AU771654B2 - Non-continuous system for automatic self cleaning of permanent magnets or electromagnets - Google Patents

Description

Non-Continuous System for Automatic Self Cleaning of Permanent Magnets or Electromagnets Field of the Invention The field for this invention includes any type of industry which needs to transfer or transport bulk materials by means of conveyor belts or through chutes, on tables, inclined planes, vibratory transporters or any other form, such as the mining, metallurgical, agricultural, forestry, plastics, chemical, cellulose and paper industries among others. This non-continuous self cleaning system acts as a scraping device and cleaner of metals trapped by permanent magnets or electromagnets.

The majority of materials moved in bulk which are transported by conveyor belts or vibratory conveyors, transferred along chutes and across tables, inclined planes or other systems, require the magnetic separation of the iron particles which contaminate them or which can cause damage to processing equipment such as mills, crushers, pumps, reactors, valves, gates, presses, cookers, strip mills, sampling equipment, etc. or block 15 chutes and transfer grates, damage other transport equipment, etc.

Thus, the metallic and non-metallic mining industry, the food, construction, forestry, cellulose and paper, agricultural, plastic, metallurgical and chemical industries, the bulk loading of grain, coal, minerals, etc. all require permanent magnets or electromagnets either suspended or otherwise, over or under the equipment which 20 transports or transfers them, with any inclination or as the base of chutes, in order to separate the harmful [R:\LIBLL] 13352.doc:TCW WO 00/58186 PCT/US99/23383 2 contamination of iron. These magnets, in turn, need to have their magnetic surfaces cleared of such contaminants once they have been trapped.

The non-continuous, self cleaning system of magnets and electromagnets will displace and clean off the ferrous metals, avoiding their accumulation on the magnetic faces which would reduce their efficiency as separators, and will also avoid the trapped particles from falling or being brushed off again into the flow of materials due to the overload of particles on the magnetic separators.

BACKGROUND OF THE INVENTION Currently, there are several methods, mechanisms or systems in the industry for the self cleaning of permanent magnets or electromagnets. These are as follows: For Permanent Magnet Equipment Manual cleaning: No mechanism is used. The trapped iron is removed manually from the magnetic face of the separator.

Manual cleaning, with a manual mechanism: A manually operated sliding plate is used. The plate is made from a non-magnetic material, generally series 300 stainless steel, containing one or more metallic sections which move the trapped iron particles away from the coverage of the magnetic field. Some manufacturers call this mechanism a "stripper pan".

Another type of cleaner using a manual mechanism is the "arm stripper" which consists of a non-magnetic arm which is moved manually on a pivot from one corner of the magnetic face of the magnet, covering the whole surface.

Automatic cleaning: A self cleaning system, consisting of an endless rubber band or belt which revolves round the magnet, driven by a four or two pulley mechanism Printed from Mimosa 01/05/09 13:58:33 Page: 4 WO00/58186 PCTIUS99/23383 3 with shafts and bearings, one of which is powered by a motor and reduction gear drive system. The belt is equipped with metal or rubber sweeper strips, which slide the trapped iron particles away from the area covered by the magnetic field until they fall or are displaced to one side or in line, depending on the position of the magnet in relation to the flow of material and depending on the direction of travel of the belt.

For Electromagnetic Equipment Manual cleaning: In this case, the trapped iron particles can also be removed manually from the face of the separator. Generally, however, the -electromagnet is switched off so that the iron particles fall by gravity or are easier to remove manually.

In the case of suspended electromagnets, the iron particles either fall directly onto the transporter over which the magnet is suspended and are then removed manually, or it becomes necessary to move the equipment from its working position to avoid the iron particles falling into the material or into undesirable places, and once the magnet is clean, the equipment is returned to its original position.

Automatic cleaning: A self cleaning system identical to the one described for permanent magnets and for which it is not necessary to switch off the electromagnet.

Not all of these systems are operable on any surface or inclined plane which contain the material carrying the particles to be separated. Some of them are more suitable for equipment suspended over conveyor belts or over the Printed from Mimosa 01/05/09 13:58:35 Page: WO00/58186 PCTIUS99/23383 4 head pulleys of these. Others are more suitable over or as the base of chutes, tables or conveyors and vibratory feeders. There is no mechanism which can adequately cover the full range of possibilities.

