Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
  • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
  • B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
  • B07B1/12—Apparatus having only parallel elements
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
  • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
  • B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
  • B07B1/46—Constructional details of screens in general; Cleaning or heating of screens

Definitions

• a known screening device includes a chute arranged upon a bottom frame, by which the chute is provided with an upper bottom which includes a screening grid consisting of mutual parallel screening rods, and is brought to vibrate relative to the frame by help of a vibrating device.
• the bottom frame is provided with longish carriers, which are arranged projecting up between the screening rods so that gaps are obtained between the rods.
• the screening rods performs a to-and-fro movement relative to the carriers, by which stuff with a piece size less or equal to the width of the gaps are falling through the screening grid and will be picked up on a lower botton arranged on the chute.
• the purpose with the present invention is to satisfy the wishes mentioned above.
• the purpose has been achieved by an invention which is constituted by a method for screening with a screening device which partly shows the same members as the known screening device and which is characterized in that the carriers is brought to vibrate partly relative to the bottom frame and partly relative the chute with the screening rods, by which the chute preferably is vibrating in the same plane as the carriers.
• the relative movement between the screening rods and the carriers is controlled by a mutual phase displacement of these respectively movement of vibration.
• the invention also includes a screening device which is characterized in that the carriers are movably arranged on the frame.
• the carriers are connected to the frame by struts, which include a spring device.
• the vibrating movement of the carriers thereby is effected by a vibration device which is attached to any of the struts.
• the vibration movement of the chute and the screening rods is effected by a vibration device attached on the frame and which is connected with the chute.
• the vibration device thereby preferably is constituted by a crank device which is driven by an electrical motor.
• the carriers and the chute are vibrated by crank devices attached to the frame, whose crank motion is controllable for adjusting of a mutual phase displacement of the two vibration movements.
• the carriers are provided with a mass, which is considerably less than the one of the chute, by which the carriers easier can be brought to vibrate with a higher frequency than the chute.
• the screening method in accordance with the invention is not limited to a division of a stuff into two fractions. By providing the chute with several bottoms a division in several fractions can be achieved.
• the method is in particular active by screening wooden chips, but is not limited to this kind of stuff.
• the method also can be used e.g. to separate gravel from wooden chips and the like.
• Figure 1 shows a screen for transporting and screening of wooden chips as seen fron one side.
• Figure 2 shows the screen in accordance with figure 1 in a cross-section.
• the screen in accordance with the example includes a chute 1 with an U-formed cross-section, which is carried by a frame 2 by suspension bars 3.
• the chute 1 is provided with an upper bottom 4 and a lower bottom 5.
• a screening aperture is arranged in the upper bottom 4 of the chute, which is covered by a screening grid consisting of mutually parallel screening rods 6 made of round iron.
• the frame 2 futher carries two loop-formed struts 7 whose attachements in the frame 2 consist of plate springs 8 which can be bent in the longitudinal direction of the chute 1.
• the loop struts 7 are twistable connected mutually by longish carriers 9 made of flat iron which are arranged edgeways so that one carrier 9 projects up between two screening rods 6 so that gaps are obtained between the screening rods 6 and the carriers 9.
• a vibrator 10 is arranged, which oscillations coincides with the bending plane of the plate springs 8.
• the chute 1 futher is connected to the frame 2 by a crank vibrator 11, which stroke length and number of revolutions can be adjusted relative to the carrier vibrator 10 which oscillations also is adjustable.
• the wooden chips which have to be screened is feeded into the chute 1 at the arrow against the upper bottom 4 and is moved by the shaking movement of the chute 1 effected by the crank arm vibrator 11 down to the screening grid where chips having a piece size less than the gap between the screening rods 6 and the carriers 9 is brought to fall through down to the lower bottom 5 in order to be moved on by the shaking movement of the chute 1 and away form it at the arrow from the lower bottom 5.
• the coarse fraction which pass over the screening grid is moved on by the shaking movement of the chute 1 and out from this one at the arrow from the upper bottom 4.
• the two fractions are transported ahead separately by help of following conveyors.
• the chute 1 and the screening rods 6 is controlled relative to the loop struts 7 and the carriers 9 by help of control devices as e.g. guides or other in itself known devices which are not shown in the figures.
• control devices as e.g. guides or other in itself known devices which are not shown in the figures.
• the gap between the screening rods 6 and the carriers 9 has a constant width at the relative movement between the screening rods 6 and the carriers 9, which in its turn gives a moore exact limit between the two fractions that are separated in the screen.
• Such an exact fractionating has not earlier been possible to achieve for instance by help of the known screening device mentioned above, where the carriers are firmly connected to the base of the device and where the chute with the screening grid is not provided with any guide to the base, e.g. indirectly the carriers which projects in the screening grid.
• Eventually play which arise by wearing of the suspension attachements brings the chute and the screening grid to move also sideways causing a varying width of the gaps between the screening grid and the carriers.

Landscapes

• Combined Means For Separation Of Solids (AREA)
• Jigging Conveyors (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20352792

Family Applications (1)

Country Status (5)

Cited By (1)

Families Citing this family (13)

Citations (2)

Family Cites Families (10)

• 1983
  • 1983-10-06 SE SE8305500A patent/SE435687B/sv unknown
• 1984
  • 1984-06-29 AU AU31571/84A patent/AU3157184A/en not_active Abandoned
  • 1984-06-29 EP EP84902954A patent/EP0188416A1/en not_active Withdrawn
  • 1984-06-29 WO PCT/SE1984/000248 patent/WO1985001456A1/en unknown
  • 1984-06-29 US US06/741,308 patent/US4664790A/en not_active Expired - Fee Related

Patent Citations (2)

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