Pilot stepped hob drill bit

Abstract

The utility model discloses a pilot step type hob drill bit which comprises a cutterhead and a flange plate used for being connected with a drill rod, the cutterhead comprises a side wall and a bottom ring face, the bottom ring face is welded to the lower end of the side wall, and a first hob is rotatably installed on the bottom ring face. The center of the bottom ring face is welded to the bottom end of a guide sleeve, the guide sleeve is in sliding fit with an inner barrel drill in the vertical direction, and a second hob is rotatably installed on the bottom face of the inner barrel drill. The outer wall of the inner barrel drill protrudes outwards to form at least two lugs, and the outer diameter of the lugs is equal to the inner diameter of the guide sleeve; a top cover for limiting the upper limit position of the inner cylinder drill is welded at the upper end of the guide sleeve; a clamping ring for supporting the lug to limit the lower limit position of the inner cylinder drill is arranged at the lower end of the inner wall of the guide sleeve; the inner cylinder drill is connected with the flange plate through a core pipe, and the core pipe penetrates through a center hole of the top cover; and the upper ring surface of the clamping ring and the inner wall of the guide sleeve are jointly welded with a sector ring clamping strip which is used for abutting against the end part of the lug so as to transmit torque to the cutter head from the inner barrel drill. The drill bit is better in righting effect, and inclined downward drilling can be avoided.

Description

Technical Field

[0001] The utility model relates to the field of large-diameter pile foundation hole-forming machinery and equipment, in particular to a pilot step-type roller cutter bit used for constructing large-diameter rock-embedded piles. Background Art

[0002] At present, large buildings or structures generally use large-diameter rock-embedded piles as pile foundations. The pile diameter of this type of pile is generally more than 2m, and the rock layer is required to be the bearing layer, so a large roller cutter is needed to break the rock and drill. In addition, except for a few terrains such as the Gobi Desert where the rock layer is directly exposed, most other rock layers are covered with soil layers, sand layers, gravel layers and other covering layers. Direct drilling with a roller cutter will cause drilling jams, so a scraper drill is used to drill downward from the ground first, and the roller cutter is replaced after the pile hole passes through the covering layer and reaches the surface of the rock layer, and then the roller cutter continues to drill downward to break the rock.

[0003] The traditional roller cutter drill bit includes a cutter disc connected to a drill rod, and a plurality of roller cutters are rotatably mounted on the bottom surface of the cutter disc. A slag discharge channel is provided inside the cutter disc, and the slag discharge channel is connected to the inner cavity of the drill rod. The slag discharge port of the slag discharge channel is located on the bottom surface of the cutter disc. When the roller cutter drill bit is drilling, it relies on the roller cutters on the bottom surface of the cutter disc to grind and crush the drill, and sucks the drill cuttings from the slag discharge port and discharges them from the hole along the slag discharge channel and the inner cavity of the drill rod. The disadvantage of the above-mentioned traditional roller cutter drill bit is that it frequently deflects when facing hard and inclined rock surfaces.

[0004] In order to improve the situation of drilling deviation, our company has designed a pilot step type roller cutter drill bit, see patent number CN202020572168.0. The drill bit adds a downward convex pilot step surface on the bottom surface of the cutter disc, and a second roller cutter is also installed on the bottom surface of the pilot step surface. In this way, when drilling, the pilot step surface contacts the rock formation first, which reduces the contact area between the drill bit and the rock formation and increases the pressure, thereby obtaining a greater rock breaking drilling efficiency, and the first roller cutter on the bottom surface of the cutter disc follows up to achieve secondary crushing, and the designers hope that the pilot step will play a positioning and guiding role to ensure that the drill bit drills vertically.

