Roller bit for rock breaking by rotary cutting

Abstract

A roller bit for rock breaking by rotary cutting comprises: a bit body (1), a roller (2) and cutting teeth (3). An included angle β between a roller journal plane of the bit body and the roller on a bit axis has a range of 0°<β<90°, a journal offset S has a range of −D/2<S<D/2, wherein D represents a diameter of the bit. Inner row of teeth rings on the bit cuts a center of a borehole bottom, and each row of teeth ring is capable of scraping a borehole wall, and thus the bit has good effects of gauge protection and sidetracking.

Claims

1. A roller bit for rock breaking by rotary cutting comprising: a bit body (1), a roller (2) and cutting teeth (3) provided on a working face of the roller (2), wherein an included angle between a roller journal plane of the bit body (1) and a roller body on a bit axis is denoted as β, β=30°, a journal offset is denoted as S, S=D/20, a diameter D=4.75″, a drilling rate n=180 rpm, wherein D represents a diameter of the bit; wherein said included angle between said roller journal plane and said roller body on said bit axis, β.sub.i=β.sub.i+1 or β.sub.i≠β.sub.i+1, said journal offset s.sub.i=s.sub.i+1 or s.sub.i≠s.sub.i+1, wherein i represents a sequence number of said roller (i≧1), said included angle β.sub.i of said roller body is corresponding an ith roller and said journal offset Si is corresponding to said ith roller; a cone/bit speed ratio, which is a ratio of a rotating speed of said roller to said bit, of said roller bit by rotary cutting is less than 1; a motion trail of teeth of at least single roller reaches or crosses a position of an axis of said bit.

2. A roller bit for rock breaking by rotary cutting comprising: a bit body (1), a roller (2) and cutting teeth (3) provided on a working face of the roller (2), wherein an included angle β between a roller journal plane of the bit body (1) and a roller body on a bit axis is denoted as β, β=30°, a journal offset is denoted as S, S=−D/20, a diameter D=4.75″, a drilling rate n=180 rpm, wherein D represents a diameter of the bit; wherein said included angle between said roller journal plane and said roller body on said bit axis, β.sub.i=β.sub.i+1 or β.sub.i≠β.sub.i+1, said journal offset s.sub.i=s.sub.i+1 or s.sub.i≠s.sub.i+1, wherein i represents a sequence number of said roller (i≧1), said included angle β.sub.i of said roller body is corresponding an ith roller and said journal offset Si is corresponding to said ith roller; a cone/bit speed ratio, which is a ratio of a rotating speed of said roller to said bit, of said roller bit by rotary cutting is less than 1; a motion trail of teeth of at least single roller reaches or crosses a position of an axis of said bit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a structural schematic view of a double-roller bit adopted by the present invention, which comprises: a bit body (1), a roller (2), cutting teeth (3), a oil storage tank (4) and a nozzle (5). The bit body (1) comprises: a roller journal, a wiper block, a high-pressure slurry channel and a screw thread for connecting. The journal of the roller (2) and the bit body (1) utilizes a bearing and sealing structure commonly used in conventional three roller bits, and a plurality of cutting teeth rings are provided from a large end to a small end of the roller.

(2) FIG. 2 is a schematic view of a cutting principle and relationships of main designed parameters of the present invention comprising an included angle β of the roller body, a journal offset S and diameter of the bit.

(3) FIG. 3 is a structural schematic view of a crown, wherein a number of the roller is 2, the included angle β of the roller body=30°, the journal offset S=D/20, and one of the roller cuts a center and the other roller does not cut the center.

(4) FIG. 4 is a projection schematic view of teeth rings of the rollers, wherein a number of the roller is 2, the included angle of the roller body β=30°, the journal offset S=0, and both of the rollers cut the center.

(5) FIG. 5 is a projection schematic view of teeth rings of the rollers, wherein a number of the roller is 2, the included angle of the roller body β=89.50°, the journal offset S=0, and both of the rollers cut the center.

(6) FIG. 6 is a projection schematic view of teeth rings of the rollers, wherein a number of the roller is 1, the included angle of the roller body β=30°, the journal offset S=D/20, and the roller cut the center.

(7) FIG. 7 is a projection schematic view of teeth rings of the rollers, wherein a number of the roller is 2, the included angle of the roller body β=30°, the journal offset S=D/20, and one of the roller cuts the center and the other roller does not cut the center.

