CA1332559C - Apparatus and method for fabricating wood trusses - Google Patents
Apparatus and method for fabricating wood trussesInfo
- Publication number
- CA1332559C CA1332559C CA 611086 CA611086A CA1332559C CA 1332559 C CA1332559 C CA 1332559C CA 611086 CA611086 CA 611086 CA 611086 A CA611086 A CA 611086A CA 1332559 C CA1332559 C CA 1332559C
- Authority
- CA
- Canada
- Prior art keywords
- truss
- camber
- members
- rollers
- arm member
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27F—DOVETAILED WORK; TENONS; SLOTTING MACHINES FOR WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES
- B27F7/00—Nailing or stapling; Nailed or stapled work
- B27F7/15—Machines for driving in nail- plates and spiked fittings
- B27F7/155—Machines for driving in nail- plates and spiked fittings for nail plates
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27H—BENDING WOOD OR SIMILAR MATERIAL; COOPERAGE; MAKING WHEELS FROM WOOD OR SIMILAR MATERIAL
- B27H1/00—Bending wood stock, e.g. boards
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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Forests & Forestry (AREA)
- Wood Science & Technology (AREA)
Abstract
Abstract Apparatus and Method for Fabricating Wood Trusses An apparatus and method for fabricating wood trusses.
The truss members and connector plates are assembled on a conveyor surface, which transports the truss members to a first pressing station where the connector plates are partially embedded into the truss members and then to a second pressing station where camber is imparted to the truss and the connector plates are substantially completely embedded into the truss. The pressing rollers have substantially the same diameter and are sufficiently large to prevent the connector plates from rocking back and forth during the initial stages of the pressing operation. Three elongated guide rails are disposed beneath the conveyor surface to prevent the sagging thereof under the weight of the truss. The two outer guide rails extend all the way through the first pressing station to keep the conveyor surface in proper alignment. Camber is imparted to the truss in the second pressing station by means of two sets of oppositely positioned camber rollers. The first pair of camber rollers is mounted on a pivot arm for contacting the top chord of the truss and the second pair of camber rollers is adjustable by a single adjustment mechanism, laterally with respect to the axis movement of the truss, for contacting the bottom chord of the truss. An adjustable stabilizer bolt contacts the pivot arm to prevent free play therein during the cambering operation. In an alternate embodiment camber is imparted to the truss on the conveyor surface before the connector plates are attached by placing the truss members between a plurality of tooling blocks disposed at predetermined fixed positions on the conveyor surface in accordance with the truss dimensions and desired amount of camber.
The truss members and connector plates are assembled on a conveyor surface, which transports the truss members to a first pressing station where the connector plates are partially embedded into the truss members and then to a second pressing station where camber is imparted to the truss and the connector plates are substantially completely embedded into the truss. The pressing rollers have substantially the same diameter and are sufficiently large to prevent the connector plates from rocking back and forth during the initial stages of the pressing operation. Three elongated guide rails are disposed beneath the conveyor surface to prevent the sagging thereof under the weight of the truss. The two outer guide rails extend all the way through the first pressing station to keep the conveyor surface in proper alignment. Camber is imparted to the truss in the second pressing station by means of two sets of oppositely positioned camber rollers. The first pair of camber rollers is mounted on a pivot arm for contacting the top chord of the truss and the second pair of camber rollers is adjustable by a single adjustment mechanism, laterally with respect to the axis movement of the truss, for contacting the bottom chord of the truss. An adjustable stabilizer bolt contacts the pivot arm to prevent free play therein during the cambering operation. In an alternate embodiment camber is imparted to the truss on the conveyor surface before the connector plates are attached by placing the truss members between a plurality of tooling blocks disposed at predetermined fixed positions on the conveyor surface in accordance with the truss dimensions and desired amount of camber.
Description
Description Apparatus_and Method for Fabricatin~ Wood Trusses Technical Field The present invention relates generally to wood trusses used in building construction and in particular to an apparatus and method for fabricating wood trusses.
Back~round Art According to prior practice, wood trusses msy be 10 fabricated by placing the top and bottom chords in position on a movable support surface, such as a truss assembly ~ig, and by attaching the vertical connector members and web members between the chords with corrugated fasteners or nails to hold the vertical connector members and web members in 15 position. Stop members are typically positioned in contact with the top and bottom chords along the respectlve outer surfaces thereof to hold the truss members securely in position on the moveable surface of the jig.
A first set of connector plates is placed over the 20 joints at which the verticsl connector members and web members intersect the top and bottom chord~ on the upwardly facing ~urface of the truss and tapped so that the teeth of the connector plates are slightly imbedded into the wood to hold them in place. A lifting device is then used to raise 25 the truss from the support surface sufficiently to place a second set of connector plates under the truss on the ~oints on the downwardly facing surface of the truss at substantially the same locstions as on the upwardly facing surface thereof. At this stage, connector plates are 30 positioned on the trus3 joints on both the upwardly and downwardly facing surfaces thereof, with the second set of connector plates positioned between the downwardly facing surface of the truss and the moveable support surf2ce.
The truss is then carried by the support surface into 35 one or more pressing stations, which are compris-ed of one or more pairs of pressing rollers, whereby the connector plates are embedded into the wooden members at the truss joints as ~""~ '' ' } i: , , .. . .
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the truss is passed between each pair of rollers. Camber is typically imparted to the truss by a plurality of camber rollers positioned downstream of the first pressing station.
Apparatus and methods known in the art for fabricating 5 wood trusses have several disadvantages and limitations. One problem associated with such prior art apparatus and methods i9 that the first pair of pre~sing rollers typically has a substantially smaller diameter than the sets of pressing rollers located downstream. The first pair of pressing 10 rollers is used to partially embed the teeth of the connector plates into the wood members of the truss. The relatively abrupt curvature of the roller surface, as compared to the larger diameter rollers located downstream, may impart a rocking motion to the connector plates, which prevents the 15 teeth from being pressed straight into the wood members.
Another problem associated with such prior art truss assembly apparatus and methods is the problem of controlling the amount of camber applied to the truss. It is often difficult to produce a consistent, predetermined camber 20 because of the difficulty in properly positioning the camber rollers and in maintaining the camber rollers in position.
The mechanism used to position the camber rollers is subjected to large mechanical stresses when the truss is being cambered, which msy result in slippage and free play ; 25 in the camber roller positioning mechanism. S t i 1 1 another problem associated with prior srt apparatus and methods of fabricating trusses is the problem of maintaining the truss in proper alignment as the truss passes through the various stages of pres~ing rollers and through the camber 30 rollers. In order to securely attach the connector plates, the truss must be moved from the support surface of the jig before the trus~ enters the final pressing station.
Misalignment of the truss as it passes through the final pressing station causes critical errors in the fabrication 35 of the truss.
Disclosure of Invention It is therefore the principal object of the present .
invention to provide sn approved apparatus and method for ~ fabricating wood trusses.
It is another object of the invention to provide an improved apparatus and method for imparting camber to a wood 5 truss.
It is still another object of the invention to provide an apparatu3 and method for enhancing the precision and consistency of the camber imparted to a wood truss.
It i9 yet another object of the invention to provide an 10 improved apparatus and method for attaching metal connector plates to the joints of a wooden truss.
A further object of the invention is to provide an improved apparatus for maintaining the truss sub~tantially in proper alignment during the fabrication of the truss.
These and other objects are accomplished in accordance with the present invention wherein an apparatus and method for fabricating truss members into a completed truss is provided. The truss members are comprised of a plurality of wood members and a plurality of metal connector plates for 20 ~oining the wood members. The apparatus includes a relatively flat conveyor surface for supporting the tru~s members with the connector plates positioned below and on top of the wood member; means for moving the conveyor surface with the truss members supported thereon in a predetermined 25 direction; a first pressing station having at least one pair of pressing rollers disposed substantially in registration for receiving the truss members therebetween to partially embed the connector plates into the wood members; and a second pressing station spaced from the firqt pressing 30 station and beyond the conveyor surface. The second pressing station has a pair of pressing rollers disposed substantially in registration for receiving the truss members therebetween to substantially fully embed the connector plates into the wood members to complete fabrication of the truss.
In accordance with one aspect of the invention, the pressing rollers of the second pressing station have substantially the same size as the pressing rollers of the ~",.,,,",",, "
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first pres~ing station. In one embodiment 811 of the pressing rollers have a substantially cylindrical shape and the diameter of all of the pressing rollers is as large as practicable in accordance with the spatial constraints of 5 the apparatus. In the preferred embodiment esch of the pressing rollers has a diameter of at least ten inches. The use of relatively large diameter pressing rollers in both the first and second pressing stations has the advantage of pressing the connector plates into the wood members 10 straighter than when smaller diameter rollers are used because larger diameter roller~ impart substantially less rocking action on the front and back ends of the connector plates than do the smaller diameter rollers.
In accordance with another aspect of the invention, the 15 apparatus includes a plurality of elongated guide rails extending along the predetermlned direction of movement of the truss beneath the conveyor surface for supporting the conveyor surface and the tru~s members. At least one of the . - -.
guide rails extends beyond the first pressing station to 20 maintain the alignment of the conveyor surface. In one embodiment the plurality of guide rails is comprised of a central guide rail and two outer guide rails. The two outer guide rails extend beyond the first pressing station to maintain conveyor surface alignment. The conveyor surface 25 preferably includes a plurality of cooperating pairs of guide rollers positioned on an underside thereof for contacting respective opposite side~ of one of the outer guide rails to maintain conveyor surface alignment. In another embodiment the plurality of guide rails is comprised of two outer guide 30 rails positioned adjacent to respective opposite edges of the conveyor surface and two inside guide rails disposed between the two outer guide rails. The two outer guide rails extend beyond the first pressing station to maintain the conveyor surface alignment. When four guide rails are used, the 35 conveyor surface has a plurality of cooperating palrs of guide rollers disposed on an underside thereof. The guide rollers of each cooperating pair contact the respective outer j" ,-1 3~2559 surfaces of the two outside guide rails to maintain the conveyor surface in alignment.
In yet another aspect of the invention, a lifting roller is disposed between the first and second pressing stations 5 for engaging an underside of a leading portion of the truss for maintaining the vertical position of the truss as the truss is moved between the first and second pressing stations.
