WO2009109704A2

WO2009109704A2 - Machine tool, slat conveyor suitable for machine tools and method for machining an object with a machine tool

Info

Publication number: WO2009109704A2
Application number: PCT/FI2009/050182
Authority: WO
Inventors: Ismo Suontausta
Original assignee: Iomus Oy
Priority date: 2008-03-07
Filing date: 2009-03-06
Publication date: 2009-09-11
Also published as: FI20085215A0; WO2009109704A3

Abstract

The machine tool has at least one machining device (20) for machining the object (100) to be machined and at least one slat conveyor for moving and supporting the object to be machined during the machining. The machining device of the machine tool can for example be a sawing device, which comprises at least one blade (23) for cutting the object to be machined. The machining device can be moved on guide tracks (24) back and forth in the conveying direction of the object to be machined, which makes possible the machining during the conveying movement of the object to be machined. The slats (38) of the slat conveyor form a support surface (42), whereon the objects to be machined are during the machining. The conveyor comprises a support beam (52) for supporting below the second ends of the slats. The support beam has an outlet opening (58) for guiding the second end of the slat below the support beam and a return opening (68) for guiding the end of the slat back above the support beam. The end of the slat can thus be moved temporarily below the level of the support surface, whereby a recess (66) is formed in the support surface, which recess functions as a machining position, which recess is able to receive the blade of the machining device, which blade reaches below the level of the support surface. The cross- section of the slats of the slat conveyor is preferably in the shape of the letter L.

Description

Machine tool, slat conveyor suitable for machine tools and method for machining an object with a machine tool

TECHNICAL FIELD OF THE INVENTION The invention relates to a machine tool, which has at least one machining device for machining an object to be machined and at least one slat conveyor for moving and supporting the object to be machined during the machining, which slat conveyor has a support surface made up of several adjacent, interconnected slats. The invention also relates to a slat conveyor suitable especially for machine tools and a method for machining an elongated object with a machine tool.

BACKGROUND OF THE INVENTION

A typical machine tool comprises at least one machining device for machining an object and a conveyor for moving the object to be machined into the reach of the machining device. The machining means can for example be a cutting device, such as a saw, a milling machine, a drill or a grinder. The material of the objects to be machined can for example be wood, metal, plastic or some other equivalent material. The conveyor can be for example a belt or slat conveyor.

For example in the manufacturing of different wooden products it is typical that parts and pieces, which are needed in manufacturing the final product, are produced by sawing from long timber pieces, such as planks, battens, boards and mouldings. The long timber pieces are conveyed with a conveyor into the reach of the saw of the machine tool and cut with the saw into suitable sized pieces. After the sawing the conveyor conveys the sawed pieces onwards for further processing.

In the cut-off sawing of timber pieces the saw blade runs through the entire wood cross-section and reaches slightly below the level of the underside of the piece. Because the timber pieces are on the conveyor for the whole duration of the sawing procedure, the structure of the conveyor needs to be such as to make possible the reaching of the saw blade below the support surface of the conveyor. Known machine tool conveyors use among others belt conveyors, which at regular intervals have points of discontinuity, at which points the sawing procedure can be done without damaging the belt. It is further known to use roller tracks as a conveyor, constructed of subsequently placed rollers, whereby the sawing procedure can be done in the area between the rollers. Such conveyor solutions can however be used only in connection with sawing devices, where the timber piece to be cut is stopped in its place for the duration of the sawing procedure. It is clear that the cutting of timber pieces is slow with such machine tools, wherefore the performance of the machine tools is relatively small.

A sawing device is known from publication WO 98/13165, where the saw is supported in a moveable manner on guide tracks. The saw is moved with the aid of an actuator along the guide tracks with the same speed and in the same direction as the wood piece to be sawed on the conveyor moves. In this way the cut-off sawing of the wood piece can be done without halting the piece to be cut for the duration of the sawing, which remarkably speeds up the sawing procedure. The speeding up of the sawing has an especially large significance in situations, where a long timber piece is made into several short pieces by sawing. Such a sawing operation is typical for example in the furniture or parquet industry and in the manufacturing of finger joints. The problem with the device described in publication WO 98/13165 is that it is badly suited for manufacturing wood pieces of different length. The publication does not describe in more detail the structure of the conveyor belonging to the device, but it is clear that the conveyor must have a point of discontinuity, which enables the penetration of the saw blade, at each sawing point. Thus, for example with a device equipped with a slat conveyor, the cut-off sawing can be done only at the gap between the slats, which restricts the possibility of manufacturing pieces of different length.

