Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27B—SAWS FOR WOOD OR SIMILAR MATERIAL; COMPONENTS OR ACCESSORIES THEREFOR
  • B27B1/00—Methods for subdividing trunks or logs essentially involving sawing
  • B27B1/007—Methods for subdividing trunks or logs essentially involving sawing taking into account geometric properties of the trunks or logs to be sawn, e.g. curvature
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27B—SAWS FOR WOOD OR SIMILAR MATERIAL; COMPONENTS OR ACCESSORIES THEREFOR
  • B27B31/00—Arrangements for conveying, loading, turning, adjusting, or discharging the log or timber, specially designed for saw mills or sawing machines
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27B—SAWS FOR WOOD OR SIMILAR MATERIAL; COMPONENTS OR ACCESSORIES THEREFOR
  • B27B31/00—Arrangements for conveying, loading, turning, adjusting, or discharging the log or timber, specially designed for saw mills or sawing machines
  • B27B31/04—Turning equipment

Definitions

• the present invention concerns a sawing method according to the preamble of claim 1 for compensating the drying spirality of sawn timber.
• the invention also concerns a sawing apparatus according to claim 8 for compensating the drying spirality of sawn timber.
• the sawing blank is sawn into desired sawn timber with a certain setting.
• the sawn timber is dried to the moisture content depending on the usage (0...24%), it is often twisted propellerlike around its longitudinal axis.
• the propeller-like distortion of the sawn timber during drying is caused by many different factors, generally called spiral grain of the wood.
• the best description of the drying spirality is given by publication NR. 97 of VTT (Technical Research Center of Finland) of 1997; Decreasing the distortion of sawn timber by means of drying.
• Tree trunk in this connection refers to pruned small sized wood, trunk or sawn logs (timber).
• Trees almost always grow as twisted. Spirality is not constant, but it can be spiral even in different directions with the same wood species and within an individual tree.
• the cells of the heartwood usually are spiral to the left and the cells of the sapwood to the right, whereby it is difficult to foretell the direction and de- gree of spirality of a certain tree trunk.
• the trunk then is chipped into a balk and the balk is sawn with a certain setting into sawn timber to be dried to a certain moisture content, the amount of drying spirality of the final dried sawn timber is not easily predictable. The biggest problem is caused when the sawn timber or the final products made of it are twisted already before delivery to the site.
• these factors having influence on the drying spirality are differences of the grain angles of different flats of the sawn timber and the amount of the juvenile wood in the sawn timber and the point, when the grain angle has reversed.
• the growth rate and changes in the wind conditions are affected, among other things, the growth rate and changes in the wind conditions.
• Juvenile wood is the part of the heart of wood, where the grains are twisted prominently and the cells shrink more in the longitudinal direction than those of normal wood during drying.
• Blade setting in this application refers to the kind of sawn timber to be sawn up from a saw log received from a certain tree trunk/log. Depending on the diameter of the saw log, usually two or more battens or blanks or one balk and a variable number of boards are received.
• the (blade) setting used for the log depends on the sawing method and on the diameter of the log to be sawn. With respect to the settings, reference is made to the literature of the art.
• the object of the present invention is to solve the problems occurring in the technology of prior art referred to above.
• the main target of the invention is to provide a method and apparatus, by which it is possible to decrease spirality of the sawn timber without increasing the drying time or without leaving stresses in the wood, that could break up later.
• the method in accordance with the invention is based on the experience, that the influence of the grain angles of the saw logs to be sawn, on the drying spirality of the sawn timber can be forecast with certain accuracy. It is possible to measure, calculate and/or evaluate the drying spirality, and based on this grain angle values and other values measured and/or evaluated from the sawn timber it can be forecasted with adequate reliability. In a forecast, it is in most cases taken into account, how the grain angles discovered in the earlier sawn tree trunks have correlated with the drying spirality discovered in the dried sawn timber received from the same.
• the method in accordance with the present invention is based thereon, that the angle between the line segment defined by the saw blades and the line segment defined by the mathematical center point of the trunk in the cross-sectional profile of the trunk, is subjected to a controlled deviation, which is the contrary to the estimated, measured or forecasted drying spirality of the trunk/sawing blank/sawn timber.
• estimating the drying spirality at least the following is preferably taken into account: grain angles, (saw blade) setting, drying degree of the sawn timber and the growth speed of the tree, which can be measured by means of automatic meters.
• generally also summer growth percentage diameter of the trunk and the temperature of the trunk to be processed, quality, form, amount of knots of the trunk and the wood species are taken into consideration.
• Sawing plane refers here to the plane defined by the longitudinal axis of the blades.
• the trunk is sawn in a certain sawing phase, like when sawing square timber, with two parallel blades, which means that there are also two sawing planes.
