IL117029A - Connector for joining a structural member thereto and a method for fabrication thereof - Google Patents

Abstract

A cold forming method for fabricating a connector (10) from a flat metal sheet, the method comprising the steps of: (a) forming a circular disc (12) from said metal sheet; (b) forming a crucible from said disc, said crucible having a hemi-spherical base; (c) forming a truncated sphere from said crucible, said truncated sphere having a circular aperture; and (d) drilling a plurality of holes (14) within the surface of said truncated sphere. 1297 כ" ג בסיון התשס" א - June 14, 2001

Description

A CONNECTOR FOR JOINING A STRUCTURAL MEMBER THERETO AND A METHOD FOR FABRICATION THEREOF m* fi*>> o»3itt o'ttJtt N *)ii r) untt Eitan, Pearl, Latzer & Cohen-Zedek P-854-IL FIELD OF THE INVENTION The present invention relates to structural systems and more specifically to a connector for joining space frame structural members together.

BACKGROUND OF THE INVENTION Structural systems commonly use space frames to enclose a large area. Space frames are used functionally in gymnasiums, auditoriums and exhibition halls to provide large open spaces. Structural space frames are also used in canopies and skylight supports to provide aesthetically pleasing structures.

One of the advantages of space frames is their modularity which allows for prefabrication of standard components and speedy erection. Generally, space frames are constructed from standardized members linked together by a connector or node.

Various types of connectors are known and used for space frame structures. For example, the Ben-Ezra Kargola company of Kfar Sava in Israel manufactures a generally flat ("BAK") connector, which allows up to eight main structural members to be connected together. Though relatively simple to manufacture and use, the flat "BAK" connector does not have the versatility of a spherical connector. 1 854conn.IL In order to fully exploit the potential of space frame structures, spherical connectors have been developed. The TM Truss' manufactured by Taiyo, Kyogo Corporation of Japan uses a generally spherical steel globe containing a multiplicity of pre-drilled and pre-threaded apertures for connecting steel pipe members to form a space frame structure. Each of the steel members comprises a bolt having a matching threaded end for screwing into the globe.

The "Spherobat" system, manufactured by Aluminum Pechiney of France, consist of connecting specially prepared pipes to spherical nodes containing a multiplicity of holes through which a bolt is inserted. The special pipes comprise forged cones, having threaded holes, welded to the end of the pipes to accommodate the assembly bolting process.

Both of the above prior art systems using spherical node connectors are expensive to manufacture and complicated to assembly. 2 854conn.IL SUMMARY OF THE PRESENT INVENTION It is an object of the present invention to provide a connector for use in modular space frame structures which overcomes the limitations and disadvantages of prior art connectors..

It is a further object of the present invention to provide a method for manufacturing a space frame connector which overcomes the limitations and disadvantages of prior art methods.

There is therefore provided, in accordance with a preferred embodiment of the present invention, a cold forming method for fabricating a connector from a flat metal sheet. The method includes the steps of forming a circular disc from the metal sheet; forming a crucible from the disc, the crucible having a hemi-spherical base, forming a truncated sphere from the crucible, the truncated sphere having a circular aperture; and drilling a plurality of holes within the surface of the truncated sphere.

Additionally, in accordance with a preferred embodiment of the invention there is provided a cold forming method for fabricating a connector from a flat metal sheet. The method includes the steps of forming a pair of hemi-spherical crucibles from the metal sheet, connecting the pair of hemispherical crucibles together to form a sphere, truncating the sphere and drilling a plurality of holes within the surface of the truncated sphere. 3 854conn.IL Furthermore, in accordance with a preferred embodiment of the invention the methods further includes the steps of connecting at least one structural member to the fabricated connector, the least one structural member constructed from hollow section elements, connecting a threaded nut to the inner face of the hollow section elements and fitting a threaded bolt to the threaded nut.

Additionally, in accordance with a preferred embodiment of the invention there is provided a connector for joining at least one structural member thereto. The connector includes a hollow truncated sphere having a circular aperture and a plurality of holes formed within the surface of the hollow truncated sphere. The distance from the center of the circular aperture to the center of the truncated sphere is less than the radius of the truncated sphere.

Furthermore, in accordance with a preferred embodiment of the invention the connector further includes a flat cap connected to the circular aperture for sealing and strengthening the connector.

Furthermore, in accordance with a preferred embodiment of the invention the connector further includes a means for fastening structural members to the connector.

Furthermore, in accordance with a preferred embodiment of the invention the fastening means includes a threaded nut connected to the inner face of the hollow section elements and a threaded bolt dimensioned to fit into the threaded nut.. 4 854conn.IL Additionally, in accordance with a preferred embodiment of the invention there is provided a space frame structural system which includes a connector and at least one structural member. The space frame structural system also includes means for fastening the at least one structural member to the connector and a flat cap connected to the circular aperture for sealing and strengthening the connector. The distance from the center of the circular aperture to the center of the truncated sphere is less than the radius of the truncated sphere.

