GB2386848A

GB2386848A - Screen assembly with access for maintenance

Info

Publication number: GB2386848A
Application number: GB0302694A
Authority: GB
Inventors: Ian Boast
Original assignee: BL Pegson Ltd
Current assignee: BL Pegson Ltd
Priority date: 2002-02-06
Filing date: 2003-02-06
Publication date: 2003-10-01
Anticipated expiration: 2023-02-06
Also published as: DE10305589A1; GB0302694D0; DE10305589B4; US6877610B2; GB0202706D0; US20030146315A1; GB2386848B

Abstract

A screen assembly 22 includes a conveyor 26 pivotably mounted beneath a screen 24 for segregation of fractions of material, for example from a mobile crusher 10 or in a material processing plant. Hydraulic cylinders (not shown) are used to selectively move telescopic arms (48, Fig 2) (only one of which is shown in the Figures), to raise or lower the conveyor 26 between operative position and inoperative positions. In the operative position the conveyor 26 is substantially parallel to the screen 24 for receiving material which has passed through the screen mesh, in use. In the inoperative position (Fig 4) the conveyor 26 is angularly displaced relative to the screen 24 about the pivot, to provide access to the underside of the screen 24, e.g. for maintenance purposes. Removable pins 50 are provided for releasably securing arms (42, Fig 4) which maintain the position of the conveyor 26 relative to the screen 24 in the operative position.

Description

TITLE: Screen assembly 2386848 Thepresentinventionrelates to a screen

assembly for amaterialprocessingplant, more particularly, but not exclusively, to a screen assembly for a mobile crusher.

Amobile crusheris amobileprocessingplantoftenusedinthe trituration of quarried materiels e.g. 5 stone. Mobile crushers are also used in the processing of aggregate from concrete or masonry waste, for example. A typical mobile crusher includes a chassis having amotor-driven crushing tool for crushing material, a hopper for feeding material to be crushed into the crushing tool, and a primary discharge conveyor for discharging crushed material which passes through the crushing tool. 10 The mobile crushermayinclude a screen assemblyhaving one or more screens for discharging different fractions of the crushed material from the crushing tool. A screen is a device for the segregation of a material into products of different sized particles. Typically, a screen consists of a mesh mounted on a frame, which is supported on springs and fitted with an unbalanced drive, such that the screen can be vibrated to aid the passage of a predetermined size of material through 15 the mesh.

On amobile crusher, a screen assemblyis mounted with a screen arrangedbeneath the primary conveyor at an angle to the horizontal. In use, crushed material is fed by the conveyor onto the upper end of the screen, such that the crushed material passes down over the vibrating screen mesh. Thus, particles of the crushed material smaller than the mesh openings are able to drop 20 through the screen, typically on to a secondary discharge conveyor for stock piling. The particles of cmshed material which do not pass through the mesh continue to travel down the screen until they are discharged, typically onto a further conveyor. The further conveyor may consist of a recirculating conveyor, for returning the oversize particles to the crushing tool, or a conveyor for discharging the oversize particles to a predetermined stock pile, for example.

The particles which pass through the screen mesh are either fed onto a second screen mounted directlybelowthe first screen end haying asmallermeshopeningsize for segregationinto smaller sizes, or onto a further secondary discharge conveyor, for example to be discharged on a predetermined stock pile.

5 Where a screen assembly is provided on a mobile crusher, it is important to be able to gain access to boththe top deck and underside ofthe or each screen, formaintenancepurposes. For example, itmaybe necessaryto repair adamagedmesh or to change the mesh for another have ing a different size mesh opening. It is also desirable to be able to alter the angle at which a screen is inclined in use, to optimise efficiency of the screening process.

10 Unfortunately, due to the limited space available on amobilecrusherofthetypedescribed above, the or each screen is usually disposed between the prunary discharge conveyor and the secondary discharge conveyor. Hence, access to the or each screen is restricted, which can lead to maintenance problems. Commonly, this is overcome by mounting a screen and an associated secondary conveyor on separate supporting frames, pivoted on the plaint chassis about the lower 15 ends of the frames, with the upper ends of each frame supported on pairs of cylinders. This arrangement enables the upper ends of each frame to be raised or lowered separately relative to one another. Access to the underside of a screen is therefore gained by lowering the secondary conveyor only, and access to the top deck of the screen is gained by lowering both the secondary conveyor and screen together.

