FIELD OF THE INVENTION The invention relates to an apparatus for cutting of wooden elements. The apparatus comprises a support surface for the wooden elements. The support surface is adapted for displacing the wooden elements from one side of the apparatus to another side of the apparatus. The apparatus furthermore comprises a circular saw blade, said saw blade having a cutting plane being oblique to the support surface, preferably being perpendicular to the support surface. The invention also relates to use of such apparatus and to the use of a mechanism for displacing the saw blade. Furthermore, the invention relates to e method for cutting wooden element by means of an apparatus according to the invention. BACKGROUND OF THE INVENTION

US 4,510,835 discloses an apparatus for cutting wooden elements. The apparatus includes a base carrying an elongated slide plate having a longitudinal slot adjacent one end . An indexing assembly is disposed between the base and the elongated slide plate and engages within the slot of the slide plate to constrain one of its ends to longitudinal movement, and a crank rotatably connects the base to the medial portion of the slide plate. A first motor is mounted on the other end of the slide plate to rotatably support the blade, and a second motor may be carried by the base for rotating the crank to move the slide plate from side to side and up and down along the slot and thereby move the saw blade along an elliptical path. In operation, the second motor turns the crank to cause the blade to be brought into contact with the workpiece along a path generally parallel with a major axis of the elliptical path. The movement of the machinery elements is a combination of longitudinal movement and rotary movement which result in high accelerations and decelerations. Longitudinal movement in a slot reduces speed of operation and can reduce durability and functional reliability of the machinery elements. SUMMARY OF THE INVENTION

It may be seen as an object of the invention to provide an apparatus and a working method of such which is capable of cutting wooden elements in an efficient and sufficient manner without impeding the cutting speed, but on the other hand improving cutting speed. It may also be seen as an object of the invention to improve the durability of fast-moving machinery elements. It may further be seen as an object to reduce the cost of manufacture and/or of maintenance and/or of operation of an apparatus for cutting wooden elements.

One or more of the objects of the invention may be accomplished by an apparatus with a said saw blade being displaceable from the first position to the second position and vice versa by a displacement mechanism, said mechanism

comprising

- an axle of the saw blade, said axle of the saw blade mounted rotatably relative to a rotor of the apparatus, an axle of the rotor, said axle of the rotor mounted rotatably relative to a chassis of the apparatus, where

- said axle of the saw blade is arranged substantially parallel to said axle of the rotor, and where said axle of the saw blade is mounted for performing a planetary movement around the axle of the rotor,

wherein a distance between the axle of the saw blade and the axle of the rotor is smaller than a radius of the saw blade.

An apparatus for cutting wooden element must be operating fast. By operating the saw blade purely by rotational movement, and not incorporating any translational movement result in the operation of the saw blade being faster. The speed of some cutting processes, when cutting wooden elements, has been reduced by at least 25%, e.g. from a time for cutting of 0.120 second to 0.080 second. The speed of cutting and thus the time spend when cutting is dependent on the height and the width of the wooden element being cut.

Therefore, when using an apparatus according to the invention, and when using a mechanism as stated in an apparatus for cutting wooden elements, the speed of cutting and thus the time spend for cutting may be reduced more or less compared to known cutting of wooden elements. An advantage of a distance between the axle of the saw blade and the axle of the rotor being smaller than a radius of the saw blade may be that the planetary motion of the axle of the saw blade around the axle of the rotor has a radius smaller than the radius of the saw blade and hence forces necessary for providing the planetary motion is smaller than if the distance was greater than the radius of the saw blade. Smaller forces may diminish the requirements on materials, dimensions and power of motors of the apparatus. Furthermore, the time needed for making a planetary ovement of the saw blade from the first position to the second position may be diminished resulting in shorter time intervals needed for cutting a wooden element, said shorter time intervals leading to an increased cutting capacity of the apparatus.

However, by operating an apparatus for cutting wooden element fast, there is a risk that the wooden chips resulting for the cutting will clog up between the teeth of the saw blade, thus reducing or even inhibiting further cutting.

Another advantage obtained by the apparatus according to the invention is that when cutting wooden elements, clogging of the teeth of the saw blade is limited or even eliminated. This is due to the fact that each teeth of the saw blade is engaging the wooden element within a shorter period of time than apparatuses according to prior art. The effect is especially profound when the rotation of the saw blade is the same, i.e. clockwise or counter-clockwise, as the rotor.

