Field of invention The present invention relates to an apparatus for guiding a piece of timber, especially a block, to a chipper canter, a sawing machine or the like machine tool for treating the timber, the apparatus comprising a conveyor disposed in front of the machine tool, and feed rolls and side rollers in front of and/or behind the machine tool.

Prior art

In a known apparatus (SE published patent application no.

346933), logs or blocks cut at two sides are orientated by orientating means moving symmetrically in relation to the center line of the conveyor and are fed in this orientated position to a sawing machine or a profile chipper connected to the apparatus. This centering positioning of the log or the like piece allows optimal use of wood in case the log is not crooked, in other words if the log is straight.

In order to achieve optimal use of wood when sawing crooked logs, the logs are usually sawn in such a way that the log is at first turned to direct its crooked portion upwards or downwards subsequent to which a so-called block with two opposite plane surfaces is formed of it by feeding it through a first sawing machine or a chipper canter. The crooked block can then be fed along a crooked path through a second chipper canter to form a square timber machined at all side surfaces.

Many kinds of devices are known for guiding a crooked piece of timber to a sawing machine or a profile chipper. US Fatent No. 4,440,203 discloses an apparatus for further machining of the remaining side surfaces of a straight or a crooked block by a chipper canter provided with two chipping discs. There are two consecutive guiding side roller pairs mounted on an articulated support arm in

front of the chipping discs, the side rollers being movable symmetrically in relation to the center line of the support arm, depending on the width of the block. Further, a guiding side roller pair is disposed in front of said first roller pairs, to receive the block and, together with the first roller pairs, to center the top of the block after which the rollers are drawn apart. There is a second pair of centering and guiding side rollers behind the chipping discs. When a crooked block moves the support arm to the right or the left, both the chipping discs move in the same direction without a change in the distance between them. When a straight block is treated the chipping discs remain in a centered position.

Finnish published patent application no. 76015 discloses an apparatus in which three consecutive lateral orientating units with two opposite orientating rollers are employed in front of a sawing machine or a profile chipper to orientate the top end of a log or the like introduced in the feeding point of the sawing machine or the profile chipper- The blades of the foremost orientating unit which is closest to the sawing machine or the profile chipper are movable both symmetrically and asymmetrically. The orientating unit in the middle is a measuring device which gives a signal indicating the degree of the lateral deviation of the log, the signal being used for guiding the foremost orientating unit. The apparatus allows a curved sawing line which at least to a certain extent follows the curved form of the log.

US Patent No. 4,127,044 discloses an apparatus for sawing a crooked block into boards in a frame saw in which the longitudinal configuration of one side surface, preferably the concave side surface, is sensed in front of the saw and lateral pressure is exerted on the same side surface by a resiliently pressing orientating roller in order to orientate the block in relation to the saw so as to saw the block parallel to the sensed configuration whereby the

orientating rollers can serve as the sensing means as well. If the width and the crooked form of the block are equal along the whole length of the block it is theoretically possible to obtain the desired result. In practice this is mostly not the case.

Finnish published patent application no. 68778 discloses an apparatus for sawing crooked logs, the apparatus being provided with two pairs of guide rollers disposed spaced apart, the rollers of which are forced to move symmetrically in pairs. A position sensor, for example a roller, is disposed in front of the guide roller pair, for sensing the side surface of the log and gives information on the crooked form of the log. At least one of the guide roller pairs is transferable in the direction transverse to the feed direction of the log which allows sawing along the crooked center line of the log.

Prior art devices can produce a crooked block of a crooked log or a straight block of a straight log but cannot produce a block of a desired crooked form of a crooked log.

Disclosure of invention The object of the present invention is to provide a simple and efficient device which allows machining a straight or a crooked block in a way which is not dependent on the configuration of the block.

It is also an object of the invention to provide a device for machining pieces of timber in a predetermined way.

