NZ274266A - Centrifugal mineral breaker with tip assembly attached to rotor using key - Google Patents

Description

New Zealand No. 274266 International No. PCT/NZ94/00106 Priority Date(s): l±}}.ft).?L?...

Complete Specification Filed: Class: 32eaS<. IJ&1&.Q.

Publication Date:^U±.«Jk<\Q!R;..B3^— P.O. Journal No: .'.Brl..7.

NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION Title of Invention: Accessory for mineral breaker Name, address and nationality of applicant(s) as in international application form: SVEDALA NEW ZEALAND LIMITED, a New Zealand company of Mangawhero Road, Matamata 2271, New Zealand 274266 ACCESSORY FOR MINERAL BREAKER technical field This invention relates to an accessory for mineral breakers. background art t t * Reference throughout this specification shall be made to use of the present invention in relation to centrifugal mineral breakers. It should be appreciated however that the principles of the present invention could possibly apply to alternate mineral breakers or any other material or size reduction apparatus.

Centrifugal mineral breakers have mineral material (such as rocks) fed axially into a rotor assembly which is revolving at high speed. Rocks are also fed into the mineral breaker so that they fall in a strerjn outside the rotor assembly. The rocks within the rotor assembly are flung outwardly so that they impact upon the rock stream. This impact shatters the rocks 15 into smaller sizes.

Most of tba parts inside a rotor assembly are adequately protected by wear by a rock lining or wave which builds up within the rotor assembly. m,.

Those areas not protected by rock lining or wave are protected by wear parts. The surfaces located near the discharge ports of the rotor 20 assembly are particularly vulnerable to erosion by the passage of mineral material exiting the rotor assembly.

To address this problem, there are provided tip assemblies located at the discharge ports of the rotor assembly. At these ports, where it is envisaged that there will be the greatest amount of wear on the tip 1 • * assembly, tungsten carbide inserts (or any other hard material) are often inserted. Tungsten carbide is extremely wear resistant, but unfortunately is also very expensive and therefore it is uneconomical to have a tip completely made of this material.

Thus, the material holding the tungsten carbide still wears away (along with the tungsten) and the tip assembly and tip is required to be replaced regularly.

The mineral breaker can suffer serious damage if there is no tip assembly in the proximity of the discharge port. This can happen if the 10 tip assembly wears through or breaks off due to impact or erosion wear. To avoid damage to the rotor in the event that the primary tip is worn or broken for any reason, a backup tip of similar construction may be included in the tip assembly. This backup tip will give some protection to the rotor assembly until the tip can be replaced.

Coarse materials have typically caused premature failure of conventional tip assemblies. This is because the tip assembly is unable to resist the wear and impact of the larger rocks and further unable to retain the larger sized rocks in the rock lining of the rotor.

US Patent No. 4940188 discloses an attempt to address the above problem 20 by providing an increased volume of space behind the tip assembly which allows the rock lining or wave to be more firmly held in place by the tip assembly and to hold larger rocks therein. In some cases, a large rock can overhand the tungsten and provide the wear surface itself. However, there are still problems with this configuration and a greater volume 25 available would also be desirable. 2 3 .3 Further, in order to secure the tip assembly to the rotor assembly, it is necessary for this extra materia! to extend into the rock wave, thus, still taking up some volume which could be used to further retain larger rocks and secure the rock wave.

This prior art assembly also only allows a single mounting system involving bolts to be utilised which again extend into the rock wave. This makes it difficult to access the bolts when it is desired to replace the tip assembly. Excessive wear also occurs at the bolt positions.

The rock wave which builds up within the rotor housing varies according 10 to the type of rock, the size of the rock falling within and the configuration of the rock (say sharp or rounded). Ideally the rock wave which is built up should cover all of the vulnerable parts of the rotor assembly not protected by additional wear parts leaving only the leading edge of the tip (which is mainly tungsten carbide) exposed to the wear of the rock exiting 15 the rotor. Thus this may be true for a certain type of rock entering into the mineral breaker set up a certain way. However, as soon as the rock type is changed, a different rock wave is formed which causes additional wear to the tip than normally encountered.

