Patent Publication Number: US-8984732-B2

Title: Method for assembling a structure

Description:
The present invention relates to a method according to the preamble to appended claim  1 . 
     BACKGROUND OF THE INVENTION 
     Within the industry for the manufacture of timber houses, e.g. prefabricated houses, and houses constructed from both wood and other materials, it is of major importance to be able to assemble structures, e.g. roof trusses, in as rapid and rational a manner as possible without jeopardising accuracy and reliability. It is further of importance that the positioning of the timber lengths which are included in the structure and which are cut and otherwise treated beforehand may be carried out rapidly and simply without any major risk of incorrect positioning. The laid-out timber lengths are fixed provisionally to one another by means of, for example, corrugated fasteners with the aid of a nail pistol or the like in order to make possible movement of the structure for the final fixing together of the timber lengths to one another at each joint by means of so-called corrugated fasteners which can be adapted to the different joints between the timber lengths. Thus, there is a major need in the art for an apparatus for rational handling of the corrugated fasteners and pressing of the correct corrugated fastener over the joint intended therefore. In recent years, it has proved that there is a further need for automation of the assembly procedure or interconnection (the nailing operation) of roof trusses. It is further desirable to be able rapidly and automatically to adapt equipment to suit different types of roof trusses. This implies that it is desirable to reduce and preferably eliminate the necessary downtimes or waiting times. 
     SUMMARY OF THE INVENTION 
     The task forming the basis of the present invention is to satisfy the above-outlined needs and wishes. 
     This task is solved according to the present invention in the method disclosed by way of introduction in that the method has been given the characterising features as set forth in appended claim  1 . 
     The present invention realises a method and an apparatus for rational and particularly rapid and efficient assembling (nailing) of such structures as roof trusses and the like. The method according to the present invention makes for an extremely high level of automation without jeopardising accuracy and other quality standards. Moreover, the method according to the present invention makes for the handling of structures of different types in one and the same apparatus or line, substantially without the need for any change over or switching time between structures of different, widely varying configurations and types in, in principle, any sequence whatever. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will now be described in greater detail hereinbelow, with reference to the accompanying Drawings. 
         FIGS. 1A-1B  are schematic perspective views of an apparatus or line for assembling structures in the form of roof trusses, for carrying the method according to the present invention into effect. 
         FIG. 2  is a block diagram of one embodiment of the method according to the present invention. 
         FIG. 3  is a view, on a larger scale, of the part of the apparatus illustrated in  FIG. 1B , as well as an inset view on an even larger scale of a part of a press unit included in the apparatus. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A method according to one embodiment of the present invention will now be described in greater detail hereinbelow, in connection with the assembly (nailing) of a number of different types of roof trusses and with reference to the apparatus or the line exemplified on the accompanying Drawings. 
     In  FIGS. 1A-1C  is exemplified the manufacture or assembly (nailing) of a number of different types of roof trusses. The apparatus in  FIGS. 1A-1C  may be combined with the parts in  FIG. 1A  in line with the parts in  FIG. 1B  and finally with the parts in  FIGS. 1A and 1B  in line with the parts in  FIG. 1C , this latter part having been cut off for technical drawing reasons. 
     The apparatus or the line in  FIGS. 1A-1C  comprises a number of roller conveyors  1 - 7  which, in the present embodiment, comprise servo-driven super- and/or subjacent rubber rollers. Beside the roller conveyors  1  and  2  are positioned two assembly tables  8  and  9  which may be so-called puck tables with automatically adjustable abutments or pucks. The adjustment of the abutments or pucks is carried out using computer processed drawing material as the point of departure. 
     The timber lengths are laid up in the proximity of the assembly tables  8  and  9  on pallets or the like and are marked in a suitable manner for the roof truss in question which is to be laid up on the assembly table  8  or the assembly table  9 . One roof truss is exemplified on the assembly table  8 , and another roof truss is exemplified on assembly table  9 . For rational handling, assembly may take place on the one table, while the timber lengths laid up on the other table are fixed to one another by means of, for example, corrugated fasteners or undulating plates in a per se known manner. 
     According to the present invention, the positioning and fixing of the corrugated fasteners take place with the aid of a nailing gantry  10  which includes a number of mutually displaceable nailing heads with corrugated fastener magazines and which are displaceable along, and thereby over, the assembly tables  8  and  9 . The displacement of the nailing heads and the gantry  10  takes place automatically, using computer processed drawing material as the point of departure. The gantry  10  and its nailing heads may be considered to be CAD guided to the joints and intersections which are to be provided with corrugated fasteners or undulating plates. 
