Method and system for applying a compressive preload

Patent metadata

Field	Value
Publication number	US-10048144-B2
Application number	US-201313940321-A
Country	US
Kind code	B2
Filing date	Jul 12, 2013
Priority date	Jul 12, 2013
Publication date	Aug 14, 2018
Grant date	Aug 14, 2018

Abstract

A method of validating a compressive axial preload on adjacent rotatable elements serially arranged around a shaft, created through application of a progressively increasing axial tension to a tensioning member configured to compress the elements when the axial tension is applied. The method includes monitoring a load in the tensioning member and/or in one or more of the elements, and an elongation of the tensioning member, during application of the axial tension, determining at least one validation parameter from the load and the elongation, comparing each validation parameter with a respective predetermined range therefor; and if at least one of the at least one validation parameter is out of the respective predetermined range, correcting the preload on the elements, and repeating the method. A method of applying the compressive preload and a system for validating the compressive preload are also described.

First claim

The invention claimed is:

1. A method of validating a compressive axial preload on adjacent rotatable elements serially arranged around a shaft, the axial preload being created through application of a progressively increasing axial tension to a tensioning member configured to compress the elements when the axial tension is applied thereto, the tensioning member corresponding to the shaft around which the elements are arranged or to another elongated member, the method comprising:
a) monitoring a load in the tensioning member and/or in one or more of the elements during application of the axial tension;
b) monitoring an elongation of the tensioning member during application of the axial tension;
c) determining at least one validation parameter from the load and the elongation;
d) comparing each validation parameter with a respective predetermined range; and
e) if at least one of the at least one validation parameter is out of the respective predetermined range, correcting the preload on the elements, and repeating the method from step a).

2. The method as defined in claim 1 , wherein the preload is maintained through engagement of a retaining member with the tensioning member to prevent retraction of the tensioning member once the axial tension thereon is released, and wherein:
steps c) and d) are performed before the retaining member is engaged with the tensioning member;
if each validation parameter is within the respective predetermined range, the axial tension is applied up to a predetermined value, the retaining member is engaged with the tensioning member, and the axial tension is released; and
if at least one of the at least one validation parameter is out of the respective predetermined range, step e) includes releasing the axial tension on the tensioning member before the retaining member is applied, at least partially disassembling elements from around the shaft, re-assembling the elements around the shaft, and re-applying the axial tension on the tensioning member.

3. The method as defined in claim 2 , wherein the load increases linearly as a function of the elongation following a first rate of increase up to a point of transition and following a second rate of increase after the point of transition, and steps c) and d) include:
determining the first rate of increase of the load with respect to the elongation; and comparing the first rate of increase with the respective predetermined range; and/or
determining a transition load at the point of transition and comparing the transition load with the respective predetermined range; and/or
determining the second rate of increase of the load with respect to the elongation and comparing the second rate of increase with the respective predetermined range.

4. The method as defined in claim 3 , wherein step c) includes determining the first rate of increase of the load with respect to the elongation, and wherein the respective range for the first rate of increase is determined around a respective nominal value determined based on a stiffness of the elements and of the tensioning member.

5. The method as defined in claim 3 , wherein step c) includes determining the transition load, and wherein the respective range for the nominal value for the transition load is determined around a respective nominal value determined based on a required interference fit between the elements and the shaft.

6. The method as defined in claim 3 , wherein step c) includes determining the second rate of increase of the load with respect to the elongation, and wherein the respective range for the second rate of increase is determined around a respective nominal value determined based on a stiffness of the tensioning member without the elements.

7. The method as defined in claim 3 , wherein step c) includes determining the first rate of increase of the load, the transition load and the second rate of increase of the load.

8. The method as defined in claim 1 , wherein the preload is maintained in the assembly through engagement of a retaining member with the tensioning member preventing retraction of the tensioning member once the axial tension thereon is released, and wherein:
steps c) and d) are performed after the retaining member is engaged with the tensioning member and the axial tension is released;
if at least one of the at least one validation parameter is out of the respective predetermined range, step e) includes re-applying the axial tension on the tensioning member, adjusting a position of the retaining member on the tensioning member, and releasing the axial tension.

9. The method as defined in claim 8 , wherein the load increases linearly as a function of the elongation following a first rate of increase up to a point of transition and following a second rate of increase after the point of transition, and steps c) and d) include:
determining residual load at a point after the axial tension is released and comparing the residual load with the respective predetermined range; and/or
determining an effective load corresponding to a difference between the residual load and the load at the point of transition and comparing the effective load with the respective predetermined range; and/or
determining an effective load energy between the point after the axial tension is released and the point of transition and comparing the effective load energy with the respective predetermined range.

10. A method of applying a compressive axial preload on adjacent rotatable elements serially arranged around a shaft, the method comprising:
a) inducing the compressive axial preload by applying axial tension to a tensioning member connected to an abutment surface pressing against the elements when the tensioning member is under the axial tension, the tensioning member corresponding to the shaft around which the elements are arranged or to another elongated member, the axial tension being applied in a progressively increasing manner;
b) monitoring a load in the tensioning member and/or in one or more of the elements and an elongation of the tensioning member as the axial tension is applied;
c) determining at least one validation parameter from the load and the elongation;
d) comparing each validation parameter with a respective predetermined range therefor;
e) if each validation parameter is within the respective predetermined range, applying the axial tension up to a predetermined value, engaging a retaining member with the tensioning member to block retraction of the tensioning member and maintain the compressive axial preload on the elements, and releasing the axial tension; and
f) if at least one of the at least one validation parameter is out of the respective predetermined range, releasing the axial tension on the tensioning member before the retaining member is engaged, at least partially disassembling elements from around the shaft, re-assembling the elements around the shaft, and repeating the method from step a).

11. The method as defined in claim 10 , wherein the load increases linearly as a function of the elongation following a first rate of increase up to a point of transition and following a second rate of increase after the point of transition, and steps c) and d) include:
determining the first rate of increase of the load with respect to the elongation; and comparing the first rate of increase with the respective predetermined range; and/or
determining a transition load at the point of transition and comparing the transition load with the respective predetermined range; and/or
determining the second rate of increase of the load with respect to the elongation and comparing the second rate of increase with the respective predetermined range.

Assignees

• Pratt & Whitney Canada

Inventors

• Remy Patrice
• Gaudet Pierre

Classifications

• G01L5/133 Primary

  for measuring thrust of propulsive devices, e.g. of propellers (aeroplanes B64C; marine propulsion B63H; jet-engines F02K) · CPC title

• G01M15/14

  Testing gas-turbine engines or jet-propulsion engines · CPC title

• G01M15/00

  Testing of engines · CPC title

• B25B23/14

  Arrangement of torque limiters or torque indicators in wrenches or screwdrivers (couplings for transmitting rotation or clutches F16D; devices for measuring torque per se G01L) · CPC title

• B23P19/067

  Bolt tensioners (for hand tools B25B29/02) · CPC title