KR20210049810A - Drill bit with curved sludge grooves - Google Patents

Abstract

The present invention relates to a percussive drill bit having a head and an axial rear skirt. The plurality of ribs protrude radially outward from the skirt and define longitudinally extending channels. The ribs and channels are curved or angled in the longitudinal direction away from the longitudinal axis of the drill bit to facilitate rear transport of fines and flushing fluid.

Description

Drill bit with curved sludge grooves

The present invention relates to a rock drill bit having a head and an axial rear skirt, in particular but not exclusively, to a percussion rock drill bit, wherein longitudinal ribs along the skirt protrude radially outwardly and cut rock and fluid Defines the sludge channels configured for the axial rear transport of the vehicle.

Percussive drill bits are widely used to drill relatively shallow bores in hard rock and also to create deep boreholes. In the latter application, since the depth of the bore increases, a drill string in which a plurality of rods are connected end to end through a threaded joint is commonly used. While the drill bit located at the lower end operates to crush the rock to form a borehole, the terrestrial machine operates to transmit a combined impact and rotary drive motion to the upper end of the drill string. WO 2006/033606 discloses a typical drill bit comprising a drill head equipped with a plurality of hard coated inserts, commonly referred to as buttons. These buttons contain a carbide-based material to improve the life of the drill bit.

The fluid is typically flushed through the drill string and discharged from the base of the borehole through openings in the drill head and flushes the rock cut from the boring area to be transported back from the outer periphery of the drill string.

The effectiveness of a drill bit for drilling holes in rock depends on the rear transport of rock debris in the cutting area. The cut rock combined with the flushing fluid typically forms sludge, and it is important that the sludge is transported backwards during cutting in order to prevent regrinding of the rock and the corresponding shortening of the operating life of the drill bit. In addition, the untransported sludge serves to block the bore and inhibit the axial rear extraction of the drill bit, increasing the risk of possible collapse of the borehole during bit extraction. Therefore, there is a need for a drill bit to solve this problem.

It is an object of the present invention to provide a drill bit and in particular a percussive rock drill bit which facilitates the axial rear transport of a flushing fluid and cut rock, usually in the form of sludge, from the front cutting area of the borehole.

A further object is to provide a drill bit that minimizes unnecessary regrinding or grinding of rock debris in order to extend the working life of the drill bit.

Another further object is to provide a drill bit to facilitate rear extraction after forward drilling and to prevent borehole collapse when the drill string and drill bit are extracted rearward.

The objectives are drills with a skirt extending axially rearward from the cutting head containing sludge grooves specially adapted for the axial rearward transport of rock debris and flushing fluid during axial forward drilling and axial rear extraction of the drill bit. It is achieved by providing a bit. The sludge grooves in the skirt extend axially bent or curved relative to the longitudinal axis of the drill bit so as to align obliquely with respect to the longitudinal axis in the longitudinal direction of the ribs between the bit head and the axially rearmost portion of the skirt. It is defined by the ribs. That is, the ribs defining the sludge grooves (referred to herein as channels) have a length component that may be considered deflected to deviate circumferentially about an axis. Optionally, the longitudinal path of the ribs and channels may be helical around the axis.

According to a first aspect of the present invention, a drill bit is provided, the drill bit comprising: a head having cutting elements for abrasion of rock by rotation of a given bit about a longitudinal axis; A skirt extending axially rearward from the head; A plurality of ribs protruding radially outwardly and extending axially along the skirt to define channels extending in the axial direction, each of the ribs and channels extending axially in the direction between the head and the axial rear end of the skirt Including the plurality of ribs having a length that is equal to; It is characterized in that at least a portion of the ribs and channels is bent or curved in the longitudinal direction such that the longitudinal portion of the ribs or channels is oblique to the longitudinal axis.

