Field of invention

The present invention relates to a jaw crusher and in particular, although not exclusively, to a wedge block forming part of a wedge block assembly for controlling the crushing gap between opposed jaws of a jaw crusher, the wedge block and/or wedge block assembly having a wear region to inhibit wear of the wedge block due to sliding movement against other components of the wedge block assembly and/or the jaw crusher. Background art

Jaw crusher units typically comprise a fixed jaw and a movable jaw that define a crushing zone therebetween and a drive mechanism operative to rock the movable jaw back and forth in order to crush material in the crushing zone.

The crushing zone defined between the fixed jaw and the movable jaw is generally convergent towards its lower discharge end so that crushable material fed to the upper and wider end of the zone is then capable of falling downward under gravity whilst being subject to repeated cycles of crushing movement in response to the cyclical motion of the movable jaw. The crushed material is then discharged under gravity through the narrower lower discharge end onto a conveyor belt for onward processing or final discharge from the crusher unit to a suitable stock pile.

Commonly, the frame that supports the fixed jaw is referred to as the front frame end. The moveable jaw is connected to what is typically referred to as a back frame end via a mechanically actuated link mechanism that serves to control and stabilise the oscillating movement of the moveable jaw relative to the stationary jaw. Typically, the link mechanism is both statically and dynamically linearly adjustable to control the grade or size of the resultant crushed material, to facilitate absorption of the impact forces generated by the crushing action and to expand or open the crushing zone to prevent damage to the crusher in the event of non-crushable material being accidentally introduced into the crushing zone.

One type of jaw crusher that has emerged as particularly advantageous for both manual and automatic adjustment of the crushing gap between the opposed jaws is that configured with a hydraulic wedge system. Two opposed hydraulically actuated wedges slide in touching contact relative to one another to control the position of the lower portion of the swing jaw and hence the crushing and discharge gap at the lower region of the crushing zone.

Example jaw crushers with gap adjustment mechanisms are disclosed in EP 0822006; JP 2005-013918; JP 2006-247602 and EP 2135677. However, due to the substantial loading forces transmitted through the generally triangular shaped wedges, there respective contact surfaces are subject to accelerated wear and seizing. Seizing of the wedges may in turn result in significant damage to the other components of the jaw crusher. There is therefore a need for a jaw crusher and in particular a wedge block and wedge block assembly that addresses the above problem. Summary of the Invention

Accordingly, one object of the present invention is to provide a jaw crusher and a wedge block and assembly that exhibits both wear resistance and resistance to seizing during use and in particular sliding contact of the wedge block with other components of the assembly and/or jaw crusher components. The objective is achieved via a wear region positioned or positionable at the contact surface of the block intended for sliding contact with for example a second block of the wedge assembly. Where the wedge blocks are generally triangular shaped, the wear region is positioned intermediate between the opposed hypotenuse contact surfaces.

According to one aspect, the wedge block may comprise a hardened external surface with the hardening created by chemical processing steps typically referred to as 'case hardening'. Reference to 'case hardening' within the specification refers to a process of infusing, dissolving and/or implanting chemical species within an outer layer region of the wedge block. The infused chemical species react with this outer region to create a layered structure, chemically distinct from the inner untreated wedge block core, that exhibits increased hardness and fatigue strength. According to a further aspect, the wear region may be provided by a non-integral/separate wear part that sits between the opposed contact surfaces of the wedge blocks (or the contact surfaces between the wedge block and another component of the jaw crusher, such as a region of the back frame end or toggle plate bushing). The wear part may be secured to the wedge block so as to move with the block as a unitary component.

Accordingly, the present invention is less susceptible to seizing during use as the sliding contact surfaces are resistant to deformation that would otherwise increase friction during sliding.

According to a first aspect of the present invention there is provided a wedge block to form part of a wedge block assembly for controlling a separation distance of an opposed pair of jaws of a jaw crusher, the wedge block comprising: a first contact surface configured to slide against an opposed contact surface of a further component of the wedge block assembly and/or the jaw crusher; characterised by: a wear region positioned or positionable at an interface of the first contact surface and the opposed contact surface, the wear region being chemically, mechanically and/or physically distinct from a core region of the wedge block and configured to inhibit wear of the first contact surface of the wedge block due to sliding movement against the opposed contact surface.

