GB2045679A - An apparatus arranged for centering logs, blocks or like workpieces relative to a given desired centering line. - Google Patents

Abstract

Each of a pair of centering means (6, 7) is provided with two or more centering elements (11) bearing against the workpiece (2), each element being resiliently displaceable laterally relative to the centering line so as to be able to yield when coming into contact with an outwardly projecting knot (14) or the like on the workpiece. In this way, the presence of knots and the like will not disturb the correct centering of the workpiece. The centering element may comprise coil springs or spring-biassed lines which are arranged substantially vertically one after the other along the centering line. Alternatively the elements may comprise two pairs of arms (19, 20) and (21, 22), one arm of each pair being chamfered and arranged to cooperate with similar chamfers on the ends of spring biassed locking members (25). In another embodiment the elements may comprise two pairs of abutments 101 on each side of the workpiece, each pair being pivotally connected to a yoke 97 pivotally mounted on a centering arm 94, 95. <IMAGE>

Description

SPECIFICATION Apparatus for aligning logs, blocks and like workpieces for passage through a working machine, and for feeding said workpieces through said machine The present invention relates to an apparatus on the infeed side of a saw or like working machine for centering and aligning elongate workpieces such as logs, blocks or the like laterally relative a desired centering line while at the same time feeding the workpieces in their longitudinal direction along a predetermined saw line towards and into the saw.

When feeding, for example, logs through a saw it is important that the logs are so positioned laterally that the highest possible yield is obtained. In most cases it is also desired that the position of crooked or curved logs is adjusted so that the curve is oriented in the vertical plane. It is normally sufficient, subsequent to ensuring that any curve present in a log is vertically oriented, if the centres of the top end and the butt end of the log coincide with the saw line, although it may also be desirable to align the log so that its centre line lies to one side of said saw line, or so that said centre line is not parallel with the saw line but that one side of the log is substantially parallel with said saw line.

When sawing logs, the saw operator is often positioned in the geometric extension of the saw line behind the log. In this way, the operator has a good view of the sawing operation and is able to position and align the log by remote control. Tests have shown, however, that despite this the saw operator is not able to align and position the log in an acceptable manner, even when he is under no pressure with regard to time. As will be understood, the result is even worse when the operator is subjected to pressures of time, caused by the high production capacities now required of such sawing operations.In recent years one has attempted to reduce the aforementioned disadvantages by aligning and positioning the log in a position separated from and located on one side of the saw line, thereby affording the operator more time to rotate and align the log so that a curve therein can be oriented in the desired manner, whereafter the log is lifted from this position to the saw line onto feed means in front of the saw.

It has been found difficult, however, to maintain the log in its adjusted and aligned position while lifting the log to said feed means and subsequently feeding the log forwards and through the saw. This also applies to maintaining the desired positioning of the centre line of the log in relation to the saw line. Since, as will be understood, it is most important that the top end of the log enters the saw in the manner desired, automatic centering means have, in recent times, been arranged before the saw and as close thereto as possible. In general, these centering means comprise an arm or a roller arranged on both sides of the saw line and arranged to press against the sides of the log with mutually the same force. If, however, one arm of the centering means strikes a knot, the top end of the log will be displaced to one side, thereby greatly reducing the yield.Even though the top end of the log may enter the saw in the manner desired, the butt end of the log may be wrongly positioned, thereby negatively influencing the yield.

The primary object of the present invention is to provide an apparatus of the kind described in the introduction, which eliminates or reduces the aforementioned disadvantage encountered with previously known apparatuses.

In accordance with the invention this is achieved with an apparatus having the features disclosed in the accompanying claim 1.

Preferred embodiments and further improvements of this apparatus have the characterizing features disclosed in the accompanying claims 2 to 17.

In an apparatus according to the invention knots on the logs will not or only to a negligible extent be able to destroy the desired centering of the logs and the centering means will move together with the logs in their feed motion towards and into the saw, whereby the desired centered and aligned position of the logs is safely maintained during this process.

