: 1,145 Days
• Field of Search: 318432-434, 318456-458, 318471-473, 318/490
• US Class Current: 318/473
• CPC Class Codes: G05B 19/406 characterised by monitoring or safety G05B19/19 takes precedence
• CPC Class Codes: G05B 2219/37342 Overload of motor, tool

Abstract

Systems and methods for determining and displaying a time to overload of a motor in a computer numerical controlled (CNC) machine tool are provided. A method includes monitoring a fuse level of a motor in a CNC machine tool and calculating a time to overload of the motor based on the fuse level. The method further includes displaying the time to overload on a user interface based on the fuse level of the motor and a load acting on the motor.

Claims

1. A method for determining a time to overload of a motor in a computer numerical controlled (CNC) machine tool, comprising:

monitoring a fuse level of a motor in a CNC machine tool;

calculating a time to overload of the motor based on the fuse level; and

displaying the time to overload on a user interface based on the fuse level of the motor and a load acting on the motor.

2. The method of claim 1, wherein monitoring the fuse level of the motor comprises:

determining a present fuse level of the motor;

calculating a fuse level difference between the present fuse level and a previous fuse level of the motor;

calculating a time period between determining the present fuse level and determining the previous fuse level; and

calculating a rate of change of the fuse level based on the fuse level difference and the time period.

3. The method of claim 2, wherein the time to overload of the motor based on the fuse level is calculated if the rate of change is not zero and if the present fuse level is lower than a limiting fuse level of the motor.

4. The method of claim 1,

wherein displaying the time to overload on the user interface based on the fuse level and the load acting on the motor comprises:

determining if the load acting on the motor is decreasing; and

displaying the time to overload if the time to overload is within an operator selected time frame, if the fuse level is lower than a limiting fuse level of the motor, and if the load is not decreasing.

5. The method of claim 1, wherein the fuse level of the motor is based on a maximum continuous current rating of the motor, a time constant of the motor, and an input current to the motor.

6. The method of claim 1, further comprising repeating the monitoring step, the calculating step, and the displaying step at a set time interval.

7. A computer numerical controlled (CNC) machine tool comprising:

a motor;

a controller configured to monitor a fuse level of the motor in a CNC machine tool and calculate a time to overload of the motor based on the fuse level; and

a user interface configured to display the time to overload based on the fuse level of the motor and a load acting on the motor.

8. The CNC machine tool of claim 7, wherein the controller is further configured to determine a present fuse level of the motor, calculate a fuse level difference between the present fuse level and a previous fuse level of the motor, calculate a time period between determining the present fuse level and determining the previous fuse level, and calculate a rate of change of the fuse level based on the fuse level difference and the time period.

9. The CNC machine tool of claim 8, wherein the controller is further configured to calculate the time to overload of the motor if the rate of change is not zero and if the present fuse level is lower than a limiting fuse level of the motor.

10. The CNC machine tool of claim 7, wherein the controller is further configured to determine if the load acting on the motor is decreasing, and wherein the user interface is further configured to display the time to overload if the time to overload is within an operator selected time frame, if the fuse level is lower than a limiting fuse level of the motor, and if the load is not decreasing.

11. The CNC machine tool of claim 7, wherein the fuse level of the motor is based on a maximum continuous current rating of the motor, a time constant of the motor, and an input current to the motor.

12. The CNC machine tool of claim 7, wherein the controller is further configured to repeat monitoring the fuse level of the motor and calculating the time to overload of the motor at a set time interval, and wherein the user interface is further configured to repeat displaying the time to overload at the set time interval.

13. A controller for a computer numerical controlled (CNC) machine tool, comprising:

a user interface;

a memory module containing executable instructions; and

a processor configured to execute the instructions to perform a method for;

monitoring a fuse level of a motor in a CNC machine tool;

calculating a time to overload of the motor based on the fuse level; and

displaying the time to overload on the user interface based on the fuse level of the motor and a load acting on the motor.

14. The controller of claim 13, wherein monitoring the fuse level of the motor comprises:

determining a present fuse level of the motor;

calculating a fuse level difference between the present fuse level and a previous fuse level of the motor;

calculating a time period between determining the present fuse level and determining the previous fuse level; and

calculating a rate of change of the fuse level based on the fuse level difference and the time period.

15. The controller of claim 14, wherein the time to overload of the motor based on the fuse level is calculated if the rate of change is not zero and if the present fuse level is lower than a limiting fuse level of the motor.

16. The controller of claim 13,

wherein displaying the time to overload on the user interface based on the fuse level and the load acting on the motor comprises:

determining if the load acting on the motor is decreasing; and

displaying the time to overload if the time to overload is within an operator selected time frame, if the fuse level is lower than a limiting fuse level of the motor, and if the load is not decreasing.

17. The controller of claim 13, wherein the fuse level of the motor is based on a maximum continuous current rating of the motor, a time constant of the motor, and an input current to the motor.

18. The controller of claim 13, wherein the method further comprises repeating the monitoring step, the calculating step, and the displaying step at a set time interval.

19. A machine-readable medium encoded with executable instructions for determining a time to overload of a motor in a computer numerical controlled (CNC) machine tool, the instructions comprising code for:

monitoring a fuse level of a motor in a CNC machine tool;

calculating a time to overload of the motor based on the fuse level; and

displaying the time to overload on a user interface based on the fuse level of the motor and a load acting on the motor.

20. The machine-readable medium of claim 19, wherein monitoring the fuse level of the motor comprises:

determining a present fuse level of the motor;

calculating a fuse level difference between the present fuse level and a previous fuse level of the motor;

calculating a time period between determining the present fuse level and determining the previous fuse level; and

calculating a rate of change of the fuse level based on the fuse level difference and the time period.

21. The machine-readable medium of claim 20, wherein the time to overload of the motor based on the fuse level is calculated if the rate of change is not zero and if the present fuse level is lower than a limiting fuse level of the motor.

22. The machine-readable medium of claim 19,

wherein displaying the time to overload on the user interface based on the fuse level and the load acting on the motor comprises:

determining if the load acting on the motor is decreasing; and

displaying the time to overload if the time to overload is within an operator selected time frame, if the fuse level is lower than a limiting fuse level of the motor, and if the load is not decreasing.

23. The machine-readable medium of claim 19, wherein the fuse level of the motor is based on a maximum continuous current rating of the motor, a time constant of the motor, and an input current to the motor.

24. The machine-readable medium of claim 19, wherein the instructions further comprise code for repeating the monitoring code, the calculating code, and the displaying code at a set time interval.