Core claw, manufacturing method and core drill bit

Abstract

The present application belongs to the technical field of drilling equipment, and provides a core claw, a preparation method and a core drill bit, wherein the core claw comprises a shell and an alloy claw body, the shell is cylindrical, a plurality of alloy claw bodies are fixed at one end of the inner surface of the shell in equal intervals along the circumference of the shell, the cross section of the alloy claw body along the radial direction of the shell is a right-angled triangle, and a continuous triangular stepped surface is arranged on the cross section along the radial direction, the continuous triangular stepped surface serves as a wear-resistant layer and faces the axis of the shell.In the core claw of the present application, the surface of the alloy claw body serves as a wear-resistant layer, and there is no need to additionally process a wear-resistant layer, thereby omitting the step of installing a wear-resistant layer, simplifying the manufacturing process, and avoiding the problem of the wear-resistant layer falling off.

Description

Technical Field

[0001] This invention belongs to the field of drilling equipment technology, and specifically relates to a core claw, its preparation method, and a core drill bit. Background Technology

[0002] Core sampling is a crucial operation in oil and gas resource exploration and development for discovering oil and gas reservoirs and determining basic data about the oil and gas layers. Its main steps involve the drill bit drilling to form a core. After the core enters the core sampling chamber, the core catches are loaded, enclose, and clamp the core, further breaking it off or twisting it. During the subsequent hoisting of the drill string, the core catches hold the core firmly to prevent it from slipping. Therefore, the performance of the core catches directly affects the success of the core sampling operation.

[0003] In the current manufacturing method, the core claw body and the shell are integrally formed on the same plate using machining methods, with no connecting interface between the two. Subsequently, cemented carbide particles and solder are applied to the surface of the claw body, and the cemented carbide wear-resistant layer is connected to the surface of the claw body by welding. Its structure is as follows: Figure 1 As shown, the claw body (marked I) is made of 40Cr or 42CrMo material, the wear-resistant layer (marked III) is made of WC cemented carbide material, and the two are bonded together by a welding layer (marked II).

[0004] During service, the wear-resistant layer on the surface of the core claw is in direct contact with the core. When the drill string is lifted, the wear-resistant layer increases friction and grips the core tightly. However, the cemented carbide particles and the claw body are welded together from dissimilar materials, resulting in low connection strength and a weak interface. When the drill string is lifted, the welded wear-resistant layer may peel off, leading to insufficient core claw capacity, core slippage, and ultimately, core extraction failure. Summary of the Invention

[0005] To address the problems in the background art, this invention proposes a core claw, a preparation method, and a core drill bit.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A core claw, the core claw comprising a shell and an alloy claw body;

[0008] The shell is cylindrical, and the alloy claw is installed at one end of the inner surface.

[0009] Several sets of the alloy claws are fixed at equal intervals along the circumference of the housing to the inner surface of the housing;

[0010] The cross-section of the alloy claw along the radial direction of the shell is a right-angled triangle, and the radial cross-section is provided with continuous triangular stepped surfaces;

[0011] The continuous triangular stepped surface serves as a wear-resistant layer, facing the axis of the shell.

[0012] Furthermore, the alloy claw body is provided in 8 groups, with 1 claw in each group.

[0013] Furthermore, the housing is made of 40Cr or 42CrMo sheet, and the alloy claw is made of Fe-B alloy.

[0014] A method for preparing a core claw, comprising the following steps:

[0015] The alloy raw materials are melted, heated to 1600±20℃, deoxidizer is added, and the temperature is held for 3-5 minutes. Then the furnace is taken out at 1600~1620℃, and the raw material ingots of the alloy claw body are cast using sand casting. After air cooling to room temperature, several combined gold claw bodies are obtained.

[0016] Select 40Cr or 42CrMo plates with a thickness of 1-2mm;

[0017] The alloy claw body is welded onto the plate.

[0018] The plate material after welding the alloy claw is processed into a cylindrical shell, so that the alloy claw is located on the inner surface of the shell.

[0019] Furthermore, the alloy raw materials include ferroborone, ferrochrome, and ferromolybdenum.

[0020] Furthermore, in the alloy claw body:

[0021] The content of B is 2wt%-3wt%, the content of Cr is 6wt%-8wt%, the content of Mo is 4wt%-6wt%, and the remainder is Fe.

