Method and apparatus for making steel joists

The present invention provides a method and apparatus for making joists. The chord members of the joists consist of two pairs of spaced apart angle irons, and the web portion of the joists consist of a plurality of linear metal bar lengths. Under a computerized control, the pairs of angle irons are spaced from one another by a predetermined distance depending on the design characteristics of the joist to be made, and the metal bar lengths are individually selected and cut to provide a metal bar having a specified diameter and a specified length, after which each of the metal bars is selectively positioned, in sequence, between the two pairs of angle irons, and then each end of each metal bar is automatically welded to the angle irons in a predetermined sequence.

BACKGROUND OF THE INVENTION 
For many years, joists have been a fundamental component of the 
construction industry, and they have a wide variety of forms depending on 
their particular load bearing application, such as supporting floor and 
roof systems. 
In its most common form, a joist consists generally of two longitudinally 
extending chord members spaced from one another and interconnected by a 
web that extends between the chord members. In joists of this type which 
are intended for use over short spaces (e.g., up to sixty feet), the web 
of the joists is most frequently formed of a plurality of lengths of round 
steel bars which are bent into a predetermined serpentine or sinuous 
shape, and each such length is then welded to the top and bottom chord 
members at the several points where the apexes of the upper and lower 
curved portions of the web abut the top and bottom chord members. Again, 
in their most common form, each of the top and bottom chord members are 
formed of two spaced angle irons and the apexes of the curved portions of 
the sinuous web pieces are positioned between the spaced, flat wall 
portions of each pair of angle irons and welded thereto by one of several 
well-known welding techniques, usually gas shielded or flux cored welding. 
Short span joists of this type are usually made by what is essentially a 
manual welding operation because the use of lengths of curved web pieces 
in the joists does not lend itself to more fully automated welding 
procedures. More specifically, the web piece is typically between four and 
six feet in length, and its sinuous curvature is such that the desired 
spacing between adjacent apexes is typically twenty-four inches, whereby 
it must be welded to the top chord member at a position along its length 
spaced every twenty-four inches, and the same welding must also be done at 
the same spacing along the bottom chord member. However, because of the 
inherent "spring back" in the sinuous curvature of the steel web pieces, 
the desired twenty-four inch spacing is not obtained on a consistently 
exact basis. This variation is acceptable in joists and is readily 
accommodated in a manual welding operation where the welding technician 
can position the welding equipment at whatever point the apex of the web 
piece abuts the chord members. However, in automatic welding operations, 
the welding equipment is generally fixed in position, and the significant 
variations caused by the aforesaid "spring back" can result in an 
automatic weld being made at a point where there is little or no abutment 
between web piece and the chord member. 
The most common manual joist making machine operation for short span joists 
consists of using a jig for the chord member to properly locate the two 
pairs of angle irons in spaced relation to one another, and all of the 
sinuous lengths of the web material are individually laid into the jig 
manually so that the apexes of the web pieces are disposed between the top 
and bottom angle irons, and clamps are used to hold the web pieces to the 
angle irons at each point of abutment. In some of these joists the end 
portion may also be formed of one or two linear round metal bars which are 
also manually placed between the chord members at both ends thereof, 
adjacent the sinuous web portions and then clamped in place thereat. The 
assembled joist is then removed from the jig and taken from the assembly 
area to a welding area where welds are made at each point of abutment. In 
most long span joists, a similar manual forming operation is used, but the 
web may be made up of a plurality of linear lengths of angle iron which 
have both end portions crimped to reduce their width so that they will fit 
within the spacing (e.g., one inch) between the angle irons of the two 
chord members before they are manually welded to the angle irons. 
In the past, it is also known that joists could be manually formed using 
two spaced pieces of wood as the chord members, and using a plurality of 
individual metal tubes as the webbing, these metal tubes having their end 
flattened and being arranged in an alternating "V" and inverted "V" 
pattern with the one flattened end of each adjacent tube overlapping that 
of an adjacent tube and being fixed to the wooden chord member by 
connecting rods inserted through the chord member and the overlapping end 
portion. 
Forming joists by what is essentially a manual welding operation is time 
consuming and, more importantly perhaps, requires significant labor costs, 
particularly as to the costs of skilled welding technicians. Another 
disadvantage that can result from the use of sinuous lengths of web 
material in manual operations is that excess material, and therefore 
increased costs, is utilized even though it is not needed. In some joist 
designs, strength requirements dictate that the compression member in the 
web must be larger than the tension member, so when a sinuous web piece is 
used the steel bar stock from which it is made must be of a sufficient 
size to meet the strength requirements of the compression member portion, 
and since the web piece is made of a continuous piece of the steel bar 
stock having a constant diameter along its length, the tension member 
portion of the web piece is of a size greater than that required for its 
load bearing function. 
The present invention provides a method and apparatus for automatically 
making a joist which overcomes the aforesaid drawbacks of known technology 
for making joists, and which provides a number of practical and commercial 
advantages. 
SUMMARY OF THE INVENTION 
The present invention is directed to a method and apparatus for making 
steel joists which consist of two spaced chord members interconnected by 
metal bars forming a web therebetween, such method and apparatus including 
an arrangement for delivering a plurality of substantially linear metal 
bars of predetermined lengths to an assembly station, and also delivering 
two substantially linear chord members of predetermined lengths to such 
assembly station, the chord member delivery arrangement also being 
utilized for positioning the chord members in spaced relation to one 
another at the assembly station. An arrangement is also provided for 
grasping and manipulating the metal bars in a predetermined sequence so 
that one metal bar at a time is located between the spaced chord members 
with each end of each metal bar being disposed in abutting relationship 
with a different one of the chord members, and the ends of each such metal 
bar are welded automatically to the chord members at the point of abutment 
therebetween. 
In the preferred embodiment of the present invention, each of the chord 
members consists of a pair of angle irons which are positioned at the 
assembly station so that one corresponding flat wall portion of each angle 
iron in each pair is arranged in spaced parallel relation to the 
corresponding flat wall portion of the other angle iron in that pair, and 
the metal bars are manipulated so that each end thereof is disposed 
between the spaced wall portions of the angle irons in each pair for 
subsequent welding thereat. Also, the metal bars are manipulated in a 
predetermined sequence so that one metal bar which is positioned between 
the aforesaid spaced wall portions of the pairs of angle irons is welded 
to only one angle iron in each such pair, then the next metal bar is 
positioned between the pairs of angle irons, and, then, the first metal 
bar is welded to the other two angle irons in each said pair to complete 
the weld for that metal bar. 
