Balanced shaft bending forming forging die and forging process thereof

Abstract

This application relates to the field of forging equipment technology, specifically disclosing a forging die and forging process for bending and forming a balance shaft. The forging die includes a lower die base, a lower die core, a pre-forging lower die, a limiting component, an adjusting component, and a forging pressing component. The lower die base has a lower die core on its surface, and the lower die core has a lower cavity on its surface. The pre-forging lower die is sleeved on the lower die core, and the edge of the top surface of the pre-forging lower die has a lower groove extending to the side end face. The limiting component is connected to the end face of the pre-forging lower die, and the adjusting component is used to adjust the pre-forging lower die to adapt to the bending and forming stage and the die forging and milling stage. The forging pressing component includes at least a support frame, a pre-forging upper die and an upper die core disposed on the support frame, and the surface of the upper die core has an upper cavity that mates with the lower cavity. The forging process is implemented based on the forging die. This forging die and its process ensure the consistency and stability of the forging dimensions and the smoothness and defects-free corners, while simplifying the process flow and improving the production efficiency and yield of the balance shaft.

Description

Technical Field

[0001] This application relates to the field of forging equipment technology, and in particular to a forging die for bending a balance shaft and its forging process. Background Technology

[0002] For intermediate balance shafts with multiple large-angle bends, taking the "Z"-shaped intermediate balance shaft as an example, the cross-section of the forging varies greatly and is irregular. If the forging is to obtain good structure and properties, the amount of deformation and the uniformity of deformation during forging must be ensured.

[0003] In actual production, the inventors discovered that the difficulties in forging are twofold. First, the billet preparation is difficult. The blank shape after bending needs to match the mold cavity. However, existing forging molds are difficult to guarantee the consistency and stability of the forging dimensions. Large opening angles are prone to occur at the inflection points, which can lead to folding defects during die forging and cause the forging to be scrapped. Second, if the traditional free forging billet preparation method and die milling of the forging are used in the production process, two bending is required, which is difficult. The production process is repeated many times, and it is inconvenient to transfer the forging from the cavity after bending. At the same time, the entire process is complicated, resulting in low production efficiency.

[0004] Therefore, there is an urgent need for a forging die and forging process for intermediate balance shafts with large-angle bending. Summary of the Invention

[0005] This application aims to provide a forging die and forging process for bending balance shafts, so as to at least solve the technical problems of complex process, low production efficiency and low product yield in the forging process of intermediate balance shafts with multiple large-angle bends in the prior art.

[0006] In a first aspect, embodiments of this application provide a forging die for bending and forming a balance shaft, comprising:

[0007] A lower mold base, wherein a lower mold core is provided on the top surface of the lower mold base along a first direction, and a lower mold cavity is provided on the surface of the lower mold core opposite to the surface of the lower mold base;

[0008] A pre-forging lower die is fitted onto the lower die core. The edge of the top surface of the pre-forging lower die is provided with a lower groove extending to the side end face. The lower groove is configured for partial contour forging of the balance shaft.

[0009] A limiting assembly is rotatably connected to the side end face of the pre-forging lower die near the lower mold groove. The limiting assembly includes a rotating shaft rotatably connected to the pre-forging lower die and at least one roller connected to one end of the rotating shaft and extending to the lower mold groove. The roller is configured for limiting and fixing during the bending forming process of the balance shaft.

[0010] The adjustment assembly includes a telescopic member disposed on the bottom surface of the lower die base and a sliding frame disposed on the top surface of the lower die base and connected to the output end of the telescopic member; the sliding frame is used to adjust the height position of the pre-forging lower die in the first direction so that the pre-forging lower die can be adapted to the bending forming stage and the die forging and milling stage in the forging process of the balance shaft.

[0011] The forging assembly includes a support frame mounted on the lower die base, a drive motor mounted on the support frame, a heavy-duty lead screw connected to the drive motor, and a pre-forging upper die mounted on the end of the heavy-duty lead screw away from the drive motor. The pre-forging upper die has an upper groove extending to the side end face at the bottom surface edge facing the pre-forging lower die. The upper groove and the lower groove cooperate to form a cavity for bending the balance shaft. An upper die core is connected inside the pre-forging upper die, and the bottom surface of the upper die core has an upper cavity that cooperates with the lower cavity.

[0012] Wherein, the first direction is the height direction of the lower mold base, and the second direction is the width direction of the lower mold base.

[0013] In some embodiments, the lower pre-forging die and the upper pre-forging die are disposed opposite to each other in the first direction, the die surfaces of the lower groove and the upper groove are at least partially constructed as curved surfaces, and the shapes of the two die surfaces are complementary. During the bending forming stage, the lower groove and the upper groove are closed to form the bending cavity of the balance shaft.

[0014] In some embodiments, a pressure-resistant area is provided on the side end of the lower groove. The limiting assembly further includes a torsion spring sleeved on the rotating shaft and a limiting rod connected to one end of the rotating shaft and forming an angle with the roller. The torsion spring is used to reset the rotating shaft after rotation. The end of the limiting rod away from the rotating shaft extends to the pressure-resistant area to limit the end of the balance shaft. When the upper groove presses down toward the lower groove to abut the limiting rod, the limiting rod rotates within the pressure-resistant area.

[0015] In some embodiments, the lower pre-forging die has a first guide cavity extending through it along the first direction, and the lower die core passes through the first guide cavity and is slidably connected to the lower pre-forging die; the upper pre-forging die has a second guide cavity extending through it along the first direction, and the upper die core passes through the second guide cavity and is selectively slidably connected to the upper pre-forging die.

