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
  • B27B3/00—Gang saw mills; Other sawing machines with reciprocating saw blades, specially designed for length sawing of trunks
  • B27B3/02—Gang saw mills; Other sawing machines with reciprocating saw blades, specially designed for length sawing of trunks with vertically-reciprocating saw frame
  • B27B3/14—Arrangements for raising or lowering the feed rollers
• • 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
  • B27B25/00—Feeding devices for timber in saw mills or sawing machines; Feeding devices for trees

Definitions

• the present invention relates to a support device for supporting a log advancing through a frame saw, said device comprising one or more supporting elements positioned adja ⁇ cent to the saw frame.
• Frame saws represent the oldest known sawing technique for mechanically ripping round logs into various types of sawn timber.
• the frame saws in principle consist of a frame which is guided for reciprocating movement in a plane, pre ⁇ ferably in a vertical direction.
• the frame may be guided by means such as rollers, slides etc., and the movement may be provided by means of various mechanical systems of which the most usual comprises a crank shaft with a connecting rod.
• One or more parallel saw blades are strapped in the frame, and the log to be ripped is advanced towards the frame and the saw blades.
• the reciprocating saw blades will cut the log and rip it into a plurality of planks, boards, blocks etc. according to the size and shape' of the log and the positioning of the saw blade in the frame.
• the log is advanced towards the saw blades in a stable and linear fashion.
• This can be obtained by fixing one or both ends of the log in a trolley accompanying the log during the advancement ' thereof and preventing the log from rolling laterally or twisting.
• the log is usually fixed and supported by a plurality of rollers under, above and possibly also at the sides of the log immediately in front or upstream of the saw frame. These rollers will support the log adjacent the frame and are primarily intended to take up the reaction forces from the sawing operation.
• the rollers may also be rotationally driven and thereby pro ⁇ vide the necessary force for advancing the log.
• the advancement or feeding of the log can be obtained by a winch or the like pulling the log through the saw.
• strong riving bla es In order to prevent twisting of the log, strong riving bla es
• OMPI are often provided behind the saw blades.
• An object of the present invention is to stabilize a nonuniform log having lopped-off twigs in a manner allowing for irregularities in the log, while providing a fixed, rigid support capable of taking up the forces from the saw blades.
• This object is met according to the present invention by providing supporting elements adapted to be resiliently pressed into contact with the log with a predetermined force, and to be locked for fixedly supporting the log and taking up the forces from the saw blades during the entire working stroke thereof, said elements being releasable during at least a part of the return stroke to allow the elements- to adapt themselves to the varying shape of"the advancing log.
• the force with which the elements are pres ⁇ sed into contact with the log in released condition is adjustable in accordance with the weight and shape of the log.
• Each supporting element may be associated with an hydrauli system pressing the element into contact with the log.
• each suppor i g element may be associated with a mechanical device providing the force pressing the element into contact with the log.
• the supporting elem may be blocked during the working stroke by mechanical means such as wedges, stepped stops or brakes.
• the locking of the supporting elements may be achieved by means of a valve which when closed blocks the flow of hydraulic medium, thereby locking the supporting ele ⁇ ments. When the valve is open the supporting element is relea ⁇ sed. Further supporting elements may be arranged over the length of the log path. Such supporting elements are prefer ⁇ ably lockable like the previously defined supporting ele ⁇ ments. However, such locking may not be necessary in connec ⁇ tion with supporting elements positioned at a substantial distance from the saw frame.
• the supporting elements may consist of rollers or wheels, and in this case one or more of the rollers or wheels may be rotatably driven to provide the feeding movement of the log.
• the supporting elements are fixed and will not yield, so that they may take up the reaction forces from the sawing opera ⁇ tion.
• the supporting elements are released and may then freely adapt themselves to the shape of the log by being forced into contact therewith by the hydraulic or mecha nical means referred to.
• a new working stroke starts the supporting elements are locked in position to effectively support the log during the cutting operation.
• the system will operate particularly effectively if the known technique comprising a mounting of the saw blades with a suitable inclination relative to the path of reciprocation is used. In this case the log may be halted during the wor ⁇ king stroke and be advanced only during the return stroke. This will provide the greatest precision of the sawing opera ⁇ tion.
• the described device while easily adapting itself even to large irregularities and bends of the log, .wil at the same time provide a stable fixation of the log during the sawing operation without any tendency of yielding or twis ting under the effect of the relatively large reaction forces from the cutting operation of the saw blades.
• Even very nonunifor logs can be easily advanced and fixedly sup ⁇ ported in the frame saw without resulting defects in the sawn timber.
• the largest possible precision will be obtained, since the log will be supported in a stable and fixed manner during the sawing operation.
• Fig. 1 shows a support device using an hydraulic system.
• Fig. 2 shows a device using a mechanical system includin a counter weight and a wedge for bia ⁇ sing and locking the sup porting elements.
• Fig. 1 the round log 1 to be cut is advanced to the right as indicated by an arrow.