Furthermore, in accordance with a preferred embodiment of the invention, the structural members include hollow section elements. 5 854conn.IL BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which: Fig. 1 is a perspective view illustration of a connector, constructed and operative in accordance with a preferred embodiment of the present invention; Fig. 2 is a cross-sectional illustration of the connector of Fig. 1 coupled to a plurality of structural members; Fig. 3 is an exploded cross-sectional illustration of the connector and structural members of Fig. 2; Figs. 4A, 4B, 4C and 4D are sectional illustrations of the method of manufacture of the connector of Fig. 1 , constructed and operative in accordance with a preferred embodiment of the present invention; Fig. 4E is a flow chart diagram illustration of the manufacturing steps for the connector of Fig. 4; Figs. 5A, 5B, 5C and 5D are sectional illustrations of the method of manufacture of the connector of Fig. 1 , constructed and operative in accordance with a further preferred embodiment of the present invention; and Fig. 5E is a flow chart diagram illustration of the manufacturing steps for the connector of Fig. 5. 6 854conn.IL DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Reference is made to Figs. 1 , 2 and 3. Fig. 1 illustrates in perspective view a connector 10, constructed and operative in accordance with a preferred embodiment of the present invention. Fig. 2 is a cross-sectional illustration of a coupling system utilizing the connector 10, constructed and operative in accordance with a preferred embodiment of the present invention. Fig. 3 is an exploded cross-sectional illustration of the connector and structural members of Fig. 2.

Connector 10 is a generally hollow truncated sphere, that is connector 10 is spherical in shape having an archoid section removed, thus leaving a circular aperture 12. Connector 10 is fabricated by cold forming from metal such as steel or other suitable material capable of withstanding the expected loads. Connector 10 further comprises a plurality of holes 14 within the truncated sphere. As shown in Fig. 2, connector 10 is coupled to a plurality of frame members 16 by means of bolts 18 inserted through holes 14.

Frame members 16 are generally hollow section elements, preferably, tubular or cylindrical in cross-section. A threaded nut 20 is welded, or otherwise attached, to the inner face 22, proximate to each end 24 of frame members 16. Bolts 18 are threaded and dimensioned to fit the threaded nut 20.

Since, the system only requires three separate elements, a connector 10, frame members 16 and bolts 18, a space frame structure, for example, can be easily assembled. 7 854conn.IL The use of a threaded nut 20 within the hollow section of the frame members 16 facilitates the assembly of frame members 16 to a connector 10. To connect a frame member 16 to the connector 10, frame member 16 is offered up to the connector 10 in line with one of the holes 14. A bolt 18 is inserted, via circular aperture 12 into the hollow space of the connector 10. The bolt 18 is then placed in the appropriate opening 14, and fastened to frame member 16. The circular aperture 12 facilitates the entry of a spanner, or other fastening tool, to be used for fastening the bolt 18.

It will be appreciated by persons skilled in the art that the circular aperture 12 allows for a large number of frame members to be easily attached to the connector 10, and the number of frame members 16 is only limited by the size of the connector 10 and the diameter of the frame members 16 themselves. Furthermore, the system allows the frame members 16 to assume variable angles.

Connector 10 further comprises a cap 30 and a fastening bolt 32. The cap 30 closes off the connector 10 ensuring that the base and top row of the structural frame members 16 have a flat surface 34 for the fixing of a covering, for example. Cap 30 strengthens the aperture 12 and upper section of connector 10 against the axial forces induced by frame members 16. Cap 30 also ensures that the connectors 10 are sealed from ingress of dust, dirt and the elements. As can be best seen in Fig. 2, the sphere is truncated at a distance d1 from the axis line l-l. The distance d, is generally greater than the radius (d2) of the frame members 16. 8 854conn.IL A best seen in Fig. 3, cap 30 is a generally flat disc, circular in cross-section, having a threaded circular aperture 36 formed in the center thereof. In order to ensure that cap 30 is closely fitted to the connector 10, a circular indentation 38 is formed on the inner face 40 of the cap 30 and a nib 42 is formed in the truncated sphere, adjacent circular aperture 12. The nib 42 is dimensioned so as to match the dimensions of the circular indentation 38. It will be appreciated by persons skilled in the art that the method of fitting cap 30 to connector 10 is given for purposes of example only and is not in any way to be construed as thereby limiting.

The opening 44 opposite threaded circular aperture 36 is formed to accept the countersunk head 46 of fastening bolt 32. Fastening bolt 32 is threaded and dimensioned to fit the threaded circular aperture 36. To secure cap 30 to connector 10, fastening bolt 32 is inserted into opening 44 and screwed into circular aperture 36.

Reference is now made to Figs. 4A - 4E. Figs 4A - 4D are sectional illustrations of the method of manufacture of the connector 10, constructed and operative in accordance with a preferred embodiment of the present invention. Fig. 4E is a flow chart diagram illustration of the steps in the manufacture of the connector 10. Elements having similar functions to the embodiment of Fig. 1 -3 are designated with the same reference numerals.