The disadvantages of the foregoing methods, mechanisms and -systems for cleaning are basically those of inefficiency and danger for the operator, especially in the case of manual methods, with or without mechanical assistance, as they depend entirely on the skill of the person in charge of cleaning the surface of the magnet.

This person runs the risk of injury through being trapped by the magnetic field or by sudden release of the iron particles, whichcan also fall back into the material flow from which they should be separated. At the same time, these manual methods, with or without mechanical assistance, are slow, and therefore, relatively unproductive. Their speed will depend on the skill acquired by the operator to meticulously carry out the cleaning process in the minimum time.

The systems of automatic cleaning using a cleaning belt have the disadvantage of taking up too much space, especially in the case of those with two pulleys whose diameters must be greater than the height of the magnet.

The belts lose their alignment, especially when working on an inclined plane, and they stretch with use.

This requires continual adjustment to regulate belt tension and subjects the shafts and bearings of the drive and driven pulleys to mechanical stress. The belts and their sweeper strips are subject to continuous wear and the drive system must function without stoppages. These are high cost mechanisms due to the number of moving parts involved in the consequent wear and maintenance and lubrication Printed from Mimosa 01/05/09 13:58:37 Page: 6 requirements, etc. Their direction of expulsion of the trapped metal particles and direction of rotation are closely linked to the design of the magnets, and once they have left the factory, these are difficult to change or modify.

The obvious solution to the above problem is to have a cleaning mechanism which is not subject to the skill of the operator, which makes the best use of available space and which allows for the sweeping off, extraction and elimination of iron particles from permanent magnets or electromagnets once these particles have been attracted and trapped on their magnetic surfaces, using fewer components subject to wear and requiring maintenance. A mechanism with greater flexibility as regards the direction of discharge of the iron particles and not dependent on the position or inclination of the magnet and one which does not operate continuously, but only when necessary or when considered necessary. The mechanism should also be suitable for equipment suspended above conveyor belts or their head pulleys, over chutes or as the base of these, over tables, oo:- inclined planes, conveyors and vibratory feeders of any type. That is to say, it should be operable on any transporter or transfer surface carrying material which may contain iron particles which require separation. In other words, it should be more efficient and more versatile than current mechanisms. However, up to the present, no solution has been found which covers the desirable characteristics as described above.

Summary of the Invention 20 It is an object of the present invention to overcome or substantially ameliorate at least one of the above disadvantages.

In a first aspect, there is disclosed herein a self cleaning or automatic cleaning system for magnets used with material conveying equipment, said system comprising: a non-magnetic, grooved plate attached to the lower magnetic face of a magnet to be cleaned, a non-magnetic, wedge shaped sweeper with a grooved base adapted to slide longitudinally across the lower grooved face of said grooved plate, a pair of springs attached to opposing respective lateral sides of said sweeper and arranged to extend along the lateral sides of said magnet from the front face thereof to the rear face thereof or vice versa, a drive and transmission system including: a pair of tubes slotted their entire length on the underside and each extending longitudinally along the upper face of said grooved plate between a respective said spring and said magnet, [R:\LIBLL] I 3352.doc:TCW an endless screw mounted in each of said tubes, and a movable push nut mounted on each of said screws and having a pusher attachment which runs in the slot of the respective said tube, said push nuts being adapted to engage said sweeper and drive said sweeper into a firing position at which said springs are stretched, a latch adapted to retain said sweeper in said firing position until raised by a bar adapted to be moved by one of said nuts, raising of said latch releasing said sweeper to slide across said grooved plate lower face in a cleaning stroke and strike iron particles trapped by the magnetic field of said magnet and expel said iron particles outside the area 1o covered by said magnet, and an electrical system connected to limit switches for controlling said system.

In another aspect, there is disclosed herein a self cleaning or automatic cleaning system for magnets used with material conveying equipment comprising: a magnet supported by a base, a non-magnetic plate attached to the magnetic face of the magnet, a S 15 non-magnetic sweeper with a grooved base slidable across the lower surface of the plate, springs attached to each end of the sweeper and fixed to the base at a first end thereof, -oo means for moving the sweeper to a second end thereof stretching the springs, means for releasing the sweeper allowing it to be propelled along the grooved plate from a second o• i •.end to a first end thereof whereby the sweeper strikes particles trapped by the magnetic ooo 20 field and propels them outside the magnetic field of the magnet.