Also, in the preferred embodiment of the present invention, an arrangement 
is provided for automatically forming the metal bars into their 
predetermined lengths by advancing a stock piece of metal bar beyond a 
fixed reference point for a distance corresponding to the predetermined 
length of a particular metal bar, and then cutting the stock piece at the 
reference point. Additionally, this arrangement preferably includes a 
plurality of forming stations with each station having its own feeder and 
cutter, and each station feeds and cuts a stock piece having a different 
diameter. 
The angle irons in each pair are preferably engaged separately, and are 
selectively movable toward and away from one another between a first 
position at which the spacing therebetween is greater than the diameter of 
the metal bar to be positioned therebetween, and a second position at 
which the angle irons are moved toward one another to press the flat wall 
portions thereof into firm abutment with the ends of the metal bar for 
subsequent welding thereto. 
The arrangement for grasping and manipulating the metal bars preferably 
includes a device that is rotatable about an axis of rotation generally 
perpendicular to the plane containing the two chord members, and this 
device is provided with arms for releasably grasping the metal bars and is 
rotatable to selectively position the grasped metal bars at any one of a 
plurality of different angular relationships with respect to the chord 
members, whereby each metal bar can be located between the chord members 
at any given angle that is required for the design of the particular joist 
being made. Also, the arms are preferably spaced from one another to grasp 
the metal bar at spaced locations, and the arms are selectively movable 
toward and away from one another to permit the arms to properly hold metal 
bars of different lengths. 
The arrangement for welding the metal bars to the chord members preferably 
includes a welding tip which is mounted on a mounting arrangement movable 
toward and away from the ends of the metal bars when they are disposed 
between the chord members to permit the welding tip to be selectively 
moved to a position for engaging the end of the metal bar to form the weld 
thereat, and this arrangement also preferably includes a position sensor 
mounted on the aforesaid mounting means for movement therewith, the sensor 
being movable with respect to the mounting arrangement toward and away 
from the ends of the metal bar for generating a signal which is a function 
of the relative positions between the end of the metal bar and the 
mounting arrangement.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Looking now in greater detail at the accompanying drawings, FIG. 1 is a 
perspective view illustrating the preferred embodiment of the apparatus 
for forming steel joists in accordance with the present invention, some of 
the details of the various components of the apparatus being omitted for 
clarity of overall illustration of the apparatus. The apparatus consists 
of a number of different operations which take place in a predetermined 
sequence, each of these operations being generally formed at different 
stations as described in greater detail below and which may be generally 
characterized as a metal bar cutting station 10, a metal bar transfer 
station 12, a metal bar and chord member advancing station 14, and an 
assembly station 16 which includes welding apparatus 18 and an arrangement 
20 for grasping and manipulating metal bars at the assembly station 16. A 
roller-type conveyor 22 is also provided for transporting finished joists 
24 away from the apparatus, and a control panel 26 which is 
diagrammatically illustrated in FIG. 1 is electrically connected to all of 
the various operating components of the apparatus by suitable electrical 
wires (not shown). The control panel 26 includes a conventional central 
processing unit (CPU) which may be of any conventional type that can be 
programmed to control the various operations of the apparatus in a 
predetermined and programmable sequence, such as an IBM AT computer sold 
by International Business Machines Corporation in Armonk, N.Y. 
The apparatus at the cutting station 10 is shown in greater detail in FIGS. 
2 and 3. The apparatus is generally shown in FIG. 2 to include a plurality 
of locations at which individual metal bars 28 are cut to length, and the 
particular arrangement shown in FIG. 2 provides for cutting sixteen metal 
bar stocks 28 but a different number of cutters could be provided, if 
desired. Each of the sixteen different metal bar stocks 28 will generally 
be round bars, each having a different diameter, and each metal bar stock 
28 is located adjacent a different opening 30 in the cutting block 32 
which is moved laterally in a housing 34 by a hydraulic cylinder 36 
operating through a connecting shaft 38. To assist in forming a clean cut 
of the metal bars 28, a support plate 29 is provided adjacent each opening 
30 in the cutting block 32 (only one support plate 29 being shown in FIGS. 
1 and 2), each support plate 29 acting to support the portion of the metal 
bar 28 immediately adjacent the opening 30 during shearing movement of the 
cutting block 32 whereby such shearing movement does not cause any 
significant bending or distortion of the metal bar 28. 
In FIG. 3, only one of the advancing and cutting arrangements is shown, but 
it will be understood that an identical arrangement is provided at each of 
the sixteen openings in the cutting block 32. A motor 40 rotates a common 
drive shaft 42 that extends horizontally behind the housing 34, and at 
each of the openings 30 a drive wheel 44 is rotatably carried on the drive 
shaft 42 so that it is disposed directly beneath a pressure roller 46 
rotatably mounted in an inverted U-shaped bracket 48 that is connected to 
the piston rod 50 extending from an air cylinder 52 having inlet and 
outlet conduits 54, 56, the air cylinder 52 operating in the conventional 
manner to raise and lower the housing 48 and the pressure roller 46 under 
the control of the CPU as described below. The air cylinder 52 is mounted 
in a housing subassembly 58 which is formed with a passageway 60 that 
extends horizontally in a direction towards each of the openings 30 so 
that one of the metal bar stocks 28 can extend therethrough, between the 
drive wheel 44 and the pressure roller 46. The housing subassembly 58 may 
also include two side rollers 62, only one of which is shown in FIG. 3, 
for engaging the sides of the metal bar stock 28 when it is inserted in 
the passageway 60 to provide guidance and support for the metal bar stock 
28 as it moves through the passageway 60. A pair of opposed and 
conventional sensors 64, which may be of any well known type, are mounted 
on the housing subassembly 58 at the front end of the passageway 60, and 
an identical pair of opposed sensors are mounted on the housing 
subassembly 58 at the rear end of the passageway 60, the sensors 64 and 66 
each generating a signal which is transferred to the CPU each time the end 
of the metal bar stock 28 breaks the plane of the beam extending between 
the respective pairs of sensors 64, 66. 
