CA2666285C

CA2666285C - Rigging table for assembling trusses and method of use therefor

Info

Publication number: CA2666285C
Application number: CA2666285A
Authority: CA
Inventors: Jerry Muncie
Original assignee: Nucor Corp
Current assignee: Individual
Priority date: 2008-05-23
Filing date: 2009-05-21
Publication date: 2015-09-15
Anticipated expiration: 2029-05-21
Also published as: WO2009143443A3; US10589390B2; US20170036313A1; US8141252B2; US9387558B2; MX2009005470A; US20120032387A1; WO2009143443A2; EP2303504A2; EP2303504A4; US20090289403A1; CA2666285A1

Abstract

A rigging table and methods and systems for assembling trusses using a rigging table. An embodiment of a rigging table includes a base having a generally longitudinal axis and a generally lateral extent, and at least two bunk assemblies moveable along the base in at least the generally longitudinal axis such that each bunk assembly is capable of being positioned on the base relative to another bunk assembly. Each bunk assembly may include a frame extending along the lateral extent of the base, a pair of guides slidably positioned on the frame to move generally transverse to the longitudinal axis of the base toward and away from each other and able to be fastened in position on the frame, and a pair of automated clamp members each positioned relative to and moveable with one of the guides on the frame, to accommodate assembly of different sized trusses.

Description

RIGGING TABLE FOR ASSEMBLING TRUSSES
AND METHOD OF USE THEREFOR
BACKGROUND AND SUMMARY

[0001] The present invention relates to rigging tables, and to methods and systems for assembling trusses using a rigging table.

[0002] Various processes and techniques have been used to manually fabricate steel open-web trusses. Such fabrication techniques may involve processes including cut-out, rigging, welding, inspection, and painting operations. The welding operation can be the bottleneck or rate-limiting operation limiting production capacity. In a cut-out operation, steel angle and rod chord and web components are cut to length with hydraulic shears, cut-off dies, hydraulic presses, or other cutting devices. The cut-out operation may further include shaping the end of the web components to form a desired shape and size. In a rigging operation, assembly workers, or riggers, arrange the sized components in proper position and clamp and tack-weld the components in place. In a welding operation, a team of welders apply structural welds at component connections to give the truss strength. In an inspection operation, an inspector verifies material sizes, component lengths, welds, and positions. In a painting operation, a truss is dipped in a tank of coating material, such as a water-based primer, drained of excess primer, dried, and then loaded onto a transport out of the plant.

[0003] An assembly table or rigging table may be used, which includes fixtures for positioning the chord and web components in position while the components are clamped and tack-welded together. The long (e.g., up to 65 feet) structural components at the top and bottom of the trusses are known as chords. Chords may be supplied from a position behind the riggers on either side of the rigging table. In the past, the riggers had to turn away from the table, work together to lift a chord overhead, turn back toward the table while holding the chord, and lower the chord into the appropriate fixtures on the table. Once the riggers added the shorter web components, or webs, to the chord portion on the table, a second chord portion may be added.
The components were then clamped and tack welded together. In the past, the riggers typically used hand clamps for this purpose. The riggers then send the rigged truss to the welding area on transfer rollers.

[0004] Manual lifting of the chords can be inefficient. When lifting heavy chords overhead, the riggers take time and precautions to handle the chords safely. Manual hand clamping of truss components is also inefficient, requiring hand strength and operator judgment as to placement.
[00051 What has been needed is a rigging table that automates assembly of trusses of different sizes and allows easy adjustability.

[0006] A rigging table is presently disclosed for assembling trusses comprising:
a) a base having a generally longitudinal axis and a generally lateral extent;
b) at least two bunk assemblies movable along the base in at least the generally longitudinal axis, each bunk assembly capable of being positioned on the base relative to another bunk assembly;
c) each bunk assembly comprising:
a frame extending along the lateral extent of the base;
a pair of guides slidably positioned on the frame to move generally transverse to the longitudinal axis of the base toward and away from each other and able to be fastened in position on the frame to accommodate assembly of different sized trusses; and a pair of automated clamp members each positioned relative to and moveable with one of the guides on the frame to accommodate assembly of different sized trusses, each clamp member capable of securing an intersection of a chord and one or more webs to facilitate assembly of a truss.

[0007] The guides may be capable of being indexed along the frame in predetermined increments adapted to assembly of different sized trusses and fastened to the frame to facilitate assembly of a truss. As an alternate, each guide may be capable of alternatively being slidable along the frame and fastened in position to facilitate assembly of different size trusses, or being indexed along the frame in predetermined increments adapted to assembly of different sized trusses and fastened to the frame to facilitate assembly of a truss.

[0008] Each bunk assembly may have clamp members each comprising:
a stop portion capable of positioning a chord and one or more webs during assembly of a truss; and a clamp arm having an operative position capable of securing the chords and one or more webs in relation to the stop portion for assembly of the truss, and retracting after the truss is assembled.

[0009] Each clamp member may further comprise an actuator capable of moving the clamp arm to secure the chord and one or more webs during assembly of a truss and retracting the clamp arm after the truss is assembled. Each actuator may include a mechanism selected from the group consisting of a servo mechanism, a hydraulic mechanism, and a pneumatic mechanism, and is capable of driving the clamp arm between the securing and retracting positions. Each actuator may, for example, include two actuating cylinders capable of being extended and retracted, and a chain connected between the two actuating cylinders about a sprocket such that the clamp arm is driven by the sprocket to move between the securing and retracting positions.
Alternatively, each actuator may include a rack and pinion capable of driving the clamp arm between securing and retracting positions.

[0010] Each stop portion may include a nesting portion capable of positioning a chord portion of a truss during assembly. The nesting portion of each stop portion may be formed by an inner block and an outer block enabling the chord portion to be positioned there between.

[0011] The rigging table may further include at least one release member capable of disengaging an assembled truss from the clamp members. A release member may be attached to each frame of each bunk assembly.

[0012] A bunk assembly may include rollers capable of allowing assembled trusses to move generally longitudinally along the base, and at least one tilt arm capable of moving an assembled truss onto the rollers. Each roller may be attached to each frame of each bunk assembly.

[0013] The base of the rigging table may include rails extending along the generally longitudinal axis and are capable of supporting at least two bunk assemblies on a plurality of guide wheels, for example, attached to the frames of the bunk assemblies. The base rails are capable of allowing the bunk assemblies to move on the rails and be positioned to accommodate assembly of different size trusses.

