JP3096842U - Rotary cutter lock bit device with pressure balance device - Google Patents

Abstract

A rotary cutter lock bit device with a pressure balance device that is capable of more sufficiently preventing infiltration of mud from the outside to the inside by providing a double seal structure between a bearing shaft and a cutter. I will provide a.
A plurality of bearing shafts, a cutter rotatably mounted on the bearing shaft, an annular seal for shielding the bearing shaft and the cutter from the outside, and an internal pressure between the bearing shaft and the cutter are provided. In a rotary cutter lock bit device provided with a pressure balance device for balancing external pressure, the pressure balance device has a rubber inner annular seal and an outer annular seal, and the outer annular seal includes a metal rigid ring. Including, the metal ring is performed by this rigid ring.
[Selection] Fig. 2

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a rotary cutter lock bit device with a pressure balance device used for drilling a well such as an oil well, a gas well, a geothermal well, a hot spring well, and a water well.
[0002]
[Prior art]
Conventionally, a rotary cutter lock bit with a pressure balance device generally used for well drilling is provided with three bearing shafts, and a cutter is rotatably mounted on each of the bearing shafts ( For example, see Patent Literature 1, Patent Literature 2, and Patent Literature 3.) The bearing shaft is filled with grease so that the cutter can rotate smoothly, and wear of the bearing shaft is prevented. In the gap between the bearing shaft and the cutter, grease is prevented from flowing out from inside the bearing to the outside, and drilling mud circulating in the well is prevented from entering the bearing from outside. Generally, a rubber annular seal is fitted in the annular gap.
[0003]
Further, a pressure balance device having a diaphragm is provided in order to balance the fluid pressure of the well applied to the lock bit device with the internal pressure of the lock bit device. This pressure balance device prevents the seal ring from being pushed into the interior by compressing the compressible air inevitably remaining in the grease inside the bit device by an external pressure, and at the same time the bearing while the lock bit is used. Prevents the seal ring from being pushed outward due to grease expansion and decomposition gas generation due to partial heating. (See Patent Documents 1 and 2.)
[0004]
[Patent Document 1]
US Patent No. 3,075,781 [Patent Document 2]
US Patent No. 3,370,895 [Patent Document 1]
US Patent No. 4,722,404
[Problems to be solved by the invention]
In this type of rock bit device, drilling mud sent from a ground through a drill string is jetted from a nozzle attached to the rock bit device toward the downhole, and this jet flow is cut together with the cuttings generated at the bottom by a cutter. Between the drill string and the pit wall. As a result of violent jet flow, the drilling mud containing cuttings penetrates into the annular seal placement through the gap between the bearing shaft and the cutter, causing the annular seal to wear and, in addition, being embedded in the annular seal There is a problem that the cutting wastes wear the bearing shaft.
[0006]
That is, as the wear of the rubber annular seal and the bearing shaft progresses, the seal interference decreases, and as a result, the grease flows out to the outside due to the swinging of the cutter accompanying the excavation, and the drilling mud enters from the outside toward the inside. This rapidly wears the bearing shaft, necessitating replacement of the lock bit device.
Accordingly, there is a need for an improvement that extends the life of the annular seal so as to substantially extend the life of the bearing shaft.
[0007]
The present invention has been made in view of the above problems, and by providing a double seal structure between a bearing shaft and a cutter, it is possible to more sufficiently prevent infiltration of muddy water from the outside to the inside. It is an object of the present invention to provide a rotary cutter lock bit device with a pressure balance device that can be used.
[0008]
Further, another object of the present invention is to provide a metal seal for the outer annular seal of the double seal structure, and obtain a higher sealing performance by obtaining the contact pressure by two-stage pressurization. To provide a rotary cutter device with a pressure balance device.
[0009]
[Means for Solving the Problems]
In order to achieve the first object, in a rotary cutter lock bit device with a pressure balance device according to the present invention, a plurality of bearing shafts, a cutter rotatably mounted on the bearing shaft, and a space between the bearing shaft and the cutter are provided. A rotary cutter lock bit device provided with an annular seal for shielding the outside from the outside and a pressure balance device for balancing the internal pressure between the bearing shaft and the cutter with the external pressure, wherein the pressure balance device is made of rubber. It has an inner annular seal and an outer annular seal, and the outer annular seal is made of a metal rigid ring, and the metal seal is performed by the rigid ring.
