TECHNICAL FIELD

The invention relates to improvements in vertical shaft impact crushers. The invention has particular application to the replacement of the wear parts of a rotor for a vertical shaft impact rock crusher.

BACKGROUND ART

A Vertical Shaft Impact (VSI) crusher is a particular type of crusher that is used in the production of aggregate. A VSI crusher includes a rotor configured to rotate within a crushing chamber at high speeds about a vertical axis. Rock material enters the rotor by an inlet port and, as the rotor spins, is ejected from the rotor via outlet ports arranged about the circumference of the rotor and is hurled against anvils placed strategically about the chamber or the rock lined shell of the crusher chamber. The impact forces breaks down the ejected rock material into aggregate. A crusher which uses this mode of breaking down rock material is sometimes known as a "rock on rock" crusher.

Some VSI crushers create impact forces by ejecting rock material from the rotor into a cascade of rock material that falls past the outlet ports of the rotor. An example of such a crusher is described in New Zealand Patent No. 297910.

Regardless of the mode of action of the rock crusher, the rotor body and its constituent components are exposed to considerable wear and tear due to the impact of the rock material entering the rotor, and the speeds at which the rotor operates. A conventional VSI rotor consists of a one piece steel fabricated rotor body. The body includes an inlet port, outlet ports, a base plate and a top plate. The various outlet ports are formed by bolting or welding vertical members between the base and top plates. The rotor body is then protected by a number of wear resistant castings fixed about the rotor using a variety of methods.

It is not uncommon to have over 40 wear resistant components, or wear parts, protecting the rotor body. Many of these are what are referred to in the industry as rotor tips. The rotor tips are often placed at the exit of the outlet ports of the rotor body. It is usually these wear parts which experience the greatest wear and tear. Such wear parts are typically attached to the rotor through the use of bolts or similar fasteners. These fasteners are often subject to wear and tear, and can become hard to remove. This can prolong the time the rotor is offline for maintenance.

For particularly difficult fasteners, it may be necessary to use cutting tools to allow the wear parts to be replaced. This introduces additional health and safety risks for the person using the cutting tool. This can also add to the time required for maintenance of the rotor.

In order to replace the rotor tips or cavity wear plates, it is often necessary to partially dissemble the rotor body by removing other rotor wear parts. This is a cumbersome and time consuming task. Despite the provision of doors on the crushing chamber, it is usually still necessary to remove the roof of the crusher in order to gain access to the rotor body and allow the disassembly of the rotor body.

In order to achieve the necessary maintenance of the crusher, it must be shut down. VSI crushers are significant items of machinery, processing large amounts of rock material. The rotor body is engineered accordingly and consequently is not insignificant purchases for their operators. Furthermore, the running costs of such VSI crushers can be particularly significant. Because of the expenditure associated with the purchase of crushers, and their running costs, operators tend to maximise their use where possible.

Thus, it is undesirable to have a VSI crusher offline for extended periods of time in order to fulfill maintenance requirements. The downtime of a crusher can have an impact on the throughput of the facility in which the crusher is installed. If the VSI crusher does need to be offline, then the downtime should be preferably kept to a minimum.

Furthermore, significant disassembly of the rotor often requires several persons and heavy lifting equipment in order to remove the roof and possibly other components of the crusher. This is not ideal and is not conducive to keeping maintenance costs to a minimum.

VSI crushers are also used in mineral material processing plants, such as mobile crushing plants, which combine the crusher with a feeding device, such as a conveyor or hopper, on a heavy vehicle. When replacing wear parts on these crushers, not only does the rotor body of the crusher have to partially disassembled but it is often necessary to remove the surrounding ancillary equipment as well. This extends the overall time required to replace the wear part.

It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications may be referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country. It is acknowledged that the term 'comprise' may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term 'comprise' shall have an inclusive meaning - i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term 'comprised' or 'comprising' is used in relation to one or more steps in a method or process.

