AU2008100828A6

AU2008100828A6 - Cutting pick assembly

Info

Publication number: AU2008100828A6
Application number: AU2008100828A
Authority: AU
Inventors: Jan Akerman; Craig Marshall; Michael Peatie; Steven Lee Weaver
Original assignee: Sandvik Intellectual Property AB
Current assignee: Sandvik Intellectual Property AB
Priority date: 2008-08-29
Filing date: 2008-08-29
Publication date: 2008-10-09
Anticipated expiration: 2016-08-29
Also published as: AU2008100828A4

Description

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P/00/009A Section 29

AUSTRALIA

Patents Act 1990 INNOVATION PATENT SPECIFICATION Invention Title: Applicant: CUTTING PICK ASSEMBLY Sandvik Intellectual Property AB The invention is described in the following statement: 1 7019 00 O CUTTING PICK ASSEMBLY Technical Field SThe present invention relates to a cutting pick assembly for use in machinery employed for mining and excavation.

00 00 Background Cutting picks typically are mounted in a support block of a cutter drum. The 0 cutting picks include a shank portion for mounting the pick in the support block, and a portion that projects from the support block and which usually includes a hardened cutting tip, such as a carbide tip. The pick is normally rotatably mounted in the support block so that the pick will wear more evenly. However, allowing the pick to rotate within the block causes wear of the block and the pick shank. To alleviate this wear, a wear sleeve is normally interposed between the shank and the block. The wear sleeve is usually of a hardened metal that resists wear and thus prolongs the life of the block.

Typically a wear sleeve will outlive several picks and therefore it is necessary to be able to remove the pick shank from the wear sleeve to replace the pick.

In present arrangements, this can be very difficult. A major contributor to that difficulty occurs as a result of the build-up of mining debris (dirt, dust, grit etc.) into the gap between the wear sleeve and the shank and about the rear end of the shank.

In some arrangements, the shank of the pick extends through the wear sleeve and out the rear end thereof, and the exposed end portion of the shank includes a groove for receipt of a circlip. When fitted, the circlip bears against the adjacent end of the wear sleeve and thus prevents removal of the pick through the wear sleeve.

While the above arrangement firmly secures the pick against release from the wear sleeve during operation of a cutter drum to which the cutting pick assembly is fixed, a difficulty arises when a worn pick is to be removed from W: Jie'Ancrewunriovu lUss\Cutlng Pick doc 3 o00 Sthe support block of the cutter drum. For this, access to the rear of the shank is required to remove the circlip. Often this is awkward. In addition, often the circlip has become clogged, or even covered within mining debris, which must be cleaned to allow the circlip to be accessed and removed. Often that debris is very hard and therefore difficult to remove, and thus the cleaning process 00oo can be time consuming and inconvenient.

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00 A further and significant drawback with the above arrangement, is that, 0 because removal of the circlip can be difficult, on occasions the circlip can be dropped and be lost into the mined earth which is removed for further processing. This can seriously upset the crushing process which is employed in some mining operations, as many crushers employ metal detectors to ensure that metal does not enter the crusher and damage it. A circlip will be detected by a metal detector and will shut the crusher down, with obvious downtime consequences.

In other arrangements, each of the shank and the wear sleeve include grooves which are in facing alignment when the shank is inserted into the wear sleeve, and a spring clip is received within the grooves to secure the shank within the wear sleeve. In these arrangements, the clip is inserted into the groove of the shank and radially contracts as the shank is pressed into the wear sleeve.

Upon the pick reaching the position at which the groove of the shank aligns with the groove of the wear sleeve, the clip expands into the groove of the wear sleeve, so that it is partially seated within each groove and thus exerts a retaining influence between the shank and the wear sleeve.

In order to ensure that the pick can rotate relative to the wear sleeve and the support block, the clip is allowed to expand between the shank and the wear sleeve to the point at which it is fully relaxed. Thus, it applies little or no radial load to the shank or the wear sleeve, but rather, the clip acts axially to prevent relative axial movement between the shank and the wear sleeve that would permit separation of the shank from the wear sleeve during operation of the cutter drum.

