US2726691A - Debarking machine having underlying bark-stripping helical rollers and an overlying adjustable pressure roller - Google Patents

Description

2,726,691 Dec- 3. 1955 P. HARWOOD ET AL DEBARKING MACHINE HAVING UNDERLYING BARK-STRIPPING HELICAL ROLLERS AND AN OVERLYING ADJUSTABLE PRESSURE ROLLER Filed Sept. 7, 1954 5 Sheets-Sheet l Altarney 2 726 691 Dec. 13. 1955 P. HARWOOD E! AL DEBARKING MACHINE HAVING UNDERLYING BARK-STRIPPING HELICAL ROLLERS AND AN OVERLYING ADJUSTABLE PRESSURE ROLLER Filed Sept. 7, 1954 3 Sheets-Sheet 2 F/GZ.

Inventor; GOR 0077 a fl gfia s 792L041. BAA-m $544740? Attorney- United tates Patent O 2,726,691 DEBARKING HAVING UNljERLYiNG BARK-STRIPPING HELICALROLLERS AND AN OVERLYING ADJUSTABLE PRESSURE ROLLER Philip Harwood, Little Sutton, Wirral, and Gordon Bohert Jacob, Queens Park, Chester, England, assigiors to J. R. Gordon & Co. Limited, Cardiif, Wales, a British company Application September 7', 1954*, Serial N0. 454,424

Claims priority, application Great Britain September 9, 1953 8 lairns. (Cl. lid-2&3}

This invention concerns debarking machines and more especially relates to such machines which are suitable for the treatment of relatively short lengths of round timber.

In most known types of debarkingapparatus the log is held whilst one or moreblades or the like rotate around the log and progressively move along it, or the blades rotate around it whilst it is moved along axially with respect to the center of rotationof the blade or blades. This arrangement is adopted because of the great lengths of timber which these machines normally have to accommodate, and consequently they are normally of large and robust construction, require a considerable amount of adjustment and maintenance, and are usually permanently accommodated Within a building, for instance, a saw-mill.

An object of the present invention is to provide a debarking apparatus of relatively small dimensions, and of simple and robust construction, which is capable of being readily transported from place to place, and which may be set up and operated in situ where the timber is felled or any other convenient place.

Another object of the present invention is to provide a machine which will remove bark and bast in one opera-' tionwithout damage or loss of wood, and which can handle rough or scrub timber which may contain large numbers of knots and be irregular in shape. The machine does not have knives or cutters such as are provided in some earlier constructions, and is therefore very robust and able to stand up to heavy duty and racking conditions. 7

According to the present invention'a debarking machine comprises rotating stripping means and a pressure-exerting member, said stripping means being adapted to convey the timber being stripped through the machineand said pressure-exerting member beingarranged to hold the timber against the" rotating stripping means and control the feeding speed.

Preferably the stripping means comprise a pair of short debarking rollers spaced apart and mounted longitudinally in the direction of travel of the wood therethrough with their axes parallel. These rollers, which are each driven in the same direction, may carry helical projections, for instance in the form of a worm thread or a scroll, which projections effect the stripping of the timber. These helical projections are of similar pitch and each preferably has a short taper at the input end. The term taper implies that the external" diameter of the projection and the root diameter of the core upon which the projection is carried are progressively reduced at one end of each debarking roller. For example, a section having a taper angle of about 30 may be provided'at one end of each debarking roller which then has 'a central'c'ylindrical length carrying the projection and thereafter terminates in a solid cylindrical end portion of diameter equal to that of the maximum external diameter of the projection.

The pressure-exerting member may be constituted by a roller, mounted above the debarkingr'ollers for rota- Tee 2' tion in the same direction as the debarking rollers but at a slower speed about an adjustable axis.

This adjustability enables the pressure roller to beset with the pressure-roller axis at various angles relative to the axes of the debarking rollers for the purpose of varying the speed of progression of logs passing through the machine. I v

The invention will now be further described byway of example with reference to the accompanying drawings in which: X I

Fig. 1 is a general side perspective view of a preferred embodiment of a debarking machine according to the invention in the formof a two-wheeled vehicle trailer;

Fig. 2 is a diagrammatic'view from the opposite side of the machine basically illustrating the invention with certain parts displaced from the position they normally occupy or shown toadifierent scale for the sake of clarity;

Fig. 3 is a. fragmentary perspective view of the operating section of thema'c hine; V V A Pg. 4 is a perspective view similar to Fig. 3 but to an enlarged scale, certain parts being omitted; and

Fig. 5 is a fragmentary perspective detail of part of the operating'head'. v V r v j I The preferred debarking machine illustrated includes a main framework generally indicated by it), constituting part of a two-wheeled trailer provided with suitable means. 11 for attachment to a vehicle. The trailer is provided with adjustable supports or legs 12 at each corner in known manner these supports being lowered (asv shown in Fig. I) when the debarking machine is in use and lifted (as shown in Fig. 2 when the machine is being transported. As each support is adjustable independently, the machine can be made rigid and stable irrespective of the state of the grouncl'on' which it may stand.