[0022] Furthermore, the deoxidizer is pure aluminum.

[0023] Furthermore, the width of the alloy claw body is 5-8mm, and the height of the highest triangular step surface is 8-10mm.

[0024] Furthermore, when welding the alloy claw body onto the plate, manual arc welding is used, and the welding wire is an Fe-based flux-cored welding wire.

[0025] A core drill bit, equipped with the aforementioned core claw.

[0026] The beneficial effects of this invention are:

[0027] 1. In the core claw of the present invention, the surface of the alloy claw body serves as a wear-resistant layer, eliminating the need for additional processing of the wear-resistant layer, thus simplifying the manufacturing process. The alloy claw body itself serves as the wear-resistant layer, making it less prone to wear and more durable, and avoiding the problem of the wear-resistant layer falling off.

[0028] 2. In the preparation process of the core claw of the present invention, Fe-B alloy is used to prepare the alloy claw body, and then the surface facing the shell axis is used as a wear-resistant layer to improve the wear resistance. At the same time, the shell is made of 1-2mm plate, which does not require machining, further simplifying the process.

[0029] 3. The quality inspection method of the core claw of the present invention can improve the matching degree between the rock sample and the inner diameter of the shell, ensure the accuracy of the experiment, and at the same time, through comparative experiments, the performance difference between the existing core claw and the improved core claw can be evaluated.

[0030] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 A schematic diagram of the structure of a conventional core claw is shown.

[0033] Figure 2 A schematic diagram of the structure of a core claw according to the present invention is shown;

[0034] Figure 3 A schematic diagram of the alloy claw body of the present invention is shown.

[0035] In the diagram: 1. Shell; 2. Alloy claw. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] A type of core claw, such as Figure 2As shown, the core claw includes a shell 1 and an alloy claw body 2, wherein the shell 1 is cylindrical; a plurality of combined alloy claw bodies 2 are fixed at equal intervals along the circumference of the shell 1 at one end of the inner surface of the shell 1; the cross section of the alloy claw body 2 along the radial direction of the shell 1 is a right-angled triangle, and a continuous triangular step surface is provided on the radial surface, which serves as a wear-resistant layer facing the axis of the shell 1.

[0039] It should be noted that, Figure 2 In the core claw structure shown, the shell 1 and the alloy claw body 2 are made of different metallic materials. The shell 1 is made of 40Cr or 42CrMo sheet metal, while the alloy claw body 2 is made of Fe-B alloy. This material selection considers not only overall strength and stability but also wear resistance, especially since the alloy claw body 2 itself possesses wear-resistant properties. This design makes... Figure 2 The structure eliminates the need for additional wear-resistant layer processing and avoids the tedious process of attaching the wear-resistant layer to the claw body, thus greatly simplifying the manufacturing process and improving production efficiency. Furthermore, since the alloy claw body 2 itself serves as the wear-resistant layer, its wear resistance far surpasses that of traditional wear-resistant layer processing methods, making the overall structure more durable and extending its service life. Therefore, Figure 2 The core claw structure not only simplifies the manufacturing process and improves production efficiency, but also enhances the durability of the product. Furthermore, the alloy claw body 2 preferably has 8 sets, with one claw in each set.

[0040] Example 2

[0041] A method for preparing a core claw as described in Example 1 includes the following steps:

[0042] (1) Use a vacuum induction melting furnace to melt alloy raw materials such as ferroboron, ferrochrome and ferromolybdenum, heat to 1600±20℃ and add deoxidizer such as pure aluminum, hold for 3-5 minutes, and then take out of the furnace at 1600~1620℃. Use sand casting to cast 8 sets (1 piece per set) of stepped alloy claw body 2. After casting and air cooling to room temperature, 8 sets (1 piece per set) of stepped alloy claw body 2 are obtained.

[0043] (2) Then select a 40Cr or 42CrMo plate with a thickness of 1-2mm. The width of the plate is consistent with the length of the core claw drawing, and the length is consistent with the circumference of the cylindrical shell on the core claw drawing.

[0044] (3) Weld the alloy claw 2 onto the plate.

[0045] (4) Finally, the plate after welding the alloy claw 2 is processed into a cylindrical shell 1 by roller molding, so that the alloy claw 2 is located on the inner surface of the shell 1, and the core claw product is obtained.