The ribs and channels comprise a corresponding width aligned circumferentially and a depth extending radially. The width and depth may or may not be uniform along the length of the ribs and channels. However, with any change in width and depth, the longitudinal path of the ribs and channels along the skirt in the direction between the head and the axial rearmost part of the skirt is not parallel, i.e. at least to some extent in the circumferential direction about the axis. It is angled about the longitudinal axis to extend.

Reference herein to ribs or channels that are oblique to the longitudinal axis includes alignment of ribs and channels that are not parallel to the bit longitudinal axis over at least a portion of their length. The orientation of the ribs or channels with respect to the axis includes a general orientation in which each rib is generally defined by a leading face, a leading edge, a land face, a trailing edge and a trailing face. These faces and edges may be straight or curved, but importantly, at least some or all of them (over at least a portion of each axial length) are aligned non-parallel to the longitudinal axis.

Optionally, some of the ribs and channels oblique to the longitudinal axis are located in the axial rear portion of the skirt. Optionally, the axial front portion of the ribs and channels are generally aligned parallel to the longitudinal axis. The linear axial front portion is effective in providing immediate rear transport of the cut rock and flushing fluid, while the obliquely aligned axial rear portion of the ribs and channels allows the sludge from the drill bit to the rear across the outer surface of the drill string. It is effective to follow a spiral or vortex flow path.

Optionally, the axial rear portion is 20%, 30%, 40%, 50%, 60%, 70%, 80% or 90 of the length of the skirt between the axially rearmost region of the head and the axially rear end of the skirt. It extends to %. Preferably the axial rear portion extends over most of the length of the skirt. Preferably the axial rear portion spans 30 to 80%, 40 to 80%, 50 to 80%, or 50 to 70% of the length of the skirt between the axial rearmost region of the head and the axial rear end of the skirt. Is extended.

Optionally, the longitudinal portion of the ribs and channels is at least partially helical around the axis. This alignment is effective in providing a non-linear flow of sludge axially rearward along the borehole and preventing the drill bit from sticking during extraction.

Preferably, each rib comprises a leading end surface and a rear end surface separated by a land surface facing outward in a radial direction, the leading end surface and the rear end surface at least partially defining the channels. The transition from the leading end face to the back end face within any one channel may be curved continuously over the trough region of each channel.

Preferably, it is bent or bent in the same circumferential direction about the axis such that both the leading end surface and the rear end surface of the ribs in the longitudinal direction are aligned obliquely with respect to the longitudinal axis. This arrangement is effective in properly channeling the cut rock and flushing fluid, which may be considered a helical or vortex flow path across the outer surface of the drill string.

Preferably, in the longitudinal direction, it is bent or curved so that at least a portion of the leading edge and trailing edge of the ribs at the junction between the land face and the respective leading and trailing faces are aligned obliquely with respect to the longitudinal axis. Preferably, the leading edge and a portion of the trailing edge oblique to the longitudinal axis are located in the axial rear portion of the skirt.

Preferably, in a cross section perpendicular to the longitudinal axis, the leading section is aligned generally perpendicular to the direction of rotation of the bit about the longitudinal axis. This configuration is useful for directing the flow of sludge in the circumferential direction (approximately helical flow path) within the bore. Optionally, in a cross section perpendicular to the longitudinal axis, the rear section is aligned transversely to the direction of rotation of the drill bit and/or obliquely to the leading section.

Optionally, the angle at which the ribs bend or bend so that their length deviates in the circumferential direction is 1 to 20°, 1 to 18°, 1 to 16°, 1 to 14°, 1 to 12°, 2 with respect to the longitudinal axis. It is in the range of ~ 12°, 3 ~ 10°, 3 ~ 8°, or 4 ~ 6°. The oblique alignment of these ribs is effective in preventing the drill bit from sticking during extraction by properly directing the cut rock and flushing fluid axially rearward away from the drill bit. Preferably, the drill bit comprises an inner bore and passages extending axially from the front end of the bore to appear as openings in the front cutting surface of the head, at least some of the channels being in communication with the openings and along the head. It extends in the axial direction. Optionally, about half of the channels are provided in communication with the openings in the cutting surface.

