Self-drilling expansion fastener and method of forming same

Abstract

A self-drilling expansion fastener is integrally formed of a sheet metal material for locking two or more sheet workpieces together, and includes an expansion structure and a drill structure. The expansion structure has a plurality of internal threads and force-distributing bars. The drill structure has a chip guard for covering a head of the expansion structure, and a drill forward projected from the chip guar for self-drilling a hole. When an externally threaded element is screwed into the expansion structure to mesh with the internal threads, the force-distributing bars are brought to expand outward and are finally compressed into a folded state to thereby tightly lock the sheet workpieces to one another. A method of forming the self-drilling expansion fastener is also disclosed.

Description

RELATED APPLICATIONS[0001]This application is a Divisional patent application of co-pending application Ser. No. 14 / 083,641, filed on 19 Nov. 2013, now pending. The entire disclosure of the prior application, Ser. No. 14 / 083,641 is considered a part of the disclosure of the accompanying Divisional application and is hereby incorporated by reference.FIELD OF THE INVENTION[0002]The present invention relates to an expansion fastener integrally formed of a sheet metal material, and more particularly to an expansion fastener capable of self-drilling a hole.BACKGROUND OF THE INVENTION[0003]An expansion fastening device is usually used to fixedly connect multiple sheet workpieces, such as building panels, to one another, and includes a bolt and an expansion fastener. FIG. 1 shows a typical conventional expansion fastener 10, which includes a barrel body 11 having a plurality of longitudinally extended elongated slots 12 formed thereon to define a plurality of laterally spaced middle bars 1...

AI Technical Summary

Benefits of technology

[0005]A primary object of the present invention is to provide a self-drilling expansion fastener, with which a user can lock two or more sheet workpieces together with only one installation step to largely simplify the working procedure and upgrade the working efficiency.

[0006]Another object of the present invention is to provide a method of integrally forming a self-drilling expansion fastener from a sheet metal material through a series of punching and stamping procedures, so that the self-drilling expansion fastener can be easily manufactured with upgraded production efficiency.

[0007]To achieve the above and other objects, the self-drilling expansion fastener according to the present invention is integrally formed of a sheet metal material for locking two or more sheet workpieces together, and includes an expansion structure and a drill structure located at a head of the expansion structure. The expansion structure has a plurality of internal threads and a plurality of force-distributing bars. The drill structure has a chip guard for covering the head of the expansion structure, and a drill forward projected from the chip guard for self-drilling a hole on the sheet workpieces, so that the expansion structure can be extended through the sheet workpieces and tightly received in the drilled hole with the force-distributing bars fully located behind the sheet workpieces. When an externally threaded element is gradually screwed deeper into the expansion structure to mesh with the internal threads, the force-distributing bars are brought to expand outward and are finally compressed into a folded state to thereby tightly lock the sheet workpieces to one another.

Problems solved by technology

The conventional expansion fastener 10 is disadvantageous in terms of assembling and installation thereof.

First, the out 14 and the bottom cover 15 are connected to the barrel body 11 by welding, which is time and labor consuming to result in high manufacturing cost of the expansion fastener 10.

The above installation is apparently troublesome and consumes a lot of time and labor.

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