A forked flange forging process

Abstract

The application discloses a fork protruding flange forging process, which comprises the following process steps: forging part design, blanking, heating, upsetting, pre-forging, final forging, edge cutting, quenching and tempering, and shot blasting. The forging process is reasonable in design and easy to operate, the fork protruding flange forging part is reasonable in structure design, the processing allowance of the forging part is moderate, the utilization rate of metal material is 90%, the production of the same weight of conventional forgings is close to that of the test class, the consistency of the forging quality is improved, the waste rate is reduced, and the service life of the die is stable.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of automobile industry, and particularly relates to a forked flange forging process. BACKGROUND

[0002] The forked flange is applied to the drive system of a heavy truck for transmitting power and torque. The existing forked flange usually adopts a casting as a machining blank, which has the advantages of a through hole that can be cast, a small ejection slope, and a small overall machining allowance. However, the casting blank may have defects such as sand holes, air holes, and shrinkage, and the overall waste rate after machining is high. Meanwhile, the mechanical properties of the casting are insufficient, which affects the performance and safety of the forked flange.

[0003] The finished forked flange is shown in FIGS. Figure 1 , Figure 2 and Figure 3 , which includes an upper part, a middle part, and a lower part. The upper part is two symmetrical square protrusions 1, and the upper end surface of the square protrusion 1 has an arc-shaped groove 2 in the middle. The middle part is a large-diameter and small-thickness disc 3, and the disc 3 has a square shallow groove 4 at the center of the upper surface. The lower part is a small-diameter and large-height conical cylindrical structure 5. In addition to the square shallow groove 4 at the center of the disc 3, the inside of the disc 3 and the upper part of the inner hole of the conical cylindrical structure 5 are multiple cylindrical stepped hollow structures 6. The middle and lower parts of the inner hole of the conical cylindrical structure 5 are spline hole structures 7. The forked flange with this structure has the following problems in the forging process:

[0004] 1) The cross-sectional areas of the upper part, the middle part, and the lower part of the finished forked flange are quite different. The cross-sectional area of the disc 3 in the middle part is 5 times that of the square protrusion 1 in the upper part and 7 times that of the conical cylindrical structure 5 in the lower part. This has a great influence on the selection of the raw material specification and the forging process. When the raw material specification is large, it is easy to cause the material utilization rate to decrease and the lower end of the forging to be difficult to fill. When the raw material specification is small, the height-to-diameter ratio of the raw material becomes large, which may cause folding and other problems.

[0005] 2) The shape of the square protrusion 1 is quite different from that of the cylindrical bar, which is difficult to fill during forging. Moreover, the square protrusion 1 has an arc-shaped groove 2 in the middle, which is also prone to folding defects during forging.

[0006] 3) The hollow height of the conical cylindrical structure 5 in the lower part is relatively large compared with the diameter, which is difficult to completely forge the middle hole. Meanwhile, the cylindrical stepped hollow structure 6 is also prone to folding defects during forging. Therefore, factors such as the machining allowance and the forging forming requirement need to be considered to reduce the overall production cost as much as possible.

[0007] 4) The middle and lower part of the fork flange is a rotary body, and the circumferential direction thereof cannot be positioned during the forging process, which does not affect the forming of the rotary part, but the two square protrusions 1 of the upper part will be folded and cannot be filled due to the mispositioning of the finish forging and pre-forging, resulting in the rejection of the forgings. SUMMARY

[0008] The present application provides a fork flange forging process which is reasonable in design, easy to operate, less likely to cause metal material folding, high in forming rate, and low in comprehensive cost.

[0009] To solve the above technical problems, the present application adopts the following technical scheme: a fork flange forging process comprising the following process steps: forging part design, blanking, heating, upsetting, pre-forging, finish forging, edge cutting, quenching and tempering, and shot blasting.

[0010] The forging part design process specifically includes the following contents: the three part structures of the upper part, the middle part and the lower part of the fork flange finished product are quite different, and when designing the forgings, factors such as blank selection, blank pretreatment, pre-forging design and finish forging forming are also considered in addition to meeting the processing requirements of the fork flange finished product parts.

[0011] In order to minimize the machining allowance, the arc-shaped groove in the middle part of the two square protrusions of the upper part of the fork flange needs to be forged; at the same time, since the hollow height of the lower part of the cylindrical structure is twice the diameter, a more complex and higher cost forging process is needed to completely forge a through hole, and considering the cost, an upper reserved groove and a lower reserved groove need to be forged on the upper and lower parts of the fork flange, and a through hole is machined subsequently. In order to meet the above two points, the fork flange selects the vertical forging mode, the parting line is selected at the middle position of the middle disc, the complex coefficient of the fork flange forging part is 0.21, and it belongs to the S3 level which is relatively complex in forming.