A machining device is known from publication WO 03/092943, which machining device comprises at least one machining means, which is moveable on guide tracks, at least one machining conveyor for moving and supporting an object to be machined in the machining area and at least one transfer conveyor for transferring the object to be machined to the machining conveyor. The machining conveyor has at least one recess, which is arranged to function as a machining position, i.e. as the position, where the machining means performs the machining procedure, such as the cut-off sawing. In this device the conveying speeds of the machining conveyor and the transfer conveyor are adjusted separately, so that the recess in the machining conveyor settles in the desired machining position, e.g. the sawing point. The device makes possible the sawing of pieces of different length from a long timber piece. A disadvantage of the device is however that the conveyor arrangement constructed of two separate conveyors is rather complicated. Getting the machining conveyor and the machining means to function in a synchronized manner further requires a precise controlling equipment. In practise the problems relating to the controlling of the machining means and conveyor restrict the feeding rate of the timber piece and thus lower the performance of the device.

OBJECTS OF THE INVENTION

The object of the invention is to provide a machine tool, a slat conveyor suitable especially for machine tools and a method for machining an elongated object, with which the disadvantages and flaws relating to the prior art can be reduced.

The objects of the invention are obtained with a machine tool, a slat conveyor and a method, which are characterized in what is presented in the independent claims. Some advantageous embodiments of the invention are presented in the dependent claims.

DESCRIPTION OF THE INVENTION

Typically, the machine tool according to the invention has at least one machining device for machining an object to be machined and at least one slat conveyor for moving and supporting the object to be machined during the machining. The slat conveyor has several adjacent, interconnected slats, the upwards pointing surfaces of which form the support surface of the conveyor, whereon the objects to be machined are during the machining. The machine tool has means for moving a single slat of the slat conveyor temporarily at least partly below the level of the support surface, whereby a recess is formed in the support surface. This recess functions as a machining position, where the machining with the machining device is performed. The forming of the recess in the support surface is important because it makes possible the reaching of the machining device completely through the cross-section of the object to be machined, i.e. the machining device can reach below the level of the support surface of the slat conveyor. Due to the formed recess, the machining device can however not reach to touch the slat conveyor, so the conveyor is not damaged during the machining procedure. The recess is formed in the support surface only temporarily for performing the machining procedure. After the machining procedure the slat returns to its original height level. In an advantageous embodiment of the machine tool according to the invention the machining device is a sawing device, which comprises at least one blade unit for cutting the object to be machined. Cut-off sawings are thus done with the machine tool, with which sawings the elongated piece is cut into shorter pieces of a desired length. The sawing direction is preferably essentially parallel with the longitudinal direction of the slat. In other words the sawing direction and the conveying direction of the object to be machined are essentially perpendicular to each other.

A second advantageous embodiment of the machine tool according to the invention comprises guide tracks, whereon said at least one machining device is supported. The machining device can be moved back and forth on guide tracks in the conveying direction of the object to be machined, which makes possible the machining during the conveying movement of the object to be machined. The slat conveyor does thus not need to be halted for the duration of the machining of the object. If the machine tool has several machining devices, one machining device can be in movement according to the movement direction of the conveyor, performing a machining procedure, and the rest of the machining devices are in movement in the opposite direction, returning to the start of the machining area.

In a third advantageous embodiment of the machine tool according to the invention said slat conveyor comprises at least one second support beam for supporting below the second ends of the slats. This second support beam has at least one outlet opening for guiding the second end of the slat below the second support beam and at least one return opening for guiding the second end of the slat back above the support beam. It preferably further comprises means, such as a deflection disc rotatable with a motor, for forcing the second end of the slat into the outlet opening.