[0014] The base of the rigging table may also include stops adjacent each lateral extent of the base, capable of selectively engaging at least a portion of the frame such that when the frame is positioned relative to the stops adjacent one lateral extent, a zero camber is provided in the assembled truss, and when the frame is positioned relative the stops adjacent the opposite lateral extent, a standard camber is provided in the assembled truss.

[0015] The rigging table may also include conveyors capable of moving chord portions, selected for a given truss to be assembled, into position under the bunk assemblies adjacent the lateral extent of the frames thereof. The rigging table may further include automated arms operative to engage a chord portion positioned under the bunk assemblies and move the chord portion to enable positioning the chord portion relative to the frame and guides for assembly of a truss. The rigging table may include an automated worker guard panel that is capable of moving to enable the chord portion to be moved from beneath the bunk assemblies to above the bunk assemblies for positioning for assembly of a truss, and moving back to facilitate movement of workers adjacent the lateral extent of the base.

[0016] A bunk assembly is disclosed for a rigging table comprising:
a) a frame extending along a longitudinal extent and a lateral extent;
b) a pair of guides slidably positioned on the frame to move generally along the lateral extent toward and away from each other and able to be fastened in position on the frame to accommodate assembly of different size trusses; and c) a pair of automated clamp members each positioned relative to and moveable with one of the guides on the frame to accommodate assembly of different sized trusses, each clamp member capable of securing an intersection of a chord and one or more webs to facilitate assembly of a truss.

[0017] The guides may be capable of being indexed along the frame in predetermined increments adapted to assembly of different sized trusses and fastened to the frame to facilitate assembly of a truss. Alternately, each guide of the bunk assembly may be capable of alternately being slidable along the frame and fastened in position to facilitate assembly of different size trusses, or being indexed along the frame in predetermined increments adapted to assembly of different sized trusses and fastened to the frame to facilitate assembly of a truss.

[0018] Each clamp member of the bunk assembly may include a stop portion capable of positioning a chord and one or more webs during assembly of a truss, and a clamp arm having an operative position capable of securing a chord and one or more webs in relation to the stop portion for assembly of the truss, and retracting after the truss is assembled. Each clamp member may include an actuator capable of moving the clamp arm to secure the components during assembly of a truss and retracting the clamp arm after the truss is assembled.

[0019] Each actuator may include a mechanism selected from the group consisting of a servo mechanism, a hydraulic mechanism, and a pneumatic mechanism, capable of driving the clamp arm between the securing and retracting positions. Each actuator may include, for example, two actuating cylinders capable of being extended and retracted, and a chain connected between the two actuating cylinders about a sprocket such that the clamp arm is driven by the sprocket to move between the securing and retracting positions. Alternatively, each actuator may include a rack and pinion capable of driving the clamp arm between the securing and retracting positions.
[0020] Each stop portion may include a nesting portion capable of positioning a chord portion of a truss during assembly. The nesting portion of each stop portion may be formed by an inner block and an outer block enabling a chord portion to be positioned there between.

[0021] The bunk assembly may include at least one release member capable of disengaging an assembled truss from the clamp members. The release member may be attached to the frame of the bunk assembly.

[0022] The bunk assembly may further include rollers capable of allowing assembled trusses to move generally longitudinally along a base of the rigging table, and at least one tilt arm capable of moving an assembled truss onto the rollers. At least one roller may be attached to the frame of the bunk assembly. The bunk assembly may include a plurality of guide wheels attached to the frame and capable of allowing the bunk assembly to move on rails and be positioned to accommodate assembly of different sized trusses.

[0023] The bunk assembly may further include stops for the guides, on each lateral extent of the bunk assembly, such that when the guides are positioned relative to the stops from one side, a zero camber is provided in the assembled truss, and when the guides are positioned relative to the stops at the opposite side, a standard camber is provided in the assembled truss.

[0024] A method is disclosed of assembling truss elements on a rigging table comprising:
a) assembling at least two bunk assemblies for a rigging table with each bunk assembly comprising a frame extending along a lateral extent and a longitudinal extent, a pair of guides slidably positioned on the frame to move generally along the lateral extent toward and away from each other and able to be fastened in position on the frame to accommodate assembly of different sized trusses, and a pair of automated clamp members each positioned relative to an moveable with one of the guides on the frame to accommodate assembly of different sized trusses, each clamp member capable of securing an intersection of a chord and one or more webs to facilitate assembly of a truss;
b) positioning each bunk assembly along the rigging table in desired relation to another bunk assembly to assemble trusses of a desired size;
c) positioning clamp members along the guides on each bunk assembly in desired relation to the other clamp members to assemble trusses of the desired size;
and d) positioning chords and webs of a truss and actuating the clamp members to hold the chords and webs is desired location to assemble a truss of the desired size.

[0025] The method may further include securing chords and webs of a truss using a clamp arm in relation to a stop portion during assembly of a truss, and at least tack-welding the chords and webs together to assemble a truss. The method may further include the further step of lifting the tack-welded truss upward above the bunk assemblies.

100261 These and other advantages and novel features, as well as details of illustrated embodiments thereof, will be more fully understood from the following description and drawings. Further disadvantages of conventional, traditional, and proposed approaches will become apparent to one of skill in the art, from a description of embodiments of the systems and methods as set forth in the remainder of the present application with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 is a diagrammatical plan view of a bunk assembly used in assembling trusses on a rigging table having a pair of clamp members on guides;

[0028] FIG. 2 is a partial perspective view of an alternate bunk assembly to the bunk assembly of FIG. 1 showing one clamp member with a chain guard removed and the second clamp member removed from the bunk assembly;

[0029] FIG. 3 is a second partial perspective view of the clamp member of the alternate bunk assembly shown in FIG. 2;

[0030] FIG. 4 is a partial perspective view of the clamp arm of FIG. 3 being in a securing position to secure a web between two chord portions during assembly of a truss;

[0031] FIG. 5A is a partial plan view of a clamp member of the bunk assembly of FIG. 1;
[0032] FIG. 5B is a view of the clamp member of FIG. 5A with the chain guard removed;
[0033] FIG. 6A is a side view of the clamp member of FIG. 5B in a retracted position;
[0034] FIG. 6B is a side view of the clamp member of FIG. 5B in a securing position;

[0035] FIG. 7 is a partial section view through the bunk assembly of FIG. 1 through the section marked 7-7 showing a friction lock in a loosened position;

[0036] FIG. 8 is an end view of the bunk assembly of FIG. 1 positioned on a base of a rigging table;

