US3447278A

US3447278A - Truss element

Info

Publication number: US3447278A
Application number: US512565A
Authority: US
Inventors: Howard W Collins
Original assignee: Armco Inc
Current assignee: Armco Inc
Priority date: 1965-12-08
Filing date: 1965-12-08
Publication date: 1969-06-03
Anticipated expiration: 1986-06-03

Description

June 3, 1969 Filed Dec. 8. 1965 H. W. COLLINS TRUSS ELEMENT Y @WM gam da.

sheet June 3, 1969 H, w, @LLMv 3,447,278

TRUSS ELEMENT Filed Dec. 8, 1965 sheet 2 ors BY guar/.ZL

H. W. COLLINS June 3, 1969 TRUSS ELEMENT Sheet Filed Dec. 8, 1965 INVENTOR How/112D W COLL/N5,

United States Patent O U.S. Cl. 52-694 1 Claim This invention relates to `a novel method and apparatus for continuously producing truss elements.

Generally considered, and as used in this application, the term truss element is used to indicate a truss member having one or more substantially linear metal chord members, with a supporting web secured thereto. According to the prior art, a' joist was a self-suicient member; that is, it had a top and a bottom chord carrying respectively the compression and tension forces, and a reinforcing web inbetween. The door or load carrying surface was laid on -top of the joist, and contributed little or nothing to the strength of the composite unit.

The metal top chord member can be eliminated if the joist is permanently attached'to some sort of flooring material, so that the flooring material itself will act as the top chord and carry the compressive load. By way of example, the web can be provided with lugs or a continuous, longitudinal reinforcing wire which may be embedded in a cast concrete floor, or with a toothed plate to be embedded in a plywood lloor, and so forth.

vThese structures of the prior art were customarily manufactured by preforming both the chord and web, cutting these members into appropriate lengths, and then securing them together. This of course involves a plurality of separate steps requiring a large amount of space, 'and making the manufacturing operation relatively slow and expensive.

Accordingly, it is the principal object of this invention to provide a method and apparatus for the continuous manufacture of truss elements without a top chord.

Morespecitically, it is an important object of this invention to provide a method and apparatus which will permit the production of these components at a lower manufacturing cost than has heretofore been possible.

A further object of the invention is the provision of a method and apparatus which will produce truss elements far more rapidly than was possible according to the prior art.

Still another object of the invention is to provide a single apparatus which, in its manufacturing capabilities, is highly flexible. That is, it can be readily utilized to produce varying sizes and lengths of truss elements.

These and other objects of the invention will become apparent to the skilled worker in the art upon reading the following specification, in conjunction with the accompanying drawings.

In the drawings:

FIGURE 1 is a side elevational View of one embodiment of the truss producing lapparatus of this invention;

FIGURE 2 is a perspective view showing a portion of a truss manufactured by the 4apparatus and method of FIGURE '1:

FIGURE 3 is a perspective view showing the forming members of the apparatus of this invention in more detail;

FIGURE 4 is a perspective view showing one lower die half and the pivotal die of the apparatus of this invention;

ICC

FIGURE 5 is a perspective view showing the pivotal die and anvil of the apparatus of this invention;

FIGURE 6 is a perspective view showing the upper welding head of the apparatus of this invention;

FIGURE 7 is a perspective view showing the lower welding head of the apparatus of this invention; and

FIGURE 8 is a perspective view showing one means for advancing the truss element through the apparatus of this invention.

Brieily considered, the instant invention contemplates the feeding of a substantially linear chord in continuous lengths into the truss forming apparatus. A ilat strip of web forming material will simultaneously 'be fed into a position overlying the chord. A portion of the web forming strip is then clamped in position, and a first bend is formed, having legs pointing divergently toward the chord. The clamped portion of the web forming strip will form one of the legs of this tirst bend. The other leg of this rst bend is held in position by the members forming the iirst bend, and a second bend, of equal angle but opposite to the rst bend is formed. This second bend will have legs pointing divergently upward from the chord. This second bend is then secured in any suitable manner to the chord, and the joined web and chord is advanced one unit length.