The operation of the above-described cutting station is as follows. At each 
of the openings 30, a metal bar stock having a different diameter is 
manually inserted into the passageway 60 so that it extends between the 
drive wheel 44 and the pressure roller 56 (which is located at its raised 
position by the air cylinder 52), and between the side rollers 62, with 
the front end of the metal bar stock 28 disposed just beyond the innermost 
sensors 66. The interruption of the beam between the sensors 64 and 66 by 
the metal bar stock 28 sends a signal to the control panel 26 to indicate 
that a length of metal bar stock 28 is in place, and, as indicated above, 
the CPU in the control panel 26 is programmed to determined which of the 
sixteen different metal bar stocks 28 is to be cut, and the particular 
length which the cut piece is to have, both of which will depend on the 
design of the particular joist being made. The control panel 26 then sends 
an appropriate signal to the desired station at which the correct size of 
metal bar stock 28 is located, and the air cylinder 52 is operated to 
lower the pressure roller 56 into contact with the top surface of the 
metal bar stock 28 so that it is firmly held between the pressure roller 
46 and the drive wheel 44, and the motor 40 is operated, initially, to 
turn the shaft 42 and the drive wheel 44 in a reverse direction so that 
the metal bar stock 28 is withdrawn through the passageway 60 until the 
leading end of the metal bar stock 28 no longer breaks the beam of the 
innermost sensor 66, whereupon the motor 40 stops so that the lead end of 
the metal bar stock 28 is then located essentially at the plane of the 
beam of the sensor 66 which provides a reference point that is fixed with 
relation to the cutting block 32. The motor 40 is then operated in a 
reverse direction and the drive wheel 44 advances the metal bar stock 
through the passageway 60 and through the adjacent opening 30 in the 
cutting block 32 so that the metal bar stock 28 is advanced outwardly from 
the aforesaid reference point and the cutting block 32 by the motor 40 for 
a predetermined distance, depending on the particular length of the metal 
bar stock 28 to be cut, at which point the motor 40 stops to stop the 
further advance of the metal bar stock and leave it extending outwardly 
from the cutting block 32 as shown in FIG. 2. At this point, the control 
panel 26 operates the hydraulic cylinder 36 to move the cutting block 
laterally with respect to the housing 34 to create a shearing force that 
severs the metal bar stock 28 at the cutting edge between the housing 34 
and the movable cutting block 32, whereupon the movable cutting block 32 
is then returned to its initial position by the hydraulic cylinder 36. 
As illustrated in FIG. 1, the transfer station 12 includes an extension 68 
for supporting a horizontally extending track member 70 which supports a 
vertically extending carriage 72 for lateral movement therealong by a 
motor 79, the carriage 72 having mounted thereon vertically extending 
tracks 73. A vertical member 74 is mounted on the tracks 73 by a mounting 
plate 75 slidable therealong, and an air cylinder 78 is carried on the 
vertical member 74 and has a piston 81 that is fixed at its upper end to a 
plate 77 fixed to the upper end of the carriage 72. The lower end of the 
vertical member 74 has mounted thereto an air cylinder 81 that is arranged 
to support thereon a clamp 80 so that the clamp 80 can be moved 
horizontally back and forth by the air cylinder 81. 
In operation, the air cylinders 78 and the motor 79 are operated by the 
control panel 26 to move the vertical member 74 and the carriage 72 to 
position the clamp 80 directly in front of the opening 32 through which 
the metal bar stock 28 to be cut extends so that the end of the metal bar 
stock 28 is advanced into the clamp 80. After the metal bar stock is cut 
to length at the cutting station as described above, the air cylinder 81 
is operated to move the clamp 80 away from the cutting station 10 to 
extract the cut metal bar 28 therefrom, and then the drives for the 
carriage 72 and the vertical member 74 are operated by the control panel 
26 to first raise the clamped metal bar 28, and to then move the metal bar 
horizontally to a position above the hopper 82 where the clamp 80 is 
operated to release the metal bar stock and drop it into the hopper 82, 
whereupon the clamp 80 is returned by the carriage 72 and the vertical 
member 74 to a position for receiving the end of the next metal bar stock 
28 to be cut. 
As best seen in the diagrammatic illustrations in FIGS. 4 and 6, the hopper 
82 is formed with inwardly diverging side walls 84 that terminate in two 
corresponding vertical wall portions 86 that are spaced from one another 
to provide a narrow slot 88 so that when a metal bar 28 is dropped into 
the hopper 82 it will be guided by the diverging side walls 84 to the slot 
88 and be positioned at the bottom thereof as shown in FIG. 6. The 
vertical walls 86 are bent inwardly at the bottom edge thereof to hold the 
metal bar 28 and to also leave a horizontally extending opening 90 beneath 
the metal bar 28, and this opening 90 receives therein the upper end of a 
vertically disposed advancing finger 92 that is mounted by opposed rollers 
94 on a horizontally extending track element 96, and which includes a 
mounting block 98 carried along the track 96 with the advancing finger 92, 
the mounting block 98 having a motor 100 carried thereon which is 
connected through a drive shaft 102 to a drive gear 104 that engages a 
gear rack 106 as best seen in FIG. 6. 
In operation, after a metal bar 28 has been cut to length and dropped in 
the hopper 82, it is positioned at the bottom of the slot 88, and the 
upwardly extending advancing finger 92 is positioned to engage the rear 
end of the metal bar 28 as shown in FIG. 6, the engaging portion of the 
advancing finger 92 preferably being slightly magnetized to provide a 
firm, but releasable, engagement between the advancing finger 92 and the 
metal rod 28. When it is desired to advance the metal bar 28 to the 
assembly station 16, the motor 100 is operated by the control panel 26 to 
move the advancing finger 92 horizontally along the track 96 so that the 
advancing finger 92 pushes the metal rod 28 out of the forward end of the 
hopper slot 88, and when the advancing finger 92 stops, the aforesaid 
slight magnetism will cause the metal rod 28 to stop also rather than to 
continue moving under its own inertia. 
