BANDSAW APPARATUS AND METHOD OF OPERATION

Abstract: A method of operating a bandsaw is disclosed. By stopping a bandsaw between saw cuts it is possible to reduce fatigue in wide bandsaw blades significantly. This, and a gullet (3.04) stress reduction strategy have resulted in a sixty three percent increase in bandsaw blade thickness (1.04, 2.02) for a given wheel diameter (2.05) while maintaining high strain. To achieve this it is necessary to redesign the bandsaw. To that end, descriptions of three bandsaw drive systems are described along with the required band wheel modifications.

Description: Bandsaw Apparatus and Method of Operation Background of the invention Field of the invention This invention relates to bandsaws and more particularly is directed towards reducing the size of band wheels for a given application via an improved method of operation Description of the prior art Bandsaws come in a huge variety of sizes. Blade widths 3.03 vary from a few millimetres to 0 4 metres or more. Band wheel diameters 2.05 vary from 0.4 metres to 3 metres or more in diameter. Power requirements vary from less than 1 kilowatt to in excess of 150 kilowatts. One thing that all bandsaws have in common is the blades fatigue as a consequence of spinning around the band wheels 2.01 Tins can lead to cracking m the saw gullets 3.04 and subsequent blade failure The factors that result in an increased level of fatigue m bandsaw blades 1.01 and 3.01 and 2.07 are listed below. 1 : Thicker gauge of blade (t) 1.04 and 2.02 for a given band wheel diameter 2: Higher bandsaw blade strain 3: Running bandsaw blade too long 4: Misalignment of the band wheels 5: Poorly machined band wheels 6: Misalignment of the saw guides 2.06 and 4.09 7: Saw guides that are not flat 8: Misalignment of the saw head relative to the cutting direction 9: Poor tracking of bandsaw blade on band wheel 10: Incorrect bandsaw blade tension 11 : Uneven grinding of bandsaw blade 12: Stress concentranon points in bottom of saw gullet 13- Attempting to cut too fast 14: Cutting with a blunt blade 15: Excessive hook angle 3.02 16 Vibration m bandsaw or saw blade All these factors are extremely important. All but 1. 2, 3 and 12 will cause poor cutting. Note that 3 and 14 are not the same. A bandsaw blade may have spent a lot of time spinning and not cutting and/or cutting a soft timber that blunts the saw at a slower rate. Factors 1 and 2 actually improve performance, a thicker more stable blade permits a deeper gullet, which can hold more sawdust, allowing faster cutting. As a rule saw gullet depth and consequently gullet volume increase in propoπion to the saw gauge. .All the literature that I am aware of limits the thickness of the bandsaw blade to roughly 1/1000 of the diameter of the band wheel, a ratio (R) of 0 001 Traditionally. strain was set in proportion to the cross sectional area of the saw blade (W.t). Modern strain theory has turned this on its head. The relationship is now inverted This is the result of attempts to quannfy the amount of strain due to the blade bending around the band wheel Thus modern thin kerf high strain saws came into being Reducing die blade thickness to wheel diameter ratio to R = 0 000583 allowed in excess of a ten fold increase in cross sectional area blade strain The ceiling on R remamed at 0 001 Although I know of some operators pushing that ceiling by 10% (R = 0 0011 ) Inside 5 this range there are operators who are having problems with cracking and there are those that aren ' t Machines running narrow blades (under 50mm wide and occasionally as wide as 75mm) present a different set of problems Narrow blades may significantly exceed the thickness test shown above because they are cheap and consequently may be 10 considered disposable Manufacturers of narrow bladed machines talk terms of 'blade flex life " This is an admission that blades have a limited life in their application It is uncommon to find these blades being sharpened more than twenty times in their life Nor will they run for anywhere near as long between sharpenings Typically in Australia, cutting hardwood, these blades will fail after one days cutting i 5 Consequently they aren t exposed to the same level of fatigue as a wide band, which may be sharpened a hundred nines or more and run for a hundred days duπng its life The cost of these narrow blades are typically less than 10% of the cost of blades for a bandsaw running wide blades Narrow blades are mass produced, smaller and have teeth that are set side to side, whereas wide blades are custom built and have swaged. 0 stellite or tungsten teeth Cutting rates and accuracy are influenced by the cross section area of the saw gullet 3.04 The wider the saw cut the larger the gullet must be If the gullet area is too small sawdust may overflow in the cut causing heatmg and wandering of the saw blade The solution to this is to slow the cutting rate This results in a finer sawdust and 5 premature blunting of the blade The finer sawdust falls out of the gullet m the cut and may also interfere with saw tracking The gullet depth is limited by the thickness of the saw blade Too deep a gullet and the tooth will be weakened Disposable narrow blades are not a solution to the problem of fatigue in wide bandsaw blades The blades do not have the stability to cut as wide or as fast as wide 0 blades Nor will they cut Australian hardwoods as