CN214365889U - Bottom expanding drill bit - Google Patents

Abstract

The application relates to a bellout drill bit field, this bellout drill bit includes: the bottom end of the drill rod is upwards provided with an axial groove extending along the axis of the drill rod, and the axial groove penetrates through the diameter direction of the drill rod; the drill rod is also provided with a sliding groove which obliquely extends downwards from the outer side surface of the drill rod to the axial groove; the pushing piece comprises a connecting part and a base fixed with the connecting part, and the connecting part can move along the axis of the drill rod in the axial groove; the blade is arranged on the drill rod and is positioned above the pushing piece; the blade is at least partially arranged in the sliding groove and can move along the sliding groove so as to protrude out of or retract into the drill rod; wherein the part of the blade away from the drill rod axis can be closely matched with the side wall of the chute, and the part of the blade close to the drill rod axis can be loosely matched with the side wall of the chute. The tight fit between the chute and the blade prevents the drill rod from sliding off when not in use.

Description

Bottom expanding drill bit

Technical Field

The application relates to the technical field of drilling equipment, in particular to a bottom expanding 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 anchor bolt, chemistry, embedded bars 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 rod 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-enlarging drill bit to solve the technical problem that a blade is easy to slip off a drill rod and fall off 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 diameter direction of the drill rod; the drill rod is also provided with a sliding groove which obliquely and downwardly extends from the outer side surface of the drill rod to the axial groove; the pushing piece comprises a connecting part and a base fixed with the connecting part, and the connecting part can move along the axis of the drill rod in the axial groove; the blade is arranged on the drill rod and is positioned above the pushing piece; the blade is at least partially arranged in the sliding groove and can move along the sliding groove so as to protrude out of or retract into the drill rod; wherein the part of the blade remote from the drill rod axis can be in tight fit with the side wall of the chute and the part of the blade close to the drill rod axis can be in loose fit with the side wall of the chute.

Further, the width of the chute is substantially constant, and the thickness of the portion of the blade distal from the drill rod axis is greater than the thickness of the portion of the blade proximal to the drill rod axis.

Further, the thickness of the portion of the blade distal from the drill axis and the thickness of the portion of the blade proximal to the drill axis are substantially the same along the length of the blade.

Further, there is a joint between the portion of the blade away from the drill rod axis and the portion of the blade near the drill rod axis, the length of the joint being much less than the length of the blade.

Further, the width of the portion of the chute proximate the drill rod axis is greater than the width of the portion of the chute distal the drill rod axis, and the thickness of the blade is substantially constant.

Further, the tight fit is a transition fit or an interference fit, and the loose fit is a clearance fit.

Further, the blade includes: a cutting edge located at the outer edge of the blade, on the side away from the drill rod axis; a back of a knife on a side of the blade proximate the drill rod axis; 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 wall surface of 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.

Further, the number of the blades is two, and the blades are symmetrically arranged relative to the axis of the drill rod.

Further, the drill rod further comprises a rod cap arranged at the bottom end of the axial groove, and the diameter of the rod cap is the maximum diameter of the cross section of the drill rod; the rod cap is movably connected with the connecting part of the pushing piece relatively.

Further, the rod cap is provided with a pin shaft hole penetrating along the radial direction, the connecting portion is provided with a connecting hole extending along the axis, and a connecting piece penetrates through the pin shaft hole and the connecting hole to connect the rod cap and the pushing piece in a relatively movable mode.

The utility model provides a expand end drill bit, including drilling rod, top pushing part and blade, the blade is installed in the bull stick and is located the top of top pushing part, and the drilling rod upwards offers from the bottom edge the axial groove that the drilling rod axis extends, the drilling rod has still offered the follow the outside side slope downwardly extending of drilling rod reaches the spout of axial groove, the blade at least part sets up in the spout and can follow the spout motion, wherein the blade is kept away from the part of drilling rod axis can with the lateral wall tight fit of spout, the part that the blade is close to the drilling rod axis can with the lateral wall loose fit of spout. Different cooperation modes between the lateral wall through different parts of blade and spout for the blade outwards can push out the blade smoothly through external force when the reaming operation, finishes at the reaming and upwards pulls up the in-process of drill bit, and the concrete pore wall extrudees the blade outside naturally, makes the blade get into the spout, and blade outside part is the close fit relation with the spout, thereby makes the blade be difficult for droing behind sliding into the drilling rod. The utility model provides a bellout drill bit has realized the blade under non-operating condition closely cooperating with the drilling rod through the different thickness that sets up the blade, prevents or has reduced the roll-off of blade under non-operating condition and drop.

