Patent Description:
In a cone crusher, a crusher head is supported and driven by a main shaft so as to produce crushing forces in a crushing chamber that is defined by outer and inner wear parts. The crusher head is typically either integrally formed or attached to the main shaft by cone fit or interference fit. In the latter, the crusher head or support cone defines a hole of given height and of a diameter that sufficiently expands on heating so that the crusher head can be placed onto the main shaft. On cooling to same temperature with the main shaft, the interference fit keeps the crusher head firmly in place. Interference fit is also used to attach train wheels on their shafts. Examples of crusher heads are disclosed in <CIT>, <CIT> and <CIT>.

Unlike train wheels, the interference fit of a cone crusher head is exposed to very complex dynamic force variation. The cone crusher head tends to perform a major part of the crushing work near the outmost rim that is at the bottom region of the crusher head. The main shaft has bearings that require lubrication and to isolation from the mineral material and other dirt. Therefore, there is a slip ring attached to a fixed bottom part of the cone crusher and the moving crusher head is shaped to contain an armpit like recess that receives the slip ring.

The inventors have analysed forces that are induced in the crushing process and their impact on wear appearing in the crusher head and main shaft. The armpit recess in part accents harmful forces which increase mutual sliding distance between the crusher head and the main shaft. That is, the crushing forces induce local forces at the interference fit region which sometimes exceed the forces produced by the thermal expansion (or contraction) so that mutual sliding may arise in the magnitude of tens of micro meters. This mutual sliding was studied by the inventors with respect of a number of factors including the geometry of the shaft and of the crusher head.

The inventors have now invented particular improvements in the crusher head and main shaft, which result in significant reduction of fretting wear of the crusher head and of the main shaft. It is an object of the present invention to reduce fretting wear of a cone crusher head interference fit. An alternative object of the present invention is to at least provide a new technical alternative.

According to a first example aspect there is provided a crusher head of a cone crusher, comprising:.

It is recognised that the crusher head of a cone crusher typically has a given wear part support surface angle and overhang below a bottom level of the interference fit section. By increasing the ratio of the head diameter to the armpit thickness, the interference fit section may be proportionally expanded so that deformations as a whole can be reduced in the main shaft and the crusher head. In the crusher head of the first example aspect, such deformations may be reduced so that fretting wear is reduced in the interference fit section and the work life is extended for the main shaft and / or the crusher head.

The armpit groove may be defined by an inner radius from a central axis of the crusher head and by an outer radius from the central axis of the crusher head. The central axis may be defined by the interference fit section of the crusher head or a symmetry axis of the interference fit section.

The inner radius may be continuously decreasing or same from the top of the armpit groove onwards. The outer radius may be continuously increasing or same from the top of the armpit groove onwards. The armpit groove may be free of constrictions on both sides. In result of neither inner radius increasing nor outer radius decreasing, the armpit groove may be simple to manufacture and / or refurbish.

Terms inwards and outwards may refer to directions perpendicularly towards the central axis and perpendicularly away of the central axis.

The armpit groove may have a rounded top section. The rounded top section may be defined by a first portion of a first circle of a first radius, R<NUM>, and by a second portion of a second circle of a second radius, R<NUM>. The first circle may have a first centre and second circle may have a second centre.

The first centre and second centre may be vertically aligned. The second radius may be greater than the first radius. The second centre may reside below the first centre. The second centre may be perpendicularly aligned with the interference fit section.

The first circle may extend below the interference fit section. The second circle may extend below the interference fit section. If the rounded top section is defined by a single circle, the single circle may extend below the interference fit section. By forming a relatively shallow armpit groove, deformative forces may be controlled about the armpit groove and fretting wear may be further reduced. This net effect is surprising in that the interference fit section can be formed the longer the deeper the interference fit section extends below the top of the armpit groove and so a shallower armpit portion appears to be contradicting the objective of reducing fretting wear.

The first portion of the first circle may extend on an outer side of the armpit groove at most vertically to a level of the first centre. The first portion of the first circle may extend on an outer side of the armpit groove vertically to the level of the first centre.

The first portion of the first circle may extend over a sector that extends vertically upwards from the first centre and horizontally outwards from the first centre. The first portion of the first circle may define a sector that extends vertically upwards from the first centre and horizontally outwards from the first centre. The second portion may continue inwards from the first portion. The second portion may consist of a sector of less than <NUM> degrees. The second portion may consist of a sector of less than or equal to <NUM> degrees. The second portion may consist of a sector of more than or equal to <NUM> degrees.

