Pump shaft forging forming die and method

Abstract

The invention relates to the field of forging forming, in particular to a pump shaft forging forming die and method, and the die comprises a lower die, a first extrusion mechanism and a second extrusion mechanism; the lower die is provided with a forming cavity matched with the lower part of the pump shaft in shape; the first extrusion mechanism comprises an upper-section outer die and a punch, the upper-section outer die is arranged at the top of the lower die, and the punch is arranged along an inner cavity of the upper-section outer die; the second extrusion mechanism comprises a pier head upper die, a binding face matched with the top face of the lower die is arranged at the bottom of the pier head upper die, and a forming groove used for forming the upper portion of the pump shaft is formed in the binding face. Through step-by-step and zone-by-zone extrusion, the slender rod structure on the lower portion of the pump shaft is firstly formed, then the flange and the upper portion of the pump shaft are formed, integrated forming of the slender rod and the flange is achieved, the later-stage machining amount is reduced, and the production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of forging, and in particular to a pump shaft forging die and method. Background Art

[0002] As the core transmission component of the fluid conveying system, the turbine pump shaft must withstand high speeds, high torques, and complex alternating loads. These requirements place strict demands on the material's structural density, mechanical strength, and fatigue life. Currently, the industry's mainstream production processes face the following technical bottlenecks: The main process defects of free forging: Conventional production mainly relies on free forging, which is gradually formed through multiple forgings. This method requires a 20-30% processing allowance to be reserved to ensure the integrity of the forming, resulting in low material utilization and a long time-consuming subsequent machining. At the same time, the quality of forgings is highly dependent on the experience level of the operators. Under the influence of human factors such as forging force, temperature control, and deformation rhythm, the product qualification rate is generally lower than 85%.

[0003] Existing extrusion technology limitations: Although some companies have tried to use extrusion technology, such technology is mostly limited to forming uniform cross-section or simple stepped shafts. Figure 1 The figure shows a steam turbine pump shaft 1, which includes an upper pump shaft portion 11, a flange 12, and a lower pump shaft portion 13. The lower pump shaft portion is a slender rod structure. The traditional extrusion process has the following technical bottlenecks when processing this "slender rod + flange" composite structure: 1. When forming the slender rod, the metal flow resistance is large, which can easily lead to insufficient filling or surface cracks; 2. The metal flow in the transition area between the flange and the rod is not coordinated, resulting in uneven structure. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problems that traditional free forging and existing extrusion processes cannot effectively form a turbine pump shaft with a composite structure of a slender rod and a flange, and there are technical bottlenecks such as insufficient filling, low production efficiency and uneven structure, and to provide a pump shaft forging die and method.

[0005] In a first aspect, the present invention provides a pump shaft forging die, comprising a lower die, a first extrusion mechanism, and a second extrusion mechanism; Lower die: equipped with a molding cavity that matches the shape of the lower part of the pump shaft; The first extrusion mechanism comprises an upper outer die and a punch, wherein the upper outer die is arranged on the top of the lower die, and the punch is arranged along the inner cavity of the upper outer die; The second extrusion mechanism comprises an upper die on the pier head, wherein the bottom of the upper die is provided with a fitting surface adapted to the top surface of the lower die, and the fitting surface is provided with a forming groove for forming the upper part of the pump shaft.

[0006] The application discloses a pump shaft forging forming die, which realizes the integral precision forming of a steam turbine pump shaft with a flange and an elongated rod composite structure through special structure design of twice extrusion forming. First extrusion (rod forming): a first extrusion mechanism (upper outer die + punch) is used to press the blank into a forming cavity of a lower die to form an elongated rod part of the pump shaft; Second extrusion (flange forming): a second extrusion mechanism (header upper die) is used to extrude the upper part of the blank, so that the metal flows to the forming groove and the area between the header upper die and the lower die, thereby forming the pump shaft flange and the upper part of the pump shaft; Ejection demolding: an ejection mechanism (ejection rod) is used to eject the finally formed forging from the die.

