AUTOSAW SYSTEM FOR SAWING SIMULATION

Transcription

1 AUTOSAW SYSTEM FOR SAWING SIMULATION C. L. TODOROKI Ministry of Forestry, Forest Researh Institute, Private Bag, Rotorua, New Zealand (Reeived for publiation November 99; revision 9 Deember 99) ABSTRACT A PC-based system, omprising three programs, has been developed to simulate the sawing ofpruned logs. Timber grades, onversions, and values may be produed for both individual logs and bathes of logs. The number of logs whih may be proessed in any given bath is unrestrited. Simulations may be performed either interatively or as part of an automated proess. Automated sessions require 8 to 6 seonds to proess eah log whilst interative sessions, whih provide graphi images of the log at eah stage of the simulation, may be interrupted at any stage. Keywords: omputer simulation; simulated sawing; automated sawing; pruned logs; sawing pattern. INTRODUCTION Computer programs for simulating sawing have been available sine the early 97s. The prominent Best Opening Fae (BOF) system of the USDA Forest Servie (Lewis 98) produes dimensioned timber at the headrig, whilst inorporating a large number of sawmill variables. SIMQUA (Leban & Duhanois 99), a model for simulating wood quality, an simulate the sawing of boards to produe a detailed visual analysis of wood quality. A ommon feature of these two models (and many more) is that the log profile is represented by a series of irular ross-setions. Suh idealised logs, Le., ylindrial logs with a given taper, rook, and other harateristis, rarely exist in the real world. This problem was addressed in part by Lewis (986) when modifiations were made to the BOF system to enable simulation of irregular logs with sweep and elliptial rosssetions, with a onstraint that the axes of eah ellipse be oriented either horizontally or vertially. The modifiations enabled many different log shapes to be simulated but logs were still "idealised". Atual log shapes, or very lose approximations to them, had been implemented earlier by Singmin (978) in his program SIMSAW, whih had been developed to evaluate the effet of sawing patterns on timber reovery from logs. Unfortunately, this was restrited to a limited number of sawing patterns. Oena & Tanhoo (988) also approximated atual log shapes in their graphi log sawing simulator by using polygons to represent the log and defet profiles although they did not address the problem of variations in many sawmill parameters. New Zealand Journal of Forestry Siene (): -48 (99)

2 Todoroki AUTOSAW system for sawing simulation Garia (987) addressed this problem with the implementation of SEES AW, an interative graphi simulator providing detailed visual log analysis and, like BOF, inorporating many sawmill variables whilst using data obtained from the physial sawing of real logs. Eah setion of the log was still, however, represented by irular ross-setions and so it was a natural development to extend the model to inorporate elliptial ross-setions (Todoroki 988). SEESAW proved to be a useful tool for evaluating pruned sawlogs (Park 987) and pruned resoures (Park 989a) and ould also be used to analyse the effet of different sawmill variables. Being an entirely interative tool, deisions made in a real mill ould be imitated at the terminal to simulate the sawing of individual logs. Proessing large numbers of logs to one ormore speifially designed sawsystems (e.g., Park 989b), however, proved to be a very time-onsuming task and required a high level of skill and experienefromthe operator. Even so, initial results often suffered from errors and inonsistenies whih required more time and further simulations to provide orretions. Thus, the need for an automated sawing simulator was reognised and development of the system initiated. SYSTEM COMPONENTS The sawing simulation system omprises three programs AUTOSET, AUTOSAW, SAWNOUT. A general overview of the interation and files assoiated with the three programs is given in Fig.. Files whih have been produed automatially are assigned filenames whih onform to a naming onvention (see below). Filename extensions identify the type of file and are assigned automatially when neessary. User sawing speifiations Log data i Sawn produe AUTOSET x Auto-proessing ommands AUTOSAW y < > Produts bath file A. SAWNOUT J Sawing ommands Simulation history Prie List j Distribution tables FIG. -Interation between the major omponents of the sawing simulation system