(8) FIG. 8 is a projection schematic view of teeth rings of the rollers, wherein a number of the roller is 2, the included angle of the roller body β=30°, the journal offset S=D/20, and both of the rollers do not cut the center.

(9) FIG. 9 is a projection schematic view of teeth rings of the rollers, wherein a number of the roller is 3, the included angle of the roller body β=30°, the journal offset S=D/20, and all of the three rollers do not cut the center.

(10) These and other objectives, features, and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(11) Referring to FIGS. 1-9 of the drawings, a roller bit for rock breaking by rotary cutting, comprises: a bit body (1), a roller (2), cutting teeth (3), a oil storage tank (4) and a nozzle (5). The bit body (1) comprises: a roller journal, a wiper block, a high-pressure slurry channel and a screw thread for connecting. The journal of the roller (2) are rotatablely connected with the roller journal of the bit body (1) utilizing a bearing and sealing structure commonly used in conventional three roller bits. A plurality of cutting teeth rings are provided from a large end to a small end of the roller (2).

(12) An included angle β between the roller journal plane and the roller body on said bit axis, which is called included angle of the roller body, has a rang of 0°<β<90° β.sub.i=β.sub.i+1 or β.sub.i≠β.sub.i+1: an journal offset S has a range of D/2<S<D/2, wherein s.sub.i=s.sub.i+1 or s.sub.i≠s.sub.i+1, wherein β.sub.i is an included angle of the roller body corresponding to a roller i, S.sub.i is a journal offset corresponding to the roller i, and D represents a diameter of the bit.

Embodiment 1

(13) In the rotary cutting bit of the present invention, β=30°, S=D/20, a diameter D=4.75″, a drilling rate n=180 rpm, experimental materials respectively utilize rocks of Hongya County with a size of 225×200×150 mm.sup.3 and green sandstone with a size of 150×150×100 mm.sup.3. During the process of the experiment, collect rock chip, analyze difficulty of the rock breaking and the vibration thereof, check wear marks of the cutting teeth and directions thereof, calculate a cone/bit speed ratio of the roller and the bit.

(14) Both experimental results and theoretical calculation indicate that under the condition of parameters in the embodiment 1, the cone/bit speed ratio is less than 1, and actually in this embodiment, the cone/bit speed ratio is less than 0.55. The harder the rock, the higher the rotating speed of the roller and the cone/bit speed ratio.

Embodiment 2

(15) In the rotary cutting bit of the present invention, β=30°, S=−D/20, a diameter D=4.75″, a drilling rate n=180 rpm, experimental materials respectively utilize rocks of Hongya County with a size of 225×200×150 mm.sup.3 and green sandstone with a size of 150×150×100 mm.sup.3. During the process of the experiment, collect rock chip, analyze difficulty of the rock breaking and the vibration thereof, check wear marks of the cutting teeth and directions thereof, and calculate a cone/bit speed ratio of the roller and the bit.

(16) Both experimental results and theoretical calculation indicate that: when S=−D/20, the harder the rock, the lower the rotating speed of the roller, and the cone/bit speed ratio in this embodiment is less than corresponding value in the embodiment 1.

(17) Based on comprehensive and comparative analysis of the embodiment results mentioned above, it can be concluded that optimizing the included angle β of the roller body and the journal offset S is capable of achieving objects of increasing the sliding distance of the cutting teeth of the roller on the bottom and wall of the borehole and decreasing a cone/bit speed ratio of the roller body, so as to improve rock breaking efficiency of the rotary bit and the penetration rate.

Embodiment 3

Single Roller Bit

(18) Working face of the roller faces between the wall and the bottom of the borehole. An included angle β between a roller journal plane of the bit body (1) and a roller body on a bit axis has a range of 0°<β<90°, a journal offset S has a range of −D/2<S<D/2, wherein the large teeth ring of the roller cuts the center.

(19) One skilled in the art will understand that the embodiment of the present invention as shown in the drawings and described above is exemplary only and not intended to be limiting.

(20) It will thus be seen that the objects of the present invention have been fully and effectively accomplished. Its embodiments have been shown and described for the purposes of illustrating the functional and structural principles of the present invention and is subject to change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.