US 12,233,518 B2
Method for the servo-installation of a threaded fastener
Benoit Regnard, Les Clayes sous Bois (FR); and Clément Rousseau, Paris (FR)
Assigned to LISI AEROSPACE, Paris (FR)
Filed by LISI AEROSPACE, Paris (FR)
Filed on May 2, 2024, as Appl. No. 18/653,201.
Claims priority of application No. 2305258 (FR), filed on May 26, 2023.
Prior Publication US 2024/0391069 A1, Nov. 28, 2024
Int. Cl. B25B 23/147 (2006.01)
CPC B25B 23/147 (2013.01) 12 Claims
OG exemplary drawing
 
1. A method of installing a threaded fastener into a hole in a structure, the threaded fastener including a screw, having an end, a length (L0) and a head having a length (Lt), and a nut having a length (Le), the method comprising the following steps:
a) inserting the screw into the hole, placing the nut at an initial position on the end of the screw, and screwing the nut onto the screw,
b) simultaneously transmitting ultrasonic waves into the fastener and receiving reflected ultrasonic waves for the measurement of a first parameter representative of a variation in said waves, said first parameter providing an indirect measure of an axial tension in the screw,
c) stopping the screwing when a target value for the first parameter is reached, characterized in that the process further comprises the following steps:
d) determining the thickness of the structure to be tightened (L1) by calculating the thickness (L1) with a calculator during the screwing of the nut onto the screw, and
e) determining the target value of the first parameter in accordance with the thickness of the structure to be tightened (L1) and geometrical characteristics of the fastener (10).