[0037] FIG. 9 is a diagrammatical plan view of a second alternate bunk assembly having a tilt arm for lifting a tack-welded truss upward and onto rollers of other standard bunk assemblies;
[0038] FIG. 10 is an end view of the bunk assembly of FIG. 9 with a raised tilt arm;

[0039] FIG. Il is a diagrammatical plan view showing two of a third alternate bunk assembly each having one clamp member on a guide;

[0040] FIG. 12 is a diagrammatical plan view of a rigging table and associated chord portion conveyors for use in assembling trusses;

[0041] FIG. 13 is a diagrammatical side view of a portion of a rigging table illustrating the relationship between a chord portion conveyor, guard panel, and chord portion lifting arms;
[0042] FIG. 14A is a schematic diagram of an end view of a portion of the rigging table of FIG. 13 showing a chord portion resting on the chord portion conveyor with the guard panel in a closed position;

[0043] FIG. 14B is a schematic diagram of an end view of a portion of the rigging table of FIG. 13 showing a chord portion lifted off of a chord portion conveyor by automated lifting arms with the guard panels in an open position;

[0044] FIG. 15 is a partial perspective view of a chord portion lifting arm in an extended position for lifting a chord portion upward and off of a chord portion conveyor with the guard panel in the closed position; and [0045] FIG. 16 is a partial perspective front view of the chord portion lifting arm in a retracted position before lifting a chord portion off of a chord portion conveyor.

DETAILED DESCRIPTION OF THE DRAWINGS

[0046] A rigging table, for assembling trusses, that includes adjustable bunk assemblies is disclosed. As used herein, the term "truss" means an assembly of chords and webs (e.g., steel chords and webs) as generally used in construction. Such an assembly of chords and webs is sometimes also referred to as a joist or a girder.

[0047] FIGS. 1-11 illustrate various aspects of bunk assemblies 10 and 800 used as part of a rigging table in assembling trusses, in accordance with an embodiment of the present invention.
FIG. 1 illustrates an exemplary embodiment of a bunk assembly 10 having a pair of automated clamp members 20 and used in assembling trusses on a rigging table. FIG. 2 illustrates a first view of an exemplary embodiment of one automated clamp member 20 of the bunk assembly 10 of FIG. 1. FIG. 3 illustrates a second view of an exemplary embodiment of one automated clamp member 20 of the bunk assembly 10 of FIG. 1. FIG. 4 illustrates an exemplary embodiment of a clamp arm 80 of one clamp member 20 of the bunk assembly 10 of FIG. 1 being in a securing position to secure webs 500 between two chord portions 200 during assembly of a truss. Two chord portions 200 may be used to make a single chord.

[0048] At least two bunk assemblies 10 may be used in a rigging table to secure and establish lateral and longitudinal spatial relationships between chord portions 200 and webs 500 of a truss to be assembled. The bunk assembly 10 includes a frame 30 having an extent in a generally lateral direction 40 relative to a base and an extent in a generally longitudinal direction 50 relative to the base. The frame 30 includes an outer frame portion 37 and an inner frame portion 33.

[0049] The bunk assembly 10 also includes a pair of guides 60 slidably positioned on the frame 30 to move generally transverse to the longitudinal axis of the base, or transverse to the longitudinal direction 50, toward and away from each other (i.e., generally in the lateral direction 40). The guides 60 are capable of being fastened in position on the frame 30 to accommodate assembly of different sized trusses. Each guide 60 is capable of being indexed along the frame 30 in predetermined increments adapted to assembly of different sized trusses of predetermined sizes, and fastened to the frame 30 to facilitate assembly of a truss.
Furthermore, each guide 60 may be capable of being slidable along the frame and fastened in position between index positions to facilitate assembly of different size trusses.

[0050] The automated clamp members 20 may each be positioned relative to and moveable with one of the guides 60 on the frame 30 to accommodate assembly of different sized trusses.
Each automated clamp member 20 is capable of securing an intersection of at least one chord portion 200 and one or more webs 500 to facilitate assembly of a truss.
Furthermore, each automated clamp member 20 includes a stop portion 70 capable of positioning at least one chord portion 200 and one or more webs 500 during assembly of a truss. As shown in FIG. 3, each stop portion 70 includes an inner block 71 and an outer block 72 forming a nesting portion 73 there between, enabling a chord portion 200 to be positioned within the nesting portion 73.

[0051] As shown in FIGS. 2-4, each automated clamp member 20 includes a clamp arm 80 having an operative position capable of securing at least one chord portion 200 and one or more webs 500 in relation to the stop portion 70 for assembly of a truss, and retracting after the truss is assembled. Each automated clamp member 20 also includes an actuator 90 capable of moving the clamp arm 80 to secure at least one chord portion 200 and one or more webs 500 during assembly of a truss, and retracting the clamp arm 80 after the truss is assembled.

[0052] Each actuator 90 may include two actuating cylinders 91 and 92 capable of being extended and retracted, and a chain 93 connected between the two actuating cylinders 91 and 92 about a sprocket 94. The clamp arm 80 is driven by the sprocket 94 to move between the securing and the retracting positions, as shown in FIGS. 6A and 6B. The chain and sprocket may be covered by a chain guard. FIGS. 513, 6A, and 6B show the assembly with the chain guard removed. Each actuator 90 may include a servo mechanism, a hydraulic mechanism, or a pneumatic mechanism that is capable of driving the clamp arm 80 between the securing and the retracting positions. As an alternative, each actuator 90 may include a rack and pinion capable of driving the clamp arm 80 between the securing and retracting positions.

[0053] A bunk assembly 10 may include at least one release member 100 capable of disengaging an assembled truss from the clamp members 20. The release members 100 may be attached to the frame 30 of the bunk assembly 10 and are capable of being actuated upward to lift an assembled truss out of and above the clamp members 20. Some bunk assemblies 10 may not have a release member 100. The number of bunk assemblies 10 on the rigging table 10 having at least one release member 100 may be determined by the size and weight of the assembled truss and the lifting capacity of each release member.

[0054] A bunk assembly 10 may include a roller 110 capable of allowing an assembled truss to move generally longitudinally along the rigging table 10. The roller 110 is attached to the frame 30 of the bunk assembly and is capable of being actuated upward such that an assembled truss rolling along the roller 110 may clear the clamp members 20. Typically, a bunk assembly will have a roller I 10 and at least one release member 100. Certain other specialized bunk assemblies such as bunk assembly 800 may not include a roller 110 or release members 100.
Instead, certain other specialized bunk assemblies 800 may include a tilt arm mechanism 810 as shown and described later herein with respect to FIGS. 9 and 10.