[0005] However, engineering and technical personnel have discovered in the long-term actual construction process that the straightening and guiding effect of the above-mentioned drill bit is not ideal. The main reason is that the various rollers of the cutter disc are arranged in a staggered manner and are worn, so it is difficult to keep the center of gravity in the middle, and the extra-long drill rod itself will also oscillate centrifugally. Therefore, the superposition of the two phases makes it impossible for the cutter disc to rotate concentrically driven by the drill rod, and it will continue to shake and vibrate, and transmit the shaking and vibration to the pilot step surface, making the pilot step surface even more prone to deflection during drilling on an inclined hard rock surface. Utility Model Content

[0006] The technical problem to be solved by the utility model is to provide a pilot step type roller cutter drill which has better straightening effect and can effectively avoid tilting drilling.

[0007] The technical solution of the utility model is to provide a pilot step-type roller cutter drill, which comprises a cutter disc and a flange for connecting a drill rod, the cutter disc comprises a side wall and a bottom ring surface, the bottom ring surface is welded to the lower end of the side wall, and a first roller cutter is rotatably installed on the bottom ring surface; the center of the bottom ring surface is welded to the bottom end of a guide sleeve, and the guide sleeve is vertically slidably matched with an inner cylinder drill, and a second roller cutter is rotatably installed on the bottom surface of the inner cylinder drill; at least two lugs are protruding from the outer wall of the inner cylinder drill, and the outer diameter of the lugs is equal to the inner diameter of the guide sleeve; a top cover for limiting the upper limit position of the inner cylinder drill is welded on the upper end of the guide sleeve, and a clamping ring for supporting the lugs to limit the lower limit position of the inner cylinder drill is provided at the lower end of the inner wall of the guide sleeve; the inner cylinder drill is connected to the flange through a core tube, and the core tube passes through the center hole of the top cover; a fan ring clamping strip for abutting against the end of the lug to transmit torque from the inner cylinder drill to the cutter disc is welded on the upper ring surface of the clamping ring and the inner wall of the guide sleeve.

[0008] Compared with the prior art, the pilot step type roller cutter bit adopting the above structure has the following advantages.

[0009] The working process of the drill is as follows.

[0010] First, use a scraper drill bit to drill a hole in the overburden layer until it reaches the surface of the rock formation, then lift the drill rod and replace it with the pilot stepped roller cutter bit of the present application, and then lower it into the pile hole; during the lowering process, the cutter head cover is placed on the inner barrel drill, and when the drill bit is lowered to the bottom of the hole, the outer cutter head touches the inclined rock surface and is blocked and no longer descends, but the inner barrel drill in the middle continues to move downward under the torque and downward pressure of the drill rod and drills into the rock, thus forming a state in which the outer cutter head is stationary and the inner drill barrel is drilling downward, i.e., a straightening drilling state, ... The side wall of the disc firmly supports the side wall of the pile hole, and the inner drill barrel is effectively straightened through the guide sleeve and the lug, ensuring that the inner drill barrel overcomes the reaction force of the inclined rock formation and drills vertically; since the contact area between the inner drill barrel and the rock formation is small and the pressure is strong, the rock breaking drilling efficiency is high, and the outer cutter disc always remains stationary during the process of supporting the inner drill barrel, and is not affected by the centrifugal swing of the drill rod, and will not shake or oscillate. It is a real static buttress, so the outer cutter disc forms a continuous, stable, balanced and powerful straightening force on the inner barrel drill, ensuring that the inner barrel drill drills vertically downward into the rock formation. The above-mentioned straightening drilling state will continue stably for a period of time until the top of the inner barrel drill drops to the lower mouth of the cutter disc. At this time, the lug presses the clamping ring and the end of the lug abuts against the fan ring clamping strip, thereby transmitting the torque of the inner barrel drill to the outer cutter disc, and also transmitting the downward force to the outer cutter disc, so that the inner barrel drill and the outer cutter disc are synchronously drilled in an inverted convex shape. In this state, the inner barrel drill convexly performs primary crushing first, and the first roller on the bottom surface of the cutter disc follows up for secondary crushing. Since the primary crushing releases the rock formation stress, the efficiency of the secondary follow-up crushing is also significantly improved; the inverted convex shape is maintained for synchronous drilling until the pile bottom elevation is reached.