Mounted on the framework 10 are two sets of bearings 13a, 13b and Mn, 14b, for the rotating. stripping. means constitiittedby rollers 15 and' 16. These rollers carry helical projections ISajand 16d, Which projections are of similar pitch" but which gradually increase in radius from the infeed end towardtheoutfee'd end, as can be seen from Fig. 4. v The rollers 15am to are driven in the same direction (anticlockwise as viewed in Fig. 2.) by sprockets 17 and 13 mounted onthe' roller shafts and chains 19 and 2%, which in turn engage witha double sprocket 21 carried by a secondary countershaft 22. Each of the rollers 15 and 16,- and its associated helical projections 15a and 16a is tapered at the input end so that, as shown in the regions I51) and 11671 (Fig. 4), the external diameter of each projection and the root diameter of the cores upon Which the projections are carried are progressively reduced at one end of each roller. At the output end the rollers IS'and 1 5 terminate ina solid cylindrical end portion and 166, equal in diameter to that of the maximum external diameter of the "projections. The portions 150 and 16c tend to exert a braking and polishing action on'the debarkedtimber as it'p'asses through the machine in the direction of the arrow'Ain'Fig. 3. j

It will bea'pp'reci'ated' that any timber introduced onto the rotating-debarking rollers 15, 16 without any other co-opera-ting members'b'eiiig provided, would simply result in a rapid conveying of the timber through the machine without any stripping thereof taking place. To prevent this a pressure element is? provided to force the timber against the" debarking rollers 15, 16 and ensurev that the wood rotates at a speed slower than the debarking rollers,

so that they do in fact strip the'bark and bast from the timber. I V

In the embodiment illustrated, the pressure-exerting member is constituted by a roller 23, of greater diameter than the debarking 'rollers, rotatably mounted above rollers 15, 16 in bearings 2512,2413 carried by aplatforrn 25 at one eiid of'anarm miz', thefother end of which arm is pivposition are provided (see Fig.'5)., These means comprise a bolt 27, mounted rigidly on arm a by a system.

of lock nuts and depending through aslot 25b in platform 25. 'Beneaththisplatform, bolt 27 carries-a sleeve 28 threadedly engaged therewith, which sleeve has a lever 28a attached thereto and also has a flange on its upper surface adapted to bear against the underside of platform 25; Movement of lever 28a can thereby lock or unlock platform 25 and its associated parts relative tothe arm 10a. By moving lever 28a to its unlocked position, the platform 25 and roller 23v can be adjusted about point 26 within the limits-of slot 25b until the desired orientation of roller 23 with respect torollers and'16 is obtained, and then the pressure head can be locked in that position by lever 28a. Handle 25a is provided to facilitate adjustment, so that it is possible to vary the speed of progression of timber passing through the machine.

Pressure roller 23 is naturally urged towards debarking rollers 15 and 16 by gravity due to its own weight, and that of arrnltla and associated parts. This is supplemented however by spring force provided by heavy-duty springs 29 arranged between arm 10a and lever 30 pivoted at one end at 30a to an upright of the main framework. The other end of lever 30 carries a hand grip so that the machine operator can engage the lever in any one of a number of notches provided in a plate 31 fastened to another upright of the main framework, and by this means adjust the spring force that urges pressure roller 23 downwards.

The movement of roller 23 and arm 10a in an upward direction is effected by an effort applied by the operator. A steel rope 32 attached to a lug on the arm 10a passes over pulleys mounted in'the top of the machine and is connected to a hand lever 33, whilst a further steel rope 34 may connect hand lever 33 to a foot pedal 35. In this waythe. lifting of the pressure roller 23 can be effected by a combined hand-and-foot action. An adjustable stop member 36 is provided to limit the amount of downward movement of the pressure roller 23 by control of the upward movement of foot pedal 35. Stop 36 can also .be used to retain pressure roller 23 in a retracted (upward) position, by fixing the foot lever in its lowermost position, in the event that it is necessary for the operator tothave access to rollers 15, 16 for the purpose of cleaning, renewing or the like.

