Break away fastening system

#The present invention relates to a fastening system for fastening a member to a structural metal part and, more particularly, for fastening a member to sheet metal. A threaded metal stud having an annular welding surface is fastened to the structural part in short-time arc welding, and a fracturable lock nut is screwed onto the stud to fasten the member to the structural part.

#Metallic weld studs are typically solid, non-compressible bodies which are formed by standard fastener stamping methods such as being cold headed from rod materials. Such weld studs are welded to a component surface by using a known welding device which provides energy through the weld stud to melt both a circular sacrificial weldment element, as well as a portion of the component base material. The weld stud is fixed to the base material due to the commingling and cooling of the liquefied metals. The welding device, in particular a weld gun, grasps the weld stud using clamping jaws in a region between a shoulder of the stud and the end of the face to be welded. Each weld stud is placed into the mouth of weld gun one at a time immediately prior to welding. The size, weight, and configuration of these studs prevent their use in blow fed weld guns.

#Increased fuel economy demands within transportation industries have led to the use of thinner and thinner gauge materials. In particular, metallic composite materials and particularly aluminum composite materials with a polymer core have effectively been used as surface or skin materials for various structures. These very thin metallic laminates are typically coupled or fastened to a support structure by being fastened to the support structure on one side of the laminate. To this end, it is known to fasten an ordinary weld stud to the laminate structure to facilitate the coupling of the stud to the structure.

#The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

#FIG. 1 is a side view of the drawn arc weld stud according to the teachings of the present invention;

#FIG. 2 is a bottom view of the drawn arc weld stud according to FIG. 1;

#The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

#FIG. 1 represents the drawn arc weld stud 10 according to the teachings of the present invention. The weld stud 10 is formed of three major components; a shank 12, a head 14, and an annular weldment portion 16. By way of non-limiting example, the shank 12 can be a M6 threaded fastener. Equally, the shank can take the form of pine-tree connector or other sized threaded fastener.

#The head 14 portion is formed using cold heading methodologies. The head 14 for a M6 fastener has an exterior diameter of about 13 mm and a thickness of about 2 mm. The head further has a flat lower surface 15 having a diameter of about 13 mm. The strength of the fastener is a function of the thickness of the head. As such, as the thickness of the head is increased, generally the strength of the weld stud 10 is increased. Increasing the strength of the fastener often leads to an undesirable failure of the interface of the fastener and the laminate material. Such failures lead to the fastener being pulled out of the laminate material, leaving a hole in the thin sheet metal.