Multidirectional closed die forging valve body and manufacturing process thereof

Abstract

The application relates to the technical field of valve body preparation, in particular to a multidirectional closed die forging valve body and a preparation process thereof. The valve body is prepared through the following steps: heating steel, then upsetting to obtain a pie-shaped steel material; placing the pie-shaped steel material into a preheated closed combined die lower die cavity, driving a punch inwards by a horizontal side cylinder 1, driving a punch inwards by a horizontal side cylinder 2, pressure maintaining, die withdrawing, punching a skin, heat treatment, cooling, and obtaining a multidirectional closed die forging valve body. The multidirectional closed die forging valve body and the preparation process thereof are simple in process, high in production efficiency in one-step forming, efficient in material saving, small in machining allowance, low in machining cost, good in metal streamline of the prepared valve body, and high in strength.

Description

Technical Field

[0001] This application relates to the field of valve body manufacturing technology, specifically to a multi-directional closed die-forged valve body and its manufacturing process. Background Technology

[0002] Wellhead fittings and Christmas trees are core pressure-bearing components in key oil and gas extraction equipment. Their structure is typically a T- or L-shaped multi-port valve with side outlets, requiring long-term reliable operation under high pressure, corrosion, and alternating loads. Therefore, these valves have extremely stringent requirements for structural integrity, mechanical properties, and corrosion resistance.

[0003] Traditional casting processes, such as sand casting, can achieve complex shapes in a single process. However, this process is prone to casting defects such as shrinkage porosity, gas holes, and inclusions. Furthermore, the as-cast microstructure has coarse grains, resulting in lower density, mechanical properties, and corrosion resistance compared to forgings, making it difficult to meet the extreme reliability requirements of high-pressure, high-risk operating conditions. In addition, a large machining allowance is still required to compensate for the lack of dimensional accuracy and surface quality. Traditional multi-fire open-die forging processes use free-forging billets, followed by multiple open-die forgings. This method can achieve better metal flow lines and microstructure properties than casting and welding. However, to facilitate demolding and accommodate excess metal, flash grooves must be designed, generating and removing a large amount of flash, leading to low material utilization and significant waste. Simultaneously, to cover forging dimensional deviations, a large machining allowance is required on the surface, resulting in time-consuming and material-intensive subsequent machining, leading to high costs. Moreover, complex multi-port structures are difficult to form in a single process; metal flow lines are easily cut off at the parting line or branch pipe root, and multiple heating forging processes affect production efficiency and microstructure uniformity. Therefore, developing a production process that can achieve near-net-shape forming of the valve body, excellent internal quality, and high efficiency and material saving has become a key technological direction for meeting the needs of high-end wellhead equipment and reducing costs and increasing efficiency. Summary of the Invention

[0004] To address the aforementioned issues, the purpose of this application is to provide a multi-directional closed-type die-forged valve body and its manufacturing process. The process is simple, has high one-time molding efficiency, is highly efficient and material-saving, and the valve body produced has high strength.

[0005] To achieve the above objectives, this application provides a manufacturing process for a multi-directional closed-type die-forged valve body, comprising the following steps: S1. Heat the steel and then upset it to obtain a disc-shaped steel material; In the above process, upsetting can break the oxide scale and remove the surface iron oxide scale generated during heating through deformation, preventing it from being pressed into the interior of the forging and forming defects. Upsetting can improve the density of the material and forge together the small porosity and voids in the center of the raw material, laying the first foundation for obtaining a defect-free forging. The upsetting raw material is in the shape of a disc, which makes it easier to distribute in the mold cavity volume, ensuring that the subsequent metal can fill the complex cavity evenly and smoothly.

[0006] S2. Place the disc-shaped steel material into the lower cavity of the preheated closed combination mold. The upper mold moves downward, and the horizontal side cylinder 1 drives the punch to press inward. The horizontal side cylinder 2 drives the punch to press inward. Hold the pressure, demold, punch the connecting skin, heat treat, and cool to obtain a multi-directional closed die forging valve body.