[0016] In some embodiments, the support frame is provided with limiting plates arranged along the first direction on opposite sides of the pre-forging upper die. The pre-forging upper die is slidably connected to a locking block with one end abutting the surface of the limiting plate on both sides near the limiting plate. The upper die core side end is provided with a locking groove that cooperates with the locking block. The limiting plate is configured to change the connection mode between the pre-forging upper die and the lower die core through the locking block, so that the pre-forging upper die can adapt to the bending and forming stage and the die forging and milling stage in the forging process of the balance shaft.

[0017] In some embodiments, the limiting plate is provided with a bent portion and a first limiting portion and a second limiting portion located at the upper and lower ends of the bent portion, wherein the distance between the two first limiting portions is less than the distance between the two second limiting portions, when the locking block is located at the first limiting portion, one end of the locking block extends into the locking groove to fix the pre-forging upper die and the upper die core, and when the locking block is located at the second limiting portion, one end of the locking block is located outside the locking groove to slide the pre-forging upper die and the upper die core.

[0018] In some embodiments, the sliding frame includes a frame body and a crossbar disposed at one end of the frame body near the limiting plate, wherein the crossbar is used to adjust the position of the limiting plate in the first direction, and the bottom surface of the pre-forging lower die is provided with a pulley group that contacts a portion of the surface of the frame body, and the frame body is used to adjust the position of the pre-forging lower die in the first direction.

[0019] In some embodiments, the surface of the lower die base is provided with a plurality of sleeves spaced around the lower die core, and the bottom surface of the pre-forging lower die is provided with a plurality of guide rods extending into the sleeves. The sleeves are used for guiding and limiting the pre-forging lower die when it slides in the first direction.

[0020] In some embodiments, the bottom surface of the pre-forging die is provided with a through hole extending to the lower mold groove along the first direction. A slide rod is slidably connected in the through hole. A reset elastic element is coaxially sleeved on the part of the slide rod facing away from the lower mold groove. The sliding frame is provided with a push rod arranged along the second direction. When the sliding frame slides along the second direction, the push rod at least partially abuts against one end of the slide rod, so that the other end of the slide rod extends into the lower mold groove.

[0021] Compared with the prior art, the technical solution provided in the first aspect of this application has at least the following beneficial effects or advantages:

[0022] By setting a lower groove penetrating the side end face at the edge of the pre-forging lower die, and setting an upper groove penetrating the side end face and adapted to the lower groove at the edge of the pre-forging upper die, the lower groove and the upper groove cooperate to form a bending profile forging cavity with a balance shaft. Furthermore, by setting a limiting component, including a roller extending near the lower groove, the limiting component can fix and limit the pre-forging when the pre-forging part with a rough shape is placed in the lower groove. Simultaneously, during the bending forming forging process, the limiting component synchronously limits the pre-forging, thus ensuring the accuracy of the pre-forging part's position during the forging process, thereby improving the consistency and stability of the forging dimensions. The design of the lower and upper grooves allows for one-time bending and forming, ensuring the deformation amount and uniformity during forging. Furthermore, after bending and forging, it facilitates the removal of the bent forging from the lower groove. The sliding frame allows adjustment of the relative positions of the limiting plate, the pre-forging die, and the lower die core, enabling the forging die to switch from the bending stage to the die forging and milling stage. The bent forging is then placed in the lower cavity of the lower die core for secondary forging to form the balance shaft forging. Thus, the forging production of the bent balance shaft is completed on a single forging die machine, simplifying the process and improving the production efficiency of the balance shaft.

[0023] Secondly, this application provides a forging process for bending and forming a balance shaft, wherein the forging process is implemented based on the forging die for bending and forming the balance shaft described in the first aspect above, and the forging process includes:

[0024] The raw materials are deburred and pretreated, then heated and then forged into billets using conventional methods to obtain pre-forged parts with rough shapes.

[0025] The cooled pre-forging part is reheated, and the upper groove of the pre-forging upper die and the lower groove of the pre-forging lower die are preheated. The position of the pre-forging lower die and the limiting plate is adjusted so that the forging die is in the first forging state, which is adapted to the bending forming stage.

[0026] The heated initial forging is placed in the lower mold groove and fixed by the limiting component. The drive motor is controlled to move the pre-forging upper mold toward the pre-forging lower mold. The pre-forging is bent and then forged using the upper mold groove and the lower mold groove to form a bent forging.

[0027] The bent forging is removed and the hot material is reheated in the furnace. The upper cavity of the upper die core and the lower cavity of the lower die core are preheated. The position of the pre-forging lower die and the limiting plate is adjusted so that the forging die is in the second forging state. The second forging state is adapted to the forging milling stage.

[0028] The heated bending forging is placed in the preheated lower cavity, and the drive motor is controlled to move the upper die core toward the lower die core. The bending forging is then subjected to secondary die forging using the upper and lower cavities to form a balance shaft forging.

[0029] Compared with the prior art, the technical solution provided in the second aspect of this application has at least the following beneficial effects or advantages:

[0030] In the forging process of this application, before the bending and forming primary die forging, a pre-forging part with a rough shape at the corresponding position is obtained through conventional forging billet. The rough shape of the pre-forging part corresponds to the turning point of the formed balance shaft and the die faces of the upper and lower grooves. Then, the bending and forming primary die forging is carried out through the upper and lower pre-forging dies to avoid the appearance of open corners at the turning points, ensuring the consistency and stability of the forging dimensions and the smoothness and defects of the corners. Then, by adjusting the die forging state of the forging die, the bent die forging part is placed in the cavity of the lower die core for secondary die forging to form the balance shaft forging. This forging process has a simple process flow and improves the production efficiency and yield of the balance shaft.