The inner radius may continuously decrease towards the bottom of the interference fit section. A bottom of the inner side of the armpit groove may be aligned with the interference fit section.

The inner side of the armpit groove may approach bottom of the interference fit section with a deviation angle from the central axis. The deviation angle may be at most <NUM> degrees. The deviation angle may be at most <NUM> degrees. The deviation angle may be at most <NUM> degrees. The deviation angle may be at least <NUM> degrees. The deviation angle may be at least <NUM> degrees. The deviation angle may be at least <NUM> degrees.

The outer side of the armpit groove may meet an intermediate surface with an angle greater than <NUM> degrees.

The crusher head may be configured to be laterally supported by the main shaft only by the interference fit section.

In this document, vertical and other terms based on vertical directions, such an up, down, top, and bottom, refer to longitudinal directions of the main shaft such that the top is the direction from which mineral material is received and progresses towards bottom by gravity. In operation, the main shaft may incline from one side to another, but on average, when the cone crusher is horizontally supported, the main shaft and the central axis of the crusher head can be seen as vertically aligned.

According to a second example aspect there is provided a system comprising the crusher head of the first example aspect and the main shaft.

The main shaft may comprise an interference fit section for supporting a crusher head, the interference fit section having the nominal interference fit diameter Dif.

The main shaft may comprise a bottom shaft section extending between a bottom end of the main shaft and the interference fit section. The bottom shaft section may comprise a bottom part and a neck part.

The bottom part may have a bottom part length Lbp and a bottom part diameter Dbp. The bottom part diameter Dbp may be constant below the neck part on at least <NUM> % of the bottom part length Lbp.

The neck part may have a neck part diameter that is growing towards the interference fit section.

The main shaft may have a main shaft length Lms.

For further reducing fretting wear in the interference fit section, Lms<NUM>/Dif may be at most <NUM><NUM>.

For further reducing fretting wear in the interference fit section, Dbp<NUM>/Dif may be at most <NUM><NUM>.

The main shaft length Lms may be at least <NUM>.

Advantageously, the second example aspect has been found to increase the wear lifetime of the cone crusher head of a commercial cone crusher by reducing load induced deformation of the main shaft in the interference fit section. This advantage has been realised despite an opposite effect caused by respective reduction in crusher head material thickness at the interference fit section as an increased shaft opening is needed into the crusher head.

Further advantageously, it has been found that the second example aspect enables both reducing sliding and contact dissipation energy as well as reducing stresses and stress variation induced to the cone crusher head when attached to the main shaft of the second example aspect.

Further still, it has been found that the inertia of a combination of the main shaft and the crusher head do not increase in proportion with the increased diameter, as the increased inertia on the main shaft side is compensated by reduced inertia on the crusher head side.

Still further advantageously, it has been identified that the increased diameter in the interference fit section also increases loaded surface area in the interference fit section, which further contributes to the reduction of the fretting wear, while the reduced deformation in the interference fit section is believed to mostly contribute in achieved significant work life increase.

The interference fit section may have an interference fit section length B over which the interference fit section is configured to be interference fitted with the crusher head. Dbp<NUM>/Dif may be at most <NUM><NUM>. Dbp<NUM>/Dif may be at most <NUM><NUM>. The main shaft may comprise only one interference fit section for attaching the crusher head. The interference fit section may be longitudinally continuous.

Dbp<NUM>/Dif may be at least <NUM><NUM>. Dbp<NUM>/Dif may be at least <NUM><NUM>.

The main shaft may comprise a top part from the interference fit section to a top of the main shaft.

The neck part diameter may be growing towards the interference fit section to the interference fit section diameter.

The nominal interference fit section diameter may be suited for interference fitting to a diameter of a crusher head having an interference fit of the nominal interference fit diameter.

The main shaft may be configured to laterally support the crusher head only by the interference fit section. Advantageously, by solely supporting the crusher head laterally by the interference fit section, there is no need to allow some of the height of the main shaft to be used for additional lateral supporting the crusher head. In return, the interference fit section may be made longer in the longitudinal direction and thus the fretting wear can be still further reduced. Further advantageously, machining of the crusher head is made simpler by removing a need to machine opening sections of different radiuses for the longitudinal support. Interference fit section may have a longitudinal length of at least <NUM> % of the longitudinal length or height of the cone crusher head.