The pressure roller 23 is formed with rubber end portions 23a and a toothed central metal portion 23b. It is driven at a slower speed than roller 15, 16 by an overhead shaft 37 carried on bearings in arm 10a and is provided with suitable couplings, such as universal couplings 62, to allow the adjustment of the pressure head previously described. Reduction gear 38 transmits the rotation of shaft 37 to sprocket 39, which drives sprocket 40 on shaft 41 of roller 23 through chain 42. Shaft 37 receives its drive through a pulley 43 mounted thereon, a belt 44 and a pulley 45 carried by a primary countershaft 46. A dou- 'ble pulley 47 also carried by countershaft 46 is connected by belt 48 to pulley 49 on secondary countershaft 22 to drive the latter, and is also connected by belt 50 to the driving pulley 51 of a prime mover 52 for the machine. In this manner a common power unit such as a diesel or petrol engine, serves to drive both debarking rollers and the pressure roller.

In operation, the pressure roller 23 is adjusted and fixed so that its axis of rotation is such that it will have 'a conveying or feeding action on the timber when brought type of timber being treated. Due to the'surface of roller 23 gripping the wood, they both rotate at the same speed. The debarking rollers are rotating much faster and effect a stripping of the bark and bast from the timber. The'amount of stripping can be controlled by adjust ment of pressure by lever 30. The timber leaves the machine at C (Fig. 3). s 1

A limit stop maybe provided totprevent downward dis 7 placement of the arm 10a and associated parts so as to avoid the pressure roller coming into contact with the de-.

barking rollers in the event of breakage of rope 32. This stop is conveniently constituted by a rod 53 pivotally a tube 54 pivotally mounted on the main framework 10. If rope 32 breaks, arm 10a will fall, but before roller 23 comes into contact with debarking rollers.15, 16 rod 53 abuts against a solid portion 54a of'tube 54, so that further downward movement is prevented. If 'desired, holes (not shown) bored through rod 53 and tube 54 may be used together with a co-operating pin to prevent movement of arm 10a and its associated parts during transportation.

An impeller 55 is arranged below the debarking rollers 15, 16, on secondary countershaft 22 (Figs. 2 and 3) for the purpose of disposing of bark fragments which drop down during the debarking process, and which are shot out against a shield 56 arranged behind the rollers. The

impeller is arranged to deliver the bark fragments through a duct 57 so that they may be readily collected at one end of the machine. Arrows indicate the path of the stripped bark.

A lead-in or guide trough 58 hinged and locked around the debarking rollers is provided to protect the operator.

from the moving parts and to prevent logsof unusual or irregular shape from breaking loose or becoming ejected. prematurely. The trough may beat least partly composed of rubber, so that its shape is readily adapted toirregular timber. may be provided and if this is a flexible member it will accommodate timber of awkward or unusual shape. Such a support may be in the form of a chain 59 arranged between small upright stanchions 60 on the main framework 10.

Preferably arm 10a is guided in its vertical movement by rollers 61 mounted thereon and bearing against uprights of the main framework 10. 7

Suitable guards 63 are arranged over chain and other drives in normal manner.

Conveniently a roof 64 is arranged over the machine,

and canvas side and end pieces 65 may be provided for" lowering into position during transportation.

As stated the machine is particularly suitable for small lengths of round timber. It, is quite common for the latter to have a considerable number of knots and other irregularities near the surfaceand such hard pieces of wood would tend to override the stripping projections and simply lift the timber slightly in the machine and push the pressure roller 23 upwards against the force exerted by its weight and the springs. To overcome this, breakers, 15d, 16d are introduced at spaced intervals between the convolutions of each projection 15a, 16a; These breakers 15d, 16d comprise narrow bars staggered with respect to one another (Fig. 4) and may have a strengthened and sharpened leading edge, so that any knots or the like which they encounter are cut or broken from the timber.

The smallness and compactness of the machine makes it readily transportable, and as stated although it is designed for debarking short lengthsof timber such as from one widelyvarying top diameters.

As the pressure applied to the timber is readily variable A further'support for long lengths of timber' of wood removed on the passage of the logs through the machine. Furthermore, it is possible to deal with batches of timber of mixed types, species and conditions, and sorting before debarking is not necessary.