[0031] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the structure of a forging die according to an embodiment of this application;

[0034] Figure 2 This is a partial cross-sectional structural diagram of a forging die according to an embodiment of this application;

[0035] Figure 3 This is a schematic diagram of the internal structure of a forging die according to an embodiment of this application;

[0036] Figure 4 This is another structural schematic diagram of a forging die after partial cross-section according to an embodiment of this application;

[0037] Figure 5 This is a schematic diagram of the structure of the pre-forging lower die and the lower die core after assembly according to an embodiment of this application;

[0038] Figure 6 This is a schematic diagram of the structure of the limiting component according to an embodiment of this application;

[0039] Figure 7 This is a schematic diagram of the lower mold core and adjustment assembly according to an embodiment of this application;

[0040] Figure 8 This is a schematic diagram of the structure of the pre-forging upper die and upper die core according to an embodiment of this application;

[0041] Figure 9 This is another structural schematic diagram of a forging die after partial cross-section according to an embodiment of this application;

[0042] Figure 10 This is a flowchart of the forging process according to an embodiment of this application;

[0043] Figure 11 This is a schematic diagram of the raw material preparation process for the balance shaft according to an embodiment of this application;

[0044] Figure 12 This is a schematic diagram of the balance shaft placed in the pre-forging lower die according to an embodiment of this application;

[0045] Figure 13 This is a temperature-time line graph of the heating process in the blank-making step according to an embodiment of this application;

[0046] Figure 14 This is a temperature-time graph of the bending forming and forging heating process according to an embodiment of this application.

[0047] Figure 15 This is a temperature-time line graph of the secondary forging heating process according to an embodiment of this application.

[0048] Figure label:

[0049] 10. Forging dies;

[0050] 100. Lower mold base; 110. Lower mold core; 111. Lower cavity; 112. Clearance hole; 120. Sleeve;

[0051] 200. Pre-forging lower die; 210. Lower groove; 211. Anti-pressure area; 212. Through hole; 230. Pulley block; 240. First guide slide cavity; 241. First annular groove; 250. Slide rod; 251. Reset elastic element; 252. Connecting rod;

[0052] 300, Limiting assembly; 310, Rotating shaft; 320, Torsion spring; 330, Roller; 340, Limiting rod;

[0053] 400. Adjustment component; 410. Telescopic component; 420. Sliding frame; 421. Frame body; 422. Crossbar; 4211. First support surface; 4212. Second support surface; 430. Push rod;

[0054] 500. Forging assembly; 510. Support frame; 511. Side plate; 512. Support plate; 5121. Sliding sleeve; 513. Slide rail; 520. Drive motor; 521. Drive gear; 530. Heavy-duty lead screw; 531. Driven gear; 540. Upper die base; 550. Pre-forging upper die; 551. Upper groove; 552. Second guide cavity; 5521. Second annular groove; 553. Locking block; 554. Return spring; 560. Upper die core; 561. Upper cavity; 562. Locking groove; 570. Limiting plate; 571. Bending part; 572. First limiting part; 573. Second limiting part; 574. Inclined groove;

[0055] A. First direction; B. Second direction; C. Third direction. Detailed Implementation

[0056] The embodiments of this application are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. It should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application.

[0057] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0059] Please see Figures 1 to 4This embodiment provides a forging die 10 for bending a balance shaft. The forging die 10 includes a lower die base 110, a pre-forging lower die 200, a limiting component 300, an adjusting component 400, and a forging component 500. A lower die core 110 is provided on the top surface of the lower die base 110. The pre-forging lower die 200 is sleeved on the lower die core 110 and can move along the height direction of the lower die core 110. A lower groove 551 extending to the side end face is provided on the edge of the top surface of the pre-forging lower die 200. The lower groove 551 is configured for partial contour forging of the balance shaft. The limiting component 300 is rotatably connected to the side end face of the pre-forging lower die 200 near the lower groove 551. The limiting component 300 is configured for limiting and fixing during the bending forging process of the balance shaft. The adjusting component 400 includes a telescopic member 410 provided on the bottom surface of the lower die base 110 and a telescopic member 410 provided on the lower die base 110. A sliding frame 420 is connected to the top surface and the output end of the telescopic member 410; the sliding frame 420 is configured to adjust the height position of the pre-forging lower die 200 so that the pre-forging lower die 200 is adapted to the bending forming stage and the die forging milling stage in the balance shaft forging process; the forging assembly 500 includes a support frame 510 disposed on the lower die base 110, a drive motor 520 disposed on the support frame 510, a heavy-duty lead screw 530 that is drivenly connected to the drive motor 520, and a pre-forging upper die 550 disposed on the end of the heavy-duty lead screw 530 away from the drive motor 520. The pre-forging upper die 550 is provided with an upper groove 210 extending to the side end face at the bottom surface edge of the pre-forging lower die 200. The upper groove 210 and the lower groove 551 cooperate to form a cavity for bending forming of the balance shaft, and an upper die core 560 is connected inside the pre-forging upper die 550. The upper die core 560 and the lower die core 110 cooperate for secondary die forging.

[0060] The technical solution provided in this embodiment involves setting a lower groove 551 penetrating the side end face at the edge of the pre-forging lower die 200, and setting an upper groove 210 penetrating the side end face and adapted to the lower groove 551 at the edge of the pre-forging upper die 550. The lower groove 551 and the upper groove 210 cooperate to form a bending profile forging cavity with a balance shaft. Then, by setting a limiting component 300, which includes a roller 330 extending close to the lower groove 551, when the pre-forging part with a rough shape is placed in the lower groove 551, the limiting component 300 can fix and limit the pre-forging part. At the same time, during the bending forming forging process, the limiting component 300 simultaneously limits the pre-forging part. In this way, the position accuracy of the pre-forging part during the forging process is ensured, thereby improving the consistency and stability of the forging size.