[0011] From the above analysis, it can be seen that when the drill bit encounters an inclined rock surface, the inner barrel drill and the cutter disc do not transmit torque, so that the cutter disc is not affected by the centrifugal swing of the drill rod, and is firmly supported against the wall of the pile hole. The cutter disc itself will not shake or vibrate, so a true static buttress is achieved, and the straightening effect is better, which can effectively avoid inclined drilling and ensure vertical hole formation; and the inner barrel drill vertically penetrates into the rock formation for a certain distance, so that the overall verticality of the drilling process in the rock formation is guaranteed, and then the torque transmission of the inner barrel drill and the cutter disc can be reconnected, so that the two can drill synchronously in an inverted convex shape to obtain excellent rock breaking efficiency and ensure a sufficiently large hole forming cross-sectional area.

[0012] Preferably, a slag discharge pipe is provided in the core tube, the upper end of which is connected to the drill pipe through the center hole of the flange; a slag suction bent pipe is provided at the lower end of the slag discharge pipe, and the inlet of the slag suction bent pipe is located at the bottom plate of the inner tube drill; in this way, the inlet of the slag discharge channel is offset from the center of the inner tube drill, and forms a slag suction annular belt as the inner tube drill rotates, thereby increasing the slag suction area and covering more areas of the bottom cross-section of the hole.

[0013] As another preferred embodiment, the lower end of the core tube is welded to the top plate of the inner tube drill, the upper end of the slag discharge pipe is welded to the flange, the middle section of the slag discharge pipe passes through the top plate of the inner tube drill and is welded to the center hole of the top plate of the inner tube drill, and the lower end of the slag discharge pipe is welded to the bottom plate of the inner tube drill; in this way, the structural strength and integrity of the inner tube drill are effectively enhanced, making it more solid and having a longer service life.

[0014] As a further preference, the side walls of the cutter disc, the bottom annular surface of the cutter disc and the outer wall of the guide sleeve are welded with wedge-shaped ribs; a conical closing plate is welded with the upper end of the side wall of the cutter disc, and the conical closing plate is also welded to the upper end of a circle of wedge-shaped ribs; in this way, the integrity and firmness of the cutter disc structure can be enhanced, making it stronger and more durable; the conical closing plate makes the lifting process of the drill bit smoother and more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The utility model is a structural schematic diagram of a cutter head of a pilot step type roller cutter drill bit when it is hung on an inner drill tube.

[0016] Figure 2 yes Figure 1 Schematic diagram of the structure after deflection at a certain angle.

[0017] Figure 3 The utility model is a structural schematic diagram of a pilot stepped roller cutter drill bit in an inverted convex drilling state.

[0018] Figure 4 It is an exploded schematic diagram of a pilot step type roller cutter drill bit of the utility model.

[0019] Figure 5 The utility model is a schematic diagram of the structure of the cutter head of the pilot step type roller cutter drill bit.

[0020] Figure 6 It is a schematic diagram of a pilot step-type roller cutter drill bit of the utility model after half-section and decomposition.

[0021] Figure 7 Yes Yes Figure 6 Schematic diagram of the structure after deflection at a certain angle.

[0022] Figure 8 It is a side structural schematic diagram of the utility model in the inverted convex drilling state of the drill bit.

[0023] As shown in the figure, 1. cutter disc, 1.1. side wall, 1.2. bottom ring surface, 2. flange, 3. first hob, 4. guide sleeve, 5. wedge-shaped rib, 6. tapered closing plate, 7. inner tube drill, 7.1. top plate, 7.2. bottom plate, 8. second hob, 9. lug, 10. top cover, 11. clamping ring, 12. core tube, 13. slag discharge pipe, 14. slag suction elbow, 15. fan ring clamping strip. DETAILED DESCRIPTION

[0024] The utility model is further described below in conjunction with the accompanying drawings and specific embodiments.