•In another aspect, there is disclosed herein a method for cleaning iron particles from magnets supported by a base used in conveying equipment comprising the steps of providing a sweeper slidable across the lower surface of the magnet, attaching springs to 0o the sweeper and to the base, stretching the springs by moving the sweeper from a first end to a second end of the base, releasing the sweeper allowing it to be propelled along the magnet, propelling iron particles outside the magnetic field of the magnet.

In another aspect, there is disclosed herein a non-continuous self-cleaning or automatic cleaning system for magnets comprising: a non-magnetic sweeper movably supported adjacent a magnetic surface, and a means for imparting a rapid forward motion to said sweeper; and, a face on said sweeper adapted to strike iron particles adhering to said magnetic surface expelling them therefrom.

[R:\LIBLL] 13352.doc:TCW The non-continuous system for automatic self cleaning of permanent magnets or electromagnets of the preferred embodiment is controlled by limit switches activated from a control panel, and may be used in any type of industry which transfers or transports materials in bulk, by means of a conveyor belt, especially in the mining, metallurgical and chemical industries. Iron particles trapped on the active face of the magnet are swept or wiped off by means of a mechanism which basically consists of a non-magnetic toothed sweeper running on a grooved plate attached to the magnet. This occurs through two guides, and the teeth of the sweeper make a perfect fit with the plate grooves. On the inside of the guide tubes there is a threaded rod, which when it revolves by means of a lo motor drive, displaces mobile nuts which push the sweeper and the springs attached to it and place it in position to carry out the cleaning operation. When one of the push nuts reaches a certain point, it raises a latch freeing the sweeper which, pulled by the springs, slides rapidly across the face of the magnet. The shape of this mobile sweeper allows it to expel or discharge the iron particles trapped on the active face of the magnet in its rapid forward sweep, and during its slow return movement, any fresh iron particles are allowed to pass over it and remain adhered to the magnet to be cleared by the next forward sweep.

The non-continuous, self cleaning system for permanent magnets and electromagnets proposed by a preferred embodiment includes the attachment of a grooved S-sheet or plate of non-magnetic material to the magnetic or active surface of the magnet over which a non-magnetic toothed sweeper operates. The function of both these elements is to prove a meticulous cleaning of the magnetic surface as the sweeper's teeth fit perfectly into the grooves of the sheet. The sweeper slides across on guides located on each side ofthe grooved [R:\LIBLL] 13352.doc:TCW WO 00/58186 PCT/US99/23383 7 sheet and these guides ensure that the sweeper and the sheet are kept in close contact. The sweeper is connected at each end to a spring and these springs are stretched when the sweeper is moved to its trigger point by the driven nuts on each side. The nuts are driven by the threaded rods on screws which revolve by means of an electric motor connected to each of them. These screws are housed in two tubes which protect them and which guide the moveable nuts. Once the sweeper is in place, it is held by a latch device which protrudes through the sheet or plate.

on one side of the mechanism. The moveable nuts are th'en returned to the opposite side by a counter clo6kwise rotation of the screws. On reaching the end of ts travel, one of the nuts lifts a bar attached to -the latch thus freeing the sweeper, which then sweepsacross the face of the magnet being pulled by the force of the stretched springs in the same way as a stone, is shot from a catapult.

The flat leading face of the ,zjweeper strikes the trapped iron particles, expelling them from the force of the magnet and they fall outside the area covered by the magnetic field. When the sweeper/ is slowly returned to its trigger point by the action of the moveable nuts being driven by the rotating screws, /any fresh iron particles attracted by the magnet after the, sweeper action, come into contact with the angled or wedge shaped trailing edge of the sweeper which allows the 'articles to jump over the sweeper without being loosened 6r falling off as they are held by the magnetic field and collect in the center of the active surface of thq' magnet. As the sweeper is non-magnetic, it does not attract the iron particles and allows them to pass over it. I'h other words, the sweeper slides between the sheet attached to the face of the magnet and the iron Printed from Mimosa 01/05/09 13:58:44 Page: 9 particles, which tend to stay in the same place and are then in position to be swept off when the sweeper is again triggered. The sweeper is stopped at the end of its run by means of shock absorbing springs placed on each side and is then ready to start a new cleaning cycle.

