CN114135232A

CN114135232A - Bearing insert sleeve of roller bit and preparation method thereof

Info

Publication number: CN114135232A
Application number: CN202111449539.1A
Authority: CN
Inventors: 叶中郎; 徐磊; 王晋春; 张烈华; 沙成斌; 许林; 姜益; 江诗贵; 张勇
Original assignee: Kingdream PLC; Sinopec Oilfield Equipment Corp
Current assignee: Sinopec Oilfield Equipment Corp
Priority date: 2021-11-30
Filing date: 2021-11-30
Publication date: 2022-03-04
Anticipated expiration: 2041-11-30

Abstract

The invention relates to a bearing insert sleeve of a roller bit and a preparation method thereof, wherein the bearing insert sleeve of the roller bit comprises an insert sleeve body and a silver coating plated on the inner wall of the insert sleeve body; the bushing body is made of hard alloy, the hard phase of the bushing body is tungsten carbide, the bonding phase is cobalt, and the bonding phase accounts for 20-25 wt% of the hard alloy. The bearing insert sleeve of the roller bit has excellent wear resistance, excellent antifriction lubrication and heat conduction performance and good impact resistance, and can be suitable for high-bearing and high-impact use environments, such as petroleum drill bits and mining machinery.

Description

Bearing insert sleeve of roller bit and preparation method thereof

Technical Field

The invention relates to the technical field of petroleum and mine drilling, in particular to a bearing insert sleeve of a roller bit and a preparation method thereof.

Background

At present, a roller bit is a main tool for petroleum and mining, a cutting structure of the roller bit consists of a roller and a bit leg, the roller and the bit leg are locked and connected through an integrated bearing, and in the process of drilling a stratum, the roller rotates around a bit leg shaft neck along with the rotation of the bit, so that an external cutting tooth of the roller is driven to cut the stratum. Meanwhile, the roller bit bearing bears a huge load of 5-15T in the drilling process, and the roller bit bearing also bears a large impact force at the moment when the drill bit is in contact with the stratum, so that the drill bit bearing needs to have good wear resistance and impact resistance.

In the related art, the drill bit generally adopts an integrated bearing, that is, the bearing and the drill bit are integrated and made of the same material. The integrated bearing has limited performance due to the limitation of the material and process of the drill bit, usually a hardened layer is formed on the inner wall of the bearing in a carburizing and quenching mode, the thickness of the hardened layer is small, the hardness of the core part of the bearing is low, and when the load is high or the drill encounters the condition of a hard stratum, the hardened layer is rapidly worn, so that the working surface of the bearing is excessively worn, and the drill bit fails in advance.

In another related technology, the drill bit adopts a bushing bearing, namely a steel bushing is embedded in a shaft hole of the drill bit, so that the steel bushing can be processed and thermally treated more optimally, the wear resistance of the steel bushing can be improved to a certain extent, the steel bushing has good overall hardness, strength and surface processing quality, and the overall performance of the bearing is further improved. However, the steel bushing has limited hardness and wear resistance, wherein the hardness is usually 54-56 HRC, and the steel bushing still has wear failure under a heavy load condition.

The hard alloy material has excellent hardness and wear resistance, and is an ideal material for machining cutters and drill cutting teeth. However, for the drill bearing, the impact performance of the existing hard alloy is obviously lower than that of steel, and the existing hard alloy cannot be suitable for drilling conditions. The drill bearing usually adopts the way of plating silver with an electric brush to achieve the function of reducing the abrasion, and the hard alloy material has lower metal content, which is equivalent to the metal material with higher difficulty of plating the electric brush. In addition, the drill bushing bearing is assembled by heating the shaft hole, cooling the bushing and then embedding the bushing in the shaft hole, but the conventional hard alloy has a much lower expansion coefficient than a metal material, which results in insufficient fastening force of the bushing.