[0046] The alloy claw 2 obtained in the above preparation process is an Fe-B claw, wherein the content of B is 2wt%-3wt%, the content of Cr is 6wt%-8wt%, the content of Mo is 4wt%-6wt%, and the remainder is Fe. The length of the alloy claw 2 is consistent with the length of the plate, the width is 5-8mm, the height of the highest triangular step is 8-10mm, and the height of the other steps is consistent with the design drawings of the core claw.

[0047] In the above preparation process, ordinary Fe-based flux-cored welding wire was used, and the Fe-B claw sample was connected to the plate by manual arc welding (when the shell 1 was not molded by roller). According to the design drawings, a total of 8 sets of Fe-B claws with equal spacing were formed.

[0048] It should be noted that the following steps are also required in the preparation of the aforementioned core claws:

[0049] 1. Integrated design of claw body and wear-resistant layer

[0050] Determine the type and specific parameters of the core claw. Based on the different structures of the core claw (self-locking core claw, composite core claw, etc.), design the geometric shape and size information of the Fe-B claw body (the geometric shape of the Fe-B claw body should include the geometric parameters of the alloy claw body 2 and the geometric parameters of the wear-resistant layer).

[0051] 2. Fine-tuning of material composition and preparation of Fe-B alloy raw materials for Fe-B alloy claw body

[0052] ① Determine the material of the shell 1 of the core claw, such as 40Cr, 35CrMo, 42CrMo, etc.;

[0053] ②Based on the material information of the shell 1, the material composition of the Fe-B alloy claw 2 is finely designed and adjusted, and the content of Cr.Mo alloy elements is controlled to ensure the weldability of the claw body and the shell 1 when welding.

[0054] 3. Other

[0055] ① The Fe-B alloy claw body 2 blank is prepared by casting, and the surface to be connected to the shell 1 is machined and finished. Figure 3 (bottom surface);

[0056] ② Based on the different types of core claws, the following distinctions are made:

[0057] For the self-locking core claw, the Fe-B alloy claw body 2 is connected to the shell 1 by manual welding.

[0058] For composite core claws, Fe-B alloy secondary and tertiary claw bodies are prepared, and then the secondary and tertiary claw bodies are connected to the shell 1 by manual welding.

[0059] Example 3

[0060] Based on Example 2, an optional method for preparing a core claw is as follows:

[0061] Alloy raw materials such as ferroboron, ferrochrome, and ferromolybdenum were smelted in a vacuum induction melting furnace. After heating to 1610℃, pure aluminum was added for deoxidation, and the temperature was held for 4 minutes. The mixture was then removed from the furnace at 1600℃ and sand-cast using a mold. The mold consisted of 8 sets (1 piece per set) of stepped alloy claws 2. After casting and air cooling to room temperature, 8 sets (1 piece per set) of stepped alloy claws 2 were obtained.

[0062] Taking a standard Φ115×70×1.5mm self-locking core claw as an example, a 1.5mm thick 40Cr plate is selected. The width of the plate is 70mm (consistent with the length of the core claw drawing) and the length is 360mm (consistent with the circumference of the cylindrical shell on the core claw drawing).

[0063] The alloy claw 2 is welded onto the plate.

[0064] The sheet metal is processed into a cylindrical shell 1 using a roller plastic forming method, and the alloy claw 2 is located on the inner surface of the shell 1 to obtain the core claw product.

[0065] Alloy claw 2 is an Fe-B claw, with B content of 2-3 wt%, Cr content of 6 wt%-8 wt%, Mo content of 4 wt%-6 wt%, and the remainder being Fe. Alloy claw 2 has a length of 100 mm, a width of 6 mm, a maximum triangular step height of 9 mm, and the heights of the other steps are consistent with the design drawings of the core claw.

[0066] Using ordinary Fe-based flux-cored welding wire, the Fe-B claw samples were connected to the plate by manual arc welding. According to the design drawings, a total of 8 sets of Fe-B claws with equal spacing were formed.

[0067] Example 4

[0068] A method for preparing a core claw is as follows:

[0069] 1. According to the drawing requirements, select 40Cr or 42CrMo plates with a thickness of 12-15mm. The length should be consistent with the length of the core claw drawing, and the width should be consistent with the outer perimeter of the core claw end face.

