RU2536901C2 - Diamond drill bit with mechanical attachment of cutters - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to drilling and can be used in production of diamond drill bits with steel bodies. Drill bit comprises body, flushing assemblies, PDC cutters arranged in bushes of plastic metal fitted in blade holes. PDC cutter is attached with the help of two conical lock bushes fitted one into another. One of the latter has outer cylindrical surface mating with blade hole wall and inner conical surface symmetrical about hole axis, its cone vertex facing its bottom. Another bush with inner cylindrical surface mating with PDC cutter bottom surface and outer conical surface symmetric with hole axis, cone vertex facing its inlet. PDC cutter mount hole bottom has through hole in blade of smaller diameter intended for mounting or withdrawing of PDC cutter by axial impacts or squeezing with the help of drift pin to allow worn-out section turn and replacement at cutting edge by turn through required angle relative to axis or complete replacement of PDC cutter with new one.

EFFECT: higher reliability, longer life, simplified repair.

8 dwg

Description

The invention relates to the field of drilling equipment, namely to diamond bits for drilling wells in the oil and gas industry.

A diamond bit is known [1], adopted as an analogue, in which the cutting elements are represented by crystals of natural diamonds, the edges of which provide direct destruction of the rock at the bottom. Natural or synthetic diamonds are placed in a sintered matrix, usually copper-carbide, which is integral with the lower part of the steel hollow body of the bit. Exposure and fixing of diamond cutting elements depends on the selection of matrix components in the manufacture of bits. With quick and large exposure, diamonds crack and crush, and with insufficient exposure, they almost do not penetrate the rock and drilling proceeds at a low mechanical speed. On the working matrix surface, gaps are made between the matrix and the rock for abundant wetting of diamonds and circulation channels for the washing fluid flowing from the internal cavity of the bit, in the form of grooves between the blades, sectors, etc.

Single-layer bits are obtained by single-layer laying of large diamonds in a graphite mold in a certain order on the matrix surface, and impregnated - uniformly mixed diamonds with tungsten carbide particles and other matrix components before sintering the bit. The thickness of the impregnated layer is from 6 to 10 mm. When the matrix is abraded, more and more crystals appear on its surface, providing cutting of the rock at the bottom.

The advantages of this type of diamond bits include high abrasion resistance of diamond crystals, and the disadvantages are the difficulty and low reliability of fixing in the matrix.

A diamond bit is known [2], adopted as another analogue, in which the cutting elements are made in the form of PDC cutters with a diamond plate mounted on top of a cylindrical carbide substrate. PDC cutters are installed in holes made on blades protruding above the surface of the body from the bottom side and from the side of the well wall. The purpose of the first is the destruction of the rock at the bottom, the second is to protect the diameter of the bit from abrasion. The diamond plate for PDC cutters is made from diamond powder with the addition of an iron group catalyst, usually cobalt. At temperatures of many hundreds of degrees and pressures of many hundreds of atmospheres, diamond powder turns into a conglomerate with unique properties - super resistance to overheating and abrasion. A diamond plate can be attached to the carbide substrate of the cutter in various ways, from welding during pressing to soldering with various types of solders.

Finished PDC cutters with fixed diamond plates are fixed to the body of the diamond bit using low-temperature solder with a melting point of less than 700 ° C. Depending on the type of diamond powder and the parameters of the technology for converting it into a conglomerate during sintering and pressure, the finished plates have three heat resistance thresholds: about 400 ° C, about 750 ° C and about 1250 ° C. Accordingly, at these temperatures, part of the diamond conglomerate cracks. Therefore, in the manufacture of plates for diamond drill bits, they try to tighten the technology and bring their heat resistance closer to 800 ° C and more.

Despite the fact that the temperature of the soldering of the cutters when installing them in the holes on the body of the bit should not exceed 700 ° C (melting of the solder), heating to this temperature during the manufacture of the bit, when the plates are heat resistant to 800 ° C, negatively affects the strength and heat resistance.