A fourth advantageous embodiment of the machine tool according to the invention comprises a control unit for controlling the motors and actuators of the machine tool and at least one detector in connection with the control unit for determining the machining position. The control unit and the detector connected thereto make possible the automatic determining of the machining positions. The machining position may for example be the starting end of the object to be machined, a marking or flaw in the object to be machined or a distance from the previous machining position, determined by measuring. The control unit may for example be a computer, into the memory of which has been loaded a computer program, which takes care of the control logistics of the machine tool. The computer gives control commands to the motors and actuators based on the data detected by the detector and/or inputted into the computer.

In a fifth advantageous embodiment of the machine tool according to the invention the slats of said slat conveyor have a cross-section in the shape of a letter L, i.e. they have a horizontal base part and a protruding part, which continues upwards from the base part. The upwards pointing end surfaces of the protruding part form the support surface of the conveyor. A gap is left between the protruding parts of adjacent slats, so the support surface has recesses at regular intervals, which recesses can receive the machining device, such as the sawing device's blade, which reaches below the level of the support surface in connection with the machining procedure. In this embodiment, the second end of the slat needs to be moved downwards from the level of the support surface only when the machining position of the machine tool is situated at the protruding part of the slat.

The slat conveyor according to the invention, which is suitable especially for machine tools, has a support surface for objects to be conveyed. The support surface is made up of several adjacent interconnected slats. The slat conveyor is characterized in that it comprises means for moving a single slat temporarily at least partly below the level of the support surface, in order to form a recess in the support surface.

An advantageous embodiment of the slat conveyor according to the invention comprises at least one second support beam for supporting below the second ends of the slats. This second support beam has at least one outlet opening for guiding the second end of the slat below the second support beam and at least one return opening for guiding the second end of the slat back above the support beam. The outlet opening and return opening preferably have a slanting end surface, which functions as a guide, where one of the ends of the slat is supported while the other end of the slat moves from one surface of the support beam to the other surface.

A second advantageous embodiment of the slat conveyor according to the invention further comprises means, such as a deflection disc rotatable with a motor, for forcing the second end of the slat into the outlet opening.

A third advantageous embodiment of the slat conveyor according to the invention further comprises an intermediate support, which has a sliding surface for forming a support below the slat by the outlet opening. In a fourth advantageous embodiment of the slat conveyor according to the invention the slats have a cross-section in the shape of a letter L.

A fifth advantageous embodiment of the slat conveyor according to the invention comprises a first end roll and a second end roll and at least one drive chain running around the end rolls, onto which the first ends of the slats are attached. The conveyor further has a motor for rotating the first end roll, which puts the upper surface of the slat conveyor in a translational motion.

In a method according to the invention an elongated object, such as a long timber piece, is machined with a machine tool, which has at least one machining device for machining the object to be machined and at least one slat conveyor for moving and supporting the object to be machined during the machining. The slat conveyor has several adjacent, interconnected slats, the upwards pointing surfaces of which form the support surface, whereon the object to be machined is during the machining procedure. In the method a slat of the slat conveyor is moved temporarily at least partly below the level of the support surface of the slat conveyor. A recess is thus formed in the support surface of the slat conveyor, which recess functions as a machining position, i.e. as the position, where the machining device performs the machining procedure. The recess makes it possible for the machining device or some part of it to reach below the level of the support surface of the conveyor when performing the procedure, without damaging the conveyor. The recess preferably comprises only one slat, which is moved at least partly below the level of the support surface. The recess may also comprise several slats, for example two, three, four or five adjacent slats.

In an advantageous embodiment of the method according to the invention the machining device is a sawing device, which comprises at least one blade, with which the cut-off sawing of the object to be machined is done.

In a second advantageous embodiment of the method according to the invention the machining device is moved in the conveying direction of the object to be machined and the machining of the object is performed during the conveying movement of the object to be machined. The object to be machined is thus not halted for the duration of the machining.

In a third advantageous embodiment of the method according to the invention said slat conveyor comprises at least one second support beam for supporting below the second ends of the slats. Said recess, which functions as a machining position, is formed by guiding the second end of the slat temporarily below the second support beam. After the performing of the machining procedure, the second end of the slat is led back above the support beam.

