Fully sintered layer steel tooth roller bit and manufacturing method

Abstract

The invention relates to the technical field of roller bits, in particular to a full-sintered-layer steel-tooth roller bit and a manufacturing method, the full-sintered-layer steel-tooth roller bit comprises a plurality of palm and cone single pieces, each palm and cone single piece is composed of at least one palm and a cone connected with the palm through a bearing system, and the multiple palm and cone single pieces are welded to form a bit body; the cone comprises a central steel base body and a plurality of cone teeth, the full-sintered wear-resistant layer is integrally sintered and formed through a powder metallurgy process and wraps the outer part of the central steel base body, and the main component of the full-sintered wear-resistant layer is tungsten carbide; and the tooth metal frameworks are pre-buried in the fully-sintered wear-resistant layer and distributed in the circumferential direction of the roller cone. Through the high-proportion tungsten carbide wear-resistant layer which is integrally sintered and molded and the pre-embedded tooth metal framework, the tooth part of the tooth and the body form a compact and high-hardness composite structure at a time, and the tooth-embedded composite tooth drill bit has the double advantages of high structural integrity of a steel tooth drill bit and high wear resistance of a tooth-embedded drill bit; and the problems that the surfacing layer is easy to wear and peel off and the inserted teeth are easy to loosen are effectively avoided.

Description

Technical Field

[0001] This invention relates to the field of roller cone drill bit technology, specifically to a fully sintered steel tooth roller cone drill bit and its manufacturing method. Background Technology

[0002] Roller cone drill bits are key rock-breaking tools in the drilling and extraction of resources such as oil, mining, and geothermal energy. Connected to drill pipes or screw drills, they rotate under the drive of a top drive or hydraulic motor, using the roller cones to crush and cut the rock, thus achieving continuous drilling. Due to the harsh working environment, the wear resistance of the roller cone body and its teeth directly determines the service life and drilling efficiency of the drill bit.

[0003] Currently, the mainstream roller cone drill bits on the market are mainly divided into two categories: Steel-tooth roller cone drill bits: These drill bits are manufactured by directly milling the tooth structure onto a steel roller cone body, and then depositing a layer of wear-resistant material (such as tungsten carbide composite material) onto the tooth surface to enhance its wear resistance. The advantage of this method is its strong overall structural integrity. However, the tooth structure is essentially still made of steel, the thickness of the weld overlay is limited, and the bonding strength between the weld overlay and the base material is greatly affected by the manufacturing process. Under prolonged high-stress and high-wear conditions, the weld overlay is prone to wear and peeling, leading to rapid failure of the base tooth. Therefore, there is still significant room for improvement in overall wear resistance and service life.

[0004] Insert-tooth roller cone drills: These drills use independent, pre-sintered carbide teeth (usually made of tungsten carbide) that are pressed into the tooth holes of a steel roller cone body via an interference fit. Insert-tooth drills have extremely high tooth hardness and wear resistance. However, their disadvantages include the difference in thermal expansion coefficients between the carbide teeth and the steel roller cone body. Under drastic temperature changes and impact loads, the interface may loosen, leading to the risk of the carbide teeth falling off. Additionally, the machining precision requirements for the tooth holes are high, and the process is complex. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a fully sintered steel tooth roller cone drill bit and its manufacturing method.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a fully sintered steel tooth roller cone drill bit, comprising a single piece of tooth cone consisting of at least one tooth and roller cones connected thereto via a bearing system, wherein multiple single pieces of tooth cone are welded together to form the drill bit body; the roller cones include: A central steel base; A fully sintered wear-resistant layer integrally sintered by powder metallurgy and coated on the outside of the central steel substrate, wherein the main component of the fully sintered wear-resistant layer is tungsten carbide; In addition, a plurality of tooth metal skeletons are embedded in the fully sintered wear-resistant layer and distributed along the circumference of the toothed eaves.

[0007] Preferably, the surface of the toothed metal skeleton is provided with a local protrusion structure, and the protrusion structure is conical.

[0008] Preferably, the toothed metal skeleton is made of alloy steel.

[0009] Preferably, the alloy steel is 42CrMo.

[0010] Preferably, the fully sintered wear-resistant layer is formed by sintering a mixture of tungsten carbide powder and metal binder powder.

[0011] Preferably, the metal binder powder is one or more alloy powders selected from cobalt powder, nickel powder, and copper powder.

