Single side truss stacker

A truss stacking system has a main conveyor for conveying trusses of a plurality of diverse designs out of a production facility and into a stack building yard or warehouse. The main conveyor is attended by a dedicated truss stacking station for each of the diverse designs, and which station includes a truss lift sub-station and a stack-forming sub-station. Each truss lift sub-station has at least a pair of traveling masts that each raises and lowers at least one bunk (eg., fork). The bunks are raised to lift a selected truss off the outflow conveyor, the masts are driven on an outbound journey to support the lifted bunk in the airspace above the stack-forming station, and then the bunks are lowered to rest the truss on the stack. Stop posts assist in stripping the truss off the bunks.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to article handling and, more particularly, to a truss stacker (or alternatively referred to also as, a truss stacking system).

It is an object of the invention to provide a single side truss stacker.

It is another object of the invention to provide a process line of plural single side truss stacking stations working to the side of (or straddling) a conveyor carrying an outflow of freshly made trusses from a truss making plant.

Single side truss stacking makes sense to conserve workspace in the work yard where the trusses are stacked. In a typical work yard, the land vehicles require much more real estate than the line of truss stacking stations. The land vehicles include the fork trucks that lift the stacks of trusses and the semi-tractors and flat bed trailers on which the fork trucks load the stack of truck from delivery away from the plant. Stacks of large trusses nowadays often require two, sometimes three, fork trucks working in concert. The amount of space required to make a 90° pivot, let alone a 180° pivot, is substantial.

So as a practical matter, it is impractical to stack on both sides of the process line because the real estate needs of the land vehicles is so great that the overall size of the work yard would be twice what a single side truss stacking line requires. In other words, the size of the work yard can literally be halved for a single side truss stacking line. The single side truss stacking line can be set up along a property line or the like where the work yard is landlocked, thereby maximizing the rest of the real estate that is available for the maneuvering of the large heavy land vehicles.

It is a further object of the invention to avoid hydraulics as well as scissor jacks. It is a corollary object of the invention that the power needs are met by electric power supply to electrodynamic appliances that power such drive trains utilizing any of gear, sprocket, spindle, chain, cable and so on:—but not hydraulics or scissor jacks.

It is a further object of the invention to configure the outflow conveyor as a series of generously spaced hurdles wherein the cross bar of which are rollers. Spacing which is generous is in the neighborhood of six feet (˜2 m) and greater. However, less generous spacing will serve the purpose. In the preferred embodiment, every other roller is driven, and the alternate rollers are idlers. In any event, not every roller need be driven. This spacing between the rollers provides the advantage of allowing workers to comfortably walk between spaced rollers. Among other reasons for facilitating pedestrian traffic between rollers includes the following. If for any reason any of the truss lift sub-stations stops working or else is taken offline (as for maintenance or the like), workers can still work manually in teams to lift off trusses transiting on the outflow conveyor and carry the trusses sideways to the stack forming sub-station. And the conveyor will pose no impediment to the manual lift and carry operation.

Preferably the driven rollers all have their own independent drives. They should turn at more or less the same speed, but exact precision is not needed.

A number of additional features and objects will be apparent in connection with the following discussion of the preferred embodiments and examples with reference to the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1, 2 and 17Ashow a truss stacking system50in accordance with the invention. The truss stacking system50comprises between one and a plurality of truss stacking stations100-I,100-II . . .100-N in accordance with the invention, preferably a plurality, arranged in a process line104determined by an outflow conveyor106. Each truss stacking station100-I,100-II . . .100-N comprises a truss lift sub-station110and a respective stack forming sub-station112.

The drawings show the outflow conveyor106to comprise a roller conveyor bed106permanently installed (ie., more or less permanently) in a work yard114adjacent to a truss-making plant116. Typically freshly made trusses120-I-A,120-II-A and so on (eg., trusses of a Type I style, and a Type II style and so on) transit out of the truss-making plant116on the roller conveyor bed106(eg, wherein riding on the roller conveyor bed106corresponds to State A for the trusses120, in contrast to State B which corresponds to the steps of being lifted and stacked in a stack122, and State C which corresponds to resting in a stack122, except State D corresponds to being the bottommost truss in a stack122).

