A forming process and die for a center tube forging for oil drilling rigs

Abstract

The present invention discloses a center tube forging forming process and die for oil drilling rigs. A cylindrical steel billet is forged into a center tube forging through a process flow that includes raw material inspection, blanking, die preheating, billet heating, die forging, inspection, and post-forging cooling. The center tube forging is forged and formed using a forging die, which comprises an upper die, an extrusion sleeve, and a lower die. The upper die, the extrusion sleeve, and the lower die respectively form the upper end, flange, and lower section of the center tube forging. This center tube forging forming process and die for oil drilling rigs utilizes a single-fire heating, upsetting, and extrusion forming method, which reduces processing difficulty, reduces material consumption, and improves production efficiency. The dimensions of the forged center tube forging are closer to those of the center tube parts, resulting in a smaller machining allowance, a higher product qualification rate, and lower costs. Furthermore, product performance is improved, resulting in a longer service life.

Description

Technical Field

[0001] The invention relates to the field of center tube processing for oil drilling rigs, and in particular to a center tube forging forming process and a die for the oil drilling rig. Background Art

[0002] In oil drilling, a drilling rig primarily drives the drill tool to break rock, penetrate underground, and drill a wellbore to a specified depth, allowing oil or gas extraction equipment to retrieve oil or natural gas. A typical oil drilling rig primarily consists of a power unit, transmission unit, work unit, and auxiliary equipment. The drill pipe in the work unit is a crucial component for the rig to penetrate the ground.

[0003] The drill pipe on an oil rig is connected to the transmission mechanism via a central tube with a large flange. Tapered threaded sections are located at the top and bottom of the tube, making the connection easy and stable. Due to the working environment of the drill pipe, the central tube is a consumable part. Therefore, to prevent breakage due to excessive wear and tear, the central tube must be regularly inspected and replaced to ensure drill pipe reliability.

[0004] Due to the structural limitations of the center tube, the center tube is currently generally processed by free forging and die forging with rods pulled at both ends and upsetting in the middle. The cylindrical steel billet is upset in the middle by pulling rods at both ends to form a semi-finished product with an outer contour similar to the outer contour of the center tube. The semi-finished product is then turned by machining to meet the dimensional accuracy requirements of the center tube. A large amount of excess material must be turned away, resulting in a large amount of material waste and increased production costs. In addition, rod pulling is relatively difficult. When the end is pulled, the pulled part must have a sufficient length, and its length must not be less than 1 / 3 of the diameter. Otherwise, metal shrinkage is likely to occur during rod pulling, resulting in a hollow and scrapped. At the same time, in order to pull out the rod, the mass of the pulled part has to be increased, resulting in material waste. The processing efficiency is also relatively low, and the product performance can only meet the corresponding requirements, and the service life is short. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a forming process and a die for a center pipe forging for an oil drilling rig, which has the advantages of less excess removal at a later stage, reduced cost and improved production efficiency and product performance.

[0006] In order to solve the above technical problems, the present invention is achieved through the following technical solutions: A process for forming a central tube forging for an oil drilling rig, comprising the following steps:

[0007] A. Raw material inspection: Re-inspect the raw materials to ensure that they meet the corresponding requirements;

[0008] B. Blanking: Cutting is performed on sawing equipment to form cylindrical billets that meet blanking standards, and burrs and cracks on the billet surface are removed;

[0009] C. Die preheating: Place the forging die into the heating furnace for preheating;

[0010] D. Billet heating: The cylindrical billet from the sawing machine is placed into the heating furnace for heating by the robot, and is taken out by the robot after reaching the temperature;

[0011] E. Die Forging: After the preheated forging die is transferred from the heating furnace to the hydraulic press and installed, the removed cylindrical steel billet is first placed in the forging die, lubricated and positioned. A mixture of sawdust and graphite powder is evenly sprinkled on the upper surface of the cylindrical steel billet. The hydraulic press then controls the upper die assembly of the forging die to be pressed downward. During the downward pressing process, compressed air is used to remove the detached oxide scale. After the prescribed stroke is reached, the center tube forging is formed. The hydraulic press then lifts the upper die assembly during the return stroke. The center tube forging is then ejected from the lower die by the hydraulic press's ejector cylinder and removed from the lower die cavity by a manipulator.

