Vibration welding structure for fixing instrument panel attachment

A vibration welding structure for fixing an instrument panel attachment wherein the attachment is vibration-welded to an instrument panel by first positioning said attachment on and along the instrument panel and then vibrating either one of the instrument panel and the attachment,

• wherein a projection having a generally trapezoidal shape progressively decreasing in width from a proximal end thereof to a distal end thereof and being resiliently deformable in a predetermined vibrating direction is provided on one of the instrument panel and the attachment so as to project toward other of the instrument panel and the attachment,
• wherein a fitting portion is provided in the other of the instrument panel and the attachment for fitting engagement with a distal end portion of said projection, said fitting portion comprises a groove for receiving therein the distal end portion of the projection,
• wherein said one of the instrument panel and the attachment has a reinforcing rib projecting toward and vibration-welded to the other of the instrument panel and the attachment, said reinforcing rib having a recessed portion facing the groove of the fitting portion, and
• wherein said projection is disposed on a bottom of the recessed portion and projecting therefrom toward the groove of the fitting portion so that the distal end portion of said projection is received in said groove of the fitting portion.