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
  • B27B31/00—Arrangements for conveying, loading, turning, adjusting, or discharging the log or timber, specially designed for saw mills or sawing machines
  • B27B31/006—Arrangements for conveying, loading, turning, adjusting, or discharging the log or timber, specially designed for saw mills or sawing machines with chains or belts

Definitions

• the present invention relates to plant for feeding timber boards to and through a single-board feeder in accordance with the preamble of Claim 1.
• the invention relates in particular to high-speed production plants, i.e. plants in which the boards are fed to different stations at high speeds.
• the timber boards are normally transported in sawmills with their longitudinal axes transversal to the direction of conveyor belt movement.
• the boards are not distributed uniformly on the belts and the spacings between the boards can vary widely.
• the boards are advanced with the aid of so-called single-board feeders which grip boards stored temporarily in a buffer region and advance the boards one by one for further handling.
• the general aim is to increase the rate of production and therewith the speed at which boards are transported through the plant, it is endeavoured to keep the buffer region upstream of the individual board feeder under control, so that the buffer region will neither be too large nor too small.
• An excessively large buffer region will result in various kinds of disturbances in operation. For instance, the boards will not remain in contact with the conveyor, but will be pressed up and lifted in the buffer region. If the buffer region is too small or when no boards are present in said region, the feeder will stop. Both instances will immediately result in an interruption in production. Because a high production rate is contingent on the continuous outfeed of boards downstream of the board feeder, the buffer region must be kept constantly full of boards above a given lowest level, wherein the feeder output rate V ut , i.e.
• the number of boards that are fed out per unit of time multiplied by the width of the board must be lower than the board feeding speed V ⁇ n upstream of the individual board feeder.
• the buffer region upstream of the board feeder can be said to form a magazine or storage facility and is thus necessary for single-board feeding.
• the invention also enables boards of different widths and thicknesses carried on the conveyor belt to be dispensed effectively and positively, and also enables two or more boards to be dispensed at one and the same time.
• Dispensers constructed to this end are known to the art, and reference is made in this regard to Swedish Patent Specifica ⁇ tion 7700760-7 which teaches a dispensing device for dispens ⁇ ing timber boards of different widths and thicknesses or heights. Reference is also made to Swedish Patent Application 9403668-8 which teaches a device for dispensing two timber boards at one and the same time. However, this so-called board dispensing function still constitutes a "bottleneck" that limits production rates and therewith the capacity of other plant equipment. Although it is possible to enhance the capacity by double-feeding as proposed in Swedish Patent Application 9403668-8, double-feeding is required only with regard to a part of the sawmill production line. These known devices and arrangements, however, have been found wanting when required to dispense boards of mixed dimensions and when requiring alternating double-feeding and single-feeding of the boards. For instance, these devices must be attended constantly by experienced operators and do not provide the high capacity desired.
• Fig. 1 is a schematic side view of a conveyor path on which timber boards are placed cross-wise in the vicinity of a single- board feeder
• Fig. 2 is a schematic side view of an inventive board dispensing device
• Fig. 3 illustrates the device of Fig. 2 with a board gripped for transportation away from a timber board buffer facility
• Fig. 4 illustrates the device subsequent to the board having been "spat away" from the board buffer facility
• Fig. 5 illustrates a somewhat different embodiment of the device illustrated schematically in Fig. 2.
• the conveyor belt of the embodiment illustrated in Fig. 1 has the form of a belt conveyor 1 whose board-feeding rate is referenced V in .
• the reference numeral 2 identifies a single- board feeder whose board-feeding rate is referenced V ut and which will be described later on.