The applicant has found that by adjusting the angle of the tip holder with 20 respect to the rotor housing, the differing rock waves can be accommodated. Thus, it may be possible to adjust the angle of a tip holder prior to a different type of rock being introduced to the rotor and still accommodate the resultant differing rock wave. Ideally tl\e angle of the tip holder should be that the majority of wear will occur across the face of 25 the tungsten and not the edge. 3 :> Another problem experienced with conventional rotor tip assemblies for centrifugal mineral breakers is slip streaming. Slip streaming is a phenomenon which occurs when water and fine particles of dust and grit from the rocks are accelerated within the rotor and as it exits the rotor 5 assembly. Because of the size of the particles, they find their way into various cracks, small gaps and so forth in the rotor assembly causing considerable wear to the rotor and the tip assemblies. With conventional tip assembly designs, slip streaming wears the ends of the tip assembly as they do not fully meet with the inside surfaces of the top and bottom 10 rotor assembly plates.

It is an object of the present invention to address the above problems or at least to provide the public with a useful choice. , Further objects and advantages of the present invention will become apparent from the following description which is given by way of example 15 only. m Disclosure of I Ck'4:»tCm«JC According to one aspect of the present invention there is provided a key capable of receiving part of a tip assembly for a centrifugal mineral breaker, said key also capable of being inserted into the top or bottom of a 20 rotor assembly for the mineral breaker.

It should be appreciated that in some embodiments the key may form part of the wear parts of the rotor assembly.

According to an alternate aspect of the present invention, there is provided a rotor assembly for a centrifugal mineral breaker capable of 25 receiving a key substantially as described above.

According to another aspect of the present invention there is provided a wear part for a centrifugal mineral breaker capable of receiving a key.

According to yet another embodiment of the present invention there is provided a tip assembly capable of being received into a key substantially 5 as described above.

Reference throughout this specification will be made to material in the form of rocks, grit and so forth. It should be appreciated that these terms are included merely for clarity and can be used interchangeably.

The inclusion of a key into a rotor assembly obviates the need to use bolts 10 to secure the tip assembly to the rotor assembly. This has a number of advantages.

One of the main advantages of the system is that a greater volume is available behind the tip assembly for the rock wave. This allows larger rocks to be retained within the rock wave and for rocks within the rock 15 wave to be held more firmly.

There are farther advantages of using a key as described.

If the key is made removable with respect to the rotor assembly, different keys can be placed into the rotor assembly. These keys may be configured so as to force the tip assembly to be held at different angles depending 20 upon the key being used. Thus, the present invention provides a means by which the angle of the tip assembly can be readily changed. The desired tip angle is one where there is a compromise between rotor peripheral wear and rock buildup. Crushing action in the chamber is also a factor in peripheral wear.

With the present invention, the rock wave can be manipulated as desired.

In the past, feeding rocks into the mineral breaker with different compositions, sizes or configurations could led to rock waves being formed that cause the tip assembly to receive excessive wear as a result of 5 the steel of the tip holder and not the tungsten carbide tip receiving the major impacts and abrasions from the rocks exiting the discharge port of the rotor assembly. Quite commonly, it was the inside face of the tip assembly which would receive these impacts thus causing the tungsten carbide tip to prematurely fall from the tip assembly holder.

The present invention, iallows the tip assembly to be held at different angles so as to produce an optimum exit geometry for any given rock wave for any type of rocks being introduced into the rotor assembly for the mineral breaker.

There are various methods by which the keys in accordance with the 15 present invention can be attached to the rotor assembly.

In one embodiment, the key may slide into a recess or inset inside the top or bottom plate of the rotor assembly or in at least one of the wear parts attached to the rotor assembly. If as envisaged, the inset and the key are of a complementary fit, then this may be ail that is required to hold the 20 key into position during operation of the mineral breaker.

In preferred embodiments the peripheries of the key and inset are such that the key can be slidably fitted into the inset. For example, the key and inset may have complementary curves.