3 4 New Zealand Journal of Forestry Siene () Thefirst of the three programs, AUTOSET, allows for the reation and/or modifiation of ommand files whih ontain the speifiations for the sawing strategy and sawing pattern. These ommand files, together with one or more log data files, an be used diretly as input to AUTOSAW, providing automated sawing simulation on the speified logs. The primary output of AUTOSAW is a timber list of dimensioned and graded boards whih are identified by the sequene in whih they were produed and by the log of origin. This timber list is linked to any nominated prielist and proessed in SAWNOUT (Sawn Outturn) to produe tables of onversions, grades, and values for both individual logs and log bathes. The three programs are desribed in more detail below. AUTOSET Program AUTOSET provides user diretives for the seletion of sawing patterns and for the speifiation of sawing strategies. It also overs sawmill variables, some timber grading variables, log positioning, board dimensions, edging, and doking options. Sawmill variables The sawmill variables are the arriage onfiguration, sawkerfs of the headrig and edger, minimum reoverable dimensions, minimum learutting length, doking inrements, overut, and wane tolerane. Timber grades At present the system reognises six timber grades. These, in order of priority, are: Clear (denotedby""infig.,,4,),clear Fae("x"),No. Cuttings("s"),No.Cuttings("f"), Knotty ("k"), and Knotty With Pith ("p"). Either, or both, of the learutting grades may be redefined by the user. The number of learutting grades may be extended in future if the need arises. Log positioning The log may be positioned with either the small end or the large end presented to the saw. It may be either entred on the arriage or positioned at a user-speified distane from the front knee. Positioning for either half-taper or offset sawing is also atered for, as is positioning for sweep. Five basi options are provided for positioning for sweep horns up, horns down, horns in, horns out, and rotation from horns down. The last option uses a userspeified angle to rotate the logfromthe horns down position. For example, with an angle of the log will be in the same position as had the horns down option been seleted; with an angle of 4 the log will be positioned suh that it is halfway between the horns down and horns in positions. Board dimensions There may be up to width lasses and four thikness lasses speified for eah sawing pattern. Eah thikness/width lass requires an atual and a nominal thikness/width to be speified to aommodate overutting.

4 Todoroki AUTOS AW system for sawing simulation FIG. -Example of "live" sawing. Grades are FIG. -Example of "ant" sawing (three sides), "" Clear; "x" Clear Fae; "s" No.l Grades as for Fig.. Cuttings; "f" No. Cuttings; "k" Knotty; "p" Knotty With Pith. LOG : TAS TK4.DAT automatially sawn with demo.aut FIG. 4-Example of "ant" sawing (four sides). FIG. -Example of "free ant" sawing. Grades Grades as for Fig.. as for Fig.. Edging options At the time of writing, two possibilities for automated edging exist. These are edging for length and edging for width. Both options make use of the above width lasses. (With the former option seleted, the AUTOS AW program maximises volume under a length onstraint whilst the latter maximises volume under a width onstraint.) Sawing patterns The AUTOSET program has provision for both "ant" sawing and "live" sawing patterns. Many variations on these sawing patterns are possible. In addition, ant sawing patterns an

5 6 New Zealand Journal of Forestry Siene () also be set up to enable the simulation of both automatially entred ants and free ants. Free ants require the seeking out of the position of the defet ore. This is aommodated in the AUTOSET program by speifying a grade for eah of the two sides of the ant. After the grade for eah of the sides has been enountered (or exeeded) during the sawing simulation the appropriate ant size is seleted and any neessary sizing uts made. Results after simulation using various sawing patterns are demonstrated in Fig. - a "live" sawn log in Fig., "free ant" sawing in Fig., and "entred ant" sawing in Fig. and 4. Some of the variations possible in the number of log faes are also indiated, with the sawing sequene and diretion indiated by the flith numbers. Cant sizes There may be up to five ant thikness lasses speified. Eah thikness lass requires an atual and a nominal thikness to be speified, as for board dimensions. If the ant size is to be determined by the small-end diameter of the log, then small-end diameters orresponding to those ant sizes must be entered. Sawing strategies Separate sawing strategies an be defined for eah side of the sawing pattern enompassing suh onsiderations as seletion of the opening ut, board thiknesses, inremental thikness hanges, minimisation of wastage, and the riteria for turning the log to the next fae. In addition, the following variations are possible. Opening uts: The opening ut an be speified at a ertain position (determined by the dimensions of the fae exposed to the saw) or at a position relative to the opposite fae. The latter option makes provision for emulating the sawing of the opposite fae, or for sawing boards of speifi thiknesses upon meeting a dimensions onstraint, or for maximising the boards' volume, or for maximising reovery for boardsfromthe ant. Board thiknesses and inremental hanges: Any or all of the board thiknesses inluded in the board dimensions speifiations may be used for sawing on eah fae. Inremental thikness hanges may be speified to our at a position determined by either the dimensions or the grade of the fae exposed to the saw. Sizing uts I minimisation of wastage: The ombination of sawing pattern and sawing strategy may reate wastage on some faes. For eah of these faes it is possible to elet to have wasteage minimised by allowing for alternative board thiknesses to be substituted. Turning the log: Criteria for turning the log an be speified suh that sawing of the exposed fae is to ease if a speified dimension of fae or grade is enountered, or exeeded, or after a speified number of flithes have been reovered. Auto-proessing Commands File This small but signifiant program module provides for the reation of new Autoproessing Commands Files, or the modifiation of previous ones. The Auto-proessing Commands File (Fig. ) ontains referene to the Sawing Commands File and also ontains the number and filename of eah of the logs to be proessed by the sawing simulator, AUTOSAW.