Preferably, the cutting elements comprise cutting buttons embedded in the head. The cutting buttons may be formed of a carbide material according to a conventional arrangement. As can be seen, the present drill bit may include any head configuration in addition to the distribution of different cutting buttons in the cutting head. Preferably, the cutting buttons comprise gauge buttons, inner buttons and radially inner buttons provided on the cutting surface.

Certain implementations of the invention will now be described with reference to the accompanying drawings and by way of example only.
1 is a perspective view from above of a percussion drill bit according to a specific implementation of the present invention;
Fig. 2 is a side perspective view of the drill bit of Fig. 1;
Fig. 3 is a perspective view from below of the drill bit of Fig. 2;
Fig. 4 is a rear end perspective view of the drill bit of Fig. 3;
5 is a cross-sectional perspective view of the drill bit of FIG. 3;

1 to 3, the percussive drill bit 10 includes a cutting head 11 extending the elongated skirt 12 axially rearward. The head 11 comprises a forward facing cutting surface 13 that is domed in the forward cutting direction according to the particular implementation. The plurality of ultra-hard cutting buttons are embedded in the cutting surface 13 and, as can be seen, comprise radially outer gauge buttons 14a and inner buttons 14b. The head 11 has a raised annular shoulder 16 on which gauge buttons 14a are mounted in the axial front region.

Referring to FIG. 5, the skirt 12 is hollow and comprises an inner bore 26 centered about the longitudinal axis 19 of the bit 10. A set of flushing fluid passages 27 extend axially forward from the front end 28 of the bore 26 so as to appear at the cutting surface 13 as openings 15. According to a particular implementation, three fluid passages are provided in communication with the bore 26 so as to appear at the cutting surface 13. Each groove or channel 18a projects radially outward from each opening 15 in the direction from the axis 19 to the head shoulder 16. The channels 18a are recessed into the cutting surface 13 and also the shoulder 16 so as to extend axially rearward from the head 11 along the entire axial length of the skirt 12. The bit 10 terminates at the first channel 18a in fluid communication with the respective passage 27 (and the opening 15), and at the axial front end of the neck 12d and is in the inner region of the face 13. It comprises two types of flushing grooves comprising a second channel 18b that does not extend across the axis 19.

1 and 3, the skirt 12 is centered about the axis 19 and the neck 12d (representing the axially rearmost region of the shoulder 16) and the axially rearmost end of the skirt 12 It includes an axial length extending between (12e). Depending on its length, the skirt 12 may be considered to be divided into a number of axial sections defined by the maximum outer diameter of the skirt 12 (within each section). The first section 12a immediately axially behind the neck 12d comprises the smallest diameter; The second intermediate section 12b expands radially with respect to the first section 12a, and the axially rearmost third section 12c is radially extended with respect to the first and second sections 12a, 12b. It is enlarged. Each of the annular step regions 29 provides a transition between different diameter sections 12a, 12b, 12c.

Each of the channels 12a, 12b along the length of the skirt 12 between the neck 12d and the rear end 12e is defined by ribs extending in the axial direction generally indicated by the reference number 17 (i.e. Plank). That is, the ribs 17 extend the entire length of the skirt 12 from the head 11 to the skirt rear end 12e. The circumferential thickness of each rib 17 is non-uniform and changes in the direction of the shaft 19 between the neck 12d and the skirt rear end 12e. Moreover, each rib 17 is curved in the longitudinal direction between the neck 12d and the skirt rear end 12e so as to deviate or deflect in the circumferential direction (alternatively referred to as angular or curved). According to a specific implementation, each of the ribs 17 is bent in the rear second and third sections 12b, 12c but is substantially linear in the axial front section 12a just behind the head 11 . Thus, the channels 18a, 18b are also bent to deviate in the circumferential direction within the second and third sections 12b, 12c (alternatively referred to as angular or curved). As such, at least a portion of the axial length of the ribs 17 and channels 18a, 18b (within sections 12b, 12c) are aligned obliquely with respect to the axis 19. According to a specific implementation, the ribs 17 and channels 18a, 18b (in the sections 12b, 12c) are the shaft ( 19) Follow a partial spiral path around it.