[0010]
Further, in order to achieve the second object, in the rotary cutter lock bit device provided with the pressure balance device according to the present invention, in order to obtain the contact pressure of the metal seal of the outer annular seal, pressurization by an elastic material is performed. It is characterized by being performed.
[0011]
In the rotary cutter lock bit device with a pressure balance device, the rigid ring is pressurized by a combination of a rubber material and a metal spring.
[0012]
Further, in this rotary cutter lock bit device with a pressure balance device, the rubber material is a fluorine-based rubber material or a nitrile rubber material, and the metal spring is a disc spring or a wavy disc spring.
[0013]
[Effect of the invention]
With the above configuration, the rotary cutter lock bit device with the pressure balance device according to the present invention is provided with an outer annular seal formed of another rigid ring outside the conventional rubber annular seal (outside of the muddy water). Due to the heavy sealing structure, it is possible to prevent muddy water from entering from the outside to the inside.
[0014]
In addition, the outer annular seal that forms a double seal structure has a metal rigid ring, performs a metal seal between the bearing shaft and the rotary cutter, and reduces the contact pressure by a rubber or metal spring. In the bearing space where the bit device is limited, it is important to minimize the seal arrangement space, and the smaller this space is, the more the swing due to play in the cutter axial direction becomes more problematic. The followability of the metal seal surface against the pressure is greatly improved compared to the seal by pressurization alone since the metal seal pressing force is performed by the pressing force of the rubber and the metal spring.
[0015]
Further, when used for a geothermal well bit exposed to high temperatures, the reduction of the elastic force of the rubber material due to compression permanent deformation is reinforced by a metal spring, and the effect of extending the life of the seal can be obtained.
[0016]
[Embodiment of the invention]
In the means for solving the above-mentioned problem, the outer annular seal is disposed outside the rubber annular seal in a gap formed between the root of the bearing shaft and the rotary cutter. The outer annular seal includes an inner diameter fitting portion, a metal spring, a pressing portion made of backup rubber, and a rigid ring.
[0017]
The inner diameter fitting portion of the outer annular seal is a portion which is fitted to the root portion of the body journal shaft by means of press-fitting, bonding, or the like, and usually has a fixing function that does not rotate or slide relative to the journal shaft, and It has a fluid sealing function that does not allow the in-well fluid to pass.
[0018]
The axial contact pressure between the rigid ring of the outer annular seal and the sliding surface of the cutter seal facing the rigid ring is maintained by pressurization by an elastic material such as rubber or a metal spring.
[0019]
The elastic material for pressurization is considered to be most preferably a fluoro rubber, for example, AFLAS, but a nitrile rubber material such as NBR or H-NBR may be used. The metal spring for pressurization includes a conventional disc spring (Belleville Spring Seal) or a corrugated disc spring (Corrugated Spring Seal).
[0020]
In addition, the backup rubber prevents the relative movement between the back of the body-shart tail and the outer metal seal, and also serves to seal downhole fluid.
[0021]
Furthermore, it is desirable to provide a device for balancing the pressure in the gap between the inner annular seal and the outer annular seal with the downhole pressure or the bit bearing pressure.
[0022]
【Example】
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a partial cross-sectional perspective view showing a rotary cutter lock bit device 10 with a pressure balance device according to the present invention, and two of three rotary cutters 22 are shown.
[0023]
The bearing shaft 20 of the rotary cutter lock bit device 10 is integrally provided at an end of a drill body 12 which is attached by screwing into a string of a drill pipe (not shown) so as to extend obliquely downward toward the center. As shown in the cross-sectional view of FIG. 2, the rotary cutter 22 which is rotatably supported by the bearing shaft 20 has an outer surface formed in a substantially conical shape, and is fixedly attached by embedding a large number of cutting teeth 18 therein. It is mounted on the rotating shaft 20 via a sliding ball 70 and via a holding ball 26 fitted between a ball holding groove 24 formed on the shaft 20 and a corresponding holding groove 28 on the rotary cutter 22 side.
[0024]
The rotary cutter 22 is provided with drilling mud and shavings, which are fluids in a downhole, and a lubricant filled between the rotary cutter 22 and the rotary shaft 20 on the inner wall of the drill hole on the inner wall of the mounting hole to the rotary shaft 20. A seal is provided so as to block the ingress and egress. This seal is provided as shown in the circle of FIG. 2, and more specifically, as shown in FIG. 3, an inner annular seal 30 made of rubber and an outer seal provided closer to the outside of the bit body 12 than this. An annular seal 32 is provided.