100551 FIG. 2 illustrates an exemplary embodiment of a track 400 including a friction lock slot 410 and a track recess 420 as part of the inner frame portion 33 of the frame 30. As shown in FIG. 7, a corresponding runner, such as a protrusion or other feature, along the bottom of the guide 60 is positioned within the track recess 420 enabling the guide to move along the track in the lateral direction 40. By moving the guides 60 along the tracks 400, the clamp members 20 may be moved closer to each other or further away from each other to establish a lateral extent of a truss to be assembled. A friction lock 61 extending through the friction lock slot 410 may be used to secure the guide 60 in a desired position. As an example, the friction lock 61 may include a nut and bolt assembly such that the friction lock 61 may be tightened or loosened within the friction lock slot 410. The runner along the bottom of the guide 60 is positioned within the track recess 420 and serves, along with the friction lock 61 through the friction lock slot 410, to hold the guide 60 in place with respect to the frame 30. The guide 60 rests on the top surfaces of the inner frame portion 33 of the frame 30, including side rails 34 of the inner frame portion 33 and a central index rail 35 of the inner frame portion 33 as shown in FIGS. 1 through 4.

[0056] The central index rail 35 may include a plurality of indexing recesses, or teeth, capable of laterally positioning the guide 60 along the frame. The teeth of the central index rail 35 are spaced in predetermined increments, such as for example, one inch increments, or two centimeter increments, or other spaced increments as desired. A pop-lock 62, passing through or adjacent the guide 60, may be used to index the guide 60 to the teeth of the central index rai135.
The guide 60 may be moved laterally along the frame 30 and track 400 when the pop-lock 62 is released and the friction lock 61 is loosened. When placed in a desired lateral position along the index rail 35, the pop-lock 62 may be locked between the teeth of the index rail 35 and the friction lock 61 may be tightened to securely hold the guide 60 in place.
Alternatively, the guide 60 may be secured between two teeth positions by tightening the friction lock 61 in the desired position with the pop-lock 62 remaining released.

[0057] As shown in FIG. 8, the bunk assembly 10 of FIG. 1 may be positioned on a rigging table base 600. The base 600 may include two substantially parallel rails 610 extending along the generally longitudinal direction 50 and capable of supporting at least two bunk assemblies 10 on a plurality of guide wheels 31 attached to the frames 30 of the bunk assemblies. The guide wheels 31 allow the bunk assemblies 10 to move on the rails 610 and be positioned or spaced longitudinally with respect to each other to accommodate assembly of different sized trusses.
The wheels 31 along one rail 610 may be configured with a v-groove or other shape adapted to engage a corresponding shape on the rail 610 as shown in FIGS. 1 and 8. The v-groove or other shape guide wheel 31 enables the wheel to remain aligned with the rail 610.
When the wheels 31 along one side of the frame are adapted to engage a corresponding shape on the rail 610, the wheels 31 on the other side of the frame may be capable of accommodating variations in the distance between the rails 610 caused by normal manufacturing tolerances, wear, environment, damage, or other dimensional differences, such as by wheels having a smooth circumference not engaging the rail.

[0058] The bunk assemblies 10 may be positioned with respect to each other along the rails 610 to provide desired longitudinal distance or spacing between clamp members 20 of adjacent bunk assemblies. The minimum longitudinal distance between clamp members 20 of a plurality of bunk assemblies may correspond to the width of the frame 30. When two adjacent bunk assemblies 10 are butted against each other (bunk frames touching) in the longitudinal direction 50, the distance from the clamp member of one bunk assembly to the corresponding clamp member of the adjacent bunk assembly may be about the width of the frame 30, which in the configuration of FIG. 1 may be about thirty inches (about 0.75 meters).
Additionally, adjacent bunk assemblies 10 may be spaced apart as desired during operation of the rigging table.
Typically, the distance between corresponding clamp members 20 from one bunk assembly to the next is determined based on the structural design of the truss to be assembled, and typically is less than about six feet (about 1.8 meters).

[0059] The bunk assemblies 10 may be capable of being slidable along the rails 610 and fastened in position to facilitate assembly of different size trusses.
Further, the bunk assemblies may be capable of being indexed along the base in predetermined increments to facilitate assembly of desired trusses. The base 600 may include an indexing guide having a plurality of indexing recesses, or teeth, capable of longitudinally positioning the bunk assemblies along the base. An indexing guide may be adjacent one or both of the rails 610, and may be integral with each rail. The indexing teeth may be spaced in predetermined increments, such as for example, one inch increments (about 2.5 centimeters), or two centimeter increments (about 0.8 inch), or other spaced increments as desired. As shown in FIG. 8, spring-loaded pop-pins 730 may be attached to the frame 30 at each lateral extent such that the pop-pins 730 may engage the indexing guide of the base 600 in order to locate a bunk assembly 10 longitudinally along the base 600. The pop-pins 730 at each lateral extent of the bunk assembly 10 may have release cables connected together such that both pop-pins may be disengaged together by actuating the connected release cable.

[0060] The inner portion 33 of the frame 30 is capable of being positioned along the lateral direction 40 within the outer portion 37 of the frame 30. As best shown in FIG. 1, by loosening at least one friction lock 32, the inner frame portion 33 is slidable within the outer frame portion 37 from one lateral extent to the other. The inner frame portion is laterally positionable within the outer frame portion so that the inner frame portion 33 and clamp members 20 along the base 600 can be positioned to provide a desired camber along the length of the assembled truss.

[0061] FIG. 8 illustrates a view of the bunk assembly 10 of FIG. 1 positioned on a base 600 of a rigging table. To assist in positioning the plurality of clamp members to provide the desired camber, the base 600 may include longitudinally extending camber rails, or camber stops 710, adjacent one or both lateral extents of the base 600 bounding the lateral movement of the inner frame portion 33. A guide portion 720 of the inner frame portion 33 is capable of selectively engaging the camber stops such that the inner frame portion 33 may be positioned relative to or abutting the camber stop 710 adjacent one lateral extent, or moved in the lateral direction 40 toward a camber stop adjacent the opposite lateral extent. When a camber stop is not provided along a lateral extent, the movement of the inner frame portion 33 may be bounded by the outer frame portion 37 or the rail 610, or the base 600, any of which may be adapted to provide zero camber in the assembled truss. Alternately, to provide zero camber in the assembled truss, a straight camber stop may be provided to align the inner frame portions with zero camber. The camber stops 710 may be positioned adjacent to the rai1610, or may be integral to the rail.