[0012] A method for manufacturing the roller cone of the fully sintered steel tooth roller cone drill bit includes the following steps: S1: Investment casting mold shell for making roller cones: S1.1: Create a wax model of the toothed wheel according to the preset shrinkage rate; S1.2: The wax mold is repeatedly dipped in ceramic refractory slurry and sprinkled with sand to form a refractory layer of a certain thickness; S1.3: High-temperature baking melts the wax mold and causes it to flow out, resulting in a hollow ceramic mold shell; S2: Prepare sintering powder: Mix tungsten carbide powder of different particle sizes with metal binder powder in a predetermined ratio to form a mixed powder; S3: Assembly and Loading: S3.1: Install multiple toothed metal skeletons into the corresponding toothed grooves on the inner wall of the ceramic mold shell; S3.2: The mixed powder is loaded into a ceramic mold shell with the toothed metal skeleton installed; S3.3: Place the central steel substrate into the mixed powder inside the ceramic mold shell; S3.4: Vibration-compacted mixed powder; S4: Sintering: The assembled mold shell is placed in a sintering furnace for sintering, so that the mixed powder is sintered and solidified, and forms a metallurgical bond with the tooth metal skeleton and the central steel matrix, thereby obtaining a toothed wheel with a fully sintered wear-resistant layer. S5: Post-processing: Remove the ceramic mold shell to obtain the sintered roller cone blank, and obtain the final roller cone product after subsequent processing.

[0013] Preferably, in step S4, the sintering is pressure sintering.

[0014] Preferably, the pressure sintering is hot isostatic pressing, in which pressure is applied to the pressure transmission medium through the pistons of the upper and lower hydraulic cylinders during the sintering process, and the sintering cavity is heated by an induction coil or resistor.

[0015] Preferably, the preparation of the mixed powder in step S2 is as follows: 75% of 200-400 mesh cast tungsten carbide, 15% of 80-200 mesh cast tungsten carbide and 10% of 40-60 mesh cast tungsten carbide are mixed to form a tungsten carbide mixed powder, and then the tungsten carbide mixed powder is mixed with Cu-Ni-Mn alloy powder in a ratio of 7:3.

[0016] The beneficial effects of this invention are as follows: This invention uses a high-proportion tungsten carbide wear-resistant layer integrally sintered and pre-embedded tooth metal skeleton to form a dense and high-hardness composite structure between the roller tooth and the body in one step. It combines the advantages of the strong overall structure of steel tooth drill bits and the high wear resistance of insert tooth drill bits, effectively avoiding the problems of easy wear and peeling of the weld overlay and easy loosening of insert teeth. It significantly improves the overall wear resistance and service life of the drill bit under harsh working conditions, thereby improving drilling efficiency. Attached Figure Description

[0017] Figure 1 This is a schematic diagram comparing the structures of existing steel-tooth roller cone drill bits and insert-tooth roller cone drill bits as described in the background art. Figure 2 This is a partial structural diagram of the steel toothed roller described in the background art; Figure 3 This is a schematic diagram of the single-piece structure of the toothed roller and toothed roller after being assembled by a bearing system according to the present invention. Figure 4 This is a schematic diagram of the toothed wax model and its cross-section produced in an embodiment of the present invention.

[0018] Figure 5 This is a schematic diagram of the process of dipping a wax mold in refractory slurry and sprinkling sand to form a shell in an embodiment of the present invention; Figure 6 This is a schematic diagram of the hollow ceramic mold shell obtained after dewaxing and curing in an embodiment of the present invention; Figure 7 This is a schematic diagram of the structure and installation positioning of the toothed metal skeleton pre-embedded in the sintered layer in an embodiment of the present invention. Figure 8 This is a schematic cross-sectional view of the assembly of the tooth metal skeleton, mixed powder and central steel substrate into the ceramic mold shell in an embodiment of the present invention. Figure 9 This is a schematic diagram of the hot isostatic pressing pressure sintering device used in an embodiment of the present invention; Figure 10This is a schematic diagram of the finished fully sintered roller cone after sintering and removing the ceramic mold shell in an embodiment of the present invention. Explanation of the labels in the diagram: 1: Toothed cone; 2: Toothed palm; 3: Bearing system; 4: Oil storage system; 5: Ceramic mold shell; 6: Toothed metal skeleton; 7: Central steel matrix; 8: Mixed powder; 9, 10: Sintering cavity; 11: Upper hydraulic cylinder piston; 12: Lower hydraulic cylinder piston; 13: Pressure transmission medium; 14: Induction coil. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0020] This invention provides a specific embodiment of a fully sintered steel tooth roller cone drill bit. The drill bit mainly consists of three toothed cone pieces welded together. Each toothed cone piece includes a toothed portion 2 and a cone 1 connected to it via a bearing system 3 and an oil reservoir system 4. The core of this embodiment lies in the manufacturing process of the cone 1.

