Wear part for a crusher

A distributor plate adapted to be releasably mounted on a horizontal lower disc of a rotor of a vertical shaft impact crusher. The rotor has an opening for the intake of material to be crushed and at least one outflow opening for material leaving the rotor. The distributor plate is an equilateral polygon as seen from above.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a distributor plate adapted to be releasably mounted on a horizontal lower disc of a rotor of a vertical shaft impact crusher, said rotor having an opening for the intake of material to be crushed and at least one outflow opening for material leaving the rotor.

The present invention also relates to a rotor for a vertical shaft impact crusher, the rotor having an opening for the intake of material to be crushed, at least one outflow opening for material leaving the rotor, and at least one lower wear plate and a distributor plate releasably mounted on a horizontal lower disc of the rotor.

BACKGROUND ART

Vertical shaft impact crushers (VSI-crushers) are used in many applications for crushing hard material like rocks, ore etc. U.S. Pat. No. 3,154,259 describes a VSI-crusher comprising a housing and a horizontal rotor located inside the housing. Material that is to be crushed is fed into the rotor via an opening in the top thereof. With the aid of centrifugal force the rotating rotor ejects the material against the wall of the housing. On impact with the wall the material is crushed to a desired size. The housing wall could be provided with anvils or have a bed of retained material against which the accelerated material is crushed.

The rotor of a VSI-crusher usually has a horizontal upper disc and a horizontal lower disc. The upper and lower discs are connected with a vertical rotor wall. The upper disc has an aperture for feeding material into the rotor. The material lands on the lower disc and is then thrown out of the rotor via openings in the rotor wall.

The material exerts an impact force and wear on the lower disc. To ensure a long life of the lower disc it is usually provided with a distributor plate. The distributor plate, which is located at the centre of the lower disc, is made from a material that is resistant to impact and wear.

In U.S. Pat. No. 3,767,127 to Wood a deflection disc assembly is described. The deflection disc has an outer ring and a core member. A central stud passing through the core member and threadedly engaged to the rotor shaft holds the deflection disc in position in the rotor.

U.S. Pat. No. 4,690,341 to Hise describes a flat centre wear plate which is fixed to the rotor shaft by a bolt.

WO 01/30501 describes a distributor comprising a first part having an inclined surface and a second part with a flat surface. A bolt holds the first and second parts fixed to a rotor shaft.

The distributor plates described above do not have a very long life and cause a rather long down time when they need to be replaced. To make it possible for a person working with the rotor to replace the distributor plate it is often necessary to dismantle the top of the rotor.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a distributor plate which has a longer life and which decreases the down time required for maintenance of the rotor.

This object is achieved with a distributor plate according to the preamble and characterised in that the distributor plate is an equilateral polygon as seen from above.

An advantage with this distributor plate is that its life is greatly increased. The polygonal shape provides straight side edges which decrease the wear, particularly at the periphery of the distributor plate. A possible explanation is that much of the wear at the periphery of the distributor plate may be caused by dust loaded air streams circulating inside the rotor. Those air streams may be hindered by the straight side edges thus reducing the wear. A polygon has several straight side edges and would thus be able to efficiently hinder any dust loaded air streams.

Preferably the distributor plate has a shape chosen among triangular, square, hexagonal, octagonal and nonagonal shapes. An advantage with these particular shapes is that they are particularly efficient in hindering dust loaded air streams from circulating inside the rotor. In particular the hexagonal, octagonal and nonagonal shapes are also very robust to large pieces of material impacting the distributor plate. Still more preferably said polygon is an equilateral polygon, the number of sides of the polygon being chosen such that the number of sides is 1, 2 or 3 times the number of outflow openings of the rotor to which the distributor plate is to be mounted. An equilateral polygon makes it easier to balance the rotor. The distributor plate should have at least one side edge corresponding to each outflow opening of the rotor. If the number of sides of the distributor plate is 2 or 3 times the number of outflow openings it is possible to turn the distributor plate after some time in operation such that the sides being adjacent to the outflow openings is changed. Thus the life of the distributor plate is prolonged. Preferably the number of sides is 2 times the number of outflow openings of the rotor. This design has proven to give both a long life, possibly due to the fact that such a number of sides are especially efficient in hindering the rotating air streams inside the rotor, and the possibility to turn the distributor plate after some time of operation to further increase its life.