6 Todoroki AUTOSAW system for sawing simulation 7 AUTOSET summary The previous subsetions desribe the Sawing Commands File. Thesefilesmay be saved, or manipulated to imitate different sawing strategies, sawing patterns, and variations in mill parameters. Referene to the Sawing Commands File and to eah of the log datafiles is stored in the Auto-proessing Commands File. AUTOSAW Program AUTOSAW may be used for both automated and interative sawing simulations. An overview of the AUTOSAW program is given in Fig. 6 in more detail than was given in Fig.. For automated sawing simulations, an Auto-proessing Command File ontains diretives to the appropriate sawing strategy speifiations file and log data files. On the other hand, interative sawing simulations require interative use of funtion keys, with the user making deisions at eah stage of the simulation, similar to those deisions made in a real mill. Both modes of operation provide sawing, edging, doking, and grading apabilities. Log desription Log data files ontain desriptions of the log profile and defet ore measured in two planes. The external log profile is represented by elliptial ross-setions (Todoroki 988) whilst whorls are represented as polygons (Garia 987). fautosavlt ) Log data Simulation history i / \\ 4, < *,, f^~ I Sawn produe i I Simulation history Interative proessing Autoproessing ommands I Ii Automated proessing L ^ Produts bath I Log I data Log n data y i Sawn I I Sawn n produe j T produe» > Simulation history FIG. 6-An overview of the AUTOSAW program. J Simulation j history n t

7 8 New Zealand Journal of Forestry Siene () Data were aquiredfromthe physial sawing of real logs, desribed in more detail by Park (987). Display layout In the automati mode, a diagram showing the flithes whih have been ut and eah grade reoveredfromeah flith piee, is displayed on the sreen as eah log is proessed (Fig. - ). For the interative mode the display sreen is divided intofivepanels (Fig. 7). All but the information panel may be enlarged. Enlargements of the two sides of a flith are shown in Fig. 8 and 9. Sawmill variables, timber grades, log positioning All sawmill variables, timber grades, and the log positioning are automatially assigned (with the values ontained in the Sawing Commands File) for the automati mode of AUTOS AW. For interative sessions, these variables are assigned with default values whih may be altered and/or viewed during the simulation session. Sawing, resawing, edging, doking, and grading For interative use, 66 funtion keys are available for eah of the sawing, resawing, edging, doking, and grading modes. Capabilites of these funtion keys inlude: repositioning of arriage knees; moving the sawing, resawing, edging, and doking sawlines; utting in any ofthe modes; unutting (to undo previous uts); volume alulations; lear length alulations; display sreen panel seletion; flith seletion; both automati and interative edging, Top view AUTOSAW Inner fae Log : OT Length: mm s.e.d.: 64 mm l.e.d.: 69 mm &7- "." Outer fae Flith # Thik: 6.mm Skew: deg '66,7 "."" FIG. 7-The five-panel display sreen.

8 Todoroki AUTOSAW system for sawing simulation 9 log : demo Flith 8 Thik :4.mm Skew: deg Width :.mm 48 Outer fae 48 FIG. 8-Example of edging simulation (for length) on a flith. log : demo Flith 8 Thik : 4.mm Skew : deg Width : 8.mm 444 Outer fae 444 FIG. 9-Example of edging simulation (for width) on a flith. doking, and grading; and many more. In eah mode, some funtion keys are available for assignment, thus there is still room for expansion should the need arise.

9 4 New Zealand Journal of Forestry Siene () Some of the funtion keys are desribed in more detail below. Automati edging: The omplexity and number of iterations required to perform the automati edging routine is, to a degree, dependent on the shape of theflith.ten routines (for eah of the two types of edging as desribed in the AUTOSET program) are used to edge aflithwith up to seven routines being used on an "irregular" shapedflithand up to three routines for a "regular" shapedflith.for simpliity, a "regular"flith is one for whih 66% or more of one of the edges is straight. After theflithhas been automatially edged, the program automatially performs the doking and grading routines using the speified variables. An example of a flith whih has been automatially edged (for length), doked, and graded is shown in Fig. 8. For omparison, the same flith automatially edged for width is shown in Fig. 9. Resawing: Resawing is, at present, possible only in the interative mode but will, in the future, be inluded as a ommand (or series of ommands) in the autoproessing ommand file (via AUTOSET). Two resaws are implemented and a resaw kerf an be speified for eah resaw. To indiate that the board has been resawn, shading is used in the produts diagram (Fig. ). FIG. -Example of resawn boards in a log. Outputs Three types of files may be reated the Sawn Produe File, the Simulation History File, and the Produts Bath File (Fig. 6). The Sawn Produe File is a timber list of dimensioned and graded boards whih are identified by the sequene in whih they were produed and by the log of origin. The Simulation History File is a binary struture file whih stores a