W VL~ ndrevn~nrlovmionsCCmin g Pldcdoc 00 0 An advantage of the above arrangement, is that rear access to the shank is b1 not required for removal of the shank from the wear sleeve, because the pick

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can be gripped and pulled from the wear sleeve from the front or active end of the pick using an extraction tool. This clearly differs from the earlier described arrangement which employs a circlip at the rear end of the shank, and which 00 requires access to the rear end to permit the shank to be removed from the 00 wear sleeve.

0 00 However, a drawback with the above arrangement arises as a result of the depth of the grooves into which the clip extends. The depth is significant in order to allow the clip to relax fully and because of this, the grooves are prone to become clogged with mining debris that enters between the shank and the wear sleeve. This then interferes with the process of removing a worn pick from the wear sleeve, because the mining debris can prevent radial contraction of the clip to dislodge it from the wear sleeve groove. The mining debris must therefore be cleaned out of the grooves to the extent that the clip can be radially contracted sufficient to allow the shank to be removed from the wear sleeve. This again often requires access to the rear of the shank, which, as described earlier, can be awkward, while the cleaning process itself can be time consuming and inconvenient.

It is an object of the invention to overcome or at least alleviate one or more of the drawbacks associated with the prior art.

Summary of the Invention According to the present invention there is provided a cutting pick assembly including: a pick having a body defining a shank extending from one end and a cutting tip at an opposite end, and an extraction groove positioned between the shank and the cutting tip, and a wear sleeve, defining a bore, the shank being closely received within the bore of the wear sleeve, with the extraction groove being positioned outside of the bore, and the shank W:ULie\AKrenno ato ns\C uttig Pick.doc 00 0 O having an outer surface which defines a radially outwardly opening first groove,

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the bore of the wear sleeve having a surface which defines a radially inwardly opening second groove, the first and second grooves being in facing alignment, 00oo a spring clip being disposed within the first groove and extending into oO the second groove and resisting axial disconnection between the pick and the 0 wear sleeve, oo the spring clip being biased into engagement with the first and second grooves.

A cutting pick assembly of the above kind advantageously facilitates the use of a smaller groove in the wear sleeve, compared to the grooves required in the prior art. This results from the spring clip applying or maintaining a spring load between the first and second grooves, so that the spring clip is continuously urged into the second groove under a biasing influence. This differs from the prior art, in which the groove is required to be large enough to allow the spring clip to fully relax. The spring clip is therefore is loose within the second groove and therefore does not necessarily always take up the full space within that groove.

Advantageously, a smaller groove is not only less able to accumulate mining debris, but also, in the above arrangement, the spring clip can take up more space with the groove because it is biased or urged into the groove, rather than being loosely fitted within the groove. There is therefore overall, less room available in the groove for mining debris to accumulate.

According to the present invention there is also provided a cutting pick having rotational axis and including: a body and a stepped shank extending from one end of the body and a cutting tip at an opposite end, and an extraction groove positioned between the shank and the cutting tip, the axial length of the shank being less than the axial length of the body, W:Ule\rewUnvtia os\Cu uth Pick.doc 00 the shank having a step between a large diameter section which e extends from the body and a small diameter section, the axial distance from d) said step to the free end of the shank defining an axial distance Y, a spring clip being disposed in a first groove adjacent to the free end of the shank and extending a distance X laterally to the rotational axis, said distance X being 00 greater than said axial distance Y,

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00said body further having a shoulder extending perpendicularly to the _rotational axis.

00oo A further advantage of the present invention is that the pick can be disconnected from the wear sleeve from the front or active side of the pick and access to the rear of the pick will rarely be required. It is the use of the spring clip rather than of the circlip as in the prior art, which enables this advantage to be provided. Moreover, because there is less likelihood of mining debris clogging the grooves in which the spring clip is accommodated, the need for rear shank access to remove mining debris from the grooves is also less likely.

As a result, replacement picks can be installed more conveniently and quickly.

A standard extraction tool can be employed for pick removal.

In one form, the axial length of the shank is less than the axial length of the wear sleeve, so that a recess is formed between the end of the shank and the internal surface of the bore. In this arrangement, a sealing medium can be provided in the recess to seal between the end of the shank and the internal surface of the bore.