In the following the invention will be described in greater detail with reference to the accompanying schematic drawings, in which Figure 1 is a plan view of a fore log carriage in a frame saw, provided with centering means according to a first embodiment of the invention; Figure 2 is an end view taken on the line l-i in Fig. 1; Figure 3 is an end view of a fore log carriage in a frame saw provided with a second embodiment of the invention; Figure 4 is a plan view partially in section of the apparatus illustrated in Fig. 3; Figure 5 is a plan view of the infeed side of a frame saw, showing means for detecting curves in the logs, for rotating the logs and transferring the same to the saw line as well as fore and rear log carriages; Figure 6 is a view taken on the line ll-ll in Fig. 5;; Figure 7 is a view taken on the line Ill-Ill in Fig. 5; Figure 8 is a plan view of the infeed side of a reducer, showing a further embodiment of centering and feeding means according to the invention.

Figure 9 is a side view of the embodiment illustrated in Fig. 8: Figure 10 is an end view taken on the line IV-IV in Fig. 9; Figure 11 is a plan view of the infeed side of a reducer, showing means for sensing a curve in a log; for rotating the log; for transferring the log to the saw line; acceleration rollers and centering devices; Figure 12 is a plan view of means according to the invention for the sawing of curved blocks; Figure 13 illustrates another embodiment of the means illustrated in Fig. 12; Figure 14 is a schematical plan view of a saw mill provided with apparatuses according to the invention, illustrating the flow of logs and blocks through the mill; Figure 15 is a plan view of a further embodiment of the invention; and Figure 16 is an end view of the embodiment in Fig. 15.

Figs. 1 and 2 illustrate a fore log carriage 1, on which the top end of a log 2 rests on a support 3 mounted on a chassi 5. The support 3 is of conventional construction, such that a log can be rolled onto the carriage from one side thereof. In the illustrated embodiment, the support 3 can be moved laterally on shafts 4 for lateral displacement of the log.

Mounted on the chassi 5 are two centering means 6 and 7. These centering means 6 and 7 can be swung outwardly and inwardly relative to the saw line 8, around bearings 9 and 10, in a manner such that they constantly and simultaneously move to the same extent in relation to the saw line 8. Each centering means comprises a plurality of flexible coil springs, spring-tensioned lines or the like bearing against the side of the log. In the illustrated embodiment, there are used lines 11 which are firmly fixed at their lower ends to respective centering means, while the upper ends of said lines are each fixed to a respective pressure spring 1 2. When a log is to be centered, the centering means are swung inwards against the log, the lines 11 acting on both sides thereof. The lines will yield somewhat in that the springs become compressed.If one of the lines 11, e.g. that referenced 1 3 in Fig. 1 and 2, contacts a knot 14 on the log, this line 1 3 will yield to a greater extent than the others. Since many lines act on the log from both sides thereof, while normally at most one of said lines will strike a knot, the centering of the log is not influenced at all hereby, or only to such a slight extent as to be insiginficant. It will also be understood that any knot present in the log will often be located between the lines or that if a line contacts a knot, the line will slide off said knot, to lie adjacent the same.

Figs. 3 and 4 illustrate a fore log carriage 15, in which centering of a log 1 6 is effected by centering means according to another embodiment of the invention. Also in this case, the centering means is conveniently mounted on a laterally movable chassi 17, and comprises a V-shaped holder 18, four centering arms 19,20 and 21,22, and housing 23 and 24 respectively. The log 1 6 is lifted or rolled onto the carriage so that it rests on the centering arms 19,20 and 21,22. As will be seen from the schematic, sectional view in Fig. 4, the inwardly facing ends of the arms 19 and 21 are chamfered and arranged to cooperate with similar chamfers and adjacent ends of a respective spring-biased locking piston 25 and 27.In the illustrated example, the side of the log against which the detecting arms 1 9 and 20 bear is smooth and straight, whereby the locking piston 25 is prevented from being moved to one side by the arm 20, which bears against said log side and is pushed a short distance into the housing 23.

Thus, the log is supported on ona side by the arm 19. Located on the other side of the illustrated log is a knot 26, which has been contacted by the arm 21, which as a result thereof has been pushed into housing 24, causing the- locking piston 27 to be moved to one side and thereby block the passage of the arm 22. Thus, the log will rest on the arms 1 9 and 22, without the presence of the knot 26 affecting its centered position. In their rest position, the centering arms are held out from the housing by respective springs 28.

