Method for assembling a structure

A method of assembling a structure of timber lengths, e.g. roof trusses, includes a number of upper and lower structure lengths or pieces, as well as a number of diagonals or braces etc., in which the timber lengths are laid out and fixed to one another. The structure formed from the timber lengths fixed to one another is observed by a first camera for positional determination of the structure and comparison of observation data with structure data and for controlling at least a second camera. The structure is fed into a unit for pressing in place of jointing pieces, e.g. corrugated fasteners, over the joints between the timber lengths by at least one positionable press unit, and the second camera observes the infed structure and positions the press unit at the correct position over a joint for pressing in place of a jointing piece.

The present invention relates to a method according to the preamble to appended claim1.

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 claim1.

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.

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.

InFIGS. 1A-1Cis exemplified the manufacture or assembly (nailing) of a number of different types of roof trusses. The apparatus inFIGS. 1A-1Cmay be combined with the parts inFIG. 1Ain line with the parts inFIG. 1Band finally with the parts inFIGS. 1A and 1Bin line with the parts inFIG. 1C, this latter part having been cut off for technical drawing reasons.

The apparatus or the line inFIGS. 1A-1Ccomprises a number of roller conveyors1-7which, in the present embodiment, comprise servo-driven super- and/or subjacent rubber rollers. Beside the roller conveyors1and2are positioned two assembly tables8and9which 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 tables8and9on 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 table8or the assembly table9. One roof truss is exemplified on the assembly table8, and another roof truss is exemplified on assembly table9. 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 gantry10which includes a number of mutually displaceable nailing heads with corrugated fastener magazines and which are displaceable along, and thereby over, the assembly tables8and9. The displacement of the nailing heads and the gantry10takes place automatically, using computer processed drawing material as the point of departure. The gantry10and 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 tables8and9to a provisionally assembled, and thereby as yet unfinished, or ready-nailed roof truss, e.g. the roof truss11on the roller conveyor2, the roof truss12on the roller conveyor3and the roof truss13on the roller conveyor4. The roof trusses11,12,13have been transferred from the assembly table8or9with the aid of lifting means for further transport on the roller conveyors1,2,3or4. The roof truss11on the roller conveyor2is composed of two upper frame lengths14and15, two diagonals16and17, a centre piece18, two side pieces19and20, as well as a bottom piece21, while the roof truss12on the roller conveyor3is composed of two upper pieces22and23, a side piece24, a number of diagonals25and26, a lower piece27and a further diagonal28(FIG. 1B).

Thus, the method according to the present invention permits different types of roof trusses11,12,13to follow after one another on the roller conveyors1,2,3,4and further on the roller conveyors5,6,7without 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 tables8and9where 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 conveyor3and the roller conveyor4, there is disposed a gantry29with 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 gantry29, information or data is also retrieved for nominal positional determination of that roof truss which is advanced further on the roller conveyor4up to a gantry30which includes a number of press units, of which one press unit31is shown on a larger scale inFIG. 3. The press units31are each provided with two cameras32and33which are also of the vision system type. The one camera32is mounted offset in the y-axis. The cameras32and33monitor the exact position for pressing of a corrugated fastener in position over the joint or intersection point in question on the roof truss.

The gantry30with the press units31may be of the type which is described in Swedish Patent Specification 0601495-5/530069, modified in a suitable manner with the cameras32and33, 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 conveyor5to the roller conveyors6or7for each type of roof truss, of which the one roller conveyor6is intended for one type of roof truss and the other roller conveyor7is 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 gantry29need not be positioned between the roller conveyors3and4, but may, for example, be placed in over the roller conveyor4. A roof truss may be positioned both under the camera gantry29and partly in the press unit gantry30, where handling of roof trusses longer than the distance between the gantry29and30is permitted.

With reference to the block diagram illustrated inFIG. 2, parts of the method according to the present invention will now be illustrated in greater detail. The roller conveyor3on the one side of the gantry29supports a structure34, and the roller conveyor4on the other side of the gantry29supports a structure35which has been fed through the gantry29and observed by means of a camera36therein. The camera36is 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 structure35. Information from the camera36is fed to a computer or processor37which is connected to a pulse emitter38and to a system unit39of the master type. The system unit39feeds information about roof truss type to the processor37and to an additional computer or processor40which is also connected to the cameras32and33which are also connected to the system unit39. The processor37receives information from the system unit39about the incoming roof truss type and feeds back to the system unit39the position of the roof truss. The processor40also receives information from the system unit39concerning incoming roof truss type. The system unit39is further connected to the cameras32and33for setting thereof to nominal detail positions while information fed back to the processor40from the cameras32and33causes the processor40to transfer to the system unit39information 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.