EA016278B1 - Cutting tip and tool - Google Patents

Abstract

A cutting tip (10) for a mechanical excavator comprises a tip body (11) having a generally pointed distal end (12), a proximal end (13) spaced from the distal end, and a wall (14) that diverges outwardly from the distal end towards the proximal end. The wall (14) is profiled to induce a non-uniform stress profile on the material impacted by the cutting tip to facilitate radial cracking in that material. In one form, the wall (14) is profiled to include a plurality of ridges (15) and intermediate regions (16), with the ridges (15) being arranged to induce a higher stress concentration in the impacted material than the intermediate regions (16).

Description

FIELD OF THE INVENTION

The invention generally relates to methods for mechanically excavating soils and the equipment required for this, and more specifically to cutting tools (commonly called cutters) for use in such processes. The present invention has been developed specifically for mechanical excavators used in the mining industry, and the invention is described here in this context. However, it should be understood that the present invention has wider application and is not limited only to this particular application.

State of the art

Mechanical excavators equipped with cutters are widely used in the extraction of rock and coal in the mining industry. Such equipment includes roadheaders, continuous miners and long-face miners. One of the most widely used incisors is a point impact incisor (also known as a conical incisor). The tip of these cutters, which is directly involved in the cutting process, has a conical shape and is made of high hardness material, such as tungsten carbide. These cutters are especially popular because they have a relatively long life.

Despite the popularity of point impact incisors, they are known to cause a large amount of dust due to the indenter impact, which the conical cutter produces at the point of impact when it crushes a large amount of coal / rock. Excessive dust is the biggest problem, especially in underground coal mining, as it affects health, leading to ailments such as black lungs (pneumoconiosis), the deadliest disease of miners. Conventional measures to control excessive dust generation, such as blowing large volumes of air at high speed, spraying water and installing air-cleaning scrubbers are expensive and not effective enough. In addition, in addition to the fact that the impact cutter leads to severe dust, it is known to be excessively energy-intensive and produces too much noise (which can lead to miners hearing loss), and it also leads to the formation of excess amounts of coal fines, which is more difficult to process at the plant, and therefore the processing of such coal becomes more expensive.

Disclosure of invention

According to one aspect of the present invention, there is provided a cutting tip of a mechanical excavator comprising a body having a substantially pointed distal end, a proximal end located at a distance from the distal end, and a wall that diverges outward from the distal end to the proximal end, the wall having such a profile so as to have an uneven load distribution on the material subjected to the impact of the cutting tip to facilitate the formation of radial cracks in this material.

In view of the foregoing, an improved cutting tip is proposed which is applicable to point impact cutters (having a pointed distal end). The cutting tip described in the present invention has a special profile shape to provide an uneven load distribution in order to promote the formation of radial cracks on the material to be impacted. Thus, this cutting tip is different from a conventional conical tip, which provides an even distribution of the load on the impacted material.

A common conical tip has a compressive effect on the material at the point of contact with it, when the indenter action of the cutter causes a large number of round cracks, and this cracking leads, in turn, to the formation of a large number of small particles in such a brittle material as coal and rock . In contrast, according to the aforementioned aspect of the present invention, the cutting tip is designed to cause cracking of a different nature in the material, with a high likelihood of radial cracks, which in turn contributes to the extraction of large pieces of rock and also the formation of less dust by reducing the number of round cracks. Since in this process a smaller amount of rock is crushed, the energy consumption in this case is also reduced, and less noise is produced, and the cutter / tip wears out less.

In one embodiment, the cutting tip has an axis, and the distal and proximal ends are spaced apart from each other along this axis. In addition, the tip body wall has such a profile as to include a plurality of axially extending ribs and intermediate regions located between the ribs. The ribs are arranged so as to cause a more concentrated load in the impacted material than the load caused by the intermediate regions, thereby providing an uneven load profile.

Profiling the walls of the body of the tip to obtain these ribs can take various forms. Namely, the ribs may extend to the proximal end of the tip body, or they may not extend to the proximal end. In a preferred embodiment, these ribs extend to the far end, however, in another embodiment, at least some of these ribs

- 1 016278 may not reach the far end. Each rib can be continuous or intermittent, while some or all of them can be made of many aligned shorter segments that together form an axially extending rib. In addition, individual ribs can extend only in the direction of the axis of the tip, or, alternatively, they can extend both axially and radially with respect to this axis, so that these ribs form a spiral on the wall of the body of the tip.

In one embodiment, at least some of the adjacent intermediate regions are mutually inclined. In this design, the ribs are located between the respective mutually inclined intermediate sections and form the edges on the body of the tip. In another embodiment, adjacent intermediate regions can be aligned so that the rib will be an element delimiting the planes of these aligned adjacent intermediate regions.