Reference to 'chemically, mechanically and/or physically distinct' within the specification encompasses a chemically altered region or a region of different material to a core or untreated region of the wedge block. The chemical alteration and/or the different material provides different mechanical and/or physical properties at the wear region relative to the wedge core (or an untreated surface region of the wedge block) that typically comprises a metal and in particular steel.

Optionally, the wear region is non-integral to the wedge block and comprises a wear part to sit between the first contact surface and the opposed contact surface. Preferably, the wear part comprises a plate-like body comprising any one or a combination of the following set of: a metal and organic and/or inorganic composite; a fibre based material; an organic based metal composite; a ceramic material. Optionally, the plate-like body comprises: steel wool; wire; copper; iron; graphite; a filler material; and/or a friction modifier in the case of the inorganic composite; glass; rubber; carbon; a para-aramid; a filler material; and/or a friction modifier in the case of the fibre base material; steel; copper; a filler material; and/or a friction modifier in the case of the organic based metal composite;

ceramic fibres; metal fibres or particles; a filler material; and/or a friction modifier in the case of the ceramic material. Optionally, where the plate-like body comprises a metal and organic and/or inorganic composite, the plate-like body further comprises 20 to 80% by weight of a metal. Optionally, where the plate-like body comprises an organic based metal composite, the plate-like body comprises 1 to 40% by weight of a metal.

Where the wear part is non-integral to the wedge block, the plate-like body may be mechanically attached to the wedge block so as to extend over at least a portion of the first contact surface. Optionally, the wear part is mechanically attached to the wedge block by screws counter- sunk into the wedge block such that they do not protrude beyond a plane of the contact surface of the wear part. Optionally, the wear part is secured to the wedge block by bonding via an adhesive. Alternatively, the wear part may be clipped in position via interconnecting male and female portions. Alternatively, the wear part may be attached via interconnecting friction fitting components.

Optionally, the wear region is integral to the wedge block and comprises an outer region of the wedge block that is hardened and comprises a higher concentration of: elemental carbon, boron, and/or nitrogen; and/or carbon, boron and/or nitrogen based compounds; and/or metal oxides; relative to an inner region of the wedge block.

Optionally, the outer region comprises at least one boundary layer comprising nitrogen and/or nitride compounds. In one aspect of the present invention, the boundary layer comprises a plurality of sub-layers comprising: a diffusion layer positioned at an innermost region of the boundary layer closest to the underlying wedge block, the diffusion layer comprising dissolved nitrogen and/or nitride precipitations; a passive layer positioned at an outermost region of the boundary layer to be external facing relative to the underlying wedge block, the passive layer comprising iron oxide; and a compound layer positioned intermediate between the diffusion and the passive layers, the compound layer comprising a carbonitride.

According to a second aspect of the present invention there is provided a wedge block to form part of a wedge block assembly for controlling a separation distance of an opposed pair of jaws of a jaw crusher, the wedge block comprising: a first contact surface configured to slide against an opposed contact surface of a further component of the wedge block assembly and/or the jaw crusher; characterised by: a wear region formed as a boundary layer at the first contact surface, the boundary layer formed by a process of infusing carbon, nitrogen and/or boron into the first contact surface to form the boundary layer exhibiting increased hardness relative to an inner region of the wedge block and/or a region that has not been subject to said process.

According to a third aspect of the present invention there is provided a wedge block assembly for controlling a separation distance of an opposed pair of jaws of a jaw crusher, the wedge block assembly comprising: a first wedge block as described herein; a second wedge block as described herein; a first contact surfaces of the first and second wedge blocks positioned or positionable in opposed contact and a wear region positioned at and/or between the opposed first contact surfaces.

Optionally, substantially all of the outer surface of the first and second wedge blocks comprise at least one boundary layer comprising a higher concentration of: elemental carbon, boron, and/or nitrogen; and/or carbon, boron and/or nitrogen based compounds; and/or metal oxides; relative to an inner core region of the respective first and second wedge blocks.