In accordance with a further aspect of the invention, 10 the apparatus includes means for selectively imparting camber to the truss. Switch means i5 positioned between the first pressing station and the camber means for disabling the operation of the apparatus when the switch means is activated by contact with the truss. The switch means is positioned 15 90 that the truss will only contact the switch means when the truss is improperly aligned with respect to the camber means.
In one embodiment the switch means includes a projection member which is positioned to contact the truss when the truss i9 out of alignment. In another embodiment the 20 position of the switch means is adjustable along an axis which is transverse with respect to the predetermined direction of movement of the truss to conform to the width of the truss as measured along the transverse axis. In yet another embodiment the camber means is comprised of first, 25 second, third and fourth camber rollers. The first and second camber rollers contact the top chord and the third and fourth camber rollers contact the bottom chord of the trus~
to apply a bending moment thereto. The third and fourth camber rollers are adjustable along the transverse axi~ to 30 conform to the width of the truss. The switch means is mechanically coupled to the third camber roller so that the position of the switch means is adjustable along the transverse axis together with the third camber roller.
In accordance with yet another aspect of the invention, 35 the first and second camber rollers are mounted on a first surface of an arm member, which is pivotally mounted adjacent to a first side of the apparatus and beyond the conveyor .'' .'"., ' '' ' ~
~ 332559 surface and the third and fourth camber rollers are positioned adjacent to a second side of the apparatus, opposite from the first side thereof. The first and second camber rollers are out of alignment with respect to an axis S which is parallel to the predetermined direction of movement of the truss when the arm member i9 pivoted from a first position at which the arm member is substantially parallel to the predetermined direction. The amount of displacement of the arm member from the first position determines the 10 amount of camber imparted to the truss. Ad~ustment means i9 provided for ~electively pivoting the arm member to position the arm membe~ to impart the predetermined amount of camber and engagement means is provided for preventing the arm member from pivoting back toward the first position after the 15 arm member has been pivoted away from the first position, thereby counteracting torque exerted on the arm member by the truss tending to bend the arm member back toward the first position. In the preferred embodiment, the engagement mean~ is comprised of a threadedimember, one end of which 20 engages a second surface of the arm member, which is opposite from the first ~urface thereof on which the fir~t and second camber rollers are mounted. The rotation of the threaded member in a first direction moves the threaded member toward the second surface of the arm member to engage the arm member 25 and prevent it from being moved back toward the first position. The rotation of the threaded member in a second direction, opposite from the first direction, moves the threaded member away from the second surface of the arm member to allow the arm member to be moved back toward the 30 first position.
In accordance with still another aspect of the invention the third and fourth camber rollers are maintained substantially in alignment along an axis which i~ parallel to the predetermined direction of movement of the truss.
35 Means for adJusting the position of the third and fourth camber rollers laterally with respect to the predetermined direction of the truss i~ provided so that the thlrd and 1 3325~9 fourth camber rollers are movable substantially in unison in ~ each direction alGng the lateral axis. In one embodiment the adjustment means i3 comprised of first and second spaced apart vertical arms, each of which has a threaded sleeve at 5 each end thereof. The third camber roller i9 mounted on the first verticsl arm and the second camber roller is mounted on the second vertical arm. First and second cooperating pairs of threaded shaft~ extend laterally with respect to the predetermined direction of movement of the truss. The 10 individual shafts in the first cooperating pair extend through corresponding sleeves on the first vertical arm so that the ~haft threads en8age complementary threads in the corresponding sleeves. The individual shafts in the second cooperating pair extend through corresponding sleeves on the 15 second vertical arm 90 that the shaft threads engage complementary threads in the corresponding sleeves. Means for rotating the first and second cooperating pairs of shafts in unison is provided ~o that the engagement between the shaft threads and the sleeve threads results in movement of 20 the first and second vertical arms and the corresponding third and fourth camber rollers laterall~ along the corresponding shafts.
In accordance with a further sspect of the invention, the apparatus includes drive means for moving the conveyor 25 surface with the truss members supported thereon in a predetermined direction. The drive means is comprised of first and second chain and sprocket drives in ~paced parallel relationship. Each of the chain and sprocket drives has first and second end sprockets with a drive chain disposed 30 on the end sprockets to define a continuous loop drive. The first end sprocket of the ~irst chain and sprocket drive is substantially aligned with the corresponding first end sprocket of the second chain and sprocket drive along a first axis extending laterally with respect to the predetermined 35 direction and the second end sprocket of the first chain and sprocket drive is substantially aligned with the corresponding second end sprocket of the second chain and ..~ .
,,,, j. ~ . . :
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1 332~9 sprocket drive along a second axis extending laterally with respect to the predetermined direction. A first plurality of elongated members extends laterally with respect to the predetermined direction for connecting the corresponding 5 first end sprockets and a second plurality of elongated members extends laterally with respect to the predetermined direction for connecting the corresponding ~econd end sprockets. The elongated members are substantislly rigid for maintaining the corresponding first end sprockets in lO substantially parallel relationship and the corresponding second end sprockets in substantially parallel relationship.
In yet another aspect of the invention camber is imparted to the truss by providing a relatively flat surface for supporting the wood members of the truss; mounting first 15 and second sets of restraining members at selected fixed positions on the support surface 90 that the restraining members define a boundary corresponding to the desired configuration of the truss to be cambered; and placing the wood members on the support surface within the boundary 20 defined by the restraining members 90 that the connector plate~ are disposed below and on top of the wood members.
Web members are connected to the top and bottom chords to urge the chords into contact with corre~ponding ones of the restraining members 90 that an outwardly facing surface of 25 the top chord contacts respective inwardly facing surfaces of the first set of restraining members and an outwardly facing surface of the bottom chord contacts respective lnwardly facing surfaces of the second set of restraining members, so that the restraining members exert a bending 30 moment on the top and bottom chords to impart camber to the truss.
In the preferred embodiment the support surface is comprised of a plurality of elongated slats oriented trsnsversely with respect to the major axis of the support 35 ~urface. Selected ones of the slats have a plurality of openings spaced at predetermined intervals along the respective major axes of the corresponding slats.
_9_ Corresponding openings of ad~acent ones of the slats are offset relative to one another along the respective major axes of the corresponding slats 80 that imaginary line segments connecting the corresponding openings define a curve 5 representing the desired amount of camber to be imparted to the truss. The restraining members have respective base portions with a plurality of holes extending therethrough.
Selected ones of the holes are positioned in regi~tration with ~elected ones of the openings in the corresponding slats 10 for mounting the restraining members thereon. In accordance with the present invention camber is imparted to the truss prior to the attachment of the metal connector plates, which facilitates the cambering operating, particularly when heavy duty trusses are bein8 fabricated for commercial 15 applications.
Brief Descri~tion of the DrawinRs Further ob~ect3 and advantages of the invention will be apparent from the detailed description and claims when read in conjunction with the accompanying drawings wherein:
FIGURE 1 is a perspective view of an apparatus for fabricating a wood truss in accordance with the present invention;
FIGURE 2 is a top plan view of the apparatus of FIGURE
1, emphasizing selected portions of the Apparatus;
FIGURE 3A is a side elevation view of a first embodiment of the apparatus according to the present invention;
FIGURE 3B is a side elevation view of a portion of a second embodiment of the apparatus;
FIGURE 4 is an end elevation view of the apparatus 30 according to the present invention, viewed from the discharge or downstream end of the apparatus;
FIGURE 5 is a side elevation view of a portion of the apparatus, illustrating means for lifting the truss as it passes through the pressing ststion~ in the apparatu~;
FIGURE 6 is a top plan, partial cu~away view, illustrating the mechanism by which selected ones of the camber rollers are positioned to impart predetermined camber -~
r ~ .-.,, -` 1 3~2559 to the truss;
FIGURE 7 is a side elevation view, illustrating the positioning of a cut-off switch for stopping the operation of the apparatus when the truss is out of alignment; ~ ~ -FIGURE 8 is an end elevation view, illustrating three guide rails beneath the movable support surPace of the apparatus;
FIGURE 9 is a top plan view of the table sectlon of the apparatus on which the truss members are disposed, 10 illustrating the means by which camber is imparted to the truss prior to the attachment of the metal connector plates;
~ IGURE 10 is a top plan view detailing a portion of the apparatus and truss depicted in FIGURE 9;
FIGURE 11 is a perspective view of a portion of a chain 15 and sprocket drive system for the apparatus; and FIGURE 12 is a circuit diagram illustrating means for selectively enabling and disabling the apparatus; and FIGU~E 13 is an end elevation view, illustrating three chain drives and four guide rails beneath the moveable 20 support surface of the apparatus.
Best Mode for CarrYin~ Out the Invention In the description which follows like parts are marked throughout the specification and drawings, re~pectively.
The drawings are not necessarily to scale and in some 25 instances proportionq have been exaggerated in order to ~ore clearly depict certain features of the invention.
Referring to FIGURES 1, 2, 3A and 4, an apparatus 10 for -~
fabricating wood trusses in accordance with the present invention is comprised of a table section 12 and a head 30 section 14. Table section 12 includes a motor-driven -` i conveyor, which is preferably comprised of a pair of parallel, continuous loop chain and sprocket drives 16A and 16B, which are attached to the respective undersurfaces of a plurality of parallel steel slats 18, which define conveyor 35 surface 19 of table section 12. Selected ones of slats 18 have a plurality of pre-drilled threaded holes (not shown) therein for positioning a plurality of tooling blocks (as ,, ~ ~ : :.
will be described in greater detail hereinafter with reference to FIGURE 9) on the corre9ponding top surface5 thereof for anchoring the chord9 of the truss while the web members and vertical connector members are placed 5 therebetween. The actual placement of the tooling blocks is adjusted to fit the dimensions of the truss being assembled.
Head section 14 has a first pressing station with first and second pairs of press rollers 20 and 22, respectively, for partially embedding the connector plates into the truss lO members as the truss passes between each pair of rollers 20 and 22. Roller pairs 20 and 22 are comprised of respective top roll,ers 20A and 22A and bottom rollers 20B and 22B for exerting a pressing force in a direction which is substantially perpendicular to the plane of movable conveyor 15 surface 19. Top rollers 20A and 22A are independently adjustable along a vertical axis to adjust the spacing between each top roller 20A and 22A and its corresponding bottom roller 20B and 22B to conform to the thickness of the truss being fabricated. The vertical adjustment of top 20 rollers 20A and 22A is accomplished in a conventional manner, such as by means of a screw-operated adjustment mechanism, as described in U. S. Patent No. 3,667,379.