[0012] The whole forging process is mainly based on upsetting forming, and the square protruding part is mainly based on reverse extrusion forming; in the upsetting forming process, the height-diameter ratio of the blank has an important influence on the stability of the forming process, and the stable forming height-diameter ratio recommended by the die design manual is generally not more than 2.5, and when it exceeds 3, there is a great possibility of producing folding, underfilling and other forging defects; in this design, in order to reduce the machining amount of the outer side of the lower cylindrical structure, φ75 round bar stock is used as the blank, the height-diameter ratio of the blank is 3.6, and the adverse effects caused by the too large height-diameter ratio need to be reduced through the cooperation between blank pretreatment, pre-forging and final forging; therefore, a conical surface with a diameter of φ76 and a draft angle of 3° is designed on the outer side of the cylindrical structure; in the forming process, the central disc belongs to upsetting forming and is more likely to be filled, and the square protrusion belongs to reverse extrusion forming, and only after the central disc is filled, the blank will flow more to the square protruding part; the area of the square protrusion is quite different from that of the central disc, and only the blank of the disc part connected with the square protrusion can enter the square protrusion cavity of the die, and the rest of the blank is more likely to flow to the parting line, finally forming a flash; the height a of the square protrusion is 2.5 times the width b, in order to reduce the deformation resistance of the blank during the reverse extrusion forming of the square protrusion, and also to avoid too much blank flowing out from the parting line of the disc part due to difficult filling, resulting in reduced material utilization, a larger draft angle needs to be set on the left and right sides of the square protrusion; at the same time, too large draft angle will increase the weight of the forked flange itself, which will adversely affect the use of the forked flange, and also increase the production cost; finally, the slope on both sides is determined to be 7°.

[0013] The specific process of the blanking process is: the forked flange raw material uses φ75mm 40Cr, and the blanking length is 270±0.5mm; P100B high-speed circular saw machine is used to cut the blank, the equipment speed is 100-110r / s, the tooth cutting thickness is 0.065-0.07mm, the blanking length tolerance is ±0.05mm, and the end face horse hoof degree is ≤0.1mm; the high-speed circular saw machine has high blanking speed and high blank precision, which is conducive to the consistency of the forging quality.

[0014] The specific process of the heating process is that a cylindrical blank is heated by using a 1000KW intermediate frequency induction heating furnace, the heating temperature ranges from 1100 to 1200 DEG C, the blank temperature control method is that the heated blank is sorted by using an infrared temperature detector, the sorting is that normal blank (1100-1200 DEG C), low-temperature blank (<1100 DEG C) and high-temperature blank (>1200 DEG C), the sorted blank reaches the designated position through different slides. The low-temperature blank and high-temperature blank slide terminals are provided with low-temperature blank baskets and high-temperature blank baskets, the baskets are provided with feeding ports and are locked to ensure that the blanks are not mixed and the workers cannot take unqualified blanks; the low-temperature blank can be reused once, and the second time of under-temperature is scrapped to avoid multiple heating to cause the forging organization not to meet the requirements; the high-temperature blank is scrapped, and the quality personnel clean the high-temperature blank regularly and mark and isolate it.

[0015] The upsetting process is that the heated cylindrical blank is placed into the upsetting blank mold, the upsetting blank mold includes an upsetting upper mold and an upsetting lower mold located directly below the upsetting upper mold, the lower surface of the upsetting upper mold is provided with a positioning shallow circular groove, the inside of the upsetting lower mold is provided with a cylindrical blind hole with an open top, the upsetting lower mold is provided with a protrusion at the bottom of the cylindrical blind hole, the protrusion is a circular truncated cone with a small top and a large bottom, the center lines of the cylindrical blind hole, the protrusion and the positioning shallow circular groove coincide, and the protrusion outer circle and the lower part of the cylindrical blind hole inner circle form an upsetting annular groove; the cylindrical blind hole is a circular cone with a large bottom and a small top, the draft angle of the cylindrical blind hole is 3 DEG; the diameter of the lower end of the cylindrical blind hole and the diameter of the positioning shallow circular groove are both 78mm; the depth of the positioning shallow circular groove is 3mm, the height of the protrusion is 4mm, and the maximum diameter of the protrusion is 40mm; a guide hole is provided in the inside of the upsetting lower mold along the center line of the cylindrical blind hole, the upper end of the guide hole is located at the center of the upper end surface of the protrusion, a upsetting ejector rod is arranged in the guide hole, and the lower end of the upsetting ejector rod is connected with an upsetting demolding air cylinder for driving the upsetting ejector rod to move up and down.