[0025] like Figures 1 to 8 As shown, the pilot step type roller cutter drill bit of the utility model comprises a cutter disc 1 and a flange 2. The flange 2 is a lower flange, and an upper flange is welded to the lower end of the drill rod. The upper and lower flanges are screwed. The cutter disc 1 comprises a side wall 1.1 and a bottom ring surface 1.2. The outer edge of the bottom ring surface 1.2 is welded to the lower end of the side wall 1.1. The bottom ring surface 1.2 is a conical surface with a lower inner side and a higher outer side. Its function is to guide the drill cuttings during drilling so that they are discharged from the inside to the outside. The bottom ring surface 1.2 is rotatably mounted with a plurality of first roller cutters 3.

[0026] The center of the bottom ring surface 1.2 of the cutter disc 1 is welded to the bottom end of a guide sleeve 4, and a circle of multiple wedge-shaped ribs 5 are welded together with the side wall 1.1 of the cutter disc 1, the bottom ring surface 1.2 of the cutter disc 1 and the outer wall of the guide sleeve 4; a conical closing plate 6 is welded to the upper end of the side wall 1.1 of the cutter disc 1, and the conical closing plate 6 is also welded to the upper end of a circle of multiple wedge-shaped ribs 5.

[0027] The guide sleeve 4 is vertically slidably matched with an inner cylinder drill 7, and a plurality of second roller cutters 8 are rotatably mounted on the bottom surface of the inner cylinder drill 7. The guide sleeve 4 is slightly higher than the inner cylinder drill 7. The outer wall of the inner cylinder drill 7 has at least two lugs 9 protruding outwardly. The lugs 9 of the present application are two and symmetrical; the outer diameter of the lugs 9 is equal to the inner diameter of the guide sleeve 4. A top cover 10 for limiting the upper limit position of the inner cylinder drill 7 is welded to the upper end of the guide sleeve 4, and a clamping ring 11 for supporting the lugs 9 to limit the lower limit position of the inner cylinder drill 7 is provided at the lower end of the inner wall of the guide sleeve 4. The lugs 9 are limited to the height range between the cover plate and the clamping ring 11.

[0028] The inner tube drill 7 is connected to the flange 2 via a core tube 12, the lower end of the core tube 12 is welded to the top plate 7.1 of the inner tube drill 7, the middle section of the core tube 12 passes through the center hole of the top cover 10, and the upper end of the core tube 12 is welded to the flange 2. A slag discharge pipe 13 is arranged in the core tube 12, and the upper end of the slag discharge pipe 13 is connected to the drill rod through the center hole of the flange 2; a slag suction elbow 14 is arranged at the lower end of the slag discharge pipe 13, and the entrance of the slag suction elbow 14 is located at the bottom plate 7.2 of the inner tube drill 7. The upper end of the slag discharge pipe 13 is welded to the flange 2, the middle section of the slag discharge pipe 13 passes through the top plate 7.1 of the inner tube drill 7 and is welded to the center hole of the top plate 7.1 of the inner tube drill 7, and the lower end of the slag discharge pipe 13 is welded to the bottom plate 7.2 of the inner tube drill 7.

[0029] The upper annular surface of the clamp ring 11 and the inner wall of the guide sleeve 4 are welded together with a fan ring clamp strip 15 for abutting against the end of the lug 9 to transmit the torque from the inner barrel drill 7 to the guide sleeve 4 and the cutter head 1. In other words, the outer arc surface of the fan ring clamp strip 15 is welded to the inner wall of the guide sleeve 4 and the bottom surface of the fan ring clamp strip 15 is welded to the upper annular surface of the clamp ring 11.

