CN214170457U

CN214170457U - Bottom expanding drill bit

Info

Publication number: CN214170457U
Application number: CN202022726042.7U
Authority: CN
Inventors: 张�雄; 倪文兵; 贾嵘; 徐永浩; 朱立强; 吕彬
Original assignee: China Railway Siyuan Survey and Design Group Co Ltd; Southwest Survey and Design Co Ltd of China Railway Siyuan Survey and Design Group Co Ltd
Current assignee: China Railway Siyuan Survey and Design Group Co Ltd; Southwest Survey and Design Co Ltd of China Railway Siyuan Survey and Design Group Co Ltd
Priority date: 2020-11-23
Filing date: 2020-11-23
Publication date: 2021-09-10
Anticipated expiration: 2030-11-23

Abstract

The application relates to a bellout drill bit field, this bellout drill bit includes: the drill rod is provided with an axial groove and a sliding groove, the blade is at least partially arranged in the sliding groove and moves along the sliding groove to protrude or retract the drill rod, the pushing piece is arranged below the blade, and the pushing piece is connected with the drill rod in a sliding mode so as to move along the axial groove. The drill rod is characterized in that a first guide piece is arranged on the blade, a second guide piece is arranged on the drill rod, and the blade and the drill rod are matched through the first guide piece and the second guide piece to limit the protruding displacement of the blade out of the drill rod, so that the blade cannot be completely separated from the drill rod, and the blade is prevented from sliding out and falling in a non-working state.

Description

Bottom expanding drill bit

Technical Field

The application relates to reaming tool field, especially relates to a bellout drill bit.

Background

The post-concrete anchoring technique is widely used in many engineering fields due to its advantages of economy, quickness, ease of construction, etc. The post-anchoring technology refers to anchoring on an existing concrete structure through related means, and comprises a mechanical anchor bolt, a chemical bar planting and the like, wherein the mechanical anchor bolt realizes anchoring on a structural fixing piece through mechanical interlocking between a grooving reaming hole at the bottom of a concrete drilling hole and an anchor bolt expansion head, and the grooving reaming hole needs to be completed through a special bottom-enlarging drill bit.

The related bottom expanding drill bit generally adopts a gear and rack transmission mode to realize the expansion and contraction of the blade at the end part of the drill bit, and the structure of the hole expanding drill bit in the mode is complex and the cost is high; the bottom expanding drill bit also adopts the limiting mode of the drill rod and the pushing piece to realize the expansion and the contraction of the blade by using the blade to slide, the bottom expanding drill bit in the form has simple structure, convenient installation and lower cost, but the sliding connection mode of the blade ensures that the blade easily slides away from the drill rod when not in use, the working efficiency is influenced, and the cost of instruments is increased by replacing the blade.

SUMMERY OF THE UTILITY MODEL

In view of this, the present application provides a bottom-expanding drill bit to solve the technical problem of preventing the blade from easily sliding off the drill rod and falling when not in use.

The utility model provides a bellout drill bit that this application embodiment provided includes: the drill rod is provided with an axial groove extending along the axis of the drill rod from the bottom end to the top, and the axial groove penetrates through the drill rod in the radial direction; the drill rod is provided with a sliding groove which obliquely and downwardly extends to the axial groove from the outer side surface of the drill rod; a blade disposed at least partially within the chute and movable along the chute to project or retract into the drill rod; wherein the blade is provided with a first guide and the drill rod is provided with a second guide, the first guide cooperating with the second guide to slidably connect the blade and the drill rod; and the pushing piece is arranged below the blade and is connected with the drill rod in a sliding mode so as to move along the axial groove.

Further, the upper end of the second guide is closed, and the lower end of the second guide extends to the bottom end of the drill rod.

Furthermore, the first guide part is a protrusion protruding out of the blade, the second guide part is a guide groove formed in the wall surface of the sliding groove, and the protrusion is slidably engaged with the guide groove; wherein the guide groove includes: a first subslot inclined downward from the upper end of the second guide toward the direction close to the axis, and a second subslot communicating with the lower end of the second guide of the first subslot; the extending direction of the second subslot and the extending direction of the first subslot form a preset angle.

Further, the extending direction of the second subslot is basically parallel to the axial direction of the drill rod.