As illustrated in FIG. 1, an inventory of angle irons 108 are maintained in 
a storage area behind the advancing station 14, and, as best seen in FIG. 
4, four of these angle irons 108 are positioned at the advancing station 
14 in two pairs, each pair having an upper angle iron 108' and a lower 
angle iron 108" which together will form a chord member of the finished 
joist. It will also be noted that the angle irons 108' and 108" in each 
pair are positioned so that the adjacent flanges of the two angle irons 
are disposed in spaced parallel relationship to one another for ultimately 
receiving therebetween the ends of a metal bar 28 in a manner to be 
described presently. 
The four angle irons are manually fed into the advancing station 14, and 
the mechanical arrangement for advancing and supporting the upper angle 
iron 108' in each pair is identical, as is the mechanical arrangement for 
advancing and supporting the lower angle iron 108" in each pair. As best 
seen in FIG. 4, the upper angle iron 108' in each pair is initially 
supported at its lower horizontal flange by a plurality of spaced and 
horizontally extending rods 110 and the upper vertical flange is disposed 
between a vertical plate 112 and an overhanging flange member 114. The 
rods 110 are fixed to a mounting plate 116 that is moved horizontally by 
an air cylinder 118 acting through a connecting shaft 120 so that the 
extending ends of the rods 110 can be selectively moved between a first 
position at which they are located between the horizontal flanges of the 
upper angle iron 108' and the lower angle iron 108" for supporting the 
upper angle iron 108' as shown in FIG. 4, and a second position at which 
the rod members are withdrawn outwardly from between the angle irons 108', 
108" after the upper angle iron 108' has been advanced sufficiently to be 
supported at the assembly station 16 in a manner to be described 
presently, this second position of the rods 110 permitting relative 
vertical movement of the upper angle iron 108' with respect to the lower 
angle iron 108" for a purpose that will also be described presently. As 
indicated above, each of the two upper angle irons 108' is advanced 
manually along the upper surface of the rods 110 until the forward end of 
the angle iron 108' passes between a knurled drive member 122 and a 
pressure roller 124 and the forward end of the upper angle iron 108' 
strikes a limit switch 126 which signals that the upper angle iron 108 is 
properly positioned to be advanced horizontally by rotating the drive 
member 122 which is driven by its own motor 128 (see FIG. 5) through a 
drive shaft 130. 
The lower angle iron 108" in each pair is manually fed into the advancing 
station by positioning the horizontal flange of the angle iron 108" on a 
plurality of idler rollers 132 mounted in the vertical side wall 112 as 
illustrated in FIG. 4. The two lower angle irons 108" are advanced 
manually along these idler rollers 132 until they reach a knurled drive 
wheel 134 (see FIG. 5) which is identical in construction and function as 
the drive wheel 122 (with its pressure roller 124 and limit switch 126) as 
described above, and the second knurled drive member 134 is driven by its 
own motor 136 (see FIG. 5). Thus, in the same manner as that described 
above, the lower angle irons 108" are manually advanced along the idler 
rollers 132 until they strike a limit switch identical to limit switch 
126, after which each of the lower angle irons 108" is driven by its own 
knurled drive member 134 and motor 136. 
Therefore, it will be understood that each of the two upper angle irons 
108' can be advanced automatically for any desired distance by operating 
the motor 128 and drive member 122 associated with each of the upper angle 
irons 108', and, similarly, the lower angle irons 108" can be selectively 
advanced any desired distance by operating the motors 136 and drive 
members 134 for a predetermined period of time. 
FIG. 9 illustrates, in greater detail, the mechanism by which each of the 
pressure rollers 124 are employed to urge the flanges of the angle irons 
into contact with their respective drive members. More specifically, FIG. 
9 illustrates one of the drive members 134 for one of the lower angle 
irons 108", and it will be noted that the vertical flange of such angle 
iron is disposed between the drive member 134 and the pressure roller 124, 
and the pressure roller 124 is carried on a pivot arm 138 pivoted about a 
pivot shaft 140 and having its other end attached to the reciprocating 
piston rod 142 of an air cylinder 144. When the end of an angle iron 
engages its associated limit switch 126 (see FIG. 4), the limit switch 
generates a signal which operates the air cylinder 144 to extend the 
piston rod 142 and thereby cause pivot arm 138 to firmly press the flange 
of the angle iron against the knurled surface of the drive member 134. 
Moreover, when the angle iron has been advanced during the joist making 
operation to such an extent that the trailing end of the angle iron clears 
its associated limit switch 126, the air cylinder 144 is operated in a 
reverse direction to move the pivot arm 138 and its attached pressure 
roller 124 away from the drive member 134 so that a new angle iron can be 
received therebetween. 
In FIG. 1, some of the details of the construction of the assembly station 
16 which are shown in other figures have been deleted in FIG. 1 so as to 
more clearly illustrate the relative position of the two horizontally 
extending angle iron supports 146 and 148 which are utilized to support 
the horizontal flanges of the two bottom angle irons 108". The left hand 
(as viewed in FIG. 1) horizontal support member 146 is mounted in fixed 
relation to the frame 150 of the assembly station 16, and the other 
horizontal support 148 is mounted on a vertical wall 152 carried on a 
platform 154 that is movable along guide rails 156 (one of which is 
visible in FIG. 1), and a drive motor 158 operates a drive gear 160 that 
engages a rack 162 disposed at the underside of the platform 154 whereby 
operation of the motor 158 will cause the entire platform, including the 
horizontal support 148, to move away from and toward the fixed horizontal 
support 146. Since the apparatus of the present invention is designed to 
make joists of a variety of different sizes, the selectively movable 
platform 154 permits the two horizontal supports 146 and 148 to be 
adjustably spaced from one another so that they can support the two pairs 
of angle irons at any desired spacing that is required for the design of a 
particular joist that is being made. 
