Abstract:
Fastening apparatus and method for forming a rivet-type fastener are disclosed for joining two pieces together that is particularly suitable for use in constructing a building. The fastening apparatus utilizes an actuating rod preferably driven by a hydraulic cylinder with the rod being inserted through a fastening section and holes in pieces to be fastened. A set of dies has one fixed and one pulled by the rod through the holes to form at least one rolled flange or two rolled flanges to form a hollow fastener that secures the pieces together. The rod is automatically returned to an extended position to be ready for the next operation. The fastener has a relatively large inside diameter in relation to the thicknesses of the pieces being fastened to avoid shear of the piece and prevent having the flange deform under load.

Description:
TECHNICAL FIELD 
     The present invention relates to a novel and improved fastening apparatus and method and rivet-type fastener for joining together at least two pieces. 
     BACKGROUND ART 
     The fastening together of pieces such as two pieces of sheet metal used in a building has heretofore been accomplished primarily by the drilling of holes and use of the conventional bolt and nut fasteners. In a building the pieces may be, for example, wall panels, roof panels, frame panels or gussets connected at joints to frame panels between roof and side walls and also to roof trusses. A building using the rivet-type fasteners disclosed herein is described in a copending application entitled STRAIGHT WALL BUILDING AND METHOD AND APPARATUS FOR CONSTRUCTING. 
     Tuttle U.S. Pat. No. 1,176,793 and Klenk U.S. Pat. No. 3,261,073 disclose a clinching punch hand tool which has a die that perforates layers of sheet metal and clinches the layers together to form a rivet-type fastener. 
     Ashby U.S. Pat. No. 4,306,511 discloses a power-driven pierce and extrusion punch and pierce curl die that pierces a hole through two pieces and curls the punched portions back to effect a fastening (FIG. 1A). 
     La Barge U.S. Pat. Nos. 4,611,381 and 4,688,316 teach making hollow rivets in two pieces of malleable material using a punch die and forming interlocking flanges from the punched out portions of the two sheets. 
     Ueno U.S. Pat. No. 4,843,204 discloses an open-ended protruding piece in a first plate inserted into a hole in a second plate with a flange formed in the protruding edge to form a rivet-type fastener. 
     DISCLOSURE OF THE INVENTION 
     The fastening apparatus and method disclosed includes a reciprocally movable actuating rod preferably driven by a hydraulic cylinder that is normally extended and has a free end portion that is inserted through aligned holes in at least two pieces to be fastened together. The pieces in a sheet metal building are the skin and frame panels, gussets and roof truss panels. A hollow fastening section is disposed in and extends beyond the holes. The actuating rod extends through a first die and carries a second die so that as the second die is drawn back through the holes the dies cause a radial enlargement of at least one end of the fastening section to form an end flange larger than the holes to form a hollow rivet-type fastener that fastens the two pieces together. In one embodiment disclosed the fastening section has one end formed as a part of one of the pieces being fastened and in another embodiment the fastening section is separate from the pieces being fastened and preferably has a flange at one end with the other end sized to insert into the holes in the pieces and a second flange is formed in the inserted end by the fastening apparatus after insertion into the holes. 
     The rivet-type fastener so formed has a relatively large inside diameter in comparison to the thickness of the pieces being fastened to afford substantial surface area contact by the flange against the piece the flange contacts and the thickness of the fastener is at least substantially equal to the thickness of the thickest of the two pieces being fastened to avoid shear of the pieces and prevent having the flange deform under load. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Details of this invention are described in connection with the accompanying drawings in which like parts bear similar reference numerals and in which: 
     FIG. 1 is a perspective view of fastening apparatus embodying features of the present invention. 
     FIG. 2 is an exploded view of portions of the fastening apparatus shown in FIG. 1. 
     FIG. 3 is an enlarged perspective view of the free end portion of the actuating rod. 
     FIG. 4 is an exploded view of the detachable die holder. 
     FIG. 5 is a sectional view taken along line 5--5 of FIG. 1 with the movable die in an almost fully retracted position. 
     FIG. 6 is a sectional view taken along line 6--6 of FIG. 2 showing a hollow fastening section with a flange at one end. 