Fig. 4A illustrates a circular disc 110 having a diameter "D". A hole 112 is formed in the center of disc 110, by punching or drilling, for example, to 9 854conn.IL form the opening 44 (step 210). Disc 110 is then curved about axis line IV-IV using any suitable cold forming process, known in the art, such as a cold forming (step 212), to form an axi-symmetrical crucible 114 having a hemi-spherical base of radius R and having two extending straight sides 116, each having a length l2 (Fig. 4B). Sides 116 are then curved, using any suitable cold forming process known in the art, to radius R (step 214 - Fig. 4C), forming the circular aperture 12 and a truncated sphere. A circular flat cap 30 is formed from a metal sheet (step 216), using any suitable cold forming process, known in the art and adapted to fit the aperture 12 of the formed truncated sphere. Finally a plurality of holes 14 are drilled within the spherical surface of the truncated sphere (step 218).

Reference is now made to Figs. 5A - 5D which illustrate an alternative method of manufacture of the connector 10, constructed and operative in accordance with a preferred embodiment of the present invention. Fig. 5E is a flow chart diagram illustration of the steps in the manufacture of the connector 10 according to method of Figs. 5A-5D. Elements having similar functions to the embodiment of Fig. 1 - 4 are designated with the same reference numerals.

Fig. 5A illustrates a circular disc 110 having a diameter "D". A hole 112 is formed in the center of disc 110, by punching or drilling, for example, to form an opening 44 (step 250). Fig. 5B is a sectional illustration of two identical hemi-spherical crucibles 310a and 310b. Crucibles 310a and 310b are formed in a similar manner to step 210 of the embodiment of Fig. 4, that is, by any suitable cold forming process known in the art (step 252). The two hemi- 10 854conn.IL spherical crucibles 310a and 310b, respectively, are then welded together, (step 254), or otherwise suitably connected together, to form a sphere 312. The top of the sphere 312 is then removed (step 256) to from the truncated sphere shape of connector 10. As described hereinabove, with respect to Fig. 4D, a circular flat cap 30 is formed from a metal sheet (step 258) and adapted to fit the aperture 12 of the formed truncated sphere and a plurality of holes 14 are drilled within the spherical surface of the truncated sphere (step 260).

It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather the scope of the present invention is defined only by the claims which follow: 11 854conn.IL

Claims (1)

1. CLAIMS ' ft A cold forming method for fabricating a connector from a flat metal sheet, the method comprising the steps of: a. forming a circular disc from said metal sheet; b. forming a crucible from said disc, said crucible having a hemispherical base; c. forming a truncated sphere from said crucible, said truncated sphere having a circular aperture; and d. drilling a plurality of holes within the surface of said truncated sphere. A cold forming method for fabricating a connector from a flat metal sheet, the method comprising the steps of: a. forming a pair of hemi-spherical crucibles from said metal sheet; b. connecting said pair of hemi-spherical crucibles together to form a sphere; c. truncating said sphere; and d. drilling a plurality of holes within the surface of said truncated sphere. A method according to any of claims 1 - 2 and further comprising the steps of: 12 854conn.IL a. connecting at least one structural member to said fabricated connector, said least one structural member constructed from hollow section elements; b. connecting a threaded nut to the inner face of said hollow section elements; and c. fitting a threaded bolt to said threaded nut. A connector for joining at least one structural member thereto, said connector comprising: a. a hollow truncated sphere having a circular aperture; and b. plurality of holes formed within the surface of said hollow truncated sphere; c. wherein the distance from the center of said circular aperture to the center of said truncated sphere is less than the radius of said truncated sphere. A connector according to claim 4 further comprising a flat cap connected to said circular aperture for sealing and strengthening said connector. A connector according to any of claims 4 and 5 further comprising means for fastening said at least one structural member to said connector. 13 854conn.IL A connector according to any of claims 4 - 6 and wherein said at least one structural member comprises hollow section elements. A connector according to claim 7 and wherein said fastening means comprises: a. a threaded nut connected to the inner face of said hollow section elements; and b. a threaded bolt dimensioned to fit into said threaded nut. A space frame structural system comprising: a. a connector wherein said connector comprises a hollow truncated sphere comprising: i. a circular aperture; and ii. a plurality of holes formed within the surface of said hollow truncated sphere; b. at least one structural member; c. means for fastening said at least one structural member to said connector; and d. a flat cap connected to said circular aperture for sealing and strengthening said connector, wherein the distance from the center of said circular aperture to the center of said truncated sphere is less than the radius of said truncated sphere. 14 854conn.IL A space frame structural system according to claim 9 and wherein said at least first and second structural members comprise hollow section elements. A space frame structural system according to any of claims 9 - 10 and wherein said fastening means comprises: a. a threaded nut connected to the inner face of said hollow section elements; and b. a threaded bolt dimensioned to fit into said threaded nut. A method according to any of claims 1 - 3 and substantially as described hereinabove. A method according to any of claims 1 - 3 and substantially as illustrated in any of the drawings. A connector according to any of claims 4 - 8 and substantially as described hereinabove. 15 854conn.IL 117029/2 A connector according to any of claims 4 - 8 and substantially as illustrated in any of the drawings. 16 854conn.IL