In the above arrangement, the ingress of mining debris between the wear sleeve and the shank, and into the first and second grooves, is resisted by the sealing medium. Accordingly, there is reduced likelihood of the first and second grooves becoming clogged with debris, so that it is less likely that the spring clip could be prevented from radial contraction for separation of the pick from the wear sleeve. This further contributes to replacing and installing picks more conveniently and quickly.

W.ULje*eAndrMSpe837195 Amenled PageSdoC 00 O Still further, in the cutting pick assemblies described above, a circlip is not required. This means that the potential for loss of a circlip into the mined earth is eliminated and therefore, the possibility of a circlip being detected by a metal detector and shutting down a crusher is eliminated.

00 Brief Description of the Drawings oO For a better understanding of the invention and to show how it may be 0 performed, embodiments thereof will now be described, by way of non-limiting 0 example only, with reference to the accompanying drawings.

Figures 1 and 2 show side and cross-sectional views respectively of a cutting pick assembly according to the invention.

Figure 3 shows a side view of the pick of Figures 1 and 2.

Figure 4 shows a perspective view of an extraction tool for use with the cutting pick assembly of Figures 1 and 2.

Detailed Description of the Drawings Figures 1 and 2 show side and cross-sectional views respectively of a cutting pick assembly according to the invention.

The cutting pick assembly 10 includes a pick 11, a carbide cutting tip 12 which is brazed or otherwise fixed within a recess 13 in the pick 11, a wear sleeve 14 and a spring clip The pick 11 includes a bell-shaped body 16, which extends to an extraction groove 17. The extraction groove 17 is provided for engagement with an extraction tool which will be described later herein.

The pick 11 defines a shoulder 18 and a stepped shank 19. The shank 19 forms an axial recess for receipt of the wear sleeve 14, with the outer diameter of the shoulder 18 being approximately equal to the diameter of the wear W:UubeWreW nnovaiotsCW Ag Picd.doc 00 0 (sleeve 14 adjacent the shoulder 18. It can be seen from the figures, that the wear sleeve is tapered to a smaller diameter remote from the shoulder 18.

The shank forms a step 20 and a radially outwardly opening groove 21, within which the spring clip 15 is disposed. The wear sleeve 14 also forms a step at 00oo 22, complementary to the step 20 and also forms a groove 23 which opens oo radially inwardly and which is in facing alignment with the groove 21. The 0 groove 23 is curved and of a shallow depth particularly when compared to the 00 depth of the groove 21.

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The depth of the groove 23 is also shallow when compared to the depth of grooves which have been provided in the wear sleeves of prior art cutting pick assemblies. Thus, the overall volume created by the two grooves 21 and 23 is less than the like grooves which are provided in prior art arrangements. The present inventors have discovered that a shallow groove 23 provides benefits as to reducing or eliminating clogging of the grooves 21 and 23 by mining debris. The inventors have discovered additionally, that by maintaining the spring clip 15 in compression within the grooves 21 and 23, the reduced size of the groove 23 does not adversely affect the resistance to disconnection of the pick from the wear sleeve, which is at least sufficient under operating conditions of the cutting pick assembly to maintain the shank 19 secured within the wear sleeve 14.

Still further, by maintaining the spring clip 15 in compression, it is forced into the grooves 21 and 23 to take up a greater volume of space within those grooves than would otherwise be the case if the clip 15 was a loose fit within the grooves. This again reduces the potential for clogging of the grooves 21 and 23, by minimising the available area within the grooves into which mining debris can enter.

Referring to Figure 3, this is a side view of the pick 11 of Figures 1 and 2 and shows the spring clip 15 attached to the shank 19 within the groove 21. It can be seen that the spring clip 15 includes a radial projection 24 which is shaped W:U u endre llonovaiorns'CUtl PiC.doc 00 0 O for snug receipt within the groove 23 of the wear sleeve 14. It can also be seen that the wear sleeve 14 is formed from a broken ring, which allows radial

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contraction and expansion.