The horizontal supports 146 and 148 are shown in greater detail in FIG. 5, 
and the direction arrow 164 indicates the above-described movement of the 
movable horizontal support 148 toward and away from the fixed horizontal 
support 146. The horizontal supports 146, 148 each include a horizontal 
surface across which the horizontal flanges of the two lower angle irons 
108" slide when they are advanced by their respective drive members 134 as 
described above. An outwardly extending flange 168 is positioned above 
each of the horizontal support surfaces 146 and 148 to slidably support 
the horizontal flanges of the upper angle irons 108', one of these flanges 
being visible in FIG. 5 and it being understood that an identical flange 
is positioned above the horizontal surface of the movable horizontal 
support 148. The vertical walls 170 from which the horizontal support 
flanges 168 extend are both fixed to the beam 316. 
A block 174 is vertically mountable on two vertically extending guide 
shafts 176 by a motor 178 through a conventional cam and follower 
arrangement (not shown), and it will also be noted that the movable block 
174 is fixed to an L-shaped support member 180 on which is mounted the 
upper angle iron drive member 122 and its motor 128. Accordingly, when the 
block 174 is moved vertically upwardly or downwardly by the motor 178, the 
entire assembly for advancing the upper angle iron 108' moves together as 
an integral unit, and the upper angle iron 108' is therefore moved 
relative to the adjacent lower angle iron 108" by the flange portion 122' 
of the drive member 122 to increase and decrease the spacing therebetween 
for a purpose to be described presently. Additionally, a clamping finger 
172 is arranged to be moved vertically (see direction arrow 182) by an air 
cylinder (not shown) for urging the upper angle iron 108' upwardly against 
the block 175 away from the lower angle iron 108" so that the ends of a 
metal bar 28 may be easily disposed therebetween as will be described 
presently, and a second clamping finger 177 is arranged to be moved 
vertically by an air cylinder (not shown) for urging the lower angle iron 
108" downwardly into firm contact with the supports 146, 148 to assist in 
separating the upper and lower angle irons 108', 108". 
As illustrated in FIGS. 4 and 6, the above described hopper 82 is disposed 
between the two pairs of upper and lower angle irons 108', 108", and when 
the metal bar 28 in the slot 88 is advanced forwardly by the moveable 
finger 92 as described above, the metal bar is moved into a position at 
which it is cradled by two identical grasping heads 184 which are shown 
diagrammatically in FIG. 6, and which are part of the manipulating and 
grasping equipment 20 that is shown in more detail in FIGS. 1 and 7, each 
of the grasping heads 184 being formed with a V-shaped cradle portion 186 
in which the metal bar 28 rests and a selectively moveable clamping pin 
188 that is moved vertically by an air cylinder 190 between a raised 
position which permits the metal bar 28 to be slidably received in the 
cradle portions 186 and a lowered position in which it presses against the 
upper surface of the metal bar 28 and holds it securely in place in the 
cradle portions 186, the vertical movement of the pins 88 being indicated 
by the direction arrow 192 in FIG. 7. 
As best seen in FIGS. 1 and 7, the aforesaid frame 150 includes a 
superstructure 194 on which the manipulating and grasping equipment is 
carried, and the two grasping heads 184 are each mounted on a vertical 
plate 196 that is slidably carried on the tracks 198 of a horizontal plate 
200. The vertical plates 196 are moveable toward and away from one another 
along the tracks 198 as indicated by the direction arrows 202 and 204 by a 
rack and pinion drive 206 that is operated by a motor 208, this selective 
movement of the grasping heads 184 toward and away from one another being 
provided to vary the spacing therebetween so that the grasping heads can 
be properly positioned to support metal bars 28 of varying lengths. The 
horizontal plate 200 is supported by a bracket 210 fixed at its upper end 
to a support plate 212 positioned beneath an L-shaped carriage 214, the 
plate 212 being rotatable about a vertical axis by a motor 216 whereby 
operation of the motor 216 causes rotation of the horizontal plate 200 and 
the grasping heads 184 carried thereby, as indicated by the direction 
arrow 218. The L-shaped carriage 214 is moveable along guide rails 220 in 
a vertical direction indicated by the direction arrow 222, this vertical 
movement being caused by a conventional cam and follower arrangement (not 
shown) which is operated by a motor 226 mounted on a U-shaped support 228. 
The U shaped support 228 is itself supported on a vertical plate 230 that 
is carried by a moveable block 232 for horizontal movement along guide 
members 234 as indicated by the direction arrow 236, this movement being 
caused by a rotatable screw element 238 threadably engaging the block 232 
and being operating by motor 240 which are mounted on another vertical 
plate 242 that is fixed to an inverted L-shaped support member 244 carried 
by another moveable block 246. The moveable block 246 is also moveable in 
a horizontal direction perpendicular to the horizontal direction of 
movement of the first moveable block 232, such movement being indicated by 
the direction arrow 247 and being caused by a screw element 249 threadably 
engaging the block 246 and rotated by a motor 251 to cause movement along 
the guide elements 253, this entire arrangement being fixed to the 
previously described superstructure 194. 
Thus, it will be understood that the grasping heads 184 are moveable toward 
and away from one another so as to be able to engage and support metal 
bars of various lengths, and the metal bar 28 can then be manipulated and 
positioned relative to the angle irons in a manner to be described 
presently, and it will be appreciated that the metal bars 28 can be moved 
and manipulated in virtually any direction in view of the compound 
movements of the turret arrangement illustrated in FIG. 7, namely the 
rotational movement indicated by direction arrow 218, the vertical 
movement indicated by direction arrow 222, and the X-Y horizontal movement 
indicated by the direction arrows 236 and 248. 
The previously described moveable platform 154, which carries the moveable 
horizontal support 148 thereon, also carries thereon welding equipment 18 
at one side of the assembly station 16, and it will be understood that the 
welding equipment on the other side of the assembly station 16 (see FIG. 