[0061] Furthermore, by setting the lower groove 551 and the upper groove 210, on the one hand, the pre-forged part can be bent into shape in one go, and the deformation amount and deformation uniformity of the forging part during the forging process can be ensured. On the other hand, after bending and forming forging, since the lower groove 551 and the upper groove 210 are preset to penetrate to the side end face, it is convenient to take the bent forging part out of the lower groove 551, and then place the bent forging part into the cavity of the lower die core 110 for secondary forging to form the balance shaft forging part. In this way, the forging production of the bent balance shaft is completed in one forging die 10 equipment, which simplifies the process flow and improves the production efficiency of the balance shaft.

[0062] In some embodiments, for the convenience of describing the various structures of the forging die 10, the height direction of the forging die 10 is defined as the first direction A, the width direction of the forging die 10 is defined as the second direction B, and the length direction of the forging die 10 is defined as the third direction C. One end of the lower die core 110 is fixedly connected to the top surface of the lower die base 110 and is arranged along the first direction A. It should be noted that the projected outline shape of the lower die core 110 along the first direction A can be designed with reference to the outer outline of the finished forging. The pre-forging lower die 200 is fitted on the lower die core 110 and can be adjusted along the height direction of the lower die core 110. This arrangement allows the forging die 10 to perform bending forming and die forging milling processes on the forging.

[0063] In some embodiments, combined with Figure 3 and Figure 4 The support frame 510 may include a side plate 511 connected at one end to the lower die base 110 and a support plate 512 connected at the end of the side plate 511 away from the lower die base 110. The support plate 512 may be parallel to the top surface of the lower die base 110, and a forging space area may be formed between the support plate 512 and the top of the lower die base 110. A slide rail 513 is provided on the side plate 511 near the surface of the pre-forging upper die 550. At the same time, a side surface of the pre-forging upper die 550 is provided with a part that cooperates with the slide rail 513. When the upper pre-forging die 550 slides in the first direction A, the sliding rail 513 and the slider are set to ensure the stability of the upper pre-forging die 550 during the pressing and lifting process. The lower pre-forging die 200 is set opposite to the upper pre-forging die 550 in the first direction A. The die surfaces of the lower groove 551 and the upper groove 210 are at least partially constructed as curved surfaces, and the shapes of the two die surfaces are complementary. During the bending forming stage, the lower groove 551 and the upper groove 210 close the die to form a bending die cavity with a balance shaft.

[0064] Optionally, the drive motor 520 is fixedly mounted on the support plate 512, and the output shaft of the drive motor 520 is provided with a drive gear 521. At the same time, the support plate 512 is rotatably connected to a driven gear that meshes with the drive gear 521. The driven gear 531 is provided with a threaded hole along the central axis and is sleeved on the surface of the heavy-duty lead screw 530 through the threaded hole. When the drive motor 520 runs, the drive gear 521 and the driven gear 531 drive the heavy-duty lead screw 530 to move up and down along the first direction A, thereby driving the pre-forging upper die 550 to perform pressure forging. It should be understood that the specific structure of the transmission method between the heavy-duty lead screw 530 and the driven gear 531, which converts rotation into vertical movement, can be obtained from the prior art. For example, the transmission method of the lead screw and ball nut seat can be referred to.

[0065] Please see Figure 5 and Figure 8 A first guide cavity 240 is provided through the lower pre-forging die 200 along the first direction A. The lower die core 110 passes through the first guide cavity 240 and is slidably connected to the lower pre-forging die 200. A second guide cavity 552 is provided through the upper pre-forging die 550 along the first direction A. The upper die core 560 passes through the second guide cavity 552 and is selectively slidably connected to the upper pre-forging die 550. A first annular groove 241 is provided on the top surface of the lower pre-forging die 200 near the contour edge of the first guide cavity 240, and a second annular groove 241 is provided on the bottom surface of the upper pre-forging die 550 near the contour edge of the second guide cavity 552. The annular groove 5521, the bottom surface of the lower die core 110 is provided with a lower cavity 111, and the bottom surface of the upper die core 560 is provided with an upper cavity 561. The shapes of the lower cavity 111 and the upper cavity 561 can be designed according to the shape of the balance shaft. When the lower cavity 111 and the upper cavity 561 are closed, they form a closed balance shaft cavity. For the secondary die forging process, preliminary milling of the forging can be achieved. The first annular groove 241 and the second annular groove 5521 can be used to temporarily store the burr material, which can reduce the workload of the subsequent milling process and improve the production efficiency of the balance shaft.

[0066] Please see Figure 5 and Figure 6The limiting component 300 is rotatably connected to the side end face of the pre-forging lower die 200 near the lower groove 551. The limiting component 300 includes a rotating shaft 310 rotatably connected to the pre-forging lower die 200, and at least one roller 330 connected to one end of the rotating shaft 310 and extending to the side end face near the lower groove 551. The roller 330 is configured to limit and fix the balance shaft during the bending forming process. The lower groove 551 extends to the side end face and has a pressure-resistant area 211 at the right end along the third direction C. The limiting component 300 also includes a torsion spring 320 sleeved on the rotating shaft 310 and a limiting rod 340 connected to one end of the rotating shaft 310 and forming an angle with the roller 330. The torsion spring 320 is used to reset the rotating shaft 310 after rotation. The end of the limiting rod 340 away from the rotating shaft 310 extends to the pressure-resistant area 211 to limit the end of the balance shaft.

[0067] It should be noted that when the upper groove 210 is pressed down towards the lower groove 551 to abut against the limiting rod 340, the limiting rod 340 rotates within the anti-pressure area 211. At the same time, during this process, the end of the limiting rod 340 always abuts against the end of the pre-forging part. In conjunction with the rollers, the side of the pre-forging part is limited and fixed, thereby further ensuring sufficient and uniform deformation of the forging part during the die forging process and improving the yield of the pre-forging part.