[0007] In the above process, within a completely enclosed mold, the metal is plastically deformed in one step by the sequential extrusion of punches from multiple directions, precisely obtaining the three-dimensional shape of the valve body, including the complex internal cavity. Through multi-directional sequential loading, the metal fibers are guided to continuously distribute along the shape of the valve body and the direction of force. The upper die descends to axially extrude the blank, initially forming the outline of the upper and lower flanges of the valve body and part of the main body. The horizontal side cylinder 1 drives the side punch to extrude inward, beginning to form the side branch boss and part of the internal cavity. The horizontal side cylinder 2 drives the internal cavity punch to extrude horizontally from the other end. After extrusion is completed, the vertical main cylinder and the two horizontal cylinders simultaneously maintain pressure under the set pressure, allowing the metal to fully plastically flow and compact within the completely enclosed cavity, filling all corners.

[0008] Furthermore, the heating temperature is 1150-1200℃, and the heating time is 90-120 minutes.

[0009] Furthermore, the upsetting ratio is 1.5-2.0.

[0010] Furthermore, the preheating temperature is 200-300℃, and the time is 4-6 hours.

[0011] Furthermore, the upper mold descends at a speed of 50-150 mm / s and a pressure of 25-30 MPa.

[0012] Furthermore, the horizontal side cylinder 1 drives the punch to press inward at a speed of 10-20 mm / s and a pressure of 25-30 MPa.

[0013] Furthermore, the horizontal side cylinder 2 drives the punch to press inward at a speed of 5-15 mm / s and a pressure of 25-30 MPa.

[0014] Furthermore, the pressure holding time is 10-20 seconds.

[0015] Furthermore, the heat treatment is performed at a temperature of 1000-1100℃ for 1-2 hours.

[0016] Furthermore, the cooling is performed at a rate of 0.5-1.5°C / min to bring the temperature down to room temperature.

[0017] This application also provides a manufacturing process for a multi-directional closed-type die-forged valve body.

[0018] In summary, this application has the following beneficial effects: 1. High efficiency in one-time molding: The main body of the complex valve body is formed in a single press and a single mold through a series of multiple actions, replacing the cumbersome process of traditional free forging billets, multi-fire forging, and welding of branch pipes, which significantly shortens the production cycle.

[0019] 2. No flash, saving raw material costs: Closed die forging does not produce transverse flash, which can reduce billet consumption and improve material utilization compared to open die forging.

[0020] 3. Small machining allowance, reducing machining costs: Closed-die forging makes the dimensions of the forging close to the final dimensions of the part, especially the inner cavity of the flow channel and the shape of the flange, reducing conventional machining allowance, machining time and tool wear.

[0021] 4. Excellent metal flow lines and high strength: Multi-directional sequential molding ensures that the metal fibers are continuously distributed along the valve body contour and stress direction, and are seamlessly cut. Compared with the cut flow lines formed by cutting or welding, the fatigue strength, impact toughness, and especially the stress corrosion resistance are significantly improved, meeting the harsh working conditions of wellhead equipment. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A front view showing the structural dimensions of the multi-directional closed-type die-forged valve body prepared in this application; Figure 2 This is a side view showing the structural dimensions of the multi-directional closed-type forged valve body prepared in this application. Detailed Implementation

[0024] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this invention.

[0025] The steel described in the specific embodiments of this application is alloy steel 4130 with a diameter of 220mm.

[0026] Example 1 A manufacturing process for a multi-directional closed-circuit forged valve body includes the following steps: S1. 352.5Kg of steel is fed into a ring furnace and heated at 1150℃ for 120min. The heated steel is taken out of the furnace and radially upset on the press worktable (upsetting ratio is 1.5) to obtain a disc-shaped steel material. S2. Place the disc-shaped steel material into the lower cavity of a closed combined mold that has been preheated to 200℃ for 5 hours, and spray it with a glass-based high-temperature lubricant. The vertical main cylinder drives the upper mold to descend at a speed of 50 mm / s and a pressure of 25 MPa, closing with the lower mold. The horizontal side cylinder 1 drives the side punch to press inward at a speed of 10 mm / s and a pressure of 25 MPa. The horizontal side cylinder 2 drives the inner cavity punch to press inward at a speed of 5 mm / s and a pressure of 25 MPa. After pressing, the vertical main cylinder and the two horizontal side cylinders hold the pressure for 15 seconds. After holding the pressure, the horizontal punch retracts first, and then the upper mold returns. The forging is ejected from the lower mold by the ejection device. The forging is punched out with a mold on a press, and then held at 1050℃ for 1.5 hours. After that, it is cooled to room temperature at a rate of 1℃ / min to obtain a multi-directional closed die forged valve body.