Preferably, the first and second wedge blocks each comprise a wear region formed by a process of case hardening at least a portion of the first contact surfaces of the first and second wedge blocks. Alternatively or in addition, the wear region is positioned at the interface between the opposed first contact surfaces of the first and second wedge blocks wherein the wear region comprises a non-integral wear part.

According to a fourth aspect of the present invention there is provided a method of manufacturing a wedge block to form part of a wedge block assembly for controlling a separation distance of an opposed pair of jaws of a jaw crusher, the method comprising: case hardening at least a first contact surface of the wedge block to provide a wear region, the first contact surface configured to slide against an opposed contact surface of a further component of the wedge block assembly and/or the jaw crusher wherein the wear region is chemically, mechanically and/or physically distinct from a core region of the wedge block.

According to a fifth aspect of the present invention there is provided a jaw crusher comprising a wedge block assembly as described herein.

Brief description of drawings

A specific implementation of the present invention will now be described by way example only and with reference to the following drawings in which: Figure 1 is a cross sectional side view of the a jaw crusher unit in which the position of the swing jaw is controlled by a wedge block assembly mounted at a back frame end region of the jaw crusher according to a specific implementation of the present invention;

Figure 2 is a perspective view of a wedge block assembly hydraulically actuated and forming part of a swing arm link assembly positionable at a back frame end of the jaw crusher of figure 1 according to a specific implementation of the present invention; Figure 3 is a plan view of the wedge block assembly having a non-integral wear part positioned at the interface between the wedge blocks according to a first specific implementation of the present invention;

Figure 4 is a plan view of the wedge block assembly in which the wear region is provided by a case hardened outer layer of the wedge blocks according to a second specific implementation of the present invention.

Detailed description of preferred embodiment of the invention Referring to figure 1 a jaw crusher unit 100 comprises a main frame 111 within which is mounted a substantially planar fixed jaw 104 having a support frame 108. A substantially planar moveable jaw 105 is mounted eccentrically at a rotatable shaft 107 and is positioned separated and opposed to fixed jaw 104. The orientation of fixed jaw 104 and moveable jaw 105 relative to one another is convergent along their respective lengths such that a separation distance between a crushing face 203 of fixed jaw 104 and a corresponding crushing face 200 of moveable jaw 105 decreases in the downward lengthwise direction. A suitable wear plate 202 is removably attached to crushing face 203 of fixed jaw 104 and a corresponding wear plate 201 is removably attached to crushing face 200 of moveable jaw 105. Main frame 111 comprises two opposed and parallel frame walls 102 either side of jaws 104 and 105. Frame walls 102 extend substantially perpendicular to a plane of jaws 104 and 105 and collectively define a crushing zone 103. The opposed fixed 104 and moveable 105 jaws are oriented to be inclined relative to one another and are spaced further apart at their respective upper ends than their lower ends. Accordingly, the crushing zone 103 is convergent from an upper feed region 204 to a lower discharge region 205.

A pair of pulley wheels 101 are mounted either end of shaft 107 at an external facing side of side walls 102 being external to the crushing zone 103. Moveable Jaw 105 is thereby configured for gyroscopic or eccentric motion with respect of fixed jaw 104 as pulley wheels 101 and shaft 107 are rotated via a suitable drive belt (not shown) attached to a drive motor (not shown). This movement of jaw 105 provides the necessary crushing action for material within zone 103 between the opposed wear plates 201 and 202.

Material to be crushed is introduced into zone 103 via the open upper region 204 where it is crushed between jaws 104, 105 and subsequently discharged via the open lower region 205. A plurality of removably mounted side liners 106 are attached to each side wall 102 at the region of crushing zone 103.

