GB2249116A

GB2249116A - Mineral cutter pick and tip

Info

Publication number: GB2249116A
Application number: GB9122268A
Authority: GB
Inventors: John William Haddock
Original assignee: Hydra Tools International PLC
Current assignee: Hydra Tools International PLC
Priority date: 1990-10-23
Filing date: 1991-10-21
Publication date: 1992-04-29
Anticipated expiration: 2011-10-21
Also published as: GB2249116B; DE4134739A1; GB9023029D0; GB9122268D0

Abstract

A mineral cutter pick (1) of the radial attack type or forward attack type comprising an integral head (2) and shank (3) of steel, and a carbide tip (4) brazed into a seat (6) machined into the head (2), both the seat (6) and seating surface(s) of the tip (4) being such that, in addition to the braze, there is mechanical inter-engagement (17) between the head (2) and the tip (4) to provide mechanical resistance by the head (2) against lateral forces on the tip (4). Many different forms of mechanical inter-engagement are described. <IMAGE>

Description

224 911 c) MINERAL CUTTER PICK AND TIP The invention relates to a mineral

cutter pick and tip, of the radial type or of the f orward attack type, adapted to be mounted on a rotary cutting'head or chain of a mineral cutting machine.

Conventionally, such picks comprise an integrally forged steel head and shank, with the head machined, e.g. by milling, to provide a step or notch to receive a hard material cutting tip, e.g. of tungsten carbide, brazed in position.

Despite the brazing, tip loss occurs for various reasons and is not usually realised until a detailed inspection of all the picks (eg 50 of st rotary cutting head), are examined. Apart from loss of cutting efficiency and premature wear of the pick head occurs, perhaps to the extent that the pick can only be scrapped. Furthermore, if the mining of coal, and hence methane release, is involved, tip loss additionally presents a hazard in that spontaneous ignition frequently occurs in the so-called incendive sparking zone behind the head due to the elevated working temperature of the pick adjacent this zone, leading to the need to adopt various ventilating-and/or water quenching precautions, with attendant costs.

Whilst tip loss can occur in time by virtue of wear, diminution of the braze etc, premature loss also occurs because of the standard practice of locating the picks at an angle with respect to the cutting direction, particularly at the face side end of a rotary cutting head, resulting in lateral forces being applied to the tip which the brazing was 2 never intended to resist. Furthermore, reverse rotation of a head, or reverse driving of a chain, either accidentally or deliberately if the head or chain has become stuck in the mineral, frequently results in the braze being insufficiently strong to resist the tips being pulled from the picks.

Furthermore, in the cutting of certain minerals such as potash, the pick is subjected to high temperatures with the result that low temperature braze materials (suitable for coal cutting for example) are unsatisfactory and a high level of tip losses results. High temperature braze materials are of course known and whilst these would to a large extent alleviate the tip loss problem, other metallurgical problems are introduced in that, unless specialised heat treatments are employed, requiring capital equipment and hence increasing pick manufacturing costs, cracks in the pick head will result, with such frequency that an unacceptably high proportion of scrap picks will be produced.

According to a first aspect of the present invention, there is provided a mineral cutter pick of the radial attack type or forward attack type comprising an integral head and shank of steel, and a carbide tip brazed into a seat machined into the head, both the seat and seating surface(s) of the tip being such that, in addition to the braze, there is mechanical :nter-engagement between the headland the tip to provide mechanical resistance 'by the head against lateral forces on the tip.

Thus, with the:pick in accordance with the invention, a portion of the steel of the head is employed to resist at braze the least lateral forces tending to detach of the tip.

The invention can be realised in several ways.

Thus, in accordance with a first embodiment, there is provided a mineral cutter pick comprising a blind hole drilled into the head to receive a hard material tip, and with the hole opened longitudinally along a front face of the pick.

According to another aspect of the invention of independent significance, there is provided a tip approximating in length to the depth of the hole into which it is to be fitted and having a part circular cross-section matching that of the hole into which it is to be fitted and a linear nose portion.

Thus, the tip is retained in position not only by braze material but also mechanically, with the result that should such operational temperature be encountered that the material fails, automatic tip loss does not result as mechanical interengagement ensures retention.

Furthermore, the ability to use low temperature braze materials avoids metallurgical damage to the pick head and hence costly heat treatments or the production of an unacceptably high proportion of scrap picks.

In detail, the opening of the blind hole in the head may be effected by milling or grinding to provide in effect an OPen slot along the front of the hole.

The cross-section of the tip is a true circle over a 0 major proportion (i.e. in excess of 180) of diameter slightly less than the hole diameter running into two converging, tangential surfaces to provide an apex, resulting in a sharp - 4 cutting edge along the length of the tip and, projecting from the slot of the hole.