The trusses120-I-A,120-II-A and so on are typically roof trusses or floor trusses. The work yard114is typically outdoors relative to the indoor truss-making plant116. But the work yard114can optionally be covered and still be outdoors, or fully enclosed and thus have its own indoor environment. However, being outdoors and uncovered is more typical.

FIGS. 1, 2 and 17Ashow that the truss-making plant116has an exterior wall formed with an opening124(eg., an open window124) that can be covered by a flap.FIG. 2shows that freshly made trusses120-I-A,120-II-A are conveyed from within inside the truss-making plant116to transit through the opening124therefore and to be continued to be conveyed on the roller conveyor bed106therefor.

Hence the roller conveyor bed106carries away the outflow of freshly built wooden trusses120-I-A,120-II-A from the truss-making plant106. Indeed, at any given moment, a plurality of such freshly made wooden trusses120-I-A,120-II-A are being propelled along over the tops of the roller conveyor bed106.

The roller conveyor bed106comprises a series of generously spaced hurdles126wherein the cross bars of which are rollers128,132. Spacing which is generous is in the neighborhood of six feet (˜2 m) and greater. However, less generous spacing will serve the purpose. In the preferred embodiment, every other roller128is driven, and the alternate rollers132are idlers. In any event, not every roller128,132need be driven. This spacing between the rollers128,132provides the advantage of allowing workers134to comfortably walk between spaced rollers128,132. Among other reasons for facilitating pedestrian traffic between rollers128,132includes the following. If for any reason any of the truss lift sub-stations110stop working or else are taken offline (as for maintenance or the like), workers134can still work manually in teams to lift off trusses120-I-A,120-II-A transiting on the outflow conveyor106and carry the trusses120-I-A,120-II-A sideways to the respective stack forming sub-station112. And the conveyor106will pose no impediment to the manual lift and carry operation.

Preferably the driven rollers128all have their own independent drives138. They should turn at more or less the same speed, but exact precision is not needed. The drawings show that each hurdle126of a driven roller128has an electric drive motor138mounted thereto.

Ultimately the roller conveyor bed106transports the freshly made trusses120-I-A,120-II-A past one or more truss stacking stations100-I,100-II . . .100-N in accordance with the invention.

FIG. 2shows trusses120-I-A,120-II-A being transported along the roller conveyor bed106and taken out of the factory's exit window124therefor.

FIGS. 3 and 4zoom in on the second downline truss stacking station100-II shown inFIGS. 1 and 2. It comprises a pair of masts140carried by respective carriages142that ride over respective rail and track systems144therefor. Each mast140elevates and lowers its own respective bunk146(eg., fork). The truss stacking station100-I,100-II . . .100-N might comprise three or four masts140, depending on the size of the trusses120-I-A,120-II-A to be stacked.

InFIGS. 1-5, the masts140and carriages142and bunks146are shown in a ‘home’ position150. Hence, for orientation of directions side to side, the masts140and carriages142as shown in these views are parked along the ‘home’ side148of the roller conveyor bed106. The opposite side of the roller conveyor bed106is the ‘stack forming’ side152. Hence the “home” position150is where the mast140and carriage142are parked along the home side148of the roller conveyor bed106, and bunk146is in a lowered position (at least below the conveyance plane156of the roller conveyor bed106). The “home” position150is detected by lasers, optics, limiter switches or the like (eg., see200inFIG. 17A).

FIG. 6shows that the masts140(only foreground mast140in view) have elevated the bunks146which in turn have lifted a given truss120-II-B above the plane156of the roller conveyor bed106. The timing of the lift is timed by detectors200better shown inFIG. 17A. The rollers128,132of the roller conveyor bed106keep rolling and do not stop. It is the elevating of the bunks146underneath the selected truss120-II-B that lifts the truss120-II-B off the roller conveyor bed106, and hence suspends further downline travel.