[0007] Preferably, the forming groove side wall is designed as a conical surface, and the large end of the conical surface is arranged towards the lower die.

[0008] The conical surface of the forming groove side wall can guide the material flow to the area between the header upper die and the lower die during the extrusion process, so that the flange part of the pump shaft is more easily formed.

[0009] Preferably, the forming cavity comprises a conical section and a cylindrical section which are sequentially communicated, and the cylindrical section is used to form the long rod part of the lower part of the pump shaft.

[0010] The design of the conical section helps to guide the blank to deform gradually during the extrusion process, reduces the metal flow resistance, avoids stress concentration, improves the uniformity of metal filling, and the excess material of the forging formed through the conical section can be removed through machining in the later stage, and the cylindrical section ensures the dimensional accuracy and surface finish of the long rod part of the pump shaft.

[0011] Preferably, a limiting section is arranged at the upper part of the conical section, and the bottom of the upper section outer die is provided with a protrusion which is matched with the limiting section.

[0012] The cooperation of the limiting section and the protrusion can accurately control the relative position of the upper section outer die and the lower die, avoid die misalignment, and ensure the coaxiality and dimensional consistency of the forging.

[0013] Preferably, the end of the cylindrical section connected with the conical section is provided with an extrusion section, and the diameter of the extrusion section is smaller than that of the cylindrical section.

[0014] The diameter reduction design of the extrusion section causes the local deformation of the blank when passing through, reduces the contact area of the blank and the die side wall, thereby significantly reducing the friction resistance, and avoiding the filling difficulty or surface cracks caused by long-distance friction in the traditional constant-diameter die.

[0015] Preferably, a correction section is arranged at the middle part of the cylindrical section, and the diameter of the correction section is matched with that of the extrusion section.

[0016] The correction section can fine-tune the diameter of the lower part of the extruded forging, ensure the perpendicularity and straightness of the long rod part, and reduce the subsequent machining requirements.

[0017] Preferably, the cylindrical section is provided with an embedding section at one end away from the tapered section, which is matched with the upper diameter of the ejection rod.

[0018] The embedding section is designed to enable the ejection rod to enter a part of the forming cavity, with a stroke of the length of the embedding section, facilitating the ejection rod to eject the formed blank.

[0019] In a second aspect, the present application provides a pump shaft forging forming method, comprising the following steps: S1, an upper section outer die is arranged at the top of the lower die, and the blank is pressed into the forming cavity of the lower die by the punch along the inner cavity of the upper section outer die to form the lower part of the pump shaft; S2, the upper section outer die is removed, a heading upper die matched with the shape of the upper part of the pump shaft is connected to the punch, and the blank is pressed by the heading upper die to flow to the area between the heading upper die and the lower die to form the flange and the upper part of the pump shaft.

[0020] The pump shaft forging forming method of the present application limits the upper part of the blank by the upper section outer die in step S1, and presses the blank into the forming cavity of the lower die by the punch, so that the filling of the forming cavity is more compact, and the forming quality of the lower part of the pump shaft is improved; in step S2, the blank is extruded by the heading upper die, and the blank flows to the area between the heading upper die and the lower die to form the flange part of the pump shaft; the method forms the slender rod part and the flange part of the pump shaft in a step-by-step and zoned manner, realizes the integrated forming of the slender rod and the flange, and reduces the amount of subsequent machining.

[0021] Preferably, a first heating process is arranged before step S1, in which the lower part of the blank is heated.

[0022] By heating only the lower part of the blank (corresponding to the forming area of the lower part of the pump shaft), it is ensured that the material in this area reaches the optimal plastic deformation temperature (1100±10℃), and the flange and the area above it are not heated, so that the rigidity of the upper part of the blank can be maintained, the contact instability between the punch and the upper part of the blank is prevented, and the problem that the upper section outer die is difficult to remove subsequently is solved.

[0023] Preferably, a second heating process is arranged between steps S1 and S2, in which the upper part of the blank is heated.