In preferred embodiments however, the key is also bolted to the rotor assembly as it is expected that the centrifugal forces of the rotor could act to force the key out of the inset.

It should be appreciated that the key can be separate to or integral with removable wear plates in the housing.

* According to one aspect of the present invention, there is provided a method of placing a tip assembly into a rotor assembly for a mineral breaker, characterised by the steps of a) placing the tip assembly between two keys, and 10 b) fitting the wholes tip assembly and keys together into the rotor assembly.

There may in some embodiments be provided the additional step of attaching removable bolts to the keys to hold the keys into place.

In some embodiments of the present invention, the tip assembly and the 15 keys may be slid horizontally into the rotor. In other embodiments, the tip assembly keys may be slid vertically into the rotor. For example, there may be provided a hole in the top of the rotor which can accommodate this method.

According to another aspect of the present invention there is provided a 20 method of placing a tip assembly into a rotor assembly for a mineral breaker characterised by the step of passing the tip assembly through an aperture in either the top or bottom plate of the rotor assembly.

In preferred embodiments, the aperture will be in the top plate of the 25 rotor assembly for ease of access, but it should be appreciated that some 7 embodiments of the present invention may have a suitably shaped aperture in the bottom plate as well or as an alternative to an aperture in the top plate of the rotor assembly.

The procedure of fitting the tip assembly using an aperture in the top 5 plate of the rotor assembly may take a variety of forms. For example, the tip assembly may be fitted between the two keys and the whole tip assembly and keys pass through the top aperture. In other embodiments, a key may be fitted into the bottom of the rotor assembly, the tip assembly then slid down through the aperture in the top of the rotor and then the 10 top key fitted. Various permutations of this procedure may also form part of the present invention.

A number of different types of tip assemblies can be used within a key system which forms part of the present invention.

According to one aspect of the present invention there is provided a tip 15 assembly for a rotor to be used in a centrifugal mineral breaker characterised in that the tip assembly can be used with a key as hereinbefore described and the attachment means for the tip assembly is a complementary fit to a rotor extension proximate the discharge port of the rotor.

According to another aspect of the present invention there is provided a rotor extension for a rotor assembly to be used with a centrifugal mineral breaker characterised in the rotor extension is a complementary fit to the tip assembly as described above to be used with the rotor.

The rotor extension may come in a variety of forms. 8 Preferably, the rotor extension is in the form of a backup tip. With the extension in the form of a backup tip, there is provided protection for the rotor if the main tip assembly (hereinafter referred to as the primary tip assembly) breaks off or wears down to the backup tip. This is a preferred 5 embodiment as in addition to providing new advantages, it still incorporates the advantages present in previous tip designs.

Preferably, the backup tips are also removable along with the primary tip assembly.

The complementary fit which forms part of the attachment means may 10 come in a variety of forms. For example, the leading edge of the backup tip may form part of or be a dove tail and the primary tip may have a complementary shaped inset. Thus, the primary tip holder may be slid over the leading edge of the backup tip, this interaction of parts forming the attachment means.

There may be provided alternate complementary fits. For example, the backup tip may have an inset and the primary tip holder may have a protrusion shaped to fit in the inset. It is envisaged however that this embodiment may be impractical as it is desired that the backup tip protrude so the tungsten carbide of the backup tip is readily exposed to the 20 rocks exiting the rotor assembly once the primary tip holder has eroded away.

Other configurations are envisaged. For example, the fit between the primary tip and the backup tip may be in the form of a tongue and groove.

Alternately the rotor extension or backup tip may have a number of 25 grooves or flutes placed therein. The primary tip assembly may have 9 complementary grooves or flutes. Judicious placing of the primary tip assembly into the appropriate grooves or flutes of the backup tip (or rotor extension) can make different shaped tip assemblies which can fit into different shaped keys.

In preferred embodiments however, the complementary fit in the form of a dove tail as the applicant has found this configuration provides a * considerable strength of attachment.

The present invention has a number of advantages over the prior art.