A second pressing station, located downstream of the first pressing station, includes a third pair of rollers 24, which is comprised of a corresponding top roller 24A and bottom roller 24B for completing the attachment of the connector plates to the truss members after the predetermined camber has been applied to the truss. The connector plates must be embedded into the truss by first and second sets of rollers 20 and 22 sufficiently to ensure that the plates are not dislodged during the cambering operation and yet not so much as to prevent the camber rollers from imparting the desired amount of camber to the truss. Camber is applied to the truss by means of four camber rollers 26, 28, 30 and 32.
Camber rollers 26 and 28 engage the top chord of the truss and camber rollers 30 and 32 engage the bottom chord of the ., ~. - , , ,' ', , ~
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1 3~2559 truss. The operation of the camber rollers will be described in greater detail hereinafter.
In one aspect of the invention, rollers 20A and 20B, 22A
and 22B, and 24A and 24B all have substantially the same 5 diameter. The sequential action by which the plates are embedded into the truss members is controlled by the vertical adjustment of the three top roller~ 20A, 22A and 24A with respect to their corresponding bottom rollers 20B, 22B and 24B, as previously described. The diameter of each of these 10 rollers is preferably as large as possible within the spatial constraints of head section 14. The larger diameter rollers tend to press the connector plates into the truss members much straighter than when smaller diameter rollers are used because of the more gradual curvature of the surface of the 15 larger diameter rollers, which reduces the rocking action on the upstream and downstream ends of the connector plates.
A roller diameter on the order of 10 inches is usually sdequate.
Referrin8 to FIGURE 3B, an alternate embodiment of an 20 apparatus 11 for fabricating wood trusses has three pairs of rollers 21, 23 and 25 in the flrst pressing station instead of two pairs. A fourth pair of rollers 27 is positioned in the second pressing station. All of the rollers comprising first, second, third and fourth pairs of rollers preferably 25 have substantially the same diameter. The use of three pairs of rollers instead of two in the fir~t pressing station is advantageous when large, heavy duty trusses for commercial buildings are being fabricated because of the larger truss members and connector plates used, which reguire 8reater 30 pressing forces to embed the connector plates.
Referring again to FIGURES 1, 2, 3A and 4, all three pairs of press rollers 20, 22 and 24 are driven by means of a common chain and sprocket drive arrangement 29, as best seen in FIGURE 1, which is slaved to chain and sprocket 35 drives 16A and 16B 90 that the press rollers are synchronously driven in connection with movable conveyor surface 19. The motive apparatus for the chain and sprocket .~ , ~ . , .
drives assoclated with movable conveyor surface 19 and roller sets 20, 22 and 24 is provided by an electric motor 34, which turns the aforementioned chain and ~procket drives through a reduction gear 36. An air clutch 38 i8 interposed between 5 motor 34 and reduction gear 36 to provide a smooth startup for apparatus 10 so the connector plates positioned between the truss and the top surface of slats 18 do not 91ip during start up.
Referring also to FIGURE 8, each slat 18 i9 attached to 10 drive chains 40A and 40B compri~ing chain and sprocket drives 16A and 16B at respective opposite ends of each slat. Three elongated guide rails 42A, 42B and 42C are disposed beneath slats 18 for maintainin8 the alignment of slats 18 along a predetermined downstream direction when appsratus 10 is being 15 operated so as to move the truss members along table section 12 and into head section 14 in proper position. Selected ones of slats 18 have a pair of guide rollers 44 positioned on an undersurface thereof for contacting respective opposite sides of outer guide rail 42A to keep each slat 18 in proper alignment. Each guide rail 42A, 42B and 42C has a low friction material 43 disposed thereon to facilitate the sliding actlon of slats 18 along guide rail~ 42A, 42B and 42C. Low friction material 43 is preferably comprised of UHMW (ultra-high molecular weight) polyethylene material.
In another aspect of the invention center guide rail 42C
is added to outside rails 42A and 42B to better support slats 18 and the truss members being carried thereon. The addition of center guide rail 42C prevents sagging at the center of movable conveyor surface 19, which can lead to deformation 30 of the truss and improper positioning thereof as the truss enters head section 14. In another embodiment, as shown in FIGURE 13, four guide rails 42D, 42E, 42F and 42G are provided for supporting conveyor surface 19, ~uch that there are two outside rails and two inside rails. A guide roller 35 44 i9 positioned in contact with the outside surface of each - of the two outside rails to guide the slats along the rails.
Three chaln and drive mechani~m~ 16C, 16D and 16E are , ~ ~
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posltioned as shown in FIGURE 13, with guide rails 42D and 42E positioned between chain and drive mechanisms 16C and 16D
and guide rails 42F and 42G positioned between chain and drive mechanisms 16D and 16E, to increase the driving force 5 imparted to the conveyor. This configuration i9 well-suited for the fabrication of hea~y duty trusses for commercial application.
In yet another aspect of the invention, as best seen in FIGURES 2 and 5, outer guide rails 42A and 42B are extended 10 beyond the first pressing station in head 3ection 14 in order to maintain con~eyor surface l9 in proper alignment as the connector plates are being partially embedded into the truss members in head section 14. As best seen in FIGURE 5, outer guide rails 42A and 42B extend to a posltion which is 15 substantially coterminous with drive shaft 48 at the downstream end of chain and sprocket drives 16A and 16B, although only guide rail 42A and chain and sprocket drive 16A
are depicted in FIGURE 5. It i8 at this location that chain and sprocket drive 16A and, of course, chain and sprocket ~0 drive 16B on the opposite side, make a U-turn at the downstresm end of the continuous loop chain and sprocket drives. An elongated roller 50 is positioned at the inlet to the second pressing station and beneath camber roller~ 26 and ~ -~
30 for lifting truss 52 upwardly 90 that the truss 52 clears 25 lower press roller 24B as truss 52 continues its downstream 1 movement. Lifting roller 50 preferably spans substantially the entire width of apparatus 10. -~
Referring to FIGURES 2 and 7, an electrical cut-off switch 54 is posltioned downstream of chain and ~procket 30 drives 16A and 16B at the inlet to the second pressing station. Switch 54 is mounted on an elongated bar 56, which is in turn attached to an arm 58 on which camber roller 30 is mounted. Arm 58 has a pair of threaded sleeves 60 disposed at respective opposite ends thereof for engaging 35 complementary threads on a pair of parallel shafts 62, which extend laterally with respect to the direction of movement of truss 52. Camber roller 32 i8 mounted in substantlally , ~ : . .. : , -`~:
the same manner on arm 64, which engages a corresponding pair of parallel shafts 66.
Camber rollers 30 and 32 are positioned in contact with the bottom chord of tru~s 52. The position of camber rollers 5 30 and 32 is ad~usted laterally with respect to the axis of movement of truqs 52 to conform to the width dimensions of the truss being fabricated. As camber roller 30 i~ moved laterally, cu~-off switch 54 i9 also moved laterally ~o that the position of cut-off switch 54 is adjusted in accordance 10 with the width of truss 52. If truss 52 is out of alignment as it moves pa~t the down~tream end of conveyor surface 19, truss 52 will contact switch 54, which automatically disables motor 34 and air clutch 38 and stops the operation of apparatus 10, as shown in FIGURE 12. Motor 34 must be 15 restarted and then air clutch 38 before apparatus 10 can be reactivated. An emergency stop cable extends around the perimeter of the entire apparatus 10 and associated machinery to disable motor 34 and air clutch 38 when the cable is pulled. Apparatus lO cannot be reactivated until motor 34 20 is fir~t restarted and then air clutch 38.
Referring also to FIGURE 3A, a limit switch 55 is mounted on frame 57 for engaging a projection 59 mounted on a particular slat 18 to temporarily disable apparatus 10 when switch 55 is open. Switch 55 is normally in a closed 25 position, but is open when pro~ection 59 engages switch 55.
Pro~ection 59 includes a cam member, which engages a cam roller attached to switch 55 to open switch 55. As shown in FIGURE 12, air clutch 38, but not motor 34, is disabled when switch 55 is open. In this manner apparatus 10 is 30 temporarily disabled after each truss fabrication cycle to allow the operators to position the truss components on conveyor surface 19 for the next fabrication cycle. Thus, apparatus 10 will be started from and stopped at substantially the same position for each cycle. Keeping 35 motor 34 running decreases the time required be~tween cycles by eliminating the delays assoc~ated with motor ~tart-up.
Referring specifically to FIGURES 2, 3A and 4, camber , ~ ,-- ,-, .
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rollers 30 and 32 are movable laterally with respect with the axis of movement of truss 52 by means of a common adjustment device. Each pair of threaded shafts 62 and 66 i8 mechanically slaved together by means of a common chain and 5 sprocket mechanism 61, as best qeen in FIGURES 2 and 3A.
Chain and sprocket mechanism 61 is operated by means of a handle 68. The direction in which handle 68 is turned determines the direction of rotation of chain and sprocket mechanism 61, which in turn determines the direction of lO rotation of threaded shafts 62 and 66, thereby causing arms 58 and 64 and their respective camber rollers 30 and 32 to move in the desired direction laterally with respect to the axis of movement of truss 52. In this manner camber rollers 30 and 32, which contact the bottom chord of truss 52, are 15 ad~usted together in a single step operation, which facilitates the adjustment process and enhances the positioning accuracy of camber rollers 30 and 32.
Referring to FIGURES 2 and 6, camber rollers 26 and 28, which contact the top chord of truss 52, are mounted on a 20 pi~ot arm 70 which pivots about a vertical axis passing through a position indicated at 72. A crank handle 74 i9 turned to ad~ust the position of pivot arm 70. The more that camber roller 28 is moved out of alignment with camber roller 26, the greater will be the camber imparted to truss 52. To 25 prevent slippage of pivot arm 70, which can result in errors in the truss camber, and to mechanically strengthen pivot arm 70 and hold it in a fixed position, a stabilizer bolt 76 is positioned in contact with back surface 70A of pivot arm 70, which is opposite from front surface 70B of pivot arm 70 on 30 which camber rollers 26 and 28 are mounted. Bolt 76 is adjusted snug again~t back surface 70A of pivot arm 70 to counteract the torque which tends to bend pivot arm 70 away from truss 52 when camber is being imparted thereto. A nut 77 holds bolt 76 in position in housing 79, which has aligned 35 threaded openings for receiving bolt 76 and engaging complementary threads on bolt 76.