Further, the first guide member is a groove formed in the surface of the blade, the second guide member is a guide table protruding on the wall surface of the slide groove, and the groove and the guide table are slidably engaged with each other.

Further, the ejector includes: a connection part connected with the drill rod and capable of moving along the axial groove to protrude or retract into the axial groove; the base is arranged below the connecting part and fixedly connected with the connecting part.

Furthermore, the connecting part is provided with a strip-shaped through hole with two closed ends, and the extending direction of the through hole is basically parallel to the axis of the drill rod; the bottom-expanding drill bit further comprises a connecting piece which penetrates through the through hole and the axial groove and is used for slidably connecting the connecting part and the drill rod.

Furthermore, the base is a cone with a cone top positioned below, and the bottom of the cone is fixed with the connecting part; the base and the drill rod are coaxially arranged.

Further, the blade includes: the cutting edge is positioned on the outer edge of the blade and is far away from one side of the axis of the drill rod; the cutter back is positioned on one side of the blade close to the axis of the drill rod; the upper sliding surface is connected with the upper end of the cutting edge and the upper end of the knife back, and the upper sliding surface is abutted with the sliding groove; the lower sliding surface is connected with the lower end of the cutting edge and the lower end of the knife back, and the lower sliding surface is abutted to the connecting part.

Furthermore, the connecting part is provided with an inclined plane which is abutted against the lower sliding surface of the blade, and the inclined plane is far away from the axis of the drill rod from top to bottom.

The application embodiment provides a bellout drill bit includes: the drill rod is provided with an axial groove and a sliding groove, the blade is at least partially arranged in the sliding groove and moves along the sliding groove to protrude or retract the drill rod, the pushing piece is arranged below the blade, and the pushing piece is connected with the drill rod in a sliding mode so as to move along the axial groove. The drill rod is provided with a first guide piece, a second guide piece and a first guide piece, wherein the first guide piece and the second guide piece are clamped mutually. The blade and the drilling rod are matched through the first guide piece and the second guide piece, so that the blade is limited in the sliding process along the sliding groove and cannot be completely separated from the drilling rod, and the blade is prevented from sliding out and falling in a non-working state.

Drawings

FIG. 1 is a schematic cross-sectional view of a reamer bit according to an embodiment of the present disclosure in one state;

FIG. 2 is a schematic cross-sectional view of a reamer bit according to an embodiment of the present disclosure in another state;

fig. 3 is a schematic structural diagram of a pushing member according to an embodiment of the present disclosure;

FIG. 4 is an exploded view of a reamer bit provided in embodiments of the present application;

FIG. 5 is a cross-sectional view of the drill rod of FIG. 4 provided by an embodiment of the present application;

FIG. 6 is an exploded view of another reamer bit according to embodiments of the present application;

FIG. 7 is a schematic structural diagram of a blade provided in an embodiment of the present application;

FIG. 8 is a schematic structural view of another pushing member provided in the embodiments of the present application;

fig. 9 is a side view of the pusher of fig. 8 according to an embodiment of the present application.

Description of reference numerals:

10-a drill rod; 11-axial grooves; 12-a chute; 13-a second guide; 131-a first subslot; 132-a second subslot; 20-pushing the piece; 21-a connecting part; 211-a through hole; 212-a boss; 22-a base; 30-a blade; 31-a blade edge; 32-knife back; 33-an upper sliding surface; 34-a lower sliding surface; 35-a first guide; 40-connecting piece.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the scope of the invention.

Various combinations of the specific features in the embodiments described in the detailed description may be made without contradiction, for example, different embodiments may be formed by different combinations of the specific features, and in order to avoid unnecessary repetition, various possible combinations of the specific features in the present application will not be described separately.

In the following description, the term "first \ second \ … …" is referred to merely to distinguish different objects and does not indicate that there is identity or relationship between the objects. It should be understood that the references to "above" and "below" are to be interpreted as referring to the orientation during normal use.

It is to be noted that the term "comprises," "comprising," or any other variation thereof is intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element. The term "coupled", where not otherwise specified, includes both direct and indirect connections.

