US3100301A

US3100301A - Method and apparatus for prefabricating prestressed monoplanar trusses

Info

Publication number: US3100301A
Application number: US55446A
Authority: US
Inventors: William H Black
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-09-12
Filing date: 1960-09-12
Publication date: 1963-08-13
Anticipated expiration: 1980-08-13

Description

Aug. 13, 1963 w. H. BLACK 3, 00, 0

METHOD AND APPARATUS FOR PREFABRICATING PRESTRESSED MONOPLANAR TRUSSES 2 Sheets-Sheet 1 Filed Sept. 12, 1960 FIG. I

INVEN TOR. WILLIAM H. BLACK Aug. 13, 1963 w. H. BLACK 3,100,301

METHOD AND APPARATUS FOR PREFABRICATING PRESTRESSED MONOPLANAR TRUSSES Filed Sept. 12. 1960 2 Sheets-Sheet 2 FIG. 7

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88g I42 Z 0 ,-86 11 0 INVENTOR.

WILLIAM H. BLACK BY I Halo ATTORNEY Unite rates atent ddhdfidl Patented Aug. 13, 1953 fiice METHUD AND APPARATUS FQR PREFABRICAT- ENG PRESTRESSED MQNGPLANAR TRUSSES William H. Black, 468 Dublin Ave, Columbus 15, @nio Filed ept. 12, 1960, Ser. No. 55,446 8 Claims. (Cl. l zitl) This invention relates to a method and apparatus for fabricating roof trusses and more particularly to the production of prestressed monoplanar trusses.

With the increase in prefabrication of homes and other buildings, it has become the practice to prefabricate wood roof trusses by placing precut timbers in a jig and then securing the timbers at their joints by staplelike nail plates embedded in one or both sides of the joints. The nail plates comprise metal plates having naillike portions struck therefrom substantially at right angles, and which are embedded in the timbers in the manner of staples. These prior art trusses have lacked efliciency for many and varied reasons in that the trusses were not prestressed so that the nail plate joints were subject to undue stress after a roof was installed thereon, and they required an excessive amount of time and/or labor in the fabrication of the trusses. Moreover, the jigs were incapable of or extremely difficult to adjust for forming different sizes and/or types of trusses.

Having in mind the defects of the prior art methods and apparatus for fabricating roof trusses, it is the primary object of the present invention to provide a method and apparatus for forming prestressed monoplanar trusses with a minimum of time and labor.

it is another object of the invention to provide a method and apparatus for prefabricating prestressed monoplanar trusses of selected size and type.

it is a further object to the invention to provide a method and apparatus for prefabricating prestressed monoplanar trusses of selected size and type having simplicity, economy and efiiciency.

The novel features that are considered characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment when read in connection with the accompanying drawings, wherein like reference characters indicate like parts throughout the several figures and in which:

FIG. 1 is a plan view of a typical monoplanar truss of the peak type formed with nail plates, an alternative hip type truss being shown in phantom lines;

FIG. 2 is a diagrammatic plan view of a truss fabricating machine in accordance with the present invention;

FIG. 3 is an enlarged fragmentary sectional view of a nail plate driving mechanism incorporated at each joining station;

FIGS. 4, 7 and 9 are enlarged cross-sectional views taken on lines 4-4, 77 and 9-9, respectively, of FIG. 2;

FIGS. 5 and 6 are cross-sectional views taken on lines 55 and 66, respectively, of FIG. 4;

FIG. 8 is a cross-sectional view taken on line 88 of FIG. 7, and

FIG. 10 is a cross-sectional view taken on line lit-14 of FIG. 9.

Referring now to FIG. 1, a typical peaked or triangular roof truss comprises a straight horizontal bottom chord ill and two angularly disposed upper chords 12 with a plurality of intermediate braces or struts. In the form shown, the braces or struts include a central vertical strut l3 and two laterally disposed vertical struts 14 with diagonal struts extending from one end of the central strut 13 to the other ends of the lateral struts 14. Preferably, the

diagonal struts 15 extend from the juncture of the central strut 13 with the horizontal chord 11 to the juncture of the lateral struts 14 with the upper chords 12.

Other arrangements of the brace struts may be employed with suitable disposition of the joining stations, but the illustrated arrangement provides maximum strength in the truss with maximum simplicity in the apparatus employed. In accordance with the present invention, the end product is not limited to a standard peaked truss, but is capable of forming hipped trusses wherein each of the upper chords include two angularly disposed chord elements 12a and 1212, the central chord 13 being proportionally shortened. Each of the joints between the chords ll, 12, 12:: and/or 12b and struts 13, 1.4 and 15 are secured by nail plates 16 which are well known in the art, and per se form' no part of the present invention.