Movable (or swing) jaw 105, is supported at its lower region 110 via a mechanically actuated link assembly extending from what is typically referred to as a back frame end 117. Back frame end 117 comprises a mounting frame 113 secured to main frame 111 of crusher 100. A pair of wedge (or slide) blocks 114, 115 comprise a generally triangular wedge shaped body and are positioned in opposed sliding contact within a mounting region 118 within frame 113. An intermediate toggle plate 112 sits between wedge block assembly 114, 115 and lower frame region 110 of swing jaw 105. The toggle plate 112 is secured and mounted at its lengthwise ends via a first toggle seat 116, in contact with swing jaw region 110 and a second toggle seat 119, in contact with the wedge block 115. Accordingly, the link assembly that comprises support frame 113, wedge blocks 114, 115 and toggle plate 112 is configured to support and stabilise the oscillating movement of jaw 105 and control the separation distance between the opposed wear plates 201, 202. In particular, toggle plate 112 acts as a collapsible member that connects the rear support frame 113 to the moveable jaw 105. Referring to figure 2, each wedge block 114, 115 is mechanically attached to a respective mechanical actuator 206 formed as a hydraulic thrust-bearing cylinder. The actuator 206 comprises a cylinder 208 that acts upon a moveable piston shaft 207 mechanically attached to an end region 211 of each block 114, 115 via a pivot mounting 212. Accordingly, each actuator 206 is configured to move each block 114, 115 in the axial direction with piston shaft 207, this being in a direction substantially perpendicular to the longitudinal axis of the link assembly extending between frame 113 and lower frame region 110 of moveable jaw 105. In this configuration, jaw 105 is orientated and retained in floating manner with respect to stationary jaw 104 to allow jaw 105 to oscillate by the reciprocating motion induced by shaft 107.

Each wedge block 114, 115 comprises a hypotenuse contact surfaces 210 and 215 with each surface positioned in touching contact and configured to slide against one another via movement of each shaft 207 to and from frame 113. Accordingly, an opposed rear contact surface 209 of block 114 is positioned in sliding contact with a rear face 217 of frame 113. Similarly, a corresponding forward contact surface 218 of block 115 is configured for sliding contact against surface 214 of toggle seat 119 positioned intermediate between block 115 and toggle plate 112. As will be appreciated, the effect of pushing each block 114, 115 together is to cause toggle plate 112 to be displaced towards moveable jaw 105 to reduce the crushing gap between jaws 104, 105. Additionally, in response to a sudden loading force to jaw 105 (for example due to the presence of an uncrushable object between jaws 104, 105), toggle plate 112 is configured to break. However, if an operator wants to change the separation distance between jaws 104, 105, each cylinder 208 is actuated to displace each piston shaft 207 and in turn force each wedge block 114, 115 to slide relative to each other. Each shaft 207 is therefore capable of retreating into and extending from each respective cylinder 208. Accordingly, the wedge block assembly that principally comprises blocks 114, 115 and actuators 206, is configured to control the separation distance of jaws 104, 105 at region 205. Wedges 114, 115 are exposed to significantly high pressures resultant from crushing of material between jaws 104, 105. These high pressures often cause the wedges to seize against one another due to the high friction at opposed contact surfaces 210, 215. As indicated, seizing is problematic as the swing jaw 105 is momentarily reconfigured as a fixed jaw such that the loading forces create significant stress concentrations at other components of the crusher 100 often resulting in immediate or accumulated damage of non-wear parts. Additionally, it is common for the contact surfaces of wedges 114, 115 to rust during periods of non-use. This can fuse and lock together wedges 114, 115 or can cause momentary seizing.

Referring to figure 3, the present wedge block assembly comprises an intermediate wear part 300 in the form of a thin plate-like body mechanically attached to surface 210 of block 114. A corresponding wear part 301 is attached to surface 215 of block 115. Each plate 300, 301 is approximately sized and dimensioned to occupy the full surface area of surfaces 210, 215. Additionally, each plate 300, 301 is secured to each perspective block 114, 115 via anchorage screws that are counter-sunk through each plate 300, 301 so as to not protrude beyond the external facing surface of each respective plate, 300, 301. Each plate 300, 301 comprises a suitable wear protection material that is configured to withstand high loading forces. Advantageously the blocks 114, 115 are typically steel or grey iron (G6) iron, whilst the plate 300, 301 comprises a different material to impart different mechanical and/or physical properties to the blocks 114, 115 to optimise this region for wear and seize resistance. One requirement of the wear part 300, 301 is to ensure the appropriate level of friction is maintained between the opposed sliding wedges 114, 115. A wear material having an insufficient friction coefficient would cause the wedge blocks to be ejected from the wedge assembly in response to the significant loading forces.