[0024] By heating only the upper part of the blank (corresponding to the upper part of the pump shaft and the forming area of the flange structure), the material in this area is ensured to reach the optimal plastic deformation temperature (1100±10℃), and the lower part of the pump shaft is not heated, which can maintain the rigidity of the lower part of the blank and prevent the deformation of the lower part of the blank during extrusion, while avoiding the problem of grain growth caused by repeated heating of the upper part of the blank and the lower part of the blank.

[0025] Compared with the prior art, the beneficial effects of the present application are: 1. The present application provides a pump shaft forging forming die, which realizes the integrated forming of the slender rod and the flange by step-by-step and zoned extrusion, and reduces the amount of machining in the later stage. 2. The present application provides a pump shaft forging forming die, which only needs two heating times to form a steam turbine pump shaft with a flange and a slender rod structure, improves production efficiency, reduces energy consumption by 30%, and prolongs the service life of the die. 3. The present application provides a pump shaft forging forming die, which realizes zoned forming, reduces the metal flow resistance during forming of the slender rod part, and improves the forming quality of the slender rod part. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a structural schematic diagram of a steam turbine pump shaft; Figure 2 is a sectional structure schematic diagram of the first extrusion mechanism operation process starting stage of the present application; Figure 3 is a sectional structure schematic diagram of the first extrusion mechanism operation process ending stage of the present application; Figure 4 is a sectional structure schematic diagram of the second extrusion mechanism operation process starting stage of the present application; Figure 5 is a sectional structure schematic diagram of the second extrusion mechanism operation process ending stage of the present application; Figure 6 is a sectional structure schematic diagram of the lower die of the present application; Figure 7 is a sectional structure schematic diagram of the upper segment outer die of the present application; Figure 8 is a sectional structure schematic diagram of the second extrusion mechanism of the present application; Markings in the figure: 1 - turbine pump shaft, 11 - upper pump shaft portion, 12 - flange, 13 - lower pump shaft portion, 2 - lower die, 21 - forming cavity, 211 - tapered section, 212 - cylindrical section, 213 - limiting section, 214 - extruding section, 215 - correcting section, 216 - embedding section, 3 - first extruding mechanism, 31 - upper section outer die, 311 - boss, 32 - punch, 4 - second extruding mechanism, 41 - forming groove, 5 - ejection mechanism, 51 - ejector rod, 52 - pad, 6 - blank. DETAILED DESCRIPTION

[0027] The application will be further described below in connection with specific embodiments. However, it should be understood that the above-mentioned subject matter of the application is not limited to the following embodiments, and any technology implemented based on the content of the application falls within the scope of the application.

[0028] In the description of the embodiments of the application, the terms indicating the orientation or positional relationship of "upper", "lower", "left", "right", "center", "inner", "outer", etc. are expressed based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the product / device / apparatus is usually used. These terms of orientation or positional relationship are only for the convenience of describing the application scheme or simplifying the description in the embodiments, and for the convenience of the skilled person to quickly understand the scheme, and are not intended to indicate or imply that a specific device / component / element must have a specific orientation or be constructed and operated in a specific positional relationship, and therefore cannot be understood as a limitation of the application.

[0029] In addition, if the terms "horizontal", "vertical", "overhanging", "parallel", etc. appear, it does not mean that the corresponding device / component / element must be absolutely horizontal or vertical or overhanging or parallel, but can be slightly inclined or have a deviation. For example, "horizontal" only means that its direction is relatively more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined. Alternatively, it can be simplified to mean that the corresponding device / component / element is arranged in the direction of "horizontal", "vertical", "overhanging", "parallel", etc., and can have an error / deviation of ±10% with respect to the corresponding direction, more preferably an error / deviation of ±8% or less, more preferably an error / deviation of ±6% or less, more preferably an error / deviation of ±5% or less, and more preferably an error / deviation of ±4% or less. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its role in the scheme of the application.