In one embodiment, the intermediate regions may act as the cutting surface of the tip. In this design, at least one of the intermediate regions may be substantially flat in at least one portion of this region. However, the intermediate regions may not only be flat, but also have an arched profile in at least one portion of their length. In this design, each rib has a radius of curvature significantly smaller than the corresponding radius of curvature of the arcuate intermediate region.

The intermediate region, which includes an arcuate section, may be convex, concave, or have a more complex shape, including any combination of a flat, concave, or convex section.

In one embodiment, the tip body includes at least three ribs.

In a specific embodiment, the body of the cutting tip has a proximal end that is polygonal. In addition, in another specific embodiment, the ribs extend from the angles of the proximal end so that the number of ribs corresponds to the number of sides of the polygon.

The size of the cutting tip may vary depending on the tool in which the tip is used. In one embodiment, the ribs have a radius of curvature from 0.1 to 20 mm. In addition, the wall of the body of the tip or ribs diverges outward to the proximal end with a taper angle of 30 to 170 °. In one embodiment, the angle is such that during operation upon impact, the cutting tip forms a negative rake angle. Moreover, the value of the taper angle of the tip body, leading to a negative index of the rake angle, depends on the angle of inclination at which the cutting tool is in contact with the surface of the material being processed. However, typically a taper angle ranging from 100 to 140 ° may be sufficient to achieve a negative rake angle. The advantage of the negative rake angle is that it can increase the compressive stress acting on the material being treated, thereby contributing to its cracking.

In one embodiment, the distal end has a tip radius of 0.2 to 5 mm.

Typically, the cutting tip is configured to be mounted on the head of the cutting tool. In one embodiment, a connecting member is provided at the proximal end of the tip body to facilitate this installation. In one embodiment, the connecting element is a protrusion configured to fit in a corresponding recess in the head of the cutting tool. In an alternative embodiment, the connecting element is in the form of a recess, and the head of the cutting tool has a corresponding protrusion. Typically, the cutting tip is firmly mounted on the tool head by any suitable means, such as welding, or using mechanical fasteners.

Such tips are made of high hardness material such as sintered tungsten carbide. However, other materials of high hardness, such as diamond, polycrystalline diamond (RSE), can also be used to make the tip. cubic boron nitride (CBFB) and polycrystalline cubic boron nitride (CBFB), which will be apparent to those skilled in the art.

In another embodiment, the present invention relates to a cutting tool comprising a head housing and a cutting tip made in accordance with any embodiment described above and located on the front end of this head housing. In a particular embodiment, the cutting tool is adapted to be mounted in the tool holder so that it can be rotated about a central axis that passes through the cutting tip.

One of the advantages of a cutting head made according to the aforementioned embodiment is that it can be mounted on conventional excavators that were previously intended for use with point impact tools having conical tips.

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Brief Description of the Drawings

It seems logical to further describe embodiments of the present invention with reference to the accompanying drawings. It should be noted that the features of the present drawings and the corresponding description should be understood as not replacing the General provisions of the previous detailed description of the present invention.

In the drawings of FIG. 1 is a schematic view of a cutting tool according to one embodiment of the present invention;

FIG. 2 is a side view of the cutting tip of the tool shown in FIG. one;

FIG. 3 is a top view of the tip shown in FIG. 2;

FIG. 4 is a bottom view of the tip shown in FIG. 2;

FIG. 5 is a schematic view of yet another embodiment of a cutting tool according to the present invention;

FIG. 6 is a schematic view of the position of the cutting tool shown in FIG. 1 by impact on the surface of the material; and FIG. 7 is a schematic representation of the cracking behavior of a brittle material as a result of impact on it with the cutting tip shown in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1 shows a cutting tool 50 (also known as a cutter) for a mechanical excavator. This cutting tool 50 includes two main elements: a cutting head 51 and a solid insert called a cutting tip 10, which is located on the front end 52 of this cutting head 51. The cutting tip 10 is firmly fixed to the front end 52 of the cutting head 51 so that it can perceive those significant efforts that the cutter is exposed to during operation. The cutting tip may be brazed to the cutting head, and it may also include a protrusion or recess, which is placed in the corresponding recess of the cutting head or protrusion in the cutting head. Other attachment or fitting options may also be used, including removable mechanical fasteners that are within the scope of this description.

The cutting tool 50 includes a central axis Cb and is substantially symmetrical about this axis. In operation, this cutting tool 50 is attached to the holder of the cutter with the possibility of rotation around the axis Cb, which provides a more uniform wear of the cutting tip 10.