[0016] The specific process of the upsetting process is that the cylindrical blank is placed into the cylindrical blind hole, the lower end of the cylindrical blank is in contact with the upper surface of the protrusion, the upsetting upper mold is lowered to make the upper end of the cylindrical blank extend into the inside of the positioning shallow circular groove, the groove bottom of the positioning shallow circular groove is in contact with the upper end surface of the cylindrical blank, so that the vertical state of the cylindrical blank can be determined, the blank can be vertically aligned when upsetting, then the positioning upper mold is raised and vertically downward to upset the blank, so that the deformation of the blank is more uniform, the lower reserved groove is formed by the protrusion, the lower part of the blank fills the cylindrical blind hole, and the diameter of the upper part of the blank above the cylindrical blind hole is increased, and the upsetting blank is ejected by controlling the upsetting ejector rod to move upward by the upsetting demolding air cylinder when demolding.

[0017] The pre-forging process is performed by placing the upset blank into the pre-forging die. The pre-forging die includes a pre-forging upper die and a pre-forging lower die. The bottom of the pre-forging upper die and the top of the pre-forging lower die enclose a pre-forging cavity. The lower surface of the pre-forging upper die and the upper surface of the pre-forging lower die form a horizontal pre-forging parting surface around the pre-forging cavity. The pre-forging cavity includes a pre-forging left prong cavity, a pre-forging right prong cavity, a pre-forging disc cavity, and a pre-forging cylindrical cavity. The center lines of the pre-forging disc cavity and the pre-forging cylindrical cavity coincide and are arranged in a vertical direction. The upper half of the pre-forging disc cavity is located in the pre-forging upper die, and the lower half of the pre-forging disc cavity is located in the pre-forging lower die. The pre-forging left prong cavity and the pre-forging right prong cavity are symmetric about the center line of the pre-forging disc cavity. The lower end of the pre-forging left prong cavity is in communication with the left side of the top of the pre-forging disc cavity, and the lower end of the pre-forging right prong cavity is in communication with the right side of the top of the pre-forging disc cavity. The upper end of the pre-forging cylindrical cavity is in communication with the bottom of the pre-forging disc cavity. The pre-forging lower die has a pre-forging boss with a circular truncated cone shape inside the bottom of the pre-forging cylindrical cavity. The pre-forging boss coincides with the center line of the pre-forging cylindrical cavity. The outer circle of the pre-forging boss and the inner wall of the lower end of the pre-forging cylindrical cavity form a pre-forging annular groove. The inner circle of the pre-forging cylindrical cavity has a draft angle of 5-10°. A pre-forging vertical hole is formed in the pre-forging lower die along the center line of the pre-forging cylindrical cavity. The upper end of the pre-forging vertical hole is located at the center of the upper end surface of the pre-forging boss. A pre-forging ejector pin is arranged in the pre-forging vertical hole. The lower end of the pre-forging ejector pin is connected to a pre-forging cylinder for driving the pre-forging ejector pin to move up and down. Two pre-forging positioning grooves are formed in the upper surface of the pre-forging lower die. The two pre-forging positioning grooves are symmetrically arranged about the center line of the pre-forging disc cavity. The two pre-forging positioning grooves are in communication with the outer circle of the pre-forging disc cavity.

[0018] The specific process of the pre-forging process is as follows. First, the upset blank is placed into the pre-forging cylindrical cavity of the pre-forging lower die. The pre-forging boss is inserted into the lower reserved groove at the lower end of the blank to keep the blank centered. Then, the pre-forging upper die moves downward to forge the blank. The lower part of the blank fills the pre-forging cylindrical cavity. The middle part of the blank expands outward to fill the pre-forging disc cavity. The lower reserved groove is further deepened. The upper part of the blank finally fills the pre-forging left prong cavity and the pre-forging right prong cavity. In the pre-forging process, the metal material overflows on the pre-forging parting surface around the outer periphery of the pre-forging disc cavity to form a flash. At the same time, the metal material enters the two pre-forging positioning grooves to form final forging positioning blocks. The final forging positioning blocks position the pre-forging piece placed in the final forging die cavity during final forging. After the pre-forging operation is completed, the pre-forging upper die moves upward. The pre-forging cylinder drives the pre-forging ejector pin to move upward to eject the pre-forging piece, thereby completing the pre-forging piece demolding.

