LASER ASSISTED MACHINING SYSTEM FOR CERAMICS AND HARD MATERIALS

• US 20150105899A1
• Filed: 12/22/2014
• Published: 04/16/2015
• Est. Priority Date: 11/30/2011
• Status: Active Application

• Current Assignee: Board of Regents for Northern Illinois University
• Original Assignee: Board of Regents for Northern Illinois University
• Inventors: Santner, Joseph S., Sciammarella, Federico M., Kyselica, Stefan
• Granted Patent: US 10,279,444 B2
• Time in Patent Office: Days
• US Class Current: 700/166
• CPC Class Codes: B23K 26/0093 combined with mechanical machining or metal-working covered by other subclasses than B23K combined welding or cutting procedures or apparatus B23K28/02
• CPC Class Codes: B23P 25/006 Heating the workpiece by laser during machining
• CPC Class Codes: G05B 19/182 characterised by the machine tool function, e.g. thread cutting, cam making, tool direction control G05B19/21 - G05B19/40 take precedence
• CPC Class Codes: G05B 2219/45165 Laser machining

Abstract

An improved apparatus and method for laser assisted machining are provided, by utilizing a computer to develop interrelated heating and machining plans, from a variety of input data describing the material to be machined, the properties of lasers and pyrometers used for heating the material, and computer models of the machining arrangement, workpiece and final part to be produced. An iterative process continues until the machining and heating plans result in the cutting zone of the workpiece being maintained at a desired temperature with no obstruction in the line-of-sight of at least one laser and pyrometer throughout the machining process, while also maintaining the cutting tool at or below a desired maximum temperature.

Claims

1. A method for Laser Assisted Machining (LAM) of a finished part from a workpiece mounted in a machining arrangement, according to a machining process, using a cutter of the machining arrangement for removing material from the workpiece along a cutting path including a cutting zone of the workpiece ahead of the cutter where the cutting zone is heated to a desired machining temperature by a laser heating arrangement having one or more lasers operatively disposed for heating the cutting zone and at least one pyrometer arrangement for detecting a temperature of the cutting zone, the method comprising:

inputting into a controller, dynamic computer models in machine readable format for the workpiece, the finished part, the machining arrangement, and the laser heating arrangement, the dynamic computer models all being related to a common reference system, describing the physical shape and all potential movement and orientation of the models with respect to the common reference system;

inputting material property data in machine readable format into the computer for the workpiece and machining arrangement, including thermal and optical material properties of the workpiece and desired machining temperature data;

inputting laser and pyrometer operating parameters for the laser heating arrangement in machine readable format into the controller, with the laser operating parameters including input and output power, line-of-sight coordinates and beam configuration parameters for each laser of the one or more lasers, and the pyrometer operating parameters including input and output operating parameters of the pyrometer arrangement;

using the controller to generate a recommended machining plan including a cutting path for the cutter and movement and orientation of the models of the workpiece, the finished part and the machining arrangement during machining of the finished part from the workpiece;

using the controller to generate a recommended heating plan for the laser heating arrangement from the recommended machining plan, to heat the cutting zone with the one or more lasers and monitor the temperature of the cutting zone with the pyrometer arrangement, with the recommended heating plan including movement and orientation of the model of the laser heating arrangement during machining of the finished part from the workpiece;

using the computer to verify that the cutting zone of the workpiece is maintained at the desired machining temperature during the recommended machining plan;

using the computer to verify that the one or more lasers and the one or more pyrometers utilized in the recommended heating plan have an unobstructed line-of-site from their location to the cutting zone throughout the recommended machining plan;

iterating the above method until the recommended machining and heating plans result in the cutting zone being maintained at the desired temperature with no obstruction of the line-of-sight throughout the machining process; and

machining the workpiece in accordance with the recommended machining and heating plans if the controller verifies that the cutting zone is maintained at the desired temperature and the line-of-sight is not obstructed throughout the machining process.

2. The method of claim 1, further comprising, iterating at least one of the recommended machining and heating plans to achieve at least one desired aspect of the method from the group of desired aspects consisting of:

number of lasers used for heating;

number of pyrometers used for measurement of temperature of the cutting zone;

degrees of freedom of movement and orientation afforded the machining arrangement;

degrees of freedom of movement and orientation afforded one or more of the one or more lasers;

degrees of freedom of movement and orientation of one or more of the one or more pyrometer arrangements;

a desired surface finish of the finished part;

a desired tolerance range for a dimension of the finished part;

a desired temperature range for the cutting zone;

a desired shape of the cutting zone;

a desired depth of heating for the cutting zone;

a desired power input to the heating arrangement;

a desired power output of the heating arrangement;

cutting feeds and speed, cutter shape;

cutter movement.

3. The method of claim 1, wherein, at least one of the recommended heating and machining plans comprises, an adjustment to at least one of the machining and heating plans during the machining process.

4. The method of claim 3, wherein, the controller makes the adjustment to at least one of the machining and heating plans during the machining process “

on-the-fly”

as the machining process continues uninterrupted.

5. The method of claim 3, wherein, at least one of the recommended heating and machining plans comprises:

stopping the machining process at least once so that the controller can make the adjustment to at least one of the machining and heating plans while the machining process is stopped; and

then resuming the machining process according to the recommended plans.