The cutting head 51 includes an enlarged head portion on which the cutting tip is mounted, and a cylindrical shank 54, which extends back from the proximal end 55 of the head 53. This shank 54, having a typical shape, is mounted in the holder of the cutter, excavator in such a way as to prevent axial move the cutter 50, but at the same time allow it to rotate around the axis Cb of this cutter.

When used, a plurality of cutters 50 are typically inserted into the respective cutter holders that are mounted on the rotating drum of the excavator. These cutters 50 extend from the drum to the outside, and when the drum rotates, it moves along the surface of the rock in the cutting direction. Thus, the cutters cut into the surface of the rock at an angle (usually referred to as the angle of inclination), and when impacted on the rock, the cutter is usually oriented as shown schematically in FIG. 6. In FIG. 6, the inclination angle α is less than 90 °, usually of the order of 55 °, while the rake angle β depends on the taper angle σ and the inclination angle α. In the embodiment shown, since the taper angle σ of the cutting tip is large, the rake angle β is negative (that is, it extends beyond a line perpendicular to the surface of the rock). Although a negative rake angle is not important for the present invention, it is favorable because it improves the efficiency of the cutter.

In more detail, the shape of the cutting tip 10 is shown in FIG. 2-4. In general, the cutting tip 10 includes a tip body 11 having a pointed distal end 12 and a wider proximal end 13. The pointed distal end 12 is located on the central axis Cb of the cutting tip, which during operation coincides with the central axis Cb of the cutting tip, as shown in FIG. 1. In one embodiment, the distal end 12 is substantially hemispherical and has a tip radius η of 0.2 to 5 mm.

The cutting tip 10 also includes a wall 14, which diverges outward from the distal end 12 to the proximal end 13. In contrast to the prior art point impact tools that produce uniform force during a dynamic impact on the rock with a cutting tip, this wall has a special a profile in order to have an uneven force effect, which upon impact contributes to the appearance of radial cracks in the material being processed. As shown in FIG. 2 of the embodiment, the cutting tip wall 14 has such a profile as to include a plurality of axially extending ribs 15,

- 3 016278 which extend from the proximal end to the distal end, and a plurality of intermediate regions 16 that are located between the ribs. As best shown in FIG. 3 and 4, the proximal end 13 of the cutting tip 10 approaches a square in shape (with or without rounding) with ribs 15 extending from the end angles of this square to the pointed distal end 12. In this case, the cutting tip as such includes four ribs 15 and four intermediate regions 16 and has a tip shape, somewhat similar to a pyramid with a square base. The profile of the rib may be different depending on the pointedness, but usually it has a radius of curvature r ₂ from 0.1 to 20 mm. With this design, the intermediate regions 16 form discontinuous surfaces of the tip body 14. These surfaces are mutually inclined, and the ribs 15 form angles between adjacent surfaces. Furthermore, although these intermediate regions are substantially planar, they may not be planar, but rather curved and arched in the region from the proximal end 13 to the distal end, as best seen in the section in FIG. 2.

In this case, the amount of bending of the intermediate regions 16 affects the resulting rake angle of the cutter, as shown in FIG. 6. In the embodiment shown, the intermediate regions are convex to provide a taper angle at the distal end of 120 to 140 °. This provides the tip of this shape with a strong top. However, the geometric shape of the cutting tip can be such that its taper angle has a wider range of indicators than the specified limit, and can usually vary from 30 to 170 °. As well as the taper angle of the cutting tip can vary along the intermediate regions to the proximal end. In the shown embodiment, the intermediate regions have a second taper angle near the proximal end of the tip body, which is smaller than the taper angle at the distal end to allow for removal of the cutter and, therefore, minimize wear during cutting.

Although in the embodiment shown, the intermediate regions are generally convex, since they are selected towards the distal end, in an alternative embodiment, these regions may be curved inward to be concave in this direction. In addition, these concave regions may extend across the width of each region, or they may occupy only a certain portion (usually the middle portion) of this region.

In addition, the ribs can be arranged so as to repeat the profile of the intermediate regions, and in the shown embodiment, the ribs 15 repeat the convexity of the intermediate regions 16 when they bend to the distal end 12. However, by changing the height of these ribs along their length, these ribs can be differently oriented relative to the intermediate regions, and, accordingly, they can pass in a straight line, can be convex or concave, regardless of the configuration of the existing intermediate regions (that is, regardless of whether these areas are flat, concave or convex). This provides more opportunities for optimizing the shape of the cutting tip relative to its contribution to the cracking process and to obtain effective cutting surfaces and good wear resistance.