• the conveyor 1 moves the boards 4 at the speed V ⁇ n , said boards lying cross-wise to th ⁇ ' conveying direction.
• the boards 4 will not normally be distributed regularly on the conveyor 1, but may be spaced unevenly therealong. This is indicated on the left of the Figure.
• the single-board feeder 2 Since the single-board feeder 2 is intended to feed the boards one by one on a forwarding conveyor provided with dogging means, as indicated on the right of the Figure, it is necessary to obtain a given temporary storage or buffer 3 upstream of the single-board feeder. This buffer is obtained by ensuring that V ⁇ n is greater than V ut , as earlier indicated.
• the aforedescribed forms part of the known technology and a more detailed description is thereof unnecessary.
• the invention enables the buffer region 3 upstream of the single-board feeder 2 to be maintained within a controlled size.
• a regulator which includes endless belts 5 disposed across the width of the conveyor 1, each of said belts being guided over respective guide wheels or rollers 6, of which one is driven.
• the upper run of the endless belt 5 is located above the upper transporting plane of the conveyor 1 and will thus engage the timber boards 4.
• the upper run of the belt 5 shall move in the transporting direction of the conveyor 1.
• the speed of the belt 5 is V reg , which is lower than the speed V ln of the conveyor 1.
• the unevenly distributed boards 4 transported on the conveyor 1 will either be gripped or retarded by the belt 5 as a result of the difference between the speeds v ⁇ n and V. eg .
• a pre- buffer 3' will be built-up with boards on the upper run of the belt 5 at the same time as the regulator device will deliver the boards that collect thereon in a delayed rate ? to the conveyor 1 upstream of the single-board feeder 2 when so required by the feeder buffer 3.
• the pre-buffer 3' can be allowed to grow or expand to a given extent upstream of the regulator.
• feeder 2 will be equalized in accordance with the timing of the conveyor 1, i.e. an enlargement which keeps within largest and smallest permitted limits. Retardation of the boards and feeding of the boards to the single-board feeder 2 is made possible by utilizing the gaps between the boards on the conveyor 1 upstream of the regulator device.
• the invention thus enables building-up of the pre-buffer 3' and of the buffer 3 upstream of the single-board feeder 2 to be continued for given shorter periods, even if the feeder 2 is stopped due to a halt in production of the feeder, for instance.
• the regulator can be constructed to adapt to different speeds of the conveyor 1, and also to different board dimensions and feeder capacities.
• the regulator speed V reg will normally lie between V ⁇ n and V ut .
• the invention thus provides a highly flexible arrangement which can be installed in existing plants to solve an existing serious problem, particularly in the case of high-production plants.
• the conveyor belts may be of any appropriate kind and made from any suitable material, including high friction chains, provided that they will lower the rate of feed of the boards the speed V reg .
• a first belt conveyor or chain conveyor is refer- enced 400 and, when seen in the feed direction, includes a rear belt guide wheel 500 and a belt guide wheel 600 which is larger than the rear guide wheel 500.
• a conveyor belt runs around the guide wheels so as to provide lower and upper belt runs 700.
• the upper belt run 700 of the conveyor 400 runs in generally the same plane as the conveyor path 1 and a downstream conveyor path 800.
• the conveyor path 800 includes suitably spaced dogging means 900 and runs over a guide wheel 1000.
• the upper run of the dogging conveyor path 18 moves in the arrowed direction.
• a second belt or chain conveyor 1100 Mounted above the first belt or chain conveyor 400 is a second belt or chain conveyor 1100, which runs over a rear wheel 1200 and a wheel 1300 which is larger than the wheel 1200.
• the lower run 1400 of the second conveyor belt moves above the upper run of the first conveyor belt 400, with the belt guide wheel 1200 located essentially above the belt guide wheel 500 of the first conveyor.
• the two belt or chain conveyors 400 and 1100 together form a separate unit which, in the illustrated embodiment, can swing about the shafts 1500 and 1600 of respective wheels 600 and 1300.
• the arrangement includes a pneumatic or hydraulic piston-cylinder device 1700 and a link system 1800 by means of which the first conveyor 1400 can be swung about the shaft 1500, i.e.