[0068] In some embodiments, to ensure the stability of the pre-forging lower die 200 during the lifting process, a plurality of sleeves 120 spaced around the lower die core 110 are provided on the surface of the lower die base 110. A plurality of guide rods extending into the sleeves 120 are provided on the bottom surface of the pre-forging lower die 200. The sleeves 120 are used for guiding and limiting the pre-forging lower die 200 when it slides in the first direction A. For example, a set of sleeves 120 is provided on each side of the lower die core 110, and two sleeves can be provided in each set, depending on actual needs. The telescopic member 410... The extension direction of the outlet is set along the first direction A. The extension component 410 can be one of a cylinder, an electric push rod, or a hydraulic cylinder, depending on the actual needs. The output end of the extension component 410 is connected to the sliding frame 420. The sliding frame 420 is set on the surface of the lower mold base 110. The sliding frame 420 is distributed on the inner side of the support structure on both sides of the lower mold core 110 and can abut against the two sides of the side plate 511 or the two sleeves 120 distributed along the third direction C. In this way, the guiding and limiting function of the sliding frame 420 is ensured when it slides.

[0069] Please see Figure 5 and Figure 7The sliding frame 420 includes a frame body 421 and a crossbar 422 disposed at the front end of the frame body 421. The crossbar 422 is distributed along the third direction C. The frame body 421 can be composed of two parallel support structure frames spaced apart. The frame body 421 is provided with an upwardly inclined first support surface 4211 and a horizontally arranged second support surface 4212 connected to the first support surface 4211. Meanwhile, multiple sets of pulley groups 230 are provided on both sides of the bottom surface of the pre-forging lower die 200. The pulley group 230 close to the frame body 421 abuts against the first support surface 4211. When the sliding frame 420 slides along the second direction B, the pulley group 230 can slide along the first support surface 4211 to the second support surface 4212, thereby allowing the pre-forging lower die 200 to slide in the first direction A to achieve height position adjustment, so as to meet the bending forming stage and the die forging milling stage.

[0070] In some embodiments, the corners of the upper groove 210 and the lower groove 551 are rounded. A through hole 212 extending to the lower groove 551 is provided on the bottom surface of the pre-forging lower die 200 along the first direction A. The position where the through hole 212 connects to the lower groove 551 can be the lowest point (i.e., the corner) of the lower groove 551. A slide rod 250 is slidably connected in the through hole 212. A reset elastic element 251 is coaxially sleeved on the part of the slide rod 250 facing away from the lower groove 551. The reset elastic element 251 can be one of the elastic structures such as a spring or a shape memory alloy. The sliding frame 420 is provided with a push rod 430 arranged along the second direction B. When the sliding frame 420 slides along the second direction B, the push rod 430 at least partially abuts against one end of the slide rod 250 so that the other end of the slide rod 250 extends into the lower groove 551.

[0071] Specifically, two slide rods 250 can be spaced apart. The ends of the two slide rods 250 facing away from the lower mold groove 551 are connected and fixed by a connecting rod 252. One end of the reset elastic element 251 is connected to the bottom surface of the pre-forging lower die 200, and the other end is connected to the connecting rod 252. The lower die core 110 has a clearance hole 112 along the second direction B. One end of the push rod 430 passes through the clearance hole 112 and has an upward protrusion. This protrusion can be used to move the slide rod 250 upward and lift it when it contacts the connecting rod 252. During the bending forming stage, the sliding frame 42... 0 is located behind the slide bar 250. At this time, the end of the push rod 430 with the protrusion does not touch the connecting rod 252. After one forging in the bending stage is completed, the sliding frame 420 needs to slide forward because it is necessary to adjust the state of the forging die 10 (i.e., in the forging milling stage). This drives the push rod 430 to squeeze the connecting rod 252, so that the slide bar 250 moves into the lower groove 551 along the through hole 212, thereby pushing the bent forging out of the lower groove 551. This facilitates the transfer of the forging after bending.

[0072] Please see Figure 8 and Figure 9 The support frame 510 has limiting plates 570 arranged along the first direction A on opposite sides of the pre-forging upper die 550. The pre-forging upper die 550 has a locking block 553 slidably connected to both sides near the limiting plates 570, with one end abutting the surface of the limiting plate 570. The upper die core 560 has a locking groove 562 on its side end that mates with the locking block 553. The limiting plate 570 is configured to change the connection method between the pre-forging upper die 550 and the lower die core 110 via the locking block 553, allowing the pre-forging upper die 550 to adapt to the bending and forming stage and the die forging and milling stage in the balance shaft forging process. 570 is provided with a bending portion 571 and a first limiting portion 572 and a second limiting portion 573 located at the upper and lower ends of the bending portion 571. The distance between the two first limiting portions 572 is less than the distance between the two second limiting portions 573. When the locking block 553 is located in the first limiting portion 572, one end of the locking block 553 extends into the locking groove 562 to fix the pre-forging upper die 550 and the upper die core 560. When the locking block 553 is located in the second limiting portion 573, one end of the locking block 553 is located outside the locking groove 562 to allow the pre-forging upper die 550 and the upper die core 560 to slide.

[0073] In order to achieve the reset during the movement of the locking block 553, a reset spring 554 arranged in the same direction as the locking block 553 can be set in the pre-forging upper die 550. The reset spring 554 can always be in a compressed state. By setting the reset spring 554, it can be ensured that when one end of the locking block 553 extends into the locking groove 562 and slides to the second limiting part 573, one end of the locking block 553 will exit from the locking groove 562.