In addition, in the shown embodiment, the cutting tip 10 includes a connecting element 17 that extends outward from the proximal end 13 of the tip body 11 (FIG. 2). In the shown embodiment, this connecting element has the shape of a shortened shank, which is cylindrical and configured to be located in a corresponding recess in the front end 52 of the housing of the head 51 of the cutting tool. It should be understood that the design of the connecting element may take other forms known to specialists in this field of technology.

When using a tip of such a geometric shape that includes ribs 15, the load profile of the impacted material is not uniform, namely, the ribs of the tip are designed to act on the processed material with a greater load than the load exerted by the intermediate regions. Such a higher concentration of load, in turn, contributes to radial cracking of this material rather than circular cracking, which prevails when using conventional conical tips. An example of such predominant radial cracking is shown in FIG. 7, where the tip having the geometric shape shown in FIG. 2, a dynamic blow was struck on the brittle material 100, causing radial cracks 101. This advantage of the possibility of changing the nature of cracking contributes to the removal of larger fragments of the material, as well as less dust formation due to the reduction of circular cracking. In addition, a tip of the geometric shape shown in FIG. 2, crushes less material than a conventional conical tip, and also consumes less energy and is less noisy and more wear resistant.

Although the geometric shape of the tip shown in FIG. 1-4, has essentially a base in the form of a square, it is allowed to use tips and other configurations that have a positively assessed ability to change the nature of cracking, as indicated above. For example, in FIG. 5 shows an embodiment in which the cutter 60 includes a cutting tip 10 having a geometric shape including a pentagonal base, which means it has five ribs, and not four, as in the embodiment described above.

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In the following claims and in the above description of the present invention, everywhere, except where the context implies a different meaning, the word contain or its forms, such as contains or containing is used with the meaning to include, that is, to clarify the presence of the above features, not to exclude the presence or addition of additional features in various embodiments of the present invention.

Changes and / or additions may be made to the above parts of the present invention without departing from the scope and essence of the present invention.

Claims (20)

CLAIM 1. The cutting tip of a mechanical excavator comprising a body having a substantially pointed distal end, a proximal end located at a distance from the distal end, and a wall that diverges outward from the distal end to the proximal end, the wall having such a profile that have an uneven load distribution on the material subjected to the impact of the cutting tip to facilitate the formation of radial cracks in this material, and the wall has such a profile to include a lot of stretch axially extending ribs and intermediate regions located between the ribs, while adjacent intermediate regions are mutually inclined, and ribs located between mutually inclined intermediate regions form the edges of the tip body, which are positioned so as to cause a more concentrated load in the impact material than the load caused by the intermediate regions. 2. The tip according to claim 1, in which the ribs extend to the far end of the body of the tip. 3. The tip according to claim 1 or 2, in which at least one of the intermediate regions is substantially flat in at least one portion of this region. 4. The tip according to any one of claims 1 to 3, in which at least one of the intermediate regions is arcuate, and each of the ribs has a radius of curvature that is significantly less than the corresponding radius of curvature of the specified or each arcuate intermediate region. 5. The tip according to any one of claims 1 to 4, in which the ribs have a radius of curvature from 0.1 to 20 mm. 6. The tip according to claim 4 or 5, in which at least one of the intermediate regions is convex in at least one portion of this region. 7. A tip according to any one of claims 4 to 6, in which at least one of the intermediate regions is concave in at least one portion of this region. 8. The tip according to any one of claims 1 to 7, in which the body of the tip has at least three ribs. 9. The tip according to any one of claims 1 to 8, in which the proximal end of the tip body is polygonal, and the ribs extend from the angles of the proximal end. 10. The tip according to any one of claims 1 to 9, in which the wall of the body of the tip diverges outward to the proximal end and has a taper angle at the distal end from 30 to 170 °. 11. The tip according to any one of claims 1 to 10, in which the distal end has a tip radius of 0.2 to 5 mm. 12. The tip according to any one of claims 1 to 11, configured to rotate around an axis. 13. The tip according to item 12, in which the axis of rotation passes through the far end. 14. The tip according to any one of claims 1 to 13, further comprising a connecting element located at the proximal end of the tip body and configured to install the cutting tip in the head of the cutting tool. 15. The tip according to 14, in which the connecting element is made in the form of a protrusion made with the possibility of placement in a corresponding recess in the head of the cutting tool. 16. The tip according to 14, in which the connecting element is made in the form of a recess made with the possibility of placement in the corresponding protrusion in the head of the cutting tool. 17. A cutting tool comprising a head housing having a front end and a cutting tip according to any one of claims 1-16, located at the front end. 18. The tool according to 17, in which the cutting tip is mounted on the head housing and is made of a harder material than the head housing. 19. The tool according to 17 or 18, in which it is made to rotate around its axis. 20. The tool according to claim 19, in which the axis of the tool passes through the far end of the cutting tip.