Classifications

• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02F—DREDGING; SOIL-SHIFTING
  • E02F7/00—Equipment for conveying or separating excavated material
  • E02F7/06—Delivery chutes or screening plants or mixing plants mounted on dredgers or excavators
• • 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
  • B07B1/18—Drum screens
• • 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
  • B07B1/28—Moving screens not otherwise provided for, e.g. swinging, reciprocating, rocking, tilting or wobbling screens

Definitions

• the present invention relates to the screening of such materials as earth, gravel and the like containing comparatively large-size objects, such as stones, root vegetables and the like, which are to be separated from the finer material. More precisely, the invention concerns a method and a device of the type recited in the preambles of appended claims 1 and 4, respectively, use being made of a rotatable screening drum which preferably is connect ⁇ ed to a working machine, e.g. a tractor with a front loader.
• This invention is based on the screening technique disclosed in EP-B1-0,178,656 (corresponding to SE-B-
• This prior-art technique employs a substantially grate-type screening basket which is connected to the front loader of a tractor and which, during screening, is rotated by means of a rotary shaft extending in the main direction of travel of the tractor.
• This prior-art screen ⁇ ing device does, however, suffer from a number of draw ⁇ backs which chiefly are related to the alignment of the rotary shaft and its sole mounting point.
• the forwardly-directed rotary shaft usually necessitates that the width of the screening basket be smaller than the track gauge of the tractor, since the forces generated by the rotational motion of the basket might otherwise jeop ⁇ ardise the stability of the tractor sideways. It has been found in practical use that the width of the screening basket should not exceed 1.7 m.
• US-A-4,005,755 which relates to a machine which can be connected to a front loader and is adapted to take up and screen earth.
• This machine com- prises a housing which essentially consists of two inte ⁇ gral end walls and a front grating. Inside the housing, there is an endless chain drive whose transverse elements have substantially the same width as the housing. Also this machine suffers from drawbacks similar to those dis- cussed above. Thus, there is a considerable risk that stones become wedged in the complicated chain drive. Fur ⁇ ther, the machine has a large number of movable parts, which is far from being an advantage.
• One object of the present invention is, therefore, to eliminate the above inconveniences by providing a simple, quick and efficient method for screening earth, gravel and the like, without necessitating any complicated equipment.
• Another iject of the invention is to provide a device for screening earth, gr ⁇ /el and the like, which obviates the above inconveniences and which is of simple construction and has but a few movable parts.
• Yet another object of the invention is to provide a screening device having simple and reliable drivinr means and capable of efficiently taking up the forces to which it is subjected during the screening operation.
• a further object of the invention is to provide a screening device easily connectible to a working machine, preferably to the front loader of a tractor vehicle, so that the device, by simple operation, can be moved into the earth or gravel to be screened and receive a suitable amount of material.
• the invention is based on the idea of moving a screening drum which forms part of the device and is disposed transverse to the main direction of travel of the working machine, into the earth to be screened and then raising it and rotating it in a first direction o effect screening.
• the drum is thereafter rotated in the opposite direction, whereby the large-size objects retain ⁇ ed in the drum are automatically discharged therefrom.
• any devices for closing the inlet opening of the drum as is the case in prior-art screening devices of similar kinds where e.g. hydrau- lically-operated grating and gates are used for opening and closing the inlet opening.
• Fig. 1 is a schematic perspective view showing a screening device according to the invention obliquely from in front
• Figs 2-5 are schematic cross-sections of a screening drum forming part of the device and shown in different operational positions.
• Fig. 6 is a perspective view obliquely from in front and Fig. 7 is a perspective view obliquely from below of a slightly modified screening drum which has been discon ⁇ nected from the other equipment.
• Fig. 1 illustrates a device designed in accordance with the invention for screening such materials as earth, gravel and the like.
• the material to be screened is a mixture of relatively large objects 1 in the form of stones, and fine-grained material 2 in the form of earth.