2, the angle θ at which each rib 17 is bent or deflected in the longitudinal direction from the axis 19 (so that it is not oblique or parallel to the axis 19) is 1 to 20°, 3 to It may be in the range of 10° or 3 to 8°. This deviation means the general longitudinal path of the ribs 17 in the second and third sections 12b, 12c. As shown in Fig. 2, the combined rear sections 12b, 12c are the skirts, since each section 12a, 12b, 12c generally represents one-third of the length of each skirt 12. 12) represents most of the length of. The ribs 17 (and channels 18a, 18b) oblique to this axis 19 may have an axial length in the range of 20 to 100%, 30 to 90%, 40 to 80% or 50 to 70%. have.

2 to 4, each of the ribs 17 and channels 18a, 18b may be further defined to include a radially innermost trough 22, which trough in the longitudinal direction ( 20) on the first side and on the opposite side by the rear end 25. Thus, the faces 20 and 25 are named with reference to the rotational direction R (Fig. 4). Each rib 17 comprises a land surface 23 representing the radially outermost region of the skirt 12 within each section 12a, 12b, 12c. The land surface 23 is by the leading edge 21 at the junction with the leading end face 20 and by the trailing edge 24 at the junction with the rear end face 25 (circumferentially around the axis 19). It ends on each side.

The angle θ at which each rib 17 and channel 18a, 18b extends obliquely with respect to the axis 19 is for the general longitudinal path of the ribs 17 and channels 18a, 18b or It may be defined with reference to the relative orientation of the trough 22, the leading end face 20, the leading edge 21, the land face 23, the trailing edge 24 and/or the rear end face 25. According to a specific implementation, the trailing edge 24 is such that the circumferential thickness of each rib 17 decreases in the axially rearward direction towards the skirt rear end 12e across the second and third sections 12b, 12c. It is bent at a larger angle compared to the leading edge 21. Thus, the width in the circumferential direction of each channel 18a, 18b increases in the axially rearward direction across the sections 12b, 12c. When the leading and/or trailing edges 21, 24 are curved along the length, the radius of the leading edge 21 is to provide a corresponding non-parallel alignment of the leading edge 20 and the trailing edge 25. It may be larger than the corresponding radius of the trailing edge 24.

Referring to FIG. 4, the leading end surface 20 is at least radially outer perpendicular to the rotational direction R and aligned with the radial spokes 30 so as to be aligned perpendicular to the tangent of the imaginary circle centered with respect to the axis 19. Includes parts. The rear end face 25 is aligned in the transverse direction with respect to the spokes 30 and the front end face 20 so as to incline radially inward from the land face 23.

Each of the nonlinear longitudinal paths of the ribs 17 and channels 18a, 18b in at least the second and third sections 12b, 12c is a flow of cuttings mixed with flushing fluid, typically expressed as sludge. It is advantageous to facilitate axial rearward transport. In other words, the angular or curved longitudinal orientation of the ribs 17 and channels 18a, 18b is axially rearward along the bore as formed and the rear passage of the sludge from the cutting area in the head 11 Facilitates. In addition, the oblique alignment of the ribs 17 and the channels 18a, 18b facilitates the axial rear extraction of the drill bit 10 which is also rotated in the direction R during extraction. Removing cut debris and flushing fluid from the head 11 and from around the outer area of the skirt 12 not only minimizes possible bore collapse during extraction, but also reduces the risk of the drill bit 10 sticking in the bore during extraction. Decrease.

According to further embodiments, the curved or angular longitudinal deviation of the ribs 17 and channels 18a, 18b is the total axial length of the skirt 12 between the neck 12d and the rear end 12e. Can also be extended. The angle at which each rib 17 is aligned with respect to the axis 19 may be the same for all ribs 17 and in all regions of each rib 17, or the angle of deviation is for different ribs 17 And it may be different in different areas of each rib 17. Thus, the width of each channel 18a, 18b may be the same between the neck 12d and the skirt rear end 12e or may vary in the longitudinal direction.