successfully (if at all) Narrow bladed bandsaw mills have become popular through lower capital cost Narrow bladed mobile bandsaws have previously been described with brake and clutch systems to stop the blade These are small machines The wheels at a guess may weigh less than 20kg All have been developed for safety not performance Their 5 aim is to bπng the blade to a stop m a matter of seconds not minutes In LiS patent number 4559858 a brake and clutch svstem is descπbed The only suggested benefit is safety This patent doesn t refer to narrow bladed machines however the onlv manifestations have been narrow bladed machines Further more a reference ' 14 hp petrol motor should for mobile applications " indicates the rntennon 0 is for low Dower applications At first glance it would appear that the brake and clutch descπption gives broad coverage .An earlier L S patent 4275632 describes a clutch to facilitate stopping the saw This effectively narrows the scope of US patent 4559858 to the specific lavout described Another proposal. LS patent number 3954037 suggested that driving the bandsaw 5 blade with a linear electric motor here the blade becomes the armature, would allow wheel size to be reduced because blade gπp on the band wheel becomes less important This fails to recognize the importance of fatigue in wide bandsaw blades It would be unpractical to reduce wheel size without a fatigue reduction strategy Tins aside, I have never found wheel gπp to be a problem with bandsaws This is certainly not an issue with high strain svstems We are left with a situation where cutting dense hardwood, or cutting faster or wider, with a high level of performance, can only be accomplished with a wider, heavier gauge blade Tins requires a lareer oand wheel This would appear to be the mitins factor in bandsaw performance Brief description of the drawings Figure 1 Demonstration of the effect that bending around a bandsaw wheel has on a bandsaw blade Figure 2 Representation of the forces involved in developing blade strain and the relationship between bandsaw blade and band wheel Figure 3 Plan view of bandsaw blade Figure 4 Perspective view of bandsaw with automotive dπve tram Figure 5 Perspective view of bandsaw saw head Figure 6 Perspective view of bandsaw with hydraulic power plant References 1 Small sawmill handbook Joseph Denig 1993 Sumiϋarv of the invention This summary includes an outline of the theory and practice associated with this invention This mvention features a method of operating a wide bladed bandsaw that has developed from a bandsaw blade fatigue reduction strategy The result of which is that the limiting factor m bandsaw operation, the ratio of bandsaw blade thickness to band wheel diameter (R) has been significantly increased An analysis of the effect of strain on saw blade fatigue is necessarv Previously bendine strain (σ n e - ) and the strain produced b\ tι-ιhtemn_. the saw blade (σ t ) were used to come up with a universal formula for matching a bandsaw blade to a band wheel σ πe*. = Et/D σ , = F/2A where E = modulus of elasticity = 20 000 kilopascals / mπr t = blade thickness (mm) 1.04. 2.02 D = wheel diameter (mm) 2.05 F = wheel force (kilopascals) 2.03 A = blade width (Vs ) \ blade thickness (t) (mm " ) The net result of tins that where the ratio of bandsaw blade thickness to band wheel diameter (R = t/D) is limited to 0 001 then bending strain σ , le = Et 7 D = 20 000 \ 0 001 = 20 kilopascals / mm " = 196 Newtons ' mm " (N / mm " ) This is applied to all wide bandsaws With combined blade strain (σ tlex - σ t ) never exceedmg 551 N / mm " (and conventionally far less than) it is clear that the combmed strain is far below the ultimate tensile strength of the blade steel 1500 N / mm 2 This would mdicate that the combmed strain (σ _ le \ - σ t ) is limited by stress concentranons in the gullet of the bandsaw blade, as this is where bandsaws crack and fail Figure 1 shows a bandsaw blade. 1.01 bendmg around a band wheel 1.02 and 1.03 show the blade in tension and compression respectively 2.04 shows the blade strain (σ t ) A lot of our efforts are concentrated on reducing stress concentrations in the gullet of the bandsaw blade b> firstlv ensuπng that the bottom of the blade gullet does not have a tight radius and is substantially flat and secondly that the bottom of the gullet has gnnding marks removed either bv reaming or some means of polishing The problem of stress concentrations in the gullet of the bandsaw blade is further complicated by the effect of blade spm time on accumulated fatigue in bandsaw blades An analysis of the time duπng which the blade is spinnmg that is spent cutting is useful Tins will be shown as a percentage (T) Most bandsaws at least have down time returning to the start position and repositioning for the next cut (T=50%) If left runnmg duπng log turning (T=35%) and log loading (T=20%) down nme mcreases further If the bandsaw is left runnmg continuously, eighty percent of the accumulated fatigue associated with bendmg around the band wheels is generated while not cutting Thus accumulated fatigue is being produced unnecessarily These figures are a rough guide and can vary dramatically m different situations To limit this fatigue accumulation it is essential that the bandsaw be stopped between cuts To effect this method it is necessary to fundamentally redesign the bandsaw Conventionally band wheels