In an embodiment of the apparatus, a support surface for the wooden elements is provided, said support surface being adapted for displacing the wooden elements from one side of the apparatus to another side of the apparatus, and the center of the planetary motion of the axle of the saw blade is below the support surface with respect to gravitation. An advantage of this may be that the rotor, including the axle of the saw blade, and supporting the saw blade has a stable position in relation to gravity being below the support surface. Sawing with the saw blade by providing the saw blade a planetary displacemenet around the axle of the rotor is accomplished by surmounting gravity. Thus, for maintaining the saw blade in the stable postion, no forces applied by the apparatus are needed for maintaining the saw blade in the stable position, gravity maintains the sawblade in the stable position. In an aspect of operating the apparatus according to the inventon, a torque is transmitted from a drive shaft of a motor to the axle of the saw blade, with respect to an axis of rotation of the axle of the saw blade, and wherein the axle of the saw blade and the drive shaft are displaced with respect to each other. This embodiment may be advantageous because it enables a drive shaft of a motor to be placed non-coaxially with the axle of the saw blade, resulting in the drive shaft of the motor not needing to follow the planetary motion of the axle of the saw. Another advantage may be that the drive shaft of the motor for generating the torque rotating the the saw can be coupled directly to the drive shaft in a fixed manner, i.e., without the torque having to be transferred along torque

transferring joints being flexible with respect to the axis of the torque, and the motor will follow the planetary motion of the axle of the saw. In a particular embodiment, the drive shaft is placed in the center of the planetary motion of the axle of the saw.

In an embodiment of the apparatus, a drive shaft of a motor is connected to the axle of the saw blade, and wherein

- the axle of the saw blade and the drive shaft are parallel,

- displaced radially with respect to each other, and

wherein the drive shaft and the axle of the saw blade are coupled directly so as to enable transmission of a torque from the drive shaft to the axle of the saw blade by rotating the axle of the saw blade around an axis of rotation being orthogonal to the plane of the saw blade. By 'coupled directly' is understood, that the exchange ratio between the axle of the saw blade and the drive shaft is fixed at unity.

In a particular embodiment according to the invention, the axle of the saw blade and the drive shaft of the motor are parallel and displaced radially and are arranged so that forces applied by the drive shaft on the axle of the saw blade have components being parallel to the axis of the axle of the saw blade. Examples of this includes a cardan shaft and a magnetic clutch. An advantage of this may be transfer of torque from the drive shaft of the motor to the axle of the saw blade being performed without transferring torque to the rotor. In particular embodiments, forces for applying a torque on the axle of the saw blade are acting between an end of the axle of the saw blade and an end of drive shaft. In an embodiment of the apparatus, a torque is transmitted from a drive shaft to the axle of the saw blade, so as to rotate the axle (6) of the saw blade around an axis of rotation being orthogonal to the plane of the saw blade, with the torque being generated with respect to an axis of rotation of the axle of the saw blade, wherein at least one force component for generating the torque is applied to the axle of the saw blade in at least one point of application on the axle of the saw blade, which at least one point of application of the at least one force component is located on the axis of the axle of the saw blade so that the sum of the at least one of force component applies substantially no torque on the rotor, such as no torque on the rotor. This may be advantageous in that the torque applied to the rotor is diminished, such as substantially eliminated, such as eliminated. An advantage of this may be that the axle of the saw blade can be rotated without applying a torque on the rotor. In a particular embodiment, the net force generated on the rotor in a direction being orthogonal to the axle of the saw blade and being orthogonal to a vector from the center of the rotor to the axis of the axle of the saw blade, leads to a torque on the rotor which is less than a torque needed to move the saw blade from a first position to a second position. The torque needed to move the saw blade form a first position to a second position may in some embodiments be substantially equal to a torque applied on the rotor by gravitational forces acting on the rotor.

In another embodiment, a torque is transmitted from a drive shaft to the axle of the saw blade, so as to rotate the axle of the saw blade around an axis of rotation being orthogonal to the plane of the saw blade, wherein a plurality of force components for generating the torque is applied to the axle of the saw blade in a plurality of points of application on the axle of the saw blade, which points of application of force components are distributed around the axis of the axle of the saw blade so that the plurality of force components substantially cancel each other in terms of net force component in a direction being orthogonal to the axle of the saw blade and being orthogonal to a vector from the center of the rotor to the axis of the axle of the saw blade.

In one embodiment of the apparatus, the apparatus comprises a cardan shaft , said cardan shaft extending from an input end of the shaft to an output end of the shaft, said input end mounted in a bearing of a chassis of the apparatus and said output end mounted to the axle of the saw blade.

In an alternative ambodiment of the apparatus, the apparatus comprises a magnetic clutch, said magnetic cluch having a drive disc mounted in a bearing of a chassis of the apparatus, and said magnetic clutch having a driven disc to be driven by the drive disc and mounted to the axle of the saw blade.

In another particular embodiment, the magnetic clutch or cardan axle is arranged so as to enable force transfer between two parallel axles which are radially displaced with respect to each other. An advantage of using a magnetic clutch may be that there need not be mechanical transfer of torque between the axles, hence wear, noise and friction is limited compared to mechanical transfer of torque.