This is achieved by the apparatus of the present invention which is characterized in that in front of the machine tool, there is a chain conveyor carrying the piece of timber; at least one press roll provided with means for pressing the piece of timber against the chain conveyor by means of said roll or for lifting the roll off from the

piece of timber; a feed roll disposed subsequent to the chain conveyor, which roll is provided with means for lifting or lowering said roll and which roll in its lower position is below the level of the chain conveyor and in its upper position above said level; a pair of side rollers the rollers of which are disposed each on different sides of the block and provided with means for pressing said rollers against opposite side of the block either in a manner centering the block or moving freely in the transverse direction; and that behind the machine tool, there is a second pair of side rollers the rollers of which are disposed each on different sides of the block and provided with means for pressing said rollers against the opposite sides of the block either in a manner centering the block or moving freely in transverse direction.

The apparatus preferably comprises a biconical roll, i.e., for example, a roll with reduced diameter center and wall portions diverging outwardly therefrom, provided with means for pressing the piece of timber by means of the biconical roll against a feed roll which is in its upper position-.

In an embodiment of the invention the rollers of the side roller pairs are mounted on bearings in turning arms coupled with each other via a connecting bar which comprises two piston-cylinder units which are rigidly connected to each other at their back walls and the piston arms of which are connected to the turning arms in such a way that one of the piston arms is connected to a turning arm or a member turning in a similar way, and the other piston arm is connected to the portion of a two-portioned turning arm, which is situated further away from the roller of the two-portioned arm, or to a member turning in a similar way.

Brief description of drawings

The details of the invention are disclosed, by way of example, in the following description and drawings which illustrate schematically an embodiment of the invention.

Figure 1 is a schematic side view of an apparatus according to the invention;

Figure 2 is a view of the apparatus of Fig. 1 viewed from above, Figure 3 is a section along line A - A of Figure 1,

Figure 4 is a view of the apparatus in the direction of arrow B in Figure 1; and

Figure 5 is an enlarged fragmentary illustration of details C and D in Figure 2.

Detailed description of drawings

In the apparatus illustrated in the drawings, a block 2a machined at two opposite side surfaces is formed into a four-edged block or a square timber 2b which is machined at all its four side surfaces by machining it further in a chipper canter 6 know per se and provided with two chipping discs 4. The chipping discs are movable in relation to the center line 8 of the chipper each with its own servo means 7.

In front of the chipper, a chain conveyor 10 is provided on which lies the block 2a to be introduced into the chipper canter. The chain conveyor comprises a plurality of chains 12 disposed side by side which preferably are provided with spikes for gripping the block while the block is pressed against the conveyor by means of press rolls 24, 26. A raisable and lowerable feed roll 14 is provided between the chain conveyor 10 and the chipper canter 6 which roll in its lower position is below the level of the conveyor and in its upper position above said level. The feed roll 14 is mounted on bearings in turning arms 16. The turning arms are moved by a piston-cylinder unit 18 which is filled with a pressure medium and are controlled by a

control unit 20. There is a second feed roll 22 behind the chipper canter 6 on which roll the machined block 2b lies.

Above the chain conveyor 10, there are press rolls 24 and 26 mounted on bearings in turning arms 28 and 30, which are moved by piston-cylinder units 32 and 34 which in turn are controllable by the control unit 20 in such a way that the rolls either press the block against the chain conveyor or do not touch the block.

A biconical roll 36 mounted on bearings in turning arms 38 is disposed above the feed roll 14, the turning arms being moved by a piston-cylinder unit 40 which are controlled by the control unit 20 to cause the roll to press the block against the feed roll 14 while the roll is in its upper position.

Above the feed roll 22, there is a press roll 42 mounted on bearings in turning arms 44 which are moved by a piston- cylinder unit 46. The control unit 20 controls the unit 46 which causes the roll to press the block against the roll or lifts the roll off from- the block.