are built heavily from cast iron for dimensional stability The dπve wheel 4.07 is generally built much more heavily than the dπven wheel 4.11 to produce a flywheel effect Reduced band wheel weight is achieved through a different method of construction It is recommended that the wheels are fabπcated m steel (possibly high grades such as bisalloy) or aluminiu or cast from aluminium If the wheel can be made small enough cast iron may be possible Bandsaws. designed to facilitate this method of operation, with reduced band wheel diameter and weight, and power plants that permit fast start up and shut down of the bandsaw- are a cπtical part of this invention Three apparatuses are descπbed. one with an automotive dπve train, one is hydrauhcally dπven and the last is powered an electπc motor with a pneumatically activated clutch and brake- Reducing the diameter and weight of the band wheels for a given application will allow the power required for fast start up of the bandsaw to be better matched to the power required for cuttmg. Qiucklv stoppmg the bandsaw is also enabled bv the band wheel weight reduction Trials with 17 gauge blades . I 467mm thick), run for 12 months on band wheels of 900 mm diameter, a ratio of R = 0 00163. have resulted in only one small crack and no blade failures 1 he crack was half wav up the back of the tooth where the saw blade was joined Firstly the crack was not m the bottom of the gullet, the point of major stress concentration Secondly being at the join in the blade and having only happened once it indicates that the crack was caused by a manufactunng fault in the blade Either the weld had been ground to thm or the weld had a fault in it The crack was repaired and did not reoccur Blades on average have been on the saw for between 5 and 20 hours between sharpenmgs. cuttmg both hardwood and softwood until blunt These blades are all stelhte tipped Stel te is a hard mateπal that mamtams a sharp edge longer This works against fatigue reduction as cutting time and therefore blade spin time are increased The loss of the flywheel effect from heavy cast iron band heels appears not to be a problem at all Tπalling of a 16 gauge blade ( a ratio of R = 0 00183. was considered No benefit would have been gamed from this, as the prototype machme now needs a power upgrade Blade speed for cutting widths between 1000mm and 1350mm has been reduced to 22 metres per second (normally 35 m/sec) Nevertheless it is possible to extrapolate from diese figures diat 16 gauge would work for dense, abrasive timbers as blades would only stay on the saw a short time Note that earned to the extreme it mav become necessary to grind the back edge of the saw occasionally to prevent cracking Note that only a lack of power prevents us runmng higher blade speeds for naπow cutting Blade speed is adjusted via the automotive gearbox to facilitate maximum saw chip size Extremely high strain has been mamtained through out this exercise Stram is an important function in bandsaw performance Stram is the amount of force used to push one band wheel away from the other This is done to make the blade as stiff as possible m the cut Conventionally with a blade thickness to wheel diameter ratio of 0 001 σ 196 N / mm 2 and σ t = 34 3 N / mm 2 High stram studies by F E en' show the following results 20 gauge blade (0 889 mm) on a wheel of 1524 mm diameter σ fl e x = 114 N / mm " and σ t = 411 N / mm 2 17 gauge blade ( 1 467 mm ) on a wheel of 1524 mm diameter σ n e x = 189 N / mm 2 and σ , = 148 N / mm 2 A modest reduction m σ results in a staggering increase m σ t Our results are shown below T = 1 467 mm D = 900 mm F = 1 1336 ke A = 242 mm " σ fl ex = Et/D = 32 6 kp ' mm 2 = 321 ^ ' mm 2 σ t = F'2A = 23 4 kp / mm 2 = 230 N / mm 2 What is clear from these results is that we have been able to maintain very high saw stram ( σ . ) m the presence of a bending stram ( σ t ι e\ ) apparently never achieved before It is quite clear that we are still operating m a zone well below the ultimate tensile strength of the blade steel 1500 N / mm " This process clearlv allows at least a 63% mcrease m blade thickness for our application 1 The above statement could however read This process clearly allows at least a 38 7% reduction in band wheel diameter for our application 1 The resulting lift in cutting performance and quality has been outstanding Other benefits become apparent Smaller band wheels allow the machine to be brought up to speed quicker for a given power input A given braking system will also stop the bandsaw quicker The capital cost of sawmill plant can be reduced significantly The cost of blades is reduced, as they are shorter Any future advances in steel toughness potentially allowing conventional mills to run thicker gauge blades will benefit our process equally Description of the preferred embodiments This description does not set out to descπbe a complete bandsaw Only those parts that relate to the method of operation and the apparatuses designed to effect the method of operation are descπbed A method of operation of a bandsaw. A bandsaw of the type compπsing a dπve wheel 4.07 and at least one dπven wheel 4.11, has entrained over it, a bandsaw blade of a width no less than 85mm. where the ratio of bandsaw blade thickness to band wheel diameter exceeds 0 00135 Where future advances m steel toughness, allow bandsaws to run a thicker gauge blade for a