     FIG. 7 is a sectional view showing a partially retracted movable die in relation to the fastening section and sheets being fastened. 
     FIG. 8 is a sectional view showing the movable die moved to a further retracted position. 
     FIG. 9 is a sectional view taken along line 9--9 of FIG. 5. 
     FIG. 10 is an enlarged sectional view of the movable die. 
     FIG. 11 is a front elevational view of the completed rivet-type fastener drawn to full scale. 
     FIG. 12 is a sectional view taken along line 12--12 of FIG. 11. 
     FIG. 13 is a sectional view of another form of fastening section and fastening apparatus used to fasten the pieces together with the shown movable die in an extended position. 
     FIG. 14 is a sectional view showing the fastened pieces accomplished by the fastening apparatus of FIG. 13. 
    
    
     DETAILED DESCRIPTION 
     Referring now to FIG. 1 there is shown a portable hydraulic pressure source 12 that connects into an electric socket with source 12 having a fluid line 13 for supplying a fluid under pressure. The fastening apparatus 14 shown includes a two-way hydraulic cylinder 15 having a two-piece outer housing 17 with a rear housing portion 17a with external threads on the front end that threads into internal threads in the rear end of a front housing portion 17b. A piston 21 reciprocally moves in the housing 17 and moves an actuating rod 22 having a portion in the housing and a portion that extends through and projects beyond the forward end of the housing 17. 
     A rod extension 24 with an enlarged head 25 is secured at the rear end of the piston 21. In particular, the forward end of the rod extension 24 has external threads that thread into internal threads in the piston 21 as seen in FIG. 5. A return spring 26 bears against the inside of the rear end of the housing and head 25 and returns the rod 22 to the extended position when the fluid pressure at the inlet is removed. A fluid inlet portion 27 in the housing is coupled to fluid line 13. Apparatus found suitable for cylinder 15 is a Model RCP-55 sold by the ENERPAC Corporation, Butler, Wis. 
     An outer free end portion of the piston rod 22 has a neck 28 inset a selected distance from its terminal end to provide a set of opposed inwardly facing, radially extending arcuate retaining surfaces 29 that span arcs of about 80 degrees. The rod has a pair of oppositely disposed axially and circumferentially extending channel-like grooves 31 each spanning an arc of about 100 degrees. 
     A removable or detachable die holder 35 removably or detachably mounts on the end of the rod 22. Holder 35 has a cylindrical main body 36 with a central axial throughbore 37 and a radial slot 38 which slidably receives a pair of oppositely disposed radially extending keepers 39. When the holder 35 is on the rod 22 in a fastened position the keepers extend radially into the neck 28 and bear against the retaining surfaces 29 to hold the die holder 35 against axial movement on the rod for one angular position for the die holder. The grooves 31 are slightly wider than the width of the ends of the keepers 39 which permit the holder to be rotated 90 degrees about its longitudinal axis so that when the opposed keepers 39 are in alignment with the opposed grooves 31 and the holder 35 can be axially slid off the end of the rod for removal. Similarly, the keepers are aligned with the grooves to enable the die holder to slide on the rod after the rod is inserted through the holes in the pieces. A retaining plate 41 is secured to the front end of the main body 36 by four bolts 42. These bolts extend through holes in the plate, into holes 39a in the keepers and thread into the main body 36 to hold the keepers in place. The main body is provided with an internally threaded radial bore 44 which receives a ball 45, spring 46 and set screw 47 to releasably lock the main body to the rod 22. The rod 22 is provided with an annular groove 48 into which the ball 45 is forced by the set screw 47. 
     A first die 51 has a cylindrical body with a central axial throughbore 52 having an internal diameter sized to receive a male portion of a second die 57 described hereinafter. Further the internal diameter of the throughbore 52 is greater than the external diameter of the rod 22 to slidably receive the rod 22. A step in the main body provides a rear end portion 53 of reduced diameter that will insert into an opening in the front housing portion 17b. The first die 51 has a flat radially extending end surface 54. A pair of opposed set screws 55 extend through holes in the housing and the first die 51 to releasably secure the first die to the housing 17. 