In accordance with another embodiment, there is provided a mineral cutter pick-wherein the tip has a seating surface provided with cruciform, ribs and the pick with complementary rib-receiving slots.

According to another aspect of the invention of independent significance, there is provided a tip for a mineral cutter pick, the tip having a seating surface provided with cruciform ribs and the pick with complementary ribreceiving slots.

In accordance with another embodiment there is provided a mineral cutter pick, wherein the seat is provided with a blind hole and the tip is provided with a complimentary 15 projecting peg, so that peg-to-hole engagement provides the mechanical inter-engagement.

According to another aspect of the invention of independent significance, there is provided a tip for a mineral cutter pick, the tip having a projecting peg, and the 20 seat having a blind hole for engagement by the projecting peg.

In accordance 'with another embodiment, there is provided a mineral cutter pick, wherein the se at is provided with" a projecting peg and the tip with a complementary blind h,ole, so that peg- to-hole engagement\provides the mechanical inter-engagement.

According to another aspect of the invention of independent significance, there is provided a tip for a mineral cutter pick, the tip having a blind hole for location in situ, on a projecting peg of a seat so that peg-to-hole engagement provides for mechanical inter-connection between the tip and the seat.

In accordance with another embodiment, there is provided a mineral cutter pick wherein the tip has a shallow, V-shaped indentation on seating surfaces thereof to engage a complementary V-shaped projection of the seat, to provide the mechanical inter-engagement.

According to another aspect of the invention of independent significance, there is provided a tip for a mineral cutter pick, the tip having a shallow, V-shaped indentation to provide seating surface to engage, in use, a seat in the form of a complementary V-shaped projection of the head, to provide for mechanical inter-engagement between the tip and seat. I In accordance with another embodiment, there is Provided a mineral cutter pick comprising an integral head and shank, the head is provided with side cheeks defining lateral sides of the seat, and hence defining a tip-receiving slot, the side cheeks providing the mechanical inter-engagement.

According to another aspect of the invention of independent significance, there is provided a tip for a mineral cutter pick, the tip havingputually facing, spacedapart side cheeks defining seating surfaces and hence defining a receiving slit for a seat in the form of a rib, the side cheeks providing mechanical inter-engagement with the ribbed seat.

In accordance with another embodiment, there is provided a mineral cutter pick wherein the seat is provided with a frusto conical recess to receive a frusto-conical projection of the tip, to provide mechanical inter-engagement.

According to another aspect of the invention of independent significance, there is provided a tip for a mineral cutter pick having a frusto-conical projection comprising the seating surface of the tip.

Preferably, the pick head and shank are integrally forged in steel (e.g. EN19), while the tip is oftungsten carbide.

Examples of picks in accordance with the invention are shown in the accompanying drawings, in which:

Figure 1 is a side elevation of a first embodiment of pick; Figure 2 is a plan view of Figure 1; Figures 3, 4 and 5 are respectively front elevation, side elevation and plan views of the tip portion of the pick of Figures 1 and 2; Figure 6 is a side elevation of a second embodiment of pick; Figures 7 and 8 are respectively front 'and plan views of the tip portion of Figure 6; Figure 9 is a side elevation of a third embodiment of pick; Figures 10 and 11 are respectively front and plan views of the tip portion of Figure 9; Figure 12 is aside elevation of a fourth embodiment of pick; X Figures 13 and 14 are respectively front and plan view of the tip portion of Figure 12; Figure 15 is a side elevation of a fifth embodiment of pick; Figures 16 and 17 are respectively front andplan views of the tip portion of Figure 15; Figure 18 is a side elevation of a sixth embodiment of pick; Figures 19 and 20 are respectively front and plan views of the tip portion of Figure 18; Figure 21 is a side elevation of a seventh embodiment of pick; Figures 22 and 23 respectively are front and plan views of the tip portion of Figure 21; Figure 24 is a side elevation of an eighth embodiment of pick; Figures 25 and 26 are respectively front and plan views of the top portion of Figure 24; Figure 27 is a side elevation of a ninth embodiment of pick; and Figures 28 and 29 respectively are front and plan views, of the pick of Figure 27.

In all embodiments, like components are accorded like reference numerals.

A mineral cutter pick 1 of the radial or forward attack type comprises an integral head 2 and shank 3 of steel. A carbide tip 4 having seating surfaces 5 is brazed into a complementary seat 6 machined into the head 2. Whilst the 8 - braze material normally holds the tip in place, in accordance with a basic feature of the invention, the tip 4 is additionally held in position by mechanical inter-engagement between the tip 4 and the head 2.

