US3626567A

US3626567A - Method and apparatus for manufacturing structural semijoist

Info

Publication number: US3626567A
Application number: US32645A
Authority: US
Inventors: Anatol Michelson; Robert W Cruger
Original assignee: Gulf & Western Ind Prod Co
Current assignee: BLISS-SALEM Inc A CORP OF; Gulf & Western Ind Prod Co; GULF and WESTERN INDUSTRIAL PRODUCTS Co
Priority date: 1970-04-28
Filing date: 1970-04-28
Publication date: 1971-12-14
Anticipated expiration: 1988-12-14

Abstract

AN APPARATUS AND METHOD FOR PRODUCING PARTIAL STRUCTURAL GIRDERS OR SEMIJOISTS FROM TWO ELONGATED STRAND MEMBERS BY FORMING ONE STRAND MEMBER INTO A V-SHAPED CONFIGURATION WITH AN APEX, WHICH APEX CONTACTS THE SECOND STRAND MEMBER, AND IS JOINED THERETO. THE FIRST STRAND MEMBER IS FIXEDLY SUPPORTED AT TWO PRESELECTED END POINTS BY TWO SUPPORT MEANS WHILE A POWER FORMING MEANS, OPERATIVE THROUGH A PREDETERMINED DISTANCE, OPERATES AGAINST THE STRAND TO FORM AND STRETCH IT INTO THE V-SHAPED CONFIGURATION. MOVEMENT OF THE POWER FORMING MEANS FORCES ONE SUPPORT MEANS TOWARDS THE OTHER DURING THE FORMING OPERATION. AT THE BOTTOM OF THE FORMING STROKE, THE APEX OF THE V-SHAPED CONFIGURATION CONTACTS THE SECOND STRAND MEMBER AND IS JOINED THERETO BY JOINING MEANS. THIS PROCESS IS REPEATED UNTIL A SEMIJOIST IS COMPLETED HAVING A SUCCESSION OF V-SHAPED CONFIGURATIONS.

Description

5 Sheets-Sheet 1 ROBERT W. CRUGER Dec. 14, 1971 M|CHELSON ET AL METHOD AND APPARATUS FOR MANUFACTURING STRUCTURAL SEMI-ICIST Filed April 28. 1970 ATTORNEYS Dec. 14., 1971 A, M|CHEL5ON ETAL 3,626,567

METHOD AND APPARATUS FOR MANUFACTURING STRUCTURAL SEMTJOIST Filed April 28, 1970 5 Sheets-Sheet 2 FIG. 2

INVENTORS. ANATOL MICHELSON BY ROBERT W. CRUGER MW, mma M,

ATTORNEYS Dec. 14, 1971 A M|CHELS0N ETAL 3,626,561

METHOD AND APPARATUS FOR MANUFACTURING STRUCTURAL SEMIJOIST Filed April 28, 1970 5 Sheets-Sheet 5 "maven/Tolles. ANATOL MICHELSON BY ROBERT w. CRUGER ATTORNEYS Dec. 14., 1971 A M|CHEL5QN ETAL 3,626,567

METHOD AND APPARATUS FOR MANUFACTURING STRUCTURAL SEILJOIST Filed April 28, 1970 5 Sheets-Sheet 4 Lun- 4 INVENTORS.

ANATOL MICHELSON FIG 5 ROBERT w. CRUGER Zw, mm, M4,

ATTORNEYS Dec. 14, 1971 A M|CHEL$ON ET AL l METHOD AAD APPARATUS FOR MANUFACTURING STRUCTURAL SEMIJOIST Filed April 28, 1970 5 sheets-sheet s sfr/m96 92 86 g *Fifi* W FIG.A 8

INVENTORS. ANATOL MICHELSON BY ROBERT w. CRUGER FIG? Mega, Wmady ATTORNEYS United States Patent ftice 3,626,567 Patented Dec. 14, 1971 U.S. Cl. 29-155 20 Claims ABSTRACT F THE DISCLOSURE An apparatus and method for producing partial structural girders or semijoists from two elongated strand members by forming one strand member into a V-shaped configuration with an apex, which apex contacts the second strand member, and is joined thereto. The tirst strand member is fixedly supported at two preselected end points by two support means while a power forming means, operative through a predetermined distance, operates against the strand to form and stretch it into the V-shaped contiguration. Movement of the power forming means forces one support means towards the other during the forming operation. At the bottom of the forming stroke, the apex of the V-shaped configuration contacts the second strand member and is joined thereto by joining means. This process is repeated until a semijoist is completed having `a succession of V-shaped contigurations.