The method of assembling the cutting pick assembly 10 is to attach the spring o00 clip 15 to the groove 21 of the pick 11 and to thereafter insert the shank 19 into

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oO the bore 25 of the wear sleeve 14. When the shank reaches the reduced diameter neck 26 of the wear sleeve 14, the spring clip 15 will be forced to 0 radially contract until the projection 24 of the spring clip 25 is aligned with the groove 23 of the wear sleeve 14. Upon that alignment, the spring clip 15 will radially expand into the groove 23, although the expansion is arranged to be insufficient for the spring clip 15 to completely relax. Thus, the spring clip remains in compression.

A further advantage provided by a pick assembly according to the present invention, is that the clearance between the wear sleeve 14 and the shank 19, above the steps 20 and 22, is greater than in prior art arrangements and therefore there is improved rotation of the pick 11 relative to the wear sleeve of 14 during operation of a cutter drum. The greater clearance is beneficial, to allow for expansion of the shank 19 upon heat build-up.

Figure 4 illustrates an extraction tool 30, which includes a pick engagement head 31, a shaft 32, a slidable weight 33 and a handle 34. The shaft 32 extends between the engagement head 31 and the handle 34 and the weight 33 is slidable fully along the shaft 32.

To extract the pick 11 from the wear sleeve 14 mounted within a support block, the head 31 is fitted about the pick 11, so that an inwardly extending lip 36 nests within the extraction groove 17 of the pick 11. Thereafter, the weight 33 is slid rapidly along the shaft 32, from adjacent the head 31, and into impact engagement with the flange 35. The resulting impact load is transferred through the head 31 to the pick 11 in order to dislodge the pick 11 from the W:A.J uLend r6vaP o %Cu lng PIck €oc oo wear sleeve 14. The pick can therefore be removed quickly and easily and by eC employing an extraction tool which already exists.

In a cutting pick of the present invention, the axial distance Y from the shoulder 20 to the free end 27 of the shank 19, is less than the maximum distance or Sdiameter X of the spring clip 15. This facilitates a compact shank arrangement 0 and permits the shank to terminate in advance of the wear sleeve, to create a recess for receipt of a sealing medium.

o0O c- 10 The invention described herein is susceptible to variations, modifications and/or additions other than those specifically described and it is to be understood that the invention includes all such variations, modifications and/or additions which fall within the spirit and scope of the above description.

WJule Arndre WSpe l837195 Amended Page .doc

Claims

1. A cutting pick assembly including: Sa pick having a body defining a shank extending from one end and a cutting tip at an opposite end, and an extraction groove positioned between the 00oo shank and the cutting tip, and 0 oO a wear sleeve, defining a bore, the shank being closely received within the bore of the wear sleeve, with 0 the extraction groove being positioned outside of the bore, and the shank having an outer surface which defines a radially outwardly opening first groove, the bore of the wear sleeve having a surface which defines a radially inwardly opening second groove, the first and second grooves being in facing alignment, a spring clip being disposed within the first groove and extending into the second groove and resisting axial disconnection between the pick and the wear sleeve, the spring clip being biased into engagement with the first and second grooves.

2. A cutting pick assembly according to claim 1, the axial length of the shank being less than the axial length of the wear sleeve, so that a recess is formed between the end of the shank and the internal surface of the bore, a sealing medium being provided in the recess to seal between the end of the shank and the internal surface of the bore.

3 A cutting pick assembly according to claim 1 or 2, the second groove having a depth radially of between 0.25mm and 1.00mm

4 A cutting pick having rotational axis and including: a body and a stepped shank extending from one end of the body and a cutting tip at an opposite end, and an extraction groove positioned between the W uliOAnMrv n~lomobng Pick doc 00 Sshank and the cutting tip, the axial length of the shank being less than the axial C length of the body, the shank having a step between a large diameter section which extends from the body and a small diameter section, the axial distance from said step to the free end of the shank defining an axial distance Y, a spring clip 0 being disposed in a first groove adjacent to the free end of the shank and Sextending a distance X laterally to the rotational axis, said distance X being greater than said axial distance Y, 0said body further having a shoulder extending perpendicularly to the c 10 rotational axis. A cutting pick assembly or cutting pick substantially as herein described with reference to the accompanying drawings. W:UuUelAndrewtSpeci\37195 Amended Pages doc