[0019] The final forging process is performed by placing the pre-forging piece into the final forging die. The final forging die includes a final forging upper die and a final forging lower die. The bottom of the final forging upper die and the top of the final forging lower die enclose a final forging cavity. The lower surface of the final forging upper die and the upper surface of the final forging lower die form a horizontal final forging parting surface around the final forging cavity. The final forging cavity includes a final forging left fork cavity, a final forging right fork cavity, a final forging disc cavity, and a final forging cylindrical cavity. The center lines of the final forging disc cavity and the final forging cylindrical cavity coincide and are arranged in a vertical direction. The upper half of the final forging disc cavity is located in the final forging upper die, and the lower half of the final forging disc cavity is located in the final forging lower die. The final forging left fork cavity and the final forging right fork cavity are symmetric about the center line of the final forging disc cavity. The lower end of the final forging left fork cavity is in communication with the left side of the top of the final forging disc cavity, and the lower end of the final forging right fork cavity is in communication with the right side of the top of the final forging disc cavity. The upper end of the final forging cylindrical cavity is in communication with the bottom of the final forging disc cavity. Arc-shaped protrusions are arranged in the middle of the upper end surfaces of the final forging left fork cavity and the final forging right fork cavity. The lower surface of the final forging upper die is integrally provided with a pressing block that extends into the upper part of the final forging cylindrical cavity. The final forging lower die is provided with a final forging boss in the bottom of the final forging cylindrical cavity. The final forging boss is in the form of a circular truncated cone with a thin upper part and a thick lower part. The center line of the final forging boss coincides with the center line of the final forging cylindrical cavity, and the outer circle of the final forging boss forms a final forging annular groove with the inner wall of the lower end of the final forging cylindrical cavity. The inner circle of the final forging cylindrical cavity has a draft angle of 5-10°. A final forging vertical hole is arranged in the final forging lower die along the center line of the final forging cylindrical cavity. The upper end of the final forging vertical hole is located in the center of the upper end surface of the final forging boss. A final forging ejector pin is arranged in the final forging vertical hole. The lower end of the final forging ejector pin is connected to a final forging cylinder for driving the final forging ejector pin to move up and down. Two final positioning grooves are arranged on the upper surface of the final forging lower die. The horizontal cross section of the final positioning groove is rectangular. The length direction of the final positioning groove is consistent with the radial direction of the final forging disc cavity. The width of the vertical cross section of the final positioning groove gradually decreases from top to bottom. The two final positioning grooves are symmetrically arranged about the center line of the final forging disc cavity. The two final positioning grooves are in communication with the outer circle of the final forging disc cavity. A flash bin in the form of a circular ring is arranged between the lower surface of the final forging upper die and the upper surface of the final forging lower die. The center line of the flash bin coincides with the center line of the final forging disc cavity. The inner diameter of the flash bin is greater than the maximum diameter of the final forging disc cavity.

[0020] The specific process of the final forging process is as follows: first, the pre-forging piece is placed into the final forging cylindrical cavity of the final forging lower die, the final forging boss is inserted into the lower reserved groove at the lower end of the pre-forging piece, and the two final forging positioning blocks are respectively placed into the two final forging positioning grooves, so that the two square protrusions on the upper part of the pre-forging piece are respectively one-to-one corresponding to the final forging left fork cavity and the final forging right fork cavity in the final forging upper die in an up-down manner; then the final forging upper die moves downward to forge the pre-forging piece, the lower part of the pre-forging piece fills the final forging cylindrical cavity, the middle part of the pre-forging piece expands outward to fill the final forging disc cavity, the lower reserved groove is further deepened, the two arc protrusions forge the top of the two square protrusions on the top of the pre-forging piece to form arc grooves, the pressing block forges the center of the disc part to form the upper reserved groove and the square shallow groove, and the excess metal material is collected into the flash pocket from the parting surface; after the final forging operation is completed, the final forging upper die moves upward, the final forging cylinder drives the final forging ejector rod to move upward to eject the final forging piece, and the final forging piece is demolded.