This application pertains to the art of structural elements and more particularly, to a type of structural girders known in the art as joists.

The invention is particularly applicable to the manufacture of semijoists or incomplete joists, and it will be described with particular refe-rence thereto. However, it will be appreciated by one skilled in the art that the invention has broader applications and can be used for forming various elements composed of two or more joined elongated elements.

For a number of years one of the most commonly used structural girder has been the joist which is formed from two parallel generally 'straight strand members with an undulating strand member joined therebetween. The semijoist is identical to the joist except for the fact that only one straight strand member is initially employed. With the increase in use of these joists due to ever increasing demand for new buildings, it has become necessary to manufacture these joists in increased numbers with increased dimensional stability.

A variety of machines for the manufacture of joists are now being used. Prior machines, however, experienced certain disadvantages. The most apparent of these disadvantages has been that the early machines used complicated designs and relatively expensive components. Mo-re importantly, prior machines did not adequately account for certain metal working characteristics. When a material is deformed from its natural shape, it has a tendency to spring-back towards its original shape. This characteristic occurs because the material is deformed partly through the elastic region and not totally through the plastic region. The result of this type of operation was that prior joists often were dimensionally unstable and unreliable, especially after being installed. Further, these prior machines often required three steps to form the completed joists, i.e., forming an undulating strand at one station vand transporting it elsewhere to be joined, in separate operations, with the straight strands. This, of course, required increased oor space and lowered plant productive capacity.

The present invention contemplates a new method and apparatus to manufacture semijoists for conversion into joists, which method and apparatus overcome all of the above-mentioned disadvantages and other disadvantages associated with prior machines. Additionally, the present invention provides a method and apparatus which are technically less complicated, more flexible in operation, and more readily serviceable.

In accordance with one aspect of the present invention, there is provided an apparatus for forming a semijoist which includes rst and second means for supporting a length of an elongated lirst, or webbing, strand member and means for supporting an elongated second, or chord, strand member in a predetermined relationship adjacent to and spaced from each other. A power forming means is located generally between the tirst strand member supports, on the opposite side of the tirst strand. The power forming means and the first and second means for supporting operate in conjunction with each other to form generally V-shaped configurations in the lirst strand which is driven into physical contact with the second strand at a predetermined position. As the first strand is brought into physical contact with the second strand, they are automatically joined together to form a partial semijoist which is then automatically advanced in order that the apparatus may re-cycle and produce a succession of these formed and joined sections.

In accordance with still another aspect of the present invention, a method is provided for forming semijoists. This method includes the steps of supporting a length of an elongated first, or webbing, strand member on first and second supporting means; supporting an elongated second, or chord, strand member in a predetermined relationship adjacent to and spaced from the lirst strand member; power forming the first strand member into a generally V-shaped configuration with au apex in physical contact with the second member at the apex; joining the irst and second strand members at their point of contact; and, automatically advancing the partially completed semijoists in order that the method may be repeated.

The principal object of the invention is to provide a method and apparatus for manufacturing a structural semijoist.

An additional object is to provide a method and apparatus for manufacturing a structural semijoist, which method and apparatus prevent deformation of one member with respect to the other members of the semijoist.

Another object is to provide a method and apparatus for manufacturing structural semijoists, which method and apparatus avoid the undesirable metal working characteristics of spring-back and Sunburst encountered in prior apparatus and methods.

The invention further contemplates providing a method and apparatus for manufacturing a structural semijoist, which method and apparatus allow for positive location to eliminate substantial differences in dimensions of the semijoist.

A still further object is to provide a method and apparatus for manufacturing a structural semijoist wherein there is used a single unit to perform the desired operations.

The invention may take physical form in certain parts and arrangements of parts, a preferred embodiment of which will be described in detail in this specification and illustrated in the accompanying drawings which form a part hereof and wherein:

FIG. 1 is a side elevational view of the apparatus for the manufacture of semijoists of structural frames;

FIG. 2 is a plan view through the apparatus of FIG. 1 taken along line 2 2;

FIG. 3 is a cross-sectional view through the apparatus of FIG. 1 taken along line 3--3;

FIG. 4 is a cross-sectional view of the apparatus of FIG. 1 taken along line 4 4;

FIG. 5 is a cross-sectional view of the apparatus of FIG. 1 taken along line S-Sg FIG. 6 is a plan view of the joining operation shown in FIG. 5;

FIG. 7 is an end view of the apparatus of FIG. 1 from line 7 7; and,

FIG. 8 is a second embodiment of the view shown in FIG. 4.