     The second die 57 has a cylindrical main body portion with a central axial throughbore 59 and has a tapered inner male section 61 of less diameter than the main body portion that increases in diameter from an inner end toward an outer end to provide a tapered surface 60 at a selected angle A with the horizontal axis shown as about 12 degrees and further has an arcuate section 62 formed along a selected radius designated R which is an extension of the male section 61. Typically radius R is about 1/8 inch. A set screw 63 extends through holes in body 58 and main body 36 to secure the swaging die to the rear end of die holder 35. 
     In use, a hollow fastening section 67 is provided. The fastening section has an end flange 68. This fastening section 67 may be made by using a short length of metal pipe and a set of dies similar to dies 51 and 57 above described and forming the flange 68 by having the two dies brought together under pressure. The fastening section 67 is inserted into aligned holes 71 and 72 in pieces to be fastened shown as portions of two sheets 73 and 74, respectively, to be joined. The sheets shown are of the same thickness but it is understood that in many instances the sheets will have different thicknesses. Further these sheets in a building are frame panels, gussets and trusses as described fully in the above mentioned copending application. 
     The actuating rod without the die holder 35 and second die 57 is inserted into the fastening section and holes in the sheets and the free end of the fastening section 67 projects beyond the holes. The die holder 35 is attached to the free end portion of rod 22 and set screw 47 tightened as above described. The cylinder assembly 15 is actuated to cause the rod 22 to retract causing the second die 57 to move against the fastening section to compress the ends of the fastening section 67 between the two dies to form a rivet-type fastener 77 with a flange 78 that fastens the two sheets together. Once the fastener 77 is formed the pressure to the cylinder is released, the return spring 26 automatically moves the rod 22 to a return extended position. 
     As seen in FIGS. 7 and 8 in the flange forming process to make fastener 77, the tapered male section 61 is received in the throughbore 59 of the first die 51. The fastening section 67 rides first against the tapered surface 60 of the male section 61 and then the surface of the arcuate section 62 so as to roll or curl the hollow fastening section radially out and form a hollow, smooth, curved, or cold rolled flange 78 having a substantial flange gripping surface area 78c that bears against the exterior rounded surface of the adjacent piece 73. At the same time, the other curled flange 68 is further flattened against the other sheet 74. The flange 78 gradually decreases in thickness in a radial direction toward an outer peripheral edge 78a. The flange has outside surface 78b that extends along the exterior surface of the adjacent piece being fastened and a convexly curved inside edge 78c defining the hole through the fastener extending along the same radius of curvature as surface 76b. 
     The rivet-type fastener 77 so formed has a relatively large inside diameter in comparison to the thickness of the sheets being joined. An example for the sheets is sheet metal in the range of 0.03 to 0.06 inches with the hole in the fastener being 1 inch and the outside diameter about 1.05 inches so that the thickness of the fasteners is about 0.05 inches. The radial dimension of the flange is about 0.25 inches. A suitable range is 0.20 to 0.50 inches. The ratio of the diameter of the hole in the fastening section to the thickness of the pieces then is about 4 to 1 to 15 to 1 and preferably on the order of 8 to 1. 
     A typical fastener will have an internal dimension of at least four times the combined thickness of the pieces being fastened and a thickness of at least substantially equal to the thickness of the thickest of the two pieces. This provides a substantial flange gripping surface area so as to avoid shear of the pieces and prevent the flange from deforming under load. 
     Referring now to FIGS. 13 and 14 there are shown two pieces which are of a first sheet 81 with a hole 82 and a second sheet 83 with a fastening section 84 that is an extension of sheet 83 forms a hole 85 with fastening section 84 extending through and projecting beyond hole 82. In practice the fastening section 84 is made by using a male punch die to punch through the sheet 83 leaving a tubular fastening section 84 integral with the sheet and the free end is used to form the fastening flange. The fastener flange 88 has a peripheral edge 88a, curved outside surface 88b and convexly curved inside edge 88c defining the hole through the fastened pieces. The first die 86 on the housing 17 and the second die 87 on the die holder 35 is moved by the rod 22 in the same manner as above described to form a rivet-type fastener 87 with a flange 88 to fasten the sheets together. 
     Although the present invention has been described with a certain degree of particularity, it is understood that the present disclosure has been made by way of example and that changes in details of structure may be made without departing from the spirit thereof.