[0021] The trimming process is performed by placing the final forging piece into the trimming die. The trimming die includes a trimming upper die and a trimming lower die located below the trimming upper die. The trimming lower die is provided with a blanking hole in the center. The trimming upper die is provided with an open-bottom containing groove in the inside. The center line of the containing groove and the center line of the blanking hole are both vertical and coincident. The trimming upper die is provided with an upper threaded hole at the top center for connecting with the upper die frame of the press. The trimming lower die is provided with lower threaded holes at the four corners for connecting with the lower die frame of the press. The trimming upper die is integrally provided with a positioning square protrusion around the upper end of the upper threaded hole on the upper surface. The blanking hole is conical with a small upper end and a large lower end. The trimming upper die has a cylindrical structure with a diameter equal to the diameter of the upper end of the blanking hole. The diameter of the disc part of the fork flange final forging piece is slightly smaller than the diameter of the upper end of the blanking hole.

[0022] The specific process of the trimming process is as follows: the final forging piece is inverted, i.e., the two square protrusions are downward, the two fork ears (square protrusions) of the final forging piece are placed downward into the blanking hole, and the disc part of the final forging piece remains horizontal with the lower half of the disc part located in the upper end of the blanking hole. The flash lower surface is supported on the upper surface of the trimming lower die. When the trimming upper die moves downward to press the upper surface of the disc part, the cylindrical structure of the final forging piece is inserted into the containing groove. Only the disc part is in contact with the lower end of the trimming upper die during the trimming process. The flash is blocked by the trimming lower die and is separated from the disc part. The trimmed forging piece falls through the blanking hole.

[0023] The specific process of the tempering process is as follows: the tempering treatment is carried out by using a net belt type fuel gas heating continuous furnace, the furnace loading mode is that a gear reducer is used to overturn the frame containing the parts to make the workpieces fall into a vibrating feeder, the vibrating feeder uniformly lays the workpieces on the net belt through vibration, the loading amount of the furnace is about 1000 Kg per hour, the heating and heat preservation treatment is carried out at 830-850 DEG C for 94 minutes, then the workpieces are quenched in a cooling pool for 100 S after being discharged from the furnace, the cooling medium concentration is 4-6% PAG, the medium temperature is 55-60 DEG C, then the heat preservation treatment is carried out in the furnace at 620-680 DEG C for 100 minutes; the surface hardness of the product after the quenching and tempering heat treatment is between 229-269 HBW.

[0024] The specific process of the shot blasting process is as follows: the shot blasting is carried out by using a 1200 Kg crawler type shot blasting machine, special cast steel shots are used in the shot blasting machine, and double-layer dust removal cloth bags are used; the cast steel shots are not easy to be pulverized and will not increase dust, and the double-layer cloth bag dust removal is carried out; the oxide skin dropped on the surface of the product is fully filtered and will not be scattered into the air; the product surface is free of defects such as cracks, oxide skin and collision marks; the loading amount of the 1200 Kg crawler type shot blasting machine is not more than 240 pieces, the shot blasting current is 20-25 A, the shot blasting time is 25-30 minutes, and the cast steel shot specification is ¢0.8-1 mm.

[0025] By using the technical scheme, the main processes of the application are upsetting, pre-forging, final forging and trimming, and the four processes have the following beneficial effects:

[0026] 1、The preform blank is formed by upsetting, the upsetting lower die is designed as a cylindrical blind hole with a diameter of φ78mm and an inclination of 3°, the cylindrical blank can be directly placed into the cylindrical blind hole. When the upsetting lower die is processed, a fillet with a radius of R5mm is processed around the bottom of the cylindrical blind hole (between the outer ring of the bottom of the annular groove and the inner circle of the cylindrical blind hole), which prevents the cylindrical blank from folding due to sharp corners on the bottom circumference, and also prevents stress concentration in the upsetting lower die from causing cracks, thereby improving the service life of the die. A protrusion with a diameter of φ40mm and a height of 4mm is designed in the middle of the bottom of the cylindrical blind hole, the lower end surface of the blank is in contact with the upper surface of the φ40mm protrusion when the blank is placed, the circumferential direction of the blank is in contact with the inner wall of the lower end of the cylindrical blind hole, which can be placed conveniently and stably, and is beneficial to improve the stability of the upsetting process. The protrusion makes the lower end of the blank have a pit after upsetting, which corresponds to the pit on the lower end surface of the preform, and can reduce the wear of the preform die at this position. A positioning shallow circular groove with a diameter of φ78mm and a depth of 3mm is designed on the lower surface of the upsetting upper die, which can move downward during upsetting, so that the upper end of the cylindrical blank extends into the positioning shallow circular groove, the groove bottom of the positioning shallow circular groove is in contact with the upper end surface of the cylindrical blank, which can determine that the cylindrical blank remains vertical, ensures that the blank is aligned vertically during upsetting, and then the positioning upper die is moved upward and then vertically downward to upset the blank, which can make the deformation of the blank more uniform. In addition, the lower end of the blank almost immediately contacts the inner wall of the cylindrical blind hole of the upsetting lower die after the upsetting starts, reaches a stable state, and the blank continues to deform by upsetting above the upsetting lower die, thereby reducing the height-diameter ratio of the deformed part of the blank, meeting the height-diameter ratio requirement of stable deformation, finally completing the forming upsetting, and obtaining a suitable blank. Since the 3° draft angle is small, it is not conducive to ejection, therefore a guide hole is designed inside the upsetting lower die, the extension and retraction of the ejector rod is controlled by the air cylinder, the blank is ejected after the upsetting is completed, which can reduce the difficulty of operation of workers and improve production efficiency.

