Multi-piece flexural pivot

• US 4,997,123 A
• Filed: 05/31/1990
• Issued: 03/05/1991
• Est. Priority Date: 05/31/1990
• Status: Expired due to Term

• Current Assignee: Goodrich Corporation (Rtx Corporation)
• Original Assignee: Lucas Aerospace Power Transmission Corporation (Rtx Corporation)
• Inventors: Backus, Robert O., Rhymestine, Richard R., Gupta, Subhash C., Salerno, Daniel J.
• Primary Examiner(s): HEINRICH, SAMUEL M
• Application Number:
  US07/531,292
• Time in Patent Office: 278 Days
• Field of Search: 228/182, 228/189, 228/254, 29/173, 29/436, 267/160, 403/220, 403/291, 464/51, 464/100
• US Class Current: 228/182
• CPC Class Codes: B23K 1/0008 specially adapted for particular articles or work
• CPC Class Codes: F16C 11/12 incorporating flexible connections, e.g. leaf springs
• CPC Class Codes: F16D 3/005 incorporating leaf springs, flexible parts of reduced thickness or the like acting as pivots
• CPC Class Codes: Y10T 29/49609 Spring making
• CPC Class Codes: Y10T 29/49844 Through resilient media

Abstract

A flexural pivot is configured as a multi-piece device which is specifically configured to tolerate vibration and shock loading. The flex pivot described uses pre-formed unitary (one-piece) support structures which have integral undercut areas, diametrically opposed slots for flexural member placement and key ways and the like, and near net shape geometry. The flexural members are pre-brazed to facilitate the assembly process. The design of the pre-formed support structures eliminates brazed joints which are common locations of fracture due to vibration and shock loading, resulting in a significantly strengthened pivot. The overall configuration and method described provides an economical flex pivot, whereby the flex pivots are accessible for applications which have not heretofore been feasible.

Claims

1. A method for fabricating a multi-piece flexural pivot comprising:

forming first and second support structures as unitary structures so that each of said unitary structures has an outer portion with a diametrical opening extending therethrough and a reduced diameter arcuate portion extending therefrom and a pair of diametrically opposed slots extending in the opening and in the arcuate portion;

applying a braze material to a strip of flexural material;

forming first and second flexural members from the flexural material having the braze material applied thereto so that said first flexural member has a solid center and said second flexural member has an open center;

inserting the solid center of the first flexural member in the open center of the second flexural member for providing a flexural assembly;

disposing the first and second unitary support structures so that the reduced diameter arcuate portion of the first structure extends in the diametrical opening of the second structure and the reduced diameter arcuate portion of the second structure extends in the diametrical opening of the first structure;

disposing the flexural assembly so that the first and second flexural members engage the diametrically opposed slots in the openings and in the arcuate portions of the first and second structures to provide a pivot assembly; and

exposing the pivot assembly to a thermal environment for brazing the flexural assembly in the diametrically opposed slots to provide a flexural pivot permitting relative pivotal displacement between the first and second support structures.

2. A method for fabricating a multi-piece flexural pivot as described by claim 1, wherein forming first and second support structures as unitary structures includes:

forming the first and second support structures so that said structures have near net shape geometry.

3. A method for fabricating a multi-piece flexural pivot as described by claim 2, wherein forming the first and second support structures so that said structures have near net shape geometry includes:

metal injection molding the support structures.

4. A method for fabricating a multi-piece flexural pivot as described by claim 1, wherein applying a braze material to a flexural material includes:

electroplating the braze material to a strip of flexural material.

5. A method for fabricating a multi-piece flexural pivot as described by claim 1, wherein forming first and second flexural members from the flexural material having the braze material applied thereto includes:

Stamping the first and second flexural members from a strip of flexural material having the braze material applied thereto.

6. A method for fabricating a multi-piece flexural pivot as described by claim 4, including:

stamping the first and second flexural members from a strip of flexural material having the braze material electroplated thereon.

7. A method for fabricating a multi-piece flexural pivot as described by claim 1, wherein forming the first and second support structures as unitary structures includes;

forming the diametrically opposed slots so that said slots are slightly wider than the thickness of the first and second flexural members for accommodating the increased thickness of said flexural members due to the application of the braze material.

8. A method for fabricating a multi-piece flexural pivot as described by claim 1, wherein exposing the pivot assembly to a thermal environment for brazing the flexural assembly in the diametrically opposed slots includes:

fixturing the pivot assembly; and

oven brazing the fixtured pivot assembly.