One major advantage of this configuration is that considerably less 10 material is used than in conventional tip constructions. As the primary tip is held at an extension of the rotor (or the backup tip) there is no additional material required to extend into the rock wave and to secure the tip assembly. This enables this configuration to be used with a \ey and thus provides advantages in the management of the rock wave.

An advantage of the complementary fit is that it is not always necessary to replace the backup tip. The remains of the worn primary tip assembly can be slid off from the backup tip and a new primary tip assembly can be easily slid thereon.

According to an alternate aspect of the present invention there is 20 provided a primary rotor tip assembly for a centrifugal mineral breaker characterised in that the tip assembly can be used with key as hereinbefore described, and the attachment means for the tip assembly interlocks with a backup tip.

Although the interlocking means can come in a variety of forms a hook 25 configuration is preferred.

The present invention has a number of advantages over the prior art.

As with the dovetail configuration, one major advantage of the hook or interlocking configuration is that considerably less material is used than in conventional tip constructions which gives all of the advantages as 5 detailed earlier. As the primary tip interlocks with the backup tip there is no additional material required to extend into the rock wave in order to ♦ secure the tip assembly. Instead it can readily be used in conjunction with a key as described previously.

A further advantage of a key arrangement and thus not having the 10 attachment means extending into the rock wave is that the tip assembly can be more readily removed from the rotor assembly. Bolts are not required, which again can make it easier to detach the tip assembly from the rotor.

Yet another advantage of the present invention is that the top and bottom 15 sides of the tip assembly cannot be worn away by slip streaming as they are contained within the keys. That is, there is now no gap between the ends of the tip assembly and the rotor assembly which has been vulnerable to slip streaming.

Thus it can be seen that the present invention offers a number of 20 advantages. Firstly, there is greater volume provided to aid in the securing of the rock wave. Secondly there is provided a relatively easy means by which the angle of the tip assembly can be altered to accommodate the parameters of the rock wave. Thirdly, problems associated with slip streaming have been reduced. 11 wo 95/10359 brief Description of Drawings Further aspects of the present invention will now be described by way of example only and with reference to the accompanying drawing in which: Figure 1 is a diagrammatic perspective view of an attachment means for a tip assembly in accordance with one embodiment of the * present invention, and Figure 2 illustrates an alternate attachment means of the present invention, and Figure 3 is a diagrammatic cross-sectional view of a rotor tip 10 assembly in accordance with one embodiment of the present invention, and Figure 4 is a diagrammatic perspective view of the above tip assembly, and Figure 5 is a diagrammatic cross-sectional view of a tip assembly in 15 accordance with another embodiment of the present invention, and Figure 6 is a perspective view illustrating more clearly the interrelation between the primary tip assembly and the backup tip of the tip assembly illustrated in Figure 5.

BEST MOPES FOB CARRYING OUT THE I! Figure 1 illustrates a number of the parts which, contribute to the attachment of a tip assembly in accordance with one embodiment of the present invention. 12 Part of a rotor assembly is generally indicated by arrow 1. The rotor assembly 1 has a top plate 2 and a bottom plate 3. Two insets 5 and 6 are situated proximate the discharge port generally indicated by arrow 4.

The shape of the insets 5 and 6 are complementary to the external shape 5 of keys 7 and 8. The keyr 7 and 8 are for:r-sided and have a small curved side 9 opposing a larger curved side 10. The opposing curved sides 9 and * and the complementary curved sides in the insets 5 and 6 allow the keys 7 and 8 to be readily slid into position in the rotor assembly 1.

The key 8 has an inset 11. The inset 11 is a complementary fit to one end 10 of the tip assembly 12. There is a further inset (not shown) in the key 7 which is a complementary shape to the other end 13 of the tip assembly 12.

The tip assembly 12 is shown in this embodiment as being a single primary tip with no backup tip. It should be appreciated however that 15 any configuration of tip assembly may be used provided it can be readily fitted into a key as described - refer to Figures 3 to 6.

It should also be readily apparent that the insets 11 of the keys 7 and 8 can be changed to accommodate any cross-sectional shape of a tip assembly 12.