Drawings

FIG. 1 is a front view of a reamer bit provided in an embodiment of the present application in one configuration;

FIG. 2 is a side view of a drill stem of a reamer bit provided by an embodiment of the present application;

FIG. 3 is a front view of a pusher provided in accordance with an embodiment of the present application;

FIG. 4 is a side view of a pusher provided in accordance with an embodiment of the present application;

FIG. 5 is a front view of an extension bit provided in accordance with an embodiment of the present application in another state;

FIG. 6 is a cross-sectional view A-A of FIG. 1 as provided by an embodiment of the present application;

FIG. 7 is another cross-sectional view A-A of FIG. 1 as provided by an embodiment of the present application;

fig. 8 is a schematic structural diagram of a blade according to an embodiment of the present application.

Description of reference numerals:

10-a drill rod; 11-axial grooves; 12-a chute; 13-a rod cap; 14-the drill rod axis; 131-pin hole; 20-pushing the piece; 21-a connecting part; 211-connection holes; 22-a base; 30-a blade; 31-a blade edge; 32-knife back; 33-an upper sliding surface; 34-a lower sliding surface; 35-an engagement portion.

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 present application and are not intended to limit the present application.

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 directions referred to describe "up" and "down" are all directions in a normal use state.

It should be noted that the terms "comprises," "comprising," or any other variation thereof, are 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 drill bit extraction, it is inconvenient to retrieve, requiring blade replacement which increases the cost of the instrument.

As shown in fig. 1, an embodiment of the present application provides a bottom-expanding drill bit including: drill rod 10, ejector 20, blade 30.

The front view shown in fig. 1 does not fully describe the internal structure of the drill rod 10, and the side view shown in fig. 2 shows the drill rod 10 from the bottom end up with an axial slot 11 extending along the drill rod axis 14. In particular, the drill rod 10 is substantially cylindrical, the drill rod axis 14 being the central axis of rotation of the drill rod 10 and the bottom end of the drill rod being the lower boundary of the drill rod in normal operation, the axial slot 11 then extending upwardly along the drill rod axis 14 from the lowermost boundary of the drill rod 10. The axial slot 11 extends through the diameter of the drill rod 10. Specifically, the diameter of the drill rod 10 is oriented perpendicular to the drill rod axis 14, as viewed in the left-right direction 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 further provided with a slide groove 12 extending obliquely downward from the outer side surface of the drill rod 10 to the axial groove 11. The drill rod 10 is substantially cylindrical, with the outer side being the cylindrical side, and the number of slide grooves 12 is arranged in two on either side of the drill rod axis 14. 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. In particular, two slide grooves 12, which are symmetrically arranged with respect to the drill rod axis 14, communicate in a radial direction through the drill rod 10, and the radial direction through which the slide grooves 12 extend is perpendicular to the radial direction through which the axial grooves 11 extend.

Alternatively, the slots 12 may be symmetrically disposed along the drill rod axis 14 such that the intersection of the slots 12 on either side is on the axis of the drill rod 10, forming a V-shaped slot to facilitate uniform extension and retraction of the blade 30 into and out of the drill rod 10 on either side. That is, one end of the slide groove 12 is located on the drill rod axis and communicates with the axial groove 11, and the other end is located on the outer side of the drill rod 10.

