RU2671386C2 - Percussive drill bit with multiple sets of front cutting inserts - Google Patents

Abstract

FIELD: soil or rock drilling; mining.SUBSTANCE: group of inventions relates to a percussive drill bit for a rock and a percussive drill device comprising said bit. Percussive drill bit comprises a head provided at one end of an elongate shank. Head has a forward-facing front surface bounded by a peripheral edge. Percussive drill bit also comprises a plurality of end cutting inserts distributed on the front surface in various radial positions between the central axis extending through the drill bit and the peripheral edge of the front surface. First inner set of cutting inserts is arranged radially innermost on or towards the axis. Calibration inserts are arranged on or towards the peripheral edge. Additional end cutting inserts are grouped into multiple sets. Each set is arranged between the radially innermost set and the calibration group, comprises the same number of inserts and is placed at a different radial distance from the axis. Each insert of each respective set is placed at the same radial distance. Each insert of each set is placed circumferentially between a pair of inserts of an adjacent radially inner and / or radially outer set so that the positions of the inserts of adjacent sets are staggered around the circle. Angular separation between adjacent inserts in a set is the same for all inserts. Diameter of the inserts in at least one set is larger than the diameter of the inserts in the corresponding radially inner set and / or radially the innermost group of inserts.EFFECT: technical result is higher penetration rate and longer bit life.12 cl, 4 dwg

Description

FIELD OF THE INVENTION

The present invention relates to a rock drill bit and, in particular, although not exclusively, to a drill bit formed with a cutting head on which a plurality of end cutting inserts are placed in sets, each set distributed in different radial positions on the front surface of the cutting head.

BACKGROUND

Impact drill bits are widely used for drilling relatively shallow wells in hard rock and for creating deep wells. For the latter application, drillstrings are commonly used in which a plurality of rods are interconnected to advance the drill bit and increase the depth of the well. In “drilling with the upper hammer”, the ground machine is capable of transmitting the combined impact and rotational movement of the drive to the upper end of the drill string, while the drill bit located at the lower end is capable of crushing the rock and forming wells. When “drilling with a submersible hammer”, the impact is transmitted not through the upper end of the drill string, but with the help of a hammer directly connected to the drill bit inside the well.

A drill bit typically comprises a drill head onto which a plurality of solid cutting inserts, commonly called pins, are mounted. Such pins contain carbide-based material to extend the life of the drill bit. Traditionally, a drill bit comprises a plurality of calibration pins distributed around a circumference on the outer periphery of the head, which is adapted to engage the material being crushed and determine the diameter of the well. A plurality of end pins are also mounted on the head, provided on the front surface of the head to engage the material being crushed in the most axially drilling area. Exemplary percussion drill bits are disclosed in US 3,357,507; US 3,388,756; US 3,955,635; US 2008/0087473; US 2008/0078584; WO 2012/17460; WO 2006/033606; WO 2009/067073; US 7,527,110; US 7,392,863; EP 2592216; WO 2012/038428 and EP 2383420.

Typically, the cutting inserts are distributed on the front surface in sets or, as it seems, randomly in different places, and not on a common circumferential line. Typically, the variety of inserts increases gradually from a radially inner to a radially outer region of the front surface. In order for the bit to move into the rock during drilling, each insert must crush the rock in its circumferential line. When a particular area of the front surface includes one insert, a full 360 ° revolution is necessary to advance the bit axially forward. Accordingly, inserts in these areas of the bit with fewer adjacent inserts have a higher wear rate and also limit the rate of penetration of the bit. Accordingly, a drill bit is required that solves these problems.

SUMMARY OF THE INVENTION

The main objective of the present invention is the provision of an impact drill bit, which is configured to maximize the rate of penetration into the rock during drilling and maximize the life of the bit as much as possible.