Preferably at least one straight side edge of the distributor plate is adapted to be parallel to an outflow direction of material leaving the rotor and to be parallel and adjacent to a face of a lower wear plate protecting the lower disc from wear. This design has proven to give a long life for both the distributor plate, the lower wear plate and the lower disc due to the fact that swirling of dust loaded air streams on the lower wear plate and on the lower disc is efficiently prevented by the distributor plate when located in this relation to the lower wear plate and to the direction of material leaving the rotor. It is also easy to make the distributor plate fit with a horizontal wear plate extending from a position close to the centre of the rotor and towards the outflow opening.

According to a preferred embodiment the distributor plate at the centre of its lower face has a recess adapted to make the distributor plate horizontally turnable around a vertical shaft mounted on the lower disc, such that the position of the distributor plate in relation to the lower disc may be adjusted before mounting the distributor plate. The recess makes it easy to centre the distributor plate on the rotor. After centring the distributor plate it may be turned around the shaft until the correct position of the edge/-s is obtained, the distributor plate still being safely centred. It also becomes easy to turn the distributor plate to some degree after it has become worn. This makes it possible to quickly turn the distributor plate to a new position without having to dismount the rotor. Thus maintenance stops become quick and efficient. Still more preferably the recess extends only through a part of the thickness of the distributor plate, the upper face of the distributor plate thus being unaffected by said recess. An advantage with this design is that the upper surface of the distributor plate obtains a much better impact and wear resistance since it is unbroken. The central part of the distributor plate is exposed both to heavy impact wear and possibly also to wear caused by dust loaded air streams circulating inside the rotor. The risk of rocks breaking a central bolt and the risk of an excessive wear of a central bolt or of a cap protecting a central bolt is thus avoided with the design of the present invention. Also it becomes easier to manufacture the distributor plate with the unbroken upper surface, in particular if the upper surface is to be provided with a layer of extra resistant material.

Preferably the upper face of the distributor plate comprises an unbroken layer of a hard metal, such as tungsten carbide. Such a layer of hard metal will substantially prolong the life of the distributor plate and thus decrease maintenance costs.

According to a preferred embodiment the distributor plate comprises mounting means located at a vertical side edge of the distributor plate and adapted for the mounting of a vertical support fixing the distributor plate to the lower disc of the rotor. An advantage with such mounting means is that they do not interact with the upper surface of the distributor plate. Another advantage is that the distributor plate will provide some protection for the mounting means located below the actual material flow. The mounting means may also be fitted and removed without having to lift the entire distributor plate.

It is another object of the present invention to provide a rotor which require less down time for maintenance.

This object is achieved with a rotor according to the preamble and characterised in that the distributor plate is an equilateral polygon as seen from above, at least one straight side edge of the distributor plate being parallel to an outflow direction of material leaving the rotor and being parallel to and adjacent to a face of the lower wear plate.

An advantage of this rotor is that the polygonal shape of the distributor plate decreases the wear inside the rotor and thus maintenance stops may be made less frequently. The straight side edge of the distributor plate fit with the adjacent and parallel face of the wear plate to hinder any wear at the underlying lower disc of the rotor.

FIG. 1shows a rotor1for use in a VSI-crusher. The rotor1has a roof in the form of an upper disc2having a top wear plate3and a floor in the form of a lower disc4. The lower disc4has a hub6, which is welded to the disc4. The hub6is to be connected to a shaft (not shown) for rotating the rotor1inside the housing of a VSI-crusher.

The upper disc2has a central opening8through which material to be crushed can be fed into the rotor1. The upper disc2is protected from wear by upper wear plates10and12. The upper disc2is protected from rocks impacting the rotor1from above by the top wear plate3. As is better shown inFIG. 2the lower disc4is protected from wear by three lower wear plates14,16and18.

The upper and lower discs2,4are separated by and held together by a vertical rotor wall which is separated into three wall segments20,22and24. The gaps between the wall segments20,22,24define outflow openings26,28,30through which material may be ejected against a housing wall.

At each outflow opening26,28,30the respective wall segment20,22,24is protected from wear by three wear tips32,34,36located at the trailing edge of the respective wall segment20,22,24.

A distributor plate38is fastened to the centre of the lower disc4. The distributor plate38distributes the material that is fed via the opening8in the upper disc2and protects the lower disc4from wear and impact damages caused by the material fed via the opening8.