[0062] The camber rails, or camber stops 710, may have an arcuate longitudinal face along the base 600 such that a plurality of inner frame portions 33 may be positioned relative to the arcuate face along the base providing a camber corresponding to the arcuate radius. The camber stop may be provided with a radius of curvature determined by an industry standard, a structural design requirement, or other radius. While the camber stops may have any desired radius of curvature, it is contemplated that the rigging table be provided with a radius of curvature that is typically assembled on the table, or a"standard camber." In one example, the standard camber may be a radius of curvature of about 3,600 feet (about 1097.3 meters). In the configuration of FIG. 8, the outer portion 37 of frame 30 provides the inner frame stop adjacent one lateral extent, and a camber stop 710 is provided adjacent the opposite lateral extent. In this embodiment, the plurality of bunk assemblies may be positioned relative to or against the camber stop 710 during assembly of a truss to provide assembled trusses having a slight curve, or camber corresponding to the arcuate radius of the camber stop.

[0063] The friction lock 32 may include a nut and bolt assembly passing through the outer portion 37 and inner portion 33 of the frame 30 capable of securing the inner frame portion within the outer frame portion 37. The friction lock 32 may be used to secure the inner portion 33 of the frame 30 against either lateral extent bounded by the camber stop, the rail 610, or the outer frame portion 37, to provide the desired camber. Alternately, the friction lock 32 may be used to secure the inner frame portion 33 positioned between the stops at the lateral extents to provide, for example, a custom camber. When assembling a truss having a defined camber, a center of a truss to be assembled may be aligned with the center of the camber rail 710 to be able to assemble trusses of different lengths having the same camber (i.e,. radius of curvature).
Furthermore, the camber rail 710 may be changed out with another camber rail to accommodate the assembly of trusses having other radii of curvature.

[0064] FIG. 9 illustrates an exemplary embodiment of a specialized bunk assembly 800 having a tilt arm 810 for tilting a tack-welded truss upward and onto the rollers 110 of standard bunk assemblies 10. FIG. 10 illustrates an exemplary embodiment of the tilt arm 810 of FIG. 9 in a lifted position. Several specialized bunk assemblies 800 and tilt arms 810 may be positioned along the length of the base 600 of the rigging table. After a truss is assembled (e.g., tack-welded) on the rigging table, an operator may release all the clamp arms 80 via a single point release. Alternately, operators may release each clamp arm 80 at each bunk assembly 10. Then, the release members 100 within the standardized bunk assemblies 10 are actuated to lift up the assembled truss to clear the upper portion of the bunk assemblies 10, and the rollers 110 are actuated to lift upward. The tilting arms 810 are then actuated to move the assembled truss onto the rollers 110. The truss may be moved onto the rollers in a generally vertical orientation. The tilting arms 810 may be moved by actuator 820, which may be actuated hydraulically, pneumatically, or by other actuators. The riggers at the rigging table may assist in guiding the assembled truss onto the rollers 110 and then move the truss along the table on the rollers. Once an assembled truss is removed from the rigging table, the operators (riggers) may provide next chord portions 200 and webs 500 to the bunk assemblies for assembly of the next truss.

[0065] The tilt arm 810 may be attached to the frame 30 of the bunk assembly 800 and is capable of being actuated such that a bottom portion of the tilt arm 810 slides from one lateral extent of the bunk assembly 800 toward the opposite lateral extent of the bunk assembly 800 as the tilt arm 810 operates. This enables the tilt arms 810 to lift an assembled truss to a generally vertical position such that the assembled truss rests on the rollers 110. The tilt arms 810 may include serrated edges 811 to help catch the assembled truss as the assembled truss is tilted upward. The assembled truss may then be rolled, in the longitudinal direction 50, off of the rigging table by the rigging table operators.

[0066] Other specialized bunk assemblies may be provided. Such other specialized bunk assemblies may include end bunk assemblies that are customized to assemble a certain type of end on each side of a truss. Such end bunk assemblies may not have, for example, a roller 110 or a tilt arm 810. Furthermore, such end bunk assemblies may include only one clamp member 20, such as an end bunk assembly 850, 850' shown in FIG. 11, and may be narrower (in the longitudinal direction 50) than the bunk assembly 10 of FIG. 1. Other variations of end bunk assemblies are possible as well, depending on the design of the end of the desired truss.

[0067] The rigging table may include a material handling apparatus to selectively position chord portions between the operators, or riggers, and the rigging table to reduce the distance and motion needed to move the chord portion to the clamp members 20. The material handling apparatus may be capable of moving chord portions, selected for a given truss to be assembled, into position under or below the bunk assemblies adjacent the lateral extent of the frames 30, and having automated arms operative to engage a chord portion positioned under or below the bunk assemblies and move the chord portion to enable positioning of the chord portion relative to the frame 30 and guides 60 for assembly of a truss.

[0068] FIG. 12 is a schematic diagram of a top view of an exemplary embodiment of a rigging table 1000, having a generally longitudinal axis 51 in a generally longitudinal direction 50, and associated chord portion conveyors 1010, 1020 and 1030 for use in assembling trusses.
The various bunk assemblies rest on top of the rails of the base 600 of the rigging table 1000 as described previously herein.

[0069] As shown in FIG. 12, chord portions 200 are provided on a material rack 1050. A
chord portion 200 may be removed from the material rack 1050, by operators or by a removal device, and onto the first longitudinal conveyor 1010 which is offset from the base 600 of the rigging table 1000. The chord portion 200 travels down the first longitudinal conveyor 1010 in the longitudinal direction 50 toward a kickoff position 1060 where the chord portion 200 is kicked off of the first longitudinal conveyor 1010 and onto a lateral conveyor 1020. In this manner, chord portions 200 are queued along the lateral conveyor 1020. When a chord portion 200 is needed, the chord portion 200 transfers from the lateral conveyor 1020 to a second longitudinal conveyor 1030. As shown in FIG. 12, the second longitudinal conveyor 1030 may be positioned adjacent the end of the lateral conveyor 1020, and the chord portions may transfer from the lateral conveyor 1020 to the second longitudinal conveyor 1030 by dropping from the lateral conveyor onto the second longitudinal conveyor. Alternately, a kick-off arm may be used to kick the chord portion 200 from the lateral conveyor 1020 to the second longitudinal conveyor 1030. The first longitudinal conveyor 1010 may be positioned at a higher elevation than the second longitudinal conveyor 1030. After one chord portion 200 advances along the second longitudinal conveyor 1030 away from the kickoff position 1060, another chord portion may be transferred from the lateral conveyor 1020 to the second longitudinal conveyor so that chord portions 200 are queued along the second longitudinal conveyor.