As shown in fig. 3, the pushing member 20 includes a connecting portion 21 and a base 22 fixed to the connecting portion 21. In particular, the coupling portion 21 is substantially flat and has a length slightly less than the length of the axial slot 11 and a width less than the width of the axial slot 11 to facilitate the positioning of the coupling portion 21 in the axial slot 11 and movement along the drill axis. Connecting portion 21 and base 22 fixed connection for connecting portion 21 and base 22 can move simultaneously, and is concrete, and base 22 is located connecting portion 21's below, and base 22 can be hinged connection with connecting portion 21's fixed connection, also can be bolted connection, can also be mortise and tenon joint, as long as it is fixed with base 22 to realize connecting portion 21, and this application does not do further injectly here.

As shown in fig. 4, the base 22 is generally conical with the top of the cone facing downward for abutting the bottom of the borehole, which facilitates reducing friction between the pusher 20 and the bottom reamed substrate during rotation of the drill pipe 10. The coupling portion 21 moves up and down along the drill rod axis in the axial slot 11, thereby pushing the blade 30 in motion.

In some embodiments, as shown in fig. 1 and 2, the drill rod 10 further comprises a rod cap 13 disposed at the bottom end of the axial slot 11. Specifically, the bottom end refers to the lowest part of the drill rod 10 that is downward along the axis, and the rod cap 13 is provided on the outer side wall of the drill rod 10 at the bottom end of the axial groove 11. The diameter of the rod cap 13 is the largest diameter in the cross-section of the drill rod 10. In particular, the rod cap 13 is substantially cylindrical in shape, with a diameter that is the largest of the various components that the drill rod comprises, preventing ash from falling to the bottom of the reamed hole, and also facilitating the centering of the drill rod 10 in the center of the reamed hole. The rod cap 13 is connected to the connecting portion 21 of the pusher 20 so as to be movable relative thereto. Specifically, the connecting portion 21 moves up and down along the axial direction of the drill rod 10 in the axial groove 11, and in order to prevent the ejector 20 from being detached from the drill rod 10, the connecting portion 21 is movably connected with the rod cap 13, so that the connecting portion 21 is not limited to move up and down along the axis of the drill rod 10, and the displacement of the connecting portion 21 in the up and down movement is also limited.

Alternatively, the connection capable of moving relatively may be a hinge connection or a shaft pin connection, and the connection mode is not limited further in this application as long as the connection mode can limit within a certain range.

In some embodiments, as shown in FIG. 3, the wand cap 13 is provided with a radially-extending pin shaft aperture 131. Specifically, the rod cap 13 is a substantially cylindrical body, and the radial penetration thereof means penetration in the diameter direction. The connecting portion 21 is provided with a connecting hole 211 extending along the axis. Specifically, the connecting portion 21 is flat and extends along the axis of the drill rod 10, and a connecting hole 211 extending along the axial direction is formed on one surface of the connecting portion 21, which is in contact with the axial groove 11. The connecting piece passes through the connecting rod cap 13 and the pushing piece 20 which can move relatively with the connecting hole 211 through the pin shaft hole 131. Specifically, the connecting member extends through the pin shaft hole 131 and the connecting hole 211 to movably fix the lever cap 13 and the connecting portion 21 relative to each other, and the connecting portion 21 moves between displacements defined by the connecting hole 211.

Optionally, the top of the connecting hole 211 in the direction of the drill rod axis 14 is arc-shaped, which is beneficial to increase the contact area between the connecting part 21 and the uppermost part of the connecting part 21, and reduce the stress on the connecting part and the connecting part 21 in unit area, thereby avoiding the damage of the connecting part 21 and the fracture of the connecting part.

Optionally, the width dimension of the connecting hole 211 is slightly larger than the diameter of the pin shaft hole 131, for example, about 1mm larger, which is beneficial to avoid the connecting member moving in the connecting hole 211 from being interfered by friction with the connecting portion 21.