DISCLOSURE OF THE INVENTION

According to another aspect of the present invention, there is provided a rock crusher, the crusher including a rotor, wherein the rotor includes: a plurality of wear parts, a mounting bar for the wear parts, a top plate, wherein the top plate has an upper surface and a lower surface, and includes an aperture for the mounting bar, the aperture passing between the upper surface and the lower surface, characterised in that the mounting bar includes a head, shaft and a foot, and wherein the head is configured with a lateral protrusion extending from a side of the head to engage with a tapered or stepped portion of the aperture passing between the upper surface of the top plate to its lower surface, the protrusion being dimensioned such that it is larger than the cross- sectional area of the shaft of the mounting bar. According to another aspect of the present invention, there is provided a rotor for a rock crusher, wherein the rotor includes: a plurality of wear parts, a mounting bar for the wear parts, a top plate, wherein the top plate has an upper surface and a lower surface, and includes an aperture for the mounting bar, the aperture passing between the top surface and the bottom surface, characterised in that the mounting bar includes a head, shaft and a foot, and wherein the head is configured with a lateral protrusion extending from a side of the head to engage with a tapered or stepped portion of the aperture passing between the upper surface of the top plate to its lower surface, the protrusion being dimensioned such that it is larger than the cross- sectional area of the shaft of the mounting bar.

According to another aspect of the present invention, there is provided a mounting bar for a wear part for a rotor of a rock crusher, wherein the rotor includes a top plate, wherein the top plate has an upper surface and a lower surface, and includes an aperture for the mounting bar, the aperture passing between the upper surface and the lower surface, and a base plate, wherein the mounting bar includes: a shaft configured to receive a wear part, a head, and a foot configured to engage with the base plate of the rotor, the mounting bar characterised in that the head is configured with a lateral protrusion extending from a side of the head to engage with a tapered or stepped portion of the aperture passing between the upper surface of the top plate to its lower surface, the protrusion being dimensioned such that it is larger than the cross-sectional area of the shaft of the mounting bar. Accordingly to another aspect of the present invention, there is provided a wear part assembly for a rotor of a rock crusher, wherein the rotor includes a top plate, wherein the top plate has an upper surface and a lower surface, and includes an aperture for the mounting bar, the aperture passing between the upper surface and the lower surface, and a base plate, wherein the assembly includes: a mounting bar configured to receive at least one wear part, and at least one wear part, the assembly characterised in that the mounting bar is configured with a head, shaft and a foot, and wherein the head is configured with a lateral protrusion extending from a side of the head to engage with a tapered or stepped portion of the aperture passing between the upper surface of the top plate to its lower surface, the protrusion being dimensioned such that it is larger than the cross-sectional area of the shaft of the mounting bar.

According to yet another aspect of the present invention there is provided a mineral material processing plant, wherein the plant includes a rock crusher including a rotor substantially as described above.

According to another aspect of the present invention, there is provided a method of installing a mounting bar into a rotor of a rock crusher, wherein the rotor includes: a top plate, wherein the top plate has an upper surface and a lower surface and includes an aperture for a mounting bar, the aperture passing between the upper surface and the lower surface, and a base plate, and wherein the mounting bar includes a shaft configured to receive a wear part, a head, and a foot configured to engage with the base plate of the rotor, and wherein the head is configured with a lateral protrusion extending from a side of the head to engage with a tapered or stepped portion of the aperture passing between the upper surface of the top plate to its lower surface, the protrusion being dimensioned such that it is larger than the cross- sectional area of the shaft of the mounting bar, wherein the method includes the steps of: a) tilting the mounting bar away from a vertical orientation such that the protrusion has a smaller cross-sectional area than the aperture of the top plate; and b) passing the head of the mounting bar through the aperture from the lower side of the top plate; and c) returning the mounting bar to a vertical orientation such that the protrusion has a substantially equal or greater cross-sectional area than the aperture and lowering the mounting bar such that the head of the mounting bar engages with the top plate.

The present invention provides apparatus and a method for the replacement of wear parts of a rotor body for a rock crusher.

The invention has particular application to a type of rock crusher known as a vertical shaft impact (VSI) crusher. However, persons skilled in the art will appreciate that with suitable modifications, the present invention may be used in other types of rock crushers, such as a horizontal shaft impact rock crusher.

A VSI crusher has a rotor body which spins at high speed within a crushing chamber. A rotor body should be understood to mean the part of the rotor which rotates at high speeds and includes at least an inlet port for rock material to enter the rotor and outlet ports through which the rock material is ejected.

The crushing chamber of most VSI crushers is provided with a gate or door which allows access to the rotor body. The rotor body includes a top plate and a base plate which sandwich the vertically standing walls of the rotor. The wear parts are secured to the walls of the rotor.