     After the fixing of the timber lengths to one another on the assembly tables  8  and  9  to a provisionally assembled, and thereby as yet unfinished, or ready-nailed roof truss, e.g. the roof truss  11  on the roller conveyor  2 , the roof truss  12  on the roller conveyor  3  and the roof truss  13  on the roller conveyor  4 . The roof trusses  11 ,  12 ,  13  have been transferred from the assembly table  8  or  9  with the aid of lifting means for further transport on the roller conveyors  1 ,  2 ,  3  or  4 . The roof truss  11  on the roller conveyor  2  is composed of two upper frame lengths  14  and  15 , two diagonals  16  and  17 , a centre piece  18 , two side pieces  19  and  20 , as well as a bottom piece  21 , while the roof truss  12  on the roller conveyor  3  is composed of two upper pieces  22  and  23 , a side piece  24 , a number of diagonals  25  and  26 , a lower piece  27  and a further diagonal  28  ( FIG. 1B ). 
     Thus, the method according to the present invention permits different types of roof trusses  11 ,  12 ,  13  to follow after one another on the roller conveyors  1 ,  2 ,  3 ,  4  and further on the roller conveyors  5 ,  6 ,  7  without the need for any manual switching or adjustment of the roof truss line, which implies that everything takes place automatically, with the aid of computer processed drawing material or by CAD control. The only manual interventions take place at the assembly tables  8  and  9  where one or more operators place out the timber lengths with the aid of the automatically adjusted and set abutments or the pucks in the tables. 
     Between the roller conveyor  3  and the roller conveyor  4 , there is disposed a gantry  29  with a camera of the vision system type for observing or photographing the passing roof trusses and identifying them with the aid of a reference based on computer processed drawing material, e.g. a CAD file. With the aid of the camera system in the gantry  29 , information or data is also retrieved for nominal positional determination of that roof truss which is advanced further on the roller conveyor  4  up to a gantry  30  which includes a number of press units, of which one press unit  31  is shown on a larger scale in  FIG. 3 . The press units  31  are each provided with two cameras  32  and  33  which are also of the vision system type. The one camera  32  is mounted offset in the y-axis. The cameras  32  and  33  monitor the exact position for pressing of a corrugated fastener in position over the joint or intersection point in question on the roof truss. 
     The gantry  30  with the press units  31  may be of the type which is described in Swedish Patent Specification 0601495-5/530069, modified in a suitable manner with the cameras  32  and  33 , and with the aid of drivable control means for adjusting the press tool carriages included. 
     The roof truss finished with corrugated fasteners is advanced further via the roller conveyor  5  to the roller conveyors  6  or  7  for each type of roof truss, of which the one roller conveyor  6  is intended for one type of roof truss and the other roller conveyor  7  is intended for another type of roof truss, and which are equipped with driven discharge means and paths with stackers for separate roof truss packages. It is possible to have additional discharge roller conveyors for further roof truss types. 
     The camera gantry  29  need not be positioned between the roller conveyors  3  and  4 , but may, for example, be placed in over the roller conveyor  4 . A roof truss may be positioned both under the camera gantry  29  and partly in the press unit gantry  30 , where handling of roof trusses longer than the distance between the gantry  29  and  30  is permitted. 
     With reference to the block diagram illustrated in  FIG. 2 , parts of the method according to the present invention will now be illustrated in greater detail. The roller conveyor  3  on the one side of the gantry  29  supports a structure  34 , and the roller conveyor  4  on the other side of the gantry  29  supports a structure  35  which has been fed through the gantry  29  and observed by means of a camera  36  therein. The camera  36  is suitably a line scan camera which is rehearsed, in relation to computer processed drawing material, e.g. CAD data, to identify and positionally determine the structure  35 . Information from the camera  36  is fed to a computer or processor  37  which is connected to a pulse emitter  38  and to a system unit  39  of the master type. The system unit  39  feeds information about roof truss type to the processor  37  and to an additional computer or processor  40  which is also connected to the cameras  32  and  33  which are also connected to the system unit  39 . The processor  37  receives information from the system unit  39  about the incoming roof truss type and feeds back to the system unit  39  the position of the roof truss. The processor  40  also receives information from the system unit  39  concerning incoming roof truss type. The system unit  39  is further connected to the cameras  32  and  33  for setting thereof to nominal detail positions while information fed back to the processor  40  from the cameras  32  and  33  causes the processor  40  to transfer to the system unit  39  information on the assumed detail position and the next detail position. 
     The same reference numerals are employed in the different Drawing Figures. 
     Many modifications are naturally conceivable without departing from the scope of the inventive concept as defined in the appended Claims.