As shown in fig. 1 and 5, the blade 30 is mounted on the drill rod 10 above the pusher 20. Specifically, the ejector 20 is close to the lower end of the drill rod 10 and can move up and down along the axial slot 11, and the blade 30 is positioned above the ejector 20. The blade 30 is disposed at least partially within and movable along the slide channel 12 to project or retract the drill rod 10. Specifically, protruding means that the blade 30 is distal from the spindle axis 14 and the outermost edge of the blade 30 extends beyond the edge of the spindle 10. The outermost edge of the blade 30 refers to the side of the blade 30 furthest from the drill axis 14. The take-in is that the outermost edge of the blade 30 is closer to the turret axis 14 than the edge of the drill rod 10 or both are flush. Fig. 1 shows a state in which the blade 30 is received in the drill rod 10, and fig. 5 shows a state in which the blade 30 protrudes from the drill rod 10. The pushing member 20 pushes the blade 30 upward, so that the blade 30 is forced upward against the wall surface of the chute 12. As the chute 12 is tilted downwardly and inwardly, the blade 30 will move upwardly and outwardly along the tilted chute 12. During the movement of the blade 30, in addition to the displacement in the axial direction of the drill rod 10, there is also a displacement in the radial direction of the drill rod 10, so that the blade 30 can protrude or retract into the drill rod 10.

As shown in fig. 6, the portion of the blade 30 remote from the drill rod axis 14 can be a tight fit with the side walls of the slide channel 12 and the portion of the blade 30 near the axis of the drill rod 10 can be a loose fit with the side walls of the slide channel 12. Specifically, the engagement between the blade 30 and the side wall of the sliding groove is divided into two parts, one part is loosely engaged, i.e., the two parts can slide relative to each other, and the other part is tightly engaged, i.e., the two parts cannot slide relative to each other. The loose fit mode reduces the friction between the blade 30 and the chute 12 after pushing out the rotating rod 10 in the working state, and does not affect the cutting of the blade 30. In the non-working state, when the blade 30 is received in the drill rod 10, the friction force between the blade 30 and the side wall of the sliding groove 12 is increased through the close fit matching mode between the blade 30 and the side wall of the sliding groove 12, so that the blade is not easy to slide out of the drill rod 10.

When the reaming bit provided by the embodiment of the application works, the reaming bit extends into a straight hole which is drilled in advance, the pushing piece 20 pushes the blade 30 upwards to push the blade 30 against the sliding groove 12 when touching the bottom of the hole, so that the blade 30 moves upwards and outwards along the sliding groove to protrude the drill rod 10, and the blade 30 protruding the drill rod 10 performs reaming and cutting under the rotating action of the rotating head. After reaming, the drill bit is lifted and the blades are retracted into the drill pipe 10 under the action of the hole wall.

The bellout drill bit of this application embodiment has realized the blade under non-operating condition and the tight fit of drilling rod through the different thickness that sets up the blade, prevents or has reduced the roll-off of blade under non-operating condition and drop.

In some embodiments, as shown in fig. 6, the width of the slot 12 is substantially constant and the thickness of the portion of the blade 30 distal from the drill axis 14 is greater than the thickness of the portion of the blade 30 proximal to the drill axis 14. Specifically, to achieve a loose fit and a tight fit of the blade 30 with one portion of the side wall of the chute 12, the width of the chute 12 may be unchanged, and the thickness of the blade 30 may be changed. The sliding chute 12 has two side walls disposed opposite to each other and a bottom wall disposed between the two side walls, the side walls and the bottom wall enclose a space for accommodating the blade in the sliding chute 12, the width of the sliding chute 12 is a distance between the two side walls of the sliding chute 12, and fig. 6 shows a dimension of the sliding chute 12 in the up-down direction. The thickness of the blade 30 refers to the dimension of the portion of the blade 30 in the chute 12 in the direction perpendicular to the wall surfaces of the two side walls, and fig. 6 shows the dimension of the blade 30 in the up-down direction. By dividing the blade 30 into two parts, one part away from the drill rod axis 14 (hereinafter referred to as the "away part") and one part close to the drill rod axis 14 (hereinafter referred to as the "close part"), the away part can be in tight fit with the side wall of the slide channel 12 and the close part can be in loose fit with the side wall of the slide channel 12, so that the blade can slide out smoothly during the bottom expanding process and retract into the drill rod without falling off during the lifting process. In particular, how the distant and close portions are arranged can be set according to the actual need, for example, a portion of the blade that is less than a first preset value from the drill axis 14 is the close portion and a portion of the blade that is greater than a second preset value from the drill axis 14 is the distant portion. The thickness of the blade may or may not vary near the interior of the portion and/or far from the portion.