10 Todoroki AUTOSAW system for sawing simulation 4 omplete reord of the sawing simulation session. It is produed for eah log whih is automatially sawn and is optional for interative simulations. When used as input to AUTOSAW (see Fig. 6), this file provides a omplete visual reord of the simulation. The log's sawpattern an be viewed (Fig. - and ) as an individual flithes (Fig. 8and9)and, in fat, any panel of the display sreen may be viewed. In addition to viewing the simulation's history, it is also possible to ontinue with the sawing simulation (had it not been ompleted during an interative session) or even to ompletely alter the previous session by using the funtion keys. The Produts Bath File is reated only for the automated simulation. Thisfilean be used diretly as input to the SAWNOUT program (desribed below) and inludes a referene to eah of the Sawn Produe Files. Also inluded is the volume for eah log of origin. This is required for alulation of onversions, volume residues, and learut length ratios in the SAWNOUT program. Eah log volume is alulated using trunated ones up to.4 m from the large end, and thereafter paraboloids. Naming onventions The files represented in Fig. and 6 have the following extensions. FILE TYPE Log Data Sawn Produe Simulation History Sawing Commands Auto-proessing Commands Produts Bath Prie List Distribution Tables ETENSION.DAT.OUT.CON.LIV/.CAN.AUT.SWN.PCE.LIS For automated simulations the resultant output files are assigned names whih identify the Auto-proessing Commands File from whih they were reated and the log of origin (by sequene number). The number is restrited to two digits thus up to unique filenames for eah type of file and for eah automated simulation are possible. This is more than suffiient for present purposes. Operation time Beause the logs to be sawn ontain varying degrees of omplexity, i.e., the number of log setions and number of defets (pith and whorls) differ from log to log, in addition to the variation possible in the atual sawpattern, no one time an be representative for the model. However, trials of logs have produed times of between 6: min (all logs having four setions only) and : min (all logs having setions), Le., 7.8 and.8 s/log, respetively. Times an be redued further (by % or more) by not having the map of the sawing pattern and board grades displayed on the sreen for eah log as it is sawn. Sawn Outturn Program Program S AWNOUT analyses the results of the sawing studies. Individual log onversions and/or aumulated log onversions an be alulated. The 4 tables available for analysis are shown in Appendix. Tables may also be further subdivided into thikness lasses.

11 4 New Zealand Journal of Forestry Siene () The S AWNOUT program requires input of a Prie List whih may be reated or edited within the body of the program. Other input files (e.g., the Produts Bath file from the AUTOSAW program) or individual sawn produe files an also be edited within the program, and a further faility allows real mill data to be entered diretly at the keyboard. Hardware and Software Considerations AH three programs run on IBM-ompatible PCs under the MS-DOS operating system, are oded in Pasal, and ompiled using the Mirosoft Compiler. The AUTOSAW program is linked with the HALO graphis library, thus a graphis ard is required. A printer is optional. APPLICATION AND FUTURE DEVELOPMENT AUTOSAW, in onjuntion with SAWNOUT, is already proving useful for rapid evaluation of pruned sawlogs as affeted by log positioning, sawpattern, and sawing, edging, and doking proedures. Any number of simulations may be applied to individual logs providing extensive failities for evaluating the outome of variations in sawing and sawmill parameters. As well as the obvious advantage provided by greatly inreased performane, the simulation pakage provides the user with a onsistent, reproduible model whilst still giving the flexibility and ontrol required in the speifiation of parameters. It is envisaged that AUTOSAW will be developed further, expanding its range of apabilities and flexibilty, with partiular emphasis on areas suh as edging and grading. The automated edging routines are the present limitations of the program and this problem will be addressed by implementation of a routine whih will edge for speifi board dimensions based on order of priority for the given sizes. Options for edging for grade are also planned. ACKNOWLEDGMENTS The development ideas of J. Park and his in-depth knowledge of milling praties have been entral to the development of the simulation pakage. The valuable ontributions and program validation by S. Wakelin are also gratefully aknowledged. REFERENCES GARCIA,.987: SEESAW: A visual sawing simulator. Part II: The SEESAW omputer program. Pp. 7-6 in Kininmonth, J. A. (Comp.) "Proeedings of the Conversion Planning Conferene". Ministry of Forestry, FRI Bulletin No. 8. LEBAN J.M.; DUCHANOIS, G. 99: SIMQUA: Un logiiel de simulation de Ia qualite" du bois. Annales des Sienes Foresteriires 47: LEWIS D.W. 98: Sawmill simulation and the Best Opening Fae system: A user's guide. USDA Forest Servie, Forest Produts Laboratory, General Tehnial Report FPL : Best Opening Fae system for sweepy, eentri logs: A user's guide. USDA Forest Servie, Forest Produts Laboratory, General Tehnial Report FPL-49. OCCENA, L.G.; TANCHOCO, J.M.A. 988: Computer graphis simulation of hardwood log sawing. Forest Produts Journal 8(): 7-6.

