SE447303B - PROCEDURE AND PLANT FOR HEATING THE WOODWORK, WHICH WILL BE MADE MACHINERY - Google Patents

Description

447 303 I _ as this is shifted through the network.

In the initial sawing operation carried out on timber logs in a sawmill, two edge boards are usually sawn off, one on each side of the log, so that the piece of wood removed from the edge saw - now called a block - is delimited by two parallel flat sides, which form cuts with the remaining arched raw surfaces and from which one has to start when the block is subsequently to be broken down. How the saw timber is handled in the edging saw and in which positions the plan sides are cut is therefore of great importance for the timber exchange.

Therefore, in many sawmills, methods and devices have been introduced with the aim of orienting each individual log in relation to the edge saw blades or saw blades at the moment of loading, so that the saw cuts make these cones as favorable as possible. In doing so, consideration may be given partly to the log's geometric shape and dimensions, and partly to the disintegration alternative (the posting) that the sawmill is currently working with and which determines how saw blades or blades are to be mutually set on edge saws and split saws.

A rule of thumb for logging is to look for the orientation that results. in a symmetrical position of the plane sides in relation to the center plane of the log, whereby with a non-ideal cylindrical shape of the log the plane sides become congruent. The fact that the plan sides have the same width and have a similar configuration is essential for minimizing the length of the block when splitting the block: the length of spills and unedged side boards. Getting the cuts for the flat sides to go symmetrically along the log also usually means that the volume of the material, which is separated in the form of the two edge boards and which is largely wasted, then becomes the smallest possible. Even if one utilizes the very best methods and aids available for logging, it is in practice impossible to avoid that the saw cuts that the edge saws provide will be slightly laterally offset or skewed in relation to the intended most advantageous position in the log.

Such deviations can occur e.g. due to a damage or mechanical wear in the sawing machine, an incorrect setting of saw blades or saw blades, an electrical fault in a system that controls the inlay or another systematic fault. Another cause can be nails or the like, which causes a saw blade to become blurred and can result in a skew, ie that a log does not maintain the position in which it is inserted but has an increasing lateral displacement. 447 303 Another error in edge sawing may be that the block height, ie the distance between the plane sides, deviates from the dimension that must be contained in order for the decomposition to be correct.

If errors of the kind mentioned occur during automatic loading and edging of a timer part, a significant loss may occur, unless the operator who monitors loading and edging detects the error when inspecting the blocks and stops the machine - a measure which he may otherwise be reluctant to take. with regard to the disturbance in production that arises during a downtime. Therefore, an error of the above-mentioned type which occurs during the work in an edge saw probably results in a long series of logs being sawn with asymmetrically or otherwise unfavorably oriented saw cuts and lower yields from the blocks as a result, before the error can be corrected. Although the deviation from the intended non-profit positions for the plan sides appears insignificant, measured in millimeters on the individual blocks, large financial losses can occur. The object of the present invention, which is based on the realization that it is a matter of detecting and correcting an erroneous behavior as early as possible in a plant where edge sawing of timber to blocks is carried out, has for its object to provide a method and a device for determining the geometry of pieces of wood which in a sawmill machine appear in the form of blocks and that by means of geometrical data produced for the blocks monitor that the insertion of the pieces of wood into the machine and the subsequent processing takes place correctly.

A special object of the invention is to check, on the basis of obtained measurement data for a block which just emerges or has emerged from an edge saw, whether both plane sides of the block deviate impermissibly from predetermined positions and, if so, to provide an indication which the sawmill staff shows that the ongoing machining of the edge saw should be interrupted.