[0025]
The space 34 between the inner annular seal 30 and the outer annular seal 32 and the outside of the bit are provided between the space 34 and the outside of the bit in order to balance the pressure there. A pressure balancing device 42 is provided via a passage 40 as shown in FIG. The pressure balance device 42 is adapted to cope with a pressure difference between the space 34 and the outside of the bit by moving a rubber ball 46 in a cylinder 44 machined with high precision. Such an inner elastic seal 30 is subjected to vacuum suction, grease pressurization, and decompression in order to fill the lubricant into the bearing at the time of assembling the bit. At this time, the inner annular seal 32 is moved in the axial direction of the bearing shaft 20. After being deformed according to the movement to, it can return to a normal position.
[0026]
Such a double seal structure is shown in FIG. 3 (the portion within the circle in FIG. 2), in which the inner annular seal 30 is provided at the opening of the rotary cutter 22 as shown in FIGS. This is provided by providing an O-ring, which is a rubber seal, housed in an annular groove formed in the inner peripheral wall in a compressed state so as to provide a sealing effect to the outer peripheral surface of the rotating shaft 20. The inner annular seal 30 employs an O-ring, but the cross-sectional shape is not limited to a circle, and may have various cross-sectional shapes. Also, the inner annular seal 30 is designed to withstand large cutter swings to substantially completely prevent drilling mud entering the bearings through the outer annular seal 32 from entering between the seals. They are fitted with a relatively large interference.
[0027]
As shown in FIG. 3 and FIG. 4 showing a further portion thereof, the outer annular seal 32 in the double seal structure has a shears tail rear surface 68 of the bearing shaft 20 and a rotary cutter 22 at the end face of the rotary cutter 22. In the space 32 formed by the sliding surface 62, a rigid ring 60 is provided in a radial direction of the sliding surface 62 to provide a metal seal. A spring 52 is housed in the inner diameter mating portion 50 to form part of the pressurization while at the same time contacting the back end 68 of the shears tail so that the backup rubber 54 is positioned to form another pressurizing portion of the rigid ring 60. It is provided in.
[0028]
The rigid ring 60 has a radially processed surface 62 in a radial direction, and is provided so as to be in sealing contact with a radially directed surface 64 formed in the opening of the rotary cutter 22. During the operation of the bit 10, the sliding surface 62 of the rigid ring 60 is used to reduce the abrasion that occurs when the rotary cutter 22 rotates and slides with a rotary seal in drilling mud containing cuttings. It is preferably made of a wear resistant hard metal or coated with a hard material, such as cemented carbide, stellite, or hardened steel containing dispersed carbides, and should not be rotationally sealed with the rigid ring 60. The radial surface 64 of the opening of the sliding rotary cutter 22 is also a smoothed surface, and a heat treatment such as carburization or a surface treatment such as coating is performed to improve abrasion resistance. It is desirable.
[0029]
In addition, a corrugated disc spring 52 (detailed in FIG. 6) is embedded in the pressing portion 52 as a metal spring 52 as shown in FIG. 4 and is integrally formed, so that the rigid ring 60 can be further pressed. . The backup rubber 54 is not shown in the drawing so as to be distinguished from the material of the other parts as the pressurizing part 56, but another kind of elastic material may be used. And the backup rubber 54 may be separated. In this case, it is desirable that the rigid ring 60 and the backup rubber 54 be joined with an adhesive or the like so as to maintain the sealing property of the contact boundary surface and prevent relative rotation, but it is not always necessary.
[0030]
The inner diameter fitting portion 50 of the pressurizing portion 56 is a portion fitted into the bearing shaft 20 as described above, but is formed of rubber or the like so as not to rotate relative to the bearing shaft 20 when the bit is operated. Is fixed by interference fit.
[0031]
Further, as shown in FIGS. 3 to 5, the corrugated disc spring 52 in the pressurizing portion 56 is provided between the radial surface 64 of the rotary cutter 22 and the radial surface 62 of the rigid ring 60 in a sealing contact. A corrugated disc spring 52 is provided as shown in FIG. The corrugated disc spring 52 can be designed to have a relatively flat portion in the load-deflection curve in order to cope with the axial clearance which is difficult to control as compared with the radial clearance of the rotary cutter 22. Even when the rotary cutter 22 swings in the axial direction and the deflection of the spring changes greatly, the change in the spring pressure, that is, the change in the seal contact surface pressure can be reduced.