The bottom expanding drill bit is used in the technical field of post-anchoring, and the working principle of the bottom expanding drill bit is briefly explained below, firstly, a straight hole with a fixed aperture is drilled, and the drill bit is taken out; then, the bottom expanding drill bit extends into the bottom of the straight hole which is drilled in advance, and a blade of the bottom expanding drill bit extends out of the bottom expanding drill rod to cut the wall of the straight hole, so that the bottom hole is expanded; when the bottom hole is enlarged, the blade retracts into the drill rod to lift the drill bit. If the blade falls off during the cutting process or during the drill bit extraction, it is difficult to retrieve, requiring blade replacement, increasing the cost of the instrument.

As shown in fig. 1, an embodiment of the present application provides a bottom-expanding drill bit including: the drill rod 10, the pushing piece 20 and the blade 30, wherein the drill rod 10 is provided with an axial groove 11 extending along the axis of the drill rod 10 from the bottom end to the top. Specifically, the drill rod 10 is substantially cylindrical, the axis of the drill rod 10 is the central axis of rotation of the drill rod 10, and the bottom end of the drill rod 10 is the lower boundary of the drill rod 10 in the normal operating state. An axial slot 11 extends upwardly along the axis of the drill rod 10 from the lowermost boundary opening of the drill rod 10. The axial grooves 11 extend in the radial direction of the drill rod 10. Specifically, the radial direction of the drill rod 10 refers to the diameter direction of the drill rod 10, and is perpendicular to the axial direction of the drill rod 10, and the radial direction is the left-right direction as shown in fig. 1; the axial groove 11 is divided into two parts throughout the radial direction of the drill rod 10, i.e., the cross section of the drill rod 10, and the axial groove 11 communicates with the outside in the radial direction of the drill rod 10.

As shown in fig. 1, the drill rod 10 is provided with a slide groove 12 extending obliquely downward from the outer side surface of the drill rod 10 to the axial groove 11. Specifically, the drill rod 10 is substantially cylindrical, the outer side surface of the drill rod is a cylindrical side surface, and the number of the slide grooves 12 is two and is located on two sides of the axis of the drill rod 10. Each slide groove 12 extends from the outer side surface of the drill rod 10 to the axial groove 11, and the slide grooves 12 extend in a direction inclined downward and inward as viewed from an end located on the outer side surface of the drill rod 10 to an end located on the axial groove 11. Specifically, two sliding grooves 12 symmetrically arranged with respect to the axis of the drill rod 10 communicate with each other in the radial direction of the drill rod 10, and the radial direction of the sliding grooves 12 is perpendicular to the radial direction of the axial grooves 11.

Optionally, the sliding grooves 12 are symmetrically arranged along the axis of the drill rod 10, so that the intersection points of the sliding grooves 12 on the two sides are on the axis of the drill rod 10 to form a V-shaped sliding groove, which is beneficial for the blade 30 to uniformly protrude or retract into the drill rod 10 towards the two sides, that is, one end of the sliding groove 12 is located on the axis of the drill rod 10 and is communicated with the axial groove 11, and the other end is located on the outer side surface of the drill rod 10.

As shown in fig. 2, the blade 30 is at least partially disposed within the slide channel 12 and is movable along the slide channel 12 to project or retract the drill rod 10. In particular, protruding means that the blade 30 is away from the axis of the drill rod 10, and the outermost edge of the blade 30 protrudes beyond the edge of the drill rod 10; the outermost edge of the blade 30 refers to the side of the blade 30 furthest from the axis of the drill rod 10. The take-in is that the outermost edge of the blade 30 is closer to the axis of the drill rod 10 than the edge of the drill rod 10 or both are flush. Fig. 1 shows a state in which the blade is received in the drill rod 10, and fig. 2 shows a state in which the blade 30 protrudes from the drill rod 10. At least partially disposed within the channel 12, meaning that the blade 30 must have a portion disposed within the channel 12 for movement along the channel 12; it is also possible that the blade 30 is entirely located within the chute 12 in some circumstances.

As shown in fig. 2, the blade 30 is provided with a first guide 35. Specifically, the sliding chute 12 has two side walls disposed oppositely, and a bottom wall disposed between the two side walls, and the side walls and the bottom wall enclose the sliding chute 12 to form a space for accommodating the blade 30; the first guide 35 is provided on the face of the blade 30 facing the side wall of the chute 12.

Alternatively, the first guide 35 may be provided on one of the faces of the side wall of the blade 30 facing the chute 12, or may be provided on both faces of the side wall of the blade 30 facing the chute 12.