Figs. 1 5 and 1 6 show schematically still another embodiment of a centering means according to the invention. This embodiment comprises two centering arms 94 and 95 which are pivoted about axes 94a and 95a, respectively, so as to be swingable to and from the centering line 96, symmetrically.

Each arm 94 and 95 carries a first yokeshaped member 97, which is pivotable about an axis 97a and which supports at its ends two additional yoke-shaped members 98 and 99, which are pivotable about axes 98a and 99a, respectively. These additional yokeshaped members 98 and 99 are at their respective ends provided with fixed abutment members 101 projecting towards and bearing against the adjacent side of the log 100 to be centered. If one of these abutment members 101 should strike a knot on the log 100, the corresponding yoke members 98 or 99 will be pivoted to a somewhat oblique position as will also the yoke member 97. As a result the log will be displaced laterally relative to the centering line 96, but this displacement will be much smaller than the actual height of the knot. With four abutment members 101 on each side of the log, the lateral displacement of the center line of the log 1 00 relative to the centering line 96 will be only one eighth of the height of the knot. By using more abutment members 101 and a correspondingly larger number of yoke members it is possible to reduce the lateral displacement of the log still more.

When using frame saws, the logs generally rest with the butt end on a rear log carriage and the top end on a fore log carriage, which carriages are provided with means for rotating the log and holding it firmly in its aligned position. Rotation of a log to ensure correct orientation of any curves therein can in certain cases be carried out during feeding of the log towards the saw.

Figs. 5, 6 and 7 illustrate how logs can be oriented and aligned and fed through a frame saw by means of an apparatus in accordance with the invention. A log 29 has been moved forward on double-cone rollers 30 and stopped with its top end abutting a stop 31.

The rear end of the log can be lifted by a rotator 32 in a manner such that it no longer rests on the rollers 30, while the top end of the log rests on a V-shaped support 33. A plurality of rotators 34 and 35 are provided, so that logs of differing lengths can be rotated. A detector 36, which is illustrated schematically as comprising photo cells and means for generating light beams, senses the diameter of the log as close to its centre as possible, or at any other location considered suitable.

To this end, a plurality of detectors 37 and 38 are provided. If the log is straight, or any curve therein lies already vertically, no measures need be taken. If, on the other hand, the log is crooked, with, for example, a curve facing to the left as illustrated at 39 in Fig. 7, the photo cells located on the left side of the log will receive less light than those on the right side, wherewith the rotator 32 is energized and rotates the log until the photo cells on both sides thereof obtain equal amounts of light, whereupon the rotator is stopped. It will be understood that this sensing of curves in the log can be effected in many differing ways, e.g. by means of mechanical arms which move from beneath and which are arranged to sense the sides of the log.It will also be understood that sensing of said curves and rotation of said log can be effected fully automatically, either in the described manner or in a manner similar thereto.

Depending upon the length of the log, the transfer arms 40 and 41 now lift the log from the aligning position, while the remaining transfer arms 42 and 43 remain in their rest position. In order to gain time, the arms 40 and 41 may be arranged to lift the log to a waiting position 44, and there wait until it is time to place the log onto the rear and fore log carriages. In this way, the aligning position is vacant for receiving and aligning the next log at an earlier time than would otherwise be the case. When the fore log carriage 45 has taken its rest position and the rear log carriage 46 has taken a position suitable for the length of the log to be received, the transfer arms lower the log onto the carriages.

In the illustrated embodiment, these are provided with centering means of the type illustrated in Figs. 3 and 4; but the centering means may also, of course, be of the kind illustrated in Figs. 1 and 2 or Figs. 1 5 and 16, respectively. As soon as the log is placed on the carriages, the log is gripped by a gripper 47 on the rear carriage 46. Both the centering device and the gripper are pivotable vertically on a shaft 48, and, although not shown, may also be arranged for lateral displacement, as is also possible with respect to the fore log carriage in accordance with the aforedescribed.

Both the rear log carriage and the fore log carriage are normally provided with wheels arranged to run on rails. In order to enable the logtransferring arms to pass, a length of a rail on one side is removed and replaced with stationary wheels 49 or rollers in the floor, on which at least one side of the rear log carriage runs. The fore log carriage is normally located outside the working range of the log-transferring arms, and can therefore be of normal construction.