20 However, this known solution is still restrictive. Moreover, there is an increasing need to reduce the weight of processing plant, such as mobile crushers, for transportation on public roads.

Undesirably, the use of additional supporting frameworks for the raisin" orlowering of screens and conveyors, as described above, increases the already substantial weight ofthe mobile crusher, which is typically between 40 to 75 tonnes.

25 It is an object ofthe invention to reduce, orsubstantiallyobviate, the disadvantagesreferredto above.

According to the present invention, there is provided a screen assembly for a material processing plant comprising a screen haying amesh for segregation offractions of materialplaced "hereon, a conveyorpivotablymountedbeneaththe screen, the conveyorbeingmovablebetweenanoperative position inwhich the conveyoris disposed substantiallyparallel to the screen, in use, forreceiving 5 material which has passed through the screen, and an inoperative or maintenance position in which the conveyor is angularly displaced about the pivot, for access to be provided to the underside of the screen, and means for releasably securing the attitude ofthe conveyor relative to the screen in the operative position.

The pivotable connection between the screen and conveyor is preferablyprovided at respective 10 ends ofthe screen end conveyor, such that, in the inoperative position, the free ends ofthe screen and conveyor are displaced away from one another, to allow substantiallymaximum access to the underside of the screen.

The means f or releasably securing the attitude of the conveyor relative to Me screen in the operative positionpreferablyconsists of at feast one connectingmemberhavingtwo ends, one end connected 15 to the conveyor and the other end connected to the screen, and at least one end ofthe connecting member being releasably connectable to the conveyor or screen respectively.

The means for releasably securing the attitude ofthe conveyorrelative to the screenmayinclude at least one removable pin.

Conveniently, the screen assemblyincludes means for connecting the screenassemblyto amaterial 20 processing plant.

The screen assembly may include a subirame connectable to a material processing plant, for mounting the screen assembly on the plant.

Preferably, the screen assembly is pivotablymounted on the means for connecting the screen assemblyto amaterialprocessingplant, forpivotablemovement ofthe screen assemblyrelative to the plant, in use.

The means for connecting the screen assembly to a material processing plant may include at least 5 one telescopic member having two ends, one end of the at least one telescopic member being connected to the screen assembly, and the other end ofthe at least one telescopic memberbeing connectabletothematerialprocessingplant, forraising orlowering one end ofthe screen assembly relative to the plant.

Preferably, the at least one telescopic memberincludes ahydraulic cylinder for selectivelymoving 10 the telescopic member between an extended position and a retracted position.

The underside ofthe screen assemblymayinclude a support member for supporting the screen assembly in a lowered position, in use.

The inventionwilluowbe described, bywayofexample only, with reference to the accompanying drawings, in which: 15 Figure 1 is a side view showing a mobile crusher incorporating a screen assembly according to the invention in an operative position; Figure 2 is diagrammatic side view of part of the mobile crusher shown in Figure 1; Figure 3 shows the part of the mobile crusher of Figure 2, with the screen assembly in a lowered position; and 20 Figure 4 shows the part ofthe mobile crusher of Figure 2, with a conveyor ofthe screen assembly in a lowered position.

. 5 Refernng to Figure 1, amobile crusheris indicated generally et 10 andincludes a chassis 12 having a motor-driven crushing tool 14 for crushing material, a hopper 16 for feeding material to be crushedinto thecrushingtool 14, andaprimarydischarge conveyor 18 for discharging the crushed material. The chassis 12 is connected to atrackedunder-carriage 20 to enable the mobile crusher 5 10 to be moved around a quany, for example.

The mobile crusher 10 isprovidedwithscreen assemblyindicated at 22 mounted on the chassis 12 bymeans of asubirame23 on the opposite side ofthe crushing tool 14 to the hopper 16. The screen assembly 22 includes a screen 24 for segregating fractions of crushed material, and a secondary discharge conveyor 26. The screen 24 is of a known construction having a mesh (not 10 visible) mounted on a frame 30, which is fitted with an unbalanced drive 32, for vibrating the screen 24, in use. The mobile crusher 10 also includes areciTculatingconveyor 34 in communication with the screen assembly.