Another aspect of the invention is based on the fact that in order to optimize the disintegration of pieces of wood, it is essential to know the configuration of the two planar sides of wood blocks. A further object of the invention is therefore to produce data which show the mutual shape and position of the plan pages by a measurement of pieces of wood processed 447 zos into blocks in a primary operation in a disintegration program and by using 2 in the subsequent disintegration of the block can enable an increased yield in the form of finished wood. The above-mentioned end needle and object is achieved according to the present invention by the method and the plant obtaining the features stated in the claims. The invention will now be explained in more detail below with reference to the accompanying drawing, in which Fig. 1 is a schematic diagram of a plant according to the invention. Fig. 2-3 is a side view resp. end view of parts of the plant æh a block transported thereby at an edge. Figs. 4-5 show in an analogous manner corresponding parts in an embodiment in which blocks are transported lying down. I Den i fi_g. The plant illustrated in 1 is assumed to be included as a station in a sawmill in which timber is sawn into boards and other wood products. Eh primary operation in this machining is the loading of the timber into an edge saw, in which the logs one by one pass two parallel saw blades or chopping discs which cut off outer parts of the logs. The pieces of wood then take the form of blocks which, depending on the starting material, can have strongly varying coarseness, but which are largely uniform in cross-section. In the drawing, a block denotes a block cut from a rough log, while g can be assumed to represent the smallest block cross-section present in the plant. Regardless of the coarseness, the cross sections of the blocks have two curved raw surfaces - 1 and 2 that face in opposite directions and are rough and irregular, especially if the saw blade is delivered unbarked. 3 and 4 denote the cuts obtained during edge sawing, hereinafter referred to as the planar sides. With correctly executed edge sawing, the plan sides are mutually parallel and approximately the same width. The intersection lines 5-8 between raw surfaces and planar sides run more or less irregularly at the same time as they usually diverge slightly, seen in the longitudinal direction of each planar side, as as is well known tisrrn-er-f logs are not completely straight and cylindrical but usually have some curvature or other deviation from the generally somewhat conical basic form.

Determining the geunetric shape of the cuts 5-8 and thus the shape 447 303 of the two planar sides is an important step in the realization of the invention.

The sawmill station which the plant according to the invention is intended to constitute may be located between the edge saw and a split saw (neither shown in the drawing) and in such cases the blocks å, g are fed longitudinally by a conveyor which in Figs. 1-3 is generally indicated 9 and on which the blocks emerges one by one. Alternatively, the station can be located within the active area of the edge saw, whereby the pieces of wood are fed by the saw machine's own drive means. In cases where edge boards are separated from the piece of wood, in this alternative such boards can still be hairy attached to the piece of wood on either side of the block, as this passes the station, without this hindering the treatment therein. In such a case, "block" shall mean the actual block part å, b together with the two edge boards existing on either side thereof.

In the drawing, 10 is a reference plane, which is parallel to the plane sides 3, 4 of the blocks when these are fed longitudinally on the conveyor 9 and whose direction coincides with the conveyor. In a position along this is a measuring zone 11 which is generally a narrow area, at an angle to the direction of transport and the reference plane 10, through which the blocks pass and which contains two measuring planes 12, 13 so directed towards their intersections with the reference plane 10 and thus with the sides 3, .4 becoming perpendicular to the direction of transport.

In Fig. 1, both measuring planes coincide with the drawing plane.

For netting of each block produced by the measuring zone, the plant has a photoelectrically operating network system comprising two cameras 14 and 15, each of which operates in one of the network planes 12, 13 and is directed towards the respective plan side of the block. The cameras, which may be of the well-known type which have an array of photodiodes and whose construction and mode of operation therefore do not need to be described in more detail, each provide in a fast, repeated measurement sequence an electronically readable linear image of the present camera. "sees" within the area it scans, which is illustrated in Fig. 2 by 16. With mutual close distances, the measuring system thus depicts transverse segments of the block as it is fed through the measuring zone. The measurement signals from the cameras are output to an electronics unit 17 where a processing of the measurement data representing the mentioned segments takes place.

A system of radiation sources is arranged with the measuring system, which is arranged to irradiate the part of the block in \ i 1 in a manner which is favorable for the measurement. 1 l. According to a primary feature of the invention, the plant comprises two opposite radiation sources 18 and 19 which are arranged on opposite sides of the conveyor 9 and arranged so that their beams 20 and 21 falls along the reference plane 10, i.e. substantially parallel to the plane sides 3, 4 of the block. In this case, the two raw surfaces 1, 2 on the block __ in the measuring zone are strongly irradiated and emit reflected light which is absorbed by the cameras 14, 15. The two plane sides, on the other hand, become unirradiated or only slightly irradiated. of the radiation sources, so that the planar sides frame to reflect mainly only the dim light from the surroundings.