Advantages of using a cardan shaft may include that the principle of operation eliminates any slip between the two axles. Transfer of torque from one axle to the other by means of a cardan shaft is performedmechanicallywith an exchange ratio between the axles fixed at 1 : 1 (one-to-one) at all times, thus, there is no slip between the axles (where one axle rotates with respect to the other), the angular displacement of the axles are at any time fixed with respect to each other.

For both cardan shaft and magnetic clutch applied for transferring torque, it may be an advantage, that torque may be applied to the axle of the saw blade in a manner where there is substantially no torque applied on the rotor.

In an embodiment of the apparatus, the apparatus further comprises a brake mechanism, such as an air brake, such as a pneumatic brake, arranged for braking the rotation of the rotor, i.e., braking the planetary motion of the axle of the saw blade and thereby braking the planetary rotation of the saw blade around the axis of rotation of the rotor upon activation of the brake mechanism. An advantage of such brake mechanism may be that the rotation of the rotor may be limited, and possibly stopped, such as stopped fast, possibly within few seconds. Fast stopping of the rotation of the rotor may be beneficial for safety reasons, since the corresponding planetary rotation of the saw blade may be dangerous. In a particular embodiment, the brake mechanism is activated by a contact detecting personnel handling of the apparatus possibly dangerous to personnel operating the apparatus, such as a contact detecting opening of a door of the apparatus. One example where the brake mechanism, such as the air brake, may be activated is upon an emergency stop where the first drive motor (which is provided for driving the saw blade) stops and brakes the rotation of the saw blade 5 and axle 6 of the saw blade around the axis of the axle of the saw blade. Due to conservation of angular momentum, the rotor may start to rotate, however, this may be avoided by activating the brake mechanism.

An apparatus according to any of the preceding claims, where the apparatus further comprising a slip clutch, such as a magnetic powder clutch, arranged for transferring torque from an input shaft of a drive motor to the axle of the saw blade, and facilitating slip between the input shaft of the drive motor and the axle of the saw blade. In an embodiment of the apparatus, the apparatus further comprises a slip clutch, such as a torque limiter, such as a magnetic powder clutch, arranged for transferring torque from an input shaft of a drive motor to the axle of the saw blade, and facilitating slip between the input shaft of the drive motor and the axle of the saw blade. The slip clutch may be positioned between the axle of the saw blade and the drive axle of the motor intended for for driving the saw blade. In certain embodiments of the invention, a torque applied on the rotor may lead to a rotation of the rotor which generates a torque on the axle of the saw blade to rotate, which in turn makes the axle of the saw blade rotate. Rotation of the saw blade generated by a torque applied on the rotor may apply a torque on the motor intended for driving the axle of the saw blade, said rotation of the saw blade may result in the motor acting as a generator, which is not wanted. Having a a slip clutch positioned between the axle of the saw blade and drive shaft of the motor for driving the saw blade allows the axle of the saw blade to rotate without a corresponding rotation of the drive shaft of the motor. In a preferred embodiment of the apparatus according to the invention, the rotor constitutes a circular element, and where the circular element has a centre along a longitudinal axis of the axle of the rotor and where the rotor has an outer circumference surrounding the axle of the saw blade so that a section of the axle of the saw blade extending within the rotor lies within the outer circumference of the rotor. The rotor having an outer circumference surrounding the axle of the saw blade has the advantage that axles and especially bearing are protected form saw dust from the cutting of the wooden elements. Also, the planetary movement is accomplished in a manner reducing the number of machinery elements to the minimum, thus increasing durability and reliability of the apparatus.

Preferably, the axle of the saw blade is driven by a motor along a belt drive, and also the axle of the rotor is driven by a motor along a belt drive. Belt drives are drive mechanisms being easy to adjust to a correct tensioning of the belts.

Furthermore, belt drives are drive mechanisms with a reduced noise level compared to other drives such as chain drives and gear drives.

In an embodiment of the apparatus according to the invention, the axle of the saw blade is provided with a gear wheel, and the axle of the rotor is also provided with a gear wheel, said gear wheel of the rotor intermeshing with the gear wheel of the saw blade so that said saw blade is capable of a planetary or orbital movement around the gear wheel of the rotor.

A gear wheel drive is a drive mechanism being capable of transferring large forces and torques which may be necessary in the apparatus according to the invention, where the saw blade is rotating at high speed and where cutting of the wooden elements, especially wooden element made from hard wood such as oak and such as many of the wooden species form the tropics, i.e. form Southeast of Asia, from Africa and from South America. Also, the speed of operation as mentioned above results in the cutting taking place very fast, not leaving time for the saw blade to 'gently' cutting through the wooden element - cutting is more Yough'.