In the embodiments of Figure 1,- mechanical interengagement is achieved by drilling a blind hole 7, with the hole 7 then opened longitudinally by milling or grinding into a slot 8. The tip 4 of Figures 3 to 5 has a partcircular cross section 9 matching that of the hole 7, approximately in length to the depth of the hole 7, and has a linear nose portion 10 corresponding in length to the slot 11. In detail, the tip 4 has a circular cross-section in excess of 0 of slightly less diameter than the diameter of the hole for ease of fitting and to accommodate braze material. The circular cross-section runs into two converging tangential surfaces 12 to an apex defined by the nose portion 10. Thus, when the tip 4 is fitted into the hole 7 the nose portion 10 projects through the slot 8 to define a sharp cutting edge along the length of the tip, while an upper tip surface 13 is contiguous with upper surface 14 of the head 2, while the nose portion 10 projects slightly beyond a front surface 16 of the head 2, with arms 17 of the head 2 embracing the tip to provide, in addition to the usual low termerature brazing material, mechanical engagement between the tip 4 and head 2 and hence tip retention even if the braze fails.

In the embodiment of Figures 6 to 8 and 9 to 11 is shown a pick 1 provided with cruciform slots 18 constituting the seat 6 to receive the tip 4, the latter being provided with cruciform ribs 15 so that, when the tips 4 are fitted to the heads 2, as illustrated in Figures 6 and 9, arms 17 of the heads 2 retain the tips 4 in position, in addition to the usual braze material.

In the embodiment of Figures 12 to 14 the seat 6 of the head 2 incorporates a blind hole 19, whilst the tip 4 is Provided with a projecting peg 20 of cross-section and length to fit the hole 19, so that firstly mechanical retention is afforded by the hole 19. Additionally, the seat 6 is provided with four arms 17 again to provide for mechanical retention of the tip 4.

In the embodiment of Figures 15 to 17 the situation is reversed in comparison with the embodiment of figures 12 to 14, in that the seat 6 of the head 2 is provided with a projecting peg 21, while a blind hole 22 is formed in the seating surface 5 of the tip 4, whereby mechanical retention of the tip 4 on the head 2 is provided by the peg 21, in addition to the usual braze material.

In the embodiment of Figures 18 to 20 the seat 6 is Provided with a generally cruciform slot, with lateral faces of the head 2 having a rectangular slot 23 while, as illustrated in Figure 19, the front face of the head 2 is provided with an obtuse angled slot 24, and the tip 4 is provided with complimentary seating surfaces 5, with 26 and converging lateral faces 25 leading to a front apex with curved lateral faces 27 at the rear of the tip.

In the embodiment of Figures 21 to 23 the seat 6 comprises a planar portion 28 and a "V"-projection 29, while - 10 the tip 4 has a complimentary "V"-shaped indentation 36 on seating surfaces 5, to provide the mechanical interengagement.

In the embodiment of Figures 24 to 26, the head 2 is provided with side cheeks 30 defining lateral sides of the seat 6, and hence defining a tipreceiving slot 31, to receive a "D"-shaped tip 4 secured firstly by brazing and secured mechanically by the cheeks 30.

In the embodiment of Figures 27 to 29 the seat 6 is provided with a frusto-conical recess 32 to receive a frusto conical projection 33 of the seating surface 5 of the tip 4, the steel of the head surrounding the projection 33 providing the mechanical retention, in addition to the brazing.

Furthermore, the upper surface of the head of the pick is preferrably ground away at 34, so that a relatively long, upper surface 35 of the tip is exposed, to minimise steel-torock contact in the so- called incendive sparking zone behind the tip 4, to minimise spontaneous combustion, if the mining of coal is involved.

1 1 k

Claims

1. A mineral cutter pick of the radial attack type or forward attack type comprising an integral head and shankof steel, and a carbide tip brazed into a seat machined into the head, both the seat and seating surface(s) of the tip being such that, in addition to the braze, there is mechanical inter-engagement between the head and the tip to provide mechanical resistance by the head against lateral forces on the tip.

2. A pick as claimed in Claim 1, wherein the seat comprises a blind hole drilled into the head to receive a hard material tip, and with the hole opened longitudinally along a front face of the pick.

3. A pick as claimed in Claim 2, wherein the opening of the hole is effected by milling or grinding to provide in effect an open slot along the front of the hole.

4. A tip for the pick of any one of Claims 1 to 3, the tip approximating in length to the depth of the hole of the pick and having a part circular cross-section matching that of the hole, and a linear nose portion.