As shown in fig. 2, the drill rod 10 is provided with a second guide 13. Specifically, the second guide 13 is provided on a side wall of the chute 12, or is provided through the side wall of the chute 12; the through-penetration means that the through-penetration is not provided on a wall surface of a side wall of the chute 12, but is provided through the wall surface. The first guide 35 cooperates with the second guide 13 to slidably connect the blade 30 and the drill rod 10. Specifically, the first guide 35 cooperates with the second guide 13 to allow the blade 30 and the drill rod 10 to slide relative to one another within a range in which the blade 30 slides between the displacements defined by the first guide 35 and the second guide 13.

As shown in fig. 2, the ejector 20 is disposed below the blade 30. Specifically, below means below in a normal operating state, such as the below shown in fig. 2. As shown in fig. 1 and 2, the pusher 20 is slidably connected to the drill rod 10 so as to be movable along the axial slot 11. In particular, a portion of the pusher 20 is slidable within the axial slot 11, so that the pusher 20 and the drill rod 10 can slide relative to each other.

In some embodiments, as shown in fig. 1 and 3, the pusher 30 includes: a connecting portion 21 and a base 22. The coupling portion 21 is coupled to the drill rod 10 and is movable along the axial slot 11 to protrude or retract into the axial slot 11. Specifically, the connecting portion 21 is in the shape of a sheet having a certain thickness, which is a distance between two opposite surfaces of the sheet-shaped object having a relatively large area. The thickness of the connecting part 21 is slightly smaller than the width of the axial groove 11, so that the connecting part 21 can extend into the axial groove 11 from bottom to top and move up and down in the axial groove; the width of the axial groove 11 refers to the distance between the opposite walls of the axial groove 11. Protruding means that the connecting portion 21 at least partially protrudes out of the axial groove 11; the retraction means that the connecting portion 21 extends entirely into the axial groove 11.

As shown in fig. 1 and 3, the base 22 is disposed below the connection portion 21 and is fixedly connected to the connection portion 21. Specifically, one end of the connecting portion 21, which is far away from the blade 30, is fixedly connected with the base 22, so that the base 22 and the connecting portion 21 can move synchronously; the fixed connection means that the connecting part 21 and the base can be connected through threads, tenon-and-mortise connection, bonding and the like.

In some embodiments, as shown in fig. 1 and 3, the base 22 is in the form of a cone with its apex below and the base of the cone is fixed to the connecting portion 21. Specifically, the method comprises the following steps. The cone below the base 22 cone, i.e., the inverted cone, with the cone apex facing the bottom of the hole being reamed in the operating condition, facilitates reducing the friction between the stripper 20 and the bottom reamed substrate during rotation of the drill pipe 10. The base 22 is arranged coaxially with the drill rod 10. Specifically, the base 22 has an inverted conical shape, and the rotation center axis thereof can be aligned with the axis of the drill rod 10.

In some embodiments, as shown in fig. 3, the connecting portion 21 is formed with a through hole 211 having two closed ends. Specifically, closed means that the person can not pass through the device by being tightly closed; two ends refer to the two tops or ends of an object; the two ends of the through hole 211 are closed, which means that the two ends of the through hole 211 are adjacent to the solid in the length direction of the through hole 211 rather than directly communicating with the external space.

Alternatively, the through hole 211 may have a substantially rectangular shape or a substantially elliptical shape. As shown in fig. 3, the top of the through hole 211 in the length direction is arc-shaped, so that the contact area between the connecting member and the connecting portion 21 when the connecting member is located at the top of the connecting portion 21 is increased, and the stress on the connecting member and the connecting portion 21 per unit area is reduced, thereby preventing the connecting portion 21 from being damaged and preventing the connecting member from being broken. As shown in fig. 1 and 3, the through-hole 211 extends in a direction substantially parallel to the axis of the drill rod 10. Specifically, the extending direction of the through hole 211 refers to the length direction of the through hole 211, and the length direction is parallel to the axial direction of the drill rod 10, i.e., the direction is the same.