Preferably, the axle of rotor is driven by a motor being adapted for individual control, so that the planetary movement of the saw blade may be provided individually and separately from operation of other elements of the apparatus, at selected period of time depending on the cutting of the wooden elements.

Separate driving of the drive motor for the rotor results in driving taking place at any desired time interval during cutting, at any desired speed and at any desired acceleration and deceleration of the saw blade when the saw blade starts from the first position, enters into the second position and returns to the first position.

In a possible embodiment of the apparatus according to the invention, a distance in a plane parallel with the plane of the saw blade between the rotational axis of the axle of the saw blade and the axle of the rotor, respectively is at least 30 mm, preferably between 30 mm and 120 mm, possibly between 40 mm and 100 mm, even possibly between 40 mm and 80 mm, or in the alternative possibly between 60 mm and 120 mm, even possibly between 80 mm and 120 mm.

In the possible embodiment of the apparatus according to the invention, the apparatus is adapted for cutting wooden elements having a cross-sectional area with a width between 20 mm and 500 mm and a height between 5 mm and 125 mm.

Apart from applying different distances in a plane parallel with the plane of the saw blade between the rotational axis of the axle of the saw blade and the axle of the rotor, it will additionally be possible to use saw blade with different diameters. Especially if the distance is relatively high, it will be possible to use saw blades having a relatively larger diameter compared to saw blades capable of being used, if the distance is relatively low. A combination of a relatively large distance such as 120 mm and a relatively large diameter saw blade such as 700 mm makes it possible to cut wooden elements with a large width or a large height. In a preferred embodiment of an apparatus according to the invention, the support surface is provided with an aperture, said aperture being adopted for allowing the saw blade to move from the first position to the second position, said second position being a position for cutting the wooden elements on the support surface.

Preferably, the entire saw blade is positioned below the support surface when being in the first position, and a major part of the saw blade also being positioned below the support surface when being in the second position. Accordingly, the support surface is provided with an aperture for at least part of the saw blade passing though the support surface during cutting of the wooden element, because cutting takes place from the support surface and upwards through the support surface.

In an alternative embodiment, the entire saw blade is positioned above the support surface when being in the first position, and the entire saw blade also being positioned above the support surface when being in the second position. Accordingly, the support surface need not an aperture, because cutting of the wooden element takes place from above and downwards towards the support surface.

According to a second aspect of the invention, there is provided a method of operating an apparatus for cutting wooden elements, said method comprising the steps of rotating the saw blade around an axle of the saw blade by operating a motor driving the axle of the saw blade, rotating the saw blade around an axle of a rotor by operating a motor driving the axle of the rotor, thereby providing a centre of the saw blade a planetary movement around the axle of the rotor resulting in displacing the saw blade from a first position to a second position along the planetary movement, cutting a wooden element when the saw blade is in the second position, during the planetary movement, and displacing the saw blade further from the second position to the first position along the planetary movement, wherein a distance between a centre axis of the axle (6) of the saw blade and a centre axis of the axle (13) of the rotor is smaller than a radius of the saw blade. In a particular embodiment, the method further comprises transmission of a torque from a drive shaft to the axle of the saw blade, wherein a torque applied by gravity on the rotor has a magnitude being at least as large as a torque applied on the rotor by said transmission. An advantage of this may be, that if the torque applied on the rotor is given only by the sum of the torque applied by gravity and the torque applied by said transmission, then the rotor will turn into a

substantially fixed angular position, such as the first position. BRIEF DESCRIPTION OF THE INVENTION

The invention will hereafter be described with reference to the drawings, where Fig. 1 is a sketch showing cutting of a wooden element by saw blade such as a saw blade of an apparatus according to the invention,

Fig. 2 is a photograph showing a possible embodiment according to the invention of the apparatus for cutting wooden element,

Fig. 3 is a photograph showing a first close-up of a support surface and drive rollers of the apparatus shown in Fig. 2,

Fig. 4 is a photograph showing a second close-up of a support surface and drive rollers of the apparatus shown in Fig. 2,

Fig. 5 is a drawing showing an embodiment of the apparatus according to the invention, seen in a plane parallel to the saw blade,

Fig. 6 is a drawing showing an embodiment of the apparatus according to the invention, seen in a plane perpendicular to the saw blade,

Fig. 7 is a drawing showing an embodiment of the apparatus according to the invention, seen in plane parallel to the saw blade where the a axle of the saw is driven via a cardan shaft,

Fig. 8 is a drawing showing an embodiment of the apparatus according to the invention, seen in plane parallel to the saw blade where the a axle of the saw is driven via a magnetic clutch,

Fig. 9 shows schematic plane view figures illustrating some of the forces applied for different embodiments,

Fig. 10 shows a schematic plane view figure illustrating some of the forces applied for an embodiment, and

Fig. 11 is a drawing showing another embodiment of the apparatus according to the invention, seen in a plane perpendicular to the saw blade. DETAILED DESCRIPTION OF THE INVENTION