The means by which the keys 7 and 8 attach to the rotor 1 is not illustrated, but in preferred embodiments these are envisaged to be removable bolts.

To place the tip assembly 12 into the rotor assembly 1, -the keys 7 and 8 are first placed on the ends of the tip assembly 12. Then the whole unit is slid 25 horizontally into the insets 5 and 6 of the rotor assembly 1. It can be seen 13 that the curved nature of the sides 9 and 10 of the keys 7 and 8 help guide the unit readily into position.

Figure 2 illustrates an alternate embodiment of the present invention whereby there is an aperture 19 in the top plate 2a of a rotor assembly la. 5 Instead of sliding the tip assembly 12a horizontally into the rotor assembly la, the tip assembly 12a is slid vertically through the aperture * 19 into the rotor assembly la.

A preferred method of attaching the tip assembly 12a to the rotor assembly la, involves the first placing of bottom key 8a into an inset 6a in 10 the bottom plate 3a of the rotor assembly la. Next, the tip assembly 12a pan be slid through the aperture 19 so that bottom end face of the tip assembly 12 a fits into the inset 11a in the key 8a. Next, the top key 7a can be fitted into the aperture 19 in the top plate 2a. This completes the fitting of the tip assembly and. ensures that it is held rigidly into position. It 15 should be noted that this method does not involve the use of any bolts to hold the tip assembly into position.

With reference to Figure 3 there is illustrated a tip assembly generally indicated by arrow 21.

The tip assembly comprises of a primary tip holder 22, and a secondary 20 tip holder or backup tip 23 which is fitted to a rotor housing 24.

The tip holder 22 is positioned in the vicinity of the discharge port, generally indicated by arrow 25, of the rotor 24. A rock wave 27 has built up within the rotor 24 in front of the tap holder 22. Once the rock wave 27 has built up, rocks pass through the discharge port 25 over the tip 25 holder 22. 14 The tip holder 22 comprises a tungsten carbide tip 26 held within tempered steel 28 (or any similar material). The angle at which the tungsten carbide tip 26 is positioned with respect to the rock wave 27 and the discharge port 25 is such that the leading edge 29 of the tip 26 5 encounters most of the wear caused by the exit of rocks through the discharge port 25.

* The means by which the tip holder 22 is attached to the rotor 24 is via a dove tail arrangement 30 with the backup tip 23. In this embodiment, the tip holder 22 has an insert which is complementary to a protrusion on the 10 backup tip 23.

Referring specifically to Figure 4, it can be seen that the length of the tip assembly is such that a dove tail attachment means 30 can provide a secure attachment which is unlikely to break off. It can also be seen that this embodiment can fit readily into a key arrangement With respect to Figures 5 and 6, there is illustrated a tip assembly generally indicated by arrow 41.

The tip assembly 41 includes a primary tip assembly 42. The primary tip assembly 42 is comprised of a tip holder 43 which holds a tungsten carbide tip 44.

The tip assembly 42 is positioned proximate a discharge port of a rotor assembly (not shown) for a centrifugal mineral breaker. The angle at which the tip assembly 42 is positioned ensures that the wear resistant tungsten carbide tip 44 receives the majority of the impacts from rocks exiting the rotor housing.

Situated under the primary tip assembly 42 is a secondary tip assembly or backup tip 45. Like the primary tip at iembly 42, the backup tip 45 also has a tungsten carbide tip 46.

In the above embodiment, the tungsten carbide tip 46 is not situated in the 5 centre of the backup tip (as with conventional backup tips) but at the outside face thereof. However, it can be seen that the leading edge of the tip 46 will still be exposed to rocks exiting the discharge port if the primary tip assembly 42 is worn down or breaks off.

The primary tip assembly 42 and the backup tip 45 are attached to each 10 other by an interlocking means in the shape of a hook configuration generally indicated by arrow 47. So as to illustrate this hook configuration clearly, the outlines of the primary tip 42 and the backup tip 45 are represented differently.