[0027] 2. The two square protrusions of the fork-shaped flange are the most difficult parts to form in the forging. During pre-forging, the focus is on allocating blank material to these square protrusions. Since the upper surfaces of the pre-forged left and right fork cavities are flat, the cross-sections of these cavities are gradually increased from top to bottom. This makes it easier for the material to fill the fork cavities and facilitates demolding. The draft angle of the pre-forged cylindrical cavity is 5-10°, preferably 8°. The draft angle at the lower end of the pre-forged cylindrical cavity can be increased to 10°, saving material and facilitating demolding. The pre-forging boss can be matched with the blank after the upsetting process and the final forging die cavity, allowing for convenient and quick centering and positioning of the blank and the pre-forged part in the final forging die, improving worker efficiency. The pre-forging boss can also pre-form a groove in the lower part of the final forging, reducing the wear rate of the final forging die and extending its service life. The lower parts of the blank, pre-forging, and final forging are all conical rotating bodies, facilitating easy centering. Both the pre-forging and final forging have square protrusions on their upper parts. After the pre-forging is placed in the final forging die, these square protrusions must correspond to the cavity of the die to ensure proper forming and prevent defects such as folding or incomplete filling. The pre-forging boss is a rotating body, which prevents accurate and rapid positioning of the square protrusions after the pre-forging is placed in the cavity of the final forging die. Therefore, corresponding positioning grooves are provided on the lower die surfaces of both the pre-forging and final forging dies. This allows the protrusions on the flash of the pre-forging to fit into the final forging positioning grooves on the surface of the final forging die, ensuring accurate alignment of the square protrusions with the cavity. This design reduces operator skill requirements, improves production efficiency, and increases the yield of finished forgings. A pre-forging ejector rod is installed inside the pre-forging lower die. When the forging is demolded, the pre-forging cylinder is activated to drive the pre-forging ejector rod to move upward. The pre-forging ejector rod lifts the pre-forging part upward, and the operator uses clamps to hold the plate to demold the pre-forging part.

[0028] 3、The two square protrusions of the finished product of the forked flange are the most difficult parts to form in the forging, and the blank distribution is focused on the square protrusions during pre-forging, the upper end faces of the final-forging left fork cavity and the final-forging right fork cavity are flat structures; the top surfaces of the final-forging left fork cavity and the final-forging right fork cavity are provided with arc protrusions, so that the arc-shaped grooves in the middle of the upper end faces of the two square protrusions of the finished product of the forked flange are directly forged (extruded) out after final forging. The draft angle of the final-forging cylindrical cavity is 5-10°, preferably 8°, and the draft angle of the lower end of the final-forging cylindrical cavity can be increased to 10°, which saves material and facilitates demolding. The setting of the final-forging boss can cooperate with the lower reserved groove at the lower end of the pre-forging piece after the pre-forging process, so that the pre-forging piece can be conveniently and quickly centered and positioned when placed in the final-forging die, improving the production efficiency of workers. The setting of the boss can form the bottom blind hole of the final-forging piece, reducing the machining amount for subsequent machining into a spline hole. The upper part of the pre-forging piece and the upper part of the final-forging piece both have square protrusions, and after the pre-forging piece is placed in the final-forging die, its square protrusions must correspond to the final-forging left fork cavity and the final-forging right fork cavity to ensure the forming of the final-forging piece without defects such as folding and underfilling. The final-forging boss is a rotary body, which causes the square protrusions of the pre-forging piece to be unable to be accurately and quickly positioned after being placed in the final-forging cavity, so corresponding final-forging positioning grooves are arranged on the lower die surface of the pre-forging die and the final-forging die. In this way, the burrs of the pre-forging piece after pre-forging have final-forging positioning blocks, and the two final-forging positioning blocks can be clamped in the positioning grooves on the lower die surface of the final-forging die, so that the two square protrusions of the pre-forging piece correspond to the final-forging left fork cavity and the final-forging right fork cavity accurately. Thus, the operation requirements for workers are low, which is conducive to improving production efficiency and increasing the yield of forged products. A final-forging ejector pin is arranged inside the final-forging lower die, and when the final-forging piece is demolded, the final-forging cylinder is started to drive the final-forging ejector pin to move upward, and the final-forging ejector pin moves the final-forging piece upward, and the worker uses a clamp to hold the disc part to demold the final-forging piece. The lower surface of the final-forging upper die is integrally provided with a pressing block extending into the upper part of the final-forging cylindrical cavity, so that the upper reserved groove in the center of the top of the disc part of the final-forging piece is forged out, corresponding to the lower reserved groove, for subsequent machining into a spline hole to reduce the machining amount. During the final-forging process, the metal material extruded out of the final-forging cavity is stored in the flash warehouse through the final-forging parting surface, so that the thickness of the flash generated by the gap of the final-forging parting surface is reduced, and only thin flash needs to be cut during edge cutting, thereby reducing the edge cutting workload.