[0027] Example 2 A manufacturing process for a multi-directional closed-circuit forged valve body includes the following steps: S1. 352.5 kg of steel is fed into a ring furnace and heated at 1170℃ for 100 min. The heated steel is taken out of the furnace and radially upset on the press worktable (upsetting ratio is 1.7) to obtain a disc-shaped steel material. S2. Place the disc-shaped steel material into the lower cavity of a closed combined mold that has been preheated at 250℃ for 5 hours, and spray it with a glass-based high-temperature lubricant. The vertical main cylinder drives the upper mold to descend at a speed of 100 mm / s and a pressure of 30 MPa, closing with the lower mold. The horizontal side cylinder 1 drives the side punch to press inward at a speed of 15 mm / s and a pressure of 30 MPa. The horizontal side cylinder 2 drives the inner cavity punch to press inward at a speed of 10 mm / s and a pressure of 30 MPa. After pressing, the vertical main cylinder and the two horizontal side cylinders hold the pressure for 15 seconds. After holding the pressure, the horizontal punch retracts first, and then the upper mold returns. The forging is ejected from the lower mold by the ejection device. The forging is punched out with a die on a press, and then held at 1050℃ for 1.5 hours. After that, it is cooled to room temperature at a rate of 1℃ / min to obtain a multi-directional closed die forged valve body.

[0028] Example 3 A manufacturing process for a multi-directional closed-circuit forged valve body includes the following steps: S1. 352.5 kg of steel is fed into a ring furnace and heated at 1200℃ for 90 min. The heated steel is then taken out of the furnace and radially upset on the press worktable (upsetting ratio of 2.0) to obtain a disc-shaped steel material. S2. Place the disc-shaped steel material into the lower cavity of a closed combined mold that has been preheated at 300℃ for 5 hours, and spray it with a glass-based high-temperature lubricant. The vertical main cylinder drives the upper mold to descend at a speed of 150 mm / s and a pressure of 30 MPa, closing with the lower mold. The horizontal side cylinder 1 drives the side punch to extrude inward at a speed of 20 mm / s and a pressure of 30 MPa. The horizontal side cylinder 2 drives the inner cavity punch to extrude inward at a speed of 15 mm / s and a pressure of 30 MPa. After extrusion, the vertical main cylinder and the two horizontal side cylinders hold the pressure for 15 seconds. After holding the pressure, the horizontal punch retracts first, and then the upper mold returns. The forging is ejected from the lower mold using an ejector device. The forging is punched out with a die on a press, and then held at 1050℃ for 1.5 hours. After that, it is cooled to room temperature at a rate of 1℃ / min to obtain a multi-directional closed die forged valve body.

[0029] Compare with Example 1 The difference between this comparative example and Example 3 is that the vertical master cylinder drives the upper die at a speed of 180 mm / s. The manufacturing process of a multi-directional closed-type die-forged valve body in this comparative example includes the following steps: S1. 352.5 kg of steel is fed into a ring furnace and heated at 1200℃ for 90 min. The heated steel is then taken out of the furnace and radially upset on the press worktable (upsetting ratio of 2.0) to obtain a disc-shaped steel material. S2. Place the disc-shaped steel material into the lower cavity of a closed combined mold that has been preheated at 300℃ for 5 hours, and spray it with a glass-based high-temperature lubricant. The vertical main cylinder drives the upper mold to descend at a speed of 180 mm / s and a pressure of 30 MPa, closing with the lower mold. The horizontal side cylinder 1 drives the side punch to extrude inward at a speed of 20 mm / s and a pressure of 30 MPa. The horizontal side cylinder 2 drives the inner cavity punch to extrude inward at a speed of 15 mm / s and a pressure of 30 MPa. After extrusion, the vertical main cylinder and the two horizontal side cylinders hold the pressure for 15 seconds. After holding the pressure, the horizontal punch retracts first, and then the upper mold returns. The forging is ejected from the lower mold using an ejector device. The forging is punched out with a die on a press, and then held at 850℃ for 1.5 hours. After that, it is cooled to room temperature at a rate of 1℃ / min to obtain a multi-directional closed die forged valve body.

[0030] Compare with Example 2 This comparative example uses a casting method to prepare the valve body, including the following steps: S1. 352.5 kg of steel is smelted in a medium-frequency induction furnace at a melting temperature of 1600℃ to obtain molten steel; S2. Pour molten steel into a mold preheated to 900℃ (pouring temperature is 1530℃). After pouring, place the mold in a heat preservation box and cool it to 150℃ at 0.5℃ / min. Then remove the sand by flame cutting. Then keep it at 1120℃ and 110MPa for 3 hours. After cooling to room temperature, the valve body is obtained.

