Deformed blind rivet loop clamp

A suspension loop clamp consisting of a blind rivet nut, a metal strip, and a fastener. The blind rivet nut is inserted into the flat strip through a circular hole in the strip. The blind rivet is then plastically deformed by compression axially applied to both ends of the blind rivet nut from an unset condition to a set condition forming a radially outwardly protruding bulge, which serves to bind the blind rivet nut element to the strip. The blind rivet nut bulge and the loop clamp it is attached to are then additionally dented and thus deformed in a radial pattern so as to be zigzag in shape when viewed through a cross section. This stiffens the protruding bulge so as to restrict the blind rivet nut from reverting back to its original shape when a tensile load is applied opposite to the flange of the rivet nut. The strip of sheet metal is then formed longitudinally into a loop clamp which has bends with holes, at each end, through which a fastener is inserted to clamp the loop around a conduit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation in Part of application Ser. No. 16/792,257 filed 16 Feb. 2020 and now abandoned.

DESCRIPTION OF THE PRIOR ART

Ring hangers for tubular sections as shown inFIG.1have long been made in various styles from castings or forgings. The blind rivet nutFIG.6referred to here is identical to the unit patented by Waner U.S. Pat. No. 2,149,199 in 1939. Later in 1993 MacGregor U.S. Pat. No. 5,213,378 added an extension to the flanged end of the rivet nut to use as a gas or fluid passageway. In 2004 Morishima of Japan JP-20044160486-A filed an application for a modified nose piece for a typical blind rivet applicator tool. Morishima showed in his drawings a nosepiece applied on a pipe. The inside of the pipe slightly distorts the bulge of the rivet nut. The distortion follows the interior of the pipe so it is minor and not distinct enough to add any structure to the bulged portion. Morishima claims none. Morishima had no intention to do so as the blind rivet nut was being applied in its usual application to be stressed pulling out of the pipe and his design was to shape the flange to the outer surface of the curved pipe.

None of the references presented here use the blind rivet nut in reverse direction nor do any of them indent the bulge to form a zigzag as a secondary operation to structurally stiffen the bulge portion to make it suitable to be used in reverse of its original intent. None of the prior art presented combines the blind rivet nut with a loop clamp for use as a suspension hanger.

FIELD OF THE INVENTION

The loop hanger presented here is for use in building construction for both electrical and plumbing applications to support various conduits typically from threaded rods.

SUMMARY OF THE INVENTION

This loop hanger is of the single support rod type which firmly and securely supports a conduit and makes use of blind rivet nuts to act as the threaded member of the hanger. The blind rivet nut is attached to a loop clamp also known as a round clamp. The embodiment presented here is a new and novel way to secure a blind rivet nut to a loop clamp. Mounting a blind rivet nut in reverse of its originally intended configuration leads to failure of the connection under tensile loading. This design presents a new method of firmly attaching the blind rivet nut to prevent its failure under tensile loading conditions. It is accomplished by recompressing the initial bulge formed when the blind rivet nut is first attached. During this second compression the bulge is deformed into a zigzag pattern as viewed radially. This deformation greatly enhances the stiffness of the bulge. In the eighty years since the blind rivet nut has been invented there are no records of it being used in reverse by stiffening its bulge with a secondary operation. Blind rivet nuts are used where access to the back side of the rivet is impossible, hence its name “blind rivet nut”. The use of the blind rivet nut enables a ring hanger design without the need for a welded the assembly. It also allows for a lighter structure in the hanger while still meeting the standard load requirements.

DETAILED DESCRIPTION OF THE INVENTION

This invention uses a blind rivet nut as shown inFIG.6as the threaded element of a suspension loop clamp used to support a conduit. This loop clamp consists of a blind rivet nut, a perforated strip of flat metal, and a fastener.

