Composite die forging process for large wind power gear blank

Abstract

The invention discloses a composite die forging process for a large wind power gear blank. The composite die forging process comprises the following steps: sawing a bar according to process requirements; then, the bar material is heated; then the heated bar is taken out and placed between V-shaped anvils to be slightly pressed and drawn out, and then the bar is placed on a flat anvil to be upset; then the upset bar is inverted and drawn out, the drawn-out bar is upset vertically, and a cake blank is formed; finally, punching the cake blank to form an annular blank, and finishing the outer circle and the height according to the process size; then, the annular blank is heated; and finally, putting the heated annular blank into a die forging die, and carrying out die forging to obtain the required formed forge piece. According to the large wind power gear blank composite die forging process, the composite process of free forging and closed die forging is adopted, materials become more uniform and compact through free forging, and compaction and welding of defect areas and surrounding materials are facilitated; the closed die forging forming efficiency is high, the size and performance consistency of forgings produced in batches is good, batch production of large-size gear blanks is achieved, and the production efficiency is high.

Description

Technical Field

[0001] The invention relates to the field of large wind power gear processing, and in particular to a large wind power gear blank composite die forging process. Background Art

[0002] With the development of larger wind turbines, the specifications of the speed increasing gears in wind turbine gearboxes are getting larger and larger, and the requirements for the quality and manufacturing cost of large gears are also getting higher and higher.

[0003] Due to the limitation of equipment tonnage, the conventional closed die forging process can no longer meet the pressure requirements of large-sized gears, resulting in incomplete forgings, increased heating and back-pressing times, and unqualified gear forgings in size and internal quality.

[0004] Under the above-mentioned conditions, large-sized gears are often produced using free forging technology; however, gears produced using free forging technology have large forging margins, low material utilization, poor surface quality, and are affected by human factors, resulting in poor consistency in product size and performance and low production efficiency, making them unsuitable for mass production. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a composite die forging process for a large wind power gear blank.

[0006] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0007] A composite die forging process for a large wind power gear blank comprises the following steps:

[0008] S1. Cutting: Cut the continuous casting billet into bars of certain specifications and lengths according to the process requirements;

[0009] S2, heating: transfer the bar material into the natural gas heating furnace for heating;

[0010] S3, free forging: take out the heated bar, place it between two symmetrical V-shaped anvils, press and stretch it lightly to reduce its diameter and increase its length; then place the stretched bar between two symmetrical flat anvils and upset it to half of its height, ensuring that the upsetting ratio is ≥2; then pour the upset bar down and stretch it along the center line of the original bar to twice its height, the cross section of the bar is stretched to a circle, and the stretching ratio is about 2; then stand the stretched bar up and place it between two flat upsetting plates and upset it to the required height to form a cake blank; finally, place the upper punch at the center of the top of the cake blank, cooperate with the upsetting plate to punch the cake blank to make it a ring blank and refine the outer circle and height according to the process size;

[0011] S4, hot material return to the furnace: the annular billet is loaded into the natural gas furnace for heating;

[0012] S5. Die forging: The heated ring blank is placed in a die forging die, and then the die forging die is pressed down by a forging press to die forge the ring blank into the desired shaped forging.

[0013] Furthermore, in step S2, the rod material is heated to 850° C. in a natural gas heating furnace and kept warm for 2 hours to allow it to be heated evenly, and then heated to 1220-1250° C. and kept warm for 3-3.5 hours.

[0014] Furthermore, in step S4, the annular blank is heated to 1180° C. in a natural gas heating furnace and kept warm for 2 hours;

[0015] Furthermore, in step S5, the die forging die is composed of an upper die and a lower die, the upper die and the lower die correspond to each other up and down, a lower die cavity is arranged at the top of the lower die, and the bottom of the upper die can be inserted into the lower die cavity; a lower punch fixedly connected to the lower die cavity is arranged at the bottom center of the lower die cavity, the height of the lower punch is higher than the top height of the lower die cavity, and a connecting hole opening downward and plug-matched with the lower punch is arranged at the bottom center of the upper die.

[0016] Furthermore, a vent hole is provided at the center of the top of the connection hole and penetrates upward through the top of the upper mold.

[0017] Furthermore, a spoke upper module having an annular end face and protruding downward is provided at the bottom of the upper die located outside the connecting hole; a spoke lower module having an annular end face and protruding upward is provided at the bottom of the lower die cavity located outside the lower punch, and the spoke upper module and the spoke lower module are symmetrical up and down.

[0018] Compared with the prior art, the advantages of the present invention are as follows: this large-scale wind turbine gear blank composite die forging process adopts a composite process of free forging and closed die forging. In free forging, two upsetting and two drawing processes are performed to make the material more uniform and dense. The central defect of the continuous casting billet bar is subjected to repeated deformation such as stretching and compression, which helps to compact and weld the defective area and surrounding materials, thereby reducing or eliminating the defect. The closed die forging process has high forming efficiency and relies on the guarantee of the mold. The size and performance consistency of mass-produced forgings are good, thus realizing the mass production of large-size gear blanks. At the same time, it can ensure the consistency of the size and performance of the gear forgings and has high production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0020] Figure 1This is a free forging process flow chart of a large wind power gear blank composite die forging process of the present invention;

[0021] Figure 2 It is a schematic diagram of the die forging die structure in a composite die forging process for a large wind power gear blank of the present invention.