All of the conveyors mentioned in the above description are endless belt conveyors.

In use, material to be crushed, e.g. stone material produced from a quarry, is placed in the hopper 15 16 and fed into the crushing tool 14 where it is crushed. Crushed material passes through the crushing tool 14 on to the primary discharge conveyor 18 and thence to the upper end ofthe primary discharge conveyor 18.

In the operative position, as shown, the screen 24 is disposed at an angle to the horizontal and crushed material is fed from the primary discharge conveyor 18 onto the upper end ofthe screen 20 24. The crushed materialis passed onto the vibrating screen mesh Thus,particles ofthe crushed material smaller than the mesh openings are able to drop through the screen 24 on to the secondary discharge conveyor 26. The oversize particles of crushed material remaining on the screen mesh continue to travel down the screen 24 until they are discharged onto the recirculating conveyor 34.

The recirculating conveyor 34 returns the oversize particles to the crushing tool 14 for re 25 processing. The smaller sized particles travel up the secondary discharge conveyor 26 to be discharged for stock piling.

The screen assembly 22 can be seen more clearly in Figure 2 which shows the subframe 23 and the communication between the screen assembly 22 and the recirculating conveyor 34.

The subframe 23 consists of apair of horizontal members 38 and apairofvertical members 40, only one of eitherbeingvisiblein the drawings. Eachhorizontalmember38 is securably connected 5 to an associated vertical member 40, to form a substantially right angled truss configuration, as shown. The free end of each horizontal member 38 is securably connected to a lower portion of the chassis 12, and the free end of each vertical member 40 is connected to an upper portion of the chassis 12, in use, as can be seen in Figure 1.

The frame 30 is pivotably connected to the subframe 23 adj acent the lower end of each vertical 10 member 40. The secondary discharge conveyor 26 is pivotably connected to the underside ofthe frame 30, and is releasablyheld in aposition substantiallyparallel to the screen, as shown inFigures 1 and 2, bymeans of apair of struts 42, only one of which is visible in the drawings. The lower end of each strut 42 is pivotably connected to the secondary discharge conveyor 26 adj acent its free end, to the right as viewed in the drawings. The upper end of each strut 42 is removably 15 secured to the frame 30 by means of pins 44.

A support foot 46 extends transversely across the underside ofthe secondary discharge conveyor 26, for supporting the screen assembly in a non-operative position, as will be described below.

Apairoftelescopic tubes 48 are provided on the screenassembly22, only one of whichis visible in the drawings. The lower end of each telescopic tube 48 is pivotably connected to the upper side 20 ofthe frame 30 adjacent its right hand end, as viewed in the drawings. The upper end of each telescopic tube48 ispivotably connected to anupperportion ofthe chassis 12, in use, as canbe seen in Figure 1. The telescopic tubes 48 include intemal hydraulic cylinders for selective movement ofthe tubes 48 between a refracted position (shown in Figures 1) and an extended position (shown in Figure 3). The telescopic tubes are secured in e retracted position shown in 25 Figure 1 by means of removable pins 50.

In the event that access to the upper side ofthe mesh is required, e.g. formaintenance, the pins 50 are removed to enable the screen 24 and secondarydischarge conveyor 26 to pivotwithrespect to the crusher 10, clockwise as viewed. The hydraulic cylinders move the telescopic tubes 48 fromtheretractedpositionto the extended position of Figure 3. In this position, the support foot 5 46 comes into contact with the ground, to support the screen assembly22. Thus, maximum access to the upper side of the screen 24 is provided between the angle of elevation of the primary discharge conveyor 18, to enable the upper side of the mesh to be dealt with, as required.

If access to the underside ofthe mesh is then required, the telescopic tubes 48 are moved to the retracted position and the pins 50 are reintroduced to secure the screen assembly 22 in the position 10 shownin Figures 1 and2. Thepins44arethenremovediromtheconnectionbetweentheframe.