Referring now to the drawings wherein the figures are for the purpose of illustrating the preferred embodiment of the invention only and not for the purpose of limiting same, FIG. 1 shows an apparatus for manufacturing a semijoist which apparatus includes a second support and work preparation means A, power forming means B, first support and clamping means C, second strand support means D, strand input table E, and semijoist output table F. In accordance with the illustrated embodiment of the invention, two semijoists are formed simultaneously. It is appreciated that the number of these components can be changed to produce any number of semijoists in a sideby-side fashion without departing from the intended spirit and scope of the present invention.

In accordance with the illustrated embodiment of the invention, second support and work preparation means A is comprised of carriage 2 mounted in relation to main apparatus frame 4 and positioned by

cam followers

6 and 7 conveniently mounted to carriage 2 which operates between cam follower tracks 8 and 9 to allow carriage 2 longitudinal travel in a direction formed by the operation of cam followers 6 a-nd 7 within tracks 8 and 9. Track mounting brackets 10 are used to mount and position tracks 8 and 9 with respect to main apparatus frame 4 and the other components of the apparatus.

Tabs

11 and 12 are welded on opposite sides of carriage 2 and have tapped

holes

14 and 16 therein which are directed coextensive to carriage 2 travel in order to receive home position

carriage adjustment bolts

18 and 20.

Nuts

26 and 28 in conjunction with

adjustment bolts

18 and 20 provide a position locking means for

bolts

18 and 20.

Stop blocks

30 and 32, best shown in FIG. 3, are mounted directly to track mounting brackets 10 and these blocks, in conjunction with

tabs

11 and 12 and

adjustable bolts

18 and 20 determine a home position for carriage 2.

Tabs

34 and 36 are welded to opposite sides of carriage 2 and are drilled and tapped to receive

standard bolts

38 and 40 in order to facilitate adjustable stopping means for the forward position of carriage 2.

Nuts

42 and 44 are provided to act as position locking means for

bolts

38 and 40. Fluid cylinder 46 is mounted to frame 4 and contains rod end 48 which engages tab 50 to provide a return means for returning carriage 2 to the home position. Mounted to carriage 2 is die 56 to provide an end support for the first strand members and to aid in the formation of the semijoists.

Work crimping

means

58 and 60 are adjustably mounted on carriage 2 and are used for reducing the bending strength of rst strand 500. FIG. 4 depicts a detailed drawing of crimping means S8, means 60 being identical thereto. In FIG. 4, crimping means housing 62 is provided with a male dovetail way 64. A corresponding female Way 66 is positively positioned by key 88 and permanently axed to carriage 2. Conditioning dies 70 and 72 are floatingly mounted within housing 62 and are actuated in conjunction with each other by end mounted

cylinders

73 and 74 to perform the preparation work. Die 70 has two longitudinal female recesses 75 of a generally U-shaped cross-sectional configuration and die 72 has two longitudinal anvils 76 of a generally U-shaped cross-sectional configuration, smaller than the recesses 75 in order to be received in recesses 75. Housing cover 78 completes the enclosure of the actual innerworkings to protect them from damage. Crimping means 58 and 60 are longitudinally adjustable along Ways 64- and 66 to allow for a predetermined work distance relationship between die 56 and work preparation means 58 and 60. FIG. l best depicts upper and lower

first strand strippers

80 and 82 affixed to each work preparation means 58 and 60 for maintaining the rst strands in a proper central alignment to prevent them from sticking to either dies 70 or 72 as they are opened and retracted. A second embodiment of the bending strength reducing feature is depicted in FIG. 8 wherein a retaining means generally depicted as 84 in FIG. l is necessarily utilized. Also in FiG. l, this second embodiment, generally comprised of induction heating means 86 and 88, replaces crimping

means

58 and 60. In FIG. 8, using the same permanently mounted female way 66, the

embodiments

86 and 88 each comprise a work preparation induction heater housing 90, housing cover 92,

induction heating elements

94 and 96, and generator 97. This ernbodiment may be used for those first strand members that may not be prepared by crimping