Figure 6 illustrates more clearly the interlocking relationship between 15 the primaxy tip 42 and the backup tip 45. It can be seen that what appears to be a hook configuration from the side is actually a very secure interlocking arrangement with at least part of both of the backup tip 45 and the tip assembly 42 configured to come around and over each other.

The tip assembly 42 and the backup tip 45 connect to the rotor assembly by 20 a key as described previously.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto -without departing from the scope thereof as defined in the appended claims. 16

Claims (1)

1. the claims Defining thej r Are; 274266 A centrifugal mineral breaker which includes a rotor tip and rotor assembly, the centrifugal mineral breaker characterised in that the rotor tip assembly is connected to the rotor assembly by a key. A centrifugal mineral breaker as claimed in claim 1 wherein the key forms part of the wear plate of the rotor assembly when the key is in use. A centrifugal mineral breaker as claimed in either claim 1 or claim 2 wherein the key is removable form the rotor assembly. A centrifugal mineral breaker as claimed in any of claims 1 to 3 wherein the key can slide into an inset inside the tip or bottom plate of the rotor assembly. A centrifugal mineral breaker as claimed in any one of claims 1 to 3 wherein the key can slide into an inset in at least one of the wear parts attached to the rotor assembly. A centrifugal mineral breaker as claimed in either claim 4 or claim 5 wherein the key and inset are of complementary fit. A centrifugal mineral breaker as claimed in any one of claims 1 to 6 wherein the key is bolted to the rotor assembly. A method of placing a tip assembly into a rotor assembly for a mineral breaker as claimed in claim 1 characterised fay the steps of: a) placing the tip assembly between two keys, b) fitting the whole tip assembly and keys to{ assembly. 17 274266 > 9. ^ 10. 1L 12. 13. 14. 16. 17. A method as claimed in claim 8 characterised by the further step of attaching removable bolts to the keys to hold the keys into place. A rotor assembly for a centrifugal mineral breaker as claimed in claim 1 adapted to receive a key. A wear part for a centrifugal mineral breaker as claimed in claim 1, adapted to receive a key. A tip assembly for a centrifugal mineral breaker as claimed in claim 1, wherein the tip assembly is adapted to receive a key. A tip assembly as claimed in claim 12 characterised in that the attachment means by which the tip assembly attaches to the rotor is a complementary fit to a rotor extension proximate the discharge port of the rotor. A tip assembly as claimed in claim 13 wherein the rotor extension is in the form of a back up tip. A tip assembly as claimed in claim 14 wherein the back up tip is removable along with the tip assembly. A tip assembly as claimed in any one of claims 13 to 15 wherein the complementary fit which forms part of the attachment means is in the form of a dove tail. A tip assembly as claimed in any one of claims 13 to 15 wherein the rotor extension has a number of grooves or flutes in same. A rotor extension for a centrifugal mineral breaker, th'e rotor extension being a complementary fit to a tip assembly as < 18 *74266 ) 19. 2L o 22. 23. 24. 27. 28. A tip assembly as claimed in claim 12 characterised in that the attachment means for the rotor tip assembly interlocks with a backup tip. A tip assembly as claimed in claim 19 wherein the tip assembly interlocks with the backup tip by the means of a hook configuration. A tip assembly as claimed in either claim 19 or claim 20 wherein the tip assembly interlocks with the backup tip in such a manner that at least part of both of the backup tip and the tip assembly are configured to come around and over each other. A backup tip capable of interlocking with a primary tip assembly as claimed in any one of claims 20 to 21. A key substantially as herein described with reference to and as illustrated by the accompanying drawings. A method of placing a tip assembly into a rotor assembly for a centrifugal mineral breaker substantially as herein described with reference to and as illustrated by the accompanying drawings. A rotor assembly substantially as herein described with reference to and is illustrated by the accompanying drawings. A wear part substantially as herein described with reference to and as illustrated by the accompanying drawings. A tip assembly substantially as herein described with reference to and as illustrated by the accompanying drawings. A backup tip substantially as herein described with reference to and as illustrated by the accompanying drawings. END 0¥ CL&IMS 19