In a fourth advantageous embodiment of the method according to the invention the machining position of the object to be machined is first determined and a recess is formed in the slat conveyor at the determined machining position. The machining position may for example be the end of the object to be machined, a marking in the object to be machined or a removable flaw in the object to be machined. The machining position can be determined by detecting one of the above-mentioned positions in the object to be machined with the aid of a detector or by measuring the distance from the previous machining position.

The advantage with the method and machine tool according to the invention is that a greater machining speed is achieved with them compared to known solutions. The operating principle of the machine tool is simple, so no complicated controlling systems are needed for controlling its function.

Curved objects can also be machined with the machine tool according to the invention. Due to the reliable support of the object to be machined, the object does not need to be separately supported with gripping means at the machining position, so no excess marks are left on the surface of the object.

An advantage of the slat conveyor according to the invention is that its structure is simple and its manufacturing costs are inexpensive. Due to its simple structure it is also reliable and its need for maintenance is slight.

BRIEF DESCRIPTION OF THE DRAWING In the following, the invention will be described in detail. In the description, reference is made to the appended drawing, in which

Fig. 1 shows as an example a machine tool according to the invention seen from the side,

Fig. 2a shows as an example a slat conveyor according to the invention seen from the side,

Fig. 2b shows a cross-section of the slat conveyor of Figure 2a and Fig. 3 shows as an example a longitudinal cross-section of a slat conveyor according to the invention.

DETAILED DESCRIPTION OF THE DRAWING

5 In Figure 1 is shown as an example a machine tool according to the invention seen from the side. The machine tool portrayed in the figure is used to cut elongated timber pieces, such as planks, battens, boards and mouldings, into suitable pieces of a fixed length. The machining device 20 of the machine tool is a sawing device, which has two blade units 22, which are supported on guide tracks

10_. 24 and are moveable along them. Both blade units comprise a blade 23, which performs the cut-off sawing, and a motor, which rotates the blade (the motor is not shown in the figure). The guide tracks are attached at their first end to a first frame 26 and at their second end to a second frame 27. The frames are attached at their centre point on bearings to the body of the machine tool. The frames and guide

15 tracks make up the support structure of the blade units, which support structure can be rotated around the rotation axis, which runs through the bearing points of the frames, so that the blade of each blade unit comes in its turn to a machining distance from the object 100 to be machined. The sawing device shown in Figure 1 has two blade units, but it is clear that there can be only one or more than two 0 blade units. Sawing devices, which comprise moving blade units, are as such know in the prior art, among other from the publication WO 98/13165, so their structure will not be described further in this context.

The first and second frame outline between them a machining area 32, within which the blade units can move back and forth in the direction of the guide tracks. 5 The cutting of the timber piece takes place when the piece is in this area. At the machining area there is a machining conveyor 30, which functions as a base, which supports the object to be machined, during the machining. In the transfer direction of the timber there is in front of the machining conveyor a first transfer conveyor 34, which conveys the objects to be machined to the machining 0 conveyor, and in the transfer direction there is behind the machining conveyor a second transfer conveyor 36, which conveys the cut timber pieces away from the machining conveyor for further processing.

The type of the machining conveyor shown in Figure 1 is a so-called slat conveyor, which is made up of several adjacently placed elongated slats 38. The slats are connected to each other with two unbroken, continuous chains, which run around a first end roll 40 and second end roll 41 in the ends of the conveyor. The upwards pointing surfaces of the slats form a support surface 42, whereon the object 100 to be machined rests during the cut-off sawing.