The result of this is that the two raw surfaces frame to appear in each camera in contrast to the planar side facing the camera. This in turn leads to the fact that in the scanned area 16 there are two positions where the received radiation shows a sharp decrease, which can be easily indicated by the electronics unit resp. increase. Nbtsvarax fi e points of course occur in the scanned area of the other camera, however, in positions that .here may be different depending on the irregular shape of the edge-sawn tin bucket, and possibly. error in edge sawing. The four näm itions now mentioned represent points on the intersection lines 5-8 between raw surfaces and planar sides.

According to the features of the invention, the plant also includes means for determining the position of the two plane sides 3, 4 in relation to the cameras 14, 15.

In the exemplary embodiments shown, said means consist of laser separators 22, 23, one for each camera and arranged so that their beam directions fall from the outside obliquely towards the measuring zone and in those to resp. camera belonging to the measurement plan 12, 13.

The laser transmitters emit beams of light 24 with a narrow cross-section and each therefore projects a small spot of light 25 when the radiation, as can be seen most clearly from Fig. 1, hits a block known in the measuring zone. The light spots fall on the substantially unirradiated plane sides 3, 4 and can therefore be easily detected by the cameras and electronics of the measuring system axis.

It will be appreciated that with the large block cross-section the light spots .25B in Fig. 1 in frame 1 fall relatively high up on the planar sides, while with decreasing the thickness of the block the spots strike the block in a lower position in the measuring zone. By suitable alignment of the laser transmitters, however, it can be achieved that the lobes, even at the smallest block cross-section g, fall on the machined surfaces of the block facing the cameras, now in points 25b. It follows that .ag-w 447 303 ......... -. \ .....- «. U.» - that the position of the light spots within the area 16 'scanned by each camera tends to be in a linear relation to the position of the surface, ie the angular distance between the reference plane 10 and the respective plane side 3 or 4. The positions therefore constitute an accurate measure of the distance between the person in the plane side and the camera focal plane F (see Figs. 3 and 5) where the photodiode array is located.

Thus, for each measurement sequence: the network system has access to a unique combination of six positions in the camera arrays for the block segment just searched, namely the four above-mentioned positions corresponding to the detected points on sections 5-8, and the two corresponding positions against the detected laser light spots 25. By a conventional calculation method, which is implemented in the electronics unit 17, it thus becomes possible to determine the coordinates in the measuring plane 12, 13 for the four intersection points. A network accuracy of 1/10 nm is possible in this case. The electronic unit also enters data indicating how the block is located in the measurement zone 11 at the same moment as a measurement sequence is performed. This data can be obtained on the basis of a pulse signal emitted from an encoder 26 connected to the conveyor 9, and a photocell signal which is generated when the front end of the block intersects the measuring plane 12, 13. When the block as a whole has passed the measuring zone and thus become in its measured as a whole, the measuring system thus has all the information to make a complete and accurate determination of the geometry of the two flat sides 3 and 4 of the timber piece in a three-axis coordinate system is thus also determined, ie. the measure of the block height can easily be taken at different points along the block and such measurements can be displayed block by block on a presentation means 27 connected to the microcomputer, or alternatively registered centrally in a higher-level computer 28.

In accordance with the primary object of the invention to monitor how well the blocks obtained during the edge sawing conform to the applicable requirements, a control calculation can be made on the basis of the geometric determination made for the planar sides which shows the position in which they were cut and whether can be accepted or not. The control calculation can be performed in many different ways and suitably follows an algorithm which can also be implemented in the electronics unit. 447 303 f - e A preferred way is to determine, on the basis of values of the average width of the planar sides, the oblique insert that occurred during the edge sawing, ie the possible asymmetry that can be ascertained between a block's planar sides and the log's original geometric center plane. In this case, values of the average width can first be produced; calculated on different predetermined sections of the block length, after which, with the help of experiential values of the curvature of the log cross sections and the generated width values, the asymmetry that occurs, section by section, is calculated. The values obtained for the oblique installation may then be related to current requirements, which can be expressed in the form of limit values. According to an alternative control procedure, the ratio between the average widths of the two plan sides is calculated, after which the ratio that can be said to be a measure of the oblique placement, block by block, is compared with a limit value.