Referring to FIGURE 9, an alternate embodiment for Zf Z'~
1 33~559 imparting camber to truss 52 i9 depicted. As previously mentioned, selected one of slats 18 have a plurallty of pre-drilled threaded holes 75 at selected positions along corresponding ~lats 18 for receiving corre~ponding tooling 5 blocks 78, which are used to hold the truss members in position during the fabrication process. Holes 75 are po~itioned at intervals of approximately one and one-half inches along the corresponding slats 18. Individual slats 18 having holes 75 are arranged at approximately two foot 10 intervals along the axis of movement of conveyor surface 19.
Each tooling block 78 has a series of holes on the base portion thereof at intervals of approximately three-fourths of an inch. Each block 78 is affixed to a corresponding slat 18 by positioning two of the holes in block 78 in 15 registration with a selected pair of holes 75 on the corresponding slat 18 and by bolting block 78 to the corresponding slat 18. The positions of blocks 78 may be ad~usted in increments of approximately one-half inch.
Tooling blocks 78 are positioned to define the desired lines 20 along which truss 52 is to be cambered. Top chord 52A, bottom chord 52B, web members 52C and vertical members 52D
are forced into position between fixed blocks 78 to form the outline of truss 52. Connector plates 80 are positioned over the truss ~oints both above and below truss 52, as previously 25 described. At this ~uncture, connector plates 80 have not yet been embedded into the truss joints 90 that less force is required to impart camber to trus~ 52 than when camber rollers are used in the second pressing station after connector plates 80 have been partially embedded into truss 30 52. Tooling blocks 78 hold the truss members in position to maintain the desired amount of camber as truss 52 is moved through the first and second pressing stations in which connector plates 80 are fully embedded into trusg 52, thereby eliminating the need for camber rollers in the second 35 pressing station.
Referring to FIGURE 10, holes 75 on each slat 18 are preferably offset slightly, along an axis which i9 trangver9e 1 33~55~
relative to the movement of conveyor surface 19, with respect to the corresponding holes 75 on ad~acent slats 18 so that imaginary line segments connecting corresponding holes 18 on adjacent Qlats 18 approximate a curve representing the 5 desired amount of camber of truss 52. Holes 75 are pre-drilled to specifications depending upon the desired camber.
For example, if the desired amount of camber is such that the center of each trus~ chord i9 displaced approximately three-fourths of an inch from an axis connecting the ends of the 10 truss for each 40 foot span of truss (a radius of curvature of approximately 3,200 feet), holes 75 are predrilled 90 that the top and bottom chords will be bent to define that approximate arc when the chords are positioned between tooling blocks 78. FIGURE 10 illustrates the central portion 15 of bottom chord 52B, which is bent by tooling blocks 78 to impart the desired amount of camber. Although not shown in FIGURE 10, the top chord is also cambered the same amount as bottom chord 52B by corresponding tooling blocks positioned to define the desired camber arc. It is easier to impart the 20 camber before the connector plates are embedded, particularly when heavy duty trusses, which may be comprised of 4x4 or even larger chords, are being fabricated. Blocks 78 are mounted in the corresponding holes 75 in accordance with the width of the truss (i.e., the distance between the respective 25 outer surfaces of the top and bottom chords).
Referring to FIGURE 11, four elongated rigid bars 82 are attached at their respective opposite ends to the facing ma~or surfaces of sprockets 84A and 84B at both ends of chain and sprocket drives 16A and 16B in order to stabilize 30 sprockets 84A and 84B and prevent the sprockets from wobbling during operation. Although only the downstream ends of chain and sprocket drives 16A and 16B are shown, one skilled in the art will appreciate that the two sprockets at the upstream ends of drives 16A and 16B also have four stabilizer bars 82 35 extending therebetween. Bars 82 are disposed at substantially equal angular intervals around central drive shaft 48 connecting sprockets 84A and 84B.
. Various embodiments of the invention have now been described in detail. Since it iq obvious that changeq in and sdditions to the above-described preferred embodiment msy be made without departing from the nature, spirit and scope of .
5 the invention, the invention is not to be limited to said details, except as ~et forth in the sppended claims.
, . ,. :.. , , .s.,. - .... ,. :: . . : ::,,:: , : .: .: . , . - . : . .. . ~ .
Back~round Art According to prior practice, wood trusses msy be 10 fabricated by placing the top and bottom chords in position on a movable support surface, such as a truss assembly ~ig, and by attaching the vertical connector members and web members between the chords with corrugated fasteners or nails to hold the vertical connector members and web members in 15 position. Stop members are typically positioned in contact with the top and bottom chords along the respectlve outer surfaces thereof to hold the truss members securely in position on the moveable surface of the jig.
A first set of connector plates is placed over the 20 joints at which the verticsl connector members and web members intersect the top and bottom chord~ on the upwardly facing ~urface of the truss and tapped so that the teeth of the connector plates are slightly imbedded into the wood to hold them in place. A lifting device is then used to raise 25 the truss from the support surface sufficiently to place a second set of connector plates under the truss on the ~oints on the downwardly facing surface of the truss at substantially the same locstions as on the upwardly facing surface thereof. At this stage, connector plates are 30 positioned on the trus3 joints on both the upwardly and downwardly facing surfaces thereof, with the second set of connector plates positioned between the downwardly facing surface of the truss and the moveable support surf2ce.
The truss is then carried by the support surface into 35 one or more pressing stations, which are compris-ed of one or more pairs of pressing rollers, whereby the connector plates are embedded into the wooden members at the truss joints as ~""~ '' ' } i: , , .. . .
,,,, :. : . - , ..
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the truss is passed between each pair of rollers. Camber is typically imparted to the truss by a plurality of camber rollers positioned downstream of the first pressing station.
Apparatus and methods known in the art for fabricating 5 wood trusses have several disadvantages and limitations. One problem associated with such prior art apparatus and methods i9 that the first pair of pre~sing rollers typically has a substantially smaller diameter than the sets of pressing rollers located downstream. The first pair of pressing 10 rollers is used to partially embed the teeth of the connector plates into the wood members of the truss. The relatively abrupt curvature of the roller surface, as compared to the larger diameter rollers located downstream, may impart a rocking motion to the connector plates, which prevents the 15 teeth from being pressed straight into the wood members.
Another problem associated with such prior art truss assembly apparatus and methods is the problem of controlling the amount of camber applied to the truss. It is often difficult to produce a consistent, predetermined camber 20 because of the difficulty in properly positioning the camber rollers and in maintaining the camber rollers in position.
The mechanism used to position the camber rollers is subjected to large mechanical stresses when the truss is being cambered, which msy result in slippage and free play ; 25 in the camber roller positioning mechanism. S t i 1 1 another problem associated with prior srt apparatus and methods of fabricating trusses is the problem of maintaining the truss in proper alignment as the truss passes through the various stages of pres~ing rollers and through the camber 30 rollers. In order to securely attach the connector plates, the truss must be moved from the support surface of the jig before the trus~ enters the final pressing station.
Misalignment of the truss as it passes through the final pressing station causes critical errors in the fabrication 35 of the truss.
Disclosure of Invention It is therefore the principal object of the present .
invention to provide sn approved apparatus and method for ~ fabricating wood trusses.
It is another object of the invention to provide an improved apparatus and method for imparting camber to a wood 5 truss.
It is still another object of the invention to provide an apparatu3 and method for enhancing the precision and consistency of the camber imparted to a wood truss.
It i9 yet another object of the invention to provide an 10 improved apparatus and method for attaching metal connector plates to the joints of a wooden truss.
A further object of the invention is to provide an improved apparatus for maintaining the truss sub~tantially in proper alignment during the fabrication of the truss.
These and other objects are accomplished in accordance with the present invention wherein an apparatus and method for fabricating truss members into a completed truss is provided. The truss members are comprised of a plurality of wood members and a plurality of metal connector plates for 20 ~oining the wood members. The apparatus includes a relatively flat conveyor surface for supporting the tru~s members with the connector plates positioned below and on top of the wood member; means for moving the conveyor surface with the truss members supported thereon in a predetermined 25 direction; a first pressing station having at least one pair of pressing rollers disposed substantially in registration for receiving the truss members therebetween to partially embed the connector plates into the wood members; and a second pressing station spaced from the firqt pressing 30 station and beyond the conveyor surface. The second pressing station has a pair of pressing rollers disposed substantially in registration for receiving the truss members therebetween to substantially fully embed the connector plates into the wood members to complete fabrication of the truss.
In accordance with one aspect of the invention, the pressing rollers of the second pressing station have substantially the same size as the pressing rollers of the ~",.,,,",",, "
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p~
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first pres~ing station. In one embodiment 811 of the pressing rollers have a substantially cylindrical shape and the diameter of all of the pressing rollers is as large as practicable in accordance with the spatial constraints of 5 the apparatus. In the preferred embodiment esch of the pressing rollers has a diameter of at least ten inches. The use of relatively large diameter pressing rollers in both the first and second pressing stations has the advantage of pressing the connector plates into the wood members 10 straighter than when smaller diameter rollers are used because larger diameter roller~ impart substantially less rocking action on the front and back ends of the connector plates than do the smaller diameter rollers.
In accordance with another aspect of the invention, the 15 apparatus includes a plurality of elongated guide rails extending along the predetermlned direction of movement of the truss beneath the conveyor surface for supporting the conveyor surface and the tru~s members. At least one of the . - -.
guide rails extends beyond the first pressing station to 20 maintain the alignment of the conveyor surface. In one embodiment the plurality of guide rails is comprised of a central guide rail and two outer guide rails. The two outer guide rails extend beyond the first pressing station to maintain conveyor surface alignment. The conveyor surface 25 preferably includes a plurality of cooperating pairs of guide rollers positioned on an underside thereof for contacting respective opposite side~ of one of the outer guide rails to maintain conveyor surface alignment. In another embodiment the plurality of guide rails is comprised of two outer guide 30 rails positioned adjacent to respective opposite edges of the conveyor surface and two inside guide rails disposed between the two outer guide rails. The two outer guide rails extend beyond the first pressing station to maintain the conveyor surface alignment. When four guide rails are used, the 35 conveyor surface has a plurality of cooperating palrs of guide rollers disposed on an underside thereof. The guide rollers of each cooperating pair contact the respective outer j" ,-1 3~2559 surfaces of the two outside guide rails to maintain the conveyor surface in alignment.