When using, for example, reducing bandsaws, it may be difficult to achieve the high capacity required with reciprocatingly movable feed means. Figs. 8, 9 and 10 illustrate an embodiment of the invention for centering and feeding logs into a reducer 50. In the illustrated embodiment it has been assumed that the logs have already been oriented so that any curves therein are vertically oriented, and that the logs shall be centered before entering the reducer 50. The log 51 is moved towards the reducer 50 resting on a chain conveyor 52, although a conveying table or like element may be used instead. In this embodiment, the centering means 53 is arranged in principle as illustrated in Figs. 1 and 2, insofar as spring-loaded lines 54 apply a centering pressure against the sides of the log.In this embodiment, however, each line is attached at each end to a stirrup 55, which in turn is attached to a chain or belt conveyor 56 having substantially vertically arranged drive and turn stations. Each stirrup is separate from remaining stirrups, or at least flexibly connected thereto, to enable passage of said stirrups around the turn stations. The conveyors 56, as also the underlying conveyor 52, are driven at the same speed as the speed of the reducer device 50. The conveyors 56 together with their stirrups and centering lines are arranged for movement on shafts 57, outwardly and inwardly relative to the saw line 58, so as to center a log, by action of, for example, a linkage system 59, and in such a manner that the conveyor on one side of the log is always located at the same distance from the saw line as the conveyor on the other side of the log.

Since logs, as a rule, taper from the butt end to the top end, it may be suitable to divide the centering conveyors 56 into a plurality of short units arranged to operate independently of one another. In this way, the top end of a following log is centered by the centering means despite the fact that the butt end of the preceding log is perhaps of much larger diameter and is located just in front of said top end. In order to further improve the centering of a log which tapers markedly, the centering conveyors 56 may be arranged so that they are able to adjust conically with the narrower part nearest the reducer while being unable to adjust with the broader part nearest the reducer. As will be understood, this only appiies when the top end of the log is fed first into the reducer.

It may also be desirable to saw certain logs with the centre lines thereof offset laterally from the saw line 58. This is enabled by displacing the whole of the centering means 53 laterally. It may also be desired to saw logs with one side surface thereof lying parallel with the saw line. This is effected by locking the centering conveyor 56 on one side of the log in a fixed position, while arranging the conveyor on the other side for movement outwardly and inwardly relative to the saw line. Setting of the apparatus to accomodate logs of differing diameters is effected by laterally displacing the centering means 53. When the top end of the log enters the reducer 50, there is a risk that the position of alignment of the log will be disturbed. It is not certain that the centering means 53 will be able to prevent lurching of the end of the log sideways.

In order to hold the log in its aligned position, there are provided one or more wheels 60 or the like which are arranged to press the log firmly down against the underlying chain.

Fig. 11 illustrates logs 61 arranged on a lateral conveyor 62 waiting to be transferred one at a time to the aligning and orientating station 63. The top ends of all logs are located on a line 64. In accordance with the aforedescribed with reference to Figs. 5 and 7, the logs are sensed and rotated by sensors 65 and rotators 66 respectively, whereafter arms 67 lift said logs to the saw line 68. A plurality of pairs of driven rollers 69 engage the sides of the log 70 to prevent it from rotating out of its position, and to feed the log towards the centering means 71. In this embodiment the centering means 71 is of the kind described with reference to Figs. 8, 9 and 10, Although the transfer and starting of respective logs 70 is effected quickly, these operations take a certain time, wherefore an unwanted interval is created between the log 70 and the preceding log 72.This interval can be predetermined by selection of the difference in speed between the roller 69 and the centering means 71, the start time and the acceleration distance. As will be understood, other devices than rollers 69 can be arranged for maintaining the position of the logs and feeding the same, without departing from the scope of the claims.