• the main component of the screening device is a screening drum generally designated 3 which, by means of a substantially horizontal rotary shaft 4, is mounted on a frame 5.
• the frame 5, which is of known type (see, for instance, GB-A-1,512,206), is in conventional manner provided with means for connection to a working machine, in this case the front loader 7 of a tractor 6.
• the frame 5 and the drum 3 mounted thereon can be lifted, lowered and tilted by means of the front loader 7.
• the screening drum 3 may be regarded as a body of revolution with respect to the axis of rotation or rotary shaft 4, and the circumferential surface of the drum 3 mainly consists of a curved screening element 8, one transverse edge of which is connected to a reinforcing metal sheet 9 in one piece (see Figs 6 and 7) and the other free, transverse edge of which extends into the drum 3. Further, the drum 3 has two integral vertical end walls 10, 11 of sheet metal, between which extend the curved screening element 8 and the flat reinforcing sheet 9. Both the screening element 8 and the reinforcing sheet 9 are connected, preferably by welding, to each other and to the periphery of the respective end wall 10, 11.
• a driving unit 12 which is mounted on the frame 5 and arranged on the outside of the end wall 11, rotates the rotary shaft 4 and, consequently, the er*--lre drum 3 mounted thereon.
• the driving unit 12 prefer-, ⁇ ly is a known hydraulic motor connected to one end of the rotary shaft 4. If need be, there may, of course, be arranged a hydraulic motor at each end of the rotary shaft 4.
• the rotary shaft 4 is, hcv-ever, freely mounted on the forwardly-directed part of the frame 5 at the end wall 10 (not shown).
• hydrau ⁇ lic lines and other equipment forming part of the hydrau ⁇ lic system are not shown in Fig. 1.
• the circumferential surface of the drum 3 is formed with an inlet opening 13 for the mater,al to be screened.
• the opening 13 is defined by the front edge of the reinforcing sheet 9, the forwardly-directed edge of the end walls 10, 11, and the extension of the screening element 8 directed into the drum 3, as will be discussed in more detail below.
• the drum 3 is moved, by means of the tractor 6, in the direction indicated by the arrow into the earth 1, 2 until a suitable amount of material has been fed into the drum 3 through the opening 13.
• the rotary shaft 4 is either locked by a pressure-reducing valve or a non-return valve (not shown) in the hydraulic system, e.g. in the hydraulic motor 12, or l a cked mecha- nically by a locking means (not shown) which is mounted on the frame 5 and can be operatively applied against the outside of the drum 3.
• a pressure-reducing valve or a non-return valve not shown
• a locking means not shown
• the screening drum 3 is rotated towards the tractor 6 in the direction indicated by the arrow, so that the fine material, i.e. the earth 2, is forced out of the drum 3 through the screening element 8, which preferably is a netting or grating.
• the large-size objects, i.e. the stones 1, that cannot pass through the screening element 8, are retained in the drum 3 by a wall 14 which is an extension of the screening element 8 and is directed into the drum.
• the wall 14 located in front of the opening 13 forms in the drum 3 a pocket 15 which, when the drum is rotated in the first direction, serves to retain the stones 1 inside the drum 3.
• the stones 1 are caused, when the drum is rotated further in the first direction, to roll away from the pocket 15 and via the wall 14 associated therewith to pass towards the inside of the reinforcing sheet 9.
• the pocket 15 and the wall 14 efficiently prevent the stones 1 from dropping out through the opening 13.
• the stones 1 impinge upon the reinforcing sheet 9, since this protects the screening element 8, which here is a netting.
• the reinforcing sheet 9 preferably has an angled portion 16 (see Fig. 2) which extends a distance onto the curved screening element 8 which thus is further protected from the impact by the stones 1.
• the wall 14 is preferably arranged essentially midway between the rotary shaft 4 and the opening 13.
• the inner free transverse edge of the wall 14 advantageously extends beyond the plane passing through the centre of the rotary shaft 4 and the point of intersection between the front edge of the reinforcing sheet 9 and the front, bottom corners of the end walls 10, 11.
• the e transverse edge of the wall 14 has to be located at a ⁇ -s- tance from the inside of the drum 3, i.e. at a distance from the inside of the reinforcing sheet 9.
• the free transverse edge of the wall 14 preferably is perfectly parallel to the rotary shaft 4, as are of course the two transverse edges of the reinforcing sheet 9.
• the drum 3 is preferably stopped in this position, whereuron it is taken, by the tractor 6, to an emptying station wnere it is rotated in the opposite direction, as illustrated by the arrow in Fig. 4.
• the stones 1 are allowed to leave the pocket 15, and the drum 3 is, after being turned a limited distance, situated in the emptying position shown in Fig. 5, where the stones 1 slide on the sheet 9 and out of the drum 3 through the opening 13.