Referring now momentarily to FIGURE 2, the truss element produced by the apparatus and method of this invention will be described, in order that the various stages of the method may be more fully understood. As briefly indicated before,` the product of this invention includes a generally channel shaped bottom chord 10 having the downwardly extending leg portions 12 and 14. It will also be noted that the upper surface of the chord 10 may be provided with the raised ribs 16, for a purpose to be described hereinafter. The web which will lbe secured to the chord member 10 is indicated generally at 18. The space between the dashed lines 20 and 22 form what may be considered one unit length of truss. Of course, one unit length is also equal to the longitudinal distances between the apexes of successive angles 24 or 26. The web within this unit length of truss includes the pair of spaced apart, equal but opposite angles 24 and 26. The angle or bend 24 includes the

legs

28 and 30 which point divergently upward, while the angle or bend 26 includes the

legs

30 and 32 pointing divergently toward the chord 10. It will be apparent that the leg portion 30 in fact extends between the angles or bends 24 and 26.

It will also be noted that the portions of the web extending between the successive angles are concave upward, in order to increase the rigidity of the structure. The bends 24 and 26 themselves include the flat portions 34 yand 36 respectively. The at 34 permits the web to be secured as by welding to the chord 10, while the at 36 may be used to mount any one of a number of members to assist in securing the joist of this invention to suitable ilooring materials.

In FIGURE 1, the apparatus of this invention has been shown somewhat diagrammatically. At the far right of this iigure 'are the reels 38 and 40 which contain respectively a supply of web forming strip and chord forming strip. The flat strip from the reel 38 is passed through the roll former indicated generally at 42 to form the cross section clearly shown in FIGURE 2. Discrete lengths of chord could be formed in a separate operation without interfering with the continuous operation of this device. The chord channel is then intermittently progressed through the ydevice as will be described hereinafter.

A at, somewhat narrower strip from the reel 40 (this strip is subsequently formed into the web) passes to the strip feeder indicated generally at 44, and into the loop 46. This loop provides slack for intermittent gravity feed without accurately `running the feed rolls on an intermittent basis.

The forming elements (shown in perspective in more detail in FIGURE 3) include the split lower die 48-48, the pivotal lower die 50, the upper die 52, and the holddown 54.

Each of the lower die halves 48-48 includes the base block 56 provided with the slot 58 which serves as a guide for the upper die as will be explained hereinafter. It also includes the forming block 60, which, in cross section is configured to form one half of the concavity in the web strip. It will also be noted (see FIGURE 4) that the top portion of the forming block `60t includes the fiat 62 which will form the at 36 described earlier at the apex of the bend or angle 26. It will be understood that the split lower die is necessary in order that it may be withdrawn laterally of the joist being formed. This permits substantially linear motion of the formed web, and of the joined web and chord. That is, if a single lower die block were used, it would be impossible to withdraw it laterally in a straight motion, because of the concave section formed.

Lateral movement of the lower die halves 48 and 48' is -accomplished respectively by the hydraulic cylinders 64 which are conventionally mounted and connected to a suitable source of hydraulic fluid. It will be understood that pneumatic, hydraulic, or other actuating means are interchangeable.

The hold-down 54 is reciprocable vertically by means of the cylinder 66, and is configured to mate with the left hand slope of the forming blocks 60-60 as seen in FIGURE 3.

Similarly, the upper die 52 is vertically reciprocable `by means of the cylinder 68, and is provided with convex faces which mate respectively with the right hand portions of the forming blocks 60-60 (again as seen in FIGURE 3) and the pivotal die 50 to be described presently. The upper die is provided `with the laterally extending tongues 70, which are adapted to slide in the guide slot 58-58' of the lower die halves. The upper die is also provided at its .apex with the flat forming member 72 which, in conjunction with the anvil 74 serves to form the flat '34 described above.

The anvil 74 of the apparatus is necessary to prevent deformation of the raised ribs 16 :of the lower chord. To this end, its lower surface is provided with mating indentations.

As seen in FIGURES 4 :and 5 the pivotal die 50 includes the mounting tongues 76 which will be pivotally mounted as at 78 at a point below the pass line of the chord. It is pivotally moved by means of the hydraulic cylinder 80. By virtue of the pivotal construction just described, it will be observed that the lowermost edge of pivotal die 50 describes an arc indicated by the arrow 82 (FIGURES 4 and 5) in carrying out its forming stroke. This motion tends to pinch the web forming strip down against the anvil 74 to form the flat 34.

Reviewing the operation of the components described thus far, the lower die halves 48418' will move by the cylinders 64 into face to face contacting relation. The hold-down 54 is then moved downwardly to clamp a portion of the web (eg. leg into place between the left hand edge (as seen in FIGURE 1) of the forming blocks `60-60' and the hold-down itself. At this time, the upper or male die comes down, forming the angle or bend 26 described above, and forming the concavity in the

leg

28 or 32. This also serves to form the flats 34 and 36. At this time, the cylinder 80 is actuated to pivot the die 50 up into a position against the right hand edge (as seen in FIGURE l) of the upper or male die, thereby 4 forming the angle or bend 24 and the concave cross section of the leg 30.