According to a third example aspect there is provided a system comprising a main shaft of the second example aspect and a cone crusher head configured for interference fit attaching to the main shaft interference fit section.

The cone crusher head may be attached to the main shaft.

According to a fourth example aspect there is provided a cone crusher comprising the system of the second example aspect.

Some example embodiments will be described with reference to the accompanying Figures, in which:.

<FIG> schematically shows a main shaft <NUM> of an example embodiment. <FIG> shows some portions and dimensions of the main shaft (ms), such as a thread <NUM> for attaching a wear part (not shown) by a nut (not shown); an interference fit section <NUM>; a bottom shaft section <NUM> that comprises a bottom part <NUM> and a neck part <NUM> between the bottom part <NUM> and the interference fit section (<NUM>).

<FIG> shows some dimensions such L stands for length, D stands for diameter, and a subscript indicates the object in question.

In <FIG>, the bottom part has a constant diameter over its entire length, notwithstanding some possible rounding at the very bottom end. In some other embodiments, the bottom part may have some portions of greater or smaller diameter, but the diameter of the bottom part is present on at least <NUM> % of the length of the bottom part. It is also possible that this at least <NUM> % is formed of two or more portions.

The interference fit section has a nominal diameter Dif that is configured to fit for cone crusher heads of a shaft opening having the nominal diameter Dif. In an embodiment, one or both ends of the interference fit section have slightly greater nominal diameter, e.g., in the range of tens or hundreds of parts per million in comparison to the nominal diameter Dif.

As in <FIG>, the main shaft comprises in an example embodiment only one interference fit section for attaching the crusher head. Preferably, the interference fit section is longitudinally continuous.

As shown in <FIG>, the neck part has a neck part diameter that is growing towards the interference fit section. In <FIG> embodiment, the neck part grows to the nominal diameter, or in other words, the surface of the main shaft deviates from a perpendicular plane formed with relation to an axial direction of the main shaft, all the way from the centre of the interference fit section <NUM> over the neck part.

As also shown in <FIG> and <FIG>, the main shaft <NUM> can be configured to laterally support or at least to laterally engage with the crusher head only by the interference fit section.

In the main shaft <NUM> of <FIG>, fretting wear is reduced in the interference fit section by forming the interference section and the bottom part such that Lms<NUM>/Dif is at most <NUM><NUM>; while the interference fit section <NUM> and the bottom part are such that Dbp<NUM>/Dif is at most <NUM><NUM>.

It is appreciated that the main shaft <NUM> and a cone crusher head will form a system. The greater the diameter is at the interference fit section, the wider an opening is required in the crusher head and thus the thinner the structures will be there. It would appear intuitive to assume that since the shaft is squeezed on all sides by the interference fit attached crusher head, the system will become more prone to deformations when the diameter is increased. Surprisingly, though, it was found that in two different commercially available cone crushers, the sliding distance under different loads and fretting wear were reduced in the range of tens per cent or even more. While the entire force system is not fully understood, it is believed that the fretting wear can be reduced while Lms<NUM>/Dif is at least <NUM><NUM> or at least <NUM><NUM>.

The second condition, Dbp<NUM>/Dif, is expected to operate through dynamics over the bottom part of the main shaft that extend over the interference fit section <NUM>. In an example embodiment, this ratio is at least <NUM><NUM>. or at least <NUM><NUM>.

<FIG> shows a system <NUM> of the main shaft <NUM> and a cone crusher head <NUM> of an example embodiment. <FIG> also shows an inner wear part <NUM> attached to the cone crusher head <NUM> by a nut <NUM>. The cone crusher head <NUM> has a round arm pit groove <NUM> for receiving a slip ring <NUM> shown in <FIG>.

<FIG> illustrates some further details of the cone crusher head <NUM> of an example embodiment. In particular, <FIG> illustrates the dimensions.

In an example embodiment, the cone crusher head <NUM> comprises the conical mantle <NUM> radially extending from an interference fit section <NUM> of the crusher head. The mantle <NUM> has a wear part support surface or an outer surface and a shaft support surface configured to engage with the interference fit section <NUM> of the main shaft <NUM>.