Disclosure of Invention

In order to solve the technical problems, the invention provides a high-cobalt hard alloy bearing and a proper silver plating process, and achieves the purposes of wear reduction and impact resistance while maintaining the excellent wear resistance of hard alloy.

The technical scheme provided by the invention is as follows:

in a first aspect, a roller bit bearing insert sleeve is provided, which comprises an insert sleeve body and a silver coating layer arranged on the inner wall of the insert sleeve body; the bushing body is made of hard alloy, the hard phase of the bushing body is tungsten carbide, the bonding phase is cobalt, and the bonding phase accounts for 20-25 wt% of the hard alloy.

The hardness of the bearing insert sleeve of the roller bit is HRA 81-85, and the impact toughness is 10-13J/cm²Not only can bear higher load and has good impact property, but also has higher linear expansion coefficient of 8 multiplied by 10^-6～10×10^-6The temperature per DEG C and the antifriction performance, after the shaft hole is heated, the embedded sleeve is cooled, and the embedded sleeve is embedded in the shaft hole for assembly, the fastening force of the embedded sleeve is not influenced, and the abrasion to the shaft neck of the bit leg is small due to the silver coating.

In some embodiments, the silver coating has a thickness of 25 to 100 μm; the thickness of the silver coating is 50-100 μm.

Under the condition of specific cobalt content, the bearing hardness is controlled by adjusting the average particle size of a hard phase, and in some embodiments, the average particle size of tungsten carbide is 3-6 μm; the hardness of the tungsten carbide is 1600-1800 Hv. Preferably, the tungsten carbide has an average particle size of 4 μm and a hardness of 1700 Hv.

In some embodiments, the bearing insert sleeve of the roller bit comprises an insert sleeve body, a nickel plating layer, a silver priming layer and a silver plating layer from outside to inside in sequence, wherein the thickness of the nickel plating layer is 5-10 mu m, and the thickness of the silver priming layer is 5-10 mu m.

In a second aspect, a method for preparing the bearing insert of the roller cone bit is provided, which comprises the following steps:

preparing the bushing body by a hot isostatic pressing technology;

cleaning and blackening the inner wall of the bushing body;

and electroplating a silver layer on the inner wall of the cleaned and blackened bushing body by an electric brush plating method.

In some embodiments, the conditions for preparing the insert body by hot isostatic pressing are: the pressure is 6-6.2 MPa, the temperature is 1450-1470 ℃, and the pressing time is more than 50 min.

The process of electroplating a silver layer on the inner wall of the treated insert sleeve body by an electric brush plating method comprises:

pre-nickel plating: forming a nickel plating layer for transition on the insert sleeve body 1 by using a nickel flash plating solution; silver plating: electroplating silver priming layer on the nickel plating layer by using silver-indium flash plating solution;

silver plating: and (4) performing electric brush silver plating on the silver priming layer by utilizing silver-indium plating solution to form a silver plating layer.

The technical scheme provided by the invention has the beneficial effects that:

according to the bearing insert sleeve of the roller bit, the insert sleeve body is made of the hard alloy with high cobalt content, so that the insert sleeve has high wear resistance and high impact resistance, and the bearing insert sleeve of the roller bit has a high linear expansion coefficient of 8 multiplied by 10^-6～10×10^-6The temperature per DEG C is more favorable for the assembly of the bushing, ensures the fastening force and also more favorable for electroplating a silver coating on the surface of the bushing to play a role in reducing the abrasion of the shaft neck of the bit leg.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a schematic view of a bearing for a roller cone drill bit provided by an embodiment of the present invention;

FIG. 2 is a schematic cross-sectional view of a bearing insert for a roller cone drill bit according to an embodiment of the present invention;

FIG. 3 is an electron microscope image of a hard alloy used for a bearing insert of a roller cone drill bit according to an embodiment of the present invention;

in the figure: 1. the bushing body; 2. a silver coating layer; 3. a cone; 4. a bit leg journal; 5. cutting teeth; 6. a locking structure; 7. a bearing sealing structure 8, a hard phase; 9. and (4) a bonding phase.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