Fig. 1 is a perspective view of a cutting method for cutting wooden elements on an apparatus according to the invention. The wooden element 1 is a longitudinal stave intended for being cut into a plurality of shorter staves 2. The cutting is performed by the wooden element 1 being passed through means for displacing the wooden element such as lower drive rollers 3 as shown in the figure. Other means for displacing the wooden element may be used, such as drive belts, drive sprocket, or other machine elements suited for displacing the longitudinal wooden element. Upper rollers 4 are intended for holding the wooden element in contact with lower drive rollers 3. The upper rollers 4 may or may not be drive rollers. Alternatively, the upper rollers 4 may be the drive rollers and the lower rollers 3 may or may not be driven. In still an alternative embodiment, the lower rollers 3 and the upper rollers 4 are both set of non-driven rollers, and displacement of the wooden element is performed by any another means suited therefore.

During displacement of the wooden element 1, the element is stopped shortly by means of the lower drive rollers 3 and the upper rollers being stopped. During the stop, a circular rotating saw blade 5 is passed through the wooden element 1, thus cutting the wooden element along a cut being perpendicular to the

longitudinal direction and perpendicular to the displacement direction, as shown by the arrow, of the wooden element. Cuts other than perpendicular may in some cases be provided, however, wooden elements being cut are often used as parquet blocks, floor boards or other wooden element to be used with an end surface being perpendicular to the longitudinal extension of the wooden element.

Fig. 2 shows an apparatus comprising a support surface comprising bottom drive rollers 3 (see also Fig . 3 and Fig. 4) and also comprising upper rollers 4 for holding the wooden element 1 in contact with the lower drive rollers 3. Fig. 3 is a close up view showing the wooden element 1, the support surface constituted by the lower drive rollers 3 and also showing the upper rollers 4. The lower drive rollers 3 are intended for displacing the wooden element 1 in a direction tangentially to the rollers 3,4, in the figures in a direction from right to left. The speed of displacement may be as high as 500 m/min corresponding to approximately 8.5 m/sec. The drive rollers 3 are driven in a manner where the wooden element 1 is alternately driven and stopped. The wooden element 1 is stopped each time the wooden element 1 is to be cut by the saw blade 5 (see Fig. 4). Fig. 4 shows cutting of the wooden element 1 at selected intervals along the longitudinal extension of the wooden element 1. Cutting is performed by the saw blade 5 being moved from a first retracted position underneath the support surface (se Fig. 5) to a second projecting position, as shown in Fig. 4, where at least part of the saw blade 5 extends above the support surface. Fig . 4 shows the saw blade 5 being projected to a position where the wooden element 1 is completely cut through. The saw blade 5 is moved from the first retracted position to the second projected position within a very short time interval. The time interval must be small in order not to slow down to much the cutting of the wooden element 1 into more blocks, staves or other smaller elements. Fast cutting of the wooden element 1 is an essential parameter in order to obtain a sufficiently and satisfactory high cutting capacity of the apparatus.

Fig. 5 is a plane view of a drive mechanism of an apparatus according to the invention. Apart from a mechanism for driving the saw blade, the support surface consisting of drive rollers 3 are shown, the upper rollers 4 are shown and the wooden element 1 is shown schematically. Also the saw blade 5 is shown in the first retracted position. The mechanism comprises an axle 6 for the saw blade 5. The saw blade 5 is secured to the axle by means of clamping elements 7. The saw blade axle 6 is supported in inner rings of a first set of angular contact ball bearings 8,9. Other types of bearings may be utilised instead. The outer rings of the first set of angular contact ball bearings 8,9 are supported in a rotor 10. The saw blade axle 6 is further provided with a gear wheel 11 mounted on the saw blade axle 6 between the angular contact ball bearings 8,9. The gear wheel 11 is intermeshing with a corresponding gear wheel 12, also shown schematically in Fig. 6.

As mentioned, the mechanism furthermore comprises a rotor 10. The rotor 10 comprises an axle 13 supported in inner rings of a set of circular ball bearings 14,15. Other types of bearings may be utilised instead . The outer rings of the set of circular ball bearings 14,15 are supported on a chassis 16 of the apparatus. The rotor axle 13 is secured to the rotor as such by one or more bolts 16. Other means for securing the rotor axle 13 to the rotor 10 may be used such as groove and tongue. A drive shaft 17 for the saw blade 5 extends through the rotor axle 13. The drive shaft 17 for the saw blade 5 is supported in inner rings of a second set of angular contact roller bearings 18,19. Outer rings of the second set of angular contact roller bearings 18,19 are supported by the rotor axle 13. The rotor axle 13 is 5 hollow, allowing the drive shaft 16 for the saw blade 5 to extend there-through.