With the normally occurring quality of the sawn timber, it must be tolerated that the average width of the planar sides and thus the calculated values of the inclined insert vary and that deviations occur from the non-profit block forks. The said limit values are therefore chosen in the individual case so that they distinguish the deviations in the block shape which affect the yield in the subsequent decomposition. Statistical processing of the skewed input values can further show whether the machine equipment is affected by systematic faults and whether its quality and status change.

Another way of using the coordinates obtained during the measurement of the blocks is to check the height of the block, ie the distance between the plane sides, which dimension is fundamental for the disintegration of the block; In the system according to the invention, one can, suitably by means of a keypad 29 at the presentation means, control the automatic monitoring of the system by reading into a memory in the electronics unit the tolerance values which are to apply to the various posting alternatives which may occur and of which the above limit value is one, while another tolerance value may show permissible dimensional deviations in the block height. With these read-in, tolerance values as a basis, the electronics unit calculates as the blocks are transported through the network zone data showing how the accuracy requirements applicable to edge edging are met. This data can be followed by an operator on the presentation means 27. 447 303 .I _ ..... A ... l ....._ ..: ..._._ J In the event that the check shows that unauthorized deviations begin occur, the operator is thus warned and can quickly intervene by stopping the work in the edge saw. An even greater certainty for the operator to pay attention to the error and thereby prevent an unnecessary number of logs from being incorrectly loaded or processed in the machine is gained by letting the electronics unit 17 emit a warning signal when a valid color value is exceeded according to a special feature of the invention. the warning signal is transmitted via a line 30 to a unit 31 supplied from the mains, which controls the power supply to the plant's radiation sources and laser projectors and which also triggers an optical or acoustic alarm device 32 when the warning signal occurs. It may be pointed out here that this in alarm function should be triggered only when the electronic system indicates that the impermissible deviation was not temporary but occurs similarly for a sequence of blocks. The fact that occasional incorrect blocks appear can have other causes than machine errors or misalignment and can e.g. due to an abnormal geometric shape of a log.

In drawing figures 2-5, the same designations as in Fig. 1 are used for parts which are the same and described above. When the installation is carried out according to Figs. 2-3, the conveyor 9 may comprise a carrier chain 33 which is located in the reference plane 10 and is narrow in relation to the smallest block cross-section b, so that it does not prevent the outer parts of the lower surface 2 from being irradiated and the cuts 7 and 8 become detectable. The conveyor includes a plurality of clamping rollers 34 which are held in contact with the upper surface 1 of the blocks and have a concave profile as Fig. 3, whereby the clamping rollers guide the blocks out of the measurement so that the flat sides 3, 4 become at least substantially vertical.

It is understood that a sloping plan side means that the coordinate determination of its intersections 5, 7 or 6, 8 is erroneous and that these should be compensated before the measurement result is used. In the embodiment of the invention according to Figs. 2-3, therefore, two pairs of beams 35 'and 35 "are projected from the laser units 22, 23 with the beams in each pair substantially parallel and mutually laterally offset in the direction of the network plane 12, 13, of the laser units it is ensured that on each plane side 3, 4, regardless of the thickness of the block, two light spots 36 'and 36 "are generated, one directly above the other. In analogy to what has been said above regarding the plant in Fig. 1 and the measurement procedure therein, the four positions 447 303 f _ 10 in the array cameras which: correspond to the light spots to be registered by the network system and because this has exact information about the inclination and the mutual distance for the laser lobes in each pair, regardless of the distance between the camera and the plane side, it becomes possible to calculate by a comparative analysis of the distance values corresponding to the four positions whether, and if so how much, the plane sides 3,4 are inclined relative to the reference plane 10. then the block passes the measurement zone. The training screens 1a, 19 can: As in the variant in Figs. 4-5, consist of lamps arranged in pairs, each with its own reflector, in order to obtain good parallelism in the irradiation.