The first transfer conveyor 34 comprises a first belt conveyor 44 and two second belt conveyors 45, which are placed above and are essentially parallel with the first belt conveyor. Belt conveyors are generally known transfer devices, so their structure will not be described further in this context. The wood piece to be machined is placed on the first belt conveyor, whereby it moves conveyed by the belt towards the machining conveyor 30. The task of the second conveyors is to press the objects to be machined against the first belt conveyor with suitable force. The distance between the first belt conveyor and the second belt conveyors is adjusted to be suitable based on the cross-section measurements of the wood pieces to be conveyed on the belt. The first and second belt conveyors are rotated with a rotation motor (not shown in the figures). The rotation speed of the rotation motor can be adjusted in order to set a suitable transfer speed for the wood pieces. The second transfer conveyor 36, situated behind the machining conveyor, is structurally the same as the first transfer conveyor. In the embodiment shown in Figure 1 the second belt conveyor comprises a first belt conveyor 44', which makes up the actual conveying surface, and a second belt conveyor 45', which is situated above it. Instead of second belt conveyors, the transfer conveyor may use roller plungers or sliding plungers, wherewith the desired amount of downwards force is produced onto the wood piece to be machined. In Figure 1 the length of the machining conveyor is essentially the length of the machining area, and the first transfer conveyor is situated in front of it and the second transfer conveyor behind it. The machining conveyor can however also be longer than the width of the machining area, whereby it extends at its one end or both ends outside the machining area. The length of the first and/or second transfer conveyor can thus be shorter. In extreme cases the machining conveyor can extend so far outside the machining area that it may replace one or both of the belt conveyors 44, 44'. The second belt conveyors, roller plungers or sliding plungers, which press the object to be machined downwards, are thus situated above the machining conveyor 30.

In Figure 2a is shown as an example a machining conveyor of a machine tool according to the invention as a simplified side view. Figure 2b shows the machining conveyor of Figure 2a as a cross-section seen from the sectional plane A-A. The machining conveyor according to the invention is a so-called slat conveyor, which has several adjacently placed elongated slats 38. The upper surfaces of the upper slats 38 of the slat conveyor make up the support surface 42, whereon the objects 100 to be machined with the machine tool are placed. The machine tool has a machining area 32, which has two blade units 22, which are moveable on guide tracks. The blade units have blades 23 for performing the cut-off sawing. Only the blade units of the machine tool have been shown, in order to preserve the clarity of the figure. The slat conveyor shown in Figure 2a and 2b is so long that it extends at its both ends clearly outside the machining area. In the area between the first end roll 40 and the machining area 32 of the slat conveyor there are plungers, wherewith the timber pieces on the slat conveyor are pressed with a desired force against the support surface 42. In Figure 2a is shown as an example a belt plunger 74 and a roller plunger 75, but the use of other kinds of plungers is also possible.

The slats are connected to each other with two adjacent, continuous, ring-like drive chains, with a first drive chain 46 and a second drive chain 47, which run around the first end roll 40 and the second end roll 41 in the ends of the conveyor (Figure 2b). A motor (the motor is not shown in the figures) is connected to the first end roll, with the aid of which motor the first roll is rotated around its rotation axis in order to set the upper surface of the conveyor in a translational motion. The rotation speed of the motor can be adjusted, so the conveying speed of the slat conveyor can be adjusted simply by altering the rotation speed of the motor. The first drive chain is situated near the first edge of the slat conveyor, i.e. the chain is attached near the first ends of the individual slats. The second chain is situated at a distance from the first chain, beside the first chain and parallel with it. The distance from the second chain to the second end of the slat is clearly larger than the distance of the first chain from the first end of the slat, i.e. both drive chains are situated in the vicinity of the first edge of the conveyor. In the first edge of the conveyor, beneath the slats, which make up the support surface 42, there is a first support beam 48, along the grooves 50 in which the first and second drive chain moves. In the second edge of the slat conveyor, near the second ends of the slats, there is a second support beam 52, which makes up the support underneath the second ends of the slats. When the conveyor is in operation, the second ends of the slats slide along the upper surface of the second support beam. The second support beam 52 of the conveyor has an outlet opening 58, which is slightly larger than the width of the slat, in the area between the first end roll 40 and the machining area 32, which outlet opening extends from the upper surface of the support beam to its lower surface. The end surface 60 of the outlet opening, i.e. the wall of the gap, which is closest to the second end roll 41 , is formed to be a downwards slanting surface, i.e. the angle formed by the end surface and the upper surface of the support beam is a sharp angle. By the outlet opening the second support beam thus does not have an upper surface to support the second end of the slat. By the outlet opening, between the first and second support beam, there is however an intermediate support 54, the upwards pointing surface of which has a flexible, compressible sliding surface 56 (Figure 2b), which comes in contact with the lower surface of the slats 38. By the outlet opening the intermediate support and the sliding surface thus form a support surface, which supports the slat from below. By the outlet opening, above the support surface of the conveyor, there is a deflection disc 62, which is connected via an axis 64 to a motor 65, preferably a servomotor. The rim of the deflection disc has a first edge surface part, which is at a constant distance from the axis 64, and a second edge surface part, the distance of which grows in a spiral manner from the axis. The deflection disc is situated above the second end of the slat so that the second end of the slat can fit to pass underneath the first edge surface part. When the deflection disc 62 rotates around the axis 64, its second edge surface part comes in contact with the upper surface of the slat 38 and presses the second end of the slat downwards, whereby the second end of the slat is pushed into the outlet opening 58 of the second support beam 52.