[0074] In some embodiments, a sliding sleeve 5121 is provided on the bottom surface of the support plate 512, the top end of the limiting plate 570 extends into the sliding sleeve 5121, and a sloping groove 574 is provided at the bottom of the second limiting part 573. The sloping groove 574 can be a through groove or a blind groove. The push rod 430 extends into the sloping groove 574. Specifically, when the sliding frame 420 is pushed forward along the second direction B, the push rod 430 can slide out from the sloping groove 574. At this time, the limiting plate 570 slides down along the first direction A. At the same time, the sliding frame 420 provides an upward force to the pre-forging lower die 200, causing the pre-forging lower die 200 to slide upward, thereby adjusting the forging die 10 to the secondary forging (forging milling stage) state, that is, the turning part of the limiting plate 570 moves down. In the forging milling stage, the pre-forging upper die 550 and the upper die core 560 always remain fixedly connected.

[0075] Optionally, after the final forging of the die forging and milling stage is completed, when the sliding frame 420 is pushed backward along the second direction B, the push rod 430 can slide into the opening of the inclined groove 574 and provide an upward thrust to the limiting plate 570, thereby causing the limiting plate 570 to move upward. At the same time, the pre-forging lower die 200 slides downward, thereby adjusting the forging die 10 to the state of one-time die forging (bending forming stage), that is, the turning part of the limiting plate 570 moves upward. In the bending forming stage, when the upper die core 560 contacts the lower die core 110, the locking block 553 just passes through the bending part 571, thereby causing the locking block 553 to move towards the second limiting part 573. The upper die core 560 and the pre-forging upper die 550 switch from a fixed connection to a sliding connection, thereby facilitating the bending forming of the forging by the pre-forging upper die 550 and the pre-forging lower die 200.

[0076] Please see Figure 10 This application provides a forging process for bending and forming a balance shaft. This forging process is implemented based on the forging die described in the above embodiments, and includes the following steps:

[0077] Step S100: Deburr the raw material, heat the pretreated raw material, and then perform conventional forging on the heated raw material to obtain a pre-forged part with a rough shape.

[0078] Step S200: The cooled pre-forging part is reheated, and the upper groove of the pre-forging upper die and the lower groove of the pre-forging lower die are preheated. The position of the pre-forging lower die and the limiting plate is adjusted based on the adjustment component so that the forging die is in the first forging state. The first forging state is adapted to the bending forming stage.

[0079] Step S300: Place the heated initial forging in the lower die groove and fix it by limiting components. Control the drive motor to move the upper pre-forging die toward the lower pre-forging die. Use the upper and lower die grooves to bend and then forge the pre-forging to form a bent forging.

[0080] Step S400: Remove the bent forging and reheat the hot material in the furnace, preheat the upper cavity of the upper die core and the lower cavity of the lower die core, and adjust the position of the pre-forging lower die and the limiting plate based on the adjustment component so that the forging die is in the second forging state. The second forging state is adapted to the die forging milling stage.

[0081] Step S500: Place the heated bending forging into the preheated lower cavity, control the drive motor to move the upper die core toward the lower die core, and use the upper and lower cavities to perform secondary die forging on the bending forging to form a balance shaft forging.

[0082] Compared with the prior art, the technical solutions provided by the above embodiments of this application have at least the following beneficial effects or advantages:

[0083] In the forging process described above, before the bending and forming primary die forging, a pre-forged part with a rough shape at the corresponding position is obtained through conventional forging blank. The rough shape of the pre-forged part corresponds to the turning point of the formed balance shaft and the die faces of the upper and lower grooves. The bending and forming primary die forging through the upper and lower pre-forging dies avoids the occurrence of open corners at the turning points, ensuring the consistency and stability of the forging dimensions and the smoothness and defects of the corners. Then, by adjusting the die forging state of the forging die, the bent die forging part is placed in the cavity of the lower die core for secondary die forging to form the balance shaft forging. This forging process has a simple process flow and improves the production efficiency and yield of the balance shaft.

[0084] Please see Figures 11 to 15 This embodiment provides a specific implementation of the forging process for bending and forming the balance shaft based on the above embodiment. For the intermediate balance shaft, the forging material can be TC18 titanium alloy. TC18 titanium alloy is a highly alloyed, high-strength near-β type titanium alloy with a phase transformation temperature T. β The temperature range is 840–880℃. This alloy has good hot workability, weldability, hardenability, and heat-treatable strengthening properties. Its strength after annealing is comparable to that of TC4 and TC6 alloys in the solution-aged state, with values ​​exceeding 1080 MPa. It is the titanium alloy with the highest strength in the annealed state. Therefore, TC18 titanium alloy is often used to manufacture large load-bearing structural components.

[0085] The TC18 titanium alloy balance shaft forgings can be produced using a two-phase zone heating process followed by quasi-β forging at β+15℃. Specifically, the two-phase zone heating temperature is Tβ-35℃, and the quasi-β forging temperature is Tβ+15℃. The heating coefficient in the two-phase zone is 0.8 mm / min, and the heating coefficient in the high-temperature zone of the quasi-β forging is 0.3 mm / min. The overall deformation after each forging process is 30%-40%, and the forging is cooled by diffuse air cooling, resulting in good physical and chemical properties.