given wheel diameter increasing the conventional limit of blade thickness to band wheel diameter from 0 001. then the ratio of blade thickness to band wheel diameter should exceed that new limit by 35 percent The width of the bandsaw blade is measured from the back edge of the blade to the bottom of the gullet 3.03, and m the case of a double cut bandsaw blade the width should be measured between opposing gullets The means of dπvmg the bandsaw dπve wheel and the means of braking the saw should facilitate acceleration and deceleration of the band wheels and bandsaw blade at such a rate that will allow the blade to be run up to operating speed in less than 2 5 seconds and stopped agam in the same time frame Reducmg the weight of the band wheels for a given application will allow the power required for fast start up of the bandsaw to be better matched to the power required for cuttmg Quickly stopping the bandsaw is also enabled by the band wheel weight reduction This method of operation mcludes the following steps A force is applied to the slide mechamsm 4.08 of the dπven bandsaw wheel 4.11. thus applying strain to the bandsaw blade The amount of force that can be applied is 2 x 230 x W x 0 00163 D Newtons where W and D are respectively the width of the saw 2.02 blade and the diameter of the band wheel 2.05 The first step is to position the log or timber for cuttmg. which may include movmg the bandsaw Secondly, it is necessary to engage the means of dπvmg the bandsaw dπve wheel to spm the bandsaw up to operating speed Then, a cut is made through the log or timber Next by usmg the means of braking, the bandsaw may be stopped or slowed To complete the cvcle one of the next two steps occurs ( 1 ) The bandsaw or log or timber is repositioned to effect the next cut (2) The next log or piece of timber is positioned for cutting This may include moving the bandsaw Where more than one bandsaw blade is cuttmg the timber it may be necessary between cuts to reposition bandsaws relative to each other These steps are a means of reducing handsaw blade fatigue allowing the blade tn keep cutting until it is no longer sha enough to cut, without placing a time limit on the blade being on the saw Thus deliverm?. a service life tn the blade that allows the blade to be used until sharpening renders it too narrow for efficient use. The method of operation will still succeed when the ratio of handsaw blade thickness to band wheel diameter is increased to 0.00163 and blade strain is set to σ , = 230 N 1 The means of reducing bandsaw blade fatigue is aided bv a gullet stress reduction strategy which involves reducing stress concentrations in the gullet 3.04 of the handsaw blade bv firstly ensuring that the bottom of the blade gullet does not have a tight radius and is substantially flat and secondly that the bottom of the gullet has grinding marks removed either bv reaming or some means of polishing. These apparatuses are significant developments in themselves and can stand alone as inventions. In no way do these apparatuses limit the scope of the method of operation of a bandsaw. They do however illustrate the practical resolution of the problem of fatigue in bandsaw blades. Note that only those parts of the specific embodiment that relate to the process described above are detailed below. This is because the complete machine may assume one of many forms. A description of the automotive drive train The means of driving the bandsaw comprises an entire automotive drive train including motor 4.01, clutch and gearbox 4.02, tail shaft 4.03, differential 4.04, axle 4-05. brake and hub 4,06 and control means The automotive drive tram may be left in its chassis with the axle housing attached directly to the chassis. Locking or welding the differential centre allows all drive force to be directed to one axle. The gearbox can be shifted to neutral allowing the drive to be disengaged so that the clutch may be released. The control means includes means for controlling engine throttle, clutch, gearbox and brake. The clutch and brake can be controlled by one pedal and the same master cylinder The hub can alternatively he attached to the handsaw drive 5,01 shaft by means of a coupling capable absorbing some degree of misalignment, or the band wheel may be attached directly to the hub Bv selecting a gear then releasing pressure from the clutch and brake nedal. the clutch is activated and the brake released. Allowing the bandsaw to be accelerated up to operating speed by applying the throttle. Applying pressure to the clutch and brake pedal releases the clutch and applies the brake, thus stopping the bandsaw. A description of the hvdraulic power plant The power plant supplying power to the hvdraulic pump 6.02 mav be an electric or internal combustion motor. The hydraulic pump via a control valve 6.04 drives the hvdraulic motor 6.03. The hvdraulic motor is mounted directly on the band wheel drive shaft 5.01 or alternatively drives the band wheel drive shaft via a gearbox or other reduction device The hydraulic control valve can he used as a brake to stop the saw. The hydraulic control valve directs hydraulic oil from the pump to the tank while not cutting. The hydraulic control valve may be controlled directly or remotely by the operator, or by computer set works. Λ. description of the electric motor with pneumatic clutch and brake An electπc motor will overheat if stopped and started as often as this method requires It is necessary to continuously run the electπc motor and release the dπve via a clutch and brake This has already been descπbed in the form of the hydraulic apparatus above Another way of achieving this is with a pneumatic clutch and pneumatically activated brake This allows the dπve to be released and the bandsaw stopped without stoppmg the electπc motor The electπc motor and clutch and brake assembly are mounted directly on the band wheel dπve shaft or alternatively dπve the band wheel dπve shaft via a gearbox or other reduction device The pneumatic control valves may be controlled directly or remotely by the operator, or by computer set works