An additional specific goal is to ensure the distribution of hardened cutting inserts on the head of the drill bit, which is optimized to withstand frictional wear sequentially in different radial positions from the axial center of the bit. An additional specific goal is to make end pins with the ability to maximize drilling speed by organizing and distributing them on the front surface relative to the axis of the bit and the peripheral edge of the drill bit head.

According to a first aspect of the present invention, there is provided a rock drill bit comprising: a head provided at one end of an elongated shank, the head having a forward facing surface defined by a peripheral edge; a plurality of end cutting inserts distributed on the front surface at different radial positions between the central axis extending through the drill bit and the peripheral edge of the front surface; moreover, the end cutting inserts are grouped into many sets, each set containing the same number of inserts and placed at a different radial distance from the axis, and each insert of each respective set is placed at essentially the same radial distance, characterized in that: each insert of each set is placed on a circle between a pair of inserts of an adjacent radially external and / or radially internal set so that the positions of the inserts of adjacent sets are staggered around the circumference.

The reference in this description to the “cutting insert” encompasses alternative and equivalent expressions, such as cutting pins and the like, specially adapted to have a hardness that is greater than the hardness of the main body of the bit.

The reference in this description to “each insert of each respective set placed at substantially the same radial distance” encompasses the axial centers of each of the inserts in each set placed on the same circumferential line and at the same radial separation distance from the axis. This expression also encompasses the axial centers of at least some of the inserts in each respective set placed radially outside or inside relative to other inserts in the same set. This option includes positioning the axial center of one or more inserts in the set so that it (s) is eccentric (s) (offset) relative to other inserts in the same set by up to the diameter (D) , radius, a third of the diameter (D / 3) or a quarter of the diameter (D / 4) of the inserts in the set.

The reference in this description to the "angular distance" covers the angle between the inserts and, in particular, the angle between adjacent inserts in the circumferential direction.

Finding the positions of adjacent sets of inserts in a checkerboard pattern around the circumference is preferred for several reasons. Firstly, by positioning the inserts of one set in a circle between the inserts of an adjacent radially external and / or radially internal set, the diameters of the inserts of the neighboring sets can overlap radially to provide a more compact design. This design also maximizes the number of inserts that can be inserted into the front surface. Additionally, positioning the inserts of the various sets so that they are circumferentially offset relative to each other provides a more efficient and effective cutting action at the bottom of the borehole. In particular, this design proved to be more effective for the destruction of the rock, since the cut grooves created in the rock overlap, which contributes to chipping or fragmentation of the rock, driven radially outward along the cutting surface.

Each set may contain from three to six cutting inserts. Preferably, each set contains four inserts. This design represents an optimal compromise between minimizing wear on the inserts, as well as minimizing the total weight of the cutting bit, which naturally increases with a large number of inserts.

Preferably, each set contains from two to eight sets of end cutting inserts. Perhaps the chisel contains four sets of inserts. Perhaps the inner set of inserts is the radially innermost set of end pins. Perhaps the drill bit contains an additional set of the innermost end pins, which contains a number of cutting inserts less than the number of inserts in the radially external sets (each of these radially external sets contains the same number of cutting inserts in accordance with the object of the invention). An additional set of innermost inserts having a lower number of inserts relative to the radially outer sets may be preferred for use with smaller drill bit heads.

Perhaps the diameter of the inserts of each set increases in the direction radially outward from the axis. Alternatively, the diameter of the inserts in all or some of the kits may be substantially the same. Such configurations are appropriate to maximize the life of the drill bit, taking into account the different angular speeds of the inserts in different sets. That is, radially outer sets may include inserts of larger diameter relative to the inner sets to compensate for the increased angular velocity during drilling so as to ensure uniform wear rate of the inserts in all sets.

