Patent FR-2939341-A1 (FR)
Title: Friction welding of two pieces of wood, comprises supplying assembly of two parts mutually along two adjacent surfaces to contact with each other, and cutting the swivel at point to provide a conical shape rotating around an axis
Inventor: BOCQUET JEAN FRANCOIS
IPC: B23K20/12
Filed: 2008-12-09
Abstract: The process comprises supplying the assembly of two parts (1, 2) mutually along two adjacent surfaces to contact with each other using a common linking swivel, which contacts with continuous drilling extent through the two parts, and cutting the swivel at point to provide a conical shape rotating around an axis and to conform the drilling extent so that the drilling extent has an external profile, which matches the swivel. The diameter of the swivel varies according to a diameter decreasing from one end to the other end so that the swivel is axially engaged in drilling. The process comprises supplying the assembly of two parts mutually along two adjacent surfaces to contact with each other using a common linking swivel, which contacts with continuous drilling extent through the two parts, and cutting the swivel at point to provide a conical shape rotating around an axis and to conform the drilling extent so that the drilling extent has an external profile, which matches the swivel. The diameter of the swivel varies according to a diameter decreasing from one end to the other end so that the swivel is axially engaged in drilling without relative rotation. The welding of two parts is obtained by the rapid rotation of the swivel into the drilling together with an effort of compression along the direction of the axis. The decreasing diameter of the drilling extent of the swivel is linear such that the drilling provides a profile of regular cone form. The internal profile of the drilling extent is obtained using a rotating drilling tool for perforating two wood pieces and of which the outer surface is partly identical to that of the swivel that axially engages in the hole. The part of the swivel external to the drilling extent is shaped to have a rotation extension of any shape for cooperating with a tool for rapidly rotating the swivel around the drilling axis. The depth of the drilling extent formed continuously in two parts is greater than that of the swivel, where the outer surface of the swivel is contacted with the hole. The drilling extent formed in two pieces of wood traverses the first, extends into the second, and forms a blind hole in the second part. The linking of the swivel and two parts, to the right of a common hole, is carried out by rapid rotation of the swivel around its rotational axis. The effort of axial compression on the swivel is constantly maintained in its outer surface with the wall opposite to the hole to cause a slight shifting of the swivel into the hole during the welding cycle. The surface with regards to the drilling extent and/or conical swivel engaged in the hole are densified for increasing the quantity of material present in the welding area by compression of wood fibers in the two parts. The densification of the wood is carried out by drilling tool controlled by rotation to form the drilling extent, rotated in the direction opposite to the drilling direction. An independent claim is included for a welded assembly of two wood pieces.