[0030] In addition, the terms "first", "second", "third", etc. appearing in the terms are only used to distinguish the description of the same or similar parts, and should not be understood as emphasizing or implying the relative importance of the specific parts.

[0031] In addition, in the description of the embodiments of the present application, "several" "a plurality of" "several" represents at least 2. It can be 2, 3, 4, 5, 6, 7, 8, 9, etc. Any case, it can even be more than 9 cases.

[0032] In addition, in the description of the technical solutions of the present application, unless otherwise specified / limited / limited, the terms "set", "install", "connect", "connect", "set", "lay", "arrange" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected, which can be welding, riveting, bolting, screwing and other commonly used connection means in the art. The connection can be mechanical connection, electrical connection or communication connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication between two elements.

[0033] Embodiment 1 As shown in Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 , a pump shaft forging forming die comprises a lower die 2, a first extrusion mechanism 3, a second extrusion mechanism 4 and an ejection mechanism 5; The lower die 2 is provided with a forming cavity 21 matched with the shape of the lower part of the pump shaft; The first extrusion mechanism 3 comprises an upper outer die 31 and a punch 32, the upper outer die 31 is arranged at the top of the lower die 2, and the punch 32 is arranged in the inner cavity of the upper outer die 31 and can press the blank downward along the inner cavity of the upper outer die; The second extrusion mechanism 4 comprises a punch upper die, the bottom of the punch upper die is provided with a matching surface matched with the top surface of the lower die 2, and the matching surface is provided with a forming groove 41 for forming the upper part of the pump shaft; The ejection mechanism 5 comprises an ejection rod 51 arranged at the bottom of the lower die 2 for ejecting the formed forging from the forming cavity 21.

[0034] The present application realizes the overall precision forming of the turbine pump shaft with flange and slender rod composite structure through the special structure design of twice extrusion forming, which specifically comprises: First extrusion (rod forming): the blank 6 is pressed into the forming cavity 21 of the lower die 2 by the first extrusion mechanism 3 (upper outer die 31 + punch 32) to form the slender rod part of the pump shaft; Second extrusion (flange forming): the upper part of the blank 6 is extruded by the second extrusion mechanism 4 (punch upper die) to make the metal flow to the forming groove 41 and the area between the punch upper die and the lower die 2, forming the pump shaft flange and the upper part of the pump shaft; Ejection demolding: the final formed forging is ejected from the mold by the ejection mechanism 5 (ejection rod 51).

[0035] In an optional embodiment, the side surface of the forming groove 41 is designed as a conical surface, the angle of the conical surface is 5 degrees, and the large end of the conical surface is arranged towards the lower die 2. The conical surface can guide the material flow to the area between the heading upper die and the lower die 2 during the extrusion process, so as to more easily form the flange part of the pump shaft.

[0036] In one or several embodiments, the forming cavity 21 can include a conical section 211 and a cylindrical section 212, which are sequentially communicated from top to bottom, and the large end of the conical section 211 is arranged away from the cylindrical section 212. The design of the conical section 211 helps to guide the gradual deformation of the blank 6 during the extrusion process, reduces the metal flow resistance, avoids stress concentration, improves the uniformity of metal filling, and the excess material of the forged piece after forming by the conical section 211 can be removed by machining. The cylindrical section 212 ensures the dimensional accuracy and surface finish of the long rod part of the pump shaft.

[0037] In an optional embodiment, the angle of the conical section 211 (the angle between the generatrix and the axis) is designed as 25-35°, which reduces the extrusion resistance during the extrusion process. The blank 6 undergoes three-way compressive stress plastic flow in the conical section 211, the metal fibers continuously extend along the axial direction, and the flow line truncation defect in free forging is eliminated. In an optional embodiment, the upper part of the conical section 211 can be provided with a limiting section 213, and a protrusion is arranged at the bottom of the upper outer die 31 corresponding to the limiting section 213. When the upper outer die 31 is installed, the protrusion at the bottom of the upper outer die 31 is embedded into the limiting section 213 at the upper part of the conical section 211. The cooperation between the limiting section 213 and the protrusion can accurately control the relative position of the upper outer die 31 and the lower die 2, avoid the misalignment of the mold, and ensure the coaxiality and dimensional consistency of the forged piece.