• the drum 3 is preferably stopped in this emptying position, or is slightly turned further clockwise (with respect to Fig. 5) to be completely emptied.
• the frame 5 can be further tilted and/or shaken should any material have got stuck in the drum 3.
• Figs 1-5 the method according to the invention for screening material is clearly illustrated in Figs 1-5.
• the material 1, 2 is fed into the drum 3, which is first brought to a screening position, in which it is rotated in a first direction, the stones 1 being retained in the drum 3. Then, the drum 3 is brought to an emptying position, in which it is rotated in the opposite direction, so that the stones 1 are removed from the pocket 15 and discharged from the drum 3 through the opening 13.
• the screening device of this embodiment has proved to be particularly efficient.
• the drum was rotated at a speed of about 7-15 rpm, and especially good results were obtained at a speed of about 10-12 rpm.
• the drum was rotated about 4-5 revolutions in the first direction, and about 0.5-1 revolution in the opposite direction. All in all, this represents a shorter screening cycle than could be achieved in prior-art screening devices of similar type.
• a screening drum of this type should, to the largest possible extent, consist of a screening ele ⁇ ment.
• the practical tests mentioned above have shown that the drum is especially effective if about 70% of its cir- cumferential surface is made up of the screening element, about 15% thereof is made up of the reinforcing sheet, and about 15% thereof is made up the opening. It will, how ⁇ ever, be appreciated that these percentage figures are nothing but exemplifying target values.
• Figs 6 and 7 illustrate a slightly modified screening drum generally designated 3' which has been disconnected from the other equipment and whose drive shaft has been removed.
• the netting-type screening element 8 extends slightly beyond the two end walls 10, 11.
• the front edge of the reinforcing sheet 9 is bevelled, which makes it easier to move the drum 3' into the material to be screened.
• the bevelled portion is designated 17.
• Figs 6 and 7 also illustrate a vertical partition 18 which is arranged in the drum 3' and essentially has a stiffening function.
• the partition 18 may be replaced with a similar structure, e.g. spoke-like struts, arranged between the drive shaft and the netting.
• the partition as well as the rotary shaft may be dispensed with.
• the screening element 8 may also be replaceable in accordance with the contemplated degree of screening (diffeiant mesh widths).
• the entire drum 3' may be replaceable.
• the screening device according to the invention confers several major advan- tages, some of which have been discussed earlier in the text. Owing to the fact that the drum 3 is disposed transversely and mounted at two points on the frame 5, the pushing forces generated when the drum is being loaded are taken up very effectively. Also, the robust construction results in excellent force absorption when the drum 3 is rotated. In the tractor 6, the operator has a clear view into the drum 3 all the time, and may thus supervise the entire screening operation.
• the screening drum 3, 3' can be much wider than e.g. the screening device described in EP-B1-0,178,656 discussed by way of introduction.
• the inlet opening of the screening drum 3, 3' may advan ⁇ tageously have a width of up to about 3.0 m.
• Another con ⁇ siderable advantage to be emphasised is that the screening drum 3, 3' proper does not cor ain any movable parts at all.
• the driving means are simple and of standard design.
• the screening device may, for instance, be connect ⁇ ed to other working machines, and other frames, stands and driving means may be used. Further, the screening concept of the invention can be applied to other mate ⁇ rials than thos ⁇ referred to herein.

Landscapes

• Engineering & Computer Science (AREA)
• Mining & Mineral Resources (AREA)
• Civil Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structural Engineering (AREA)
• Combined Means For Separation Of Solids (AREA)
• Excavating Of Shafts Or Tunnels (AREA)
• Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
• Soil Working Implements (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=20380245

Family Applications (1)

Country Status (6)

Families Citing this family (8)

Family Cites Families (3)

• 1990
  • 1990-08-31 SE SE9002778A patent/SE466839B/sv not_active IP Right Cessation
• 1991
  • 1991-08-29 WO PCT/SE1991/000565 patent/WO1992004135A1/en active IP Right Grant
  • 1991-08-29 AT AT91916398T patent/ATE140883T1/de active
  • 1991-08-29 EP EP91916398A patent/EP0544806B1/de not_active Expired - Lifetime
  • 1991-08-29 DE DE69121203T patent/DE69121203T2/de not_active Expired - Fee Related
  • 1991-08-29 AU AU85237/91A patent/AU8523791A/en not_active Abandoned

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events