It is possible that the central region of the front surface is axially in front of the peripheral edge. It is possible that the front surface is generally convex so that the central region of the front surface is axially in front of the peripheral edge. The front surface can be domed, that is, tilted axially rearward towards the shank so that the radially innermost part of the front surface is axially in front of the peripheral edge of the head. According to additional embodiments, the front axially located region of the head may be substantially planar or flat, or may comprise a cavity so as to be generally concave, having a peripheral sleeve that projects axially forward from the radially innermost region into which the plurality of sets of inserts are mounted. In some embodiments, the annular head sleeve may comprise one or a plurality of sets of end pins in addition to calibration pins.

Preferably, the head and shank are integrally formed. This design is preferred in order to provide a strong and reliable bit made with the ability to withstand significant torque and axial forces transmitted during hammer drilling. Additionally, the head of the bit is formed as an integral component made in one piece with the elongated shaft to optimize the strength of the bit to provide a rigid bit that is not susceptible to the independent movement of individual components, which is otherwise disadvantageous with multi-component bits.

Preferably, the front surface is formed as a single and common support base for the inserts so that all the inserts are inserted into a single common surface. This design is preferred for distributing the load forces evenly on the front surface to maximize the life of the bit and minimize wear. The inserts are inserted directly into the bit head through the front surface, and are not installed through an intermediate and removable housing. This design is preferred in order to provide a structurally robust configuration such that the inserts are resistant to the torque and axial forces arising during use.

Preferably, the angle between adjacent inserts in each respective set is substantially the same. That is, the separating distance between adjacent inserts in a circumferential direction around a central axis in each set is substantially the same. Preferably, the angle between adjacent inserts (in each set) is substantially the same for all sets on the front surface. Preferably, the circumferential distance between adjacent inserts in each set increases between sets in a direction radially outward from the central axis. As will be understood, the increase in the circumferential separating distance between the inserts in the sets in the direction gradually outward from the axis is a consequence of uniform angular spacing between adjacent inserts in all sets.

It is possible that the positions of the inserts of at least two sets overlap radially. Perhaps the positions of the inserts of three, four, five, six, or all sets overlap radially. Optionally, the radially inner, radially outer, and / or radially middle sets contain inserts that are arranged so as to radially overlap. This configuration optimizes the cutting efficiency of the bit head and maximizes the penetration rate, since the distribution density of the cut grooves in the rock increases, since at least some of the formed grooves overlap radially.

Optionally, the drill bit may comprise a first inner set located radially at the innermost on or in the direction of the axis relative to the other sets; and a first intermediate set, placed radially between the first internal set and the calibration group of cutting inserts placed on or towards the peripheral edge. Optionally, the drill bit may further comprise a second intermediate set located radially between the first intermediate set and the calibration group. Optionally, the drill bit may further comprise a second inner set located radially between the first internal set and the first intermediate set. This design is appropriate to maximize the drilling speed and the life of the drill bit, made with a domed or convex front surface. As will be understood, the number of different sets of inserts may vary in accordance with the size, geometry and profile of the shape of the bit head, including, in particular, a flat and concave region of the front surface.

According to a second aspect of the present invention, there is provided an impact drilling apparatus comprising a drill bit as claimed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

A specific embodiment of the present invention will now be described solely by way of example and with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a drill bit containing a plurality of end cutting inserts distributed and placed in groups or sets on the head of the bit according to a particular embodiment of the present invention;

Figure 2 is an additional perspective view of the head of the drill bit in Figure 1;

Figure 3 is a top view of the front surface of the head in Figure 2;

Figure 4 is a side view of the head in Figure 2.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

In Figures 1-4, the drill bit 100 comprises a drill bit 101 formed at one end of a generally elongated shaft 102, both the head 101 and the shaft 102 being centered on the longitudinal axis 108. The shaft 102 comprises splines 109 for engagement with corresponding splines of the drive tool (not shown) that surrounds the shaft 102 during use. The head 101 comprises an axially front section 111 and an axially rear section 110 of the skirt, which cooperates with the shaft 102. Section 111 has a larger diameter than the skirt 110 and is partially bounded by an annular outermost peripheral edge 106. The forward-facing front surface, generally indicated by 105 protrudes axially forward from the edge 106 so that the forward-facing part of section 111 is generally convex and has a dome-shaped profile when viewed from the side or in cross section. The front head section 111 tapers back from the edge 106 through a short, longitudinally extending back surface 107 that mates with the axially front region of the skirt 110.