Another negative property of diamond bits is that when they are repaired, heating is carried out so that the solder allows to remove partially worn out bits during drilling from the nests in the bit. After checking the condition of wear on the part of the edge of the diamond plate, the cutter is deployed in the bit nest in such a way that the worn edge comes out and the idle edge comes into its place and it becomes possible to destroy the rock in the face with a new annular section of the working edge. Cutters with replaced sections of the cutting edge of the insert must be re-heated, for the third time, to 700 ° C to be fixed by soldering. This further negatively affects the further strength and heat resistance of the plate.

Another disadvantage of the prototype is the need to deliver bits hundreds of kilometers away for repair to a specialized workshop or to a bit factory, since there are no conditions directly at the drilling site for restoration of bits.

A known method of fastening rock-cutting inserts of a drilling tool [3], adopted as a prototype, in which in the working body of the drilling tool and tunneling machines the rock-cutting inserts are located in bushings made of ductile metal, which are pressed into the working body of the drilling tool, and on the outer surface of the bushings longitudinal grooves are made. The positive properties of this method are several factors. Pressing inserts into plastic bushings reduces compression stress and increases the actual contact surface. Under the action of bending stresses, i.e. compression and stretching, plastic inserts are deformed and the total stresses acting on the inserts are reduced. Fastening is carried out without heating and soldering.

The negative is that this method does not allow for a reversal and a new installation of the insert towards the breed with the worn side.

The aim of this invention is to create a reliable version of the diamond bit with mechanical fastening of the cutters, simple technologically and allowing assembly and repair without heating and soldering, adversely affecting the strength and heat resistance of PDC cutters.

The technical result of the present invention is to increase the reliability and durability of PDC diamond bits by eliminating soldering, as well as to simplify their repair, making it possible even in conditions directly on the drilling site.

This result is achieved in that in a diamond bit with mechanical fastening of the cutters containing a body with a connecting thread, flushing units for cleaning the bottom of the sludge, fixed PDC rock cutting tools located in ducts made of ductile metal in the holes on the blades, the PDC cutter is mounted using pairs of conical locking bushings inserted one into the other, one with the outer cylindrical surface, the mating wall of the hole in the blade, and the inner conical surface, symmetrical second hole axis, the apex of the cone facing towards the bottom thereof, and the other sleeve with an inner cylindrical surface of the counter surface PDC cutter base, and the outer conical surface symmetrical axis of the hole, the vertex of the cone faces in the direction of its inputs; in the bottom of the hole for the PDC cutter, there is a coaxial through hole in the blades, smaller in diameter, for introducing into it and removing from the hole the PDC cutter being repaired or replaced by axial impacts or by extrusion using a punch to ensure rotation of the worn section and replacing it on the working cutting edge with a turn at the desired angle relative to the axis or completely replace the PDC cutter with a new one.

The proposed diamond bit with mechanical fastening of the cutters allows to increase the durability and maintainability in the drilling environment.

The list and description of the figures of the drawings.

Figures 1 and 2 show a view of a diamond drill bit with PDC cutters and flushing units.

Figure 3 presents the attachment site of the PDC cutter in section AA of the blade passing through the axis of the cutter.

Figure 4 shows the layout of the holes in the blades, tools and fastening elements of the PDC cutter in the order of their assembly.

Figure 5 shows the final position of the attachment elements of the PDC cutter.

Figure 6 shows the position of the PDC cutter attachment elements with an option to partially remove the PDC cutter attachment elements covering its working surface, as well as a tool for punching or extruding a replaceable or repaired PDC cutter.

7 shows a variant of an embossed PDC cutter with an inner conical sleeve.

On Fig presents a variant of the shift of the inner sleeve from the surface of the cutter PDC using the bottom stop and mandrel.

In figure 1, the positions denote: 1 - a diamond bit with a steel body, 2 - rock cutting PDC cutters, 3 - PDC cutters protecting the bit diameter from abrasive wear, 4 - blades for fixing cutters 2 and 3; 5 - grooves for the passage of flushing fluid, 6 - grooves for screwing-unscrewing the bit when it is attached, 7 - tapered thread for attachment to the drill string.

In Fig. 2, the same positions denote the elements shown in Fig. 1, as well as 8 indicate the flushing units and the direction of the section AA passing through the plane of symmetry of one of the PDC cutters.