means

58 and 60 because of the type of material or cross-sectional configuration used. In FIG. 3, retaining means 84 comprises a lower clamping means 98, hinged upper clamping means 100, and fluid clamping cylinder 102 and provides retention for the first strands when

embodiments

86 and 88 are employed. A disappearing gauge generally designated 103 is adjustably mounted to carriage 2 and comprises hinged gauge 104, fluid cylinder 106, and adjustable base 108. Fluid cylinder 106 is conveniently mounted to base 108 and to hinged gauge 104, a suggested means being standard clevis and clevis pin connections. Hinged gauge 104 is similarly mounted to base 108. Base 108 is provided with convenient means for adjustable mounting to carriage 2 by. for example, using hex head bolts passing through elongated slots in base 108 into carriage 2.

Power forming means B. as depicted in FIG. l, includes carriage 110 positioned and supported by conveniently mounted standard cam followers 112 in combination with tracks 114. Tracks 114 are mounted directly to frame 4. Fluid power unit cylinder 116 is mounted on mounting and guiding bracket 118 by clevis 120 and clevis pin 122 such that it extends vertically through carriage 110. Rod end 124 of cylinder 116 is threaded to be received in a corresponding threaded hole in die 126. Ultimate length of travel of die 126 is determined by threaded bolt stops 128 and 130, as best shown in FIG. 3, running through carriage 110 into balance bracket 132. The threaded ends receive

nuts

136 and 137 to act as the power unit cylinder stops and

nuts

138 and 139 to act as locking devices for the stops. Mounted between tracks 114 is tab 140 which is provided with a threaded hole to accept bolt 142 for adjustably determining the home position of power forming carriage 110. Nut 144 provides a means for locking adjusting bolt 142 in position. Fluid cylinder 146, mounted directly to frame `4 and longitudinally opposite tab 140, provides a return means for power forming carriage 110 to its home position.

Referring now to FIG. l and FIG. 7, the rst support and clamping means C includes carriage 200 with male dovetail way 202 to be received in a corresponding female dovetail way 204 in plate 206. Plate 206 is stationarily mounted on pedestal 208 which in turn is stationarily mounted to frame 4. Fluid cylinder 210 is positioned by clevis pin 212 which passes through clevis 214 and pedestal 208 to provide the means for longitudinal movement of carriage 200. Carriage 200 is provided with second male dovetail way 216, transverse to way 202. Way 216 is received in corresponding female way 218 included on carriage 220. Conveniently mounted to carriage 220 is die 226 of generally V-shaped crossseclional configuration and a retaining means generally designated 228. Retaining means 228 is comprised of mounting bracket 230, clamp 232, iluid clamping cylinder 234, cylinder mounting pins 236 and 237' and clamp mounting and guid-ing pin 238.

Apertures

240 and 242 in mounting bracket 230 receive

cylinder mounting pins

236 and 237 to maintain clamping cylinder 234 in position. Clamp 232 and rod end 244 of clamping cylinder 234 contain apertures to receive clampl mounting and guiding pin 238.

Arcuate apertures

246 and 248 in mounting bracket 230 guide clamp 232 in its travel. Carriage 220 is powered by uid cylinder 250 which is mounted to the top of way 216 by clevis 252 and clevis pin 254 and secured to carriage 220 by clevis 256 on rod end 258 and clevis pin 260. Positive stop 266 mounted to pedestal 208 determines the absolute home position of carriage 220.

FIG. 5 depicts the joining means, generally designated 299, yused to join the rst and second strand members. It is to be understood that a plurality of these means may be used as required although the disclosure relates to only one of these means. In each joining means, mounting base 300, mounted directly to frame 4, supports the individual means and contains clearance hole 302 in order to receive mounting pin 304. Pin 304 may be adjustably located through the use of set screws 306. Base 307 contains male dovetail way 308 and is permanently mounted to pin 304. Carriage 310, with corresponding female dovetail way 312, is received by way 308. Male dovetail way 318 is mounted on carriage 310 transverse to the cooperation of

ways

308 and 312. Carriage 320, with corresponding female dovetail way 322, is received by way 318 and powered by uid cylinder 324. Cylinder 324 is positioned with respect to carriage 310 by clevis 326 and clevis pin 328 and to carriage 320 by clevis 330 and clevis pin 332. Standard welding gun 336, is mounted to carriage 320 to perform the actual joining and comprises, for example, the General Electric Model 6WGF.