[0012] F. Inspection: After a center tube forging is completed, the inspector uses calipers and steel rulers to inspect the hot center tube forging to ensure that the dimensions of the center tube forging meet the requirements of the drawing;

[0013] G. Cooling after forging: Cooling is carried out by air cooling after forging.

[0014] Preferably, the diameter D of the columnar steel billet in step A is 500 mm, the length L is 770 mm, and the weight is 1188 kg.

[0015] Preferably, in step C, the preheating temperature of the forging die is 350° C., and the preheating time is ≥ 6 h.

[0016] Preferably, in step D, the columnar steel billet is heated to 1180° C. and kept at this temperature for 2 hours.

[0017] A center tube forging die for an oil drilling rig comprises an upper pad and a lower pad corresponding vertically up and down, an upper die is provided at the bottom center of the upper pad, and a lower die is provided at the top center of the lower pad, and both the upper die and the lower die are cylindrical structures, corresponding to each other and concentric with each other; a material withdrawal hole communicating up and down is provided at the center of the lower pad, a material withdrawal device that slides with it up and down is provided in the material withdrawal hole, an upper die cavity for forming the upper end of the center tube forging is provided at the bottom center of the upper die, and a lower die cavity for forming the lower section of the center tube forging is provided at the top center of the lower die, an extrusion sleeve is provided on the outside of the upper die for sliding with it up and down, and the extrusion sleeve is provided with a material withdrawal device that slides with it up and down. The center is provided with a flange mold cavity for forming the flange in the middle section of the center tube forging. The flange mold cavity is a cylindrical structure, which is connected to the upper and lower ends of the extrusion sleeve. The upper mold is sleeved in the flange mold cavity, and its outer diameter matches the diameter of the flange mold cavity and slides with each other; a flat connecting plate is provided on each of the left and right sides of the outside of the extrusion sleeve, and the two connecting plates are symmetrical on the left and right. The connecting plates are provided with guide sliding holes connected up and down, and a screw that slides with it is provided in the guide sliding hole. The top of the screw is fixedly connected to the upper pad, and a limiting nut that threads with it is provided on the outer side of the lower end. The bottom of the connecting plate is limited by the limiting nut.

[0018] Preferably, the screw is a T-shaped screw, and the upper pad is provided with a countersunk hole that matches the head structure of the T-shaped screw, and the countersunk hole connects the upper and lower ends of the upper pad.

[0019] Preferably, an outward limiting protrusion is provided along the periphery of the outer side of the upper end of the upper mold.

[0020] Preferably, a limiting cavity capable of being sleeved and fitted with the outer side of the lower die is provided at the bottom of the extrusion sleeve, and the limiting cavity is communicated with the flange die cavity.

[0021] Preferably, the lower mold cavity is connected to the upper and lower ends of the lower mold, the head of the lower mold cavity is funnel-shaped, and the bottom corresponds to the material withdrawal hole.

[0022] Preferably, the material removal device consists of an integrally formed plug and a push rod, the plug is located directly above the push rod, its diameter is larger than the diameter of the push rod, and it has a "T"-shaped structure. The plug can slide up and down with the lower mold cavity, and the shape of the material removal hole structure is consistent with the "T"-shaped structure of the material removal device, and the top surface of the plug is flush with the top surface of the lower pad.

[0023] Compared with the prior art, the present invention is advantageous in that: the center tube forging forming process and die for oil drilling rigs adopts a single-fire heating and upsetting extrusion forming method, which reduces the processing difficulty and improves production efficiency. The size of the forged center tube forging is closer to the size of the center tube parts, the subsequent machining allowance is small, the product qualification rate is high, the cost is reduced, and the product performance is also improved, with a longer service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic structural diagram of a central tube forging forming die for an oil drilling rig according to the present invention;

[0025] Figure 2 This is a schematic structural diagram of the columnar steel billet in the utility model;

[0026] Figure 3 This is a forging process flow chart of a forming die for a center tube forging for an oil drilling rig of the present invention;

[0027] Figure 4 The present invention is a schematic structural diagram of a central tube forging for an oil drilling rig.