The drive shaft 17 for the saw blade 5 is provided with the gear wheel 11 mounted on the drive shaft 17 on the left of the one angular contact roller bearing 18. Other types of bearings may be utilised instead. The gear wheel 12 is

10 intermeshing with the gear wheel 11 of the saw blade axle 6, also shown

schematically in Fig. 6. A first drive motor 20 is provided for driving the drive shaft 17 for the saw blade 5 and thus driving the saw blade 5 along the gear wheels 11,12. The first drive motor 20 is driving the drive shaft 17 of the saw blade 5 along one or more belts 21. Other means of transfer than belts may be

15 provided, either gear wheels, chain drive or the drive shaft of the saw blade being the drive shaft of the motor, i.e. a direct drive of the drive shaft.

A second drive motor 22 is provided for driving the rotor 10 and thus driving the saw blade 5 along a planetary or orbital path (see Fig. 6). The second drive motor 20 22 is driving the rotor 10 along one or more belts 23. Other means of transfer than belts may be provided, either gear wheels, chain drive or the drive shaft of the saw blade being the drive shaft of the motor, i.e. a direct drive of the drive shaft.

25 During operation of the apparatus, the first drive motor 20 and the second drive motor 22 are each operated individually and separately from each other.

The first drive motor 20 is preferably driven continuously in order for the saw blade 5 to be ready for cutting the wooden elements 1 at any time during passing 30 of wooden element 1 along the support surface, see Fig. 1 and Fig . 4. Thus, the saw blade 5 is rotating continuously around the saw blade axle 6, driven by the first drive motor 20 along the belts 21, along the drive shaft 17 for the saw blade 5, and along the gear wheels 11,12. Rotation of the saw blade 5 is independent from any rotation of the rotor 10. Thus, the saw blade 5 is preferably rotating both when being in the first retracted position as shown in Fig . 5 and when being in the second projected position (see Fig . 1 and Fig . 4) .

The second drive motor 22 is only driven when the saw blade 5 is to be displaced from the first retracted position to the second projected position, and vice versa . The second drive motor 22 is preferably a stepper motor or a servo motor. The second drive motor 22, when operated, will provide the rotor 10 with one full rotation, i.e. 360 degrees rotation, around the rotor axle 13, driven by the second drive motor 22 along the belt 23. Rotation of the rotor 10 around the rotor axle 13 is performed independently from rotation of saw blade 5 around the saw blade axle 6. Thus, the rotor 10 is rotating only when the saw blade 5 is to be displaced from the first retracted position to the second projected position .

Rotation of the rotor 10 around the rotor axle 13 is preferably a continuous rotation . Thus, the rotation speed is not limited neither when the saw blade starts cutting the wooden element, nor during the further cutting of the wooden element. A continuous rotation of the rotor and thus a planetary or orbital movement of the saw blade around the rotor axle results in a cutting of the wooden element having both a component along the height of the wooden element and a component along the width of the wooden element.

Also, a continuous rotation of the rotor will result in the planetary or orbital movement of the saw blade possibly having a maximum speed during cutting of the wooden element, with no change of acceleration direction during cutting of the wooden element, i.e. no change of acceleration from upwards to downwards during cutting of the wooden element.

Fig . 6 is a plane view of the planetary or orbital movement of the saw blade 5 around the rotor axle 13. The saw blade axle 6 is shown rotating counter- clockwise, driven along the gear wheels 11, 12 by the drive shaft 17 for the saw blade rotating clock-wise. In the figure, the saw blade 5 is shown by full lines in the first retracted position .

When the saw blade 5 is to be moved from the first retracted position to the second projected position and back to the first retracted position, the rotor 10 is driven by the second drive motor 22. In the embodiment shown, the rotor 10 is rotated counter-clockwise, thereby bringing the saw blade into the second projected position faster than if the rotor were rotated clock-wise. However, this is because the saw blade axle in the first retracted position is in a position right to the rotor axle. If the saw blade axle would have been in a position left to the rotor axle, the rotor would have to be rotated clockwise to bring the saw blade into the second projected position as fast as possible.

The apparatus gives the opportunity to select the rotational direction of the saw blade independently on the rotational direction of the rotor, and thereby adjusting, optimising or controlling the saw blade operation .

If the rotational direction of the saw blade is the same as the rotational direction of the rotor, the saw blade is said to be cutting "with" the rotor. Same rotational direction of the saw blade and of the rotor may result in chips, which are formed during cutting, being expelled from the cutting area more efficiently than if the rotational direction of the saw blade and the rotor were opposite each other.

Furthermore, same rotational direction of the saw blade and of the rotor, i.e. when the saw blade is said to be cutting "with" the rotor, result in the torque needed of the rotor motor for rotating the rotor being limited compared to when the rotational direction of the saw blade and of the rotor are the opposite.