An apparatus in accordance with the present invention, as best shown in FIG. 2, may comprise a suitable base, bed or floor 18, conveniently comprising a level concrete slab, on which is mounted guide means such as a plurality of tracks 20. Centrally of the length of the guide tracks 2b is located a joining station 22 that may be movably mounted on the tracks, but preferably is fixedly mounted on the base 58 as by supports 24, FIG. 4.

Movably mounted on the guide tracks 29 are a plurality of intermediate joining stations 26, with at least one on each side of the central station 22, and a pair of end joining stations 28 respectively beyond the intermediate stations. For the simple type trusses shown in FIG. 1, there is only one intermediate station 26 on each side of the central station; but more intermediate stations may be included for fabricating extremely long or more complex trusses, such as double hipped trusses or the like.

Briefly, the central station 22 comprises a base 3%, see also FIG. 4, mounted on the supports 24 and on which is a fixed stanchion 32 and a movable stanchion 34 which is adjustable relative to the fixed stanchion 32 perpendicularly of the guide tracks 20. Similarly, the inter-' mediate stations 26 each comprise a base 36 movably mounted, as by rollers or wheels 33, on the guide tracks 20, see also FIG. 7, and which carries a fixed stanchion 40 and a movable stanchion 42 adjustable normal to the guide tracks 20 relative to the fixed stanchion as. Finally, the end stations 28 each comprise a base l i movably mounted, as by rollers or Wheels 46, on the guide tracks 20 and which supports a fixed stanchion 48 that itself movably carries a pressure member 50 adjustable normal to the guide tracks 20. I

The fixed

stanchions

32, 40 and 48 are disposed in alignment for operating on the horizontal base chord 11 of a truss, and the

movable stanehions

34, 42 and pressure member 5t are adjustable for operating on the top chords 12 of a truss. The intermediate and end stations 26 and '28 are adjustable along the guide tracks 2% for accommodating trusses of different sizes. The adjustable stations 25 and 23 may be moved manually along the guide tracks, or any suitable power meansmay be employed. For purposes of illustration, 2. motor 52 and reduction gear 54 may be mounted on the central base 3% for driving a pair of

screws

56, 58 which thread through nuts 6-9, 62 fixed on the

movable stations

26 and 28, respectively.

The screws 56, 53 and nuts 6%, 62 may be so designed as to move the

stations

26 and 28 in predetermined relation in accordance with truss size, or the screws may be independently driven through selectively operable clutches, in known manner. If more than one intermediate station is employed on each side, additional screws may be employed for moving such stations proportionally. The motor 52 may be driven by any suitable source of power such as fluid, electric or the-like, as the particular drive system forms no part of the present invention.

Each of the, stanchions 3-2, 34 4t), 42 and as is provided with timber supporting and nail plate driving mechanism, all of which are substantially identical, and one of which is shown in FIG. 3. The particular construction of the main body of each stanchion is immaterial except that it is preferred that the same be left open or be pro-. vided with some means of access for readily and easily placingthe lower nail plate. For this purpose, it is'convenient to construct'each stanchion generally in the man ner shown in FIG. 3. v

In this case, the stanchion presents opposite upstanding side Walls 64 which are joined along their upper edges by a top plate 66 and which may be otherwise joined and reinforced as desired, so long as the back provides an access opening as indicated at 68. Each side wall is notched or slotted asindicated by reference character 70 so that opposite side openings are presented to. permit the

chord timbers

11 or 12 to pass therethrough. Each such timber, which would be an upper or lower chord member as the case may be, is automatically positioned by engagement with, a. pressure plate 74 extending between the spaced side walls 64, such pressure plates being rigid with the side walls or othe-rwise'integrally joined to the body of the stanchion.

' Each chord, is supported on a table plate 76 rigid with the stanchion and which preferably projects outwardly therefrom to provide a convenient place upon which to rest the chord members initially before they are pushed back against the'pressure plates 74 through the forwardly facing slots, or notches 78 provided for by the side wall slots 70, the table 67, the portion of top wall 66 which overhangs the table 76 and the pressure plate 74. Additionally, each forward projection of the table plates provides a ready means for mounting one or a pair of guide posts. 80 serving to receive therebetween, and to thereby locate, one of the

vertical struts

13 or 14, as shown in FIGS. 3, 5, 6 and 8. Pr fera'bly, these posts 80 are a-djustably mounted to accommodate various size timbers, such as 2 x 4, 2 x 6 and the like, and for purposes of illustration, each post is" provided with a reduced oneof a'plurality of holes 86, see FIGS. 5, 6L and 8, to enable selective predetennined positioning of the posts. There are. two pairs of cooperative holes 86, one pair in -which the posts 80 are located and the uncovered pair which, when the posts are located therein, will accommodate a larger strut timber.

the nail plates 16. The rain plate 92 is movable through an opening 180 in table 76 and when in its lowered position, permits of easy placement of a nail plate 16 thereon through stanchion access opening 68.