Claims: The claims defining the invention are as follows: 1 A method of operation of a bandsaw of the type compπsmg (a) a dπve wheel and at least one dπven wheel, entrained over which is (b) a bandsaw blade of a width no less than 85mm. (c) where the ratio of bandsaw blade thickness to the diameter of the largest band wheel exceeds 0 00135, or (d) where future advances in steel toughness, allow bandsaws to run a thicker gauge blade for a given wheel diameter, increasing the conventional limit of blade thickness to band wheel diameter from 0 001. then the ratio of blade thickness to band wheel diameter must exceed that new limit by 35 percent. (e) a means of applying stram to the bandsaw blade. (f) a means of driving the bandsaw dπve wheel and (g) a means of braking the bandsaw mcludmg the steps of (h ) positioning die log or timber for cuttmg, which may include moving the bandsaw, ( l ) engaging the dπve means to spin the bandsaw up to operating speed, (j) effecting a cut through the timber. (k) usmg the means of braking to stop or slow the bandsaw. (1) repositioning the bandsaw or log or timber to effect the next cut, or positioning the next log or timber, which may mclude moving the bandsaw. and (m)where more than one bandsaw blade is cutting the timber it may be necessary between cuts to reposition bandsaws relative to each other, these steps are a means of reducing bandsaw blade fatigue, they allow the blade to remain on the saw until it is no longer sharp enough to cut, without gullet cracks developmg, dehvermg a service hfe to the blade that allows the blade to be used until sharpening renders the blade too narrow for use 2 The method of claim 1 where the means of dπvmg the bandsaw dπve wheel and the means of brakmg the saw facilitate acceleration and deceleration of the band wheels and bandsaw blade at a rate that will allow the blade to be accelerated up to operating speed m less than 2 5 seconds and stopped again the same time frame 3 The method of claim 2 where the band wheels are built sufficiently light to allow the power required for cuttmg to accelerate the blade up to cutting speed at the required rate 4 The method of claim 1 where die width of the bandsaw blade is measured from the back edge of the blade to the bottom of the gullet, and in the case of a double cut bandsaw blade the width should be measured between opposing gullets 5 The method of claim 1 where the means of dπving the bandsaw dπve wheel and the means of brakmg the bandsaw compπse an entire automotive dπve train including motor, clutch, gearbox, tail shaft, differential, axle, brake, hub and control means 6 The method of claim 5 where the automotive dπve tram remains in its chassis and the axle housing is removed from the oπgmal suspension and attached directly to the chassis 7 The method of claim 5 where the differential centre is locked or welded to permit all dπve force to be directed to one axle 8 The method of claim 5 where the gearbox can be shifted to neutral allowing the dπve to be disengaged so that the clutch may be released 9 The method of claim 5 where the control means includes means for controlling engine throttle, clutch, gearbox and brake 10 The method of claim 9 where the control means is controlled directly or remotely by the operator, or bv computer set works, and the clutch and brake, is controlled by one pedal and the same master cylinder 1 1 The method of claim 5 where the hub is attached to the bandsaw dπve shaft by means of a coupling capable absorbing some degree of misalignment 12 The method of claim 5 where the hub has the bandsaw wheel attached directly thereon 13 The method of claim 1 where the dπve means and brake means compπse an external power means, hydraulic pump, hydraulic motor, hydraulic control means and hydraulic tank 14 The method of claim 13 where the external power means is an electπc motor, an internal combustion engine or other form of continuous power supply 15 The method of claim 13 where the hydraulic control means is an hydraulic valve that is controlled directly or remotely by the operator, or by computer set works 16 The method of claim 15 where the hydrauhc control means directs hydraulic oil from the hydraulic pump to the hydrauhc motor for cutting 17 The method of claim 15 where the brake means is effected by the hydraulic control means to stop the saw 18 The method of claim 15 where the hydraulic control means directs hydraulic oil from the pump to the tank while not cuttmg 19 The method of claim 13 where the hydraulic motor is mounted directly on the band wheel dπve shaft 20 The method of claim 13 where the hydraulic motor dπves the band wheel dπve shaft via a gearbox or other reduction device 