[0070] The chord portion 200 travels along the second longitudinal conveyor 1030 in the longitudinal direction 50 and stops beneath the rigging table 1000 in the truss assembly area 1070 to be used in the assembly of a truss on the rigging table 1000. The material handling apparatus and the process of providing chord portions 200 from a material rack 1050 to the truss assembly area 1070 beneath the rigging table 1000 on the second longitudinal conveyor 1030 is duplicated on the opposite side of the rigging table 1000. In this manner, chord portions 200 are automatically fed to the truss assembly area 1070 beneath the rigging table 1000 on both sides of the rigging table 1000 as shown in FIG 12.

[0071] FIG. 13 is a schematic diagram of a side view of an exemplary embodiment of a portion of the rigging table 1000 of FIG. 12 illustrating the relationship between the second longitudinal conveyor 1030, a worker guard panel 1110, and automated chord portion lifting arms 1120. The worker guard panels 1110 protect the operators, or riggers, on either side of the rigging table 1000 from the mechanism of the conveyor 1030. The worker guard panels 1110 are capable of moving to enable the chord portion to be moved from beneath the bunk assemblies to above the bunk assemblies for positioning for assembly of a truss, and moving back to facilitate movement of workers adjacent the lateral extent of the base. A
plurality of automated lifting arms 1120 may be positioned along the rigging table and are capable of automatically extending to lift a chord portion 200 off of the conveyor 1030 upward toward the base 600 of the rigging table 1000 when the guard panels 1110 are in an open position. The extended lifting arms 1120 may position the chord portions between the riggers and the rigging table enabling the riggers to lift and move the chord portions onto the frame 30 and guides 60 for assembly of a truss. The automated lifting arms 1120 present a chord member when the guard panels 1110 are in the open position. The guard panels may be segmented between lifting arms 1120, or include apertures at each lifting arm, such that the guard panels may return to a closed position with the lifting arms 1120 in the extended position.

[0072] FIG. 14A is a schematic diagram of an end view of a portion of the rigging table 1000 of FIG. 13 showing a chord portion 200 resting on the chord portion conveyor 1030 with the worker guard panel 1110 in the closed position and the automated lifting arms 1120 in a retracted position. FIG. 14B is a schematic diagram of an end view of a portion of the rigging table 1000 of FIG. 13 showing the chord portion 200 lifted off of the chord portion conveyor 1030 by the automated lifting arms 1120 with the worker guard panel 1110 in the open position.

[0073] The top portion of each lifting arm 1120 may be L-shaped in order to snag or catch the chord portion 200 in the L-shaped top portion and lift the chord portion 200 off of the conveyor 1030. When extended, the arms 1120 may be about the height of the bunk assembly.
Once the arms 1120 are extended with a chord portion 200 in the L-shaped top portion, the guard panels 1110 may be closed (retracted), leaving the arms 1120 extended through the apertures in the panel, so that the operators can approach the chord portion 200, grab the chord portion 200 off the arms 1120, and place the chord portion 200 onto the bunk assemblies.
There may be at least one operator positioned on each side of the bunk assembly. The arms 1120 then retract after the chord portion 200 is lifted from the arms 1120 by the operators. In response to the arms 1120 retracting, the second longitudinal conveyor 1030 may present another chord portion 200 under the base 600 of the rigging table 1000 in preparation for presenting the next chord portion.
This process occurs on both sides of the rigging table 1000.

[0074] When a chord portion 200 is lifted upward off of the conveyor 1030 by the lifting arms 1120, the operators may lift the chord portion 200 and place the chord portion 200 onto the nesting portion 73 of the bunk assemblies 10 and 800, for example. FIG. 15 illustrates an exemplary embodiment of an automated lifting arm 1120 in an extended position for lifting a chord portion 200 upward off of a chord portion conveyor 1030. FIG. 16 illustrates an exemplary embodiment of an automated lifting arm 1120 in a retracted position before lifting a chord portion 200 from the chord portion conveyor 1030.

[0075] A controller is provided capable of receiving inputs from the riggers and activating the rigging table in a desired sequence. The controller may include a computer-based platform such as, for example, a personal computer (PC) or the controller may include a programmable logic controller (PLC), for example. The controller interfaces to the material handling apparatus and the rigging table such that the controller may activate/deactivate various actuators of the material handling apparatus and the rigging table in order to control the flow of material (i.e., chord portions) and in order to control various actuating features of the rigging table. The controller may include a user interface (e.g., a touch screen) enabling a lead operator to manually select various functions to initiate various control commands to the material handling apparatus and/or rigging table.

[0076] Sensors (not shown) may be provided to indicate the position of chord portions 200 in the material handling apparatus, for example, the presence of a chord portion 200 in the truss assembly area 1070, and capable of providing corresponding signals to the controller. Further, sensors may be provided to indicate the position of portions of the rigging table, for example, clamp arms 80, guard panels 1110, lifting arms 1120, and other portions of the rigging table and providing signals corresponding to the position to the controller. The controller may further be capable of receiving signals from the sensors and activating the rigging table in response to the sensor signals.

[0077] For example, during operation, after a truss is assembled on the rigging table 1000 (e.g., tack-welded), the assembled truss may be lifted and tilted upward to be rolled off of the rigging table 1000 as previously described herein, in response to commands from the controller.
The actuation of the release members 1001ifting up the assembled truss may automatically signal the controller to actuate the transfer of a chord portion 200 from the lateral conveyor 1020 to the second longitudinal conveyor 1030 on both sides of the rigging table 1000.
When it is time to present a next chord portion 200 to the operators, the controller may command the actuation of the guard panels 1110 such that the guard panels move into the open position to allow a chord portion to be extended. The guard panel 1110 may move downward like a hinged door, may move laterally, translate downwardly, or otherwise move into the open position. The lifting arm apertures in the guard panels 1110 may have a cut-out or open area that begins below the conveyor 1030 and extends upward such that the lifting arms 1120 may pass through when the guard panels 1110 are opened, and the lifting arms may remain extended when the guard panels are closed.

[0078] When using the rigging table 1000 to assemble a truss, operators place bottom chord portions 200 onto the bunk assemblies and set webs 500 across the bottom chord portions. The webs may be tack-welded to the bottom chord portions. Then, a top chord portion may be lifted up and placed by the operators on top of the webs. Each operator may activate an automated clamp member 20 to close the clamp arm 80 to secure the webs sandwiched between the top and bottom chord portions at each clamping position. The top chord portion may then be tack-welded to the webs. A lead operator may then activate a global release of all the clamp arms 80, via the controller, which retracts all of the clamp arms 80 an initiates lifting of the resultant assembled truss.