V Preferably, this may be done before chord placement,

[and then when the chords and necessary'struts are subsequently placed, the upper nail plate may be positioned diameter pin portion 84, see FIG. 3, which is received in which rest upon the base '30 or 36, respectively, and permit of the aforesaid movement toward and away from their corresponding fixed stanchions 32 and 4%.

For effecting the controlled movement of the

stanchions

34 and 42, hydraulic cylinder and piston assemblies 120, 12-2 may be used. As shown in FIG. 4, the cylinder is rigid with base 30 and the piston 122 V in each case is fixed to a respective stanchion 34 or 42'.

Operating in conjunction with this movement of the stanchions are the pressure arms 50 on the end stanchions 48. Each pressure arm 50, see FIG. 10, is slidably guided in a frame portion 124 of its respective stanchion 48 and a hydraulic cylinder 126 and associated piston 128, the former of which is fixed to its stanchion '48 and the latter of which is fixed to its pressure arm, are effective to move the pressure arms in and out under the control of the operator and in conjunction with the in.

and out movement of

stanchions

34, 42.

Each pressure arm 50 carries an upstanding pressure member 130, similar in construction and function to the pressure members 110"and 1'12, previously described. That is to say, each member 130 includes an apertured hub 132 rotatably carried by an upstanding pin 134 fixed to the pressure arm 50 and has, on one side thereof, a

vertical pressure plate 136 which bears against the re spective chord 12.-

Two such pressure members 138 and 140 are used for the intermediate stanchions 42, see FIG. 8. 1n the case of the member 149, the pivot pin 142, therefor is removable so that this member may be repositioned, by replacing pin 142 in another opening in table '76, so as to accommodate for different pitches or for a hipped truss i121; as shown.

Insofar as the prestressing is concerned, this is accomplished by virtue of the relative displacement between the fixed and movable stanchions and by means of the pressure arms 50 in the case of the fixed end stanchions 48. When all chords and struts are placed and the nail plates are in position, the operator first actuates suitable controls to urge the movable stanchions toward each other andto simultaneously urge the pressure arms 50 inward. Such control mechanism may take the form of a control panel 162 such as is shown in FIG. 4, and preferably located on or near the center stanchion 32.

While the prestressing pressure is applied, the ram plates are forced upwardly to ram home both the upper and lower nail plates 16, the entire truss riding upwardly during this operation.

Although a certain specific embodiment of the invention has been shown and described, it is obvious that many modifications thereof are possible. The invention, therefore, is not to be restricted except insofar as is neces-. sitated by the prior art and by the spirit of the appended claims.

I claim:

1. A device for fabricating structural building. members joined by toothed metallic nail plates, comprising a base, a plurality of stanchion. units supported on said base and including at least one central unit with a pair of substantially as is shown in FIG. 3. -Whenall such nail plates, chords and strutsare placed, the machine is ready for the prestressing and nailplate ramming steps.

The aforementioned pressure plates 74, FIG. 3, which are fixed, flat plates or strips, are used in conjunction with I the lower chord members and find their equivalents, for I the purpose of the angled upper chords, in

elements

110 and 112, such a s are shown in FIG. 6. The

upper chords

12 or 12b shown in FIG. 6 hear against the

respective members

110 and 112 which, preferably, are pivotally mounted on table 76 so as to adjust automatically to any irregularities of these chord members and to also accommodate for different pitches of the upper chords. 7

Each of the movable stanchions 34Vand 42 are provided with wheels or rollers 11$, see particularly FIGS. 4 and 7,

intermediate units arranged on either side of the central unit and a pair of end units spaced beyond the respective intermediate units, each unit having a fixed first portion for engaging the lower chord structure'of a truss and a movable second portion for engaging the upper chord structure of such truss, said first portions of said units being aligned to support the lower chord structure of a trussin stationary straight position and said second portions individually being movable relative to the respective first portions in paths perpendicular to the alignment of said first portions to automatically accommodate selected angular positions between the elements forming the upper chord structure of a truss, the central and intermediate units being positioned to accommodate all of the points of intersection between chords and struts of the truss, said stanchion units being selectively movable relativeto each other in paths parallel, to the alignment of said first stanchion portions to accommodate difierent sizes and constructions of trusses, said stanchion units being provided with horizontally opening anvil structures to receive portions of the intersecting chords and struts and including an upper fixed anvil and a lower movable anvil in alignment with the fixed anvil, said lower anvil being adapted to support a lower nail plate thereon and the points of intersection between chords and struts being positioned between such anvils with an upper nail plate supported on the truss structure, means for simultaneous- 1y moving said lower anvils upwardly to ram both the upper and lower nail plates into the intersecting truss portions, and means for moving said second portion of each stanchion unit toward its respective first portion thereof immediately prior to movement of said lower anvils so as to prestress the chord structure prior to joining the component parts thereof.