21 The method of claim 1 where the dπve means compπses an external power means, a clutch means, a brake means and a control means 22 The method of claim 21 where the external power means is an electπc motor an internal combustion engine or other form of contmuous power supply 23 The method of claim 21 where the clutch means and brake means are pneumatically, hydrauhcally or mechanically operated 24 The method of claim 21 where the control means is controlled directly or remotely by the operator, or by computer set works 25 The method of claim 1 where the strain means is able to apply a force exceedmg 2 x 230 x W x 0 00163 D Newtons. where W and D are respectively the width of the saw blade and the diameter of the band wheel 26 The method of claim 1 where the method of operation will still succeed when the ratio of bandsaw blade thickness to band wheel diameter is increased to 0 00163 and blade stram is set to σ t = 230 N ' mm" 27 The method of claim 1 where the means of reducmg bandsaw blade fatigue is aided by a gullet stress reduction strategy which involves reducmg stress concentrations in the gullet of the bandsaw blade by firstly ensuπng that the bottom of the blade gullet does not have a tight radius and is substantially flat and secondly that the bottom of the gullet has gπndmg marks removed either by reaming or some means of polishing 28 A bandsaw apparatus compπsmg (a) an automotive dπve tram mcludmg motor, clutch, gearbox, tail shaft, differential, axle, brake, hub and control means. (b) a dπve wheel and at least one dπven wheel, entrained over which is (c) a bandsaw blade of a width no less than 100 mm. (d) where the ratio of bandsaw blade thickness to band wheel diameter exceeds 0 0014, or (e) where future advances m steel toughness, allow bandsaws to run a thicker gauge blade for a given wheel diameter, increasing the conventional limit of blade thickness to band wheel diameter from 0 001 , then the ratio of blade thickness to band wheel diameter must exceed that new limit by 40 percent 29 The apparatus of claim 28 where the automotive dπve tram remains in its chassis and the axle housing is removed from the oπginal suspension and attached directly to the chassis 30 The apparatus of claim 28 where the differential centre is locked or welded to permit all dnve force to be directed to one axle 31 The apparatus of claim 28 where the gearbox can be shifted to neutral allowing the dπve to be disengaged so that the clutch may be released 32 The apparatus of claim 28 where the control means mcludes means for controlling engine throttle, clutch, gearbox and brake 33 The apparatus of claim 28 where the control means allows the clutch and brake to be controlled by the same master cylinder 34 The apparatus of claim 32 where the control means is controlled directly or remotely by the operator, or by computer set works 35 The apparatus of claim 28 where the hub is attached to the bandsaw dπve shaft by means of a coupling capable of absorbing some degree of misalignment 36 The apparatus of claim 28 where the hub has the bandsaw wheel attached directly thereon 37 A bandsaw apparatus compπsmg (a) an external power means, hydraulic pump, hydraulic motor, hydraulic control means and hydraulic tank. (b) a dπve wheel and at least one dπven wheel, entrained over which is (c) a bandsaw blade of a width no less than 100 mm, (d) where the ratio of bandsaw blade duckness to band wheel diameter exceeds 0 0014, or (e) where future advances in steel toughness, allow bandsaws to run a thicker gauge blade for a given wheel diameter, increasing the conventional limit of blade thickness to band wheel diameter from 0 001. then the ratio of blade thickness to band wheel diameter must exceed that new limit by 40 percent 38 The apparatus of claim 37 where the external power means may be an electπc motor, an internal combustion engine or other form of continuous power supply 39 The apparatus of claim 37 where the hydrauhc control means is an hydraulic valve that may be controlled directly or remotely by the operator, or by computer set works 40 The apparatus of claim 39 where the hydraulic control means directs hydraulic oil from the hydrauhc pump to the hydraulic motor for cutting 41 The apparatus of claim 39 where the brake means is effected by the hydraulic control means to stop the saw 42 The apparatus of claim 39 where the hydraulic control means directs hvdraulic oil from the pump to the tank while not cuttmg 43 The apparatus of claim 37 where the hvdraulic motor is mounted directlv on the band wheel dπve shaft 44 The apparatus of claim 37 where the hydraulic motor dπves the band wheel dπve shaft via a gearbox or other reduction system. 