[0022] In the figure: 1, bar; 11, blank; 111, ring blank; 12, cake blank; 2, V-shaped anvil; 3, flat anvil; 4, upsetting plate; 5, forging die; 51, upper die; 511, connecting hole; 512, exhaust hole; 513, spoke upper module; 52, lower die; 521, lower die cavity; 522, lower punch; 523, spoke lower module. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but only represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it is not necessary to further define and explain it in the subsequent drawings. In the description of the embodiments of the present invention, it should be noted that if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invention product is usually placed when used, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0025] In addition, the terms "horizontal" and "vertical" do not mean that the components must be absolutely horizontal or vertical, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure or component must be completely horizontal, but can be slightly tilted.

[0026] In the description of the embodiments of the present invention, "plurality" means at least 2.

[0027] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] Example

[0029] The present invention relates to a composite die forging process for large wind turbine gear blanks, which is used for processing large wind turbine gears. The composite die forging process for large wind turbine gear blanks comprises the following steps (see the attached manual for details). Figure 1 shown):

[0030] Step S1, cutting: sawing the continuous casting billet into billets 1 of certain specifications and lengths according to process requirements;

[0031] Step S2, heating: the rod material 1 is transferred into a natural gas heating furnace for heating, heated to 850°C and kept warm for 2 hours to make it heated evenly, and then heated to 1220-1250°C and kept warm for 3-3.5 hours;

[0032] Step S3, free forging: take out the heated bar 1, place it between two symmetrical V-shaped anvils 2, press it lightly and stretch it to reduce its diameter and increase its length; then place the stretched bar 1 between two symmetrical flat anvils 3 and upset it to half of its height, ensuring that the upsetting ratio is ≥2; then pour the upset bar 1 down and stretch it along the center line of the original bar to twice its height, the cross-section of the bar 1 is stretched to a circle, and the stretching ratio is about 2; then stand up the stretched bar 1 and place it between two flat upsetting plates 4 and upset it to the required height to form a cake blank 12; finally, place an upper punch 41 at the center of the top of the cake blank 12, cooperate with the upsetting plate 4 to punch the cake blank 12 to make it a ring-shaped blank 111 and refine the outer circle and height according to the process size. The cake blank 12 reduces the investment of the forging by punching. The shadow area can reduce the forming force required for subsequent closed die forging and reduce the tonnage requirements of the equipment; at the same time, this step makes the blank more uniform and dense through two upsetting and two drawing, and the central defect of the continuous casting blank bar 1 is subjected to repeated deformation such as stretching and compression, which is conducive to the compaction and welding of the defect area and the surrounding materials, and reduces or eliminates the defects; in the process of upsetting and drawing, the main deformation is always along the central axis of the bar 1 or perpendicular to the central axis, so that the size and range of the residual defects in the center of the continuous casting blank bar are reduced, and do not deviate from the central axis, and finally removed by central punching, ensuring that the blank flaw detection meets the requirements; in addition, the repeated upsetting and drawing deformation can break the original large grains, and promote the re-nucleation and recrystallization of the material, so that the grains are refined and uniform, the banded structure of the material is uniform, and the anisotropic mechanical properties of the forging are improved;

[0033] Step S4, hot material return to the furnace: the annular blank 111 is placed in a natural gas furnace for heating, heated to 1180° C. and kept warm for 2 hours; by lowering the heating temperature, the growth rate of the grains inside the material can be slowed down, the abnormal growth of the grains can be suppressed, and the grains can be kept small and uniform;