Each slat has a hinge link 72 in the area between the second drive chain 47 and the intermediate support 54, which hinge link makes possible the rotation of the second end of the slat downwards around the hinge link, when a downwards directed force is applied to the second end of the slat. Alternatively the slats can be formed to be flexible parts, which function like leaf springs. The second ends of the slats thus bend downwards due to the downwards working force, even if there is no actual hinge link in the slats. As the second ends of the slats bend downwards the sliding surface 56 of the intermediate support 54 is compressed, which makes possible the moving downwards of the second end of the slat. When the slat conveyor is in operation, the upper slats, which make up the support surface of the conveyor, move towards the second end roll 41. The second ends of the slat, which have been forced into the outlet opening 58, are thus pushed, directed by the slanting end surface 60, below the second support beam and move towards the second end roll below the support beam. A recess 66 is thus formed on the support surface of the slat conveyor, at the position of the slat, which was forced underneath the support beam, which recess has the width of one slat, by which recess the cut-off sawing of the object 100 to be machined on the conveyor can be done in the machining area 32. In order for the cut-off sawing to be successful and to achieve a clean saw cut it is important that the blade 23 of the blade unit 22 cuts through the entire cross-section of the object to be machined, i.e. the edge of the blade reaches clearly below the level of the support surface 42 determined by the upper surfaces of the slats. The recess 66, which has been formed in the slat conveyor, is so deep that it is able to receive the blade 23, which extends below the support surface, so the cutting procedure performed by the blade unit does not damage the structures of the slat conveyor. In the second end of the slats there is a protruding support 76 (Figure 2b), against which the object to be machined is supported at its edge during the cut-off sawing. Due to the support no plungers are necessarily needed in the machining area for pushing the object to be machined against the slat conveyor.

The machine tool according to the invention further comprises a control unit 80, which is connected in a known manner to the motors and actuators of the machine tool for controlling their function. With the aid of the control unit the machining positions of the object to be machined on the machining conveyor are determined automatically. In connection with the slat conveyor, by the deflection disc 62 and the outlet opening 58, has been arranged at least one detector 82, which is functionally connected to the control unit, which detector detects the end of the object to be machined on the conveyor, i.e. the starting point of the object, and a cutting mark made in the object to be machined, such as a fluorine- containing line. Instead of one detector, the machine tool may also have several different detectors for detecting different kinds of detection markings. When the control unit detects with the aid of the detector the end of the object to be machined, it forms in this position of the object a first machining position, where a machining procedure is performed. By the end of the object this procedure is a cut-off sawing, wherewith a possibly faulty end surface of the object is rectified. In a corresponding manner, when the control unit detects with the aid of the detector a cutting mark in the object to be machined, such as a fluorine-containing mark, it forms in this position a machining position. The later machining positions, which come after the first machining position, can also be determined by measuring from the first machining position. The control unit is able to calculate the location of the next machining position based on the previous machining position, the measuring data inputted into the control unit and the conveying speed of the conveyor.