FIG. 1 and FIG. 3 depict second strand member support means D. The support is comprised of U-channel frame 340 positioned longitudinally with respect to frame 4 by mounting pins 342 which are xedly joined to channel 340 and are received in a base channel plate 344. Mounting pins 342 are threaded at the lower extremites to receive adjustment nuts 346 and lock nuts 348. Rollers 350 are mounted by convenient means between channel frame 340, a suggested meansk being by the use of shoulder bolts which pass through apertures 352 in U-channel frame 340 and rollers 350. A disappearing gauge generally designated 358 is mounted to U-channel frame 340 and generally comprises hinged gauge 360, uid cylinder 362, and adjustable base 364. Cylinder 362 is mounted to base 364 and to hinged gauge by clevis and clevis pin means. Hinged gauge 360 is mounted to base 364 by similar means. Base 364 is provided with adjustment means such as, for example, elongated slots and is conveniently mounted to U-channel frame 340 by, for example, using hex head bolts passing through base 364 into frame 340.

OPERATION Before operation may begin, the generally designated components A, B, C and D of FIG. 1 must each be adjusted for a proper overall relationship to the apparatus and each other.

Carriage 2 is adjusted by moving

adjustment bolts

18 and 20 which work in conjunction with stop blocks 30 and 32, such that the distance between die 56 and die 226 is approximately one-eighth to one-half inch less than the total desired leg length of the V-shaped rst strand member 500.

Adjustment bolts

38 and 40 are adjusted to work so that they, in conjunction with stop blocks 30 and 32, stop carriage 2 when it has traveled toward rst support and clamping means C such that the distance between die 56 and die 226 is equal to the desired distance between the extremities of the legs of first strand 500. Crimping means 58 and 60 are next located on carriage 2 such that crimping means 58 is separated by one-half the distance between die 56 and die 226 from die 56 and crimping means 60 is separated by a similar distance from crimping means 58. Base 108 of disappearing gauge 103 is adjusted on carriage 2 such that hinged gauge 104 is three to tive inches to the left of die 56.

The initial position of carriage is determined by adjusting bolt 142 in cooperation with carriage 110 so that the distance between die 226 and die 126 is equal to one-half the distance between dies 226 and 56.

Adjustment nuts

136 and 138 are adjusted to allow for a downward distance travel equal to the desired depth of the V-shaped rst strand member 500.

Adjustment for the iirst support and clamping means C only requires that the cylinder stroke of cylinder 210 be equal to the desired distance between the extreme end portions of the legs of V-shaped strand member 500.

Second strand support means D is adjusted by turning adjustment nuts 346 on mounting pins 342 to bring rollers 350 into proximity with die 126 when it is in its lowest adjusted position. The distance between the plane formed by the top of rollers 350 and the bottom of die 126 should be approximately equal to the thickness of first strand member 500 plus the thickness of second strand member 600. Base 364 of disappearing gauge 358 is adjusted along U-channel frame 340 until hinged gauge 360 is from one to three inches to the left of the vertical center line of die 226.

Joining means 299 must be located relative to the lowest stroke position of power forming means C, i.e., where the rst and second strands come into contact. Each joining means is adjusted by moving pin 304 up or down in mounting base 300 such that when fluid cylinder 324 and welding gun 336 are in the fully extended position, they are within a distance of second strand member 600 whereby 4ultimate weld conditions exist and then locked in that position by set screws 306. Each gun is then located longitudinally -by moving carriage 310 along base 307 until the extended gun is directly below the center line of the apex to be formed, i.e., midway between the nal position of die 56 with respect to die 226. The joining means is then conveniently locked in that position with respect to the remainder of the apparatus.

Following the above-described adjustments, loading the apparatus for operation may begin. Loading and operation will be described with reference to one lirst strand 500 and one second strand 600, although it is to be understood that the preferred embodiment of the apparatus is utilized to manufacture two semijoists simultaneously and that the components may be changed to manufacture any number of semijoists simultaneously. First strand member 500 is fed into the apparatus longitudinally from strand input table E so that the strand passes through crimping means 60, crimping means 58, and open and non-operative retaining means 84, respectively, until it contacts hinged gauge 104 of disappearing gauge 103. Similarly, second strand member 600 is fed from strand input table E along work support means D, being supported thereon by rollers 350, until it contacts hinged gauge 360 if disappearing gauge 358.