[0032]
Further, as shown in FIG. 3, the backup rubber 54 of the pressurizing portion 52 reduces the seal contact pressure between the radial surface 62 of the rigid ring 60 and the radial surface 64 at the opening of the rotary cutter 22. The distribution is adjusted, and the shape is generally determined so that the surface pressure on the outer diameter drilling mud side is larger than that on the inner diameter grease side. Then, the backup rubber 54 is compressed between the rigid ring 60 and the back of the seats tail 68 to apply a sealing contact pressure, and the friction between the backup rubber 54 and the back of the shears tail 68 causes an outer annular seal. It serves to prevent relative movement between the shaft 32 and the bearing shaft 20.
[0033]
The pressing portion 56 of the outer annular seal 32 shown in FIG. 5 is in a state before being positioned with respect to the rigid ring 60 and the rotating shaft 20, and a part of the cut portion is shown. In this state, the rigid ring 20 and the pressurizing portion 56 are shown as separate parts, but they may be integrally formed.
[0034]
Further, the corrugated disc spring 52 of the metal spring integrally embedded in the inner diameter fitting portion 50 of the pressurizing portion 56 is in a state of being integrated in FIG. 5 and in a state of being actually disposed in the space 34 of the installation location. Is partially shown.
[0035]
As described above, the configuration of the rotary cutter lock bit device with the pressure balance device according to the present invention has been described as an example, but the present invention is not limited to this configuration, and various changes can be made without departing from the scope of the claims. Needless to say,
[Brief description of the drawings]
FIG. 1 is a partial sectional perspective view of a rotary cutter lock bit device with a pressure balance device according to the present invention.
FIG. 2 is a vertical sectional view of a rotary cutter lock bit device with a pressure balancing device according to an embodiment of the present invention;
FIG. 3 is an enlarged sectional view of a circular portion showing a double seal structure of the apparatus of FIG. 2;
FIG. 4 is a partial cross-sectional view of a pressing portion of a rigid ring in the outer annular seal shown in FIG.
FIG. 5 is a perspective view of a main part of the outer annular seal of FIG. 2;
6A and 6B show a disc spring in a pressing portion of the rigid ring shown in FIG. 5, wherein FIG. 6A is a cross-sectional view and FIG. 6B is a perspective view thereof.
FIG. 7 is a cross-sectional view of the pressure balance device of the rotary cutter lock bit device according to the embodiment of the present invention, taken along line VII-VII of FIG. 2;
[Explanation of symbols]
Reference Signs List 10 rotary cutter lock bit device 20 bearing shaft 22 cutter 30 inner annular seal 32 outer annular seal 34 space 40 passage 42 pressure balance device 44 cylinder 46 rubber ball 50 inner diameter fitting portion 52 metal spring (corrugated disc spring)
54 Back-up rubber 56 Pressurizing part 60 Rigid ring 62 Radial surface 64 Radial surface 68 Shears tail back 70 Sliding bearing

Claims (4)

A plurality of bearing shafts, a cutter rotatably mounted on the bearing shaft, and an annular seal for shielding between the bearing shaft and the cutter from the outside, and an internal pressure between the bearing shaft and the cutter. In a rotary cutter lock bit device equipped with a pressure balance device for balancing the pressure and the external pressure,
The annular seal includes a rubber inner annular seal and an outer annular seal,
A rotary cutter lock bit device with a pressure balance device, wherein the outer annular seal is formed of a rigid metal ring, and the rigid ring performs metal sealing on the rotary cutter. 2. The rotary cutter lock bit device with a pressure balance device according to claim 1, wherein a pressure is applied by an elastic material to obtain a contact pressure of the metal seal in the outer annular seal. The rotary cutter lock bit device with a pressure balance device according to claim 2, wherein the rigid ring is pressed by a combination of pressing by a rubber material and pressing by a metal spring. The rotary cutter lock bit device with a pressure balance device according to claim 3, wherein the rubber material is a fluorine rubber material or a nitrile rubber material, and the metal spring is formed of a disc spring or a corrugated disc spring.

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