From the prior art are known apparatuses in which a suitable number of pieces of wood to be interlocked are pressed together end-on-end by pressing the outermost end faces between a fixed and a moving stopper.

The pieces are kept pressed for a certain period. After this, the thus formed, finally interlocked blank is removed and new pieces of wood are taken for interlocking.

A disadvantage of the known solution is its slowness due to the discontinuous method of operation.

To eliminate this disadvantage, the method relating to the invention is characterised in that the method includes the following stages - the pieces of wood (2) on the processing line to be interlocked are fed so as to form a continuous, preliminarily interlocked blank and made to move at a desired speed, - the preliminarily interlocked blank is cut with a cut-off saw (5), the said saw being arranged to move at the moment of cutting at the same speed as the blank to be cut, and

- the preliminarily interlocked pieces of wood (2) comprised in the cut blank are pressed together finally with a pressing device (6), the pressing device comprising at least one endless chain or belt (7), which is arranged to move parallel with the processing line, and which is divided by means of limiters (8,10) connected to it either directly or indirectly into two or more, at least approximately equally large parts so that of the limiters at the ends of each part at least one is a limiter (10) moving by power means (9) attached to the chain or belt (7), and that in turn, at each such part of the chain or belt (7), between the said limiters, is arranged to take place the final pressing together of the parts of the blank by the power means (9), at the same time as the blank moves continuously at the desired speed.

The apparatus relating to the invention is characterised in that the apparatus comprises - a feeding device for feeding the pieces of wood on the processing line to be interlocked so that they form a continuous, preliminarily interlocked blank, - feeding means for making the preliminarily interlocked blank move at a desired speed on the processing line of the apparatus, - a cut-off saw for cutting the preliminarily interlocked blank, the said saw being arranged to move at the moment of cutting at the same speed as the blank to be cut, and - a pressing device for pressing finally together the preliminarily interlocked pieces of wood comprised in the blank cut by means of the cut-off saw, the pressing device comprising at least one endless chain or belt, which is arranged to move parallel with the processing line, and which is divided by means of limiters connected to it either directly or indirectly into two or more, at least approximately equally large parts so that of the limiters at the

ends of each part at least one is a limiter moving by power means attached to the chain or belt, and that in turn, at each such part of the chain or belt, between the said limiters, is arranged to take place the final pressing together of the parts of the blank by the power means, at the same time as the blank moves continuously at the desired speed.

Since the part moving parallel with the pressing device chain or belt moves at the same speed as the pieces of wood being processed, the final interlocking of the parts of the blank taking place on the said moving part by means of compressing between the limiter which is fixed with respect to the chain or belt and the limiter which moves with respect to the chain or belt, will not cause any slowing down or interruption in the operation of the apparatus.

Further preferable developments of the invention are disclosed in the dependent claims.

The invention is described in greater detail in the following, with reference to the accompanying drawings, in which: Figure 1 shows the apparatus relating to the invention as a diagrammatic side view.

Figure 2 shows the apparatus relating to the invention as a diagrammatic top view.

Figure 3 shows a section along line III-III in Figure 1.

Figure 4 shows a section along line IV-IV in Figure 3.

Figures 1 and 2 show diagrammatically the apparatus for making finger joints continuously. By means of the apparatus, a number of pieces of wood 2 to be interlocked end-on-end by means of finger joints 1 are combined into a blank of desired length by exerting compressive force on the blank through the end faces of the blank during the hardening stage of the adhesive used in the joints 1 of the blank.

On the right-hand side in Figures 1 and 2, reference numeral 2 denotes the pieces of wood to be interlocked, provided with finger joint profiles at their ends. Reference numeral 3 denotes the feeding device by means of which the pieces of wood 2 on the processing line to be interlocked are fed so as to form a continuous, preliminarily interlocked blank. Reference numeral 4 denotes the feeding means which cause the preliminarily interlocked blank move at the desired speed on the processing line of the apparatus. The feeding rate effected by the feeding device 3 is higher than the feeding rate effected by the feeding means, due to which the individual pieces of wood 2 are pressed preliminarily against each other.

The cut-off saw 5 is arranged to cut the preliminarily interlocked blank at a precisely predetermined point. At the moment of cutting, the saw is arranged to move at the same speed as the blank to be cut. Most preferably, both the saw 5 and the blank to be cut move in the direction of feed of the processing line during sawing. It is, however, also possible to stop the movement of the blank for the duration of the sawing, whereby also the saw 5 will remain stationary with the exception of the working movement.

To ensure faultless sawing operation, on the processing line of the apparatus is provided at least one feeding means 4 on either side of the point of formation of the sawn groove 13 formed by the cut-off saw 5.

The preliminarily interlocked pieces of wood 2 comprised in the blank cut by the cut-off saw 5 are pressed together finally by means of the pressing device marked generally by reference numeral 6. In the example shown in Figures 1 and 2, the pressing device 6 comprises two endless chains or belts 7 which are arranged to move in the direction of the processing line.

On the chain or belt 7, or as in the example shown in Figures 1 and 2, between two chains or belts 7, are arranged fixed limiters 8 and moving limiters 10 provided with power means 9 alternately and at regular intervals.