[0038] In an optional embodiment, an extrusion section 214 can be arranged at one end of the cylindrical section 212 connecting the conical section 211. The extrusion section 214, the cylindrical section 212 and the conical section 211 are coaxial, and the diameter of the extrusion section 214 is slightly smaller than that of the cylindrical section 212. The reduced diameter design of the extrusion section 214 causes local deformation of the blank 6 when passing through, reduces the contact area between the blank 6 and the side wall of the mold, thereby significantly reducing the friction resistance, and avoiding the difficulty of filling or surface cracking caused by long-distance friction in traditional constant-diameter molds.

[0039] In an optional embodiment, a correction section 215 can also be arranged at the middle part of the cylindrical section 212. The diameter of the correction section 215 is the same as that of the extrusion section 214. The correction section 215 can fine-tune the diameter of the lower part of the forged piece after extrusion, ensure the perpendicularity and straightness of the long rod part, and reduce the subsequent machining requirements.

[0040] In an optional embodiment, the end of the cylindrical section 212 away from the conical section 211 can be provided with an embedded section 216, which is adapted to the diameter of the upper part of the ejector rod 51, and the ejector rod 51 can enter into the forming cavity 21 by a stroke of the length of the embedded section 216, so as to facilitate the ejector rod 51 to eject the formed blank 6.

[0041] In one or more embodiments, the ejecting mechanism 5 can further include a pad 52, which is arranged at the top of the stepped ejector rod 51, and the diameter of the pad 52 is adapted to the diameter of the cylindrical section 212, and the pad can extend into the cylindrical section 212 under the action of the ejector rod 51 to increase the ejecting length.

[0042] Embodiment 2 As shown in Figure 2 , Figure 3 , Figure 4 and Figure 5 , the present application provides a pump shaft forging forming method, which comprises the following steps: S1, an upper section outer die 31 is arranged at the top of the lower die 2, and the blank 6 is pressed into the forming cavity 21 of the lower die 2 by the punch 32 along the inner cavity of the upper section outer die 31 to form the lower part of the pump shaft; process parameters: material: 30Cr2Ni4MoV, blank 6 heating temperature: 1100±10℃, extrusion speed: 15mm / s, extrusion ratio: 3.2-4.2, deformation mechanism: three-way compressive stress plastic flow occurs in the conical zone of the blank 6, and the metal fibers continuously extend along the axial direction to eliminate the flow line truncation defects in free forging.

[0043] S2, the upper section outer die 31 is removed, and a punch upper die adapted to the shape of the upper part of the pump shaft is connected to the punch 32, and the heated blank 6 is pressed by the punch upper die to flow to the area between the punch upper die and the lower die 2 to form the flange and the upper part of the pump shaft; the forming process: the flange upset forming is completed in a single heating cycle; pressure holding for 2min to eliminate the internal stress generated during forging; S3, the extrusion formed blank is machined according to the final size of the turbine pump shaft.

[0044] In step S1, the upper part of the blank 6 is limited by the upper section outer die 31, and the blank 6 is pressed to the forming cavity 21 of the lower die 2 by the punch 32 to make the forming cavity 21 more compact and improve the forming quality of the lower part of the pump shaft; in step S2, the blank 6 is extruded by the punch upper die, and the blank 6 flows to the area between the punch upper die and the lower die 2 to form the flange part of the pump shaft; the method forms the slender rod part and the flange part of the turbine pump shaft in a step-by-step and zoned manner, realizes the integrated forming of the slender rod and the flange, and reduces the amount of post-processing machining.