The centering means described with reference to Figs. 8, 9 and 10 are also suitable for centering and feeding blocks when using, for example, frame re-saws, wherewith in the case of a curved block the curve is automatically followed. Fig. 1 2 illustrates how a precentering means 73, here illustrated schematically with arrows, center the forward part of a block 74 approximately on the saw line 75. If the block is curved, its rear part will be located to one side of the saw line. When the precentering means 73 release their grip on the block, the block is fed towards the saw 77 by means of rollers 76. Provided the centering means 78 has a suitable length, it will apply pressure on the sides of the block so as to force the saw to follow the curve in the block.

Fig. 1 3 illustrates an embodiment similar to that illustrated in Fig. 12, with the difference that the centering means 78 has a different form. Instead of centering conveyors having stirrups and resilient lines acting on the block, the illustrated centering means comprises four or more pairs of wheels or drums on which the stirrups and lines are mounted and arranged to act on the sides of the block. As will be understood, this embodiment can also be used for centering the logs, although they are more sensitive to the presence of knots etc. on the surfaces of the log.

When aligning logs, the most time consuming operation is perhaps that in assessing the presence of any curves in the logs and rotating the same. Hitherto, all logs have been allowed to pass an operator whose function is to visually assess each separate log and to rotate all said logs, and also to ensure that said logs are correctly centered. It is impossible for an operator to fulfill all of these tasks satisfactorily when a high production capacity is required. This problem is solved by means of the present invention, since both the detection of curves, rotation and centering of the logs can be effected automatically with a high degree of accuracy. Despite this, it is important that the detection of curves and rotation of logs is not carried out so quickly as to jeopardize the desired result. Since experience shows that normally only 20-40 % of the logs are so crooked that they need to be rotated, it is suitable to sort said logs in the manner illustrated schematically in Fig. 14.

All the logs are arranged to pass a sensor 79 of known kind. The sensor examines each log and causes all regular logs which can be sawn without taking additional measures, to be transported in the direction of the arrow 80. Thus, these logs are so straight as to obviate the need of rotation, and hence they can be lifted directly, in the aforedescribed manner, over to the saw line 81, caused to pass through a centering device 82 in accordance with the above and fed through the reducer and band saw 83. The blocks from the saw 83 are turned automatically through 90 in a known manner and are fed in the direction of arrow 84 through the aforedescribed centering means 85 to a reducer and band saw 86.

Those logs which the sensor 79 considers to be so crooked that they must be rotated, are caused to be fed in the direction of arrow 87 to an aforedescribed positioning station 88, where they are again sensed, rotated and then transferred to the saw line 81 between the normal logs arriving from the other side.

These crooked logs also pass through the centering means 82 and the saw 83, but the resulting blocks are transferred in the direction of arrow 89 to a centering means 90 for curved blocks, said centering means 90 guiding said blocks into the saw 91 in the aforedescribed manner.

Even in the case of timber which has been sorted with respect to diameter it may occur that the sensor 79 detects logs which, for example, as a result of deviating quality should be sawn with a different batch than the normal one for logs of the diameter class concerned. These logs are suitably also transferred in the direction of arrow 87, but when they are to be transferred to the saw line 81, the preceding log is permitted to have moved so far ahead that sufficient interval is obtained between the logs to permit adjustment of the saws 83 and 86.

As a reserve possibility, logs arriving from the sensor 79 may also be moved straight on along the dotted line 92, wherewith any necessary rotation of the logs can be effected in a manner known per se by means of the obliquely adjustable rollers 93.

Claims (17)

1. An apparatus on the infeed side of a saw or the like for centering and aligning elongate workpieces in the form of logs, blocks or the like laterally relative to a desired centering line while at the same time feeding the workpieces in their longitudinal direction along a predetermined saw line towards and into the saw, said apparatus comprising at least two centering means (e.g. 6,7) located on a respective side of the centering line (8) and arranged to exert on each side of an intermediate work piece (2) a centering force directed towards said centering line in a manner such that the centre axis of said workpiece (2) is maintained substantially coincidental with said centering line, characterized in that said centering means (6, 7) are arranged to participate in the feed motion of the workpiece along the saw line without any relative movement between workpiece and centering means as seen in the longitudinal direction of the workpiece, and that each of said centering means (6, 7) comprises two or more centering elements (e.g. 11) bearing against the workpiece and mutually spaced from each other in the direction of said centering line, each of said centering elements being substantially individually displaceable laterally relative to said centering line in a manner such as to yield when contacting a knot or some other locally outwardly projecting part of the workpiece, while the substantial part of the requisite centering force is exerted by the remaining centering elements of the centering means in question.