Referring to fig. 1, the bearing insert of the roller bit according to the embodiment of the present invention is fixed in the axial hole of the roller cone 3 in an embedded manner, and is fixed with the bit leg journal 4 by the locking structure 6 to form a bearing pair. At the moment when a drill bit contacts with a stratum, the bearing insert sleeve 1 of the roller cone bit bears huge impact force, the bearing insert sleeve 1 of the roller cone bit bears huge load in the drilling process, and the inner wall of the bearing insert sleeve 1 of the roller cone bit and a bit leg shaft neck 4 rub against each other in the rotating process of a roller cone 3 and a cutting tooth 5, so that the bearing insert sleeve of the roller cone bit needs to have two performances of good wear resistance and small damage to a coupling part.

Referring to fig. 2, the bearing insert for the roller cone drill bit according to the embodiment of the present invention includes an insert body 1 and a silver plating layer 2 disposed on an inner wall of the insert body 1. For wear resistance, on one hand, the basic wear resistance of the bushing body 1 is ensured by adopting a material with high hardness; on the other hand, the silver coating 2 is arranged on the inner wall of the bushing to achieve the purposes of reducing abrasion, lubricating and radiating, and the means can also improve the wear resistance of the bearing. Preferably, the insert body 1 is made of a cemented carbide with a high cobalt content, the hard phase 8 of which is tungsten carbide and the bonding phase 9 of which is cobalt, wherein the bonding phase 9 accounts for 20 wt% -25 wt% of the cemented carbide. By adopting the technical scheme, the bushing body 1 has good wear-resisting and supporting effects, the silver-plated layer 2 on the surface of the inner wall of the bushing body can play good roles in reducing wear, lubricating and radiating, the impact resistance of the bearing bushing of the roller bit can be obviously improved, and the impact toughness is 10-13J/cm²And the bearing insert sleeve of the roller bit is ensured not to be broken in the using process.

In order to meet the use requirements of different wear resistances, the hardness of the insert sleeve body 1 is controlled by adjusting the average granularity of tungsten carbide, so that the bearing insert sleeve of the roller bit has excellent wear resistance and antifriction and lubricating effects, and the problem is solvedIn the related technology, under the high-bearing and high-impact use environment, the surface of a bearing insert of the roller bit is rapidly abraded, and the bit fails in advance. Referring to fig. 3, in some alternative embodiments, under the condition that the content of the bonding phase 9 is specific, the hardness of the bushing body 1 is controlled by adjusting the average grain size of the hard phase 8, the hard phase 8 is made of tungsten carbide, the average grain size of the tungsten carbide is 3-6 μm, the hardness is 1600-1800 Hv, and finally the hardness of the bushing body 1 is HRA 81-85. Among them, the average particle size of the hard phase 8 is preferably 4 μm, and the hardness is preferably 1700 Hv. The bonding phase 9 of the invention adopts cobalt, and the content of the cobalt is controlled to be 20-25 wt% of the hard alloy, and 20 wt% is preferred. Taking a hard alloy with 10 wt% of cobalt as an example, no matter how to adjust the process parameters for silver coating, the binding force between the silver coating layer 2 and the insert body 1 can not meet the requirement of the ASTM B571 thermal shock test, and peeling can occur. Meanwhile, the expansion coefficient of the hard alloy with the cobalt content of 10 wt% (5 multiplied by 10)^-6～6×10^-6/° c) about 1/2 of carbon steel only, the expansion of the bearing bore of the roller cone bit is far larger than that of a 10% cobalt hard alloy insert at the downhole temperature of 200 ℃, and the bearing insert of the roller cone bit falls off from the shaft bore of the roller cone 3. The linear expansion coefficient of the hard alloy with 20-25 wt% of cobalt is 8 multiplied by 10^-6～10×10^-6The linear expansion coefficient of the bearing insert is close to that of the cone 3, and the bearing insert of the cone drill bit made of the bearing insert can be tightly embedded in the shaft hole of the cone 3, so that the bearing insert of the cone drill bit and the cone 3 cannot loosen and fall off in the process of rotating relative to the cone leg journal 4.