In yet another aspect of the invention, a lifting roller is disposed between the first and second pressing stations 5 for engaging an underside of a leading portion of the truss for maintaining the vertical position of the truss as the truss is moved between the first and second pressing stations.
In accordance with a further aspect of the invention, 10 the apparatus includes means for selectively imparting camber to the truss. Switch means i5 positioned between the first pressing station and the camber means for disabling the operation of the apparatus when the switch means is activated by contact with the truss. The switch means is positioned 15 90 that the truss will only contact the switch means when the truss is improperly aligned with respect to the camber means.
In one embodiment the switch means includes a projection member which is positioned to contact the truss when the truss i9 out of alignment. In another embodiment the 20 position of the switch means is adjustable along an axis which is transverse with respect to the predetermined direction of movement of the truss to conform to the width of the truss as measured along the transverse axis. In yet another embodiment the camber means is comprised of first, 25 second, third and fourth camber rollers. The first and second camber rollers contact the top chord and the third and fourth camber rollers contact the bottom chord of the trus~
to apply a bending moment thereto. The third and fourth camber rollers are adjustable along the transverse axi~ to 30 conform to the width of the truss. The switch means is mechanically coupled to the third camber roller so that the position of the switch means is adjustable along the transverse axis together with the third camber roller.
In accordance with yet another aspect of the invention, 35 the first and second camber rollers are mounted on a first surface of an arm member, which is pivotally mounted adjacent to a first side of the apparatus and beyond the conveyor .'' .'"., ' '' ' ~
~ 332559 surface and the third and fourth camber rollers are positioned adjacent to a second side of the apparatus, opposite from the first side thereof. The first and second camber rollers are out of alignment with respect to an axis S which is parallel to the predetermined direction of movement of the truss when the arm member i9 pivoted from a first position at which the arm member is substantially parallel to the predetermined direction. The amount of displacement of the arm member from the first position determines the 10 amount of camber imparted to the truss. Ad~ustment means i9 provided for ~electively pivoting the arm member to position the arm membe~ to impart the predetermined amount of camber and engagement means is provided for preventing the arm member from pivoting back toward the first position after the 15 arm member has been pivoted away from the first position, thereby counteracting torque exerted on the arm member by the truss tending to bend the arm member back toward the first position. In the preferred embodiment, the engagement mean~ is comprised of a threadedimember, one end of which 20 engages a second surface of the arm member, which is opposite from the first ~urface thereof on which the fir~t and second camber rollers are mounted. The rotation of the threaded member in a first direction moves the threaded member toward the second surface of the arm member to engage the arm member 25 and prevent it from being moved back toward the first position. The rotation of the threaded member in a second direction, opposite from the first direction, moves the threaded member away from the second surface of the arm member to allow the arm member to be moved back toward the 30 first position.
In accordance with still another aspect of the invention the third and fourth camber rollers are maintained substantially in alignment along an axis which i~ parallel to the predetermined direction of movement of the truss.
35 Means for adJusting the position of the third and fourth camber rollers laterally with respect to the predetermined direction of the truss i~ provided so that the thlrd and 1 3325~9 fourth camber rollers are movable substantially in unison in ~ each direction alGng the lateral axis. In one embodiment the adjustment means i3 comprised of first and second spaced apart vertical arms, each of which has a threaded sleeve at 5 each end thereof. The third camber roller i9 mounted on the first verticsl arm and the second camber roller is mounted on the second vertical arm. First and second cooperating pairs of threaded shaft~ extend laterally with respect to the predetermined direction of movement of the truss. The 10 individual shafts in the first cooperating pair extend through corresponding sleeves on the first vertical arm so that the ~haft threads en8age complementary threads in the corresponding sleeves. The individual shafts in the second cooperating pair extend through corresponding sleeves on the 15 second vertical arm 90 that the shaft threads engage complementary threads in the corresponding sleeves. Means for rotating the first and second cooperating pairs of shafts in unison is provided ~o that the engagement between the shaft threads and the sleeve threads results in movement of 20 the first and second vertical arms and the corresponding third and fourth camber rollers laterall~ along the corresponding shafts.
In accordance with a further sspect of the invention, the apparatus includes drive means for moving the conveyor 25 surface with the truss members supported thereon in a predetermined direction. The drive means is comprised of first and second chain and sprocket drives in ~paced parallel relationship. Each of the chain and sprocket drives has first and second end sprockets with a drive chain disposed 30 on the end sprockets to define a continuous loop drive. The first end sprocket of the ~irst chain and sprocket drive is substantially aligned with the corresponding first end sprocket of the second chain and sprocket drive along a first axis extending laterally with respect to the predetermined 35 direction and the second end sprocket of the first chain and sprocket drive is substantially aligned with the corresponding second end sprocket of the second chain and ..~ .
,,,, j. ~ . . :
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,. .. .
1 332~9 sprocket drive along a second axis extending laterally with respect to the predetermined direction. A first plurality of elongated members extends laterally with respect to the predetermined direction for connecting the corresponding 5 first end sprockets and a second plurality of elongated members extends laterally with respect to the predetermined direction for connecting the corresponding ~econd end sprockets. The elongated members are substantislly rigid for maintaining the corresponding first end sprockets in lO substantially parallel relationship and the corresponding second end sprockets in substantially parallel relationship.
In yet another aspect of the invention camber is imparted to the truss by providing a relatively flat surface for supporting the wood members of the truss; mounting first 15 and second sets of restraining members at selected fixed positions on the support surface 90 that the restraining members define a boundary corresponding to the desired configuration of the truss to be cambered; and placing the wood members on the support surface within the boundary 20 defined by the restraining members 90 that the connector plate~ are disposed below and on top of the wood members.
Web members are connected to the top and bottom chords to urge the chords into contact with corre~ponding ones of the restraining members 90 that an outwardly facing surface of 25 the top chord contacts respective inwardly facing surfaces of the first set of restraining members and an outwardly facing surface of the bottom chord contacts respective lnwardly facing surfaces of the second set of restraining members, so that the restraining members exert a bending 30 moment on the top and bottom chords to impart camber to the truss.
In the preferred embodiment the support surface is comprised of a plurality of elongated slats oriented trsnsversely with respect to the major axis of the support 35 ~urface. Selected ones of the slats have a plurality of openings spaced at predetermined intervals along the respective major axes of the corresponding slats.
_9_ Corresponding openings of ad~acent ones of the slats are offset relative to one another along the respective major axes of the corresponding slats 80 that imaginary line segments connecting the corresponding openings define a curve 5 representing the desired amount of camber to be imparted to the truss. The restraining members have respective base portions with a plurality of holes extending therethrough.
Selected ones of the holes are positioned in regi~tration with ~elected ones of the openings in the corresponding slats 10 for mounting the restraining members thereon. In accordance with the present invention camber is imparted to the truss prior to the attachment of the metal connector plates, which facilitates the cambering operating, particularly when heavy duty trusses are bein8 fabricated for commercial 15 applications.
Brief Descri~tion of the DrawinRs Further ob~ect3 and advantages of the invention will be apparent from the detailed description and claims when read in conjunction with the accompanying drawings wherein:
FIGURE 1 is a perspective view of an apparatus for fabricating a wood truss in accordance with the present invention;
FIGURE 2 is a top plan view of the apparatus of FIGURE
1, emphasizing selected portions of the Apparatus;
FIGURE 3A is a side elevation view of a first embodiment of the apparatus according to the present invention;
FIGURE 3B is a side elevation view of a portion of a second embodiment of the apparatus;
FIGURE 4 is an end elevation view of the apparatus 30 according to the present invention, viewed from the discharge or downstream end of the apparatus;
FIGURE 5 is a side elevation view of a portion of the apparatus, illustrating means for lifting the truss as it passes through the pressing ststion~ in the apparatu~;
FIGURE 6 is a top plan, partial cu~away view, illustrating the mechanism by which selected ones of the camber rollers are positioned to impart predetermined camber -~
r ~ .-.,, -` 1 3~2559 to the truss;
FIGURE 7 is a side elevation view, illustrating the positioning of a cut-off switch for stopping the operation of the apparatus when the truss is out of alignment; ~ ~ -FIGURE 8 is an end elevation view, illustrating three guide rails beneath the movable support surPace of the apparatus;
FIGURE 9 is a top plan view of the table sectlon of the apparatus on which the truss members are disposed, 10 illustrating the means by which camber is imparted to the truss prior to the attachment of the metal connector plates;
~ IGURE 10 is a top plan view detailing a portion of the apparatus and truss depicted in FIGURE 9;
FIGURE 11 is a perspective view of a portion of a chain 15 and sprocket drive system for the apparatus; and FIGURE 12 is a circuit diagram illustrating means for selectively enabling and disabling the apparatus; and FIGU~E 13 is an end elevation view, illustrating three chain drives and four guide rails beneath the moveable 20 support surface of the apparatus.
Best Mode for CarrYin~ Out the Invention In the description which follows like parts are marked throughout the specification and drawings, re~pectively.
The drawings are not necessarily to scale and in some 25 instances proportionq have been exaggerated in order to ~ore clearly depict certain features of the invention.
Referring to FIGURES 1, 2, 3A and 4, an apparatus 10 for -~
fabricating wood trusses in accordance with the present invention is comprised of a table section 12 and a head 30 section 14. Table section 12 includes a motor-driven -` i conveyor, which is preferably comprised of a pair of parallel, continuous loop chain and sprocket drives 16A and 16B, which are attached to the respective undersurfaces of a plurality of parallel steel slats 18, which define conveyor 35 surface 19 of table section 12. Selected ones of slats 18 have a plurality of pre-drilled threaded holes (not shown) therein for positioning a plurality of tooling blocks (as ,, ~ ~ : :.
will be described in greater detail hereinafter with reference to FIGURE 9) on the corre9ponding top surface5 thereof for anchoring the chord9 of the truss while the web members and vertical connector members are placed 5 therebetween. The actual placement of the tooling blocks is adjusted to fit the dimensions of the truss being assembled.