When the control unit has determined the machining position, it controls the motor to rotate the rotation disc one turn around the axis 64, whereby the second end of the slat 38 at the machining position is pushed into the outlet opening 58. A recess 66 is thus formed in the slat conveyor at the machining position, which recess makes possible the machining, i.e. the cut-off sawing, of the object to be machined without damaging the slat conveyor. The plungers 74 and 75 prevent the timber piece from moving in relation to the support surface 42 of the slat conveyor, so the machining position stays in the area of the recess 66 as the timber piece moves through the machining area 32.

In the area between the machining area and the second end roll 41 there is a return opening 68, the end surface 70 of which is an upwards slanting surface, i.e. the angle between the lower surface of the second support beam 52 and the end surface 70 is sharp. By the return opening, the upper support surface, which influences the second end of the slat, goes away, whereby the second end of the slat rises upwards into the return opening. In the return opening the slanting end surface 70 forces the end of the moving slat to rise upwards, until the end of the slat is at the level of the support surface 42 of the conveyor.

The sawing procedures done with the sawing device can for example be fixed size sawings, marking sawings, sawings for removing flaws or optimized sawings. In fixed size sawing, information is inputted into the control unit 80 of the machine tool about the first cutting position and a fixed measure, whereafter as many pieces of the fixed length as possible are separated from the timber piece by sawing. In marking sawing the sawing positions are marked in the object to be sawed for example with fluorine lines. The detector in the machine tool detects the marking lines and performs the cut-off sawing at the marking line. In flaw removal sawing flaws in the timber piece, such as branch sites, are removed. The detection and marking of flaws is done with a separate flaw detection device, which does not belong to the machine tool. In optimized sawing the cutting positions in the timber are first determined with a device outside the machine tool, such as a production control system, whereafter the cut-off sawings are done with the machine tool at the determined machining positions. In the embodiment of the invention shown in Figures 2a and 2b a downwards directed force is directed onto the second end of the slat with the aid of a deflection disc rotated by a motor. For a person skilled in the art it is clear that also other means and actuators can be used in the invention for moving the second end of the slat into the outlet opening and further onto the lower surface of the second support beam. Pneumatic devices are for example such possible actuators. In the advantageous embodiment of the slat conveyor presented in Figure 2a has been shown only one outlet opening 58. The slat conveyor can however also have more than one outlet opening, whereby the outlet openings are situated at a distance from each other in the area between the machining area and the first end roll and in connection with each outlet opening there is an own actuator for moving the end of the slat into the outlet opening. By using several outlet openings the speed of the slat conveyor can be increased.

In Figure 3 is shown as an example an advantageous embodiment of a slat conveyor according to the invention as a longitudinal cross-section of the conveyor. The figure shows a part of the upper surface of the slat conveyor, i.e. of the surface, whereon the objects to be machined, which are conveyed with the conveyor, are placed. The cross-sectional shape of the slats 38 is in the shape of a letter L, i.e. they have a horizontal base part 39 and a protruding part 37, which continues upwards from the edge of the base part. In this embodiment the upwards pointing end surfaces of the protruding part form the support surface 42, whereon the objects to be conveyed on the slat conveyor are placed. A gap is left between the protruding parts of adjacent slats, i.e. the support surface is not even, but it has recesses 66 at regular intervals, which recesses are able to receive the blade 23, which reaches below the level of the support surface in connection with cut-off sawing. In this embodiment, the second end of the slat needs to be moved downwards from the level of the support surface only when the machining position of the machine tools is situated at the protruding part of a slat. When the machining position is not at a protruding part, the machining procedure can be performed without altering the position of the slat. By selecting the dimensions of the base part 39 and the protruding part 37 to be suitable, the need to move the slats can be reduced by up to 60% compared to slats, which have a rectangular cross-section.

Some advantageous embodiments of the machine tool, slat conveyor and method according to the invention have been described above. The invention is not limited to the solutions just described, but the inventive idea can be applied in numerous ways within the scope of the claims.

Claims

1. A machine tool, which has at least one machining device (20) for machining an object (100) to be machined and at least one slat conveyor (30) for moving and supporting the object to be machined during the machining, which slat conveyor has a support surface (42) made up of several adjacent, interconnected slats (38), characterized in that it comprises means for moving a single slat temporarily at least partly below the level of the support surface in order to form a recess (66) in the support surface (42), which recess functions as a machining position.