The loop clamp is fabricated by cutting a flat strip of metal, seeFIG.3, to the appropriate length and then piercing a hole21through each end with an appropriate punching tool sized suitably for the fastener and thereafter punching a third hole22between the other two holes. This third hole being large enough to received the blind rivet nut. As is shown inFIG.4, the strip may also have a slot30in it to enable it to be more easily bent. As shown inFIG.5the strip then has its end sections39bent up mostly perpendicular. As shown inFIG.7The blind rivet nut24is then inserted into the larger hole from the opposite side of the strip to the bent up ends. As shown inFIG.8the blind rivet nut is then compressed using a punch press or another suitable compression equipment, between two cylindrical pins aligned axially to form a bulge, or bead26in the blind rivet nut. The bulge appears on the outside of the loop, and binds the blind rivet nut to the strip23. The bulge, thus formed, could be pulled out back to its original shape under certain tensile loads. This assembly requires the blind rivet nut to be further deformed into a zigzag shaped bulge28shown inFIG.9by a second compression tool. This second cylindrical compression tool is larger in its inside diameter than the body of the blind rivet nut containing the thread.

FIG.11shows the arrangement of the tooling required for the first deformation. The first cylindrical compression tool31is forced towards the supported cylindrical anvil32compressing the blind rivet nut25. The compression is accomplished in a standard mechanical press or a hydraulic press. This forces a circular bulge26to form in the blind rivet nut, fixing the blind rivet nut to the bent strip23.FIG.12shows the same parts in section showing the bulge26formed on the strip23.

The second cylindrical form tool, seeFIG.10, indents the bulge radially into a zigzag shape using wedge shaped edges38. No pressure is applied to the central part of the rivet nut as its threads would distort under any further compression.

The second compression tool arrangement, as shown inFIG.13, form the zigzag into the bulged part of the blind rivet nut. The zigzag tool33applies a force to the blind rivet nut bulge impressing a zigzag pattern radially on to the bulge, steel strip and the flange of the blind rivet nut. The compression is accomplished into the anvil32, again using a standard mechanical press or a hydraulic press.FIG.14is a sectional view of the tool showing the bulge of the blind rivet nut27and the resulting zigzag deformation of the bulge28.

The strip is then formed longitudinally into a mostly cylindrical shape shown inFIG.15except a flattened area40where the blind rivet nut has been inserted.FIG.15further shows the blind rivet nut27with its deformed bulge28on the formed loop29.

InFIG.16a sheet metal screw fastener36is shown placed into the end holes of the loop to secure them together forming a loop clamp. A fastener as described here may refer to a nut and machine screw fastener35as shown inFIG.2, a sheet metal screw36as shown inFIG.16, or any other suitable fastener. Another embodiment of the loop clamp has a slot30in the strip to reduce the bending force required to wrap or unwrap the strip around a conduit and is shown inFIG.4. To use the deformed blind rivet loop clamp, a threaded rod34, shown inFIG.2, is attached to a structure and is threaded into the deformed blind rivet nut27. The machine screw fastener35of the loop29is then tightened around a conduit37.

ITEMS IN THE DRAWINGS

21. Small apertures in flat strip for fastener.22. Additional larger aperture in flat strip for blind rivet nut.23. Flat strip with ends bent up24. Rivet nut25. Rivet nut bulged26. Bulge in the rivet nut27. Rivet nut zigzag deformed28. Zigzag shape in rivet nut29. Loop as formed.30. The slot in the strip.31. First compression top tool32. Fixed anvil of compression tool33. Zigzag shaped compression tool used in second compression34. Threaded rod attachment35. Bolt and nut as fastener36. Sheet metal screw as fastener37. Pipe or conduit.38. Wedge shaped edges in tool used to form zigzag.39. Ends bent up for fasteners.40. Flattened section of loop

CONCLUSION, RAMIFICATIONS, AND SCOPE

The embodiment presented here enables a common blind rivet nut to be used as the threaded component in a suspension loop clamp. This is a new and novel use. This product replaces iron castings which often create air pollution during their manufacture. The loop clamp presented here enables pre-plated, or paint coated stock to be used for the loop clamp as no welding is required for the assembly. The blind rivet nuts are a standard commercial plated product and as such available at low cost. By not having to do secondary post processes to the assembled product, the item may be packaged directly off an automated manufacturing assembly line eliminating the added costs of handling and transport.