6. The method of claim 3, wherein, the adjustment to at least one of the recommended machining and heating plans includes one or more adjustments from the group of adjustments consisting of:

changing the cutter;

changing the number of lasers;

re-positioning the workpiece.

7. The method of claim 6, wherein, the controller makes the adjustment to at least one of the machining and heating plans during the machining process “

on-the-fly”

as the machining process continues uninterrupted.

8. The method of claim 6, wherein, the recommended plan comprises:

stopping the machining process at least once so that the controller can make the adjustment to at least one of the machining and heating plans while the machining process is stopped; and

then resuming the machining process according to the recommended plans.

9. A controller-readable medium having computer executable instructions for performing the steps of a method for Laser Assisted Machining (LAM) of a finished part from a workpiece mounted in a machining arrangement, according to a machining process, using a cutter of the machining arrangement for removing material from the workpiece along a cutting path including a cutting zone of the workpiece ahead of the cutter where the cutting zone is heated to a desired machining temperature by a laser heating arrangement having one or more lasers operatively disposed for heating the cutting zone and at least one pyrometer arrangement for detecting a temperature of the cutting zone, wherein the method comprises:

inputting into a computer, dynamic computer models in machine readable format for the workpiece, the finished part, the machining arrangement, and the laser heating arrangement, the dynamic computer models all being related to a common reference system, describing the physical shape and all potential movement and orientation of the models with respect to the common reference system;

inputting material property data in machine readable format into the computer for the workpiece and machining arrangement, including thermal and optical material properties of the workpiece and desired machining temperature data;

inputting laser and pyrometer operating parameters for the laser heating arrangement in machine readable format into the computer, with the laser operating parameters including input and output power, line-of-sight coordinates and beam configuration parameters for each laser of the one or more lasers, and the pyrometer operating parameters including input and output operating parameters of the pyrometer arrangement;

using the computer to generate a recommended machining plan including the cutting path and movement and orientation of the models of the workpiece, the finished part and the machining arrangement during machining of the finished part from the workpiece;

using the computer to generate a recommended heating plan for the laser heating arrangement from the recommended machining plan, to heat the cutting zone with the one or more lasers and monitor the temperature of the cutting zone with the pyrometer arrangement, with the recommended heating plan including movement and orientation of the model of the laser heating arrangement during machining of the finished part from the workpiece;

using the controller to verify that the cutting zone of the workpiece is maintained at the desired machining temperature during the recommended machining plan;

using the controller to verify that the one or more lasers and the one or more pyrometers utilized in the recommended heating plan have an unobstructed line-of-site from their location to the cutting zone throughout the recommended machining plan;

iterating the above method until the recommended machining and heating plans result in the cutting zone being maintained at the desired temperature with no obstruction of the line-of-sight throughout the machining process; and

then machining the workpiece in accordance with the recommended machining and heating plans if the controller verifies that the cutting zone is maintained at the desired temperature and the line-of-sight is not obstructed throughout the machining process.

10. The computer readable medium of claim 9, wherein the method further comprises, the step of iterating at least one of the recommended machining and heating plans to achieve at least one desired aspect of the method from the group of desired aspects consisting of:

number of lasers used for heating;

number of pyrometers used for measurement of temperature of the cutting zone;

degrees of freedom of movement and orientation afforded the machining arrangement;

degrees of freedom of movement and orientation afforded one or more of the one or more lasers;

degrees of freedom of movement and orientation of one or more of the one or more pyrometer arrangements;

a desired surface finish of the finished part;

a desired tolerance range for a dimension of the finished part;

a desired temperature range for the cutting zone;

a desired shape of the cutting zone;

a desired depth of heating for the cutting zone;

a desired power input to the heating arrangement;

a desired power output of the heating arrangement;

cutting feeds and speed, cutter shape;

cutter movement.

11. The controller readable medium of claim 9, wherein, at least one of the recommended heating and machining plans comprises an adjustment to at least one of the machining and heating plans during the machining process and the method further comprises the step of performing the adjustment.

12. The controller readable medium of claim 11, wherein, the method further causes the controller to make the adjustment to the at least one of the machining and heating plans during the machining process “

on-the-fly”

as the machining process continues uninterrupted.

13. The controller readable medium of claim 11, wherein:

at least one of the recommended heating and machining plans of the method comprises, stopping the machining process at least once so that the controller can make the adjustment to at least one of the machining and heating plans while the machining process is stopped, and then resuming the machining process according to the recommended plans; and

the controller executable instructions further include instructions for stopping the machining process, directing the controller to make the adjustment, and then restarting the machining process after the adjustment has been made by the controller.

14. The controller readable medium of claim 11, wherein, the adjustment to at least one of the recommended machining and heating plans includes one or more adjustments from the group of adjustments consisting of:

changing the cutter;

changing the number of lasers;

re-positioning the workpiece.

15. The controller readable medium of claim 14, wherein, the controller makes the adjustment to at least one of the machining and heating plans during the machining process “

on-the-fly”

as the machining process continues uninterrupted.

16. The controller readable medium of claim 14, wherein, the recommended plan comprises:

stopping the machining process at least once so that the controller can make the adjustment to at least one of the machining and heating plans while the machining process is stopped; and

then resuming the machining process according to the recommended plans.