1) is identical to that illustrated in FIG. 8 except that it is mounted on 
a fixed beam 150' forming part of the frame 150 rather than on a moveable 
platform. The welding equipment 18 includes a welding head 248 on which 
are mounted a copper welding tip 250, through which passes a flux cored 
wire, and a position sensor 252 that is moveable into and out of an 
operator 254, the sensor preferably being of a type like Model LRT-7500 
manufactured by Teknar EMC in Fenton, Mo. and the sensor including a 
controller that is preferably like Model Cylcon Series 5000 manufactured 
by the same company. As will be explained in greater detail below, the 
sensor 252 is operated to move outwardly from the operator 254 until it 
makes contact with anything in its path, whereupon it stops and generates 
a signal that is a function of the location of the item contacted by the 
sensor 252. The welding head 248 is rotatably mounted on a shaft 256 that 
is rotated through a gear drive 258 by an air cylinder 260, this 
rotational movement of the welding head 248 being indicated by the 
direction arrow 262 in FIG. 8. This entire arrangement is carried on an 
L-shaped support 264 which is rotatable about a vertical axis by a motor 
266 as indicated by the direction arrow 268. The motor 266 and the 
L-shaped support 264 are mounted on a support plate 270 that is moveable 
in a vertical direction along guide members 272 by a conventional cam and 
follower arrangement (not shown) driven by a motor 276, this vertical 
direction of movement being indicated by the direction arrow 278. The 
guide members 272 are supported by the support 274, which is fixed to a 
plate 275 mounted on a block 282 that is moveable in a horizontal 
direction (see direction arrow 284) by a screw 286 rotated by a motor 288, 
all of which is in turn mounted on a vertical extension 290 that is moved 
horizontally (see direction arrow 292) along guides 294 by a screw 296 
rotated by a motor 298. Since all of the various drive screw members 
associated with the welding equipment 18 are located at ground level and 
therefore can present safety hazards when they are rotating, all of these 
screw members are preferably covered by an accordion-shaped flexible cover 
300. 
As was the case with the grasping heads 184 described above, the welding 
heads 248 can be moved relative to the platform 154 through a wide range 
of positions by virtue of the compound movements indicated by the 
direction arrows 262, 268, 278, 284, and 292. 
A mechanism is also provided on both sides of the assembly station 16 for 
firmly pressing together the angle irons 108', 108" and the metal bars 28 
positioned therebetween for welding so that an improved weld is formed at 
the points of abutment. One of these mechanisms is illustrated in FIG. 5 
adjacent the fixed horizontal support 146, but it will be understood that 
an identical mechanism is also positioned on the platform 154 adjacent the 
other moveable horizontal support 148. This mechanism includes a 
vertically extending transport member 302 that is fixed to a horizontally 
extending drive belt 304 driven by a motor 306 so that operation of the 
motor 306 will result in the vertical transport member 302 moving in a 
horizontal direction along and closely adjacent the fixed horizontal 
support 146 as indicated by the direction arrow 308. Mounted on the 
transport member 302 is an air cylinder 310 having air inlet and outlets 
312, and having a pressing piston 314 which is moved vertically in an 
upward and downward direction by the air cylinder 310. The pressing piston 
314 is positioned directly above the fixed horizontal support 146 so that 
when, at the assembly station 16, a metal bar 28 is positioned between the 
two pairs of angle irons 108' and 108" in preparation for welding, the air 
cylinder 310 is operated to lower the pressing piston 314 into contact 
with the upper angle iron to firmly press the angle irons and the metal 
bar sandwiched therebetween firmly together in preparation for welding. 
FIG. 5 also illustrates an arrangement for forming a camber in one chord 
member of the finished joist made by the apparatus of the present 
invention, namely the chord member that will be the top chord member when 
the joist is placed across a span in a load bearing application. The beam 
316 which supports the fixed horizontal support 146 is hollow, and mounted 
within the beam 316 is a plate 318 that extends longitudinally along the 
axis of the beam 316, and the plate 318 has fixed thereto at predetermined 
spacings along its length pairs of connecting rods 320 that extend through 
the wall of the beam 316 to a connection with a U-shaped pressure plate 
322 that extends longitudinally along the outside of the beam 316. The 
upper horizontally extending leg of the U-shaped pressure plate 322 is 
normally spaced from a pressing bar 324 that forms the upper horizontal 
support 146 so that the vertically extending flange of the bottom angle 
iron 108' (a small portion of which is illustrated in FIG. 5) is freely 
moveable in such spacing during advancement of the joist. An inflatable 
hose member 326 extends longitudinally within the beam 316 between the 
wall thereof and the plate 318, the hose member 326 being shown in FIG. 5 
in its normal collapsed condition. However, at some point between each 
indexing movement of the angle irons during the joist making process, the 
hose member 326 is fully inflated with fluid from any convenient source 
(not shown), and the inflation of the hose member 326 urges the plate 318 
away from the side wall of the beam 316 so that the connecting rods 320 
will press the U-shaped pressure plate 322 toward the beam 316 and the 
upper horizontal leg of the U-shaped pressure plate will firmly press the 
vertical flange of the angle iron 108' against the pressure bar 324. The 
outside vertical surface of the pressure bar 324 is formed with a gradual 
convex or bowed shape from one of its ends to the other, and when the 
flange of the angle iron 108' is pressed thereagainst by the U-shaped 
pressure plate 322 it imposes enough force to bend the flange into the 
shape of the reference surface of the pressure bar 324, and the 
accumulation of these bends along the entire length of the lower chord 
member of the finished joist will form the desired camber in that chord 
member to such an extent that the camber requirements of the Steel Joist 
Institute are met. 
Except for the hydraulic cylinder 36 which operates the cutting block 32, 
all of the various cylinders described above are preferably conventional 
pneumatic cylinders having a pressurized air input that can be controlled 
through electronic signals generated by the control panel 26 to carry out 
the various cylinder-operated functions described in detail above. FIG. 23 
is a diagrammatic illustration of the control system for the apparatus of 
the present invention showing all of the aforesaid cylinders and other 
control components which receive signals from and/or transmit signals to 
the CPU in the control panel 26. 
To operate the apparatus of the present invention which is described above, 
the design criteria for the particular joist to be made by the apparatus 
is fed into the CPU at the control panel 26 which is programmed to 
determine, in proper sequence, the length and diameter size for each 
linear metal bar 28 that is to be used in forming the web for that 
particular joist, and the CPU generates an output signal that is 
transmitted to the controls for the motor 40, and air cylinders 36 and 52 
which, as described above, advance, in the proper sequence, the metal bar 
stocks 28, each of which is of the correct diameter and is advanced and 
cut by the cutting block 32 to form each metal bar with the correct design 
length. As each metal bar is cut at the cutting station 10, it is grasped 
by the clamp 80 at the transfer station 12 which extracts the metal bar 28 
and which is then moved vertically and horizontally as described above 
until the cut metal bar 28 is located above the hopper 82, whereupon it is 
dropped into the hopper 82 and is guided into the slot 88 thereof. 