In some embodiments, as shown in fig. 6, the portion of the blade 30 distal from the drill axis 14 is substantially the same thickness and the portion of the blade 30 proximal to the drill axis 14 is substantially the same thickness along the length of the blade 30. It should be noted that the length direction of the blade 30 coincides with the radial direction of the drill rod, and the left and right directions of the blade 30 are shown in fig. 6. The thickness of the blade 30 inside the proximal portion remains substantially constant, and may be, for example, a first thickness value; the thickness away from the inner portion is also maintained constant, for example, at a second thickness value; the first thickness value is less than the second thickness value. Substantially the same means that the thickness of the blade 30 can be considered the same within a certain margin of error. That is, the blade 30 is not a member having a continuously variable thickness, but the thickness variation occurs only between the distant portion and the close portion, and the portion having the thickness variation may have a long or short length, that is, the thickness variation may be relatively severe or relatively gentle.

In some embodiments, as shown in fig. 6, there is a joint 35 between the portion of the blade 30 distal from the drill rod axis 14 and the portion of the blade 30 proximal to the drill rod axis 14. The length of the engagement portion 35 is much smaller than the length of the blade 30. By far less is meant 1/5 that is one dimension smaller than another. Namely: the thickness variation of the blade 30 is achieved by means of a very small length of the abutment 35, the thickness variation of the blade 30 approximating a step change. The engagement portion 35 is much shorter than the length of the blade 30, facilitating a sufficient portion of the blade 30 to fit tightly and loosely against the side walls of the chute 12. Alternatively, the engaging portion 35 may be a gently-transitional slope or a curved surface, which is not limited herein.

In other embodiments, as shown in fig. 7, the width of the portion of the chute 12 proximate the drill rod axis 14 is greater than the width of the portion of the chute 12 distal the drill rod axis 14, and the thickness of the blade 30 is substantially constant. Specifically, by providing a substantially constant thickness of the blade 30, the width of the chute 12 may need to be varied as needed to accomplish the loose and tight fit of the chute 12 to the blade 30. The part of the slide groove 12 close to the drill axis 14 is intended to be loosely fitted with the blade 30 and the part of the slide groove 12 remote from the drill axis 14 is intended to be tightly fitted with the blade 30, so that the width of the part of the slide groove 12 close to the drill axis 14 is set to be larger than the width of the part remote from the drill axis 14.

In some embodiments, the tight fit is a transition fit or an interference fit, as shown in fig. 6 and 7. The tight fit is a fit state in which the fit between the blade 30 and the chute 12 is not easily loosened without an excessive external force, and therefore, it is only necessary to perform interference fit and transition fit with a sufficient frictional force on a full fit surface. The loose fit is a clearance fit. The loose fit is a condition that allows the engagement between the blade 30 and the slot 12 to slide relative to each other substantially without resistance, and thus the clearance fit may be used to reduce the frictional force between the engagement surfaces between the blade 30 and the slot 12.

In some embodiments, as shown in fig. 8, the blade 30 includes: the cutting edge 31 is located on the outer edge of the blade 30, on the side remote from the drill axis 14. In particular, outer edge refers to the outer edge of the side of the blade 30 away from the outer edge drill axis 14 for reaming cutting. A back 32 on the side of the blade 30 adjacent the drill axis 14. Specifically, the back 32 is disposed on a side of the blade 30 adjacent the drill rod axis 14 for limiting abutment with 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 upward along the drill axis 14, the upper sliding surface 33 formed by the connecting line of the upper ends of the blade 31 and the back 32 is abutted against the wall surface of the sliding groove 12, and the abutment refers to the contact and abutment between the two abutting parts, so as 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 drill rod axis 14, the lower end connecting line of the blade 31 and the back 32 forms a lower sliding surface 34, the lower sliding surface 34 is abutted with the upper end surface of the connecting part 21, and the upper end surface of the connecting part 21 refers to the surface of the connecting part 21 which is upward along the drill rod 10 axis. Upward and downward are the up-down directions as shown in fig. 8. The lower sliding surface 34 moves away from and towards the drill rod axis 14 on the upper end face of the connection 21.