The front surface 105 can be considered as radially segmented into a plurality of annular regions extending between the axis 108 and the peripheral edge 106. In particular, the surface 105 comprises an outer peripheral region 200, which is bounded along its periphery by the edge 106. The region 200 is chamfered to converge backward relative to axis 108 so as to be deflected relative to the radially innermost region 203, which is aligned substantially perpendicular to axis 108. Region 203 is axially raised to form platform 204 which projects upward from the first intermediate region 202. The region 202 is also aligned substantially perpendicular to the axis 108. The first intermediate region 202 is surrounded by a second intermediate region 201, which is beveled to converge backward about the axis 108. The second intermediate region 201 is radially between the first intermediate region 202 and peripheral region 200. The deviation angle with which region 201 extends from axis 108 is less than the corresponding angle with which peripheral region 200 extends relative to axis 108. C respectively and, as indicated in Figure 4, the regions 200-203 together form a generally convex front surface 105 that projects axially forward from the peripheral edge 106.

A plurality of hardened cutting inserts are mounted on the head 101, indicated generally by 103 and 104 made of carbide-based material such as cemented carbide or tungsten carbide, for example. According to a particular embodiment, the inserts 103, 104 are generally domed. However, in accordance with further specific embodiments, the inserts 103, 104 may have cutting tips axially in front that are rounded, conical, bullet-shaped, hemispherical, flat, or pointed in accordance with the conventional configuration of the cutting inserts. The inserts 103, 104 are inserted into the head section 111 so as to axially protrude from the front surface 105. As will be appreciated, the calibration inserts 103 are placed on or towards the peripheral edge 106 to determine and maintain a predetermined well diameter during formation. The calibration inserts 103 are inclined radially outward so as to be generally inclined and facing outward from the axis 108 in accordance with the peripheral region 200.

In Figures 2 and 3, the inserts 104, which are arranged radially inside the calibration inserts 103, are grouped into a plurality of sets, each set being placed at a different radial distance from the axis 108. Additionally, each insert 104 of each set is placed at the same radial separating distance from the axis 108 so that the inserts 104 of each set are placed on a common circumferential line about an axis 108.

According to a specific embodiment, the inserts 104 are divided into a first inner set 205, arranged radially innermost on or towards the axis 108 and installed within the inner region 203. A second inner set 206 surrounds the first set 205 and is installed in the region 202. The first intermediate set 207 surrounds the second inner set 206 and is installed in area 201. The second intermediate set 208 (also installed in area 201) is placed radially outside the first intermediate set 207 and radially inside the calibration group x inserts 103. Preferably, to maximize the life and maximize the rate of penetration of 100 bits, each set 205-208 includes the same number of inserts 104 constituting four insertion set according to the present embodiment. Accordingly, during the rotation of the bit 100 about the axis 108, each insert 104 of each set is configured to jointly form an annular cutting line when the bit 100 is rotated 90 ° during drilling. This should be contrasted with traditional designs, where, for example, the innermost set 205 contains one insert 104, which requires 360 ° rotation to complete one ring-shaped cutting line in the rock. As will be understood, the penetration rate of the present bit 100 is substantially greater than that of traditional designs, and the wear of the inserts is lower and more evenly distributed.

The first and second intermediate sets 207, 208 comprise inserts 104 having axes that are inclined to converge radially outward from the axis 108 in accordance with the angular orientation of the region 201 (relative to axis 108) within which the sets 207, 208 are mounted. For comparison, the inserts 104 in the first and second inner sets 205, 206 have axes that are aligned substantially parallel with the axis 108. As illustrated in Figure 4, the angle with which the inserts 104 of the first and second intermediate sets 207, 208 extend radially outward axis 108, less than the corresponding angle with which the calibration inserts 103 are inclined radially outward from axis 108.