2. The device according to claim 1 wherein said central and intermediate stanchion units each comprise a pair of stanchion members, one member of each pair constituting said first portion and the other member of each pair constituting said second portion, said means for effecting prestressing of the chord structure comprising hydraulic piston and cylinder assemblies for moving said other member of each pair toward its corresponding one member.

3. A stanchion unit for use in a device for prefabricating wood trusses comprising first and second stanchion members, the first stanchion member being fixed and the second stanchion member being movable toward and away from the first stanchion member, said stanchion members having horizontally aligned pockets for receiving intersecting chords and struts of the truss to be formed, means for selectively moving said second stanchion member toward the first member prestress to the chords and struts acted upon by such members, and means for joining the intersecting chords and struts within said pockets while the prestressing is applied thereto.

4. A device for prefabricating wooden trusses comprising a base member, a plurality of stanchion assemblies supported on said base member, said stanchion assemblies presenting a plurality of longitudinally aligned individual stanchions, each of which is provided with a horizontally opening pocket to receive a portion of the lower chord structure of a truss being formed, with such individual stanchions being spaced apart and aligned so as to support and position the lower chord structure when the same is bottomed within the several pockets, certain of the stanchion assemblies also including second individual stanchions spaced from but movable toward and away from their associated first mentioned individual stanchions, the second stanchions being provided with horizontally opening pockets aligned horizontally with and opposing the first mentioned pockets with which they correspond, the pockets of the second stanchions being so aligned as to receive the upper chord structure of the truss being formed and positioning the same when bottomed within the second pockets, means for moving said second stanchions toward the first stanchions to bottom the chord structures within their respective pockets,

membe rs toward the lowerchord membersto engage and 77 position the upper chord members relative to each other and to the lower chord members and to prestress the chords and struts interconnecting the chords, and joining the chords and struts at all points of engagement between the chords and the struts while the truss assembly is prestressed as aforesaid.

6. A device for fabricating structural building members joined by toothed metallic nail plates, comprising a base, a plurality of stanchion units's upported on said base and including at least one central unit with a pair of intermediate units arranged on either side of the central unit and a pair of end units spaced beyond the respective intermediate units, each unit having a fixed first portion for engaging the horizontal chord of a truss and a movable second portion for engaging the upper chord structure of such truss, said first portions of said units being aligned to support the lower chord structure of a truss in stationary straight position and said second portions individually being movable relative to the respective first portions in paths perpendicular to the alignment of said first portions to automatically accommodate selected angular positions between the elements forming the upper chord structure of a truss, the central and intermediate units being so' positioned as to accommodate for all of the points of intersection between chords and struts of the truss, said stanchion units being selectively movable relative to each other in paths parallel to the alignment of said first stanchion portions to accommodate dilferent sizes and constructions of trusses, means for joining the intersecting truss portions, and means for moving said second portion of each stanchion unit toward its respective first portion thereof immediately prior to operation of the joining means so as to prestress the chord structure prior to joining the component parts thereof.

7. A device according to claim 6 wherein said second portions of said stanchion units include pivotally mounted abutment means for accommodating automatically different angular positions of the upper chord truss members.

8. A device according to claim 7 wherein both said first and second portions of certain of said stanchion units comprise means for positioning struts between the chord members and restraining such struts from angular deviation during the prestressing thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,996,721 Black Aug. 22, 1961

Claims

5. THE METHOD OF PREFABRICATING WOODEN TRUSSES WHICH COMPRISES FIRST ARRANGING FRAMING MEMBERS SO AS TO FORM UPPER AND LOWER CHORDS AND STRUTS EXTENDING BETWEEN THE CHORDS, RIGIDLY POSITIONING THE LOWER CHORD MEMBERS, UNIFORMLY AND SIMULTANEOUSLY URGING THE UPPER CHORD MEMBERS TOWARD THE LOWER CHORD MEMBERS TO ENGAGE AND POSITION THE UPPER CHORD MEMBERS RELATIVE TO EACH OTHER AND TO THE LOWER CHORD MEMBERS AND TO PRESTRESS THE CHORDS AND STRUTS INTERCONNECTING THE CHORDS, AND JOINING THE CHORDS AND STRUTS AT ALL POINTS OF ENGAGEMENT BETWEEN THE CHORDS AND THE STRUTS WHILE THE TRUSS ASSEMBLY IS PRESTRESSED AS AFORESAID.