Referring to fig. 2, in some alternative embodiments, the thickness of the silver plating layer 2 on the inner wall surface of the insert body 1 is 25 to 100 μm, and the thickness of the silver plating layer 2 is preferably 50 μm. The silver coating 2 has good functions of antifriction, lubrication and heat dissipation, can effectively prolong the service life of the hard alloy bushing bearing, and reduces the risk of adhesive wear. The adhesion abrasion means that atoms of metals on two contact surfaces are adhered due to bonding action in the process of rotating the bearing, adhesion points are sheared, metal transfer occurs, and the bearing is abraded and fails. The thicker the silver coating 2 of the bearing insert sleeve of the roller bit provided by the invention is, the better the antifriction and lubricating effects are. Through a comparison test at the rotating speed of 300rpm and under the load of 50KN, the running time of the silver coating 2 with the thickness of 25 mu m on the insert sleeve body 1 is 110-120 h, and the running times of the silver coating 2 with the thicknesses of 50 mu m and 100 mu m are respectively and relatively improved by about 10% and 15%.

The technical solution of the present invention is explained in detail by the following specific examples.

Example 1

The positive and negative electrodes used in the following steps are graphite electrodes, and the brush plating rotation speed is 60 rpm.

(S1) preparing tungsten carbide powder with the average particle size of 3-6 mu m and the hardness of 1600-1800 Hv and pure cobalt powder with the particle size of less than or equal to 5 mu m, granulating together, adding into a die, sintering at 1460 ℃ for 60min by adopting a hot isostatic pressing technology and setting the sintering pressure to be 6MPa, and obtaining the insert sleeve body 1 with the working surface diameter of 50mm and the length of 20 mm.

(S2) pretreating the insert body 1 by an electrochemical method:

(S21) electric cleaning and oil removal: taking a sodium hydroxide solution with the concentration of 34.3g/L as an electric cleaning solution, setting the voltage to be + 8-10V, and setting the electric cleaning time to be 21-23 s;

(S22) removing scale and rust on the surface of the insert body 1 by acid pickling: using hydrochloric acid aqueous solution with the concentration of 20mL/L as pickling solution, setting the voltage to be-8-10V, and the pickling time to be 25-27 s;

(S23) removing carbon black generated in the acid washing process: the method comprises the steps of taking sodium hydroxide solution containing formaldehyde as black removing liquid, setting the voltage to be-14-16V, and setting the black removing time to be 34-36 s.

(S3) silver plating the inner wall of the insert body 1 by brush plating:

(S31) nickel preplating: a nickel flash plating solution is used for forming a nickel plating layer with the thickness of 5-10 mu m for transition on the insert sleeve body 1 so as to improve the bonding force between the silver plating layer 2 and the insert sleeve body 1. The nickel flash plating solution is a chelated nickel sulfate solution containing formate, and the nickel content is 110 g/L; the electroplating voltage is + 8-10V, and the electroplating time is 20-22 s;

(S32) pre-silver plating: electroplating a silver priming layer with the thickness of 5-10 mu m on the nickel plating layer by using a silver-indium flash plating solution to prepare for an electric brush silver plating process; the silver-indium flash plating solution is soluble indium solution containing potassium cyanide and silver, the silver content is 1.3g/L, the indium content is 20g/L, and the pH value is 9.0-10.0; the electroplating voltage is + 8-10V, and the electroplating time is 20-22 s;

(S33) silver plating: silver is plated on the silver priming layer by an electric brush by utilizing silver-indium plating solution; the silver-indium plating solution is soluble indium solution containing potassium cyanide and silver, the silver content is 100-110 g/L, the indium content is 50g/L, and the pH value is 9.0-10.0; the electroplating voltage is + 3.5-3.7V, the duty ratio is 50-55%, and the pulse frequency is 500 Hz.