In the embodiment according to Figs. 1-S, the transport takes place by means of belts or similar wide drive means which feed the blocks with these lying on one plane side, whereby the reference plane 10 thus becomes horizontal. To enable defrosting from below, the conveyor is made in two units 37 and 38 which are mutually separated in the direction of rotation, so that one camera 39 and the laser projector 41 operating in its measuring plane 40 can be arranged below the conveyor while corresponding components for measuring the blocks from above can be arranged in a vertical: network plane 42. This should cut the reference plane 10 at the same place as this is cut by the lower measuring plane 40. However, it is acceptable that as Fig. 4 shows arrange the latter plane inclined, whereby by means of a screen 43 one can protect the two obliquely upwardly directed grain components 39 and 41 from dust and similar contamination. In the same way, a protective screen 44 should be fitted in the embodiment according to Figs. 2-3 to ensure the blocks transported on the high edge an effective irradiation from below.

It will be appreciated from the foregoing that the method and plant according to the invention opens up an opportunity for effective monitoring of the work in an edge saw and in the event of an unacceptable error in the form of laying down or lateral displacement of the saw cuts' enabling a rapid entry and remediation of the error. uH-.uu-.f fl- ~ 447 30.3 The invention can also be used for the disintegration of the blocks occurring after the edge sawing. Once an electrically readable determination of the block geometry has been obtained in the plant in the manner described above, a further analysis can be performed by continued data processing in the parent computer which can be used as a basis for the control of the splitting saw. In this case, e.g. is calculated to what extent the plane sides are mutually overlapping or offset in the plane, or if the plane sides have such a curvature that justifies that so-called hook sawing is performed. The coordinate determination of the blocks according to the present invention can thus also in this way contribute to a better utilization of the timber.

Claims (1)