The interference fit section has a nominal interference fit diameter Dif. It shall be appreciated that the nominal diameter of the main shaft <NUM> and of the corresponding crusher head <NUM> means slightly differing actual non-stressed diameters in room temperature. Without stress, the main shaft <NUM> would interference fit section <NUM> would not quite fit into the interference fit section <NUM> of the crusher head. Instead, when assembled with suitably heating the cone crusher head and/or cooling the main shaft <NUM>, the assembly will have the interference fit with matching effective diameters on both main shaft and the crusher head <NUM>.

The armpit groove <NUM> is covered by the conical mantle <NUM> with the armpit thickness La.

Fretting wear is reduced by dimensioning the crusher head for minimising deformations at the interference fit section so that.

In an example embodiment, as shown in <FIG>, the inner radius is continuously decreasing or same from the top of the armpit groove onwards.

In an example embodiment, as shown in <FIG>, the outer radius is continuously increasing or same from the top of the armpit groove onwards.

As mentioned, the armpit groove has a rounded top section, which can be defined by a first portion of a first circle of a first radius, R<NUM>, and by a second portion of a second circle of a second radius, R<NUM>. Advantageously, though not necessarily, the first circle and the second circle have a first centre and second circle that are vertically aligned. In an example embodiment, the second radius is greater than the first radius and / or the second centre resides below the first centre. In an example embodiment, the second centre is perpendicularly aligned with the interference fit section.

In an example embodiment, the first circle extends below the interference fit section. In an example embodiment, the second circle may extend below the interference fit section. Moreover, in an example embodiment where the rounded top section is defined by a single circle, the single circle may extend below the interference fit section.

In an example embodiment shown in <FIG> and <FIG>, the first portion of the first circle extends on an outer side of the armpit groove vertically to a level of the first centre. The first portion of the first circle may extend on an outer side of the armpit groove vertically to the level of the first centre.

In an example embodiment, the first portion of the first circle extends over a sector that extends vertically upwards from the first centre and horizontally outwards from the first centre. The In an example embodiment, the portion of the first circle defines a sector that extends vertically upwards from the first centre and horizontally outwards from the first centre. In an example embodiment, the second portion continues inwards from the first portion. In an example embodiment, the second portion consists of a sector of less than <NUM> degrees, such as less than or equal to <NUM> degrees and / or at least <NUM> degrees.

In an example embodiment, the inner radius continuously decreases towards the bottom of the interference fit section. In an example embodiment, a bottom of the inner side of the armpit groove is aligned with the interference fit section.

In an example embodiment, the inner side of the armpit groove approach bottom of the interference fit section with a deviation angle from the central axis, such as at most <NUM>; <NUM>; or <NUM> degrees; and or at least <NUM>; <NUM>; or <NUM> degrees.

In an example embodiment, the outer side of the armpit groove meets an intermediate surface with an angle greater than <NUM> degrees.

<FIG> schematically shows a cone crusher <NUM> comprising the system of <FIG>, comprising the main shaft <NUM>, the cone crusher head <NUM>, an outer wear part <NUM> and a crushing chamber <NUM> between the inner and outer wear parts <NUM>, <NUM>.

Various embodiments have been presented. It should be appreciated that in this document, words comprise; include; and contain are each used as open-ended expressions with no intended exclusivity.

Claim 1:
A crusher head (<NUM>) of a cone crusher (<NUM>), comprising:
a conical mantle (<NUM>) radially extending from an interference fit section (<NUM>), comprising a wear part support surface and a shaft support surface;
the shaft support surface comprising the interference fit section for supporting the crusher head to a main shaft;
the interference fit section (<NUM>) having a nominal interference fit diameter Dif;
the conical mantle (<NUM>) comprising an armpit groove (<NUM>) for receiving a slip ring (<NUM>);
the armpit groove (<NUM>) being covered by the conical mantle (<NUM>) with an armpit thickness La that is a minimum distance between a wear part support surface and the armpit; and
the conical mantle (<NUM>) having a head diameter Dch that is a maximum diameter of the crusher head (<NUM>); characterized in that fretting wear is reduced by dimensioning of the crusher head (<NUM>) for minimising deformations at the interference fit section (<NUM>) by:
a ratio of the head diameter Dch to the nominal interference fit diameter Dif being at most <NUM>; and
a ratio of the head diameter Dch to the armpit thickness La being at least <NUM>.