Method and tool for reconditioning a damaged thread

Patent metadata

Field	Value
Publication number	US-11389909-B2
Application number	US-201917055030-A
Country	US
Kind code	B2
Filing date	Oct 17, 2019
Priority date	Oct 17, 2018
Publication date	Jul 19, 2022
Grant date	Jul 19, 2022

Abstract

It is described a method for reconditioning a damaged thread (8) of a transmission (1) of a hover-capable aircraft; the damaged thread (8) being arranged inside a first hole (23a) of the transmission (1); wherein the method includes the following steps: i) centering a tool (20) on the first hole (23a); ii) inserting a first tool (25) inside the tool (20) centred on the first hole (23a) and removing the damaged thread (8) through the first tool (25); iii) inserting a second tool (26) inside the tool (20) and creating a new thread (16) inside the first hole (23a) having a diameter larger than the one of the damaged thread (8); iv) screwing an insert (61) having a thread inside the new thread (16), so that the insert (61) engages the first hole (23a) and defines a reconditioned thread (8′); and v) keeping the transmission (1) mounted on the hover-capable aircraft during steps i), ii), iii), iv).

First claim

What is claimed is:

1. A method for reconditioning a damaged thread ( 8 ) of a transmission ( 1 ) of a hover-capable aircraft; said damaged thread ( 8 ) being arranged inside a first hole ( 23 a ) of said transmission ( 1 );
said method comprising the following steps:
i) centering a tool ( 20 ) on said first hole ( 23 a );
ii) inserting a first tool ( 25 ) inside said tool ( 20 ) centred on said first hole ( 23 a ) and removing the damaged thread ( 8 ) by means of said first tool ( 25 );
iii) inserting a second tool ( 26 ) inside said tool ( 20 ) and creating a new thread ( 16 ) inside said first hole ( 23 a ) having a diameter larger than the one of said damaged thread ( 8 ); and
iv) screwing an insert ( 61 ) having a thread inside said new thread ( 16 ), so that said insert ( 61 ) engages said first hole ( 23 a ) and defines a reconditioned thread ( 8 ′); said step i) comprising the following steps:
v) inserting a pin ( 33 ) inside said tool ( 20 ) and inside said first hole ( 23 a ); and
vi) removing the pin ( 33 );
wherein said step i) comprises the steps of:
vii) screwing said pin ( 33 ) onto a further thread ( 30 ) of said tool ( 20 ); and
viii) arranging said pin ( 33 ) in abutment against an abutment surface ( 32 ) of said tool ( 20 );
said method further comprising the step of:
ix) keeping said transmission ( 1 ) mounted on the hover-capable aircraft during said steps i), ii), iii), vii).

2. The method according to claim 1 , wherein before said step i), the method comprises the following further steps:
x) removing a plurality of connecting elements ( 6 a , 6 b ) interposed between said casing ( 2 ) and said transmission ( 4 ), engaging respective said first hole ( 23 a ) and second holes ( 23 b ) of said transmission ( 1 ) and on which respective nuts ( 7 ) are screwed; said casing ( 2 ) defining said first hole ( 23 a ) and said second holes ( 23 b ); and
xi) removing said shell ( 4 ) from said casing ( 2 ) while maintaining said transmission ( 1 ) supported by said casing ( 2 ).

3. The method according to claim 2 , wherein after said steps x) and xi), the method comprises the following further steps:
xii) arranging a first bracket ( 21 ) of said tool ( 20 ) at said first hole ( 23 a ) before said step i); and
xiii) arranging a pair of additional brackets ( 22 ) of said tool ( 20 ) at respective second holes ( 23 b ) of said transmission ( 1 ) before said step i).

4. The method according to claim 3 , wherein the method further comprises the following steps:
xiv) screwing said nuts ( 7 ) onto the respective connecting elements ( 6 b ) engaging the respective said second holes ( 23 b ), during said step i).

5. The method according to claim 1 , wherein said step ii) comprises the following steps:
xv) inserting a first bush ( 40 ) inside said tool ( 24 );
xvi) arranging said first tool ( 25 ) inside a third hole ( 41 ) of said first bush ( 40 ) until a first operating end ( 70 ) of said first tool ( 25 ) is brought in correspondence with said thread to be removed ( 8 ) and inside said first hole ( 23 a ); and
xvii) actuating said first tool ( 25 ) so as to remove said damaged thread ( 8 ).

6. The method according to claim 1 , wherein said step iii) comprises the following steps:
xviii) inserting a second bush ( 50 ) inside said tool ( 20 ); and
xix) screwing said second tool ( 26 ) onto a nut screw ( 54 ) arranged inside a further fourth threaded hole ( 51 ) of said second bush ( 50 ) until a second operating end ( 71 ) of said second tool is brought ( 26 ) inside said first hole ( 23 a ).

7. The method according to claim 1 , wherein said step iii) comprises the further step xx) of screwing said insert ( 61 ) inside said new thread ( 16 ).

8. The method according to claim 1 , wherein said step ii) comprises the further step xxi) of arranging said first bush ( 40 ) against said abutment surface ( 32 ); and/or wherein said step iii) comprises the further step xxii) of arranging said second bush ( 50 ) against said abutment surface ( 32 ).

Assignees

• Leonardo Spa

Inventors

• Colombo Dario
• Regonini Roberto
• Fiorio Sergio

Classifications

• B23B49/026

  Boring bushing carriers attached to the workpiece by glue, magnets, suction devices or the like · CPC title

• B23P6/00 Primary

  Restoring or reconditioning objects (straightening or restoring form of sheet metal, metal rods, metal tubes, metal profiles, or specific articles made therefrom B21D1/00, B21D3/00; repairing defective or damaged objects by casting techniques B22D19/10) · CPC title

• B23B49/023

  Bushings and their connection to the template · CPC title

• B64C27/12

  Rotor drives · CPC title

• B64F5/40

  Maintaining or repairing aircraft · CPC title