In a typical VSI crusher, the top plate includes the inlet port for rock material, the port being situated at the centre of the plate. This allows a gravity feed of rock material into the rotor.

The outlet port should be understood to mean the port by which rock material exits the rotor into the crushing chamber. In typical VSI crushers, the rotor has two or more outlet ports, situated around the circumference of the rotor. The outlet ports are usually defined at least partially by the walls of the rotor and by the top and base plates. Wear parts should be understood to mean the sacrificial components of the rotor that absorb the impact of rock material as it passes through the outlet ports, assisting in the breakdown of the rock material into aggregate.

Reference shall now be made throughout the remainder of this specification to the wear parts being rotor tips, although this is not meant to be limiting. The present invention may be readily implemented with other types of wear parts, depending on their configuration and placement.

The rotor tips can also be used to retain a rock lining against the impact surfaces of the outlet port.

A rock lining should be understood to mean a lining or coating of rock material along at least a portion of the outlet walls which absorbs the impact of rock material entering and exiting the rotor body. It should be understood that rotor tip holders are used in most crushers to hold the rotor tips in a fixed position. Reference shall now be made throughout the remainder of this specification to a rotor tip holder being a mounting bar.

The mounting bar is an elongate structure, configured with a head, a foot and a shaft. The length of the mounting bar is slightly longer than the distance between the top and base plates of the rotor body.

Typically the mounting bar will be configured from a suitably hard wearing and impact resistant material, such as Ni-Hard or Hi-Chrome (iron/chrome alloys), tungsten carbide or the like. The head should be understood to engage with the top plate of the rotor body, while the foot should be understood to engage with the base plate of the rotor body.

The shaft should be understood to be the portion of the mounting bar that connects or otherwise links the head and foot. In preferred embodiments of the present invention, the shaft forms the main body of the mounting bar. The head includes a lateral protrusion from at least one side of the head. In preferred embodiments of the present invention the protrusion may extend from two sides of the head. In such embodiments, preferably, the protrusions extend from opposite sides of the head.

The extent of the protrusion of the head may vary depending on the requirements of the operator, but it must sufficient such that the head of the mounting bar has a larger cross-sectional area in a plan (top) view than the shaft and foot of the mounting bar.

The head engages with at least part of the top plate (the upper surface is the surface of the top plate facing away from the base plate while the lower surface of the top plate is the surface that faces the base plate). The top plate includes an aperture running from its upper surface to its lower surface. In preferred embodiments of the present invention, the aperture is dimensioned to be substantially equal to or greater than the cross-sectional area of the head of the mounting bar. This is an important consideration of the present invention.

Because the length of the mounting bar is greater than the distance between the top and base plates of the rotor, when placing the mounting bar into the rotor body from the side i.e. through the door of the crushing chamber, the mounting bar must be tilted away from the vertical. This reduces the footprint of the head of the mounting bar to less than the cross-sectional area of the aperture in the top plate. The head can then pass through the aperture. Once this is done, the mounting bar can be returned to the vertical and lowered. The size of the footprint of the head of the mounting bar, and the length of the mounting bar, prevents it from passing back through the aperture, and the head engages with the top plate.

In some embodiments of the present invention, the aperture in the top plate is tapered or stepped from the upper surface to its lower surface, such that the under side of the protrusion of the head contacts the upper surface of the top plate.

In preferred embodiments of the present invention, the dimensions of the aperture are largely complementary to that of the head of the mounting bar in its vertical (upright) position, holding the mounting bar in position.

Thus, the top surface of the head of the mounting bar may sit flush with the top plate. This allows ancillary equipment to be freely positioned or otherwise secured to the top plate of the rotor body.

Persons skilled in the art will appreciate that the engagement of the head of the mounting bar with the top plate effectively holds or suspends the mounting bar (and any rotor tips carried by the mounting bar). In preferred embodiments of the present invention, the cross-sectional area of the foot of the mounting bar is less than that of the head. This is so that there is sufficient clearance for the tilting movement of the mounting bar during installation and removal.

However, it is not beyond the scope of the present invention that the foot has a cross- sectional area approximating that of the head. The advantage of this is that it does not matter which end of the mounting bar engages with the top and base plates.

The base plate may include a recess or aperture which is substantially in vertical alignment with the aperture of the top plate. In preferred embodiments of the present invention, the size of the recess or aperture approximates the cross-section area of the foot of the mounting bar.