At a suitable distance from the chipping discs 4 on the feed side of the chipper canter 6, a pair of side rollers 48 is provided the rollers 52 and 56 of which are disposed each on different sides of the block. Correspondingly, on the discharge side of the chipper canter at a suitable distance from the chipping discs, a pair of side rollers 50 is provided the rollers 54 and 58 of which are disposed each on different sides of the block. The side rollers 52, 54 and 56, 58 are connected in a way known per se to drive means which are not illustrated here. The rollers of both the side roller pairs are in the way illustrated in figure 5 mounted on bearings in turning arms 60 and 62 connected to each other by a connecting bar 64 which comprises two piston-cylinder units 66 and 68 rigidly

connected to each other at their back walls. The piston arms 70 and 72 of the piston-cylinder units are turnably or pivotally connected to turnings arms 60, 62 in such a way that one of the piston arms, 70, is connected through an articulated joint to one of the turning arms, 60, and the other piston arm, 72, is connected through an articulated joint to the arm .portion 63 of the two-portioned turning arm 62 which lie.s further away from the roll.

Further, the turning arms are interconnected by means of a piston-cylinder unit 74 a back wall 76 of which is pivotally or turnably connected to one of the turning arms, 62, and the piston arm 78 to the other arm, 60. The control unit 20 controls the piston-cylinder units 66, 68 and 74. It is clear that the turning arms can be connected by means of turning shafts to levers turning in the same direction as the turning arms whereby the piston-cylinder units can be connected to these levers.

The location of the articulated points of the connecting bar and the dimensions of the piston-cylinder unit are chosen such that when the piston 80 of the cylinder 66 is in its outmost position and the piston 82 of the cylinder 68 in its innermost position as illustrated in the figure, and the cylinders are pressurized so that in effect they form a rigid bar, the side rollers 52, 54 and 56, 58 are moved symmetrically in relation to the center line 8 by the piston-cylinder unit 74.

When it is desired that the side rollers 52, 54 and 56, 58 can move to an eccentric position in lateral direction the pressure is released from the cylinders 66 and 68 which results in the piston-cylinder unit 74 pulling the rollers to the surface of the block. The rollers can thus feed the block but not guide it in the lateral direction. The function of the piston-cylinder units is floating.

The apparatus is provided with a necessary number of detectors the operation of which is preferably not based on contact, for example optical detectors, which detect passing of the leading end or the rear end of the block and give a signal to the control unit 20.

The apparatus is constructed and controlled to function in the following ways; the chipping discs 4 being set to a predetermined setting symmetrically in relation to the center line 8:-

A. Straight sawing

The block 2 is pressed by means of press rolls 24 and 26 against the chain conveyor 12 whereby the chain conveyor 10 guides the block. The side rollers 52 and 56 in front of the chipper canter press the sides of the unmachiαed blocks but do not guide the block. The side rollers 54 and 58 behind the chipper canter press the machined sides of the block and guide and center the block. The biconical roll 36 has been lifted and the feed roll 14 lowered.

B. Acute crooked sawing

The press rolls 24 and 26 have been lifted up. The biconical roll 36 presses the block against the feed roll 14 which has been raised. The chain conveyor does not guide the block. The side rollers 52 and 56 in front of the chipper canter press, guide and center the block. The side rollers 54 and 58 behind the chipper canter press the block but do not guide it.

C. Limited crooked sawing

The press rolls 24 and 26 have been raised. The biconical roll 36 and the feed roll 14 are controlled to operate for a short while in the middle region of the block. The side rollers 52 and 56 in front of the chipper canter press the block but do not guide it. Depending on the desired crookedness, the side rollers 54 and 58 behind the chipper canter can be employed to

a) at first press and center the block and after that press the block without guiding it; b) press and center the block all the time; or c) press the block all the time without guiding it.

The invention makes possible machining the sides of a crooked block in a way programmed in the control unit, corresponding to the crookedness of the block or deviating from it.

It is clear that the embodiment of the invention described above and illustrated in the figures is an example, only, of the way the invention can be carried out and that the invention can be modified within the scope of protection defined by the- patent claims. Thus, for example, the chipping discs can be replaced by sawing blades.