9. A method for fabricating a multi-piece flexural pivot as described by claim 5, wherein:

the oven brazing duration and temperature range are selected for heat treating the pivot assembly.

10. A method for manufacturing a multi-piece flexural pivot as described by claim 1, including:

filling the flexural pivot with a suitable material to prevent flexing; and

performing finishing operations on the filled flexural pivot to insure specified net geometry.

11. A method for fabricating a multi-piece flexural pivot comprising:

forming first and second support structures as unitary structures so that each of said first and second unitary structures has an outer portion with a diametrical opening extending therethrough and a reduced diameter arcuate portion extending therefrom, and a pair of diametrically opposed slots extending in the opening and in the arcuate portion;

forming a third structural support as a unitary structure having an outer portion with a diametrical opening extending therethrough and oppositely disposed reduced diameter arcuate portions extending therefrom, and having diametrically opposed slots extending in the arcuate portions;

applying a braze material to a flexural material;

forming first and second flexural members from the flexural material having the braze material applied thereto so that said first flexural member has a solid center and said second flexural member has an open center;

inserting the solid center of the first flexural member in the open center of the second flexural member for providing a flexural assembly;

disposing the first, second and third unitary support structures so that their reduced diameter arcuate portions extend in the diametrical opening of the third unitary support structure, and the oppositely disposed reduced diameter arcuate portions extending from said third unitary support structure extend in the diametrical openings of the first and second unitary support structures;

disposing the flexural assembly so that the first and second flexural members engage the diametrically opposed slots in the first, second and third unitary support structures to provide a pivot assembly; and

exposing the pivot assembly to a thermal environment for brazing the flexural assembly in the diametrically opposed slots to provide a flexural pivot permitting relative pivotal displacement between the first, second and third unitary support structures.

12. A method for fabricating a multi-piece flex pivot as described by claim 11, wherein forming the first, second and third support structures as unitary structures includes:

forming the first, second and third support structures so that said structures have near net shape geometry.

13. A method for fabricating a multi-piece flex pivot as described by claim 12, wherein forming the first, second and third support structures so that said structures have near net shape geometry includes:

metal injection molding the support structures.

14. A method for fabricating a multi-piece flexural pivot as described by claim 11, wherein forming first and second flexural members from the flexural material having the braze material applied thereto includes:

stamping the first and second flexural members from a strip of flexural material having the braze material applied thereto.

15. A method for fabricating a multi-piece flexural pivot comprising:

forming a plurality of support structures as unitary support structures so that each of said plurality of support structures has portions for mating with portions of the others of the plurality of support structures, and arranging said plurality of support structures for retaining a flexural assembly;

applying a braze material to a flexural material and forming a flexural assembly therefrom;

disposing the plurality of support structures so that the mating portions thereof mate;

disposing the flexural assembly having the brazed material applied thereto for retaining said assembly by the plurality of support structures and for providing a pivot assembly; and

exposing the pivot assembly to a thermal environment for brazing the flexural assembly to the plurality of support structures and for providing a flexural pivot permitting relative pivotal displacement between the plurality of support structures.

16. A method for fabricating a multi-piece flexural pivot as described by claim 15, wherein forming a plurality of support structures as unitary structures includes:

forming the first, second and third support structures so that said structures have near net shape geometry.

17. A method for fabricating a multi-piece flexural pivot as described by claim 16, wherein forming the first, second and third support structures so that said structures have near net shape geometry includes:

metal injection molding the support structures.

18. A method for fabricating a multi-piece flexural pivot as described by claim 15, wherein applying a braze material to a flexural material and forming a flexural assembly therefrom includes:

applying a braze material to a strip of flexural material;

stamping a plurality of flexural members from the flexural material having the braze material applied thereto; and

arranging said flexural members relative to each other for forming the flexural assembly.

19. A method for fabricating a multi-piece flexural pivot as described by claim 15, wherein:

exposing the pivot assembly to a thermal environment for brazing the flexural assembly to the plurality of support structures includes;

fixturing the pivot assembly; and

oven brazing the fixtured pivot assembly.

20. A method for fabricating a multi-piece flexural pivot as described by claim 19, wherein:

the oven brazing duration and temperature range are selected for heat treating the pivot assembly.