447 = 3-03 'in Claims claim Method for machining elongate pieces of wood, resulting in blocks which have a cross section (Q, EQ comprising two curved, oppositely facing raw surfaces (1,2) and two machined planar sides (3,4), which are substantially parallel and with the raw surfaces form intersections (5-8) which run irregularly along the block, in which process blocks one and one are displaced longitudinally along a reference plane (10) passing through the block and is substantially parallel to the plane sides, the block passing through a measuring zone (11) extending transversely relative to the reference plane and in which cross-sectional dimensions of the block can, as it is displaced through the measuring zone, be repeatedly measured by a photoelectric measuring system scanning the measuring zone , and wherein the block in the measuring zone (11) is irradiated by means of two beams (20, 21) falling along the reference plane (10), each of which is projected towards one of the raw surfaces (1,2), so that t the two raw surfaces are strongly irradiated while the two plane sides (3, ä) receive no or only weak radiation towards the plane sides, characterized by the fact that radiation originating from the beams and reflected from the raw surfaces (1,2) is received by two opposite cameras (14, 15; 39,42) located on opposite sides of the reference plane (10), which belong to the measuring system, so that each camera detects the intersections (5,7; 6,8) between the one by means of the received radiation. of the flat sides (3,4) of the block and the two raw surfaces (1,2), that the two distances between resp. camera and the part of the plane side scanned by the camera is determined, and that by means of data for the detected intersections and the mentioned distances the coordinates of the two plane sides (3, ä) are determined. Method according to claim 1, characterized in that the two cameras (14,15; 39,42) scan linearly and within measuring planes (12,13; 40,44) which in opposite places intersect the plane sides (3 , 4) perpendicular or substantially perpendicular to the longitudinal direction of the block. t, ..........._ -._'...__..._...._. A method according to claim 1 or 2, characterized in that, based on the coordinates of the plane sides (3,4), a check of the relative size of the plane sides is made in a calculation unit (17), preferably by comparing their average width, and that when the control calculation shows that the planar sides deviate from each other of the measured block or a sequence of blocks, a signal is issued for triggering alarms, so that further processing into blocks with such deviations can be prevented. Method according to Claim 1 or 2, characterized in that, based on the coordinates, data showing the most advantageous position and shape of the block decomposing in a computer (28) are generated, after which signals based on such data are generated as may control a split saw in which these saw cuts are made. Method according to claim 2, characterized in that narrow beam lobes (24; 3S), preferably laser lobes, which extend along the measuring plane (12,13; 40,44) at an oblique angle to the reference plane (10), are projected towards the plane sides (3). , 4) and that the said distances are determined by the cameras (14,15; 39,42) receiving radiation reflected from the spots (25; 36) on the planar sides (3,4) where the beam lobes (24; 35) are incident, and generates position signals for the spots. Method according to Claim 5, characterized in that two substantially parallel beam beams (35 ', 35 ") are projected towards each plane side (3,4) and mutually laterally displaced laterally offset beams (35', 35"), so that two spots are generated on each plane side. 36 ', 36 "), and that the distance of each spot to the camera (1 &, 1S) -, is determined so that data can thereby be obtained showing if and how much the plane sides are inclined relative to the reference plane.., -. ..-, -_. -....-_.-. c ...-.-. ~ ..._..._ = _ V.-._.._. ..._- 14 447 303 7. Plant at machine machining of elongate pieces of wood in which blocks appear, which have a cross-section Qâ, b) comprising two curved, oppositely facing raw surfaces (1,2) and two machined flat sides (3,4), which are in the main parallel and with the planes form cuts (5-8) which run irregularly along the block, which plant comprises means (9) for displacing blocks one by one along a reference plane (10) which passes through the block and is substantially parallel to the planar sides (3,4), a measuring zone (11) extending transversely relative to the reference plane so that the block at the displacement passes therethrough and at which there is a photoelectrically acting measuring system arranged to scan the measuring zone and with which cross-sectional dimensions of the block can be repeated measured as it is displaced through the measuring zone, and two opposite radiation sources (18,19), which are arranged to irradiate a surface (1,2) located in a block in the measuring zone so that these are strongly irradiated while the two planar sides of the block (3,4 ) become unirradiated or only slightly irradiated and the raw surfaces thereby appear in contrast to the plane side, characterized in that the measuring system comprises two opposite cameras, located on either side of the reference plane (14,1S; 39,42), which are arranged to be and one detects by means of the received radiation the intersections (5,7; 6,8) between one of the flat sides (3,4) of the block and the two raw surfaces (1,2), and a device (22,23; 41,43) me d whose help the two distances between resp. camera and the part of the plane side scanned by the camera can be determined, and the plant has calculation means (17) for determining the coordinates of the two plane sides (3,4) from data obtained from the cameras and refers to said cuts and distances. Plant according to claim 7, characterized in that the cameras (14,15) have a linear array of photodetectors with which they scan flat measuring areas, as in 10. 11. 447 BUS opposite places of a block in the measuring zone cut its planar sides (3,4) perpendicular or substantially perpendicular to the direction of displacement and thus to the longitudinal direction of the block. Plant according to claim 7 or 8, characterized in that the calculation means (17) is arranged to perform a control calculation with respect to their relative size by means of the coordinates of the plan pages (3,4), preferably by comparing the average width of the plan pages. and forming a control signal indicating if the plane sides deviate from each other of the measured block or a sequence of blocks, and that the calculation means (17) is operatively connected to the presentation and / or alarm means (27, 32) which receives the control signal, so that further processing into blocks with such deviations can be prevented. Plant according to claim 7 or 8, characterized in that the calculation means (17) is connected to a superior computer (28), which is arranged to calculate data showing the most advantageous position based on the coordinates of the plan pages (3,4) and shape of the block disintegrating saw cuts and generating control signals based on such data which are connected to a splitting saw, for performing these saw cuts. Plant according to claim 8, characterized in that the device by means of which the distance determination takes place comprises transmitters for emitting narrow beams (20; 35), preferably laser transmitters (22, 23; & 1.43), which beams extend along the measuring plane of each camera. (12,1}; 40, üh) at an oblique angle to the reference plane (10) and are so directed that they are incident on the plane sides (3,4) and the spots (2S; 36) on these where the ray lobes (24; 35) incidence can be positioned by detection in the cameras (14,15; 39,42). Ié 447 303 12. Plant according to claim 11, characterized in that on each side of the reference plane (10) there are two transmitters which are directed substantially parallel and are laterally displaced in the measuring plane (12,13), so that on each plane side (3,4) two light spots (36 ', 36 ") are generated, and that the camera (14,15) is arranged for determining the position of both these spots, whereby data on possible inclination of the plane sides can be obtained. .. .4 ...._. A.- _. M1 ... »v- n- - -nm