[0029] 4、The upper die and the lower die are respectively installed below the upper die holder and above the lower die holder of the 400-ton closed single-point press, the guide rail gap of the 400-ton closed single-point press is less than or equal to 0.3 mm, the consistency of the circumferential burr of the forged piece after trimming is ensured; a conveying belt is additionally installed beside the press, the forked flange final forging piece after forging is placed on the conveying belt to cool down, and the bumping damage caused by the accumulation of the forged pieces can be effectively avoided; in order to facilitate the operation of workers, the two forked ears (square protrusions of the finished product) of the forked flange final forging piece are placed downward into the blanking hole during trimming, the disc part of the forked flange final forging piece is kept horizontal, the lower half of the disc part is located in the upper port of the blanking hole, and the lower surface of the flash is supported on the upper surface of the trimming lower die; since the disc part is a rotary body, the position of the final forging piece with flash does not need to be specially adjusted when being placed into the trimming lower die. A bottom-open containing groove is arranged in the trimming upper die, when the trimming upper die moves downward to press the upper surface of the disc part, the columnar structure (the conical cylindrical structure of the finished product) of the forked flange final forging piece is inserted into the containing groove, only the disc part is in contact with the lower end annular surface of the trimming upper die during trimming, the flash is blocked by the trimming lower die and separated from the disc part, and the forged piece after trimming falls through the blanking hole. The trimming die structure of the present application is simple, easy to manufacture, avoids the deformation of the forged piece caused by trimming, and affects the product quality of the forged piece. In order to ensure the consistency of the trimming quality of the final forging piece and reduce the trimming deformation, an infrared temperature measuring instrument is installed on the trimming press to measure the temperature of the final forging piece (adjust and fix the probe of the infrared temperature measuring instrument to ensure the consistency of the measuring position), and the trimming temperature of the forged piece is specified as 750-850 DEG C. When the temperature of the forged piece is within the temperature range, the worker performs trimming operation, and the forged piece after trimming is placed on the conveying belt to cool down and flow to the next process. When the temperature of the forged piece exceeds the temperature range, the infrared temperature measuring instrument alarms, the worker places the forged piece into a to-be-treated product basket, and the basket is transferred, isolated or scrapped after being inspected by a quality inspector.

[0030] In summary, the forging process of the present application is reasonable in design and easy to operate, the forked flange forging piece is reasonable in structure design, the processing allowance of the forged piece is moderate, the utilization rate of metal material is 90%, the production of the tested shift is close to that of the conventional forged piece with the same weight, the quality consistency of the forged piece is improved, the scrap rate is reduced, and the service life of the die is stable. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a structure schematic view of the forked flange finished product;

[0032] Figure 2 is a left view of Figure 1 ;

[0033] Figure 3 is a top view of Figure 1 ;

[0034] Figure 4 is a structure schematic view of the upsetting die;

[0035] Figure 5 is a structural schematic view of a pre-forging die;

[0036] Figure 6 is a top view of a pre-forging lower die;

[0037] Figure 7 is Figure 6 a D-D sectional view thereof;

[0038] Figure 8 is a structural schematic view of a final-forging die;

[0039] Figure 9 is a top view of a final-forging lower die;

[0040] Figure 10 is Figure 9 a E-E sectional view thereof;

[0041] Figure 11 is a structural schematic view of a trimming die

[0042] Figure 12 is a structural schematic view of a forked flange forging piece forged by the forging process of the present application

[0043] Figure 13 is Figure 12 a left view thereof;

[0044] Figure 14 is Figure 12 a top view thereof. DETAILED DESCRIPTION

[0045] As shown in Figures 4-14 , a forked flange forging process of the present application comprises the following process steps: forging piece design → blanking → heating → upsetting → pre-forging → final forging → trimming → quenching and tempering → shot blasting.