The positioning of the moveable nuts which push the sweeper back to its trigger point and the subsequent activation of the latch are controlled by limit switches which make contact with them and which, together with an electric control panel, allow the noncontinuous self cleaning system to be operated, either manually or automatically, by remote control or from a distance, by means of a sensor of the iron particles trapped by the magnet, with timers, computerized means or by an operator. A warning may be given of the start of the cleaning cycle or release of the wiper by a sound or visual alarm or both. The cleaning cycles may be recorded for operational control, maintenance or ooeo statistics.

The following advantages are gained by a preferred embodiment of the self Is cleaning mechanism proposed by this invention: S: It operates according to necessity, and does not function continuously as in the case of cleaning belts.

It requires less space than traditional methods as it does not project as far from .io 2 the case of the magnet, especially when these are placed over the belts and discharge laterally.

*It allows the iron particles to be discharged in any direction, regardless of the angle or suspension position of the magnet. In the traditional systems, for example, :o066.

[R:\LIBLL] I 3352.doc:TCW WO 00/58186 PCT/US99/23383 9 lateral discharge is not recommended when the magnets are installed on the outlets over the head pulleys as the transported material can be introduced between the magnetic face and the self cleaning belt.

Its direction of discharge can be easily modified in the field by changing the position of the complete system, as unlike the traditional systems, this is not in one unit with the case of the magnet, but i's only bolted to it.

It can be easily installed in any make of unit, old or new, with manual or automatic cleaning, when its original mechanism needs replacing.

Due to not having speed reducers, pulleys, shafts, bearings or rubber belts with sweeping strips, it is cheaper than the traditional system.

Due to its intermittent operation and the fact that it has fewer moving parts and that the parts that are in contact with the trapped iron particles are more resistant, it requires less maintenance and less use of spare parts.

Due to its discontinuous operation and less mechanical effort required to move the sweeper it consumes less energy and has lower powered motors.

The parts that are subject to wear and tear are easier to change and cost less than the belts of the traditional systems.

It is lighter than traditional systems.

Its operation can be controlled manually or automatically, on side or at a distance, by remote control, by sensors of the metal particles trapped on the magnets, with programmable logical controls (PLC) by computer, with timers, etc. This is not the case of the traditional systems, which must operate continuously without stopping.

Printed from Mimosa 01/05/09 13:58:48 Page: 11 Statistics on its cleaning cycles can be kept for operational or maintenance purposes.

Sound or visual alarms can be inclined to warn of the cleaning operation and discharge of iron particles.

It is safer for the operators due to not being in continual movement.

Brief Description of the Drawing(s) In order to complete this description and to better illustrate the characteristics of the toothed sweeper and the system of guides, endless screws, latch and the springs which contribute to its movement, seven drawing figures are attached to the description herein, forming an integral part of said description. The drawings illustrate, but are not limited to an example of the mechanism.

FIGURE 1 is an overhead view of the non-continuous, self cleaning mechanism for magnets.

FIGURE 2 is a front elevation of the non-continuous, self cleaning mechanism for magnets shown in Figure 1.

go .o* [R:\LIBLL] I 3352.doc:TCW .1 11 WO 00/58186 PCT/US99/23383 11 FIGURE 3 is a front view of the non-continuous, self cleaning mechanism for magnets taken along line 3-3 of Figure 1.

FIGURE 4 is a side view of the non-continuous, self cleaning mechanism for magnets shown in Figure 1.

FIGURE 5 is a side view of the non-continuous, self cleaning mechanism for magnets taken along line 5-5 in Figure 1.

FIGURE 6 is an under view of the left side of the noncontinuous, self cleaning mechanism for magnets.