2. The machine tool according to claim 1 , characterized in that said machining device (20) is a sawing device, which comprises at least one blade (23) for cutting the object to be machined.

3. The machine tool according to claim 1 or 2, characterized in that it comprises guide tracks (24), whereon said machining device (20) is moveably supported, for moving the machining device in the conveying direction of the object (100) to be machined in order to carry out the machining during the conveying movement of the object to be machined.

4. The machine tool according to any of claims 1-3, characterized in that said slat conveyor (30) comprises at least one second support beam (52) for the supporting below the second ends of the slats, which second support beam has at least one outlet opening (58) for guiding the second end of the slat below the second support beam and at least one return opening (68) for guiding the second end of the slat back above the support beam.

5. The machine tool according to claim 4, characterized in that it further comprises means, such as a deflection disc (62) rotated by a motor (65), for forcing the second end of the slat (38) into the outlet opening (58).

6. The machine tool according to any of claims 1-5, characterized in that it comprises a control unit (80) for controlling the motors and actuators of the machine tool and at least one detector (82) in connection with the control unit for determining the machining position.

7. The machine tool according to any of claims 1-6, characterized in that the cross-section of the slats (38) of said slat conveyor is in the form of the letter L.

8. A slat conveyor, which comprises a support surface (42) for objects (100) to be conveyed, which support surface is made up of several adjacent, interconnected slats (38), characterized in that it comprises means for moving a single slat temporarily at least partly below the level of the support surface in order to form a recess (66) in the support surface (42).

9. The slat conveyor according to claim 8, characterized in that it comprises at least one second support beam (52) for the supporting below the second ends of the slats, which second support beam has at least one outlet opening (58) for guiding the second end of the slat below the second support beam and at least one return opening (68) for guiding the second end of the slat back above the support beam.

10. The slat conveyor according to claim 9, characterized in that the outlet opening (58) and return opening (68) have a slanting end surface (60, 70).

11. The slat conveyor according to claim 9 or 10, characterized in that it further comprises means, such as a deflection disc (62) rotated by a motor (65), for forcing the second end of the slat (38) into the outlet opening (58).

12. The slat conveyor according to any of claims 9-11 , characterized in that it further comprises an intermediate support (54), which has a sliding surface (56) for forming a support below the slat (38) by the outlet opening (58).

13. The slat conveyor according to any of claims 8-12, characterized in that the cross-section of the slats (38) is in the form of the letter L.

14. The slat conveyor according to any of claims 8-13, characterized in that it comprises a first end roll (40) and a second end roll (41), at least one drive chain (46, 47) running around the end rolls, onto which drive chain the first ends of the slats (38) are attached, and a motor for rotating the first end roll.

15. A method for machining an elongated object with a machine tool, which has at least one machining device (20) for machining an object (100) to be machined and at least one slat conveyor (30) for moving and supporting the object to be machined during the machining, which slat conveyor has a support surface (42) made up of several adjacent, interconnected slats (38), characterized in that in the method a slat of the slat conveyor is moved temporarily at least partly below the level of the support surface in order to form a recess (66) in the support surface (42), which recess functions as a machining position.

16. The method according to claim 15, characterized in that said machining device (20) is a sawing device, which comprises at least one blade (23), wherewith the cut-off sawing of the object to be machined is done.

17. The method according to claim 15 or 16, characterized in that the machining device (20) is moved in the conveying direction of the object (100) to be machined and the machining is carried out during the conveying movement of the object to be machined.

18. The method according to any of claims 15-17, characterized in that said slat conveyor (30) comprises at least one second support beam (52) for the supporting below the second ends of the slats (38), whereby said recess (66), which functions as a machining position, is formed by guiding the second end of the slat temporarily below the second support beam.

19. The method according to any of claims 15-18, characterized in that in the method the machining position of the object (100) to be machined is first determined and the recess (66) is formed in the slat conveyor (30) at the determined machining position.