In figure 3, the positions indicated: 4 - the blade of the bit, 2 - the cutter PDC, 9 - the hole for the cutter 2 in the blade 4; 10 - outer conical sleeve, 11 - inner conical sleeve, 12 - hole for punching or extruding the PDC cutter.

In Fig. 4, the same positions in the assembly sequence indicate the elements shown in the previous figures, as well as 13 designates a mandrel for force acting on the inner conical sleeve 11 when fixing or replacing the cutters 2; 14 - the bottom of the hole 9. The arrow indicates the direction of the force when fixing the cutters 2.

Figure 5 shows the extreme position of the mandrel 13 when securing the cutters 2 with the same positions shown in the previous figures.

6, the position 15 denotes a tool - a mandrel for punching or extruding the cutters 2 from the hole 9.

7 shows the position in which the cutter 2 is already extruded from the outer conical sleeve 10 together with the inner conical sleeve 11.

On Fig shows how to remove the conical sleeve 11 from the cutter 2. Position 16 indicates the stop for the end face of the cutter 2.

Mounting rock cutting tools PDC in the prepared holes on the blades of the bit is as follows.

An outer conical sleeve 10 is inserted into the hole 9. Then, a PDC cutter 2 is inserted before contacting the bottom of the hole 14. On the cutter 2, an inner conical sleeve 11 is put on top, which is then pushed with a force into the gap between the outer cylindrical surface of the PDC cutter 2 and the conical sleeve 10. The angles of the cones on both bushings, the friction force during adhesion and the applied pressing or clutch force between the wall of the hole 9, the outer and inner surfaces of the conical bushings 10 and 11, as well as the wall of the PDC cutter 2 for various sizes of PDC teeth, are individually and individually selected in diameter and length to ensure 100% retention of PDC cutters ie the entire period prior to repair drilling. If it is necessary to rotate the worn part of the cutting edge relative to the axis of the PDC cutter or completely replace it with a new one using a punch or by pressing out with a tool 15 inserted through the hole 12, the PDC cutter 2 is removed from the socket, as shown in Fig. 7. If necessary, the inner sleeve 11 is removed by the mandrel 13 from the surface of the cutter 2 PDC.

With a new fastening of the PDC teeth, the tapered bushings 10 and 11 can be reused or replaced.

After turning the PDC cutter to the desired angle relative to the axis or after completely replacing the PDC cutter with a new one, it is installed in hole 9 in the above order.

The absence of triple heating of PDC cutters to 700 ° C, which is inevitable during soldering, can significantly increase the life of diamond bits.

Information sources

1. "A tool for drilling wells", I.K. Maslennikov, G.I. Matveev, - M., 1981, "Nedra", pp. 233-238 (analogue).

2. “Diamond bit”, “Line FD”, catalog of drill bits of OJSC “Volga-Burmash”, 2003, Samara, p. 36 (analogue).

3. RF patent No. 2477780 dated 03/20/2013, cl. Е21В 10/573, Е21С 35/197, “Method for fastening rock-cutting inserts of drilling tools and working bodies of tunneling machines” (prototype).

Claims (1)

A diamond bit with mechanical fastening of the cutters, comprising a body with a connecting thread, flushing units for cleaning the bottom of the sludge, fixed PDC rock cutting tools located in ducts made of plastic metal in the holes on the blades, characterized in that the PDC cutter is mounted using a pair inserted with by force of conical locking bushings one into the other - one with the outer cylindrical surface, the mating wall of the hole in the blade, and the internal conical surface symmetrical to the axis of the hole I, with the top of the cone facing its bottom, and another sleeve with an inner cylindrical surface, a mating surface of the base of the PDC cutter, and an outer conical surface that is symmetrical to the axis of the hole, the top of the cone facing its entrance; in the bottom of the hole for the PDC cutter, there is a coaxial through hole in the blades, smaller in diameter, for introducing into it and removing from the hole the PDC cutter being repaired or replaced by axial impacts or by extrusion using a punch to ensure rotation of the worn section and replacing it on the working cutting edge with a turn at the desired angle relative to the axis or completely replace the PDC cutter with a new one.

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