Bore serration for locking threaded inserts against rotation

• US 7,704,028 B2
• Filed: 05/08/2008
• Issued: 04/27/2010
• Est. Priority Date: 05/08/2007
• Status: Expired due to Fees

• Current Assignee: Rolls-Royce Deutschland Limited & Company KG (Rolls-Royce Holdings Plc)
• Original Assignee: Rolls-Royce Deutschland Limited & Company KG (Rolls-Royce Holdings Plc)
• Inventors: Mielke, Rainer
• Primary Examiner(s): ESTREMSKY, GARY WAYNE
• Application Number:
  US12/149,840
• Publication Number:
  US 20080279652A1
• Time in Patent Office: 719 Days
• Field of Search: 411/180, 411/402, 411/111, 411/116, 411/144, 411/163, 411/177, 411/181, 411/188, 811/211, 811/244, 811/25
• US Class Current: 411/180
• CPC Class Codes: F16B 33/002 Means for preventing rotation of screw-threaded elements F16B39/00 takes precedence
• CPC Class Codes: F16B 37/122 Threaded inserts, e.g. "rampa bolts"
• CPC Class Codes: F16D 1/101 without axial retaining means rotating with the coupling
• CPC Class Codes: F16D 2001/103 the torque is transmitted via splined connections

Abstract

A bore serration for locking externally serrated inserts (3) against rotation, with the external serration (4) comprising several teeth (5), and particularly for use with components made of hard, brittle materials, includes an arcuate serration (10) featuring arcuate recesses (7) produced by plunge or circumferential surface milling. Each of the recesses positively accommodates at least two teeth (5) of the outer serration (4) of the threaded insert (3). The arcuate serration can be produced with high dimensional accuracy without damaging the workpiece and with reduced wear of the tool, and ensures a long service-life of the threaded insert.

Claims

1. A system for attaching a threaded fastener to a component comprising:

a threaded insert having an external serration including a plurality of externally projecting teeth distributed around a circumference of the threaded insert, the threaded insert also having a threaded portion,

a component having a bore for receiving the threaded insert, the bore having an arcuate serration including at least one inwardly facing arcuate recess positioned on an internal circumference of the bore, the at least one arcuate recess having at least one of a different size and shape as compared to the teeth of the threaded insert and being positioned and sized to receive and engage at least two teeth of the external serration of the threaded insert to lock the threaded insert against rotation with respect to the component when the threaded insert is positioned in the bore and to allow a threaded fastener to be engaged with the threaded portion of the threaded insert to attach the threaded fastener to the component.

2. The system of claim 1, wherein the arcuate serration includes a plurality of inwardly facing arcuate recesses positioned around the internal circumference of the bore, with a plurality of the arcuate recesses each positioned and sized to receive and engage at least two teeth of the external serration of the threaded insert to lock the threaded insert against rotation with respect to the component, when the threaded insert is positioned in the bore.

3. The system of claim 2, wherein at least one arcuate recess is of a different size than other arcuate recesses to receive a remainder quantity of the teeth if a number of teeth of the external serration is not an integer multiple of a number of arcuate recesses.

4. The system in of claim 3, wherein an arcuate surface of each arcuate recess engages at least a portion of outer flanks of the teeth positioned within the respective arcuate recess.

5. The system of claim 4, wherein the arcuate recesses each include a radiused arcuate internal edge.

6. The system of claim 5, wherein the arcuate recesses extend only partially through the component to limit an axial movement of the threaded insert through the component.

7. The system of claim 1, wherein at least one arcuate recess is of a different size than other arcuate recess to receive a remainder quantity of the teeth if a number of teeth of the external serration is not an integer multiple of a number of arcuate recesses.

8. The system in of claim 7, wherein an arcuate surface of the arcuate recesses engages at least a portion of outer flanks of the teeth positioned within the respective arcuate recess.

9. The system of claim 8, wherein the arcuate recesses each include a radiused arcuate internal edge.

10. The system in of claim 1, wherein an arcuate surface of the arcuate recesses engages at least a portion of outer flanks of the teeth positioned within the respective arcuate recess.

11. The system of claim 1, wherein the arcuate recesses each include a radiused arcuate internal edge.

12. A method for locking a threaded insert against rotation, comprising:

providing a threaded insert with an external serration having a plurality of teeth,

forming an arcuate serration in a bore of a component, the arcuate serration having a plurality of arcuate recesses produced by at least one of plunge and circumferential surface milling, such that each of the arcuate recesses is constructed and arranged to receive at least two teeth of the external serration of the threaded insert to lock the threaded insert against rotation with respect to the component when positioned in the bore.

13. The method of claim 12, wherein each accurate recess is constructed and arranged to receive up to four teeth of the external serration.

14. The method of claim 13, wherein at least one arcuate recess is formed of a different size than other arcuate recesses to receive a remainder quantity of the teeth if a number of teeth of the external serration is not an integer multiple of a number of arcuate recesses.

15. The method of claim 14, wherein an arcuate surface of each arcuate recess is constructed and arranged to engage at least a portion of outer flanks of the teeth positioned within the respective arcuate recess.

16. The method of claim 15, wherein the arcuate recesses are each formed to include a radiused arcuate internal edge.

17. The method of claim 16, wherein the arcuate recesses are formed to extend only partially through the component to limit an axial movement of the threaded insert through the component.

18. The method of claim 12, wherein at least one arcuate recess is formed of a different size than other arcuate recesses to receive a remainder quantity of the teeth if a number of teeth of the external serration is not an integer multiple of a number of arcuate recesses.

19. The method of claim 18, wherein an arcuate surface of each arcuate recess is constructed and arranged to engage at least a portion of outer flanks of the teeth positioned within the respective arcuate recess.

20. The method of claim 19, wherein the arcuate recesses are each formed to include a radiused arcuate internal edge.

21. The method of claim 12, wherein an arcuate surface of each arcuate recess is constructed and arranged to engage at least a portion of outer flanks of the teeth positioned within the respective arcuate recess.

22. The method of claim 12, wherein the arcuate recesses are each formed to include a radiused arcuate internal edge.