2. An apparatus according to claim 1, characterized in that each centering means comprises two abutments members (19, 20) which are capable of being pressed in to a housing (23) and which form said centering elements, and locking means (25) co-operative with said two abutment members and arranged, when either of said abutment members is pressed into its respective housing, to lock the other abutment member in its outwardly projecting position.

3. An apparatus according to claim 1, characterized in that each centering means comprises at least four abutment members (101) bearing against the workpiece (100) mutually spaced from each other in the direction of the centering line and forming said centering elements, said abutment members being mounted in pairs on the ends of two yoke members (98, 99), which are pivoted in the ends of a third yoke member (97) about mutually parallel axes perpendicular to the direction of the centering line (96), said third yoke member (97) being also pivoted about an axis parallel to said first mentioned axes.

4. An apparatus according to claim 1, characterized in that the centering elements of a centering means (e.g. 6) comprises a plurality of elongate, substantially rod-shaped elements (11) arranged substantially parallel with each other in spaced relationship along the direction of the centering line and extending substantially perpendicularly thereto, each of said rod-shaped elements being resiliently yieldable substantially pependicularly to its longitudinal direction and the direction of the centering line.

5. An apparatus according to claim 4, characterized in that said rod-shaped elements comprise coil springs.

6. An apparatus according to claim 4, characterized in that said rod-shaped elements comprises spring-loaded lines or the like (11).

7. An apparatus according to anyone of claims 4 to 6, characterized in that the rodshaped centering elements (55) associated with a centering means (54) are mounted on an endless conveyor element (56) in the form of a chain or belt conveyor or the like, which runs in a substantially horizontal plane in a direction substantially parallel with the centering line and in synchronism with the feed movement of the workpiece.

8. An apparatus according to claim 7, characterized in that said endless conveyor element (56) is driven in a manner such that the centering means assist in feeding the workpiece towards and into the saw.

9. An apparatus according to claim 7 or claim 8, characterized in that the centering means are obliquely adjustable relative to the centering line about a respective substantially vertical pivot axis, so that they can adapt to workpiece whose diameters vary along the length thereof.

10. An apparatus according to any one of claims 4 to 6, characterized in that the rodshaped centering elements associated with a centering means are mounted around the periphery of a drum-like carrier, which is rotatable and optionally drivable about a substantially vertically extending axis.

11. An apparatus according to any one of claims 1 to 10, characterized in that it includes a plurality of mutually independently operating pairs of co-operating centering means arranged subsequentially along the centering line.

1 2. An apparatus according to any one of claims 1 to 11, characterized in that the two centering means of a pair of centering means arranged opposite one another on a respective side of the centering line (e.g. centering means 6, 7) are arranged for movement in a direction towards and away from each other symmetrically relative to said centering line (8).

1 3. An apparatus according to any one of claims 1 to 12, characterized in that said pair or each pair of cooperating centering means (e.g. 6,7) are mounted on a common support chassis (5) which is horizontally displaceable substantially perpendicularly to the geometric extension of the centering line, so as to adjust the position of the centering line laterally relative to the saw line.

14. An apparatus according to any one of claims 1 to 6, characterized in that each pair of co-operating centering means (e.g. 6, 7) are mounted on a carriage (1) arranged to run on wheels on a stationary surface and/or on stationarily mounted wheels in the geometric extension of the centering line, in order to participate in the movement of the centered workpiece up to and in to the saw.

1 5. An apparatus according to claim 14, characterized in that it includes two pairs of co-operating centering means each mounted on a respective carriage (45,46) in a manner such as to enable said centering means to act on the forward and rearward end, respectively, of a workpiece.

1 6. An apparatus according to claim 15, characterized in that the pair of centering means arranged on the rear carriage (46) are vertically movable.

17. An apparatus according to any one of claims 1 to 16, characterized in that the centering means is also arranged to support the workpiece.

1 8. Centering apparatus for elongate workpieces substantially as described herein with reference to the accompanying drawings.

1 9. A sawing installation including apparatus in accordance with any one of the preceding claims.