Utilization of CNC machining in composite part rework

Patent metadata

Field	Value
Publication number	US-11865647-B2
Application number	US-202016818825-A
Country	US
Kind code	B2
Filing date	Mar 13, 2020
Priority date	Mar 13, 2020
Publication date	Jan 9, 2024
Grant date	Jan 9, 2024

Abstract

A method for repairing a composite structure is provided. A rework zone is defined on the composite structure. A theoretical scarfing bottom surface is identified for the rework zone from a model of the composite structure. An actual scarfing bottom surface in a local axis system is identified for the rework zone. Parameters for a rework program for an automated scarfing tool are modified based on deviations between the theoretical scarfing bottom surface and the actual scarfing bottom surface. Plies in the rework zone are removed using the automated scarfing tool.

First claim

What is claimed is:

1. A method for repairing a composite structure, the method comprising:
defining a rework zone on the composite structure;
identifying a rectangular shaped theoretical scarfing bottom surface for the rework zone from a model of the composite structure;
selecting a scarf repair model based on a maximum longitudinal distance between two extremities of the composite structure and an aspect ratio of the rework zone, wherein the aspect ratio of the rework zone is a ratio of a width of a longitudinal edge of the rework zone and the maximum longitudinal distance between the two extremities of the composite structure;
identifying an actual scarfing bottom surface in a local axis system for the rework zone;
modifying parameters for a rework program for an automated scarfing tool based on deviations between the theoretical scarfing bottom surface and the actual scarfing bottom surface; and
removing plies in the rework zone using the automated scarfing tool.

2. The method of claim 1 , wherein identifying the actual scarfing bottom surface comprises:
transforming a theoretical rework program for the theoretical scarfing bottom surface from a global axis system to the local axis system in the rework zone; and
identifying the deviations between the theoretical scarfing bottom surface and the actual scarfing bottom surface.

3. The method of claim 2 , wherein identifying the deviations comprises:
cutting reference lines on a tool side surface of the composite structure parallel to all four edges of the theoretical scarfing bottom surface until all four of the edges are cut at a same depth.

4. The method of claim 3 , wherein identifying the deviations comprises:
rotating a cutting plane of the automated scarfing tool about the local axis system until all four of the edges are marked such that the cutting plane is parallel to a tool side surface of the composite structure.

5. The method of claim 4 , wherein identifying the deviations further comprises:
translating the cutting plane of the automated scarfing tool about the local axis system until all four of the edges are marked such that the cutting plane is parallel to the tool side surface of the composite structure.

6. The method of claim 5 , wherein modifying the parameters comprises:
transforming the modified theoretical rework program from the local axis system to the global axis system to create an actual rework program.

7. The method of claim 1 further comprising:
identifying a defect in the composite structure; and
defining the rework zone based on features of the defect.

8. The method of claim 1 , wherein when the aspect ratio is equal to or smaller than 1:10, a first scarf repair model is selected and wherein when the aspect ratio is larger than 1:10, a second scarf repair model is selected.

9. The method of claim 1 , wherein removing the plies comprises:
removing the plies with the automated scarfing tool in a 30:1-60:1 tapered ratio.

10. The method of claim 8 , wherein the second scarf model is selected, the method further comprising:
separating the rework zone into sections; and
modifying the parameters of the rework program in each of the sections.

11. A composite repair system comprising:
an automated scarfing tool configured to remove plies in a rework zone of a composite structure;
a database comprising a model of the composite structure having a rectangular shaped theoretical scarfing bottom surface;
a computer system configured to select a scarf repair model based on a maximum longitudinal distance between two extremities of the composite structure and an aspect ratio of the rework zone, wherein the aspect ratio of the rework zone is a ratio of a width of a longitudinal edge of the rework zone and the maximum longitudinal distance between the two extremities of the composite structure; and
the computer system further configured to identify an actual scarfing bottom surface in a local axis system for the rework zone and modify parameters for a rework program for the automated scarfing tool based on deviations between the theoretical scarfing bottom surface and the actual scarfing bottom surface;
wherein the automated scarfing tool is further configured to cut reference lines on a tool side surface of the composite structure parallel to all four edges of the theoretical scarfing bottom surface until all four of the edges are cut at a same depth.

12. The composite repair system of claim 11 further comprising:
an inspection system configured to identify a defect in the composite structure.

13. The composite repair system of claim 11 further comprising:
a controller configured to control movement of the automated scarfing tool such that the controller can adjust a cutting plane for the automated scarfing tool by rotating the automated scarfing tool and translating the automated scarfing tool along the local axis system until the cutting plane is parallel to the actual scarfing bottom surface.

14. The composite repair system of claim 11 further comprising:
a measurement system configured to measure reference locations in the rework zone.

15. The composite repair system of claim 11 further comprising:
a vision system configured to collect image data for the rework zone.

16. A method for repairing a composite structure, the method comprising:
defining a rework zone on the composite structure;
selecting a scarf repair model based on a maximum longitudinal distance between two extremities of the composite structure and an aspect ratio of the rework zone, wherein the aspect ratio of the rework zone is a ratio of a width of a longitudinal edge of the rework zone and the maximum longitudinal distance between the two extremities of the composite structure;
separating the rework zone into sections;
identifying a theoretical scarfing bottom surface for each of the sections of the rework zone from a model of the composite structure;
measuring reference locations in each of the sections of the rework zone;
identifying an actual scarfing bottom surface for each of the sections of the rework zone based on measurements collected at the reference locations;
modifying parameters for a rework program for an automated scarfing tool based on deviations between the measurements collected at the reference locations; and
removing plies in each of the sections of the rework zone using the automated scarfing tool.

17. The method of claim 16 further comprising:
separating the rework zone into the sections based on a determination that the aspect ratio is greater than 1:10.

18. The method of claim 16 , wherein measuring the reference locations comprises:
cutting a primary reference location in each of the sections of the rework zone;
probing the primary reference location to determine the actual scarfing bottom surface in each of the sections; and
modifying a tool path for the rework program based on the deviations between the actual scarfing bottom surface and the theoretical scarfing bottom surface.

19. The method of claim 18 , wherein measuring the reference locations further comprises:
cutting a number of secondary reference locations in each of the sections of the rework zone;
probing the number of secondary reference locations to determine the deviations caused by the automated scarfing tool; and
modifying the tool path for the automated scarfing tool based on the deviations in measurement between the number of secondary reference locations.

20. The method of claim 16 further comprising:
identi

Assignees

• Boeing Co

Inventors

• Zhang Hongda
• Chung Yee-Ying
• Dysievick Steven
• Forster Michael Victor

Classifications

• B23K7/06 Primary

  Machines, apparatus or equipment specially designed for scarfing or desurfacing · CPC title

• B23Q15/26

  of angular position · CPC title

• B23Q17/20

  for indicating or measuring workpiece characteristics, e.g. contour, dimension, hardness · CPC title

• B23Q17/2471

  of workpieces · 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