Fluid cylinders

73 and 74 of crimping

means

58 and 60 are energized to bring conditioning dies 70 and 72 into forced contact with first strand member 500 thereby crimping the strand between recesses 75 and anvils 76 to reduce the bending strength. Once crimping is completed,

iluid cylinders

73 and 74 are energized to open and fluid cylinder 106 is energized to retract thereby lowering hinged gauge 104. First strand 500 is then fed further into the apparatus until the leading end of strand 500 passes over die 226 and the crimped area from crimping means 60 is resting on die 56. The leading end of strand 500 will be three to live inches to the left of die 226.

Fluid cylinders

73 and 74 of crimping

means

58 and 60 are again energized to bring conditioning dies 70 and 72 into forced contact with strand 5,00 as hereinabove described. Fluid cylinder 234 of retaining means 228 is actuated to direct clamp 232 against first strand 500, thereby bending first strand 500 over die 226 and holding it in a fixed position with respect thereto.

Fluid cylinder 116 is then energized to being the forming and stretching operation. Fluid cylinder 116 drives die 126 into strand member 500 to deform it downward. The force of the downward thrust of die 126 against strand member 500 acts as a pulling force to pull carriage 2 towards the left, or towards first support and clamping means C, while at the same time forcing carriage 110 of power forming means B to the left, or towards first support and clamping means C. The leftward movement of carriage 2 and carriage 11() continue as cylinder 116 travels through its stroke. Somewhere between one-eighth and one-half inch before

adjustment nuts

136 and 138 stop the downward movement of cylinder 116, carriage 2 leftward travel is stopped as

adjustment bolts

38 and 40 contact stop blocks 30 and 32. Upon to this point first strand member 500 has only received a forming action due to the initial set-up of the apparatus. Through the final oneeighth to one-half inch of die 126 travel, elastic deformation is converted to plastic deformation by a stretching action such that a V-shaped configuration is permanently formed from first strand member S in Contact at its apex with secoind strand member 600.

Fluid cylinder 324 of each joining means 299 is then actuated to drive its respective welding gun 336 mounted on carriage 320 into proximity with the apex and second strand contact. Each gun 336 is then actuated to perform the actual joining operation. Simultaneously therewith,

fiuid cylinders

73 and 74 of crimping

means

58 and 60 are energized to extend in order to separate dies 70 and 72. When

cylinders

73 and 74 have been actuated and opened, fluid cylinder 116 is actuated to retract and thereby raise die 126. Fluid cylinder 46 is then actuated to extend so rod end 48, acting against tab 5,0, forces carriage 2 to the right, or away from first support and clamping means C, until

adjustment bolts

18 and 20 contact stop blocks and 32 at the home position. Similarly therewith, when die 126 has been fully retracted, fiuid cylinder 146 is energized so that rod end 147 engages carriage 110 to force ot to the right, or away from first support and clamping means C, to its home position as determined by adjustment bolt 142.

Following joining, each welding gun 336 is retracted and cylinder 324 of each joining assembly 299 is energized in the opposite direction to withdraw their respective carriage 320 and welding gun 336 from the proximity of the joining operation.

Advancement of the partially completed semi-joist, comprised of first strand 500 and second strand 600, is then accomplished solely through the use of first support and clamping means C. Fluid cylinder 362 of disappearing gauge 358 is retracted to lower hinged gauge 360 below the supporting plane formed by rollers 350. Fluid cylinder 210 is energized to move carriage 200, indirectly containing die 226 and clamp assembly 228, to the left to thereby index the partially completed semi-joist one work station due to the preselected stroke length of cylinder 210.

Fluid cylinders

73 and 74 of crimping

means

58 and 60 are again energized to the closed position to retain and crimp a new section of first strand member 500. Simultaneously, fiuid cylinder 234 of retaining assembly 228 is actuated to close in order to remove clamp 232 from its position against die 226 and release first strand member 500 from its fixed position with respect to die 226. Fluid cylinder 250 is energized to the closed position to move carriage 220 with retaining assembly 228 and die 226 mounted directly thereon, from contact with first strand member 500.

Fluid cylinder 210 is then energized to closed position which moves carriage 200 to its longitudinal home position against permanently mounted stop 266. Fluid cylinder 25() is next energized to the open position to move carriage 220 with clamp assembly 228 and die 226 to the tranverse home position such that die 226 again supports first strand 500. Again, this is possible because of the predetermined stroke of fluid cylinder 218. Fluid cylinder 234 of retaining assembly 228 is again energized to the extended position to retain first strand member 500 in a fixed position with respect to die 226.