Therefore, when the mounting bar is lowered during its installation, its foot engages with the recess (or aperture) of the base plate. This provides additional stability for the mounting bar, but without the need for fastening devices.

In some embodiments of the present invention, the portion of the base plate adjacent includes a channel or groove which gradually deepens as it approaches the recess. This may be useful in providing additional clearance for the movement of the mounting bar as it is tilted into and out of position. However, it will be appreciated that this channel is positioned such that it is out of the direct path of the outlet ports of the rotor.

In preferred embodiments of the present invention, the recess or aperture may be of sufficient depth such that the foot sits flush with the base plate.

In preferred embodiments of the present invention, the foot of the mounting bar may also be configured with a lip or protrusion that may sit on the upper surface of the base plate (which faces the lower surface of the top plate). This helps with locating and maintaining the position of the assembly. This protrusion is positioned to ensure that it faces away from the direction from which rock material contacts the tips. The foot may be configured to provide a support surface for the rotor tips. This makes it easier to add the rotor tips to the mounting bar, as the lower tip can rest on the upper surface of the foot protrusion while being fixed in place with a fastener. The next tip can then be positioned on top of the first, resting on that while being fixed in place. However, it will be appreciated that size constraints may placed upon the dimensions of the foot protrusion as should it extend too far away from the shaft, it may inhibit the tilting movement that is required to install the mounting bar into the rotor body.

Furthermore, in some embodiments of the present invention, rather than engaging the mounting bar with the rotor body through the crusher compartment inspection door, it may be desirable to install the mounting bar from above by removing the roof of the crusher and passing the mounting bar through the aperture in the top plate. An excessively dimensioned foot protrusion such that it was larger than the head, and therefore the aperture in the top plate, would inhibit this.

By suspending or holding the mounting bar by its engagement at its head with the top plate, and securing its foot within the base plate, the mounting bar is generally held in position by its own weight, and without the use of fasteners. Centrifugal forces that are applied to the mounting bar as the rotor body is spinning at high speeds also assist in ensuring the mounting bar remains in position during operation of the crusher.

The mounting bar can be put into place through the door of the crushing chamber. This is a significant advantage over prior art arrangements. There is no need to remove the roof of the crusher or the top plate. The mounting bar can simply be assembled with the rotor tips and then put into position.

Conversely, the mounting bar can be removed from the rotor body, simply by lifting it vertically, tilting it to allow the head of the mounting bar to pass through the top plate and extracting it from the crusher. The rotor tip, or rotor tip segment, can then be replaced and the mounting bar re-installed (or replaced with a pre-assembled mounting bar). This minimizes the downtime of the crusher.

The shaft is configured to receive at least one rotor tip. It will be appreciated that this can be achieved in a number of ways.

In one embodiment of the invention, the shaft is configured with a recess or channel running one side (which can be thought of as the contact side of the mounting bar) of its length, the channel being complementary to at least part of the profile of a rotor tip. The bottom of the recess is provided with fastener apertures passing through to the non contact side of the mounting bar (which will generally face away from the path of rock material as it is ejected from the rotor).

The rotor tip is inserted into the recess, and secured in place with fasteners such as bolts or the like.

In preferred embodiments of the present invention, the rotor tips are segments, which may be assembled to form a wear part assembly.

In most VSI crushers, rotor tips are formed by segments of a suitable hardened material, such as tungsten carbide. The advantage of using segmented rotor tips is that some portions of the tip will experience higher wear than others. The centre segment of the tip usually wears down first, which those closest to the head and foot usually will have a longer working life. Thus, the wear rates of individual segments can be improved by moving them to different positions on the mounting bar.

Accordingly, the number of rotor tip segements (and therefore fastening apertures) that can be carried by the mounting bar may vary depending on the requirements of the operator.

The crusher incorporating the present invention may be used as a stand alone crusher or alternatively, may be incorporated into a stationary or mobile mineral material processing plant. A mobile mineral material processing plant should be understood to mean a heavy vehicle to which a crusher and ancillary equipment such as feed and discharge conveyors may be mounted.