Claims (15)

As a drill bit 10,
A head (11) with cutting elements (14a, 14b) for abrasion of rock by rotation of the drill bit (10) about a longitudinal axis (19);
A skirt 12 extending axially rearward from the head 11;
A plurality of ribs (17) extending axially along the skirt (12) and protruding radially outward to define axially extending channels (18a, 18b), the ribs and channels each being the head The plurality of ribs (17) having a length extending axially in the direction between (11) and the axial rear end (12e) of the skirt (12)
Including,
In the longitudinal direction the ribs 17 and at least a part of the channels 18a, 18b, the longitudinal part of the ribs 17 or the channels 18a, 18b bend obliquely with respect to the longitudinal axis Drill bits, bent or curved. The method of claim 1,
Drill bit, in which some of the ribs (17) and channels (18a, 18b) oblique to the longitudinal axis (19) are located in the axial rear part of the skirt (12). The method of claim 2,
The drill bit, wherein the ribs (17) and the axial front portion of the channels (18a, 18b) are aligned generally parallel to the longitudinal axis (19). The method according to claim 2 or 3,
The axial rear portion is 20%, 30%, 40% of the length of the skirt between the axial rearmost region 12d of the head 11 and the axial rear end 12e of the skirt 12 Drill bits, extending to 50%, 60%, 70%, 80% or 90%. The method according to any one of claims 1 to 4,
The drill bit, wherein the longitudinal portion of the ribs and channels is at least partially helical around the axis (19). The method according to any one of claims 1 to 5,
Each rib includes a front end surface 20 and a rear end surface 25 separated by a land surface 23 facing outward in the radial direction, and the front and rear end surfaces 20 and 25 are the channels 18a , At least partially defining 18b). The method of claim 5,
In the longitudinal direction, both the front and rear end surfaces 20 and 25 of the ribs 17 are bent or bent in the same circumferential direction around the axis 19 so that both the front and rear end surfaces 20 and 25 are aligned obliquely with respect to the axis 19 Being, drill bit. The method of claim 6 or 7,
In the longitudinal direction, at least a portion of the leading edge 21 and the trailing edge 24 of the ribs 17 at the junction between the land surface 23 and each of the leading end faces 20 and the rear end faces 25 The drill bit is bent or bent so that it is aligned obliquely with respect to the axis (19). The method of claim 8,
A drill bit, wherein a portion of the leading edge (21) and the trailing edge (24) oblique to the axis (19) is located in the axial rear portion of the skirt (12). The method according to any one of claims 1 to 9 according to claim 6,
A drill bit, in a cross section perpendicular to the longitudinal axis, the leading section (21) being aligned generally perpendicular to the direction of rotation (R) of the drill bit about the axis (19). The method of claim 10,
In a cross section perpendicular to the axis 19, the rear end section 25 is aligned transversely to the direction of rotation R of the drill bit 10 and/or obliquely to the leading end section 20 , Drill bit. The method according to any one of claims 1 to 11,
The drill bit, wherein the angle θ at which the ribs (17) bend or bend so that the length of the ribs (17) deviates in the circumferential direction is in the range of 1 to 20° relative to the axis (19). The method of claim 12,
The above range is 3 to 10°, 3 to 8° or 4 to 6°. The method according to any one of claims 1 to 13,
The drill bit extends axially from the front end 28 of the inner bore 26 to appear as openings 15 in the inner bore 26 and the front cutting surface 13 of the head 11. A drill bit comprising passages (27), wherein at least some of the channels (18a) extend axially along the head (11) in communication with the openings (15). The method according to any one of claims 1 to 14,
The drill bit, wherein the cutting elements comprise cutting buttons (14a, 14b) embedded into the head (11).

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