• the certain reference line segment defined by the center of the cross-sectional profile of the trunk is mostly a fixed vertical or horizontal line, in case the trunk is moved forward on the sawing line without rolling it. In case the trunk is rolled, the reference line segment defined by the center of the trunk is selected to be any line segment passing via the mathematical center of the trunk.
• the drying spirality of the sawing blank and/or sawn timber is estimated or/and calculated. It is also possible to measure and/or estimate drying spiralities of the sawn timber in other ways.
• the trunk is sawn with a counter spirality that compensates the drying spirality, whereby the sawn surface turns around the trunk so that the angle between the line segment defined by the saw blades and the comparative line segment defined by the mathematical center of the cross-sectional profile of the trunk changes.
• estimate refers to functions, according to which the final drying spirality of the sawn timber is estimated based on some physical or chemical variable of the wood, eventually by means of computational tools. Often used for estimation are the earlier drying results of the wood.
• a counter spirality compensating the drying spirality of the sawn timber is sawn to the trunk.
• sawing it is thus possible to take into account the influence of the grain angles of the wood on the dry- ing spirality of the dried sawn timber, which offers a prominent advantage of being able to provide a controlled counter spirality of the sawing blank, whereby the sawn timber made of the sawing blank is straightened and its quality is essentially improved.
• pressure stacking is used during drying for achieving straight timber.
• the grain angles of the sawing blank are gener- ally measured and/or estimated before sawing and immediately after sawing or already during sawing, and based on the mentioned grain angles, the compensation of the drying spirality is adjusted by turning the angle between the sawing plane and the longitudinal section plane defined by the center line of the trunk.
• the grain angle of the cells of the trunk at the sawing point can be measured and the influence of the grain angle on the drying spirality of the sawn timber made of the respective sawing blank can be mathematically calculated and forecast.
• the grain angle is preferably measured immediately after the saw blade like balk chipper.
• the invention also concerns a sawing apparatus for compensating the drying spirality of the sawn timber, whereby the sawing apparatus comprises a feeding device and a receiving device and saw blades.
• the sawing apparatus comprises a measuring device for measuring and/or estimating the grain angles of the trunk.
• the sawing apparatus further comprises a data processing system having means for saving the measured and/or esti- mated grain angles of the trunk and for comparing those with earlier measured grain angles of trunks.
• the counter spirality to the sawing blank can be made either so that the trunk is rolled by means of the feeding and receiving means of the trunk moving system or, alterna- tively, so that the rolling of the trunk is prevented and the log or the trunk is fed to the sawing device the butt or top ahead by means of the trunk moving system, and the saw blade(s) like balk chipper blades turn with respect to the longitudinal section plane defined by the center of the trunk, thus achieving the same result as by rolling the trunk.
• the above-mentioned methods can also be used simultaneously together.
• the total roll- ing angle, by which the trunk has been rolled can preferably be calculated mathematically by measuring the length of path and the speed of the trunk during the sawing, as well as the momentary rolling angle from the angle between the sawing plane and the comparing plane defined by the center line of the trunk used in the comparison.
• the rolling angle of the trunk can also be identified optically by using a reference line drawn onto the end or sides of the trunk.
• the local rolling angle and the total rolling angle calculated thereof can be received by technical, mathematical and mechanical means.
• Figure 1 describes operation of the method in accordance with the present invention, realized with a sawing apparatus in accordance with the invention.
• Figure 2 illustrates the sawn surface achieved by means of the method.
• Figure 3 illustrates the sawing co-ordinate used in the apparatus described in figure 1.
• the (saw) log 1 is brought to the saw table 3 through feeding device 4 of the log moving means.
• blades 2 of the balk chipper and the feeding device 4 and the receiving device 7 of the log moving means saw by means of two blades the trunk into a balk with a certain spirality.
• the spirality of the balk is achieved by rolling the log 1 by means of the feeding device 4 and the receiving device 7 as regards to the sawing plane defined by the blades 2, with respect to the sawing table 3.
• the balk re- ceives a sawn surface turning around the trunk as described in figure 1.
• the sawn surface is described in more detail in figure 2.
• the receiving device 7 can be in its basic design either a roller 9, which can be turned in respect of the sawing plane 6 or a wheelwork 9, which can be rolled along the sawn surface 8.
• the sawing planes are defined by the blades 2 of the balk chipper.
• the spirality is made to the certain trunk length based on the desired rolling angle, where by the turning angle defines the dimension of the counter spirality to be processed to the length of the trunk.
• the sawn surface 8 processed to the balk by means of the apparatus in accordance with figure 1 is illustrated in figure 2.
• the sawn surface 8 turns propeller-like around the centerline L of the trunk, said line being defined by the center point 6 of the sawn balk.
• a line section 11 is defined by the saw blades 2 of figure 1.
• a comparative line segment 10 is defined by the mathematical center point of the trunk. The comparative line segment 10 can be determined e.g. mathematically.