During operation of the rotor1a bed40of material is built up inside the rotor1against each of the three wall segments20,22,24. InFIG. 3only the bed40located adjacent to the wall segment20is shown. The bed40, which consists of material that has been fed to the rotor1and then has been trapped inside it, extends from a rear support plate42to the wear tips32,34,36. The bed40protects the wall segment20and the wear tips32,34,36from wear and provides a proper direction to the ejected material. The dashed arrow A describes a typical passage of a piece of rock fed to the rotor1via the central opening8and ejected via the outflow opening26. The arrow R indicates the rotational direction of the rotor1during operation of the VSI-crusher.

Each wall segment20,22,24is provided with a cavity wear plate44,46,48, each preferably having three cavity wear plate portions. The cavity wear plates44,46,48protect the rotor1and in particular the wear tips32,34,36from material rebounding from the housing wall and from ejected material and airborne fine dust spinning around the rotor1.

InFIG. 4the regularly hexagonal shape of the distributor plate38is shown in greater detail. The distributor plate38has six equilateral, vertical side edges50,52,54,56,58,60. The side edge50is substantially parallel to the outflow direction B of the material leaving the rotor1via the outflow opening26. The side edge50is also parallel and adjacent with the face62of the wear plate14. In a similar way the side edge58is adjacent to the face64of the wear plate16and the side edge54is adjacent to the face66of the wear plate18. The distributor plate38has a central flat area68from which a sloped surface70of the distributor plate38extends towards the side edges50,52,54,56,58and60.

The distributor plate38is removably fixed to the lower disc4with the help of three vertical supports72,74,76fitted to the side edges52,56,60that are not adjacent to a face of a wear plate. Thus the vertical supports72,74,76are located at some distance from the typical rock passage indicated with the arrow A.

As is shown inFIG. 5the distributor plate38rests on a mounting plate78. The mounting plate78has the same hexagonal shape as the distributor plate38as seen from above. The mounting plate78is bolted to the hub6and thus to the lower disc4. A vertically mounted central bolt80extending through the mounting plate78is bolted at the centre of the hub6. The distributor plate38has a central cylindrical recess82at its lower face84. The diameter and depth of the recess82is adapted to house the circular top of the bolt80such that the bolt80centres the distributor plate38on the lower disc4. The lower face84of the distributor plate38may slide on the upper surface of the mounting plate78when a locking member206according to an alternative embodiment of a vertical support described below has been removed. The lower surface84of the distributor plate38is located at a higher level than the upper surfaces of the wear plates14,16,18. Thus it is possible to turn the distributor plate38on the mounting plate78without removing the wear plates14,16,18.

The flat area68and the sloped surface70together form an unbroken upper surface86of the distributor plate38as indicated inFIG. 6. The distributor plate38shown inFIG. 6is made entirely from white iron. Each vertical side edge50,52,54,56,58,.60has a mounting means in the form a of a hole88as shown inFIG. 6. The hole88may be provided with an inner thread to receive a bolt90forming part of the support72,74and76respectively, as seen inFIG. 7. As is shown inFIG. 7the supports72,74,76are fitted in slots in the lower disc4and bolted to the distributor plate38with the help of the bolts90thus holding the distributor plate38in place.

The mounting of the distributor plate38is performed by lowering it such that the recess82engages the top of the bolt80. The distributor plate38is then turned in the horizontal plane until the side edges50,54and58have the proper position in relation to the wear plates14,16,18. The supports72,74,76are mounted to the distributor plate38such that it becomes fixed to the lower disc4.

After some time of operation of the rotor1the distributor plate38has been subjected to some wear. The wear pattern often has a certain relationship with the outflow openings, such that the maximum wear often occurs at the side edges50,54,58being adjacent to a horizontal wear plate. The supports72,74,76are dismounted. The distributor plate38is now turned horizontally, thus sliding on the upper surface of the mounting plate78, until the side edge52is adjacent to the face62of the wear plate14, the side edge56being adjacent to the face66of the wear plate18and so on. The supports72,74,76are mounted again and the rotor1is ready for operation. Thus it is possible to prolong the life of the distributor plate38by simply turning it 60° in the horizontal plane after some time of operation. At the turning sequence the distributor plate38need not be lifted, since it simple slides on the mounting plate78. The turning thus becomes very quick and easy to perform.