In Figure 3, each insert 104 of the first inner set 205 is separated from the axis 108 by the same radial separation distance R1. Each insert 104 of the second inner set 206 is separated from the axis 108 by the same radial separation distance R2. Each insert 104 of the first intermediate set 207 is separated from the axis 108 by the same radial separation distance R3. Each insert 104 of the second intermediate set 208 is separated from the axis 108 by the same radial separation distance R4. According to the present embodiment, R1 <R2 <R3 <R4. However, the magnitude of the sequential increase from R1 to R4 (via R2 and R3) is not uniform according to the present embodiment.

According to the present embodiment, the angle at which adjacent inserts 104 (adjacent in the circumferential direction) are spaced apart is 90 ° in all sets 205-208. That is, the angle between adjacent inserts 104 of each set is constant and the same in all sets 205-208. Such a configuration is preferred in that the inserts wear sequentially in different radial positions from the axial center of the bit, and the penetration rate of the bit is maximized.

In Figure 3, the position of each set of inserts 205-208 is staggered around the circumference on the front surface 105. That is, each insert 104 of each set 205-208 is placed circumferentially between two inserts 104 of the adjacent radially inner or radially outer set 205-208. In particular, each insert 104 of the set 205 is arranged circumferentially between the inserts 104 of the set 206; inserts 104 of the set 206 are placed around the circumference between the inserts 104 of the sets 205 and 207; the inserts of the set 207 are placed around the circumference between the inserts 104 of the sets 206 and 208, and the inserts 104 of the set 208 are placed around the circumference between the inserts 104 of the set 207. According to a specific embodiment, the inserts 104 of the set 208 are also placed around the circumference between the calibration inserts 103. Additionally and when considering a top view, as illustrated in Figure 3, the respective diameters of the inserts 104 of at least some of the sets overlap radially, and this is possible due to the staggered arrangement around the circumference of the inserts with neighboring sets. In particular, the diameters of the inserts 104 of the sets 207 and 208 overlap radially. Also, as follows from Figure 3, each insert 104 of each set is placed approximately in the middle around the circumference between a pair of inserts 104 of the adjacent set. With this configuration, the inserts of all the sets are spaced so as to be placed as far as possible from each other on the front surface 105. This design is preferred in order to maximize the cutting efficiency of each insert and provide a structurally robust bit. The staggered circumference of the inserts and the radial overlap between the inserts 104 of the sets 207, 208 are further preferred to provide a radially compact head 101 and to maximize the number of sets 205-208 inserted into the front surface 105. The present configuration is capable of actively destroying the rock at the bottom of the borehole, partly due to the partial radial overlap of the sets 207, 208 and the grouping of the inserts 104 into sets (206, 208) placed on different radial x distances from axis 108.

Installing the first inner set 205 on the platform 204 is preferred to allow for drilling when the inserts of the set 205 meet the rock initially during drilling. This design is also considered appropriate to increase the penetration rate by providing a local "lower" level in the rock, in which cracks can form during drilling. Additionally, a raised or convex front surface 105 having a raised innermost region 203 is useful in order to minimize the risk of cracks in the head 101 starting from flushing holes 112 extending inside the head 101.

According to the present embodiment, the diameter of the inserts 104 of the first inner set 205 is smaller than the corresponding diameter of the second inner set 206. Similarly, the diameter of the inserts 104 of the first and second inner sets 205, 206 is smaller than the corresponding diameter of the inserts 104 of the first and second intermediate sets 207, 208. As shown and according to the present embodiment, the diameter of the calibration inserts 103 is larger than the diameter of each of the inner and intermediate inserts 104 of sets 205-208. However, according to additional embodiments, the diameter of the inserts 104 in all kits 205-208 may be substantially equal to or may be smaller or larger than the diameter of the calibration inserts 103.