[0079] While certain embodiments have been described in the present application, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the claimed invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the claimed invention without departing from its scope. Therefore, it is intended that the claimed invention not be limited to the particular embodiments disclosed, but that the claimed invention will include all embodiments falling within the scope of the appended claims.

Claims

What is claimed is:

1. A rigging table for assembling trusses comprising:
a base having a generally longitudinal axis and a generally lateral extent;
at least two bunk assemblies movable along the base in at least the generally longitudinal axis, each bunk assembly capable of being positioned on the base relative to another bunk assembly;
each bunk assembly comprising:
a frame extending along the lateral extent of the base;
a pair of guides slidably positioned on the frame to move generally transverse to the longitudinal axis of the base toward and away from each other and able to be fastened in position on the frame to accommodate assembly of different sized trusses; and a pair of automated clamp members each positioned relative to and moveable with one of the guides on the frame to accommodate assembly of different sized trusses, each clamp member capable of securing an intersection of a chord and one or more webs to facilitate assembly of a truss.

2. The rigging table as claimed in claim 1, where each guide is capable of being indexed along the frame in predetermined increments adapted to assemble different sized trusses, and fastened to the frame to facilitate assembly of a truss.

3. The rigging table as claimed in claim 1, where each guide is capable of alternatively being slidable along the frame and fastened in position to facilitate assembly of different size trusses, or being indexed along the frame in predetermined increments adapted to assembly of different sized trusses and fastened to the frame to facilitate assembly of a truss.

4. The rigging table claimed in claim 1 where the at least two bunk assemblies have clamp members each comprising:

a stop portion capable of positioning a chord and one or more webs during assembly of a truss; and a clamp arm having an operative position capable of securing the chord and one or more webs in relation to the stop portion for assembly of the truss, and retracting after the truss is assembled.

5. The rigging table as claimed in claim 4 where at least two bunk assemblies have clamp members each further comprising an actuator capable of moving the clamp arm to secure the chord and one or more webs during assembly of a truss, and retracting the clamp arm after the truss is assembled.

6. The rigging table as claimed in claim 5 where each actuator comprises:
two actuating cylinders capable of being extended and retracted; and a chain connected between the two actuating cylinders about a sprocket such that the clamp arm is driven by the sprocket to move between the securing and retracting positions.

7. The rigging table as claimed in claim 6 where each actuator comprises a mechanism selected from the group consisting of a servo mechanism, a hydraulic mechanism, and a pneumatic mechanism, and is capable of driving the clamp arm between the securing and retracting positions.

8. The rigging table as claimed in claim 5 where each actuator comprises a rack and pinion capable of driving the clamp arm between securing and retracting positions.

9. The rigging table as claimed in claim 4 where each stop portion comprises a nesting portion capable of positioning a chord portion of a truss during assembly.

10. The rigging table as claimed in claim 9 where the nesting portion of each stop portion is formed by an inner block and an outer block enabling the chord portion to be positioned there between.

11. The rigging table as claimed in claim 1 further comprising at a least one release member capable of disengaging an assembled truss from the clamp members.

12. The rigging table as claimed in claim 11 where a release member is attached to each frame of each bunk assembly.

13. The rigging table as claimed in claim 1 further comprising:
rollers capable of allowing assembled trusses to move generally longitudinally along the base; and at least one tilt arm capable of moving an assembled truss onto the rollers.

14. The rigging table as claimed in claim 13 where at least one roller is attached to each frame of each bunk assembly.

15. The rigging table as claimed in claim 1 where the base has rails extending along the generally longitudinal axis and capable of supporting at least two bunk assemblies on a plurality of guide wheels attached to the frames of the bunk assemblies, and capable of allowing the bunk assemblies to move on the rails and be positioned to accommodate assembly of different size trusses.

16. The rigging table as claimed in claim 1 where the base further comprises stops adjacent each lateral extent of the base capable of selectively engaging at least a portion of the frame such that when the frame is positioned relative to the stops adjacent one lateral extent, a zero camber is provided in the assembled truss, and when the frame is positioned relative the stops adjacent the opposite lateral extent, a standard camber is provided in the assembled truss.

17. The rigging table as claimed in claim 16 where the stops include longitudinally extending camber rails having an longitudinal face adjacent a lateral extent of the base, the longitudinal face having a desired radius of curvature defining the camber.

18. The rigging table as claimed in claim 1 further comprising:
conveyors capable of moving chord portions, selected for a given truss to be assembled, into position under the bunk assemblies adjacent the lateral extent of the frames thereof; and automated arms operative to engage a chord portion positioned under the bunk assemblies and move the chord portion to enable positioning the chord portion relative to the frame and guides for assembly of a truss.

19. The rigging table as claimed in claim 1 further including an automated worker guard panel capable of moving to enable the chord portion to be moved from beneath the bunk assemblies to above the bunk assemblies for positioning for assembly of a truss, and moving back to facilitate movement of workers adjacent the lateral extent of the base.

20. The rigging table as claimed in claim 1 where the base further comprises stops adjacent each lateral extent of the base capable of selectively engaging a portion of the frame of the bunk assemblies such that when the frames are positioned relative to the stops adjacent one lateral extent, a zero camber is provided in the assembled truss, and when the frames are positioned relative the stops adjacent the opposite lateral extent, a standard camber is provided in the assembled truss.

21. A bunk assembly for a rigging table comprising:
a frame extending along a longitudinal extent and a lateral extent;
a pair of guides slidably positioned on the frame to move generally along the lateral extent toward and away from each other and able to be fastened in position on the frame to accommodate assembly of different size trusses; and a pair of automated clamp members each positioned relative to and moveable with one of the guides on the frame to accommodate assembly of different sized trusses, each clamp member capable of securing an intersection of a chord and one or more webs to facilitate assembly of a truss.

22. The bunk assembly as claimed in claim 21 where each guide is capable of being indexed along the frame in predetermined increments adapted to assemble different sized trusses, and fastened to the frame to facilitate assembly of a truss.

23. The bunk assembly as claimed in claim 21 where each guide is capable of alternatively being slidable along the frame and fastened in position to facilitate assembly of different size trusses, or being indexed along the frame in predetermined increments adapted to assembly of different sized trusses and fastened to the frame to facilitate assembly of a truss.

24. The bunk assembly claimed in claim 21 where each clamp member comprises:
a stop portion capable of positioning a chord and one or more webs during assembly of a truss; and a clamp arm having an operative position capable of securing a chord and one or more webs in relation to the stop portion for assembly of the truss, and retracting after the truss is assembled.