[0021] The manufacturing steps of roller cone 1 are as follows: To create an investment casting mold shell, i.e., a ceramic mold shell: Wax model preparation: First, based on the final dimensions of the roller cone product and considering an estimated linear shrinkage of approximately 0.3% to 0.5% during sintering, a wax model of the roller cone is created by machining or combining molds, such as wooden or ceramic molds, and then injecting wax. (See...) Figure 4 The selected wax material can be low-temperature natural wax, microcrystalline wax, or industrial paraffin wax.

[0022] Shell Construction: The prepared wax model is repeatedly dipped into commercially available ceramic refractory slurries, such as alumina, zirconium oxide, vanadium oxide, or mortar series. After each dip, fine sand is sprinkled on and the mixture is dried. This process is repeated 5 to 6 times until a refractory mortar layer of sufficient strength with a thickness of approximately 0.5 mm to 2 mm is formed. See [link to relevant documentation]. Figure 5 .

[0023] Dewaxing and Curing: The wax mold coated with the thick refractory slurry is placed in a baking oven and baked at high temperature according to the characteristics of the refractory slurry. During this process, the inner wax mold melts and completely flows out, resulting in a hollow, cured ceramic mold shell 5, see [link to relevant documentation]. Figure 6 .

[0024] Preparation of sintering powder and framework: Powder Formulation: A mixed powder 8 is prepared to form the fully sintered wear-resistant layer. A specific formulation example is as follows: First, 75% of 200-400 mesh cast tungsten carbide, 15% of 80-200 mesh cast tungsten carbide, and 10% of 40-60 mesh cast tungsten carbide are mixed to form a tungsten carbide mixed powder. Then, this tungsten carbide mixed powder is mixed with 100-280 mesh copper-nickel-manganese alloy powder at a weight ratio of 7:3. The high proportion of tungsten carbide in this mixed powder ensures the extremely high wear resistance of the sintered layer.

[0025] Skeleton Preparation: The toothed metal skeleton 6 is fabricated using alloy steel, such as 42CrMo steel. The skeleton surface is designed with locally tapered protrusions to facilitate rapid and precise positioning within the tooth grooves of the ceramic mold shell 5. (See...) Figure 7 .

[0026] Mold assembly and loading: The processed metal skeletons 6 are installed one by one into the corresponding positions on the inner wall of the hollow ceramic mold shell 5.

[0027] Subsequently, the uniformly mixed sintered powder 8 is filled into the mold shell with the skeleton already installed.

[0028] Next, the pre-processed central steel substrate 7 is placed into the powder in the center of the mold shell.

[0029] Finally, place the entire assembly on a vibration table to compact the mixed powder inside, ensuring a dense filling. Figure 8 .

[0030] Sintering and shaping: After vibration, the assembled mold shell is fixed with support fixtures and then placed in a sintering furnace for sintering. Sintering can be carried out under vacuum or a protective atmosphere.

[0031] To achieve higher density and strength, this embodiment preferably employs hot isostatic pressing (HIP). For example... Figure 9 As shown, the assembled mold shell is placed in sintering chambers 9 and 10, surrounded by graphite powder as the pressure transmission medium 13. The central steel substrate 7 and the internal powder are induction heated by an induction coil 14, while pressure is applied to the pressure transmission medium 13 via the upper hydraulic cylinder piston 11 and the lower hydraulic cylinder piston 12, achieving a sintering process of simultaneous heating and pressurization. The sintering temperature must reach above the temperature required to melt the metal binder, and the pressure is set according to the equipment capacity and product requirements.

[0032] Post-processing: After sintering, allow the cavity to cool down and remove the workpiece. Mechanically break the outer ceramic mold shell 5 to obtain the roller cone blank with a dense, fully sintered wear-resistant layer formed inside. (See...) Figure 10 .