[0031] Performance testing Functional tests were performed on the valve bodies prepared in Examples 1-3 and Comparative Examples 1-2.

[0032] Tensile strength test: The tensile strength was measured in accordance with ASTM A370-2024 standard. Impact strength test: Take material from the valve body extension section and process it into a standard Charpy V-notch impact specimen with the notch direction perpendicular to the main deformation direction of the forging. Cool the specimen to -46℃ and break it in one go with a pendulum on the impact testing machine. Read the absorbed energy value and calculate the impact energy. Hydrostatic pressure test: Seal all channels of the machined valve body with special test plugs and sealing rings, fill with water and purge air, use a high-pressure pump to slowly increase the pressure to 103.5 MPa, hold the pressure for 5 minutes, and observe the valve body surface for any leakage, water droplets, or permanent deformation. The test results are shown in Table 1: Table 1 ; As shown in Table 1, the valve body prepared in this application has strong mechanical properties, high tensile strength, and high impact strength. No leakage, water droplets, or permanent deformation were observed after hydrostatic pressure testing, indicating strong pressure-bearing capacity of the valve body. The difference between Comparative Example 1 and Example 3 is that the vertical master cylinder drives the upper mold at a speed of 180 mm / s. Excessive upper mold speed affects subsequent molding, leading to reduced mechanical properties, lower tensile strength, and lower impact strength. While no leakage or water droplets were observed after hydrostatic pressure testing, permanent deformation was observed, indicating that the valve body prepared in Comparative Example 1 has weak pressure-bearing capacity and is inferior to Example 3. Comparative Example 2 uses a casting method to prepare the valve body. The mechanical properties of the prepared valve body are inferior to those of the valve body prepared in Example 3. While no leakage or water droplets were observed after hydrostatic pressure testing, permanent deformation was observed, indicating that the valve body prepared in Comparative Example 2 has weak pressure-bearing capacity and is inferior to Example 3.

[0033] The above description is merely an example and illustration of the concept of this application. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the inventive concept or exceed the scope defined in the claims, they should all fall within the protection scope of this application.

Claims

1. A manufacturing process for a multi-directional closed-type die-forged valve body, characterized in that, Includes the following steps: S1. Heat the steel and then upset it to obtain a disc-shaped steel material; S2. Place the disc-shaped steel material into the lower cavity of the preheated closed combination mold. The upper mold moves downward, and the horizontal side cylinder 1 drives the punch to press inward. The horizontal side cylinder 2 drives the punch to press inward. Hold the pressure, demold, punch the connecting skin, heat treat, and cool to obtain a multi-directional closed die forging valve body.

2. The manufacturing process of a multi-directional closed-type die-forged valve body according to claim 1, characterized in that, The heating process involves a heating temperature of 1150-1200℃ and a heating time of 90-120 minutes.

3. The manufacturing process of a multi-directional closed-type die-forged valve body according to claim 1, characterized in that, The upsetting process has an upsetting ratio of 1.5-2.

0.

4. The manufacturing process of a multi-directional closed-type die-forged valve body according to claim 1, characterized in that, The preheating temperature is 200-300℃, and the time is 4-6 hours.

5. The manufacturing process of a multi-directional closed-type die-forged valve body according to claim 1, characterized in that, The upper mold descends at a speed of 50-150 mm / s and a pressure of 25-30 MPa.

6. The manufacturing process of a multi-directional closed-type die-forged valve body according to claim 1, characterized in that, The horizontal side cylinder 1 drives the punch to press inward at a speed of 10-20 mm / s and a pressure of 25-30 MPa.

7. The manufacturing process of a multi-directional closed-type die-forged valve body according to claim 1, characterized in that, The horizontal side cylinder 2 drives the punch to press inward at a speed of 5-15 mm / s and a pressure of 25-30 MPa.

8. The manufacturing process of a multi-directional closed-type die-forged valve body according to claim 1, characterized in that, The heat treatment is performed at a temperature of 1000-1100℃ for 1-2 hours.

9. The manufacturing process of a multi-directional closed-type die-forged valve body according to claim 1, characterized in that, The cooling process involves reducing the temperature to room temperature at a rate of 0.5-1.5°C / min.

10. A multi-directional closed-circuit forged valve body prepared by a manufacturing process according to any one of claims 1-9.

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