5. A tip as claimed in Claim 4, wherein the cross-section of the tip is a true circle over a major proportion (i.e. in - 0 excess of 180 of diameter slightly less than the hole diameter running into two converging, tangential surfaces to provide an apex, resulting in a sharp cutting edge along the length of the tip and,. in situ, projecting from the slot of the hole.

A pick as claimed in Claim 1, wherein the tip has a seating surface provided with cruciform ribs and the pick with complementary rib-receiving slots.

7. A tip for a mineral cutter pick as defined in Claim 6, the tip having a seating surface provided with cruciform ribs and the pick with complementary rib-receiving slots.

8. A pick as claimed in claim 1, comprising a tip with seating shoulders and an integral peg, the peg penetrating a blind bore in the pick head to provide the mechanical inter engagement.

9. A tip for a mineral cutter pick.

seating shoulders and an integral peg to define seating surfaces, the peg being adapted to penetrate a blind bore in a pick head to provide, in use, mechanical inter-engagement between the tip and head.

10. A pick as claimed in Claim 1, wherein the seat is provided with a blind hole and the tip is provided with a complimentary peg, so that peg-to-hole engagement provides the mechanical engagement.

A tip for a mineral cutter pick as claimed in Claim in Claim 10, the tip having a projecting peg for location in a blind hole of a seat of-the pick.

12. A pick as claimed in Claim 1, wherein the seat is provided with a projecting peg and the tip with a complementary blind hole, so that, pegto-hole engagement provides the mechanical interengagement.

13. A tip for a mineral cutter pick as defined in Claim 12, the tip having a blind hole for location on a projecting peg of a seat of the pidk head.

the tip having

14. A pick as claimed in Claim 1, wherein the tip has a shallow, V-shaped indentation on seating surfaces thereof to engage a complementary V- shaped projection of the seat, to Provide the mechanical inter-engagement.

15. A tip for a mineral cutter pick as defined in Claim 14, the tip having a shallow, V-shaped indentation to provide seating surface to engage, in use, a seat in the form of a complementary V-shaped projection of the head, to provide for mechanical inter-engagement between the tip and seat.

16. A pick as claimed in Claim 1, wherein the head is provided with side cheeks defining lateral sides of the seat and hence defining a tipreceiving slot, the side cheeks providing the mechanical inter-engagement.

17. A tip for a mineral cutter pick as defined in Claim 16, the tip having mutually facing, spaced-apart side cheeks defining seating surfaces, and hence defining a receiving slit for a seat in the form of a rib, the side cheeks providing mechanical inter-engagement with the ribbed seat.

18. A pick as claimed in any one of Claims 1 to 3, 6, 8, 10, 12, 14 and 16, wherein the pick head and shank are integrally forged in steel.

19., A tip as Claimed in any one of Claims 4, 5, 7, 9, 11, and 13, wherein the tip is of tungsten carbide.

20. A pick substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.

21. A pick substantially as hereinbefore described with reference to Figures 6 to 8 of the accompanying drawings.

22. A pick substantially as hereinbefore.described with reference to Figures 9 to 11 of the accompanying drawings.

23. A pick substantially as hereinbefore described with reference to Figures 12 to 14 of the accompanying drawings.

24. A pick substantially as hereinbefore described with reference to Figures 15 to 17 of the accompanying drawings.

25. A pick substantially as hereinbefore described with reference to Figures 18 to 20 of the accompanying drawings.

26. A pick substantially as hereinbefore described with reference to Figures 21 to 23 of the accompanying drawings.

27. A pick substantially as hereinbefore described with reference to Figures 24 to 26 of the accompanying drawings.

28. A pick substantially as hereinbefore described with reference to Figures 27 to 29 of the accompanying drawings.

29. A tip, substantially as hereinbefore described with reference to Figures 3 to 5 of the accompanying drawings.

30. A tip, substantially as hereinbefore described with reference to Figures 6 to 8 of the accompanying drawings.

31. A tip, substantially as hereinbefore described with reference to Figures 9 to 11 of the accompanying drawings.

32. A tip, substantially as hereinbefore described with reference to Figures 12 to 14 of the accompanying drawings.

33. A tip, substantially as hereinbefore described with reference to Figures 15 to 17 of the accompanying drawings.

34. A tip, substantially as hereinbefore described with reference to Figures 18-to 20 of the accompanying drawings.

35. A tip, substantially as hereinbefore described with reference to Figures 21 to 23 of the accompanying drawings.

36. A tip, substantially as hereinbefore described with 1 L, - reference to Figures 24 to 26 of the accompanying drawings.

37. A tip, substantially as hereinbefore described with reference to Figures 27 to 29 of the accompanying drawings.