[0033] The roller cone blank is then subjected to necessary subsequent machining and cleaning.

[0034] Finally, the fully sintered wear-resistant toothed roller cone 1 and toothed plate 2, prepared according to the above method, are assembled and sealed through a bearing system 3 to form a single toothed roller cone piece. Three such single pieces are welded together according to existing technology to produce the fully sintered wear-resistant steel toothed roller cone drill bit of the present invention.

[0035] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A fully sintered steel tooth roller cone drill bit, comprising a single piece of tooth cone (1) consisting of at least one toothed tooth (2) and a roller cone (1) connected thereto via a bearing system (3), wherein multiple said toothed tooth cone single pieces are welded to form a drill bit body; characterized in that, The roller (1) includes: A central steel substrate (7); A fully sintered wear-resistant layer is integrally sintered by powder metallurgy and covers the outside of the central steel substrate (7). The main component of the fully sintered wear-resistant layer is tungsten carbide. In addition, a plurality of tooth metal skeletons (6) are embedded in the fully sintered wear-resistant layer and distributed along the circumference of the toothed eaves.

2. The fully sintered steel tooth roller cone drill bit according to claim 1, characterized in that, The surface of the toothed metal skeleton (6) is provided with a local protrusion structure, which is conical.

3. The fully sintered steel tooth roller cone drill bit according to claim 1 or 2, characterized in that, The toothed metal skeleton (6) is made of alloy steel.

4. The fully sintered steel tooth roller cone drill bit according to claim 3, characterized in that, The alloy steel is 42CrMo.

5. The fully sintered steel tooth roller cone drill bit according to claim 1, characterized in that, The fully sintered wear-resistant layer is formed by sintering a mixture of tungsten carbide powder and metal binder powder.

6. The fully sintered steel tooth roller cone drill bit according to claim 5, characterized in that, The metal binder powder is one or more alloy powders selected from cobalt powder, nickel powder, and copper powder.

7. A method for manufacturing the roller cone of a fully sintered steel tooth roller cone drill bit as described in any one of claims 1-6, characterized in that, Includes the following steps: S1: Investment casting mold shell for making roller cones: S1.1: Create a wax model of the toothed wheel according to the preset shrinkage rate; S1.2: The wax mold is repeatedly dipped in ceramic refractory slurry and sprinkled with sand to form a refractory layer of a certain thickness; S1.3: High-temperature baking causes the wax mold to melt and flow out, resulting in a hollow ceramic mold shell (5); S2: Prepare sintering powder: Mix tungsten carbide powder of different particle sizes with metal binder powder in a predetermined ratio to form mixed powder (8). S3: Assembly and Loading: S3.1: Install multiple toothed metal skeletons (6) into the corresponding toothed grooves on the inner wall of the ceramic mold shell (5); S3.2: The mixed powder (8) is loaded into the ceramic mold shell (5) with the toothed metal skeleton (6) installed; S3.3: Place the central steel substrate (7) into the mixed powder (8) inside the ceramic mold shell (5); S3.4: Vibration-compacted mixed powder (8); S4: Sintering: The assembled mold shell is placed in a sintering furnace for sintering, so that the mixed powder (8) is sintered and solidified, and forms a metallurgical bond with the tooth metal skeleton (6) and the central steel matrix (7), thereby obtaining a toothed wheel (1) with a fully sintered wear-resistant layer. S5: Post-processing: Remove the ceramic mold shell (5) to obtain the sintered roller blank, and obtain the final roller product after subsequent processing.

8. The manufacturing method according to claim 7, characterized in that, In step S4, the sintering is pressure sintering.

9. The manufacturing method according to claim 8, characterized in that, The pressure sintering is hot isostatic pressing. During the sintering process, pressure is applied to the pressure transmission medium (13) through the upper hydraulic cylinder piston (11) and the lower hydraulic cylinder piston (12), and the sintering cavity (9, 10) is heated through the induction coil (14) or resistor.

10. The manufacturing method according to claim 7, characterized in that, The preparation of the mixed powder (8) in step S2 is as follows: 75% of 200-400 mesh cast tungsten carbide, 15% of 80-200 mesh cast tungsten carbide and 10% of 40-60 mesh cast tungsten carbide are mixed to form tungsten carbide mixed powder, and then the tungsten carbide mixed powder is mixed with Cu-Ni-Mn alloy powder in a ratio of 7:3.

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