• a saw frame 3 is mounted for reciprocal movement up and down.
• the guides and the ope ⁇ rating system for the frame are not illustrated since they may be conventional.
• a plurality of parallel saw blades are strapped in the frame in a conventiona l manner .
• the log 1 is advanced aga ins t and th rough th e saw frame , whi l e be i ng sup ⁇ ported at the ends on two trolleys 2 running on ra i ls 11 .
• the trolleys 2 are des igned to allow the log 1 to be "fetched " and “delivered” through the saw frame past the saw blades withou t the trolley itself having to pass through the frame .
• the advancement or feed may be obtained by means of a winch (not shown ) pull ing the rear trolley forwards .
• a winch not shown
• a supporting element in the form of a roller 4 which is moun ⁇ ted at the end of a one-armed lever 13 mounted on a pivot 6.
• the roller 4 is pressed into contact with the log 1 by a pis ⁇ ton 12 of an hydraulic piston-cyl inder unit 5.
• Only one roller 4 is illustrated in Fig .
• Hydraulic liquid under pressure acts on one side of the pis ⁇ ton 12 in order to raise the roller 4 and press it into good contact with the log 1.
• the pressure of the hydraulic liquid may be obtained by means of an hydraulic liquid tank 7 posi- at a high level and communicating with the cylinder through a conduit 14.
• a valve 8 which may be actuated by cams . or dogs 9 . and 10 on the saw frame 3. The cam 10 will open the valve 8 when the saw frame
• O P liquid can be suppl ied and di spl a ced th rough th e open valve 8. Consequently , the log is held in a f i xed pos it ion during the working stroke , and the supporting roll er 4 wi ll adjust itself to the irregularities of the log during ea ch return stroke .
• the pressure of the hydraulic liquid in the cyl inder 5 may be provided in any su itable man ⁇ ner.
• pressure can be imparted to the hydraulic liquid in a closed tank by means of a gas cushion , a spring or weight loaded piston or the like .
• the valve 8 may alterna ⁇ tively be controlled by the operating mechanism for the saw frame through cams or by transmission of electromagnetic impulses. It is essential for a proper functioning of the device that the valve 8 is kept closed during the working stroke , so that the roller 4 is fixed and can take up the reaction forces from , the saw blades in the frame 3 , which forces will act on the log 1 in the direction of movement of the saw frame during the working stroke.
• the valve 8 must be open during the return stroke for a sufficient period to release the roller and allow it to adapt itself to the shape of the log during advancement thereof .
• the feeding means for advancing the log through the saw frame to be syncronized with the stroke of the saw frame , so as to be operative only when the supporting elements are released, the feeding being interupted during the working stroke.
• the pres ⁇ sure can be varied simply by increasing or reducing the pressure of the gas cushion , for instance by means of a
• a mechanical system is shown strictly diagra atically.
• the reference numerals 1, 2, 3 and 11 designate the same elements as in the embodiment in Fig. 1.
• the saw frame 3 is driven by a connecting rod 16 connected to a crankshaft having a flywheel 15.
• the supporting element may be a roller as in Fig. 1, but the element 17 shown in Fig. 2 is a plate with a curved upper side.
• the supporting element 17 is provided with a stem 18 guided for vertical reciprocal movement in a suitable guide 19. Through a two- armed lever 21 a weight 20 acts on the stem 18 to press the supporting element 17 into contact with the log 1.
• a “wedge” or stepped stop 26 is mounted at the end of a two- armed lever 24, and is biassed to a position below the lower end 27 of the stem 18 by means of a spring 25.
• a cam follower 23 At the other end of the two-armed lever 24 there is mounted a cam follower 23 which engages a cam surface 22 on the circumfe ⁇ rence of the flywheel 15.
• the cam surface 22 engages the cam follower 23
• the stepped stop or "wedge” 26 will be retracted from the position below the lower end of the stem 18, as illustrated in Fig. 2.
• the crankshaft rotates as indicated by the arrow 28, the "wedge” 26 will be retracted from the stem 18 when the saw frame 3 is moving upwards, i.e. during the return stroke.
• the supporting element 17 will the be freely movable in the guide 19, following the shape of the log 1 under, the influence of the weight 20.
• the saw frame 3 is moving downwards during its working stroke, there is no cam surface to influence the lever 24 through the cam follower 23, and the "wedge" 26 will then be pulled by the spring 25 to a position below the stem 18.
• the log 1 will then be rigidly supported by the supporting element 17, excep for a possible small downward movement which cannot exceed th pitch of the stepped stop 26.
• the log 1 is advanced only during the return stro ⁇ kes of the saw frame 3.
• the log may be advanced by means of a feeding device, which is not illustrated since it may be of a conventional type.

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Wood Science & Technology (AREA)
• Forests & Forestry (AREA)
• Sawing (AREA)
• Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
• Mushroom Cultivation (AREA)
• Load-Engaging Elements For Cranes (AREA)
• Soil Working Implements (AREA)
• Ladders (AREA)

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Applications Claiming Priority (1)

Publications (2)

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ID=19907188

Family Applications (1)

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• 1982
  • 1982-05-12 AT AT82901446T patent/ATE19019T1/de not_active IP Right Cessation
  • 1982-05-12 AU AU83971/82A patent/AU8397182A/en not_active Abandoned
  • 1982-05-12 WO PCT/NO1982/000027 patent/WO1983003996A1/en not_active Ceased
  • 1982-05-12 EP EP82901446A patent/EP0108049B1/de not_active Expired
  • 1982-05-12 DE DE8282901446T patent/DE3270362D1/de not_active Expired
• 1984
  • 1984-01-11 DK DK012284A patent/DK150730C/da not_active IP Right Cessation

Non-Patent Citations (1)

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