With the machine illustrated, it is possible to debark about 150 cubic feet of timber of an average of four to five inches diameter per hour. A suitable speed for the debarking rollers 15, 16 is about 750 revolutions per minute, in which case the pressure roller 23 may be driven at a speed of about 30 revolutions per minute.

We claim:

1. A debarking machine for timber comprising rotating stripping means formed by a pair of debarking rollers carrying helical projections for effecting the debarking of timber, and a pressure-exerting member constituted by a roller mounted above said debarking rollers for rotation about an adjustable axis, said debarking rollers each being driven in the same direction as, but at a greater speed of rotation than, that of said pressure-exerting roller and being adapted to convey timber being stripped through the machine, and said pressure-exerting roller being arranged to hold said timber against said helical projections and control the speed at which said timber is conveyed through the machine.

2. A debarking machine for timber comprising rotating stripping means formed by a pair of debarking rollers each having a tapered end portion, a central portion and a solid cylindrical end portion, and a pressure-exerting member, said tapered and central portions of each of said debarking rollers having helical projections, said debarking rollers each being driven in the same direction and being adapted to convey timber being stripped through the machine from said tapered end portions, and said pressure-exerting member being arranged to hold said timber against said debarking rollers and control the speed at which said timber is fed through the machine.

3. A debarking machine for timber comprising rotating tripping means formed by a pair of debarking rollers carrying helical projections for efiecting the debarking of timber, and a pressure-exerting member, said debarking rollers having breaker bars fitted at spaced intervals between convolutions of said helical projections, being driven in the same direction of rotation and being adapted to convey timber being stripped through the machine, and said pressure-exerting member being arranged to hold said timber against said helical projections and control the speed at which said timber is fed through the machine.

4. A debarking machine for timber comprising rotating stripping means formed by a pair of debarking rollers, and a pressure-exerting member constituted by a roller mounted above said debarking rollers for rotation about an adjustable axis, said debarking rollers each being driven in the same direction at a greater speed of rotation than that of said pressure-exerting roller and being adapted to convey timber being stripped through the machine, and said pressure-exerting member having rubber end portions and a toothed, central, metal portion whereby to hold said timber against said debarking rollers and control the speed at which said timber is fed through the machine.

5. A debarking machine for logs comprising a prime mover, a pressure-exerting roller driven by said prime mover, and debarking means consisting of a pair of debarking rollers also driven by said prime mover in the same direction as but at a much greater speed than said pressure-exerting roller, each of said debarking rollers having a helical projection and breaker bars arranged between the convolutions of said projections parallel to the axes of said rollers, said debarking rollers effecting a stripping of logs which are conveyed through the machine at a speed controlled by said pressure-exerting roller.

6. A debarking machine for logs comprising a prime mover, a pressure-exerting roller driven by said prime mover, and debarking means consisting of a pair of debarking rollers also driven by said prime mover in the same direction as but at a much greater speed than said pressure-exerting roller, each of said debarking rollers having a helical projection, each of said projections being of uniform diameter over a portion of its length and then tapering towards the infeed end, said debarking rollers effecting a stripping of logs which are conveyed through the machine at a speed controlled by said pressure-exerting roller.

7. A debarking machine for logs comprising a prime mover, a pressure-exerting roller driven by said prime mover and debarking means consisting of a pair of debarking rollers also driven by said prime mover in the same direction as but at a much greater speed than said pressure-exerting roller, each of said debarking rollers having a helical projection of similar pitch, said projections being of uniform diameter over a portion of their length and then tapering towards the infeed end, each debarking roller having a solid cylindrical portion at the outfeed end of equal diameter to the projection, said projections efiecting a stripping of the logs which are conveyed through the machine at a speed controlled by the pressure-exerting roller.

8. A debarking machine for logs comprising rotating stripping means formed by a pair of debarking rollers member, said tapered and central portions of each of said mounted above said debarking rollers for rotation about an adjustable axis, said pressure-exerting roller having rubber end portions and a toothed central portion, said debarking rollers being driven in the same direction at a greater speed of rotation than that of said pressure-exerting roller and being adapted to convey the logs through the machine, said pressure-exerting roller being arranged to hold said logs against said debarking rollers and control the speed at which said logs are fed through the machine.

References (Iited in the file of this patent UNITED STATES PATENTS 1,300,748 Lombard Apr. 15, 1919 2,015,936 Hokonson Oct. 1, 1935 2,390,459 Power Dec. 4, 1945 2,669,266 Bouchard Feb. 16, 1954

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