FIG. 7shows:—a mast140,a horizontally-traveling carriage142for carrying the mast140,portions of a bunk146,a vertically-traveling bracket158mounted on the mast140and cantilevering the bunk146,an electric-motor driven chain drive system162for elevating and lowering the bracket158and bunk146thereof,festooned electric conductors164for supplying the electric-motor driven chain drive system162for elevating and lowering the bracket158and bunk146thereof,a horizontal rail and track system144for the carriage142to travel to and fro across,an electric-motor driven chain drive system166for driving the carriage142on an outbound and inbound trips back and forth from the home side148to the far side of the stack forming side152,an I-beam168anchored on the ground and extending left and right under the plane156of the roller conveyor bed106from the home side148to the stack forming side152,the I-beam168having an upper pair of flanges172(only the downline flange172is in view),an inverted-V shaped, sharp-crested rail174mounted on top of the upper pair of flanges172of the I-beam168(see alsoFIG. 20),a pair of left and right V-grooved rail-riding wheels176(left and right given the orientation of the view) for riding on the inverted-V shaped, sharp-crested rail174(see alsoFIG. 20),a left-side only pair of front and back cam-rollers178for rolling against the undersurface of the upper flanges172of the I-beam168(left given the orientation of the view, and ‘front’ or downline roller in view since they are mounted on a common upline-downline axis180) (see alsoFIGS. 20, and17A),right-side only chin strap182stopping against the undersurface of the upper flange(s)172of the I-beam168in the unwanted circumstance that the mast140would be tipped counterclockwise in the view (wherein the mast140should never experience a counterclockwise tip over event, since all the applied vertical loads are always along a vector somewhere in the middle of the bunk146, and which thereby justifies why only a left-side pair of cam rollers178are utilized:—right-side cam rollers178would be non-involved) (again, orientations are relative the vantage point of the view) (see alsoFIG. 20), anda detector154that is mounted in a plane below the bunk146that senses the elevation of the top of the stack122such that the mast140does not drive the bunk146down into the top of the stack122when lowering the currently lifted truss120-II-b onto the top of the stack122, and wherein preferably this detector154comprises a laser device154and the beam axis156therefor is indicated in dashed lines.

Aspects mentioned above concerning the horizontal rail and track system144, the I-beam168, the upper flanges172thereof, the inverted-V shaped, sharp-crested rail174, a representative one of the pair of the V-grooved rail-riding wheels176, the pair of cam-rollers178, and the chin strap182are shown better inFIG. 20.

FIGS. 8-12and then14-16show basically that the mast140and bunk146have a travel circuit that is characterized by the following positions and/or movements:—a home position150(mast140retracted to the home side148of the roller conveyor bed106, bunk146at an elevation below the plane156of the roller conveyor bed106);a bunk146elevating movement186lifting a selected truss120-II-A off the roller conveyor bed106);an outbound transit movement188where the mast140travels from the home side148of the roller conveyor bed106to the stack-forming side152and where the bunk146(in cooperation with one or more other bunks146) suspends the selected truss120-II-b in the airspace above the stack122(or at least above ground stand-offs192on which the first truss120-II-D is directly deposited upon);a lowering movement194for the bunks146wherein the selected truss120-II-B is deposited on top of the stack122(or to be the first truss120-II-D of the stack122); and thena return to home position150movement196for both the mast140and bunk146, albeit the mast140and bunk are driven separately by their respective drive systems166and162.

To go all the way back toFIG. 2, it shows a worker134carrying a remote control unit136. He now has control for the length of time for this pause. When the mast140and bunk146have moved the selected truss120-II-B to the position ofFIG. 11, preferably there is a pause in the movements of both the mast(s)140and bunk(s)146. This gives the worker134the opportunity to walk around and under the truss120-II-B to see if the nail plates have been set adequately, and/or do other inspections. When satisfied, with his or her remote control unit136, he or she would enter a signal from the remote control unit136for the mast140and bunk146to complete the deposit of the truss120-II-B on the stack122. After that, and given the situation of things inFIG. 2, he or she can now inspect the recently-stacked truss120-II-D (or120-II-C) from above. Hence the worker134gives him or herself the opportunity to inspect each truss120from above and below.

So again,FIGS. 1-3show at least two truss stacking stations100-I,100-II in accordance with the invention, wherein each comprises a truss lift sub-station110and a stack forming sub-station112. The outflow conveyor106catches and carries a supply of freshly-made trusses120-I-A,120-II-A exiting a window124from a truss-making plant116.FIG. 4shows a selected truss120-II-A arriving at the respective truss stacking station100-II suited for it.FIG. 6shows the masts140lifting the bunks146(eg., forks) and hence the selected truss120-II-B to an elevated position (in all the side elevation views that follow, only the mast140and bunk146in the foreground are discernible).