At this stage, the apparatus is again in operative condition to form another V-shaped configuration to become part of the semijoist. The crimped portions of strand 500, formed in crimping

means

58 and 60 on the previous stroke of the apparatus, are now located directly below die 126 and above die 56. As the semijoist is manufactured, it is indexed to semijoist output table F from where it may be taken and conveniently stored. The abovedescribed operation is repeated as desired for the particular length of semijoist required.

The second embodiment of the bending strength reducing feature for first strand member 500 is depicted in FIG. l and FIG. 8. Induction heating means 86 and 88, each containing

induction heating elements

94 and 96, replace crimping

means

58 and 60 and are located with respect to die 56 in the same manner as hereinabove disclosed. In loading the apparatus, first strand member 500 passes through the loops of

induction heating elements

94 or 96 of

means

86 and 88 while the remainder of the loading process remains the same as disclosed above. Retaining means 84 is necessarily required here in order to maintain first strand member 500 in a fixed relationship with the apparatus. As best shown in FIG. 3, retaining means 84 operates by energizing fluid cylinder 102 to the closed position thereby bringing hinged upper clamping means into proximity with lower clamping means 98 to apply a retaining force to first strand member `500. Fluid cylinder 102 is actuated simultaneously with ifiuid cylinder 234 of retaining means 228 in first support and clamping means C. Induction heating by

induction heaters

94 and 96 begins as die 126 starts its downward movement and continues until first support and clamping means C has been fully indexed. Retaining means 84 is set to release the retaining force on first strand member S00 as die 126 is retracted from its downward position, similar to the release of work preparation means `518 and 60 described above. Fluid cylinder 102 of retaining means 84 is reactuated to again clamp the first strand member 500 in a stationary position with respect to die 56 when fiuid cylinder `210 of first support and clamping means C has been actuated to the forward position to index the partially completed semijoist.

Once a semijoist has been completed, a second straight strand member may be added by any conventional means in order to form a completed structural joist.

Although the invention has been described with reference to specific embodiments, variations thereto within the scope of the claims will be apparent to those skilled in the art.

Having thus described our invention, we claim:

1. An apparatus for producing a structural element from rst and second elongated strand members, said apparatus comprising:

first and second support means for supporting said strand member, said second support means being movable towards said first means; said first means being located at an initial position,

said first strand member extending along the longitudinal axis, said first means being restrained from movement toward said second means beyond a selected point; said second means being movable to a second position spaced from said initial position generally along said axis, said second means having a predetermined allowable travel along said axis, defined by the distance between said initial and said second positions;

locking means for locking said first strand member with respect to each of said first and second support means;

power means for forming said first strand member into a generally V-shaped configuration with an apex at a predetermined position with respect to said first and second means by bending said first strand member at three spaced areas on said first strand member, said power means including a forming element having a predetermined allowable travel generally normal to said axis while in contact with said first elongated strand member, whereby one of said rst or second means is drawn toward the other by said first strand member for a predetermined distance generally along said axis;

strand support means for adjustably supporting said second strand member in a longitudinally coextensive relationship with said first strand member and adjacent said predetermined position; and,

means for joining said first and second elongated strand members at said predetermined position when said forming element has operated said predetermined distance while in contact with said first elongated strand member.

2. An apparatus as defined in claim 1 including first means for lessening the bending strength of said first strand member at least one of said spaced areas prior to forming by said power means.

3. An apparatus as defined in claim 2 incl-udin g a second means for lessening the bending strength of said first strand member at another of said spaced areas, said another spaced area being the next adjacent area to said at least one spaced area.

`4. An apparatus as defined in claim 3 wherein said first and second means for lessening the bending strength are devices for crimping said first strand member.

S. An apparatus as defined in claim 3` wherein said first and second means for lessening the bending strength are induction heating inductors with central passageways, means for locating said another and said at least one area within said passageways and means for energizing said inductors.

6. An apparatus as defined in claim 2 wherein said first means for lessening the bending strength is a device for crimping said first strand.

7. An apparatus as defined in claim 6 wherein said crimping device includes two spaced anvils having an opened feeding position and a closed crimping position, means for moving said first strand member between said anvils when in said feeding position, and power means for forcing said anvils into said closed position for crimping said first strand member at said at least one area.