[0086] From the forging's shape, it is Z-shaped with two corners of different sizes. One corner has a symmetrical high platform. The forging is a planar parting mold. The forging weighs 26.5 kg, with a maximum outline size of 740×348×126 mm. The shape complexity coefficient is calculated to be 0.18, which is considered relatively complex. Straightening the Z-shaped forging, the forging structure was sectioned and cross-sectional change curves were plotted. The forging shows an overall upward trend along the longitudinal section, with two high inflection points. The cross-section of the forging varies greatly and is irregular. The two bending corners of the forging are approximately obtuse angles of 101 degrees, close to right angles. This structure poses a significant challenge to subsequent billet preparation. To achieve good microstructure and properties, the deformation amount and uniformity during forging must be ensured, and the number of forging passes should be minimized. The main difficulty in forging lies in the billet preparation; the bent blank shape needs to match the mold cavity.

[0087] It should be noted that, to ensure the uniformity and precision of heating, the heating equipment for heating titanium alloy bars needs to be a high-temperature electric furnace of Class III or above (Class II). The heating coefficient for conventional forging billets and die forging is calculated as 0.8 min / mm, and the heating coefficient for the high-temperature zone of quasi-β forging is calculated as 0.3 min / mm; the heating temperature for conventional forging is Tβ-35℃, the heating temperature for the low-temperature zone of quasi-β forging is Tβ-35℃, and the heating temperature for the high-temperature zone of quasi-β forging is Tβ+15℃; the final forging temperature is controlled at ≥720℃, and the cooling method is diffuse air cooling.

[0088] like Figure 11 and Figure 13 As shown, during the billet preparation process, (1) heating equipment: high temperature resistance furnace; (2) heating temperature: Tβ-35℃; (3) holding time: 115min, the longest holding time is 180min; (4) forging equipment: 1000T fast forging, initial forging temperature: Tβ-35℃; final forging temperature: ≥720℃; cooling method: diffused air cooling. (5) The billet preparation process is to first draw one end of the bar stock, and then make a smooth transition at the position of the diameter change, and then draw the other end of the bar stock to form a rough shape on the bar stock.

[0089] like Figure 12 and Figure 14 As shown, during the bending and forming stage, the bar stock with the rough shape is placed in the lower mold groove and fixed in a limited position. (1) Heating equipment: high temperature resistance furnace; (2) Heating temperature: Tβ-35℃; (3) Holding time: 100min, the longest holding time is 150min; (4) Forging equipment: the forging mold in the above embodiment, initial forging temperature: Tβ-35℃; final forging temperature: ≥720℃; cooling method: diffused air cooling. (5) Forging requirements: 1. Before forging, the mold is fully preheated, the preheating temperature is 400℃ and the time is ≥6h; 2. The rough shape is bent first and then die forged, and the underpressure is retained by more than 35mm after die forging; 3. The material placement diagram is as follows. Figure 12 .

[0090] like Figure 12 and Figure 15 As shown, during the die forging and milling stage, (1) heating equipment: high-temperature resistance furnace; (2) heating temperature and holding time are shown in the figure. Figure 15 (3) Forging equipment: the forging mold in the above embodiment, initial forging temperature: Tβ+15℃; final forging temperature: ≥720℃; cooling method: air cooling, (4) Forging requirements: 1. Before forging, the mold should be fully preheated, the preheating temperature is 400℃ and the time is ≥6h; 2. Insulation cotton should be placed in the upper and lower mold cavities; 3. The forging part should be placed into the mold cavity and forged to the tolerance size;

[0091] Furthermore, the forgings after final forging undergo heat treatment using a double annealing process. The first annealing temperature is 840℃, with a holding time of 180 min, followed by furnace cooling at a rate greater than 30℃ / H to 750℃, then holding for another 150 min. The cooling method is to air-cool the parts to room temperature by turning them over. The second annealing temperature is 605℃, with a holding time of 360 min, and the cooling method is to air-cool the parts to room temperature by turning them over.

[0092] The entire process can be simplified as follows: raw material inspection upon arrival → blanking → heating → conventional forging simple billet preparation → shot blasting → grinding → spraying → heating → conventional forging bending → hot material return to furnace for heating → quasi-β forging → edge milling → heat treatment → physical and chemical testing → shot blasting → ultrasonic flaw detection → warehousing.

[0093] In the forging process of this embodiment, before the bending and forming primary die forging, a pre-forging part with a rough shape at the corresponding position is obtained through conventional forging billet. The rough shape of the pre-forging part corresponds to the turning point of the formed balance shaft and the die face of the upper and lower grooves. The bending and forming primary die forging through the upper and lower pre-forging dies avoids the occurrence of open corners at the turning points, ensuring the consistency and stability of the forging dimensions and the smoothness and defects of the corners. Then, by adjusting the die forging state of the forging die, the bent die forging part is placed in the cavity of the lower die core for secondary die forging to form the balance shaft forging. This forging process has a simple process flow and improves the production efficiency and yield of the balance shaft.

[0094] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the invention.