[0034] Step S5, die forging: the heated annular blank 111 is placed in the die forging die 5, and then the die forging die 5 is pressed down by a forging press to die forge the annular blank 111 into a desired forged part; see the attached manual for Figure 2As shown, the die forging die 5 is composed of an upper die 51 and a lower die 52, the upper die 51 and the lower die 52 correspond to each other up and down, a lower die cavity 521 is arranged on the top of the lower die 52, and the bottom of the upper die 51 can be inserted into the lower die cavity 521; a lower punch 522 fixedly connected to the lower die cavity 521 is arranged at the bottom center of the lower die cavity 521, the height of the lower punch 522 is higher than the top height of the lower die cavity 521, and a connecting hole 511 with a downward opening and plugged with the lower punch 522 is arranged at the bottom center of the upper die 51; during die forging, the ring blank 111 is placed on the outside of the lower punch 522 through the punch hole at the center thereof, which can limit the position of the ring blank 111 in the lower die cavity 521 and realize the centering of the ring blank 111. At the same time, the upper and lower dies can be accurately positioned by the lower punch 522 and the connecting hole 511 that are sleeved together up and down; In order to facilitate the discharge of gas in the lower die cavity 521 during die forging and ensure the smooth progress of die forging and the forging effect, an exhaust hole 512 is arranged at the top center of the connecting hole 511 and penetrates the top of the upper die 51 upward; in order to facilitate the formation of spokes on the upper and lower surfaces of the gear forging, improve the dimensional accuracy of the gear forging and reduce the subsequent processing allowance, the bottom of the upper die 51 located outside the connecting hole 511 is provided with a spoke upper module 513 with an annular end face and protruding downward; the bottom of the lower die cavity 521 located outside the lower punch 522 is provided with a spoke lower module 523 with an annular end face and protruding upward, the spoke upper module 513 and the spoke lower module 523 are symmetrical up and down to ensure the forming effect of the spokes on the upper and lower surfaces of the gear; the closed die forging process has high forming efficiency, relies on the mold guarantee, and has good consistency in size and performance of forgings produced in batches.

[0035] This large-scale wind turbine gear blank composite die forging process adopts a composite process of free forging and closed die forging. In the free forging, two upsetting and two drawing processes are performed to make the material more uniform and dense. The central defect of the continuous casting billet bar 1 is subjected to repeated deformation such as stretching and compression, which helps to compact and weld the defective area and surrounding materials, thereby reducing or eliminating the defect. The closed die forging process has high forming efficiency and relies on the mold guarantee. The size and performance consistency of batch-produced forgings are good, which realizes the batch production of large-size gear blanks, while ensuring the consistency of the size and performance of the gear forgings and high production efficiency.

[0036] It should be emphasized that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A composite die forging process for large wind turbine gear blanks, characterized in that: The following steps are involved: S1, cutting: sawing the continuous casting billet into billets of certain specifications and lengths according to the process requirements (1); S2, heating: transferring the bar material (1) into a natural gas heating furnace for heating; S3, free forging: take out the heated bar (1), place it between two symmetrical V-shaped anvils (2) and gently press and stretch it to reduce its diameter and increase its length; then place the stretched bar (1) between two symmetrical flat anvils (3) and upset it to half of its height, ensuring that the upsetting ratio is ≥2; then turn the upset bar (1) down and stretch it along the center line of the original bar to twice its height, the cross section of the bar (1) is stretched to a circular shape, and the upsetting ratio is about 2; then stand the stretched bar (1) up and place it between two flat upsetting plates (4) and upset it to the required height to form a cake blank (12); finally place an upper punch (41) at the center of the top of the cake blank (12), cooperate with the upsetting plate (4) to punch the cake blank (12) to make it a ring blank (111) and refine the outer circle and height according to the process size; S4, hot material return to the furnace: the annular blank (111) is placed in a natural gas furnace for heating; S5, die forging: the heated annular blank (111) is placed in a die forging die (5), and then the die forging die (5) is pressed down by a forging press to die forge the annular blank (111) into a desired shaped forging.

2. A large-scale wind turbine gear blank composite die forging process according to claim 1, characterized in that: In step S2, the rod material (1) is heated to 850°C in a natural gas heating furnace and kept at this temperature for 2 hours to allow it to be heated evenly, and then heated to 1220-1250°C and kept at this temperature for 3-3.5 hours.

3. The large wind turbine gear blank composite die forging process according to claim 1 is characterized in that: In step S4, the annular blank (111) is heated to 1180° C. in a natural gas heating furnace and kept at this temperature for 2 hours.

4. A large-scale wind turbine gear blank composite die forging process according to claim 1, characterized in that: In step S5, the die forging die (5) is composed of an upper die (51) and a lower die (52), wherein the upper die (51) and the lower die (52) correspond to each other from top to bottom, and a lower die cavity (521) is arranged at the top of the lower die (52), and the bottom of the upper die (51) can be inserted into the lower die cavity (521); a lower punch (522) fixedly connected to the lower die cavity (521) is arranged at the bottom center of the lower die cavity (521), and the height of the lower punch (522) is higher than the top height of the lower die cavity (521); and a connecting hole (511) opening downward and plugging and cooperating with the lower punch (522) is arranged at the bottom center of the upper die (51).

5. A large-scale wind turbine gear blank composite die forging process according to claim 4, characterized in that: A vent hole (512) is arranged at the top center of the connection hole (511) and penetrates upward through the top of the upper mold (51).

6. A large-scale wind turbine gear blank composite die forging process according to claim 4, characterized in that: The bottom of the upper die (51) is provided with a spoke upper module (513) whose end face is annular and protrudes downward at a portion located outside the connecting hole (511); the bottom of the lower die cavity (521) is provided with a spoke lower module (523) whose end face is annular and protrudes upward at a portion located outside the lower punch (522); the spoke upper module (513) and the spoke lower module (523) are symmetrical in upper and lower directions.

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