Determining part orientation for incremental sheet forming

Patent metadata

Field	Value
Publication number	US-9676019-B2
Application number	US-201313916776-A
Country	US
Kind code	B2
Filing date	Jun 13, 2013
Priority date	Jun 13, 2013
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

Provided are methods and systems of orienting parts for incremental sheet forming and, in some examples, forming the parts in these orientations. A forming orientation may be identified by simulating forming operations of the same part in multiple different orientations and identifying the thinnest portions of the part for each of the orientations. The orientation with the maximum thickness of these identified portions is selected as a forming orientation. The forming simulation may be based on the Sine law by comparing the actual and projected areas of different surface elements of the shape to be formed. As such, a part formed in the forming orientation will have the greatest minimum thickness among all other possible orientations.

First claim

What is claimed is:

1. A method of orienting a part to be formed from a blank sheet relative to a virtual plane parallel to the blank sheet, the part to be formed from the blank sheet by incremental sheet forming using a stylus perpendicular to the virtual plane, the method comprising:
characterizing a shape of the part; and
identifying, relative to the virtual plane, a forming orientation of the part from a plurality of orientations,
wherein a thickness of a thinnest portion of the part is at a maximum when the part is formed in the forming orientation compared to the thickness of the thinnest portion of the part when the part is formed in any of the plurality of orientations other than the forming orientation, and
wherein identifying the forming orientation comprises:
(i) approximating the shape with surface elements, wherein the shape approximated with the surface elements is in one of the plurality of orientations relative to the virtual plane;
(ii) calculating an actual area of each of the surface elements;
(iii) calculating a projected area of each of the surface elements,
wherein the projected area is a normal projection of each of the surface elements onto the virtual plane;

(iv) identifying, among the surface elements, a specific surface element having a smallest ratio of the projected area to the actual area;
(v) reorienting the shape, approximated with the surface elements, into another one of the plurality of orientations relative to the virtual plane;
(vi) repeating (iii)-(v) for each of the plurality of orientations; and
(vii) selecting from the plurality of orientations, the forming orientation,
wherein the specific surface element, associated with the forming orientation, has a highest value of the smallest ratio of the projected area to the actual area of the specific surface element, associated with any other orientation of the plurality of orientations.

2. The method of claim 1 , wherein identifying the forming orientation comprises identifying an angle of rotation of the part relative to an axis in the virtual plane.

3. The method of claim 1 , wherein identifying the forming orientation comprises identifying a first angle of rotation of the part relative to a first axis in the virtual plane and identifying a second angle of rotation of the part relative to a second axis in the virtual plane.

4. The method of claim 1 , wherein approximating the shape comprises approximating the shape with flat triangular surface elements.

5. The method of claim 1 , wherein approximating the shape comprises one of a tessellation or a surface meshing.

6. The method of claim 1 , wherein reorienting the shape relative to the virtual plane comprises rotating the shape around an axis in the virtual plane.

7. The method of claim 1 , wherein reorienting the shape relative to the virtual plane further comprises rotating the shape around a first axis in the virtual plane and around a second axis in the virtual plane.

8. The method of claim 7 , wherein each of the plurality of orientations comprises a first angle of the shape relative to the first axis and a second angle of the shape relative to the second axis.

9. The method of claim 1 , wherein reorienting the shape relative to the virtual plane is controlled by a global search algorithm.

10. The method of claim 1 , wherein calculating the projected area of each of the surface elements after reorienting the shape approximated with the surface elements into the other one of the plurality of orientations relative to the virtual plane comprises determining coordinates of each of the surface elements for the other one of the plurality of orientations.

11. The method of claim 10 , wherein determining the coordinates of the surface elements after reorienting the shape comprises matrix multiplication of the coordinates of the surface elements before reorienting the shape.

12. The method of claim 1 , wherein repeating (iii)-(v) for each of the plurality of orientations comprises applying a global search algorithm.

13. The method of claim 1 , further comprising calculating a minimum thickness of the part to be formed corresponding to the smallest ratio for each of the plurality of orientations.

14. The method of claim 1 , further comprising fabricating a die for positioning the part in the forming orientation during forming of the blank sheet.

15. The method of claim 1 , further comprising forming the blank sheet into the part, wherein the part is in the forming orientation.

16. The method of claim 15 , wherein forming the blank sheet into the part with the part being in the forming orientation comprises one of two-point incremental forming or single-point incremental forming.

17. The method of claim 1 , wherein identifying the forming orientation comprises determining a thickness profile of the part in each of the plurality of orientations and identifying a minimal thickness in the thickness profile of the part in each of the plurality of orientations.

18. A computer system for orienting a part to be formed from a blank sheet relative to a virtual plane parallel to the blank sheet, the part to be formed from the blank sheet by incremental sheet forming using a stylus perpendicular to the virtual plane, the computer system comprising:
a memory configured to store a characterization of a shape of the part to be formed from the blank sheet; and
a processor configured to identify, relative to the virtual plane, a forming orientation of the part from a plurality of orientations,
wherein a thickness of a thinnest portion of the part is at a maximum when the part is formed in the forming orientation compared to the thickness of the thinnest portion of the part when the part is formed in any of the plurality of orientations other than the forming orientation, and
wherein identifying the forming orientation comprises:
(i) approximating the shape with surface elements, wherein the shape approximated with the surface elements is in one of the plurality of orientations relative to the virtual plane;
(ii) calculating an actual area of each of the surface elements;
(iii) calculating a projected area of each of the surface elements,
wherein the projected area is a normal projection of each of the surface elements onto the virtual plane;

(iv) identifying, among the surface elements, a specific surface element having a smallest ratio of the projected area to the actual area;
(v) reorienting the shape, approximated with the surface elements, into another one of the plurality of orientations relative to the virtual plane;
(vi) repeating (iii)-(v) for each of the plurality of orientations; and
(vii) selecting, from the plurality of orientations, the forming orientation,
wherein the specific surface element, associated with the forming orientation, has a highest value of the smallest ratio of the projected area to the actual area of the specific surface element, associated with any other orientation of the plurality of orientations.

19. A computer system for orienting a part to be formed from a blank sheet relative to a virtual plane parallel to the blank sheet, the part to be formed from the blank sheet by incremental sheet forming using a stylus perpendicular to the virtual plane, the computer system comprising:
means for characterizing a shape of the part to be formed from a blank sheet that is parallel to a virtual plane; and
means for identifying, relative to the virtual plane a forming orientation of the part from a plurality of orientations,
wherein a thickness of a thinnest port

Assignees

• Boeing Co

Inventors

• Elford Michael C

Classifications

• B29C51/46 Primary

  Measuring, controlling or regulating · CPC title

• G06T19/00

  Manipulating three-dimensional [3D] models or images for computer graphics · CPC title

• B21D31/005

  Incremental shaping or bending, e.g. stepwise moving a shaping tool along the surface of the workpiece (B21D22/14 takes precedence) · CPC title

• B29C51/30

  Moulds · CPC title

• B21D22/20 Primary

  Deep-drawing (special deep-drawing arrangements in, or in connection with, presses B21D24/00) · CPC title