It should be noted that the connecting portion 21 pushes against the lower sliding surface 34 of the blade 30 to move the blade 30 upward along the drill rod axis 14 as a whole, and when the upper sliding surface 33 abuts against the sliding slot 12, the blade 30 is pushed upward along the drill rod axis 14 by the connecting portion 21, so that the upper sliding surface 33 moves away from the drill rod axis 14 along the sliding slot 12, and the blade 30 can protrude or retract into the drill rod 10.

In some embodiments, the number of blades 30 is two, with the blades 30 being symmetrically disposed about the drill rod axis. Specifically, the blades 30 are arranged into two symmetrical pieces along the drill rod axis 14, and when the two blades 30 are received in 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 performed.

Alternatively, the number of the blades 30 may be a plurality of pairs symmetrically arranged, as long as the tight fit of the sliding groove 12 of each blade 30 can be achieved, and here, limiting the number of the blades 30 to two is a preferable solution of the embodiment, and is not considered to limit the present application.

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 (10)

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 diameter direction of the drill rod; the drill rod is also provided with a sliding groove which obliquely and downwardly extends from the outer side surface of the drill rod to the axial groove;

the pushing piece comprises a connecting part and a base fixed with the connecting part, and the connecting part can move along the axis of the drill rod in the axial groove;

the blade is arranged on the drill rod and is positioned above the pushing piece; the blade is at least partially arranged in the sliding groove and can move along the sliding groove so as to protrude out of or retract into the drill rod; wherein the part of the blade remote from the drill rod axis can be in tight fit with the side wall of the chute and the part of the blade close to the drill rod axis can be in loose fit with the side wall of the chute.

2. The reamer head of claim 1, wherein the width of the slot is substantially constant and the thickness of the portion of the blade distal from the drill rod axis is greater than the thickness of the portion of the blade proximal to the drill rod axis.

3. The reamer bit of claim 2, wherein the portion of the blade distal from the drill rod axis is substantially the same thickness and the portion of the blade proximal to the drill rod axis is substantially the same thickness along the length of the blade.

4. The under-reaming bit according to claim 3, wherein the portion of the blade remote from the drill rod axis and the portion of the blade proximate to the drill rod axis have a splice therebetween, the length of the splice being substantially less than the length of the blade.

5. The countersink bit according to claim 1, wherein said slot has a width which is greater in a portion of said slot adjacent said drill rod axis than in a portion of said slot remote from said drill rod axis, and said blade has a substantially constant thickness.

6. The under-reamer of any one of claims 1 to 5, wherein the close fit is a transition fit or an interference fit and the loose fit is a clearance fit.

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

a cutting edge located at the outer edge of the blade, on the side away from the drill rod axis;

a back of a knife on a side of the blade proximate the drill rod axis;

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 wall surface of 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.

8. The underreamer bit of claim 5, wherein the number of blades is two, the blades being symmetrically disposed about the drill rod axis.

9. The bottom-reaming bit according to claim 6, wherein the drill rod further comprises a rod cap disposed at the bottom end of the axial slot, the rod cap having a diameter that is the largest diameter in the cross-section of the drill rod; the rod cap is movably connected with the connecting part of the pushing piece relatively.

10. The under-reaming bit according to claim 9, wherein the rod cap is provided with a pin shaft hole extending therethrough in a radial direction, the connecting portion is provided with a connecting hole extending along the axis, and a connecting member passes through the pin shaft hole and the connecting hole to connect the rod cap and the ejector movably relative to each other.

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