[0028] In the figure: 1. Upper pad; 1-1. Countersunk hole; 2. Lower pad; 2-1. Material withdrawal hole; 3. Upper die; 3-1. Upper die cavity; 3-2. Limiting protrusion; 4. Lower die; 4-1. Lower die cavity; 5. Extrusion sleeve; 5-1. Flange die cavity; 5-2. Limiting concave cavity; 6. Screw; 7. Connecting plate; 7-1. Guide slide hole; 8. Limiting nut; 9. Material withdrawal device; 10. Columnar billet; 11. Center tube forging. DETAILED DESCRIPTION

[0029] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Figure 1The die for a center tube forging for an oil drilling rig is shown, comprising an upper plate 1 and a lower plate 2 corresponding vertically to each other. An upper die 3 is provided at the bottom center of the upper plate 1, and a lower die 4 is provided at the top center of the lower plate 2. The upper die 3 and the lower die 4 are both cylindrical structures, corresponding to each other and concentric with each other; a material withdrawal hole 2-1 communicating with each other is provided at the center of the lower plate 2, and a material withdrawal device 9 that slides with the material withdrawal hole 2-1 is provided inside the material withdrawal hole 2-1, an upper die cavity 3-1 for forming the upper end of the center tube forging 11 is provided at the bottom center of the upper die 3, and a lower die cavity 4-1 for forming the lower section of the center tube forging 11 is provided at the top center of the lower die 4, and an extrusion sleeve 5 that slides with the material withdrawal hole 2-1 is provided on the outside of the upper die 3. A flange mold cavity 5-1 for forming the flange of the middle section of the center tube forging 11 is provided in the center. The flange mold cavity 5-1 is a cylindrical structure, which is connected to the upper and lower ends of the extrusion sleeve 5. The upper mold 3 is sleeved in the flange mold cavity 5-1, and its outer diameter matches the diameter of the flange mold cavity 5-1 and slides with each other; a flat connecting plate 7 is provided on each of the left and right sides of the outside of the extrusion sleeve 5, and the two connecting plates 7 are symmetrical on the left and right. A guide slide hole 7-1 connected to the upper and lower parts is provided on the connecting plate 7, and a screw 6 that slides with it is provided in the guide slide hole 7-1. The top of the screw 6 is fixedly connected to the upper pad 1, and a limiting nut 8 that threads with it is provided on the outer side of the lower end. The bottom of the connecting plate 7 is limited by the limiting nut 8.

[0031] In order to facilitate the connection of the screw 6 to the upper pad 1 and facilitate installation and disassembly, the screw 6 is a T-shaped screw, and the upper pad 1 is provided with a countersunk hole 1-1 that matches the head structure of the T-shaped screw. The countersunk hole 1-1 connects the upper and lower ends of the upper pad 1.

[0032] In order to ensure that the upper die 3 has the function of a punch and at the same time ensure the position movement between it and the extrusion sleeve 5 during forging, an outward limiting protrusion 3-2 is provided along the periphery of the outer side of the upper end of the upper die 3.

[0033] In order to ensure that the upper die 3 and the lower die 4 can be centered up and down, and at the same time prevent the upper die 3 and the extrusion sleeve 5 from over-forging the cylindrical steel billet 10 to cause waste, a limiting cavity 5-2 is provided at the bottom of the extrusion sleeve 5, which can be mutually fitted with the outer side of the lower die 4, and the limiting cavity 5-2 is connected to the flange die cavity 5-1.

[0034] In order to ensure that the columnar steel billet 10 can be positioned on the lower die 4 and facilitate the easy forming of the columnar steel billet 10, the lower die cavity 4-1 connects the upper and lower ends of the lower die 4, the head of the lower die cavity 4-1 is funnel-shaped, and the bottom corresponds to the material withdrawal hole 2-1.