Head section 14 has a first pressing station with first and second pairs of press rollers 20 and 22, respectively, for partially embedding the connector plates into the truss lO members as the truss passes between each pair of rollers 20 and 22. Roller pairs 20 and 22 are comprised of respective top roll,ers 20A and 22A and bottom rollers 20B and 22B for exerting a pressing force in a direction which is substantially perpendicular to the plane of movable conveyor 15 surface 19. Top rollers 20A and 22A are independently adjustable along a vertical axis to adjust the spacing between each top roller 20A and 22A and its corresponding bottom roller 20B and 22B to conform to the thickness of the truss being fabricated. The vertical adjustment of top 20 rollers 20A and 22A is accomplished in a conventional manner, such as by means of a screw-operated adjustment mechanism, as described in U. S. Patent No. 3,667,379.
A second pressing station, located downstream of the first pressing station, includes a third pair of rollers 24, which is comprised of a corresponding top roller 24A and bottom roller 24B for completing the attachment of the connector plates to the truss members after the predetermined camber has been applied to the truss. The connector plates must be embedded into the truss by first and second sets of rollers 20 and 22 sufficiently to ensure that the plates are not dislodged during the cambering operation and yet not so much as to prevent the camber rollers from imparting the desired amount of camber to the truss. Camber is applied to the truss by means of four camber rollers 26, 28, 30 and 32.
Camber rollers 26 and 28 engage the top chord of the truss and camber rollers 30 and 32 engage the bottom chord of the ., ~. - , , ,' ', , ~
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1 3~2559 truss. The operation of the camber rollers will be described in greater detail hereinafter.
In one aspect of the invention, rollers 20A and 20B, 22A
and 22B, and 24A and 24B all have substantially the same 5 diameter. The sequential action by which the plates are embedded into the truss members is controlled by the vertical adjustment of the three top roller~ 20A, 22A and 24A with respect to their corresponding bottom rollers 20B, 22B and 24B, as previously described. The diameter of each of these 10 rollers is preferably as large as possible within the spatial constraints of head section 14. The larger diameter rollers tend to press the connector plates into the truss members much straighter than when smaller diameter rollers are used because of the more gradual curvature of the surface of the 15 larger diameter rollers, which reduces the rocking action on the upstream and downstream ends of the connector plates.
A roller diameter on the order of 10 inches is usually sdequate.
Referrin8 to FIGURE 3B, an alternate embodiment of an 20 apparatus 11 for fabricating wood trusses has three pairs of rollers 21, 23 and 25 in the flrst pressing station instead of two pairs. A fourth pair of rollers 27 is positioned in the second pressing station. All of the rollers comprising first, second, third and fourth pairs of rollers preferably 25 have substantially the same diameter. The use of three pairs of rollers instead of two in the fir~t pressing station is advantageous when large, heavy duty trusses for commercial buildings are being fabricated because of the larger truss members and connector plates used, which reguire 8reater 30 pressing forces to embed the connector plates.
Referring again to FIGURES 1, 2, 3A and 4, all three pairs of press rollers 20, 22 and 24 are driven by means of a common chain and sprocket drive arrangement 29, as best seen in FIGURE 1, which is slaved to chain and sprocket 35 drives 16A and 16B 90 that the press rollers are synchronously driven in connection with movable conveyor surface 19. The motive apparatus for the chain and sprocket .~ , ~ . , .
drives assoclated with movable conveyor surface 19 and roller sets 20, 22 and 24 is provided by an electric motor 34, which turns the aforementioned chain and ~procket drives through a reduction gear 36. An air clutch 38 i8 interposed between 5 motor 34 and reduction gear 36 to provide a smooth startup for apparatus 10 so the connector plates positioned between the truss and the top surface of slats 18 do not 91ip during start up.
Referring also to FIGURE 8, each slat 18 i9 attached to 10 drive chains 40A and 40B compri~ing chain and sprocket drives 16A and 16B at respective opposite ends of each slat. Three elongated guide rails 42A, 42B and 42C are disposed beneath slats 18 for maintainin8 the alignment of slats 18 along a predetermined downstream direction when appsratus 10 is being 15 operated so as to move the truss members along table section 12 and into head section 14 in proper position. Selected ones of slats 18 have a pair of guide rollers 44 positioned on an undersurface thereof for contacting respective opposite sides of outer guide rail 42A to keep each slat 18 in proper alignment. Each guide rail 42A, 42B and 42C has a low friction material 43 disposed thereon to facilitate the sliding actlon of slats 18 along guide rail~ 42A, 42B and 42C. Low friction material 43 is preferably comprised of UHMW (ultra-high molecular weight) polyethylene material.
In another aspect of the invention center guide rail 42C
is added to outside rails 42A and 42B to better support slats 18 and the truss members being carried thereon. The addition of center guide rail 42C prevents sagging at the center of movable conveyor surface 19, which can lead to deformation 30 of the truss and improper positioning thereof as the truss enters head section 14. In another embodiment, as shown in FIGURE 13, four guide rails 42D, 42E, 42F and 42G are provided for supporting conveyor surface 19, ~uch that there are two outside rails and two inside rails. A guide roller 35 44 i9 positioned in contact with the outside surface of each - of the two outside rails to guide the slats along the rails.
Three chaln and drive mechani~m~ 16C, 16D and 16E are , ~ ~
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posltioned as shown in FIGURE 13, with guide rails 42D and 42E positioned between chain and drive mechanisms 16C and 16D
and guide rails 42F and 42G positioned between chain and drive mechanisms 16D and 16E, to increase the driving force 5 imparted to the conveyor. This configuration i9 well-suited for the fabrication of hea~y duty trusses for commercial application.
In yet another aspect of the invention, as best seen in FIGURES 2 and 5, outer guide rails 42A and 42B are extended 10 beyond the first pressing station in head 3ection 14 in order to maintain con~eyor surface l9 in proper alignment as the connector plates are being partially embedded into the truss members in head section 14. As best seen in FIGURE 5, outer guide rails 42A and 42B extend to a posltion which is 15 substantially coterminous with drive shaft 48 at the downstream end of chain and sprocket drives 16A and 16B, although only guide rail 42A and chain and sprocket drive 16A
are depicted in FIGURE 5. It i8 at this location that chain and sprocket drive 16A and, of course, chain and sprocket ~0 drive 16B on the opposite side, make a U-turn at the downstresm end of the continuous loop chain and sprocket drives. An elongated roller 50 is positioned at the inlet to the second pressing station and beneath camber roller~ 26 and ~ -~
30 for lifting truss 52 upwardly 90 that the truss 52 clears 25 lower press roller 24B as truss 52 continues its downstream 1 movement. Lifting roller 50 preferably spans substantially the entire width of apparatus 10. -~
Referring to FIGURES 2 and 7, an electrical cut-off switch 54 is posltioned downstream of chain and ~procket 30 drives 16A and 16B at the inlet to the second pressing station. Switch 54 is mounted on an elongated bar 56, which is in turn attached to an arm 58 on which camber roller 30 is mounted. Arm 58 has a pair of threaded sleeves 60 disposed at respective opposite ends thereof for engaging 35 complementary threads on a pair of parallel shafts 62, which extend laterally with respect to the direction of movement of truss 52. Camber roller 32 i8 mounted in substantlally , ~ : . .. : , -`~:
the same manner on arm 64, which engages a corresponding pair of parallel shafts 66.
Camber rollers 30 and 32 are positioned in contact with the bottom chord of tru~s 52. The position of camber rollers 5 30 and 32 is ad~usted laterally with respect to the axis of movement of truqs 52 to conform to the width dimensions of the truss being fabricated. As camber roller 30 i~ moved laterally, cu~-off switch 54 i9 also moved laterally ~o that the position of cut-off switch 54 is adjusted in accordance 10 with the width of truss 52. If truss 52 is out of alignment as it moves pa~t the down~tream end of conveyor surface 19, truss 52 will contact switch 54, which automatically disables motor 34 and air clutch 38 and stops the operation of apparatus 10, as shown in FIGURE 12. Motor 34 must be 15 restarted and then air clutch 38 before apparatus 10 can be reactivated. An emergency stop cable extends around the perimeter of the entire apparatus 10 and associated machinery to disable motor 34 and air clutch 38 when the cable is pulled. Apparatus lO cannot be reactivated until motor 34 20 is fir~t restarted and then air clutch 38.
Referring also to FIGURE 3A, a limit switch 55 is mounted on frame 57 for engaging a projection 59 mounted on a particular slat 18 to temporarily disable apparatus 10 when switch 55 is open. Switch 55 is normally in a closed 25 position, but is open when pro~ection 59 engages switch 55.
Pro~ection 59 includes a cam member, which engages a cam roller attached to switch 55 to open switch 55. As shown in FIGURE 12, air clutch 38, but not motor 34, is disabled when switch 55 is open. In this manner apparatus 10 is 30 temporarily disabled after each truss fabrication cycle to allow the operators to position the truss components on conveyor surface 19 for the next fabrication cycle. Thus, apparatus 10 will be started from and stopped at substantially the same position for each cycle. Keeping 35 motor 34 running decreases the time required be~tween cycles by eliminating the delays assoc~ated with motor ~tart-up.
Referring specifically to FIGURES 2, 3A and 4, camber , ~ ,-- ,-, .
- .: - , -. -:, " , ';: ' ' '~ ' , , ,, ; , .; .
rollers 30 and 32 are movable laterally with respect with the axis of movement of truss 52 by means of a common adjustment device. Each pair of threaded shafts 62 and 66 i8 mechanically slaved together by means of a common chain and 5 sprocket mechanism 61, as best qeen in FIGURES 2 and 3A.
Chain and sprocket mechanism 61 is operated by means of a handle 68. The direction in which handle 68 is turned determines the direction of rotation of chain and sprocket mechanism 61, which in turn determines the direction of lO rotation of threaded shafts 62 and 66, thereby causing arms 58 and 64 and their respective camber rollers 30 and 32 to move in the desired direction laterally with respect to the axis of movement of truss 52. In this manner camber rollers 30 and 32, which contact the bottom chord of truss 52, are 15 ad~usted together in a single step operation, which facilitates the adjustment process and enhances the positioning accuracy of camber rollers 30 and 32.