30 end the struts 42, to enable the secondarydischarge conveyor26 topivotwithrespecttothe screen 24, clockwise as viewed, to the position shown in Figure 4. In this position, the support foot 46 comes into contact with the ground, to support the secondary discharge conveyor 26, independentlyfromthe screen24. Thus, the attitude oftheconveyor26 relative to the screen24 15 canbe altered to allow maximum access to the underside ofthe screen24, to enable the underside of the mesh to be dealt with, as required.

Although the screen assembly22 has been described with respect to asubtrame bymeans of which the screen assembly 22 is mounted on a mobile crusher chassis 12, it will be appreciated that the screen assembly 22 could be adapted to be secured directly on to the chassis of a mobile crusher, 20 without the need for a subframe. For example, the chassis ofthe mobile crusher could be specially formed to accommodate such a screen assembly 22.

Whilst the invention has been described with respect to a mobile crusher, the invention could also housed on other kinds of materialprocessingplanthaving a similar construction, such as awood processing plant having a shredding tool, as opposed to a Inching toot or any static crushing plant.

Claims

Claims

1. A screen assembly for a materiel processing plant comprising a screen having a mesh for segregation offractions of material placed Hereon, a conveyorpivotablymountedbeneath the screen, the conveyor being movable between an operative position in which the 5 conveyor is disposed substantiallyparallelto the screen forreceivingmaterial which has passed through the screen, in use, and an inoperative or maintenance position in which the conveyor is angularly displaced about the pivot, for access to be provided to the underside ofthe screen, and means for releasably securing the attitude ofthe conveyor relative to the screen in the operative position.

10 2. A screen assembly as claimed in claim 1, in which the pivotable connection between the screen end conveyoris provided atrespective ends ofthe screen end conveyor, such that, in the inoperative position, the free ends ofthe screen and conveyor are displaced away from one another, to allow substantially maximum access to the underside of the screen.

3. A screen assembly as claimed in claim 1 or claim 2, in which the means for releasably 15 securing the attitude ofthe conveyorrelativeto the screenin the operative position consists of at least one connecting member having two ends, one end connected to the conveyor and the other end connected to the screen, and at least one end ofthe connecting member being releasably connectable to the conveyor or screen respectively.

4. A screen assemblyasclaimedinanyofclaims 1 to 3, in which the means for releasably 20 securing the attitude ofthe conveyorrelative to the screen includes at least one removable pin. S. A screen assembly as claimed in any preceding claim, in which the screen assembly includes means for connecting the screen assembly to a material processing plant.

6. A screen assembly as claimed in any preceding claim, in which the screen assembly

includes a subframe connectable to a material processing plant, for mounting the screen assembly on the plant.

7. A screen assembly as claimed in claim 5 or 6, in which the screen assembly is pivotably mounted on the means for connecting the screen assembly to a material processing plant, 5 for pivotable movement of the screen assembly relative to the plant, in use.

8. A screen assembly as claimed in any of claims claim 5 to 7, in which the means for connecting the screen assembly to a material processing plant includes at least one telescopic memberhavingtwo ends, one end ofthe at leastonetelescopicmemberbeing connected to the screen assembly, end the over end ofthe at least one telescopic member 10 being connectable to the material processing plant, for raising or lowering one end ofthe screen assembly relative to the plant.: 9. A screen assembly as claimed in claim 8, in which the at least one telescopic member - i includes a hydraulic cylinder for selectivelymoving the telescopic memberbetween an extended position and a retracted position...

15 10. A screen assembly es claimed in anypreceding claim, in which the underside ofthe screen! assembly includes a support member for supporting the screen assembly in a lowered position, in use.

11. A material processing plant incorporating a screen assembly as claimed in any of claims 1 to 10.

20 12. A mobile crusher incorporating a screen assembly as claimed in any of claims 1 to 10.

13. A screen assembly as hereinbefore described with reference to the accompanying drawings.

it. 14. Amaterialprocessingplantincorporatingascreen assemblyas hereinbefore described with reference to the accompanying drawings.

15. A mobile crusher incorporating a screen assembly as hereinbefore described with reference . to the accompanying drawings.