[0030] Of course, in order to ensure stable and reliable transmission of torque between the inner barrel drill and the cutter disc, the height, width and thickness of the lugs will be specifically increased to increase the welding contact area between the lugs and the inner barrel drill; similarly, the height, width and thickness of the fan ring clip will be increased, and the height and thickness of the clip ring will be increased, so as to increase the welding contact area between the fan ring clip and the clip ring and the guide sleeve; of course, the number of lugs and fan ring clips can also be increased, such as setting four lugs, or six lugs, to increase the firmness of the transmission structure and the stability of torque transmission. Even, the lugs can be screwed to the inner barrel wall of the inner barrel drill with high-strength bolts, or the fan ring clip can be screwed to the inner wall of the guide sleeve with high-strength bolts.

[0031] The drill bit of the present application has three states.

[0032] State 1, the outer cutter disc 1 is suspended on the inner drill tube, that is, the top cover 10 of the cutter disc 1 is placed and suspended on the top plate 7.1 of the inner drill tube 7.

[0033] State 2, static straightening, the outer cutter head 1 is stuck to the wall of the pile hole and does not move, and the inner drill tube 7 drills downward to break the rock under the action of the drill rod until the lug 9 of the inner drill tube 7 abuts against the clamping ring 11.

[0034] In state 3, the inner barrel drill 7 and the cutter head 1 drill synchronously in an inverted convex shape. At this time, the lug 9 of the inner barrel drill 7 abuts against the clamping ring 11 and the fan ring clamping strip 15 at the same time.

[0035] When the drill reaches the bottom elevation, the drill head is lifted out of the hole, so that the top cover 10 of the cutter head 1 is placed on the top plate 7.1 of the inner tube drill 7 again, and the state 1 is returned.

Claims

1. A pilot step type roller cutter drill bit, comprising a cutter head and a flange for connecting a drill rod, wherein the cutter head comprises a side wall and a bottom ring surface, wherein the bottom ring surface is welded to the lower end of the side wall, and a first roller cutter is rotatably mounted on the bottom ring surface; characterized in that: The center of the bottom annular surface is welded to the bottom end of a guide sleeve, and the guide sleeve is fitted with an inner cylinder drill in a vertical sliding manner, and a second roller is rotatably installed on the bottom surface of the inner cylinder drill; at least two lugs are protruding from the outer wall of the inner cylinder drill, and the outer diameter of the lugs is equal to the inner diameter of the guide sleeve; a top cover for limiting the upper limit position of the inner cylinder drill is welded to the upper end of the guide sleeve, and a clamping ring for supporting the lugs to limit the lower limit position of the inner cylinder drill is provided at the lower end of the inner wall of the guide sleeve; the inner cylinder drill is connected to the flange via a core tube, and the core tube passes through the center hole of the top cover; a fan ring clamping strip for abutting against the end of the lug to transmit torque from the inner cylinder drill to the cutter disc is welded to the upper annular surface of the clamping ring and the inner wall of the guide sleeve.

2. The pilot step type roller cutter drill bit according to claim 1, characterized in that: A slag discharge pipe is arranged in the core tube, and the upper end of the slag discharge pipe is connected with the drill pipe through the center hole of the flange; a slag suction elbow is arranged at the lower end of the slag discharge pipe, and the inlet of the slag suction elbow is located at the bottom plate of the inner tube drill.

3. The pilot step type roller cutter drill bit according to claim 2, characterized in that: The lower end of the core tube is welded to the top plate of the inner tube drill, the upper end of the slag discharge pipe is welded to the flange, the middle section of the slag discharge pipe passes through the top plate of the inner tube drill and is welded to the center hole of the top plate of the inner tube drill, and the lower end of the slag discharge pipe is welded to the bottom plate of the inner tube drill.

4. The pilot step type roller cutter drill bit according to claim 1, characterized in that: The cutter disc side wall, the cutter disc bottom ring surface and the outer wall of the guide sleeve are welded with wedge-shaped ribs; the upper end of the cutter disc side wall is welded with a conical closing plate, which is also welded to the upper end of a circle of wedge-shaped ribs.

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