Referring to FIGURES 2 and 6, camber rollers 26 and 28, which contact the top chord of truss 52, are mounted on a 20 pi~ot arm 70 which pivots about a vertical axis passing through a position indicated at 72. A crank handle 74 i9 turned to ad~ust the position of pivot arm 70. The more that camber roller 28 is moved out of alignment with camber roller 26, the greater will be the camber imparted to truss 52. To 25 prevent slippage of pivot arm 70, which can result in errors in the truss camber, and to mechanically strengthen pivot arm 70 and hold it in a fixed position, a stabilizer bolt 76 is positioned in contact with back surface 70A of pivot arm 70, which is opposite from front surface 70B of pivot arm 70 on 30 which camber rollers 26 and 28 are mounted. Bolt 76 is adjusted snug again~t back surface 70A of pivot arm 70 to counteract the torque which tends to bend pivot arm 70 away from truss 52 when camber is being imparted thereto. A nut 77 holds bolt 76 in position in housing 79, which has aligned 35 threaded openings for receiving bolt 76 and engaging complementary threads on bolt 76.
Referring to FIGURE 9, an alternate embodiment for Zf Z'~
1 33~559 imparting camber to truss 52 i9 depicted. As previously mentioned, selected one of slats 18 have a plurallty of pre-drilled threaded holes 75 at selected positions along corresponding ~lats 18 for receiving corre~ponding tooling 5 blocks 78, which are used to hold the truss members in position during the fabrication process. Holes 75 are po~itioned at intervals of approximately one and one-half inches along the corresponding slats 18. Individual slats 18 having holes 75 are arranged at approximately two foot 10 intervals along the axis of movement of conveyor surface 19.
Each tooling block 78 has a series of holes on the base portion thereof at intervals of approximately three-fourths of an inch. Each block 78 is affixed to a corresponding slat 18 by positioning two of the holes in block 78 in 15 registration with a selected pair of holes 75 on the corresponding slat 18 and by bolting block 78 to the corresponding slat 18. The positions of blocks 78 may be ad~usted in increments of approximately one-half inch.
Tooling blocks 78 are positioned to define the desired lines 20 along which truss 52 is to be cambered. Top chord 52A, bottom chord 52B, web members 52C and vertical members 52D
are forced into position between fixed blocks 78 to form the outline of truss 52. Connector plates 80 are positioned over the truss ~oints both above and below truss 52, as previously 25 described. At this ~uncture, connector plates 80 have not yet been embedded into the truss joints 90 that less force is required to impart camber to trus~ 52 than when camber rollers are used in the second pressing station after connector plates 80 have been partially embedded into truss 30 52. Tooling blocks 78 hold the truss members in position to maintain the desired amount of camber as truss 52 is moved through the first and second pressing stations in which connector plates 80 are fully embedded into trusg 52, thereby eliminating the need for camber rollers in the second 35 pressing station.
Referring to FIGURE 10, holes 75 on each slat 18 are preferably offset slightly, along an axis which i9 trangver9e 1 33~55~
relative to the movement of conveyor surface 19, with respect to the corresponding holes 75 on ad~acent slats 18 so that imaginary line segments connecting corresponding holes 18 on adjacent Qlats 18 approximate a curve representing the 5 desired amount of camber of truss 52. Holes 75 are pre-drilled to specifications depending upon the desired camber.
For example, if the desired amount of camber is such that the center of each trus~ chord i9 displaced approximately three-fourths of an inch from an axis connecting the ends of the 10 truss for each 40 foot span of truss (a radius of curvature of approximately 3,200 feet), holes 75 are predrilled 90 that the top and bottom chords will be bent to define that approximate arc when the chords are positioned between tooling blocks 78. FIGURE 10 illustrates the central portion 15 of bottom chord 52B, which is bent by tooling blocks 78 to impart the desired amount of camber. Although not shown in FIGURE 10, the top chord is also cambered the same amount as bottom chord 52B by corresponding tooling blocks positioned to define the desired camber arc. It is easier to impart the 20 camber before the connector plates are embedded, particularly when heavy duty trusses, which may be comprised of 4x4 or even larger chords, are being fabricated. Blocks 78 are mounted in the corresponding holes 75 in accordance with the width of the truss (i.e., the distance between the respective 25 outer surfaces of the top and bottom chords).
Referring to FIGURE 11, four elongated rigid bars 82 are attached at their respective opposite ends to the facing ma~or surfaces of sprockets 84A and 84B at both ends of chain and sprocket drives 16A and 16B in order to stabilize 30 sprockets 84A and 84B and prevent the sprockets from wobbling during operation. Although only the downstream ends of chain and sprocket drives 16A and 16B are shown, one skilled in the art will appreciate that the two sprockets at the upstream ends of drives 16A and 16B also have four stabilizer bars 82 35 extending therebetween. Bars 82 are disposed at substantially equal angular intervals around central drive shaft 48 connecting sprockets 84A and 84B.
. Various embodiments of the invention have now been described in detail. Since it iq obvious that changeq in and sdditions to the above-described preferred embodiment msy be made without departing from the nature, spirit and scope of .
5 the invention, the invention is not to be limited to said details, except as ~et forth in the sppended claims.
, . ,. :.. , , .s.,. - .... ,. :: . . : ::,,:: , : .: .: . , . - . : . .. . ~ .
Claims (11)
1. Apparatus for imparting a predetermined amount of camber to a wood truss, said truss being comprised of oppositely positioned top and bottom chords and a plurality of web members interconnecting the top and bottom chords, said apparatus comprising:
a relatively flat conveyor surface for supporting said truss;
means for moving said truss in a predetermined direction;
an arm member pivotally mounted adjacent to a first side of said apparatus and beyond said conveyor surface;
first and second spaced apart camber rollers mounted on a first surface of said arm member for contacting the top chord of the truss, said first and second camber rollers being out of alignment with respect to an axis which is parallel to the predetermined direction when said arm member is pivoted from a first position at which said arm member is substantially parallel to the predetermined direction;
third and fourth spaced apart camber rollers positioned adjacent to a second side of said apparatus, opposite from the first side thereof, for contacting the bottom chord of the truss, said third and fourth camber rollers being oriented among an axis which is substantially parallel to the predetermined direction, said third and fourth camber rollers for cooperating with said first and second camber rollers to impart the predetermined amount of camber to the truss, the amount of displacement of said arm member from said first position for determining the amount of camber imparted thereto;
adjustment means for selectively pivoting said arm member to position said arm member to impart the predetermined amount of camber to the truss; and means for engaging a second surface of said arm member, opposite from the first surface thereof, to prevent said arm member from pivoting back toward said first position after said arm member has been pivoted away from said first position, thereby counteracting torque exerted on said arm member by said truss tending to bend said arm member back toward said first position when camber is being imparted to said truss.
a relatively flat conveyor surface for supporting said truss;
means for moving said truss in a predetermined direction;
an arm member pivotally mounted adjacent to a first side of said apparatus and beyond said conveyor surface;
first and second spaced apart camber rollers mounted on a first surface of said arm member for contacting the top chord of the truss, said first and second camber rollers being out of alignment with respect to an axis which is parallel to the predetermined direction when said arm member is pivoted from a first position at which said arm member is substantially parallel to the predetermined direction;
third and fourth spaced apart camber rollers positioned adjacent to a second side of said apparatus, opposite from the first side thereof, for contacting the bottom chord of the truss, said third and fourth camber rollers being oriented among an axis which is substantially parallel to the predetermined direction, said third and fourth camber rollers for cooperating with said first and second camber rollers to impart the predetermined amount of camber to the truss, the amount of displacement of said arm member from said first position for determining the amount of camber imparted thereto;
adjustment means for selectively pivoting said arm member to position said arm member to impart the predetermined amount of camber to the truss; and means for engaging a second surface of said arm member, opposite from the first surface thereof, to prevent said arm member from pivoting back toward said first position after said arm member has been pivoted away from said first position, thereby counteracting torque exerted on said arm member by said truss tending to bend said arm member back toward said first position when camber is being imparted to said truss.
2. The apparatus according to claim 1 wherein said engagement means is comprised of a threaded member, one end of which engages the second surface of the arm member, the rotation of said threaded member in a first direction for moving said threaded member toward the second surface of said arm member to engage said second surface and prevent said arm member from being moved back toward said first position, the rotation of said threaded member in a second direction, opposite from said first direction, for moving said threaded member away from the second surface of said arm member to allow said arm member to be moved back toward said first position.
3. The apparatus according to claim 2 wherein said threaded member engages said arm member at an intermediate position along the length thereof, said adjustment means being positioned adjacent to a free end of said arm member for cooperating with said threaded member to stabilize said arm member in a predetermined fixed position.
4. The apparatus according to claim 3 wherein said third and fourth camber rollers are adjustable along an axis which is transverse with respect to the predetermined direction to conform to the width of the truss as measured along the transverse axis, said apparatus including means for coupling said third and fourth camber rollers so that said third and fourth camber rollers are adjustable substantially in unison.
5. Apparatus for imparting camber to a truss, said truss being comprised of oppositely positioned top and bottom chords and a plurality of web members interconnecting the chords, said apparatus comprising:
a conveyor surface for supporting said truss;
means for moving said conveyor surface in a predetermined direction;
an elongated member pivotally mounted adjacent to a first side of said apparatus and beyond said conveyor surface, said elongated member having first and second spaced apart camber rollers mounted thereon so that said first and second camber rollers can be positioned out of alignment with respect to an axis which is parallel to the predetermined direction, said first and second camber rollers for engaging the top chord of the truss;
third and fourth spaced apart camber rollers positioned adjacent to a second side of the apparatus, opposite from the first side thereof, for engaging the bottom chord of the truss, said third and fourth camber rollers for being maintained substantially in alignment along an axis which is parallel to the predetermined direction; and means for adjusting the position of the third and fourth camber rollers laterally with respect to the predetermined direction so that said third and fourth camber rollers are movable substantially in unison in each direction along said lateral axis.
a conveyor surface for supporting said truss;
means for moving said conveyor surface in a predetermined direction;
an elongated member pivotally mounted adjacent to a first side of said apparatus and beyond said conveyor surface, said elongated member having first and second spaced apart camber rollers mounted thereon so that said first and second camber rollers can be positioned out of alignment with respect to an axis which is parallel to the predetermined direction, said first and second camber rollers for engaging the top chord of the truss;
third and fourth spaced apart camber rollers positioned adjacent to a second side of the apparatus, opposite from the first side thereof, for engaging the bottom chord of the truss, said third and fourth camber rollers for being maintained substantially in alignment along an axis which is parallel to the predetermined direction; and means for adjusting the position of the third and fourth camber rollers laterally with respect to the predetermined direction so that said third and fourth camber rollers are movable substantially in unison in each direction along said lateral axis.