[0035] In order to facilitate the withdrawal of the columnar steel billet 10 after it is forged into the center tube forging 11, and to ensure that the bottom of the center tube forging 11 is not easily damaged by pressure during withdrawal, the withdrawal device 9 is composed of an integrally formed plug and a push rod. The plug is located directly above the push rod, and its diameter is larger than the diameter of the push rod, forming a "T"-shaped structure. The bottom of the push rod is connected to the ejection cylinder, and the plug can slide up and down with the lower die cavity 4-1. The structural shape of the withdrawal hole 2-1 is consistent with the "T"-shaped structure of the withdrawal device 9, and the top surface of the plug is flush with the top surface of the lower pad 2.

[0036] In order to facilitate the installation, disassembly and replacement of damaged parts of various components of the mold and reduce the manufacturing cost of the mold, the upper mold 3 is fixed to the bottom of the upper pad 1 by bolts, and the lower mold 4 is directly placed on the lower pad 2, or it can also be fixed in position by bolts, or a cavity is provided on the top of the lower pad 2 that matches the diameter of the bottom of the lower mold 4, and the lower mold 4 is limited in the circumferential direction by the cavity.

[0037] In combination with the above-mentioned center tube forging die, the specific processing steps of the center tube forging are as follows:

[0038] A. Raw material inspection: Re-inspect the raw materials to ensure that they meet the corresponding requirements;

[0039] B. Cutting: Cutting is performed on the sawing equipment into cylindrical steel billets 10 with a diameter D of 500 mm, a length L of 770 mm, and a weight of 1188 kg that meet the cutting standards (see the attached Figure 2 ), and remove burrs on the billet surface, eliminate surface cracks and other defects;

[0040] C. Die preheating: Place the forging die in a heating furnace for preheating. The preheating temperature of the forging die is 350°C and the preheating time is ≥ 6 hours.

[0041] D. Billet heating: The cylindrical billet 10 off the sawing machine is placed into a heating furnace for heating by a manipulator. The cylindrical billet 10 is heated to 1180°C and kept at this temperature for 2 hours. After reaching the temperature, it is taken out by the manipulator;

[0042] E. Die Forging: After the preheated forging die is transferred from the heating furnace to the hydraulic press and installed, the columnar steel billet 10 is first placed in the forging die, lubricated and positioned. The sawdust and graphite powder mixture is evenly sprinkled on the upper surface of the columnar steel billet 10. Then, the hydraulic press controls the forging die upper die assembly to press down. During the pressing process, compressed air is used to remove the detached oxide scale. After the prescribed stroke is reached, the die is formed. Figure 4 As shown in the center tube forging 11, the hydraulic press lifts the upper die assembly during the return stroke, and then uses the hydraulic press's ejector cylinder to eject the center tube forging 11 from the lower die 4, and then uses the manipulator to remove the center tube forging 11 from the lower die cavity 4-1;

[0043] F. Inspection: After the forging of a center tube forging 11 is completed, the inspector uses calipers and a steel ruler to inspect the hot center tube forging 11 to ensure that the dimensions of the center tube forging 11 meet the requirements of the drawing;

[0044] G. Cooling after forging: Cooling is carried out by air cooling after forging.

[0045] like Figure 3 As shown, the specific working principle of the forging die in step E die forging is as follows: the preheated upper pad 1 and lower pad 2 are fixedly installed on the hydraulic press, and then the preheated cylindrical steel billet 10 is placed in the top center of the lower die cavity 4-1 in the lower die 4, and the bottom of the cylindrical steel billet 10 is positioned through the funnel-shaped opening at the top of the lower die cavity 4-1, and then the press pressure is adjusted to control the upper pad 1 to move downward, and then the flange die cavity 5-1 of the extrusion sleeve 5 is sleeved on the outside of the cylindrical steel billet 10, and after the limiting concave cavity 5-2 at the bottom of the extrusion sleeve 5 is completely sleeved on the top outer end of the lower die 4, the upper die 3 continues to press under the action of the upper pad 1. It continues to move downward, and after the upper die cavity 3-1 at the top of the upper 3 contacts the top of the cylindrical steel billet 10, it continues to press down until the upper die cavity 3-1, the flange die cavity 5-1 and the lower die cavity 4-1 extrude the cylindrical steel billet 10 into a center tube forging 11. After forging is completed, the hydraulic press drives the upper pad 1 and the upper die 3 to reset upward. At the same time, the extrusion sleeve 5 connected to the connecting plate 7 is driven upward by the screw 6 and the limiting nut 8 to limit the connecting plate 7 until it is completely reset and the extrusion sleeve 5 is completely separated from the center tube forging 11. Then, the ejection cylinder drives the ejection device 9 upward to eject the center tube forging 11 in the lower die cavity 4-1.