InFIG. 8another embodiment of the invention is shown. The main difference compared to the distributor plate38is that this embodiment is a distributor plate138in the form of an equilateral triangle. The distributor plate138has a central flat area168from which a sloped surface170extends towards the three vertical side edges150,152,154. Each of the three vertical side edges150,152,154is adapted to be located adjacent to a face of a wear plate. The distributor plate138is thus adapted for mounting at a rotor having three outflow openings.

InFIG. 9 to 12an alternative embodiment of the fixing of the distributor plate38is shown. The mounting plate78is provided with a pair of lugs200,202and a round mounting hole204as is better shown inFIG. 11. A vertical support in the form of a locking member206, shown inFIG. 12, is provided with an upper pin208and a lower pin210. The upper pin208fits into the hole88, which need not be threaded, of the distributor plate38and the lower pin210fits into the mounting hole204of the mounting plate78. A spring dowel pin212is inserted via holes214,216in the lugs200,202to lock the locking member206in its proper position. The locking member206thus fixes the distributor plate38to the mounting plate78. The locking member206is easily mounted by just inserting its pins208,210into the hole88and the mounting hole204respectively followed by insertion of the spring dowel pin212such that it locks the locking member206. The above described embodiment provides for very quick mounting or turning of the distributor plate38. Preferably pairs of lugs200,202are located at those sides of the mounting plate78that are located at some distance from a rock passage, such as the rock passage indicated with the arrow A inFIG. 3. Thus the wear on the locking member206is minimized. As indicated inFIG. 9andFIG. 10the upper part of the locking member206is located below the upper surface86of the distributor plate38. Thus the feed material flowing over the upper surface86of the distributor plate38will flow over the locking member206without causing any substantial wear to it.

FIG. 13shows a third embodiment of the invention. A hexagonal distributor plate338shown inFIG. 13has vertical side edges350,352,354and holes388that are similar to the vertical side edges50,52,54and holes88respectively of the distributor plate38described above. The upper surface386of the distributor plate338is flat. The distributor plate338comprises a base layer340made from a flat sheet of a hard steel. A top layer342of a hard metal, such as tungsten carbide, has been coated on the flat upper surface of the base layer340. The distributor plate338having the top layer342made of tungsten carbide has very good resistance to wear and impact and will have a very long life. The flat upper surface of the base layer340makes the tungsten carbide layer342easy to apply to the base layer340. The fact that the upper surface386of the tungsten layer342will be flat as well also contributes to making the application of the tungsten layer342simple. The distributor plate338has a recess (not shown inFIG. 13) which is similar to the recess82of the distributor plate38. The fact that no bolts or holes extend through the upper surface386avoids the formation of any weak spots in the tungsten layer342thus further improving its resistance to wear and impact.

It will be appreciated that numerous modifications of the embodiments described above are possible within the scope of the appended claims.

The number of edges and thus the polygonal shape of the distributor plate may be varied to fit the rotor in question. For a rotor with three outflow openings a distributor with triangular or hexagonal shape is preferably used. A nonagonal shape is also possible. For a rotor with four outflow openings a distributor having square or octagonal shape is preferably used. A dodecagonal shape is also possible. A distributor plate having a number of side edges being two times the number of outflow openings is preferable since the distributor may be turned once for prolonged life. Triangular, square, hexagonal, octagonal, nonagonal and dodecagonal shapes all have the advantage of having only outwardly directed corners. This avoids the swirling of dust loaded air and the subsequent wear that may result from any inwardly directed corners. Further the hexagonal, octagonal and nonagonal shapes have corners with obtuse angles. Obtuse angles have the advantage of providing a distributor plate which is less sensitive to impacting rocks, which may more easily break a corner being right-angled or having an acute angle.

The lower surface84of the distributor plate38may, as described above with reference toFIG. 5, be located above the upper surfaces of the lower wear plates14,16,18. For a rotor with a very low vertical height it may however be necessary, for reasons of maintaining the capacity for material passing through such a rotor, to locate the distributor plate38such that its lower surface84rests directly on the lower disc4of the rotor. In such a case the distributor plate38would need to be lifted somewhat such that its lower surface84comes above the upper surfaces of the wear plates14,16,18before the distributor plate38could be turned.