The present invention offers a number of advantages over the prior art, including:

• easy replacement of wear parts through the inspection door of the crushing chamber of a VSI crusher;

• facilitates easier maintenance of the rotor body if required;

• shortens the time in which a rotor must be offline in order to carry out maintenance;

• at the very least, the invention offers the public with a useful choice. BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of the present invention will become apparent from the ensuing description which is given by way of example only and with reference to the accompanying drawings in which:

Figure 1 is a perspective view of one embodiment of the present invention;

Figure 2 is a second perspective view of the embodiment illustrated in Figure 1 ;

Figures 3a-b is a perspective view of the embodiment of the invention, as illustrated in

Figures 1 and 2, in use with a rotor body; Figure 4 is a side view of a crusher including the rotor body of the present invention; and

Figure 5 is a side view of a mobile mineral processing plant. BEST MODES FOR CARRYING OUT THE INVENTION

One embodiment of the invention is depicted in Figure 1 and includes a mounting bar (generally indicated by arrow 1 ), which in use, will be sandwiched between the top and base plates of the rotor body (not shown). The mounting bar (1 ) includes a shaft (2), a head (3) and a foot (4). The foot (4) includes a lateral protrusion (5) which is dimensioned to provide a surface onto which the rotor tips (6) may be placed.

It will be seen that the rotor tips are segmented, with each segment (6) provided with fastener apertures (7). It should be appreciated that because of a lateral protrusion (8), the cross-sectional area of the head is greater than that of the shaft (2) of the mounting bar (1 ).

In this embodiment of the mounting bar, the head (3) has a second protrusion (9) on the opposing side of the mounting bar (1 ) to the first protrusion (8). Similar, the foot has a second smaller protrusion (10) opposing the first (5) It will be seen that the reverse or non-contact side (1 1 ) of the shaft (2) of the mounting bar (3) is provided with a number of fastening apertures (12). Bolts (13) or the like can pass through the shaft (1 ) into the rotor tips (6), securing them to the mounting bar (1 ).

In Figure 2, the shaft (3) of the mounting bar (1 ) is formed with a recess (14) along its length. This recess is configured to receive a portion (15) of the segmented rotor tips (6) which is complementary to the recess (14).

In use as shown in Figure 3a, the mounting bar (1 ), together with its rotor tips (6), forms a wear part assembly (generally indicated by arrow 16), which can be positioned and secured to the rotor (17) through the door (not shown) of the VSI crusher (not shown). By tilting (arrow 18) the mounting bar (1 ) away from the vertical, thus reducing the foot print of the head (3) of the mounting bar (1 ), it can be passed through a suitably sized aperture (19) in the top plate (20) of the rotor (17).

The head (3) of the mounting bar (1 ) includes protrusions (8, 9) extending laterally away from the shaft (2). These protrusions co-operate with the aperture (19) of the top plate (20).

The orientation of the mounting bar (1 ) can be returned to the vertical (arrow 21 ), as shown in Figure 3b, and the foot (4) of the mounting bar (1 ) inserted into a suitable recess (22) in the base plate (23) of the rotor (17). The foot includes a protrusion (10) extending outwards from the shaft, and this assists in the locating of the wear part assembly (16). This protrusion (10) faces away from the rotor tips (6).

Thus, this embodiment of the invention can be inserted into the rotor (17) through the inspection door of the crushing compartment (not shown), and without requiring fastening parts to fix the mounting bar (1 ) to the rotor (17). This is a significant advantage over the prior art.

Furthermore, the replacement of the rotor tips (6) can be achieved without removing the roof of the crusher (not shown) to gain access to the rotor. Instead, the door to the crushing chamber (not shown) can be opened, and the mounting bar (1 ) removed by hand and replaced with an assembled mounting bar with wear parts already fitted. Turning now to figure 4, this depicts a crusher (23) which includes the rotor body (17) housed within a frame (24). The crusher (23) is driven by a motor (25) mounted to a frame (26). Both the motor (25) and the rotor shaft (26) are provided with pulleys (27).

Rock material (not shown) enters the crusher (23) via a feeder hopper (28) mounted to the roof (29) of the crusher (23). Figure 5 shows the crusher (23) as part of a mobile mineral processing plant (30). The plant (30) includes a feeding device (31 ) to conduct rock material (not shown) to the feeder hopper (28) of the crusher (23). As the rock material is processed, it exits the plant (30) via a discharge conveyor (32).

The plant (30), mounted to a tracked propelling means (33), is operable via a control unit (34) which controls the crusher (23) and its ancillary equipment such as the feeding device (31 ). It should be appreciated that instead of, or in addition to, tracks the plant (30) may include wheels, runners or legs.

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.