12 Todoroki AUTOSAW system for sawing simulation 4 PARK, J.C. 987: SEESAW: A visual sawing simulator. Part I: Data, methods, and program evaluation. Pp in Kininmonth, J. A. (Comp.) "Proeedings of the Conversion Planning Conferene". Ministry of Forestry, FRI Bulletin No a: Appliations of the SEESAW simulator and Pruned Log Index to pruned resoure evaluations A ase study. New Zealand Journal of Forestry Siene 9: b: Comparison, via the SEESAW simulator, of three sawing systems for pruned logs. New Zealand Journal of Forestry Siene 9: PARK, J.C; LEMAN, CS. 98: A sawing study method for evaluating timber from pruned logs. New Zealand Forest Servie, FRI Bulletin No. 47. SIGMIN, M. 978: SIMSAW A simulation program to evaluate the effet of sawing patterns on log reovery. Counil for Sientifi and Industrial Researh Pretoria, Speial Report HOUT6. TODOROKI, CL. 988: SEESAW: A visual sawing simulator, as developed in Version.. New Zealand Journal of Forestry Siene 8:6-.

13 44 New Zealand Journal of Forestry Siene () APPENDI PRICE LIST. WASTE CREDIT $ 4 Grade Width (mm) Pith Knotty No. Cuttings No.l Cuttings C Fae Clear Clearuts GRADES AND THEIR RESPECTIVE ZONES Grade Code Zone Pith Knotty No. Cuttings No.l Cuttings C Fae Clear P k f s a b b b AUTOSAW V. DEMA.AUT RUN WITH DEMA.CAN THICKNESS : mm Grade Pith Knotty No. Cutt's No.l Cutt's C Fae Clear Total TABLE Grade by sizes sawn, number, and volume (vol. = m x IO" ) for log No Width (mm) Total

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15 46 New Zealand Journal of Forestry Siene () TABLE -Surfae area and volumes of boards for log No. Board Surfae area of fae and edge Grade Board volumes ra D ra C ra B ra A ra 4D ra 4C ra 4B ra 4A ra D ra C ra B raa ra 6D ra 6C ra 6B ra 6A ra 7B ra 7A ra 8C ra 8B ra 8A rab raa rab raa rab raa rab raa raa ra6b ra6a ra7a ra8a ra9a raa raa raa raa ra4a raa ra6a ra7a Area (m ) Surfae area sawn <%) L f k p k p Volume (m x IO" ) Perentage of log volume

16 Todoroki AUTOSAW system for sawing simulation 47 TABLE 6-Summary of all logs in study grades by number and volume (m x IO" ) of sizes sawn Grade Pith Knotty No. Cuttings No.l Cuttings CI Fae Clear Total Width (mm) Total TABLE 7-Grade outturn and value Log No. P k f s Sawn vol. (m x IO- ) Value ($) Log vol. (m x IO" ) Log No. P TABLE 8-Grade outturn as a perentage of round log volume k f s Conversion (%) TABLE 9-Values per ubi metre Log No. $/m sawn Residue $/m round VoL $"""

17 48 New Zealand Journal of Forestry Siene () Log No. TABLE -Number and volume of learuttings (vol. = m x ~ ) Length lass (m) Total Log No. TABLE II- Volume of learuttings as a perentage of round log volume Length lass (m) Total TABLE -Reoverable lear lengths as a perentage of round log volume Log No. _ "~"l8~~~ Length lass (dm) "6 "4"""" "To 7 "" TABLE -Total surfae area (m ) of sawn timber by log zone Log No. Sawn volume Zone a Zoneb Zone Total (m xlo- ) TABLE 4-Log number and original log identifiation Log No. Log ID ra TAS kgl