25. The bunk assembly as claimed in claim 24 where each clamp member further comprises an actuator capable of moving the clamp arm to secure the components during assembly of a truss and retracting the clamp arm after the truss is assembled.

26. The bunk assembly as claimed in claim 25 where each actuator comprises:

two actuating cylinders capable of being extended and retracted;

a chain connected between the two actuating cylinders about a sprocket such that the clamp arm is driven by the sprocket to move between the securing and retracting positions.

27. The bunk assembly as claimed in claim 26 where each actuator comprises a mechanism selected from the group consisting of a servo mechanism, a hydraulic mechanism, and a pneumatic mechanism, and is capable of driving the clamp arm between the securing and retracting positions.

28. The bunk assembly as claimed in claim 26 where each actuator comprises a rack and pinion capable of driving the clamp arm between the securing and retracting positions.

29. The bunk assembly as claimed in claim 24 where each stop portion comprises a nesting portion capable of positioning a chord portion of a truss during assembly.

30. The bunk assembly as claimed in claim 29 where the nesting portion of each stop portion is formed by an inner block and an outer block enabling a chord portion to be positioned there between.

31. The bunk assembly as claimed in claim 21 further comprising at least one release member capable of disengaging an assembled truss from the clamp members.

32. The bunk assembly as claimed in claim 31 where the at least one release member is attached to the frame of the bunk assembly.

33. The bunk assembly as claimed in claim 21 further comprising:
rollers capable of allowing assembled trusses to move generally longitudinally along a base of the rigging table; and at least one tilt arm capable of moving an assembled truss onto the rollers.

34. The bunk assembly as claimed in claim 33 where at least one roller is attached to the frame of the bunk assembly.

35. The bunk assembly as claimed in claim 21 further comprising a plurality of guide wheels attached to the frame and capable of allowing the bunk assembly to move on rails and be positioned to accommodate assembly of different sized trusses.

36. The bunk assembly as claimed in claim 21, further comprising stops for the guides on each lateral extent of the bunk assembly such that when the guides are positioned relative to the stops from one side, a zero chamber is provided in the assembled truss, and when the guides are positioned relative the stops at the opposite side, a standard chamber is provided in the assembled truss.

37. A method of assembling truss elements on a rigging table comprising:
assembling at least two bunk assemblies for a rigging table, each bunk assembly comprising:
a frame extending along a lateral extent and a longitudinal extent;
a pair of guides slidably positioned on the frame to move generally along the lateral extent toward and away from each other and able to be fastened in position on the frame to accommodate assembly of different sized trusses; and a pair of automated clamp members each positioned relative to and moveable with one of the guides on the frame to accommodate assembly of different sized trusses, each clamp member capable of securing an intersection of a chord and one or more webs to facilitate assembly of a truss;
positioning each bunk assembly on the rigging table in desired relation to another bunk assembly along a base having a generally longitudinal axis and a generally lateral extent to assemble trusses of a desired size;

positioning clamp members along the guides on each bunk assembly in desired relation to the respective other clamp members to assemble trusses of the desired size;
and positioning chords and webs of a truss and actuating the clamp members to hold the chords and webs in desired location to assemble a truss of the desired size wherein actuating the clamp members comprises applying a clamping force transverse to the lateral direction of the truss at the intersections of the chords and webs between one of said pair of clamp members and a corresponding stop portion on an end of at least one of the respective pair of guides.

38. The method of claim 37, the step of positioning chords and webs of a truss and actuating the clamp members comprising actuating a clamp arm for securing chords and webs of a truss in relation to the stop portion during assembly of a truss.

39. The method of claim 38, comprising the further step of tack-welding the chords and webs together to assemble a truss.

40. The method of claim 39, comprising the further step of lifting the tack-welded truss upward above the bunk assemblies.

41. The method of claim 38, further comprising retracting the clamp arm after the truss is assembled.

42. The method of claim 38, wherein the actuating is performed by actuators, each actuator comprising;
two actuating cylinders capable of being extended and retracted; and a chain connected between the two actuating cylinders about a sprocket such that the clamp arm is driven by the sprocket to move between the securing and retracting positions.

43. The method of claim 38, wherein the actuating is performed by actuators, each actuator comprising: a rack and pinion capable of driving the clamp arm between securing and retracting positions.

44. The method of claim 37, comprising indexing each guide along the frame in predetermined increments to assemble different sized trusses, and fastening each guide to the frame to facilitate assembly of a truss.

45. The method of claim 37, comprising positioning a chord portion of a truss in relation to a nesting portion in each stop portion during assembly.

46. The method of claim 45, where the nesting portion of each stop portion is formed by an inner block and an outer block enabling the chord portion to be positioned there between.

47. The method of claim 37, further comprising disengaging an assembled truss from the clamp members.

48. The method of claim 47, the step of disengaging an assembled truss comprising activating a release member attached to each frame of each bunk assembly.

49. The method of claim 37, further comprising:
tilting an assembled truss onto rollers, and moving the assembled truss along the rollers generally longitudinally along the base.

50. The method of claim 49, where at least one roller is attached to each frame of each bunk assembly.

51. The method of claim 37, the step of positioning each bunk assembly on the rigging table comprises positioning each bunk assembly on rails extending along the generally longitudinal axis, a plurality of guide wheels attached to the frames of the bunk assemblies movable along the rails.

52. The method of claim 37 comprising providing a camber in the assembled truss by engaging at least a portion of the frame of the bunk assemblies against stops adjacent a lateral extent of the base.

53 . The method of claim 52 where the stops include longitudinally extending camber rails having an longitudinal face adjacent a lateral extent of the base, the longitudinal face having a desired radius of curvature defining the camber.

54. The method of claim 37 comprising providing a zero camber in the assembled truss by engaging at least a portion of the frame of the bunk assemblies against stops adjacent a first lateral extent of the base or a standard camber in the assembled truss by engaging at least a portion of the frame of the bunk assemblies against stops adjacent a second lateral extent of the base.

55. The method of claim 37 comprising:
conveying chord portions, selected for a given truss to be assembled, into position under the bunk assemblies adjacent the lateral extent of the frames thereof; and engaging a chord portion positioned under the bunk assemblies and moving the chord portion to enable positioning the chord portion relative to the frame and guides for assembly of a truss.

56. The method of claim 55 comprising moving a worker guard panel to enable the chord portion to move from beneath the bunk assemblies to above the bunk assemblies for positioning for assembly of a truss, and returning the panel to its starting position.