Accordingly, the material of the wear part 300, 301 comprises a friction coefficient equal to or greater than that of the 'core' material of the blocks 114, 115. As will be appreciated the friction coefficient must not be too great and be sufficient to allow the blocks 114, 115 to slide relative to one another and avoid problems of seizing. According to specific implementations, the plate-like wear part 300, 301 comprises a metal and organic and/or inorganic composite; a fibre based material; an inorganic based metal composite or a ceramic material. As will be appreciated by those skilled in the art the relative higher friction materials of the wear plate 300, 301 typically comprise filler materials such as organic and inorganic (fibre and/or particulate) fillers and friction modifiers. Example friction modifiers include graphite, carbon and/or boron based materials. Additional optional materials also include zinc, brass and aluminium. The wear plate 300, 301 may also comprise binders such as resins and in particular phenolic resins.

Where the plate 300, 301 comprises a metal and organic and/or inorganic composite, the plate 300, 301 includes 20 to 80% by weight of a metal including steel wool, wire, copper and/or iron. Where the plate 300, 301 comprises an organic based metal composite, the plate 300, 301 includes 1 to 40% by weight of a metal including steel and/or copper.

Where the plate 300, 301 comprises a fibre based material, the plate 300, 301 includes glass, rubber, carbon and/or a para-aramid based material. Where the plate 300, 301 comprises a ceramic material, the plate 300, 301 includes ceramic fibres and/or metal fibres.

As will be appreciated, the wear part material 300, 301 may also be mechanically attached to the second contact surfaces 209 and 218 of each block. Accordingly, these surfaces 209, 218 are also configured to be seize resistant during sliding contact with their respective opposed mating surfaces 217, 214.

Securing wear plates 300, 301 by releasable fastenings, such as screws, allows replacement at regular intervals to ensure an optimum, undamaged, defect free plate is maintained to avoid seizing. As will be appreciated, other materials are also suitable for each wear plate 300, 301 in addition to combinations of different materials as a single plate or as a layered structure to facilitate load transmission and optimise seize avoidance. In a further embodiment, a single wear plate 300 is secured to only one block 114, with the contact surface 215 of second block 115 in direct touching contact with the single intermediate plate 300. According to further embodiments, wear part 300 may be secured in position between the opposed blocks 114, 115 by other mountings and not necessarily attached to one of the wear block 114, 115.

Referring to figure 4, a further embodiment comprises wedge blocks 114, 115 each having an integrally formed chemically distinct wear region 400 at their respective contact surfaces 210, 215 being the hypotenuse surfaces. The wear regions 400 comprise a 'case hardened' outer boundary layer of each block 114, 115. The case or surface hardening process comprises infusing chemical elements into each respective surface 210, 215 to form a thin layer or coating that is chemically distinct and harder than the inner core of each block 114, 115 (or an untreated outer region of each block). Each region 400 of the steel blocks 114, 115 is formed by defusing carbon (carburisation), nitrogen (nitriding) and/or boron (borinding) into each surface 210, 215 at high temperature and heat treating the surface layer to the desired hardness. As will be appreciated, the entire outer surface of each block 114, 115 may be case hardened and not only contact surface regions 400.

Each hardened layer 400 may comprise a thickness in a range 0.01mm to 5.0mm.

Additionally, regions 400 may comprise a multi-layer structure comprising i) an innermost diffusion layer comprising nitrogen and nitride precipitations; ii) a compound layer positioned above the diffusion layer comprising carbonitride and iii) an outer passive layer comprising iron oxide. The diffusion layer is configured to increase the hardness and fatigue strength whilst the outer passive layer increases the corrosion resistance of each block 114, 115. Accordingly, the less metallic layered region 400 significantly reduces the hardness abrasion, adhesion and seizing wear during the high pressure sliding contact between surfaces 210, 215.

In addition to the specific case hardening of surfaces 210, 215 the opposed second contact surfaces 209, 218 may also be case hardened and comprise the chemically distinct outer surface profile 400. A further specific implementation of the present invention comprises a combination of the wear part being a plate like body 300, 301 secured to any one or a combination of alternate surface 210, 215, 209, 218 and a case hardened surface region provided at any one or a combination of alternate surfaces 210, 215, 209, 218.