Selecting the rotational direction of the saw blade, either the same as or the opposite as the rotational direction of the rotor, gives the opportunity to select a cutting process which is optimised in relation to obtaining a certain surface quality of the end surface of the wooden element being cut. The surface quality may be the roughness or the extend of possible burrs along one or more edges of the end surface, thus possibly limiting or eliminating burrs along one or more edges which will be visible during end use of the wooden element, e.g . as a parquet flooring .

The dotted line 24 shows the circle which an outer periphery of the saw blade 5 will pass when the rotor 10 is rotated a full rotation, i.e. 360 degrees. In the embodiment shown, the outer periphery of the saw blade 5 will make a pass enabling cutting of wooden elements having a width between Wl and W2 and having a height between HI and H2.

In a possible embodiment, the saw blade has a diameter of approximately 400 mm. An axial displacement A (see Fig. 5) between a centre of the saw blade axle 6 and a centre of the rotor axle 13 is approximately 60 mm. In such embodiment, the outer periphery of the saw blade 5 will pass along a circle enabling cutting of wooden elements either having a width Wl of approximately 200 mm and a height HI of approximately 50 mm, or enabling cutting of wooden elements having a width W2 of approximately 250 mm and a height H2 of approximately 30 mm. Wooden elements having widths and heights proportional hereto may also be cut by the specific embodiment described.

Fig. 7 is a plane view of a drive mechanism of an apparatus according to an embodiment of the invention. The plane view is similar to the plane view shown in Fig. 5, however, the embodiment shown in Fig. 7 has a cardan shaft 31 with cardan joints 32, 33a for transferring torque from the drive shaft 17 to the axle 6 of the saw blade 5a. The saw blade 5a is shown in the first retracted position, and furthermore it is indicated that the saw blade may also be positioned in a second projecting position (indicated as saw blade 5b), and the cardan shaft and cardan joint 33a is accordingly shown in a corresponding second position (indicated as cardan joint 33b). During operation of the apparatus, the rotational speed of the drive shaft 17 may be above 1000 rotatons per minute (RPM), such as above 2000 RPM, such as above 3000 RPM, such as above 4000 RPM, such as 4450 RPM, such as above 5000 RPM. In the shown embodiment, the cardan shaft 31 may be angled more than 0 degrees with respect to the drive shaft 17 such as more than 5 degrees, such as more than 10 degrees, such as more than 15 degrees. The length of the cardan shaft 31, such as the length between cardan joints 32, 33a projected onto an axis being coaxial with the drive shaft 17, may be at least 200 mm, such as at least 300 mm, such as 350 mm, such as at least 400 mm. The distance 34 may be at least 350 mm, such as at least 450 mm, such as 500 mm, such as at least 550 mm.

Fig. 8 is a plane view of a drive mechanism of an apparatus according to an embodiment of the invention. The plane view is similar to the plane view shown in Fig. 5 and Fig. 7, however, the embodiment shown in Fig. 8 has a magnetic clutch 35 with clutch plates 36, 37a for transferring momentum from the drive shaft 17 to the axle 6 for the saw blade 5a. The saw blade 5a is shown in the first retracted position, and furthermore it is indicated that the saw blade may also be positioned in a second projecting position (indicated as saw blade 5b), and the clutch disk 37a is accordingly shown in a corresponding second position (indicated as clutch disc 37b). The magnetic clutch disc 37a is radially displaced with respect to clutch disc 36, corresponding to a radial displacement between the axle of the saw and the drive axle, the radial displacement being at least 1 mm, such as being at least 5 mm, such as being at least 10 mm, such as being at least 15 mm, such as being at least 20 mm, such as being at least 30 mm, such as being at least 50 mm, such as being at least 60 mm, such as being at least 75 mm, such as being at least 100 mm. In a particular embodiment one or both of clutch plates 36, 37a comprises one or more permanent magnets.

Fig. 9 shows schematic plane view figures illustrating some of the forces applied for different embodiments of the apparatus according to the invention.

Fig. 9A shows an embodiment corresponding to the embodiments shown in Figs. 5-6, and the figure shows a gear wheel 11 mounted on the axle 6 of the saw blade (saw blade not shown), and a gear wheel 12 mounted on the drive shaft 17 and rotor 10. By rotating the drive shaft 17 the gear wheel 12 on the drive shaft also rotates, and the gear wheel 12 exerts a force component 26 on gear wheel 11 mounted on the axle 6 of the saw blade. The force component 26 is applied a distance 30 away from the axis of the axle 6 of the saw blade in a direction orthogonal to a line from the axis of the axle 6 of the saw blade to the point of application of force component 26. Therefore, the force component 26 exerts a torque on the axle 6 of the saw blade, and the magnitude of the torque is given by the product of the distance 30 and the applied force component 26. The axle 6 of the saw blade is a rigid element, and therefore the force component 26 applied at the contact point between gear wheels 11, 12 is transmitted to the rotor in which the axle 6 of the saw blade is placed. Because the axle 6 of the saw blade is mounted in the rotor, the force component 26 is transmitted to the rotor 10, whereby a torque is exerted on the rotor 10. Because a torque is applied to the rotor 10, the rotor may rotate around a rotating axis of the rotor, said rotating axis in the embodiment shown being coaxial with the drive shaft 17.