[0045] In an optional embodiment, a first heating process is provided before step S1, in which the lower portion of the blank 6 is heated. By heating only the lower portion of the blank 6 (corresponding to the molding area of ​​the lower portion of the pump shaft), it is ensured that the material in this area reaches the optimal plastic deformation temperature (1100±10°C), and the flange and the area above are not heated. This can maintain the rigidity of the upper portion of the blank 6, prevent the contact between the punch 32 and the upper portion of the blank 6 from becoming unstable, and prevent the subsequent upper section outer mold 31 from being difficult to remove.

[0046] In an optional embodiment, a second heating process is provided between steps S1 and S2, in which the upper portion of the blank 6 is heated. By heating only the upper portion of the blank 6 (corresponding to the upper portion of the pump shaft and the forming area of ​​the flange structure), it is ensured that the material in this area reaches the optimal plastic deformation temperature (1100±10°C). The lower area of ​​the pump shaft is not heated, thereby maintaining the rigidity of the lower portion of the blank 6 and preventing deformation of the lower portion of the blank 6 during extrusion. At the same time, the problem of grain growth caused by repeated heating of the upper portion and the lower portion of the blank 6 is avoided.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A pump shaft forging die, characterized in that: It comprises a lower die (2), a first extrusion mechanism (3) and a second extrusion mechanism (4); Lower mold (2): provided with a molding cavity (21) adapted to the shape of the lower portion (13) of the pump shaft; A first extrusion mechanism (3): comprising an upper outer die (31) and a punch (32), wherein the upper outer die (31) is arranged on the top of the lower die (2), and the punch (32) is arranged along the inner cavity of the upper outer die (31); The second extrusion mechanism (4) comprises an upper die on the pier head, wherein the bottom of the upper die is provided with a fitting surface adapted to the top surface of the lower die (2), and the fitting surface is provided with a forming groove (41) for forming the upper part (11) of the pump shaft.

2. A pump shaft forging die according to claim 1, characterized in that: The side wall of the forming groove (41) is configured to be conical, with the large end of the conical surface facing the lower die (2).

3. A pump shaft forging die according to claim 1, characterized in that: The molding cavity (21) comprises a tapered section (211) and a cylindrical section (212) that are connected in sequence, and the cylindrical section (212) is used to mold the long rod portion of the lower part (13) of the pump shaft.

4. A pump shaft forging die according to claim 3, characterized in that: A limiting section (213) is provided on the upper portion of the conical section (211), and a protrusion adapted to the limiting section (213) is provided on the bottom portion of the upper section outer mold (31).

5. A pump shaft forging die according to claim 3, characterized in that: An extrusion section (214) is provided at one end of the cylindrical section (212) connected to the conical section (211), and the diameter of the extrusion section (214) is smaller than the diameter of the cylindrical section (212).

6. A pump shaft forging die according to claim 5, characterized in that: A correction section (215) is provided in the middle of the cylindrical section (212), and the correction section (215) is adapted to the diameter of the extrusion section (214).

7. A pump shaft forging die according to claim 3, characterized in that: An embedded section (216) is provided at one end of the cylindrical section (212) away from the conical section (211), and the embedded section (216) is adapted to the diameter of the upper portion of the ejector rod (51).

8. A method for forging a turbine pump shaft (1), characterized in that: The steps include: S1. An upper outer die (31) is arranged on the top of the lower die (2), and a punch (32) is used to press the blank (6) along the inner cavity of the upper outer die (31), and the blank (6) is pressed into the forming cavity (21) of the lower die (2) to form the lower portion (13) of the pump shaft. S2. Take out the upper outer die (31), connect the pier head upper die that matches the shape of the upper part of the pump shaft (11) to the punch (32), press the blank (6) down through the pier head upper die, and make the blank (6) flow to the area between the pier head die and the lower die (2), thereby forming the flange (12) and the upper part of the pump shaft (11).

9. A method for forging a turbine pump shaft (1) according to claim 8, characterized in that: A first heating process is provided before step S1, in which the lower portion of the blank (6) is heated.

10. A method for forging a turbine pump shaft (1) according to claim 9, characterized in that: A second heating process is provided between steps S1 and S2, in which the upper portion of the blank (6) is heated.

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