6. The apparatus according to claim 5 wherein said means for adjusting the position of the third and fourth camber rollers is comprised of:
first and second spaced apart vertical arms, each of said vertical arms having a threaded sleeve at each end thereof, said third camber roller being mounted on said first vertical arm and said fourth camber roller being mounted on said second vertical arm;
first and second cooperating pairs of threaded shafts extending laterally with respect of the predetermined direction, the individual shafts in the first cooperating pair extending through corresponding sleeves on the first vertical arm so that the shaft threads engage complimentary threads in the corresponding sleeves, the individual shafts in the second cooperating pair extending through corresponding sleeves on the second vertical arm so that the shaft threads engage complementary threads in the corresponding sleeves; and means for rotating the first and second cooperating pairs of shafts in unison so that the engagement between the shaft threads and the threads of the corresponding sleeves results in the movement of the first and second vertical arms and the corresponding third and fourth camber rollers laterally along the corresponding shafts, the direction of rotation of said shafts determining the direction of lateral movement of said first and second vertical arms and said third and fourth camber rollers.
first and second spaced apart vertical arms, each of said vertical arms having a threaded sleeve at each end thereof, said third camber roller being mounted on said first vertical arm and said fourth camber roller being mounted on said second vertical arm;
first and second cooperating pairs of threaded shafts extending laterally with respect of the predetermined direction, the individual shafts in the first cooperating pair extending through corresponding sleeves on the first vertical arm so that the shaft threads engage complimentary threads in the corresponding sleeves, the individual shafts in the second cooperating pair extending through corresponding sleeves on the second vertical arm so that the shaft threads engage complementary threads in the corresponding sleeves; and means for rotating the first and second cooperating pairs of shafts in unison so that the engagement between the shaft threads and the threads of the corresponding sleeves results in the movement of the first and second vertical arms and the corresponding third and fourth camber rollers laterally along the corresponding shafts, the direction of rotation of said shafts determining the direction of lateral movement of said first and second vertical arms and said third and fourth camber rollers.
7. The apparatus according to claim 6 wherein said means for rotating said shafts in unison is comprised of chain and sprocket means for mechanically coupling the first and second cooperating pairs of shafts and handle means for mechanically rotating said chain and sprocket means in a desired direction to rotate said cooperating pairs of shafts and adjust the position of said third and fourth camber rollers.
8. A method for imparting a predetermined amount of camber to a wood truss, which is comprised of a plurality of wood members and a plurality of metal connector plates for joining said wood members, said wood members including top and bottom chords and web members for interconnecting the top and bottom chords, said method comprising the steps of:
providing a relatively flat surface for supporting said wood members;
mounting first and second sets of restraining members at selected fixed positions on the support surface so that said restraining members define a boundary corresponding to the desired configuration of the truss to be cambered;
placing said wood members on said support surface within the boundary defined by said restraining members so that said connector plates are disposed below and on top of said wood members and connecting said web members to said top and bottom chords to urge said top and bottom chords into contact with corresponding ones of said restraining members so that an outwardly facing surface of said top chord contacts respective inwardly facing surfaces of the first set of restraining members and an outwardly facing surface of said bottom chord contacts respective inwardly facing surfaces of the second set of restraining members, said restraining members for exerting a bending moment on said top and bottom chords to impart the desired amount of camber to the truss.
providing a relatively flat surface for supporting said wood members;
mounting first and second sets of restraining members at selected fixed positions on the support surface so that said restraining members define a boundary corresponding to the desired configuration of the truss to be cambered;
placing said wood members on said support surface within the boundary defined by said restraining members so that said connector plates are disposed below and on top of said wood members and connecting said web members to said top and bottom chords to urge said top and bottom chords into contact with corresponding ones of said restraining members so that an outwardly facing surface of said top chord contacts respective inwardly facing surfaces of the first set of restraining members and an outwardly facing surface of said bottom chord contacts respective inwardly facing surfaces of the second set of restraining members, said restraining members for exerting a bending moment on said top and bottom chords to impart the desired amount of camber to the truss.
9. The method according to claim 8 including the steps of:
providing a support surface having a plurality of slats which are oriented transversely with respect to the major axis of said support surface, selected ones of said slats having a plurality of openings spaced at predetermined intervals along the respective major axes of the corresponding slats, corresponding openings of adjacent ones of said slats being offset relative to one another along the respective major axes of the corresponding slats so that imaginary line segments connecting said corresponding openings approximate a curve representing the desired amount of camber to be imparted to the truss; and providing said restraining members with respective base portions having a plurality of holes extending therethrough; and positioning said restraining members so that selected ones of said holes are in registration with selected ones of said openings in said slats and mounting said restraining members on said slats to anchor said restraining members in the selected fixed positions.
providing a support surface having a plurality of slats which are oriented transversely with respect to the major axis of said support surface, selected ones of said slats having a plurality of openings spaced at predetermined intervals along the respective major axes of the corresponding slats, corresponding openings of adjacent ones of said slats being offset relative to one another along the respective major axes of the corresponding slats so that imaginary line segments connecting said corresponding openings approximate a curve representing the desired amount of camber to be imparted to the truss; and providing said restraining members with respective base portions having a plurality of holes extending therethrough; and positioning said restraining members so that selected ones of said holes are in registration with selected ones of said openings in said slats and mounting said restraining members on said slats to anchor said restraining members in the selected fixed positions.
10. Apparatus for imparting camber to the truss members of a wood truss, said truss members being comprised of top and bottom wooden chords, a plurality of wooden web members and a plurality of metal connector plates, said apparatus comprising:
a relatively flat surface for supporting said truss members;
first and second sets of restraining members for being mounted at selected fixed positions on said support surface so that said restraining members define a boundary corresponding to the desired configuration of the truss to be cambered, said truss members for being positioned inside of the boundary defined by said restraining members with said connector plates disposed below and on top of said top and bottom chords and web members, said web members for connecting said top and bottom chords and for urging said top and bottom chords into contact with said restraining members so that an outwardly surface of said top chord contacts respective inwardly facing surfaces of the first set of restraining members and an outwardly facing surface of the bottom chord contacts respective inwardly facing surfaces of the second set of restraining members, said restraining members for exerting a bending moment on said truss members to impart the desired amount of camber thereto.
a relatively flat surface for supporting said truss members;
first and second sets of restraining members for being mounted at selected fixed positions on said support surface so that said restraining members define a boundary corresponding to the desired configuration of the truss to be cambered, said truss members for being positioned inside of the boundary defined by said restraining members with said connector plates disposed below and on top of said top and bottom chords and web members, said web members for connecting said top and bottom chords and for urging said top and bottom chords into contact with said restraining members so that an outwardly surface of said top chord contacts respective inwardly facing surfaces of the first set of restraining members and an outwardly facing surface of the bottom chord contacts respective inwardly facing surfaces of the second set of restraining members, said restraining members for exerting a bending moment on said truss members to impart the desired amount of camber thereto.
11. The apparatus according to claim 10 wherein said support surface is comprised of a plurality of elongated slats oriented transversely with respect to the major axis of said support surface, selected ones of said slats having a plurality of openings spaced at predetermined intervals along the respective major axes of the corresponding slats, corresponding openings of adjacent ones of said slats being offset relative to one another along the respective major axes of the corresponding lats so that imaginary line segments connecting said corresponding openings define a curve representing the desired amount of camber to be imparted to the truss, said restraining members having respective base portions with a plurality of holes extending therethrough, selected ones of said holes for being positioned in registration with selected ones of said openings in the corresponding slats for mounting said restraining members on the corresponding slats.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US24369888A | 1988-09-13 | 1988-09-13 | |
| US243,698 | 1988-09-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1332559C true CA1332559C (en) | 1994-10-18 |
Family
ID=22919762
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 611086 Expired - Fee Related CA1332559C (en) | 1988-09-13 | 1989-09-12 | Apparatus and method for fabricating wood trusses |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0388462A4 (en) |
| AU (1) | AU4303889A (en) |
| CA (1) | CA1332559C (en) |
| WO (1) | WO1990002650A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE539506C2 (en) | 2013-03-01 | 2017-10-03 | Nordiska Truss Ab | Device for positioning a plurality of supports on a rail |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3120172A (en) * | 1962-11-23 | 1964-02-04 | Kimberly Clark Co | Method of compressing stacks of creped paper tissues |
| US3212694A (en) * | 1962-11-26 | 1965-10-19 | Sanford Ind Inc | Apparatus for fabricating wooden structures |
| US3903583A (en) * | 1975-01-31 | 1975-09-09 | James D Adams | Cambering attachment for truss assembly jig |
| US4005520A (en) * | 1976-03-09 | 1977-02-01 | Sanford Arthur C | Frame structure fabricating system |
| US4154164A (en) * | 1978-04-24 | 1979-05-15 | Hammond Daniel B | Wooden truss fabricating jig |
| US4672006A (en) * | 1986-03-28 | 1987-06-09 | Mcgraw David W | Tree processing and wood products system |
-
1989
- 1989-09-11 EP EP19890910754 patent/EP0388462A4/en not_active Withdrawn
- 1989-09-11 AU AU43038/89A patent/AU4303889A/en not_active Abandoned
- 1989-09-11 WO PCT/US1989/003944 patent/WO1990002650A1/en not_active Application Discontinuation
- 1989-09-12 CA CA 611086 patent/CA1332559C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| WO1990002650A1 (en) | 1990-03-22 |
| EP0388462A4 (en) | 1992-06-10 |
| EP0388462A1 (en) | 1990-09-26 |
| AU4303889A (en) | 1990-04-02 |
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