8. An apparatus as defined in claim 7 wherein said device further includes means for maintaining said first strand member spaced from lboth of said anvils while said anvils are in said opened position.

9. An apparatus as defined in claim 2 wherein said first means for lessening the bending strength is an induction heating inductor with a central passageway, means for locating said at least one area within said passageways and means for energizing said inductor.

10. An apparatus as defined in claim 1 wherein said power means includes means for allowing movement of said power means coextensive with the longitudinal axis of said second strand member d-uring its forming operation.

11. An apparatus as defined in claim 10 wherein said movement allowing means includes fixed guide means eX- tending generally parallel to said second strand member and guide means in said power means for reciprocally supporting said power means on said fixed guide means.

12. An apparatus for producing a structural element from first and second elongated strand members, said apparatus comprising:

first and second support means for supporting said first strand member, said second support means being movable toward said first means;

said first means being located at an initial position, said 10 first strand member extending along a longitudial axis; said second means being movable to a second position spaced from said initial position generally along said axis, said second means having an allowable travel along said axis, defined by the distance between said initial and second positions; locking means for locking said first strand member with respect to each of said first and second support means;

power means for forming said first strand member into a generally V-shaped configuration with an apex at a predetermined position with respect to said first and second means by bending said first strand member at three spaced areas on said first strand member, said power means including a forming element having a predetermined allowable travel generally normal to said axis while in contact with said first elongated strand member, whereby at least one of said first or second means is drawn toward the other by said first strand member for a predetermined distance generally along said axis;

13. An apparatus as dened in claim 12 wherein said first and second support means have means for engaging said first strand member at spaced apart bending areas, prior to forming said first strand member, said engaging means and, thus said bending areas being spaced apart a distance less than the total length of said V-shaped configuration after forming said first strand member whereby said first strand member is stretched while being formed by said power means.

14. An apparatus for producing a structural element from first and second elongated strand members, said apparatus comprising:

said first means being located at an initial position, said first strand member extending along a longitudinal axis; said second means being movable to a second position spaced from said initial position generally along said axis, said second means having an allowable travel along said axis, defined by the distance between said initial and second positions; locking means for locking said first strand member with respect to each of said first and second support means;

power means for forming said first strand member into a generally V-shaped configuration with an apex at a predetermined position with respect to said first and second means by bending said first strand member at three spaced areas on said first strand member, said power means including a forming element having a predetermined allowable travel generally normal to said axis while in contact with said first elongated strand member, whereby at least one of said first or second means is drawn toward the other by said first strand member for a predetermined distance generally along said axis; and,

means for advancing said V-shaped configuration along said axis after said V-shaped configuration is formed.

15. An apparatus as defined in claim 14 wherein said advancing means includes first fluid means for pulling said first support means along said axis away from said first support means initial position and second fluid means for retracting said first support means transverse to said axis and out of engagement with said first strand member.

l l 16. A method for producing a structural element from first and second elongated strand members comprising the steps of:

fixedly positioning said first strand member across movable first and second support means; positioning said second strand member on a strand support means in a longitudinally coextensive relationship with said first strand member; power forming said first strand member into a generally V-shaped configuration by applying a force generally normal to said first strand member longitudinal axis between said first and second support means through a predetermined distance; advancing said first strand member a predetermined distance coextensive with said first strand longitudinal axis by moving said first support means through a predetermined distance; disengaging said first strand member by moving said first support means transverse to said longitudinal movement; reversing the longitudinal movement of said first support means; and, reversing said transverse movement of said first support means. 17. A method for producing structural element comprising the steps of:

clamping a first elongated member at two predetermined end points, longitudinally parallel to a second elongated member; applying a bending force to said first member generally between said end points to drive said first member l2 to contact said second member to form a longitudinally undulating element with an apex, formed between said end points;

allowing at least one of said end points and said bending force to move longtudinally coextensive to said second member;

joining said undulating member and said second member at their point of contact;

repeating said clamping, bending, and joining steps as required.

18. A method as defined in claim 17, which further includes the step of stretching said first member during bending.

19. A method as defined in claim 17, which further includes the step of reducing the bending strength of said first member generally at said end points.

20. A method as dened in claim 17 which further includes the step of reducing the bending strength of said first member generally at said end points and at the point of application of said bending force.

References Cited UNITED STATES PATENTS THOMAS H. EAGER, Primary Examiner U.S. Cl. X.R. 29-200 B