FIGURE 7 is a left side overhead view of the noncontinuous, self cleaning mechanism for magnets.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S) From a study of the drawings, it can be seen that the non-continuous, self cleaning system or automatic cleaning system of permanent magnets or electromagnets, is formed by a non-magnetic, moveable, toothed sweeper arm 1 which slides across a non-magnetic grooved plate or sheet 2 which is attached to the face of the magnet 3. The sweeper arm 1 has at its ends perforated components 4 to which are connected one of the ends of the catapult springs 5 whose other ends are inserted in a perforation of the projecting plates 6, bolted to the forward edge of the non-magnetic grooved plate 2.

Each of the springs 5 is located below the sides of the magnet 3 and above the grooved plate 2, making a longitudinal movement from the front to the back of the mechanism and vice versa.

Between the springs 5 and the magnet 3, one each side, are located two longitudinal tubes 7 parallel to the sides of the magnet 3, having their ends closed and a slot running their whole length on the underside. The front and Printed from Mimosa 01/05/09 13:58:52 Page: 13 WO 00/58186 PCT/US99/23383 12 rear ends of these tubes 7 are fixed to the upper face or smooth side of the grooved plate 2 by means of supporting flanges 10,11. Inside the tubes 7 run threaded rods or screws 8 carrying moveable push nuts 14 with a lower pusher attachment. When the electric motor rotates, these nuts move the whole length of the screws 8 guided by the slots in the tubes. The motors 9 are located at the rear end of the tubes 7 and are connected to the screws 8. At the same time as the moveable nuts 14 push the sweeper arm to its trigger point at the rear end of the mechanism, they also stretch the springs 5 until they are under tension. The sweeper is kept in its trigger position by a latch 12 which projects through the lower side of the grooved plate or sheet 2 on the right hand side of the mechanism.

Once the sweeper 1 is in position, the endless screws 8 return the moveable nuts 14 to the front of the mechanism by reverse rotation of the motors 9. The right hand moveable nut 14, raises a bar, which in turn lefts the latch 12 freezing the sweeper 1 which, pulled by the tensioned springs, is swept across the face of the magnet, striking the iron particles which may have been trapped and expelling them in the same direction as its travel, outside the area of the magnetic field, thus cleaning the magnet 3.

To avoid possible accidents, the tubes 7 and the springs 5 are shielded by a protective covering 13.

It is not necessary to enlarge on this description for any expert to understand the scope of the invention and the advantages derived from its use.

The materials, drive system, triggering mechanism, shape, size and layout of the elements are subject to variation as long as the concept and essential character of the invention are unchanged.

Printed from Mimosa 01/05/09 13:58:54 Page: 14 WO00/58186 PCTIUS99/23383 13 The terms in which this invention is described should be taken in a broad and not limiting sense.

The foregoing specification sets forth the invention in its preferred, practical forms but the structure shown is capable of modification within a range of equivalents without departing from the invention which .is to be understood is broadly novel as is commensurate with the appended claims.

Printed from Mimosa 01/05/09 13:58:56 Page:

Claims (14)

1. A self cleaning or automatic cleaning system for magnets used with material conveying equipment, said system comprising: a non-magnetic, grooved plate attached to the lower magnetic face of a magnet to be cleaned, a non-magnetic, wedge shaped sweeper with a grooved base adapted to slide longitudinally across the lower grooved face of said grooved plate, a pair of springs attached to opposing respective lateral sides of said sweeper and arranged to extend along the lateral sides of said magnet from the front face thereof to the rear face thereof or vice versa, a drive and transmission system including: a pair of tubes slotted their entire length on the underside and each extending longitudinally along the upper face of said grooved plate between a respective said spring and said magnet, an endless screw mounted in each of said tubes, and a movable push nut mounted on each of said screws and having a pusher attachment which runs in the slot of the respective said tube, said push nuts being adapted to engage said sweeper and drive said sweeper into a firing position at which said i springs are stretched, a latch adapted to retain said sweeper in said firing position until raised by a bar adapted to be moved by one of said nuts, raising of said latch releasing said sweeper to slide across said grooved plate lower face in a cleaning stroke and strike iron particles S• trapped by the magnetic field of said magnet and expel said iron particles outside the area S"covered by said magnet, and an electrical system connected to limit switches for controlling said system.