Four appropriate angle irons are manually fed along the guide rods 110 and 
the idler rolls 132 as described above until each angle iron reaches its 
associated limit switch 126 which generates a signal that is transmitted 
to the CPU which generates an output signal that operates the air cylinder 
144 to move the pressure roller 124 against its associated angle iron and 
press it against its associated drive member 122 or 134, and the motors 
128 and 136 are operated by the CPU to advance the angle irons for a 
predetermined distance into the assembly station 16, whereupon the 
movement of the angle irons 108' and 108", is stopped. Again, depending on 
the design criteria for the particular joist being made, the control panel 
26 transmits a control signal to the motor 158 which moves the platform 
154 toward or away from the stationary angle iron support 146 until the 
correct lateral chord spacing for the joist is obtained. Next, the motor 
100 is operated to advance the finger 92 along the slot 88 to push the 
metal bar 28 therein into the cradle portions 186 of the grasping heads 
184 which have been positioned by the motor 28 at the exact predetermined 
spacing required for the particular length of that metal bar 28, and the 
clamping pins 188 are then operated to securely hold the metal bar 28 in 
place in the grasping heads 184. The aforesaid proper spacing between the 
grasping heads 184 is such that the midpoint of the metal bar is equally 
spaced from the two grasping heads 184 and lies on the axis of rotation of 
the vertical supports 210. The motor 226 is then operated by the CPU to 
raise the grasping heads 184 and the metal bar therebetween to an 
appropriate height, and the motors 240 and 252 of the turret equipment are 
then operated to move the grasping heads 184 and the metal bar 28 to a 
position above and intermediate the two pairs of angle irons 108' and 108" 
at the assembly station 16, with the metal bar 28 extending generally 
parallel to the angle irons 108' and 108". The motor 226 is then again 
operated by the CPU to lower the grasping heads 184 and the metal bar 28 
to a position between the two pairs of angle irons and at a level 
corresponding to the spacing between the angle irons 108' and 108" in each 
pair. At this point, the motor 178 is operated to raise the block 174 on 
each side of the assembly station 16 by a small increment of movement, and 
since the block 174 is integrally connected to the entire support and 
drive arrangement for the upper angle irons 108' in each pair, this 
movement results in a slight increase in the spacing between the spaced 
horizontal flanges of the upper and lower angle irons 108' and 108", the 
exact distance being determined by the CPU depending on the diameter of 
the metal bar 28 so as to provide a predetermined clearance when the ends 
of the metal bar 28 are moved between the spaced angle irons. After this 
increased spacing has been established, the motor 216 is operated for a 
precise period of time by the CPU so that the grasping heads 184 and the 
metal bar 28 are rotated about the axis of rotation of the vertical 
supports 210, and, as noted above, since the midpoint of the metal bar is 
midway between the grasping heads 184, this midpoint falls on the 
aforesaid axis of rotation so that the motor 216 can be operated to 
position the metal bar with its end portions between the two pairs of 
spaced angle irons and with the metal bar 28 extending between such pairs 
of angle irons at the precise angle required at that particular part of 
that particular joist as determined by the particular design criteria for 
that joist. Just prior to the ends of the metal bar 28 being positioned 
between the two pairs of angle irons, the clamping fingers 172, 177 are 
operated as described above to insure that there is adequate spacing 
between the angle irons in each pair to readily receive the ends of the 
metal bar 28. After the ends of the metal bar 28 have been positioned in 
this manner between the two pairs of angle irons, the motor 178 is again 
operated to lower the block 174, and the clamping fingers 172, 177 are 
operated to release the angle irons, all of which causes the upper angle 
iron 108' in each pair to be lowered until it abuts the top surface of the 
adjacent end of the metal bar 28, after which the motor 306 is operated to 
move the vertical transport 302 until the pressure piston 314 is properly 
positioned above the upper angle iron 108', whereupon the air cylinder 310 
is operated to move the pressure piston 314 downwardly to press the angle 
irons 108' and 108" together so that there is firm abutment between these 
angle irons and the ends of the metal bar 28 sandwiched therebetween so 
that they are ready for the welding operation. 
One of the unique features of the present invention which makes feasible 
the fully automatic welding of the several components of a joist is the 
sequence by which the metal bars 28 are positioned between the two pairs 
of angle irons 108', 108" and the points at which the welds are applied, 
this sequence being diagrammatically illustrated in FIGS. 10-16, which 
show the welding sequence in a perspective diagrammatic view, and 
corresponding FIGS. 17-22 which show the same sequence of welding 
operations, but in a diagrammatic side view. To better understand the 
welding sequence, the joist illustrated in FIGS. 10-16 has been indexed 
through indexing steps so that several different metal bars are shown, 
these metal bars being designated as "BAR 0" for the first metal bar 
positioned between the angle irons in this particular sequence, "BAR 1" 
for the second metal bar positioned between the angle irons in the same 
sequence, and "BAR 2" for the third bar in the sequence. 