[0046] This center tube forging forming process and mold for oil drilling rigs adopts a single-fire heating and upsetting extrusion forming method, which reduces the processing difficulty and improves production efficiency. The size of the forged center tube forging is closer to the size of the center tube parts, the subsequent machining allowance is small, the product qualification rate is high, the cost is reduced, and the product performance is also improved, with a longer service life.

[0047] It should be emphasized that the above are only preferred embodiments of the present invention and do not limit the present invention in any form. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A center tube forging die for an oil drilling rig, comprising an upper pad (1) and a lower pad (2) corresponding vertically to each other, an upper die (3) being provided at the bottom center of the upper pad (1), and a lower die (4) being provided at the top center of the lower pad (2), the upper die (3) and the lower die (4) both being cylindrical in structure, corresponding to each other and being concentric with each other; a material return hole (2-1) communicating with each other from top to bottom is provided at the center of the lower pad (2), and a material return device (9) slidingly matched with the material return hole (2-1) is provided in the material return hole (2-1), wherein the material return hole (2-1) is characterized in that: The center of the bottom of the upper die (3) is provided with an upper die cavity (3-1) for forming the upper end of the central tube forging (11), and the outer side of the upper end of the upper die (3) is provided with an outward limiting protrusion (3-2) along its periphery. The center of the top of the lower die (4) is provided with a lower die cavity (4-1) for forming the lower section of the central tube forging (11), and the lower die cavity (4-1) is connected to the upper and lower ends of the lower die (4). The head of the lower die cavity (4-1) is funnel-shaped, and the bottom is connected to the material withdrawal hole. (2-1) correspond to each other, the outer portion of the upper die (3) is sleeved with an extrusion sleeve (5) that slides with it up and down, and the center of the extrusion sleeve (5) is provided with a flange die cavity (5-1) for forming the flange of the middle section of the center tube forging (11), and the flange die cavity (5-1) is in a cylindrical structure, which communicates with the upper and lower ends of the extrusion sleeve (5), and the upper die (3) is sleeved in the flange die cavity (5-1), and its outer diameter is consistent with the diameter of the flange die cavity (5-1) and is Mutually slidingly matched; the bottom of the extrusion sleeve (5) is provided with a limiting cavity (5-2) that can be mutually sleeved and matched with the outer side of the lower mold (4), and the limiting cavity (5-2) is communicated with the flange mold cavity (5-1); a flat connecting plate (7) is provided on each of the left and right sides of the outside of the extrusion sleeve (5), and the two connecting plates (7) are symmetrical. The connecting plate (7) is provided with a guide sliding hole (7-1) that is connected to the upper and lower parts, and a screw (6) that is slidably matched with the guide sliding hole (7-1) is provided in the guide sliding hole (7-1), and the screw (6) is a T-shaped screw. The upper pad (1) is provided with a countersunk hole (1-1) that matches the head structure of the T-shaped screw, and the countersunk hole (1-1) is connected to the upper and lower ends of the upper pad (1); the top of the screw (6) is fixedly connected to the upper pad (1), and a limiting nut (8) that is threadedly matched with the screw is provided on the outer side of the lower end, and the bottom of the connecting plate (7) is limited by the limiting nut (8).

2. A center pipe forging die for oil drilling rigs according to claim 1, characterized in that: The ejection device (9) is composed of an integrally formed ejector head and an ejector rod. The ejector head is located directly above the ejector rod, and its diameter is larger than that of the ejector rod, forming a "T"-shaped structure. The ejector head can slide up and down with the lower mold cavity (4-1). The ejection hole (2-1) has a structural shape that matches the "T"-shaped ejection device (9), and the top surface of the ejector head is flush with the top surface of the lower pad (2).

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