2. The cleaning system of claim 1, wherein said sweeper is formed of stainless steel and shaped like a toothed wedge, whose teeth fit substantially perfectly into the grooves of said grooved plate.

3. The cleaning system of claim 1, wherein said sweeper is provided with guides on its lateral sides for sliding across the grooved plate.

4. The cleaning system of claim 1, wherein said sweeper has a raised straight leading face adapted to strike the iron particles trapped on the face of the magnet during the cleaning stroke thereof. [R:\LIBLL] 13352.doc:TCW The cleaning system of claim 1, wherein said sweeper has a wedge shaped trailing edge adapted to enable iron particles engaging said trailing edge whilst said sweeper is being driven into said firing position to pass over said trailing edge.

6. The cleaning system of claim 1, further comprising means for recording the cleaning cycles to be kept for operation and maintenance statistics.

7. A self cleaning or automatic cleaning system for magnets used with material conveying equipment comprising: a magnet supported by a base, a non-magnetic plate attached to the magnetic face of the magnet, a non-magnetic sweeper with a grooved base slidable across the lower surface of the plate, springs attached to each 1o end of the sweeper and fixed to the base at a first end thereof, means for moving the sweeper to a second end thereof stretching the springs, means for releasing the sweeper allowing it to be propelled along the grooved plate from a second end to a first end o. thereof whereby the sweeper strikes particles trapped by the magnetic field and propels them outside the magnetic field of the magnet. 15 8. The self cleaning or automatic cleaning system for magnetic conveyors S: having a magnet of claim 7 wherein the means for moving the sweeper to the second end comprises a drive and transmission system having endless screws housed in tubes extending longitudinally at the sides.

9. The self cleaning or automatic cleaning system for magnetic conveyors oooo having a magnet of claim 8 wherein the tubes are slotted on the underside generally along 00 their entire length. The self cleaning or automatic cleaning system for magnetic conveyors S•having a magnet of claim 8 wherein the tubes are installed between the springs and the magnet.

11. The self cleaning or automatic cleaning system for magnetic conveyors having a magnet of claim 8 further comprising push nuts which run on the endless screws within the tubes, and a pusher attachment which runs in the slot of the tube.

12. The self cleaning or automatic cleaning system for magnetic conveyors having a magnet of claim 11 wherein one of the push nuts at a predetermined point in its travel engages a latch freeing the sweeper.

13. The self cleaning or automatic cleaning system for magnetic conveyors having a magnet described in claim 7 further comprising: teeth on the sweeper that fit in grooves in the plate providing a guide for the movement of the sweeper across the plate.

14. A method for cleaning iron particles from magnets supported by a base used in conveying equipment comprising the steps of providing a sweeper slidable across [R:\LIBLL] I3352.doc:TCW 16 the lower surface of the magnet, attaching springs to the sweeper and to the base, stretching the springs by moving the sweeper from a first end to a second end of the base, releasing the sweeper allowing it to be propelled along the magnet, propelling iron particles outside the magnetic field of the magnet.

15. A non-continuous self-cleaning or automatic cleaning system for magnets comprising: a non-magnetic sweeper movably supported adjacent a magnetic surface, and a means for imparting a rapid forward motion to said sweeper; and, a face on said sweeper adapted to strike iron particles adhering to said magnetic lo surface expelling them therefrom.

16. The non-continuous self-cleaning or automatic cleaning system of claim 15 wherein said means for imparting a rapid forward motion to said sweeper is hydraulic. S. 17. The non-continuous self-cleaning or automatic cleaning system of claim 0go0 15 wherein said means for imparting a rapid forward motion to said sweeper is s15 pneumatic. S: 18. The non-continuous self-cleaning or automatic cleaning system of claim

64.6 wherein said means for imparting a rapid forward motion to said sweeper is mechanical impact. 19. The non-continuous self-cleaning or automatic cleaning system of claim 15 further comprising: o a plate having a first side and a second side; guide bearings supported on said sweeper and engaging said first side and said S°second side whereby said sweeper is freely movable along said plate. Self cleaning or automatic cleaning system for magnets, said system being substantially as hereinbefore described with reference to the accompanying drawings. Dated 20 September, 2002 Eriez Manufacturing Company Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON [R:\LIBLL] 3352.doc:TCW