In some embodiments, as shown in FIG. 4, the reamer head further includes a coupling member 40 extending through the through bore 211 and the axial slot 11 to slidably couple the coupling member 21 and the drill rod. Specifically, the connecting member 40 is elongated and penetrates the axial groove 11 in the width direction of the axial groove 11 (the direction perpendicular to the plane of the paper shown in fig. 4) perpendicular to the radial direction of the drill rod 10 through which the axial groove penetrates. The coupling portion 21 extends into the axial slot 11 and the coupling portion 21 and the drill rod 10 are completed by the coupling member 40 extending through the axial slot 11 and through the through hole 211.

Alternatively, the cross section of the connecting member 40 may be circular, square, or other shapes such as diamond.

The utility model provides a expand end drill bit, when carrying out work, stretch into the straight hole that beats in advance with this expand end drill bit, top ejector 20 touches the hole bottom at first, the hole bottom exerts ascending effort to top ejector 20, top ejector 20 moves the top along axial groove 11, top ejector 20 and blade 30 contact, upwards promote blade 30 and make blade 30 upwards outwards move along the spout, thereby outstanding drilling rod 10, the blade 30 of outstanding drilling rod 10 is under the rotary action of turning round, the reaming cutting. When the hole expansion is finished, the drill bit is lifted, the drill rod 10 is acted by an upward acting force, the blade 30 is acted by the upward acting force correspondingly through the connection with the blade 30, the blade 30 moves upwards along the sliding groove 12 and is collected into the drill rod, the blade 30 and the drill rod 10 are matched through the first guide piece 35 and the second guide piece 13, the moving direction of the blade 30 is limited, the connection relation with the drill rod 10 cannot be separated, and the blade 30 is prevented from sliding out and falling in the non-working state lifted by the drill bit.

In some embodiments, as shown in fig. 4, the upper end of the second guide 13 is closed and the lower end of the second guide 13 extends to the bottom end of the drill rod 10. Specifically, the closed state means that the drill rod is not communicated with the external space, the upper end means the upward end of the second guide 13, the upper end of the second guide 13 is closed, and the upper end of the second guide 13 is not communicated with the external space but is in adjacent contact with the drill rod 10 along the extending direction of the second guide 13, that is, the upward displacement of the first guide 35 is limited by the upper end of the second guide 13.

In some embodiments, as shown in fig. 4, the first guide 35 is a projection protruding from the blade 30. Specifically, the protrusion is provided on a surface of the blade 30 facing the side wall of the chute 12, and may be one surface or both surfaces. The bulge can be in a spherical shape, a cylindrical shape or a calabash shape. The second guide 13 is a guide groove formed in a wall surface of the slide groove 12. Specifically, the guide groove is provided on a wall surface of a side wall of the chute 12, and may be provided on only one of the surfaces or both surfaces. The number of the guide grooves is at least two, and the two guide grooves are symmetrically arranged along the axis of the drill rod 10. The protrusion is slidably engaged with the guide groove. Specifically, the engagement means that the first guide 35 in a convex shape and the second guide 13 in a guide groove form a snap-fit relationship, so that the first guide 35 does not disengage from the second guide 13, and the blade 30 does not disengage from the connection with the drill rod 10.

In some embodiments, as shown in fig. 5, the guide groove includes: a first sub-groove 131 in which the upper end of the second guide 13 is inclined downward toward the axial direction, and a second sub-groove 132 in which the lower end of the second guide 13 communicates with the first sub-groove 131. Specifically, the first sub-groove 131 is inclined in a direction parallel to the inclination direction of the same slide groove 12. The guide groove is composed of a first sub-groove 131 and a second sub-groove 132, the first sub-groove 131 is communicated with the second sub-groove 132, the first sub-groove 131 is located above the second sub-groove 132, and the width of the first sub-groove 131 is substantially the same as that of the second sub-groove 132, so that the first guide 35 can move back and forth in the first sub-groove 131 and the second sub-groove 132. The extending direction of the second sub-groove 132 and the extending direction of the first sub-groove 131 form a predetermined angle. Specifically, the extending directions of the first subslot 131 and the second subslot 132 do not overlap, that is, the extending directions of the two may intersect. The preset angle refers to a predetermined angle, and the angle may be an obtuse angle, such as 120 °, 135 °, 150 °, and the like.