In turn, one fixed limiter 8 and one moving limiter 10 provided with power means 9 are arranged to finally press together between them the parts of the blank moving on the processing line. Since both the fixed limiter 8 and the moving limiter 10 are supported only on the chain or belt 7, on it will be effected traction force corresponding to the pressing force exerted on the blank.

In the example shown in Figure 1, where there are two fixed limiters 8 and two moving limiters 10 provided with power means 9, during one cycle of the pressing device 6 takes place the final pressing together of the parts of four blanks.

By varying the length of the chain or belt 7 and/or the number of limiters 9, 10, a desired length can be selected for the blank to be pressed.

The endless chain or belt 7 comprised in the pressing device 6 is arranged to travel around two chain or belt pulleys 11 arranged at a distance from one another. The belt pulleys 11 are supported in a fixed manner on the shafts 15, which are in turn supported on bearings at one end 16 on the body of the apparatus. One of the shafts 15 is provided with power means (not shown) to rotate the shaft and thus the endless chain or belt 7.

The fixed limiter 8 on the pressing device 6 and the moving limiter 10 provided with power means 9 include a gripping part which is arranged to push into a slot 13 between two blanks formed by the cut-off saw 5, when the said slot arrives at the pressing device 6.

When the blank is at the pressing device 6, the power means 9 is arranged to exert a force on the blank which acts in a direction parallel to the direction of movement 12 of the blank or in a direction opposite to the said direction.

In Figure 1, in the blank which is at the pressing device 6 as a whole, the power means 9 presses in the direction of movement 12 and, correspondingly, when a blank arriving at the pressing device 6 from the right is at the pressing device 6 as a whole, the power means 9 presses in a direction opposite to the direction of movement 12.

In the direction of movement 12 of the blank, after the pressing device 6, is arranged another cut-off saw 14, which saw is arranged to move at the moment of cutting at the same speed as the blank being cut and to perform the cutting into a fixed size while the opposite end of the blank is supported on the fixed limiter 8 or the limiter 10 provided with power means 9. Cutting into fixed size can also be made precise when the limiter 10 is acting as a counterpart, when the power means 9 is guided to its extreme position for the duration of the moment of cutting. Finally, the feeding device 27 transfers the finished blank to the desired further processing stages or to intermediate storage.

Figure 3 shows a section along line III-III in Figure 1. To both chains or belts 7 is connected, in a manner known as such, a short piece of square hollow section inside which is fitted a power means 9 comprised in the example of Figure 3 of a hydraulic cylinder provided with a through-passing piston rod, the cylinder being fixed in an immobile manner to the square hollow section 17. Due to the through-passing piston rod, the surface area on the piston 18

is the same on both its sides and thus its force effect on both remains the same.

The piston rods 19 of both power means 9 are connected at one end to the limiter 10. On the right-hand side in Figure 3, the supply and return of the hydraulic oil of the power means 9 is arranged to take place via the limiter 10.

In the example shown in Figure 3, the power means 9 is shown in its other extreme position. By conducting pressure into the cylinder space 20, the power means 9 begins to move towards its other extreme position together with the other power means 9 functioning at the same time, which power means 9 will then move the limiter 10, which will in turn effect a compressive force on the end of the piece of wood 2. Similarly, exerting pressure in the cylinder space 21 will cause the limiter 10 to move in the opposite direction and thus the compressive force to be exerted on the end of the piece of wood 2 on the opposite side of the limiter 10.

Figure 4 shows a section along line IV-IV in Figure 3. In Figure 4 is described diagrammatically a guiding construction provided with adjustable walls 22-25 known from wood piece 2 planing machines, inside which the pieces of wood 2 travel and are finally pressed together between the fixed limiter 8 and the moving limiter 10 provided with power means 9.

As appears from Figures 1 and 2, a winding device 26 is provided for each parallel power means 9, for both the inlet and return hoses, which winding devices make possible the unwinding of the hydraulic hose and correspondingly bring about the rewinding of the hydraulic hose onto the reel while the power means 9 move on a path determined by the chains or belts 7.

The apparatus operates as follows.

In Figure 1 are marked sections A to E with arrows which depict the different stages of operation of the apparatus. In section A takes place the feeding of individual pieces of wood 2 onto the processing line of the apparatus.

In figure B, the feeding device presses the pieces of wood 2 together into a preliminarily interlocked blank, which is cut off by a saw 5 synchronically with the movement of the chain or belt 7 of the pressing device in such a way that the limiter 8 pushes into the sawn groove 13, which is spread if necessary, while the chain or belt 7 of the pressing device 6 rotates on its path around the chain or belt pulleys 11 and while the blank proceeds in the direction of movement 12. The limiter 9 will then push into the sawn groove to be made next and thus the operation continues uninterrupted.

In section C, the parts of the blank are pressed finally together between the fixed limiter 8 and the moving limiter 10 provided with power means 9.

Section C naturally moves continuously in direction 12.

Section D depicts a final, finished blank cut to fixed size with the saw 14.

Section E depicts a stage at which the finished blanks are moved to the desired further processing stages or to intermediate storage.