[0095] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0096] Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The reference to "embodiment" herein means that a specific feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily indicate the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0097] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A forging die for bending and forming a balance shaft, characterized in that, include: A lower mold base, wherein a lower mold core is provided on the top surface of the lower mold base along a first direction, and a lower mold cavity is provided on the surface of the lower mold core opposite to the surface of the lower mold base; A pre-forging lower die is fitted onto the lower die core. The edge of the top surface of the pre-forging lower die is provided with a lower groove extending to the side end face. The lower groove is configured for partial contour forging of the balance shaft. A limiting assembly is rotatably connected to the side end face of the pre-forging lower die near the lower mold groove. The limiting assembly includes a rotating shaft rotatably connected to the pre-forging lower die and at least one roller connected to one end of the rotating shaft and extending to the lower mold groove. The roller is configured for limiting and fixing during the bending forming process of the balance shaft. The adjustment assembly includes a telescopic member disposed on the bottom surface of the lower die base and a sliding frame disposed on the top surface of the lower die base and connected to the output end of the telescopic member; the sliding frame is used to adjust the height position of the pre-forging lower die in the first direction so that the pre-forging lower die can be adapted to the bending forming stage and the die forging and milling stage in the forging process of the balance shaft. The forging assembly includes a support frame mounted on the lower die base, a drive motor mounted on the support frame, a heavy-duty lead screw connected to the drive motor, and a pre-forging upper die mounted on the end of the heavy-duty lead screw away from the drive motor. The surface edge of the pre-forging upper die facing the pre-forging lower die is provided with an upper groove extending to the side end face. The upper groove and the lower groove cooperate to form a cavity for bending the balance shaft. An upper die core is connected inside the pre-forging upper die, and the bottom surface of the upper die core is provided with an upper cavity that cooperates with the lower cavity. The pre-forging lower die bottom surface has a through hole extending to the lower mold groove along the first direction. A slide rod is slidably connected in the through hole. A reset elastic element is coaxially sleeved on the part of the slide rod facing away from the lower mold groove. The sliding frame is provided with a push rod arranged along the second direction. When the sliding frame slides along the second direction, the push rod at least partially abuts against one end of the slide rod, so that the other end of the slide rod extends into the lower mold groove. The first direction is the height direction of the lower mold base, and the second direction is the width direction of the lower mold base.

2. The forging die for bending and forming a balance shaft according to claim 1, characterized in that, The lower pre-forging die and the upper pre-forging die are arranged opposite each other in the first direction. The die surfaces of the lower groove and the upper groove are at least partially constructed as curved surfaces, and the shapes of the two die surfaces are complementary. During the bending forming stage, the lower groove and the upper groove are closed to form the bending cavity of the balance shaft.

3. The forging die for bending and forming a balance shaft according to claim 2, characterized in that, The lower groove has a pressure-resistant area on its side. The limiting assembly also includes a torsion spring sleeved on the rotating shaft and a limiting rod connected to one end of the rotating shaft and forming an angle with the roller. The torsion spring is used to reset the rotating shaft after rotation. The end of the limiting rod away from the rotating shaft extends to the pressure-resistant area to limit the end of the balance shaft. When the upper groove is pressed down toward the lower groove to abut the limiting rod, the limiting rod rotates within the pressure-resistant area.

4. The forging die for bending and forming a balance shaft according to any one of claims 1-3, characterized in that, The lower pre-forging die has a first guide cavity extending through it along the first direction, and the lower die core passes through the first guide cavity and is slidably connected to the lower pre-forging die; the upper pre-forging die has a second guide cavity extending through it along the first direction, and the upper die core passes through the second guide cavity and is selectively slidably connected to the upper pre-forging die.

5. The forging die for bending and forming a balance shaft according to claim 4, characterized in that, The support frame has limiting plates arranged along the first direction on opposite sides of the pre-forging upper die. The pre-forging upper die has a locking block with one end abutting the surface of the limiting plate on both sides near the limiting plate. The upper die core side end has a locking groove that cooperates with the locking block. The limiting plate is configured to change the connection method between the pre-forging upper die and the lower die core through the locking block, so that the pre-forging upper die can adapt to the bending and forming stage and the die forging and milling stage in the forging process of the balance shaft.

6. The forging die for bending and forming a balance shaft according to claim 5, characterized in that, The limiting plate is provided with a bending portion and a first limiting portion and a second limiting portion located at the upper and lower ends of the bending portion. The distance between the two first limiting portions is less than the distance between the two second limiting portions. When the locking block is located at the first limiting portion, one end of the locking block extends into the locking groove to fix the pre-forging upper die and the upper die core. When the locking block is located at the second limiting portion, one end of the locking block is located outside the locking groove to slide the pre-forging upper die and the upper die core.

7. The forging die for bending and forming a balance shaft according to claim 5, characterized in that, The sliding frame includes a frame body and a crossbar disposed at one end of the frame body near the limiting plate. The crossbar is used to adjust the position of the limiting plate in the first direction. The bottom surface of the pre-forging lower die is provided with a pulley group that contacts a portion of the surface of the frame body. The frame body is used to adjust the position of the pre-forging lower die in the first direction.

8. The forging die for bending and forming a balance shaft according to claim 1, characterized in that, The lower die base surface is provided with a plurality of sleeves spaced around the lower die core, and the bottom surface of the pre-forging lower die is provided with a plurality of guide rods extending into the sleeves. The sleeves are used for guiding and limiting the pre-forging lower die when it slides in the first direction.

9. A forging process for bending and forming a balance shaft, characterized in that, The forging process is carried out based on a forging die for bending and forming a balance shaft as described in any one of claims 1-8, and the forging process includes: The raw materials are deburred and pretreated, then heated and then forged into billets using conventional methods to obtain pre-forged parts with rough shapes. The cooled pre-forging part is reheated, and the upper groove of the pre-forging upper die and the lower groove of the pre-forging lower die are preheated. The position of the pre-forging lower die and the limiting plate is adjusted so that the forging die is in the first forging state, which is adapted to the bending forming stage. The heated initial forging is placed in the lower mold groove and fixed by the limiting component. The drive motor is controlled to move the pre-forging upper mold toward the pre-forging lower mold. The pre-forging is bent and then forged using the upper mold groove and the lower mold groove to form a bent forging. The bent forging is removed and the hot material is reheated in the furnace. The upper cavity of the upper die core and the lower cavity of the lower die core are preheated. The position of the pre-forging lower die and the limiting plate is adjusted so that the forging die is in the second forging state. The second forging state is adapted to the forging milling stage. The heated bending forging is placed in the preheated lower cavity, and the drive motor is controlled to move the upper die core toward the lower die core. The bending forging is then subjected to secondary die forging using the upper and lower cavities to form a balance shaft forging.

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