• the second conveyor 1100 can be swung correspondingly about the shaft 1600, with the aid of a link system 1900 that is driven by a pneumatic or hydraulic piston-cylinder device 2000.
• the link system 1900 also includes a gas spring means 2100.
• the arrangement includes a sensor means 2200, for instance a light cell.
• the conveyor paths 1 and 800 work continuously when the arrangement is in operation, and the conveyors 400 and 1100 are driven continuously at a speed which is substantially greater than the speed of the conveyor path 1.
• the sensor means 2200 detects the presence of a board (Fig. 2)
• the first conveyor 400 is swung up about the shaft 1500, so as to lift the board.
• the second conveyor 1100 is rotated about the shaft 1600 so as to lower the lower belt run 1400 with the wheel 1200.
• the conveyor 1100 is, at the same time, lowered so that the board will be clamped between the two conveyors 400 and 1100 and their respective guide wheels 500 and 1200 (Fig. 3).
• the board clamped between the conveyors will be "spat out” over the conveyor 800 provided with said dogging means (Fig. 4) and dispensed through the medium of said dogging means by said conveyor.
• the timber boards will be "spat away” in a controlled and damped fashion, through the gap formed between the conveyors.
• the conveyor paths 1 and 800 are comprised of conveyor chains and that the conveyor path 1 is guided around wheels that are coaxial with the illustrated guide wheel 1000 of the conveyor path 800.
• the arrangement includes a plurality of belt or chain conveyors 400 and 1100 respectively between the conveyor chains of the conveyor paths 1 and 800 in the width direction of said paths.
• These conveyors 400 and 1100 may be five in number, as can also the stop means 300.
• dogging means 900 is shown in the drawings, it will be understood that dogging means are provided on the conveyor path 800 with a determined spacing, or pitch, therebetween.
• the first conveyor 400 is lowered and the second conveyor 1100 raised so that the arrangement will return to the starting position shown in Fig. 2. This procedure is repeated and if it is the board shown to the right in Fig. 2 that is to be dispensed, the second conveyor
• the piston-cylinder device 2000 can be regulated so as to enable the second conveyor 1100 to be adjusted with the guide wheel 1200 located above the top edge of the stop shoulder 300 at a height which corresponds to or slightly less than the height or thickness of the boards to be dispensed. Deviations in the height of the boards are taken up by the air springs 2100 also in this case.
• the stop shoulder 300 can be moved to a forward position 300' in the feed direction, so as to enable two boards to be dispensed from the buffer zone 3. When the stop shoulder is located in position 300', two boards will be fed forwards in the region above the upper run 700 of the belt conveyor 400.
• An alternative to the provision of a movable stop shoulder 300 is to provide two stop shoulders 300, 300' that can be lowered or swung out of the transportation plane.
• the stop shoulder 300' is moved out of the feed plane when feeding one board at a time, while the stop shoulder 300 is moved out of said feed plane when feeding two boards at a time. This also takes place automatically, of course.
• the second belt conveyor or chain conveyor 1100 is shown swung to a relatively high position in broken lines 2300. This indicates the possibility of opening the "gap" between the two conveyors 400 and 1100 so as to provide ready access to this region for taking any steps or measures that need to be taken.

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Wood Science & Technology (AREA)
• Forests & Forestry (AREA)
• Attitude Control For Articles On Conveyors (AREA)
• Interface Circuits In Exchanges (AREA)
• Paper (AREA)
• Feeding Of Articles To Conveyors (AREA)

Applications Claiming Priority (5)

Publications (2)

Family

ID=26662581

Family Applications (1)

Country Status (5)

Families Citing this family (4)

Family Cites Families (3)

• 1997
  • 1997-03-25 WO PCT/SE1997/000514 patent/WO1997038929A1/en active IP Right Grant
  • 1997-03-25 AU AU24160/97A patent/AU2416097A/en not_active Abandoned
  • 1997-03-25 EP EP97919812A patent/EP0929484B1/de not_active Expired - Lifetime
  • 1997-03-25 AT AT97919812T patent/ATE260846T1/de active
  • 1997-03-25 DE DE69727950T patent/DE69727950T2/de not_active Expired - Lifetime

Non-Patent Citations (1)

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