In some embodiments, as shown in fig. 4 and 5, the second subslot 132 extends in a direction substantially parallel to the axial direction of the drill rod 10. Specifically, the second sub-groove 132 may extend in substantially the same direction as the axial direction of the drill rod 10. Basically, the absolute parallelism and identity are not required in consideration of processing and assembly errors. The blade 30 is assembled to the drill rod 10 from the bottom end of the drill rod 10, with the second sub-slot 132 oriented in a vertical direction as shown in fig. 5 to facilitate machining and assembly of the blade 30 to the drill rod 10.

In some embodiments, as shown in fig. 6, the first guide 35 is a groove cut into the surface of the blade 30. Specifically, the groove is provided on a surface of the blade 30 facing the wall surface of the chute 12, and may be provided on one surface or both surfaces. The groove is closed at both ends and is inclined upwardly and outwardly along the length of the blade 30 at the same angle as the associated slot 12. The second guide 13 is a guide stand protruding on the wall surface of the chute 12. Specifically, the guide table may be spherical, cylindrical, or gourd-shaped, and the protrusion of the guide table from the wall surface of the sliding chute 12 means that the guide table and the wall surface of the sliding chute 12 are not on the same plane, and the guide table does not extend to the bottom end of the drill rod 10. The groove is slidably engaged with the guide table. Specifically, the recess cooperatees with the direction platform, and the direction platform can slide from top to bottom in the recess, and the block indicates to form the joint relation between direction platform and the recess for the direction platform can not break away from the recess. The radial width of the guide table and the groove wall on the same plane of the groove is not more than the width of the guide groove, and the friction force between the guide table and the groove is favorably reduced.

Optionally, a through-hole is provided in the drill rod 10, through which the guide table passes and protrudes from the wall of the slide groove 12. The portion of the guide table protruding from the wall of the chute 12 is adapted to engage with the recess in the blade 30 to allow the blade 30 to move within the confines of the recess. In some embodiments, as shown in fig. 6 and 7, the blade 30 includes: and the cutting edge 31 is positioned on the outer edge of the blade 30 and is far away from the axis of the drill rod. Specifically, the outer edge refers to the outer edge of the blade 30 on the side away from the axis of the outer edge drill rod 10 for reaming and cutting. And a back 32 located on the side of the blade 30 adjacent to the axis of the drill rod 10. Specifically, the back 32 is disposed on a side of the blade 30 near the axis of the drill rod 10, and is used for abutting and limiting the back 32 when the blade 30 is received in the drill rod 10. The upper sliding surface 33 connects the upper end of the blade 31 and the upper end of the blade back 32, and the upper sliding surface 33 abuts against the wall surface of the chute 12. Specifically, the upper end refers to the end point of the blade 31 and the back 32 which is upward along the axis of the drill rod 10, the upper sliding surface 33 formed by the upper end connecting line of the blade 31 and the back 32 is abutted against the wall surface of the sliding chute 12, and the abutting means that the two abutted parts are in contact with each other and abutted to form close contact. The upper sliding surface 33 moves diagonally up and down along the chute 12. The lower sliding surface 34 connects the lower end of the blade 31 and the lower end of the blade back 32, and the lower sliding surface 34 abuts against the connecting portion 21. Specifically, the lower end refers to the end point of the blade 31 and the back 32 which is downward along the axis of the drill rod 10, the lower end connecting line of the blade 31 and the back 32 forms a lower sliding surface 34, the lower sliding surface 34 abuts against the upper end surface of the connecting portion 21, and the upper end surface of the connecting portion 21 refers to the surface of the connecting portion 21 which is upward along the axis of the drill rod 10. Upward and downward are the up-down directions as shown in fig. 1. The lower sliding surface 34 moves away from and towards the axis of the drill rod 10 on the upper end face of the connecting portion 21.

It should be noted that the connecting portion 21 pushes the lower sliding surface 34 of the blade 30 to move the blade 30 upward along the axis of the drill rod 10, and when the upper sliding surface 33 abuts against the sliding slot 12, the blade 30 is pushed upward along the axis of the drill rod 10 by the connecting portion 21, so that the upper sliding surface 33 moves away from the axis of the drill rod 10 along the sliding slot 12, and the blade 30 can protrude or retract into the drill rod 10.

Alternatively, the number of the blades 30 is two, and the blades 30 are symmetrically arranged with respect to the axis of the drill rod 10. When the two blades 30 are put into the drill rod 10, the knife backs 32 of the two blades 30 are abutted, so that the transverse displacement of the blades 30 is limited, and the limiting is better carried out.