FIG. 8shows things as they were inFIG. 5but is illustrated on a reduced-scale size to further show the stack-forming sub-station112.FIG. 9shows things as they were inFIG. 6but is illustrated on a reduced-scale size to further show the stack-forming sub-station112. In bothFIGS. 8 and 9, the trajectory of the truss120-II-B is shown in dashed-line arrows from being lifted off the roller conveyor bed106to being deposited at the stack forming sub-station112characterized by a plurality of ground stand-offs192. (eg., comprising for example and without limitation parallel rows of I-beams as shown better inFIG. 3 or 19). SoFIG. 9shows the selected truss120-II-B in solid lines and lifted above the plane156of the roller conveyor bed106, and held aloft in the airspace above the roller conveyor bed106, by the respective bunks146.

FIG. 10shows the masts140traveling across the rail and track system144therefor to transport the lifted truss120-II-B to an elevated position over the ground stand-offs192of the stack forming sub-station112.FIG. 11shows the masts140have completed the transit across the rail and track system144and support the lifted truss120-II-B in an elevated position in the airspace above the ground stand-offs192of the stack forming sub-station112.FIG. 12shows the masts140lowering their respective bunks146to deposit the truss120-II-B on top of the ground stand-offs192of the stack forming sub-station112(but if any earlier trusses120-I-D,120-II-C were stacked, then the bunks146would be depositing the lifted truss120-II-B on top of the stack122).

FIG. 13is a top plan view taken in the direction of arrows XIII-XIII inFIG. 12. It shows a representative one of the pair of bunks146in retreat under the lifted truss120-II-B as the masts140return to the home position150therefor. A stop post198is cooperating in stripping the lifted truss120-II-B off the bunk146.

FIG. 14returns to being a side elevation view comparable toFIGS. 8-12and shows the masts140returning back across the rail and track system144therefor to return to the home position150. Again, the stop posts198are cooperatively stripping the lifted truss120-II-B off the bunks146.FIG. 15shows further progress of the masts140returning back to the home position150therefor, and moreover showing further progress of the lifted truss120-II-B being stripped off the bunks146by the truss-stripping stop posts198, which are distributed in a pattern for this purpose.FIG. 16shows things in a position comparable toFIG. 8inasmuch as showing that the masts140have indeed returned back to the home position150therefor, which is the same position as inFIG. 8, and moreover showing that the first truss120-II-D of the stack122lies horizontally on the ground stand-offs192therefor (and which truss120-II-D will thereby represent the bottommost truss120-II-D of this stack122).

FIG. 17shows that the stack122now comprises several trusses120-I-D,120-II-C stacked horizontally on top of each other.FIG. 12shows better the detector154that is mounted in a plane below the bunks146that senses the elevation of the top of the stack122such that the masts140do not drive the bunks146down into the top of the stack122when lowering the current lifted truss120-II-B onto the top of the stack122. Preferably this detector154comprises a laser device154and the beam axis156therefor is indicated in dashed lines inFIG. 7.

FIG. 17Ais block diagram perspective view of the truss stacking system50in accordance with the invention showing that the work yard might comprise an indefinite number of sets of lift and stack forming sub-stations110and112. The sets110and112might not always be pairs. Each set of lift and stack forming sub-stations110and112might comprise three or more masts140and not just two as illustrated.

More significantly as shown inFIG. 17A, each truss stacking station100-I,100-II . . .100-N (whether it be two masts140or more) is associated with a detector200, preferably comprising an identifying and motion detecting function for both ‘identifying’ if the given truss120-I-A,120-II-A . . . is to be selected for lifting by the respective truss lift sub-station110and, if so, then also providing a signal for figuring the ‘timing’ when to lift the truss120-I-A,120-II-A . . . as it travels along the outflow conveyor106. The timing does not have to be perfect. The stop posts198are arranged to serve a second function beyond stripping alone. That is, the stop posts198are arranged to induce the trusses120-I-A,120-II-A . . . to stack in neat stacks122.

The invention having been disclosed in connection with the foregoing variations and examples, additional variations will now be apparent to persons skilled in the art. The invention is not intended to be limited to the variations specifically mentioned, and accordingly reference should be made to the appended claims rather than the foregoing discussion of preferred examples, to assess the scope of the invention in which exclusive rights are claimed.