The first step in the sequence is illustrated in FIG. 10 and corresponding 
FIG. 17, which show that the welding head 248 has been properly positioned 
in the general vicinity of the ends of BAR 1 which has just been 
positioned between the two pairs of angle irons 108', 108" as described 
above, this positioning of the welding head 248 being accomplished by the 
coordinated operation of the motors 266, 276, 288 and 298 (see FIG. 8) 
under the control of the CPU. The position sensor 252 is extended 
outwardly from its controller 254 until it contacts the end of BAR 1 as 
shown in FIG. 17, and a signal is generated which is a function of the 
exact position of the end of the metal bar, after which the sensor 252 is 
retracted and the welding head 248 is rotated about its horizontal axis as 
indicated by the direction arrow 262 in FIG. 8 until the welding tip 250 
is positioned so that it can be advanced toward the end of BAR 1 and the 
sensor 252 is below the welding tip 250 so that it does not interfere with 
this movement. Since the sensed position of BAR 1 has been transmitted to 
the CPU, the CPU then operates the appropriate motors associated with the 
welding head 248 so that it is advanced by a distance that puts the flux 
cored wire passing through welding tip 250 in contact with the point of 
abutment between the top surface of BAR 1 and the upper angle iron 108' as 
shown in FIGS. 11 and 18. An electric current is then passed through the 
welding tip 250 in accordance with conventional welding technology, and 
the weld is made. The welding head 248 is then withdrawn from its welding 
position, and it is relocated adjacent the end of BAR 0 (the upper surface 
of which has already been welded to the upper angle iron 108' in a 
previous welding sequence), and the welding head 248 is again advanced 
until the welding tip 250 contacts the point of abutment between the lower 
surface of BAR 0 and the bottom angle iron 108" as shown in FIGS. 12 and 
19. It should be noted at this point that the position sensor 252 could be 
used prior to the welding at the bottom surface of BAR 0, but since the 
position of the end of BAR 0 has already been sensed by the position 
sensor 252 in the preceding welding sequence, it is generally not 
necessary to use the position sensor 252 a second time. 
After the welding at BAR 0 has been completed and the welding head 248 
withdrawn, the next step in the sequence is to advance the partially made 
joist by a predetermined length which, again, is controlled by the CPU 
depending on the design criteria for the particular joist being formed. 
The partially formed joist is advanced or indexed by operation of the four 
drive members 122, 134, and this advancement is represented 
diagrammatically in FIG. 13. After the partially formed joist has been 
indexed and has come to a stop, the upper angle irons 108' are raised a 
small distance by the moveable block 174 and the clamping fingers 72, 77 
(FIG. 5) as described above, and the next metal bar in the sequence, which 
is designated as BAR 2 in FIG. 13, is positioned between the two pairs of 
angle irons in a predetermined angular relationship therebetween by the 
manipulating and grasping equipment 20, after which the upper angle irons 
108' are moved downwardly into abutment with the top surface of BAR 2 and 
the pressure piston 314 is moved vertically to press the components 
together, all in the manner described above. It should be noted at this 
point that the small increment of movement of the upper angle irons 108' 
does not effect the integrity of the completed weld at the ends of BAR 0 
because the increment of vertical movement is small, and the linear 
spacing between the ends of BAR 0 and the point at which the upper angle 
irons 108' are raised to receive BAR 2, when combined with the inherent 
resiliency of the upper angle irons 108', result in the upper angle iron 
108' deflecting slightly to accommodate the small increment of vertical 
movement without affecting the integrity of the welds at BAR 0. On the 
other hand, as best illustrated in FIG. 20, at the point where upper angle 
iron 108' is raised to its greatest spacing from lower angle iron 108" to 
receive the end of the new BAR 2, the adjacent end of BAR 1 is welded only 
at the top surface thereof to the upper angle iron 108', and it is 
therefore free to separate temporarily from the lower angle iron 108" when 
the upper angle iron 108' is raised to receive the end of BAR 2. 
After the ends of BAR 2 are properly positioned between the two pairs of 
angle irons 108', 108", the next step in the sequence is to sense the end 
of BAR 2 as shown in FIG. 20, and then weld the top of BAR 2 to the upper 
angle iron 108' as illustrated in FIG. 21. Next, the welding heads 148 are 
repositioned by the various motors as described above, and the welding tip 
250 is advanced to finish the welding of BAR 1 by welding the bottom 
surface thereof to the lower angle irons 108". Thereafter, the partially 
formed joist is again advanced or indexed by a predetermined distance, a 
new metal bar is positioned between the two pairs of angle irons, and a 
new sequence of welding begins which repeats the entire sequence described 
above and illustrated in FIGS. 17-22. This welding sequence is continued 
until the entire joist is completed. Depending on the design 
characteristics of the particular joist being made, there may be, and 
usually are, special variations in the welding sequence which must be 
applied to particular areas of the joist, such as the leading and trailing 
end portions of the joist where the metal bars 28 will have a particular 
disposition with respect to the angle irons that is different from the 
ordinary web forming metal bars 28, but the CPU is capable of adjusting 
the welding sequence, where necessary, based on the aforesaid joist design 
input that is initially fed into the CPU. 
Thus, except for the manual loading of the four angle irons into the 
advancing station 14 and the periodic replenishing of the metal bar stocks 
at the cutting station 10, the operation of the apparatus of the present 
invention results in a fully automatic and reliable method of making a 
joist. Moreover, the apparatus is extremely versatile in terms of the 
number of different joist designs that can be made because the pairs of 
angle irons which make up the two chord members can be positioned at a 
wide range of required spacings, and the individual lengths of metal bars 
which make up the web can be selected in terms of diameter size and length 
at the cutting station 10 so that virtually any required design 
characteristics for the web can be accommodated. Moreover, each of the 
individually selected metal bar lengths can be properly located with 
respect to the angle iron chord members in virtually any angular 
relationship thereto so that, again, a wide range of design 
characteristics can be easily accommodated. Finally, the precision with 
which the apparatus of the present invention selects the correct metal 
bar, both in terms of size and length, and the precision with which the 
angle iron chord members and the metal bar members are positioned and 
welded with respect to one another, results in a joist that is extremely 
reliable in construction. 
It will therefore be readily understood by those persons skilled in the art 
that the present invention is susceptible of a broad utility and 
application. Many embodiments and adaptations of the present invention 
other than those herein described, as well as many variations, 
modifications and equivalent arrangements will be apparent from or 
reasonably suggested by the present invention and the foregoing 
description thereof, without departing from the substance or scope of the 
present invention. Accordingly, while the present invention has been 
described herein in detail in relation to its preferred embodiment, it is 
to be understood that this disclosure is only illustrative and exemplary 
of the present invention and is made merely for purposes of providing a 
full and enabling disclosure of the invention. The foregoing disclosure is 
not intended or to be construed to limit the present invention or 
otherwise to exclude any such other embodiments, adaptations, variations, 
modifications and equivalent arrangements, the present invention being 
limited only by the claims appended hereto and the equivalents thereof.