In the embodiment illustrated in Fig . 9A, the rotation of the axle 6 of the saw blade and the rotation of the rotor 10 are linked . The torque generated on the rotor 10, when rotating the axle 6 of the saw blade as described above, may be sufficient for displacing the saw blade from the first position to the second position. If the rotation of the axle 6 of the saw blade and the rotation of the rotor 10 are linked, i.e., the mechanism for rotating the axle 6 of the saw blade also causes the rotor to rotate or vice versa, application of a torque on the rotor 10 by means of, e.g., a belt drive, e.g ., the one or more belts 23 shown in Fig. 5, may lead to a rotation of the rotor 10 which generates a torque on the gear wheel 11. The torque on the gear wheel 11 causes the axle 6 of the saw blade to rotate. Roation of the axle of saw blade may apply a torque on the drive shaft of the motor intended for driving the axle 6 of the saw blade, said torque applied on the drive shaft of the motor resulting in the motor to act as a generator in case the motor is an electrical motor.

Fig. 9B shows a plurality of force components 27 for generating the torque being applied to the axle 6 of the saw blade (saw blade not shown) in a plurality of points of application on the axle 6 of the saw blade. The points of application of the force components 27 are distributed around the axis of the axle 6 of the saw blade so that the plurality of force components 27 substantially, possibly completely, cancel out each other in terms of net force component in a direction being orthogonal to the axle of the saw blade and being orthogonal to a vector from the center of the rotor to the axis of the axle of the saw blade. In Fig. 9B, force components 27 may be applied by means of, e.g., a cardan shaft or a magnetic clutch (not shown), and the force components 27 are approximately equal in magnitude and directed in opposite directions, so that they substantially cancel out each other in terms of resulting force component on the axle 6 of the saw blade. There is no resulting force component on the axle 6 of the saw blade, and therefore there is no force component exerted on the rotor 10 and no torque is applied on the rotor 10. The rotor 10 will not rotate. However, both force components 27 contribute to the torque on the axle 6 of the saw blade and contribute to rotate the axle 6 of the saw blade in a clockwise direction as shown in Fig. 9B.

In Fig. 9B, two force components of equal magnitude and opposite directions are shown, each force component being orthogonal to a vector from the axis of the axle 6 of the saw blade to the point of application of the force components, however, any number more than one of applied force components is conceivable. The individual force components may each have any conceivable direction, and the individual force components may each be applied in any conceivable point of application.

In a particular embodiment of an apparatus, the plurality of force components results in a net force component, so that a force component is exerted on the rotor, which force component results in a torque on the rotor which is smaller than a torque necessary for displacing the saw blade from the first position to the second position, such as overcoming the torque applied on the rotor by gravity. Fig. 10 is a schematic plane view figure illustrating some of the force components applied for an embodiment where a force component 28 is applied on the axle 6 of the saw blade so as to generate a torque on the the axle 6 of the saw in order to rotate the axle 6 of the saw blade. The force component 28 is applied in a direction being substantially parallel with a line 29 from the rotational axis of the rotor 10 to the axis of the axle 6 of the saw blade. The force component applied on the rotor 10 by the axle 6 of the saw blade is in the same direction. The force component 28 results in no torque on the rotor 10, and the rotor will not be rotated by application of force component 28. The force component 28 could, in another embodiment, be directed downwards, and could in specific embodiments be applied by means of a belt or a chain.

Fig. 11 is a drawing showing another embodiment of the apparatus according to the invention, seen in a plane perpendicular to the saw blade. The plane view is similar to the plane view shown in Fig. 5, however, the embodiment shown in Fig. 11 furthermore comprises a braking mechanism being an air brake 38 which upon activation acts on the axle of the rotor. Thus the air brake 38 may serve to stop the rotation of the rotor and the corresponding planetary motion of the axle 6 of the saw blade around the axis of the rotor. One example where the air brake may be activated is upon an emergency stop where the first drive motor 20 (which is provided for driving the saw blade 5) stops and brakes the rotation of the saw blade 5 and axle 6 of the saw blade. Due to conservation of angular momentum the rotor 10 may start to rotate, however, this may be avoided by activating air brake 38. Fig. 11 furthermore shows torque limiter 39. In the particular embodiment, torque limiter 39 is embodied by a magnetic powder clutch.