45 A bandsaw apparatus compπsmg (a) an external power means, a clutch means, a brake means and a control means, (b) an external power means, hydraulic pump, hydraulic motor, hydraulic control means and hydraulic tank, (c) a dπve wheel and at least one dπven wheel, entrained over which is. (d) a bandsaw blade of a width no less than 85 mm, (e) where the ratio of bandsaw blade thickness to band wheel diameter exceeds 0 0014, or if) where future advances in steel toughness, allow bandsaws to run a thicker gauge blade for a given heel diameter, increasing the conventional limit of blade thickness to band wheel diameter from 0 001. then the ratio of blade thickness to band wheel diameter must exceed that new limit by 40 percent 46 The apparatus of claim 45 where the external power means may be an electπc motor, an internal combustion engine or other form of continuous power supply 47 The apparatus of claim 45 where the clutch means and brake means may be pneumatically, hydraulically or mechanically operated 48 The apparatus of claim 45 where the control means mav be controlled directlv or remotely by the operator, or by computer set works AMENDED CLAIMS [received by the International Bureau on 19 September 2000 (19.09.00); original claims 1-48 replaced by new claims 1-54 (4 pages)] The claims defining the invention are as foilαwε: 1. A method of operation of a bandsaw of the type comprising a drive wheel and at least one driven wheel, entrained over which is 5 a bandsaw blade of a width no less than 85mm, where the ratio of bandsaw blade thickness to the diameter of the largest band wheel exceeds the conventional limit by 35% or more, a means of applying strain to the bandsaw Made, a means of driving the bandsaw drive wheel and 10 a means of braking the bandsaw, including the steps of (a) positioning the log or timber tor cutting, which may include moving the bandsaw, (b) engaging the drive mean.- to spin the bandsaw υp to operating is speed, (c) effecting a cut through the timber, (d) using the means of braking to stop or slow the bandsaw, and (e epositionlng the bandsaw or log orttmber to effect the next cut. or positioning the next log or timber, which may Include moving the 20 bandsaw. 2. The method of claim 1 where the means of driving the bandsaw drive wheel and the means of braking the saw facilitate acceleration and deceleration of the band wheels and bandsaw blade at a rate that wβl aHow zs the blade to be accelerated up to operøtirtg speed in less than 2.5 seconds and stopped again In the same time frame. 3. The method of claim 2 where the band wheels am butt sufMeπtly Hght to allow the power required for cutting to accelerate the blade up to cutting speed at the required rate. 30 4. The method of dalπ. 1 where the width of the bandsaw Made te measured from the beck edge of the blade to the bottom of the guBβt, and in the case of a double out bandsaw blade the width should be measured between opposing guUets. 5. The method of claim 1 where the means of driving the bandsawdrive 35 wheel and the means of braking the bandsaw comprise an entire automotive drive train including motor, clutch, gearbox, tall shaft, differential, axle, brake, hub and control means. 6. The method of claim 5 where the automotive drive train remains in its chassis and the axle housing Is removed from the original suspension and 40 attached directly to the chassis. 7. The methCKi of cteim 6 vΛere me dlfferenta! centre to permit ail drive force to be directed to one axle. 8. The method of claim 5 where the gearbox can be shitted to neutral allowing the drive to be disengaged so that the dutch may be released. 4$ 9. The method of dalm 5 where the control means Includes means for controlling engine -throttle, dutch, gearbox and brake. 10. The πnethod of daim 9 where trβ control means is coπtroflod remotely by the operator, or by computer set works, and the dutch and brake, Is controlled by one pedal and the same master cylinder. 11. The method of daim 5 where the hub is attached to the bandsaw drive 5 shaft by means of a coupling capable absorbing some degree of misalignment 12. The method of daim 5 where the hub has the bandsaw wheel attached directly thereon. 13. The method of claim 1 where the drive mean - and brake means 10 comprise an external power means, hydraulic pump, hydraulic motor, hydraulic control means and hydraulic tank. 14. The method of daim 13 where the external power means is an electric motor, an Internal combustion engine or other form of continuous power supply. is 15. The method σf daim 13 where the hydraulic control means is an hydraulic valve that is controlled directly or remotely by the operator, or by computer set works. 16. The method of daim 16 where the hydraulic control means directs hydraulic oil from the hydraulic pump to the hydraulic motor for cutting. 20 17. The method of daim 1δ where the brake means is effected by the hydraulic control means to stop the saw. 18. The method of dalm 15 where the hydraulic control means directs hydraulic oil from Hie pump to the tank while not cutting. 19. The method erf dabn 13 where the hydraulic motor is mounted directly 23 on the band wheel drive shaft 20. The method of dalm 13 where the hydraulic motor drives the band wheel drive shaft via a gearbox or other reduction device. 21. The method of daim l where the drive means comprises an external power means, a clutch means, a brake means and a control means. 30 22. The method σf claim 21 where the external power means is an electric motor, an internal combustion engine or other form of continuous power supply. 23. The method of daim 21 where the clutch means and brake means are pneumatically, hydraulically or mechanically operated. JS 24. The method of dalm 21 where the control means is controlled directly or remotely by the operator, or by computer set works. 25. The method of claim 1 where the strain means is able to apply a force exceeding 2 x 230 x W x 0.00163 D Newtons, where W and D are respectively the width of the saw blade and the diameter of the band wheel. 