Patent FR-2984193-A1 (FR)
Title: Device, useful for welding nut onto sheet, comprises welding body delimiting housing emerging axially in lower face, and detection unit for detecting escape of air and forming keying unit to avoid welding of element in incorrect position
Inventor: BRICE STEPHANE
IPC: B23K11/00
Filed: 2011-12-19
Abstract: The device comprises a upper welding body (26a) that is delimited by a lower face (32) and delimits a housing (30) emerging axially in the lower face, where a welding element (12) is delimited by a peripheral face (16), an upper face and a lower face, and occupies a correct welding position in which welding feet are arranged in bottom and rest against an upper face of a sheet and an incorrect position in which the welding feet are arranged on a top, and a detection unit for detecting an escape of air and forming a keying unit to avoid the welding of the element in the incorrect position. The device comprises a upper welding body (26a) that is delimited by a lower face (32) and delimits a housing (30) emerging axially in the lower face, where the body is axially movable between a high steady position and a low welding position in which the lower face of the body is designed to cooperate with a upper face of an welding element (12), and the welding element is delimited by a peripheral face (16), the upper face and the lower face, and occupies a correct welding position in which the welding feet are arranged in bottom and rest against an upper face of a sheet and an incorrect position in which the welding feet are arranged on a top, and a detection unit for detecting an escape of air and forming a keying unit to avoid the welding of the element in the incorrect position. The housing of the body is connected to an air source compressed to send air towards the welding element. The lower face of the body is present in an axial support on welding feet when the welding element occupies the incorrect position so that the lower face of the body and a lower face of the welding element define a slot through which the air leaks. The device further comprises: an air conduit that extends from the air source to the housing of the body; a centering pin that is axially movable between a low steady position in which the centering pin is retracted with a lower part of the sheet, and a high centering position in which the centering pin cooperates with the welding element to center the centering pin onto the sheet; and a lower welding body that comprises a upper face for supporting the sheet and is designed to cooperate with the higher body to run an electric current through the welding element and to weld the welding feet of the welding element onto the associated sheet. The detection unit is connected to the air conduit to detect a possible escape of air, and cooperates with a control unit to announce the escape and to stop the device. The detection unit is a pressure controller designed to detect a decrease in pressure of the air conduit. The welding element is hexagonally delimiting a tapped hole. The sheet delimits the hole. The centering pin comprises a truncated portion that is conceived to cooperate with a truncated seat delimited by the welding element. The lower body delimits an axial passage hole of the centering pin. The welding element comprises three welding feet that extend from the lower face of the welding element and are systematically arranged on a peripheral edge of the lower face of the welding element. The upper face of the welding element and the lower face of the upper body are designed to be in the axial support one against the other.