According to additional embodiments, the axially forward-facing region of the head section 111 may be substantially planar (flat) or may include a concave region defined by an axially-extending peripheral sleeve. Additionally, the head 101 may include peripheral axially extending flushing channels associated with each flushing hole 112 to facilitate axially moving back the flushing fluid and fragments and small rock particles.

Additionally, according to additional embodiments, the head 101 may comprise an additional innermost set of inserts 104 located radially inside the set 205, containing the same or fewer inserts (in the same and general radial position) relative to the radially external sets 205-208. That is, the innermost set of inserts 104 may contain one, two or three inserts 104, while the radially outer sets 205-208 may contain four or more inserts, the inserts 104 of each set being placed at the same radial separation distance R1-R4 relative to the axis 108.

Claims (21)

1. An impact drill bit (100) for a rock, comprising: a head (101) provided at one end of the elongated shank (102), the head (101) having a forward facing surface (105) facing forward defined by a peripheral edge (106); a plurality of end cutting inserts (104) distributed on the front surface (105) in different radial positions between the central axis (108) extending through the drill bit and the peripheral edge (106) of the front surface (105), wherein the first inner set (205) of cutting inserts (104) is located radially the innermost on or towards the axis; calibration inserts (103) are placed on or towards the peripheral edge 106, moreover, additional end cutting inserts (104) are grouped into many sets (206-208), and each set (206-208) is placed between the radially innermost set (205) and the calibration group (103), contains the same number of inserts (104) and placed at a different radial distance from the axis (108), and each insert (104) of each respective set (206-208) is placed at essentially the same radial distance; each insert (104) of each set (206-208) is placed around the circumference between a pair of inserts (104) of the adjacent radially external and / or radially internal set so that the positions of the inserts (104) of the neighboring sets (206-208) are in a checkerboard pattern circumferential order the angular spacing between adjacent inserts (104) in the set (206-208) is essentially the same for all inserts (104), characterized in that the diameter of the inserts (104) in at least one set is larger than the diameter of the inserts in the corresponding radially inner set and / or radially the innermost group of inserts (205). 2. The drill bit according to claim 1, in which each set (206-208) contains from three to six inserts (104). 3. The drill bit according to claim 2, in which each set (206-208) contains four inserts (104). 4. A drill bit according to claim 1 or 2, comprising from two to eight sets (206-208) of end cutting inserts (104). 5. A drill bit according to claim 1 or 2, in which the central region (203) of the front surface (105) is axially positioned in front of the peripheral edge (106). 6. A drill bit according to claim 1 or 2, wherein the front surface (105) is generally convex so that the central region (203) of the front surface (105) is axially in front of the peripheral edge (106). 7. A drill bit according to claim 1 or 2, wherein the innermost set (205) contains the same number of inserts (104) as the radially outer sets (206-208). 8. A drill bit according to claim 1 or 2, containing the radially innermost group (205) of end inserts (104), which contains the number of inserts (104), less than the number of inserts (104) in each of the sets (206-208), which placed radially outside the sets (206-208). 9. The drill bit according to claim 1 or 2, in which the sets (206-208) contain: a first intermediate set (207) and a second intermediate set (208) placed radially between the first intermediate set (207) and the calibration group (103). 10. A drill bit according to claim 9, further comprising an inner set (206) placed radially between the innermost group of inserts (205) and the first intermediate set (207). 11. The drill bit according to claim 10, in which the innermost set (205) is placed the most protruding axially forward, the second intermediate set (208) is placed the most protruding axially back from the sets (206-208), and the calibration group (103) is placed axially behind the second intermediate set (208). 12. An impact drilling device comprising a drill bit (100) according to any preceding claim.

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