TABLE 1 Brush plating Process and Electrical parameters of example 1

Example 2

Referring to FIG. 1, firstly, heating a cone 3 to 200-250 ℃, and preserving heat for 20min to expand and expand a bearing pin hole; meanwhile, liquid nitrogen is adopted to cool the bearing insert sleeve of the roller bit for 10-20 s, and then the cooled bearing insert sleeve of the roller bit is embedded in the shaft hole of the roller 3 and is installed on the bit leg shaft neck 4 together to form a bit bearing pair. The surface of the bit leg shaft neck 4 can be subjected to surfacing alloy reinforcement, so that the wear resistance of the bit leg shaft neck is improved.

Testing the assembled product:

(1) testing the maximum bearing capacity of the bearing insert of the roller bit at the rotating speed of 300 rpm;

(2) testing the service life of the bearing insert of the roller bit at the rotating speed of 300rpm and the load of 50 KN: a limit torque is set on the bearing testing machine, if the bearing insert sleeve of the roller bit is obviously abraded, the torque will give an alarm, and at the moment, the bearing insert sleeve of the roller bit needs to be scrapped.

TABLE 2 test results of different roller bit bearing inserts

The 8' 1/2-sized drill bit product prepared by the scheme of the sample A has the bearing life of 158 hours in a field use test, and is not damaged;

the 12' 1/4 gauge drill bit product prepared using the protocol of sample B achieved 182 hours of bearing life in the field service test with no damage.

The foregoing are merely exemplary embodiments of the present invention, which enable those skilled in the art to understand or practice the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A bearing insert sleeve of a roller bit is characterized in that: comprises an inlay sleeve body and a silver coating arranged on the inner wall of the inlay sleeve body; the bushing body is made of hard alloy, the hard phase of the bushing body is tungsten carbide, the bonding phase is cobalt, and the bonding phase accounts for 20-25 wt% of the hard alloy.

2. The roller cone bit bearing insert of claim 1, wherein: the thickness of the silver coating is 25-100 μm.

3. The roller cone bit bearing insert of claim 1, wherein: the thickness of the silver coating is 50-100 mu m.

4. The roller cone bit bearing insert of claim 1, wherein: the average particle size of the tungsten carbide is 3-6 mu m.

5. The roller cone bit bearing insert of claim 1, wherein: the hardness of the tungsten carbide is 1600-1800 Hv.

6. The roller cone bit bearing insert of claim 1, wherein: the tungsten carbide has an average particle size of 4 μm and a hardness of 1700 Hv.

7. The roller cone bit bearing insert of claim 1, wherein: the bearing insert sleeve of the roller bit sequentially comprises an insert sleeve body, a nickel plating layer, a silver priming coat and a silver plating layer from outside to inside.

8. The roller cone bit bearing insert of claim 7, wherein: the thickness of the nickel-plated layer is 5-10 mu m, and the thickness of the silver base layer is 5-10 mu m.

9. A method for preparing the bearing insert of the roller cone bit of any one of claims 1 to 8, wherein the method comprises the following steps:

preparing the bushing body by a hot isostatic pressing technology;

pre-treating the inner wall of the bushing body;

and electroplating a silver layer on the inner wall of the treated insert sleeve body by an electric brush plating method.

10. The method of making a roller cone bit bearing insert according to claim 9, wherein: the electroplating of the silver layer on the inner wall of the treated insert sleeve body by the brush plating method comprises the following steps:

pre-nickel plating: forming a nickel plating layer for transition on the insert sleeve body 1 by using a nickel flash plating solution;

silver plating: electroplating silver priming layer on the nickel plating layer by using silver-indium flash plating solution;