At this time, the pivotal `die returns to its initial position, the male die lifts, the hold-down lifts, the lower die halves separate, and means can be provided to move the unit as thus formed, forward one unit length.

In the preferred form of the invention, the securing of the web 18 to the chord 10 is accomplished during the foregoing operation. To this end, a resistance welding head 84 is provided which is laterally movable into a position overlying each successive at 34. The welding head 84 will be moved into the position overlying the ilat by means of the cylinder 86, and once in position, it is forced downwardly a fixed distance by the cylinder 88. At this time, the bottom welding electrode is forced upwardly as by means of the cylinder 92 with a constant pressure, so that the lweld is pressed together during fusion. The longitudinal ribs 16 form projections which concentrate welding current for efficient welding. Projections could also be formed on the ats 34 for the same purpose. Although this welding operation can be done in other ways, the above method utilizes simple block electrodes, and gives a metallurgically and mechanically sound connection.

It will now be apparent that since this weld is accomplished during the forming operation described above, a single means can easily be constructed to ladvance, both the web and chord a unit length. This can conveniently be accomplished as shown in the drawings by means of the indexing ratchet mechanism indicated generally at 94 in FIGURE 8. This mechanism includes the finger 96 which is pivotally mounted as at 98 and movable to a position engaging the web at the weld point. The entire indexing mechanism is movable by means of the hydraulic cylinder 100 longitudinally a distance of one unit length. Therefore, after the upper or male die 52 and hold-down 54 have lifted, and the lower die halves 4848 have been moved laterally, the indexing mechanism may engage the truss element at the wel-d point, and move it forward one unit length. The entire operation may then be repeated, so that the truss element is continuously manufactured.

In some cases, if the angle of the diagnols in the web is shallow enough, the female pivotal die for the back leg can be replaced by a fixed portion of the sliding die halves 48-48, or by a one-piece stationary die.

It is believed that the foregoing constitutes a full and complete disclosure of the invention. Numerous modifications may be made without departing from the scope and spirit of this application. For example, it may be desirable under some conditions to relocate the welding apparatus at the position intermediate the pivotal die 50 and the lower die halves 60-60 where the apex of the upper die strikes the anvil. Of course, a suitable opening in the lower die half would be provided. Hence no limitations are to be inferred except as specifically set forth hereinafter.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A truss element comprising,

a linear lower chord member, said chord member being channel shaped in cross section and having a base :and downwardly exten-ding legs on either side of said base;

two spaced parallel longitudinally extending ribs projecting upwardly from said base;

a supporting web secured to said base, said web comprising a strip of metal having in succession a plurality of equal but opposite bends, the portions of said strip intermediate of said bends being concave upwardly,

each of said bends including a flat portion parallel to said base, alternate at portions being resistance welded to said ribs.

(References on following page) References Cited UNITED FOREIGN PATENTS 592,984 2/ 1960 Canada. STATES PATENTS 73,318 6/1960 France.

Ragsdale 52-694 Tarbox 52 694 5 FRANCIS K. ZUGEL, Przmary Examlner. Braden 52-694 U.S. C1. X.R. Keller 52--694 X 52-634

Claims

1. A TRUSS ELEMENT COMPRISING, A LINEAR LOWER CHORD MEMBER, SAID CHORD MEMBER BEING CHANNEL SHAPED IN CROSS SECTION AND HAVING A BASE AND DOWNWARDLY EXTENDING LEGS ON EITHER SIDE OF SAID BASE; TWO SPACED PARALLEL LONGITUDINALLY EXTENDING RIBS PROJECTING UPWARDLY FROM SAID BASE; A SUPPORTING WEB SECURED TO SAID BASE, SAID WEB COMPRISING A STRIP OF METAL HAVING IN SUCCESSION A PLURALITY OF EAUAL BUT OPPOSITE BENDS, THE PORTIONS OF SAID STRIP INTERMEDIATE OF SAID BENDS BEING CONCAVE UPWARDLY, EACH OF SAID BENDS INCLUDING A FLAT PORTION PARALLEL TO SAID BASE, ALTERNATE FLAT PORTIONS BEING RESISTANCE WELDED TO SAID RIBS.