40 26. The method of daim 1 where the method of operation wit still succeed when the ratio of bandsaw blade thickness to band wheel cϋarπetBr Is increased to 0-00163 and blade strain is set to σ. - 230 N / mm 2 . 27. The method or daim 1 where the means of reducing bandsaw Made fatigue is aided by a guHei stress reduction strategy which involves redudng stress concentrations In the gullet of the bandsaw blade by flrsdy ensuring that the bottom of the blade gullet does not have a tight radius and is substantially 5 flat and secondly that the bottom of the gullet has grinding marks removed either by reaming or some means of polishing. 28. A method of any one of daim-. 1 to 27 wherein said timber is arranged for cutting by more than one said bandsaw. the method of operation including the step of: 10 (a) repositioning the bandsaws relative to each other between cuts. 29. A bandsaw apparatus comprising (a) drive and control means for respectively driving and controlling rotation of a bandsaw drive wheel, (b) a drive wheel and at least one driven wheel, entrained over which is 15 (c) a bandsaw blade of a width no less than 85 mm, (d)where the ratio of bandsaw blade thickness to band wheel diameter exceeds the conventional limit by 35% or more. 30. The bandsaw apparatus of daim 29 wherein the drive means Indudes: (a) extern--, power means, and 20 (b) transfer means for transferal of power from the external power means to the bandsaw drive wheel. 31. The apparatus of daim 30, wherein the external power means and transfer means respectively indude: (a) a motor, and 25 (b) an automotive drive train including the motor, clutch, gearbox, tail shaft, differential, hub and axle. 32. The apparatus of daim 31, wherein the control means may include means for controlling one or more of the following: a throttle of the motor, the dutch, gearbox and brake. 30 33. The apparatus of dalm 32, wherein the control means further indudes external power means, a hydraulic pump and hydraulic motor, hydraulic control means and a hydraulic tank. 34. The apparatus of daim 30, wherein the transfer means Indudes a hydraulic motor, hydraulic pump and hydraulic tank. 35 35. The apparatus of daim 34, wherein the control means indudes hydraulic control means. 36. The apparatus of any one of daims 29 to 35, wherein the Handsaw blade which is entrained over the drive wheel and at least one driven wheel is of a width no less than 85mm. 40 37. The apparatus of any one of daims 29 to 36, wherein the ratio αf bandsaw blade thickness to band wheel diameter exceeds the convention limit by 40% or more. 38. The apparatus αf daim 31 where the automotfve drive train remains in its chassis and the axle housing is removed from the original suspension and 4. attached directly to the chassis. 39. The awJ β ra-t-B θf arτyor« c3f damτ331 to 33 wherethθ drf Brer«al centre is locked or welded to permit all drive force to be directed to one axle. 40. The apparatus of any one of claims 31 to 33 where the gearbox can be shifted to neutral allowing the drive to be disengaged so that the dutch may be released. 41 The apparatus of claim 32 or daim 33 where the control means allows the dutch and brake to be controlled by the same master cylinder. 42. The apparatus of any one of daims 29 to 41 where the control means is controlled directly or remotely by the operator, or by computer set works. 10 43. The apparatus of any one of daims 31 to 33 where the hub is attached to the bandsaw drive shaft by means of a coupling capable absorbing some degree of misalignment. 44. The apparatus of any one of daima 31 to 33 where the hub has the bandsaw wheel attached directly thereon. is 45. The apparatus of any one of claims 30 to 44 where the external power means may be an electric motor, an internal combustion engine or other form of continuous power supply. 46. The apparatus of any one of claims 33, 35 to 37 where the hydraulic control means Is an hydraulic valve that may be ooπtroled directly or remotely 20 by the operator, or by computer set works. 47. The apparatus of any one of daims 33, 35 to 37 where the hydraulic control means directs hydraulic oil from the hydraulic pump to the hydraulic motor for cutting, 48. The apparatus of claim 33 where the means for controlling the brake Is 25 effected by the hydraulic control means to stop the saw. 49. The appara*u5 θf --nyone σfdaims 33, 35 to 37 wnemthe hydraι*c control means directs hydraulic oD from the pump to the tank white not cutting. 50. The apparatus of dalm 33 or daim 34 where the hydraulic motor is mounted directly on the band wheel drive shaft 30 51. The apparatus of dalm 33 or claim 34 where the hydraulic motor drives the band wheel drive shaft via a gearbox or other reduction system. 52. The apparatus of any one of claims 30 to 37 where the external power means may be an electric motor, an internal combustion engine or other form of continuous power Supply. 35 53. The apparatus of daim 32 or daim 33 where the means for controlling the dutch or brake may be pneumatically, hydraulrcally or mechanically operated. j>4. The apparatus of any one of daims 29 to 53 where the control means may be controlled directly or remotely by the operator, or by computer set works. Alexander David Douglas 20 May 2000

Inventors: DOUGLAS ALEXANDER DAVID, DOUGLAS, ALEXANDER, DAVID
Applicants: DOUGLAS ALEXANDER DAVID, DOUGLAS, ALEXANDER, DAVID
Application year: 2000
Main classification: B27B13
IPC codes: B23D55