• Angle K is formed between the compara- tive line and the lines defined by blades, said angle expressing how much the sawing plane has rolled compared to the comparative plane defined by the comparative line segment.
• the decision how much and to which direction the log 1 has to be rolled depends on the twisting of the tree during its growth, that is the spiral grain angles and its location in the wood material (heartwood /sapwood) and the differences between the grain angles of the cells. Because the grain angles are mostly measured relatively close to the surface of the trunk or the sawing blank, and the sawn timber is dried later, the influence of the grain angles measured or estimated in a fresh trunk or sawing blank like balk on the spirality of dried sawn timber must be generally estimated.
• the estimation is preferably performed with a data processing system using fuzzy self-learning logic.
• the program must consider at least the respective blade setting, because the sawn timber received of a certain trunk results in different drying spiralities with different sawn timber pieces, depending e.g.
• a self -learning data processing system can be utilized here, for controlling the controlling logic of the angle between the sawing plane and the comparative plane defined by the centerline of the trunk in the sawing process.
• the sawing history of the previous sawing blanks/sawing timber pieces and the drying history and the drying spirality of the sawn timber are taken into account, and, based on the grain angles of the sawing blank or trunk, the drying spirality of the sawn timber is estimated.
• the control logic of the means for changing the angle between the sawing plane and the comparative plane defined by the center line of the trunk, also the outer dimensions of the trunk or the sawing blank and the final drying percentage of the sawn timber must be generally taken into account.
• the total spirality of the trunk can be measured, detected and calculated by using different measuring methods. By means of these measuring values and mathematical formulas and based on programmatic measures, the rolling of the trunk 1 with respect to the sawing plane 6 is performed by using the feeding device 4 and the receiving device 7.
• the instantaneous turning angle between the comparative plane 10 fixed in the trunk and the sawing plane 6 illustrated more clearly in figure 2 is changed, and said rolling angle can be calculated from the angle between the comparative plane and the sawing plane.
• the rolling is performed so that the instantaneous rolling angle is changed evenly, when the trunk moves forward on the sawing line.
• the respective rolling moment, rolling angle and the rolling mechanics is dependent on the mechanical and programmatic solutions of the sawing apparatus and the data processing device and control logic connected thereto (not shown in the drawing).
• the rolling of the log implemented by means of the measuring methods and the meas- uring values based thereon, as well as by means of the feeding device 4 and the receiving device 7, is based on the blade setting, drying degree of the sawn timber, growth speed of the tree, density of the growth rings of the tree, base and top measures, cross- grain, crooked-growth, amount of snags and knots, ovality, coning angle, grain angles of the sapwood and/or heartwood cells, age, summerwood and juvenile wood percent- age, moisture content, temperature of the log, final moisture content of the sawn timber, quality of logs, species of wood, experimental and statistical measuring history and material, as well as on the combinations and/or partial weightings of the above mentioned measuring values.
• the measuring device 5 can be located even in a different room than the saw and the feeding device 4 itself. In that case, how- ever, the measured logs and their measuring information must be saved, and the moving of the logs on the sawing line followed, so that when the log comes to the blades of the balk chipper 2, the respective data and rolling angles can be fed to the feeding device 4 and the receiving device 7.
• the method in accordance with the invention further preferably comprises evaluation of the sawing result, mathematical evaluation, recognition of the sawn spirality and measuring of the grain angles of the cells of the wood immediately after sawing, and, based thereon, eventual readjustment of the rolling of the log by means of the feeding device 4 and the receiving device 7, based on the feed-back.
• the spirally sawn balk can be sawn immediately on the same sawing table or on a separate sawing table to sawn timber, or this sawing can be per- formed later.
• the sawing to sawn timber is performed according to the chosen blade setting.
• the sawn timber has then certain spirality.
• the sawn timber is dried into the chosen drying degree (generally 0-30 %), it is straightened during the drying.
• the receiving device 7 can also be a knife or rail control running on the surface of the log along the sawing line and turned according to the spirality sawn to the log.
• the knife is preferably suitable for total device solutions with a band saw and a rotary saw.
• a balk chipper also other possible saws like band saws and/or rotary saws and/or circular saws can be used.

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8561060

Family Applications (1)

Country Status (6)

Families Citing this family (2)

Citations (3)

• 2001
  • 2001-04-25 FI FI20010865A patent/FI112453B/fi not_active IP Right Cessation
• 2002
  • 2002-04-25 WO PCT/FI2002/000354 patent/WO2002085585A1/en not_active Application Discontinuation
  • 2002-04-25 EP EP02718228A patent/EP1432559B1/de not_active Expired - Lifetime
  • 2002-04-25 AT AT02718228T patent/ATE318684T1/de not_active IP Right Cessation
  • 2002-04-25 RU RU2003134541/03A patent/RU2288836C2/ru not_active IP Right Cessation
  • 2002-04-25 DE DE60209472T patent/DE60209472T2/de not_active Expired - Lifetime

Patent Citations (3)

Also Published As

Similar Documents

Legal Events