In some embodiments, as shown in FIG. 8, the coupling 21 is provided with a ramp surface that abuts the lower sliding surface 34 of the blade 30, the ramp surface being spaced from top to bottom away from the axis of the drill rod 10. Specifically, the blade 30 is disposed above the connecting portion 21, and the lower sliding surface 34 of the blade 30 abuts against the upper end surface of the connecting portion 21. The upper end surface is an inclined surface matched with the upper sliding surface 33, which is beneficial to the tight contact between the connecting part 21 and the blade 30 and is convenient for the stress of the blade 30.

Alternatively, as shown in fig. 4 and 9, the connecting portion 21 may be formed with elongated bosses 212, and the bosses 212 are symmetrically disposed along the axis. The width of each boss 212 is slightly smaller than that of the guide groove, so that the bosses 212 can slide up and down in the second sub-grooves 132 of the guide grooves, and accumulation of sand in the guide grooves is avoided.

The above description is only for the preferred embodiment of the present application and is not intended to limit the scope of the present application, and all modifications and equivalents of the subject matter of the present application, which are made by the following claims and their equivalents, or which are directly or indirectly applicable to other related arts, are intended to be included within the scope of the present application.

Claims

1. A bellout drill bit, comprising:

the drill rod is provided with an axial groove extending along the axis of the drill rod from the bottom end to the top, and the axial groove penetrates through the drill rod in the radial direction; the drill rod is provided with a sliding groove which obliquely and downwardly extends to the axial groove from the outer side surface of the drill rod;

a blade disposed at least partially within the chute and movable along the chute to project or retract into the drill rod; wherein the blade is provided with a first guide and the drill rod is provided with a second guide, the first guide cooperating with the second guide to slidably connect the blade and the drill rod;

and the pushing piece is arranged below the blade and is connected with the drill rod in a sliding mode so as to move along the axial groove.

2. The bottom-reaming bit according to claim 1, wherein the upper end of the second guide is closed and the lower end of the second guide extends to the bottom end of the drill rod.

3. The under-reaming bit according to claim 2, wherein the first guide is a protrusion protruding from the blade, the second guide is a guide groove formed in a wall surface of the slide groove, and the protrusion is slidably engaged with the guide groove;

wherein the guide groove includes: a first subslot inclined downward from the upper end of the second guide toward the direction close to the axis, and a second subslot communicating with the lower end of the second guide of the first subslot; the extending direction of the second subslot and the extending direction of the first subslot form a preset angle.

4. The bottom-reaming bit according to claim 3, wherein the second subslot extends in a direction substantially parallel to the axial direction of the drill rod.

5. The under-reamer of claim 1, wherein said first guide is a groove formed in a surface of said blade, and said second guide is a guide table protruding from a wall surface of said slide groove, said groove being slidably engaged with said guide table.

6. The under-reamer of claim 1 or 2, wherein the ejector comprises:

a connection part connected with the drill rod and capable of moving along the axial groove to protrude or retract into the axial groove;

the base is arranged below the connecting part and fixedly connected with the connecting part.

7. The bottom-expanding drill bit as claimed in claim 6, wherein the connecting part is provided with an elongated through hole with two closed ends, and the extending direction of the through hole is substantially parallel to the axis of the drill rod; the bottom-expanding drill bit further comprises a connecting piece which penetrates through the through hole and the axial groove and is used for slidably connecting the connecting part and the drill rod.

8. The bottom-expanding drill bit as claimed in claim 6, wherein the base is a cone with a cone top below, and the bottom of the cone is fixed with the connecting part; the base and the drill rod are coaxially arranged.

9. The under-reamer of claim 6, wherein the blades comprise:

the cutting edge is positioned on the outer edge of the blade and is far away from one side of the axis of the drill rod;

the cutter back is positioned on one side of the blade close to the axis of the drill rod;

the upper sliding surface is connected with the upper end of the cutting edge and the upper end of the knife back, and the upper sliding surface is abutted with the sliding groove;

the lower sliding surface is connected with the lower end of the cutting edge and the lower end of the knife back, and the lower sliding surface is abutted to the connecting part.

10. The underreamer of claim 9, wherein the coupling portion is provided with a ramp surface that abuts the lower blade sliding surface, the ramp surface being spaced from the axis of the drill rod from top to bottom.