[0070] 2. Use a milling machine or other machining methods to cut the thin sheet metal surface to 1-2mm to form claw-shaped steps (generally 8 sets of steps with equal spacing), with a step width of 5-8mm and a height of 8-10mm;

[0071] 3. Spread WC granules on the surface of the claw body steps.

[0072] 4. Use copper solder wire, tin solder wire or iron solder wire, and melt the solder wire using a plating process to connect the WC particles to the 40Cr / 42CrMo claw body.

[0073] 5. Using a roller plastic processing method, the plate-shaped blank is processed into a cylindrical shape to form a core claw product.

[0074] It should be noted that, compared with Example 4, Example 2 optimizes the machining of the claw body and the shell 1. The resulting alloy claw body 2 has its own wear-resistant layer and does not require additional processing. This breaks through the constraint of poor bonding strength between the Fe-based claw body and WC hard particle dissimilar materials in traditional core claws, and solves the problem of easy peeling of the wear-resistant weld layer in traditional core claws. This provides technical support for improving the service performance of core claws and extending their service life.

[0075] It should be noted that, by comparing Example 3 and Example 4, it can be seen that:

[0076] (1) The claw body in Example 3 can be prepared by casting, which is cheaper, while avoiding the milling process (milling from 12-15mm to 1-2mm) used in Example 4 to form the claw body steps, which greatly reduces material waste.

[0077] (2) In Example 3, the alloy claw body 2 and the shell are both made of steel and can be connected by manual arc welding. On the one hand, this avoids the dissimilar material welding connection between WC (hard alloy ceramic particles) and the steel shell in Example 4; on the other hand, the price of Fe-B alloy is only about 1 / 3 to 1 / 2 of that of WC hard alloy. Avoiding the use of WC hard alloy can effectively reduce the production cost of core claw.

[0078] Example 5

[0079] A core drill bit, equipped with the core claw shown in Example 1.

[0080] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A core claw, characterized in that, The core claw includes a shell (1) and an alloy claw body (2); The shell (1) is cylindrical, and the alloy claw (2) is installed on one end of the inner surface; Several sets of alloy claws (2) are fixed at equal intervals along the circumference of the housing (1) on the inner surface of the housing (1); The cross section of the alloy claw (2) along the radial direction of the shell (1) is a right triangle, and the radial cross section is provided with a continuous triangular stepped surface; The continuous triangular stepped surface serves as a wear-resistant layer, facing the axis of the shell (1).

2. The core claw according to claim 1, characterized in that, The alloy claw body (2) is provided in 8 groups, with 1 claw in each group.

3. A core claw according to claim 1, characterized in that, The shell (1) is made of 40Cr or 42CrMo sheet, and the alloy claw (2) is made of Fe-B alloy.

4. A method for preparing a core claw, characterized in that, The method for preparing the core claw according to any one of claims 1-3 comprises the following steps: The alloy raw materials were melted, heated to 1600±20℃, deoxidizer was added, and the temperature was held for 3-5 minutes. Then the furnace was taken out at 1600~1620℃. The raw material ingot of the alloy claw body (2) was cast by sand casting and then air-cooled to room temperature to obtain several combined gold claw bodies (2). Select 40Cr or 42CrMo plates with a thickness of 1-2mm; The alloy claw body (2) is welded onto the plate; The plate after welding the alloy claw body (2) is processed into a cylindrical shell (1) so that the alloy claw body (2) is located on the inner surface of the shell (1).

5. The method for preparing a core claw according to claim 4, characterized in that, The alloy raw materials include ferroborone, ferrochrome, and ferromolybdenum.

6. The method for preparing a core claw according to claim 4, characterized in that, In the alloy claw body (2): The content of B is 2wt%-3wt%, the content of Cr is 6wt%-8wt%, the content of Mo is 4wt%-6wt%, and the remainder is Fe.

7. The method for preparing a core claw according to claim 4, characterized in that, The deoxidizer is pure aluminum.

8. The method for preparing a core claw according to claim 4, characterized in that, The alloy claw body (2) has a width of 5-8mm and a height of 8-10mm for the highest triangular step surface.

9. A method for preparing a core claw according to claim 4, characterized in that, The alloy claw body (2) is welded onto the plate using manual arc welding, and the welding wire is Fe-based flux-cored welding wire.

10. A core drill bit, characterized in that, The core claw is equipped with any one of claims 1-3.

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