[0046] The forging piece design process specifically comprises the following contents: the upper, middle and lower three part structures of the forked flange finished product are quite different, when the forging piece is designed, in addition to meeting the machining requirements of the forked flange finished product parts, factors such as blank selection, blank pretreatment, pre-forging design and final-forging forming also need to be considered;

[0047] In order to minimize the machining allowance, the arc-shaped groove in the middle part of the two square protrusions on the fork flange upper part needs to be forged; at the same time, due to the hollow height of the lower cylindrical structure being twice the diameter, a more complex and higher cost forging process is needed to completely forge a through hole, considering the cost, a upper and lower reserved groove needs to be forged on the fork flange, and a through hole is machined subsequently. In order to meet the above two points, the fork flange chooses vertical forging, and the parting line is selected at the middle position of the middle disc. The complex coefficient of the fork flange forging is 0.21, which belongs to the S3 level of forming;

[0048] The whole forging process is mainly based on upsetting forming, and the square protrusion part is mainly based on reverse extrusion forming; during the upsetting forming process, the height-diameter ratio of the blank has an important influence on the stability of the forming process. The stable forming height-diameter ratio recommended by the die design manual is generally not more than 2.5, and when it exceeds 3, there is a high possibility of folding, underfilling and other forging defects; in this design, in order to reduce the machining amount of the outside of the lower cylindrical structure, a φ75 round bar is used as the blank, and the height-diameter ratio of the blank is 3.6, which needs to be reduced through the cooperation between blank pretreatment, pre-forging and finish forging to reduce the adverse effects of the too large height-diameter ratio; therefore, a taper surface with a diameter of φ76 and a draft angle of 3° is designed on the outside of the cylindrical structure; during the forming process, the middle disc belongs to upsetting forming and is more likely to be filled, and the square protrusion belongs to reverse extrusion forming, and only after the middle disc is filled, the blank will flow more to the square protrusion part; the area of the square protrusion and the middle disc is quite different, only the disc part at the joint of the square protrusion can enter the square protrusion cavity of the die, and the rest of the blank is more likely to flow to the parting line, finally forming a flash; the height a of the square protrusion is 2.5 times the width b, in order to reduce the deformation resistance of the blank during the reverse extrusion forming of the square protrusion, and also to avoid too much blank being discharged from the parting line of the disc part due to filling difficulty, resulting in a decrease in material utilization, a larger draft angle needs to be set on the left and right sides of the square protrusion; at the same time, too large draft angle will increase the weight of the fork flange itself, which is not conducive to the use of the fork flange, and also increases the production cost; finally, the slope of the two sides is determined to be 7°.

[0049] The specific process of the blanking process is: the fork flange raw material uses φ75mm 40Cr, and the blanking length is 270±0.5mm; P100B high-speed circular saw machine is used to cut the blank, the equipment speed is 100-110r / s, the tooth cutting thickness is 0.065-0.07mm, the blanking length tolerance is ±0.05mm, and the end face horse hoof degree is ≤0.1mm; the high-speed circular saw machine has fast blanking speed and high blank precision, which is conducive to the consistency of the forging quality.

[0050] The specific process of the heating process is that a cylindrical blank is heated by using a 1000KW intermediate frequency induction heating furnace, the heating temperature ranges from 1100 to 1200 DEG C, the blank temperature control method is that the heated blank is sorted by using an infrared temperature detector, the sorting is that normal blank (1100-1200 DEG C), low-temperature blank (<1100 DEG C) and high-temperature blank (>1200 DEG C), the sorted blank reaches the designated position through different slides. The low-temperature blank and high-temperature blank slide terminals are provided with low-temperature blank baskets and high-temperature blank baskets, the baskets are provided with feeding ports and are locked to ensure that the blanks are not mixed and the workers cannot take the unqualified blanks; the low-temperature blank can be reused once, the second time of under-temperature heating is scrapped to avoid that the forging organization does not meet the requirements due to multiple heating; the high-temperature blank is scrapped, the quality personnel clean the high-temperature blank regularly and mark and isolate the high-temperature blank.

[0051] The upsetting process is that the heated cylindrical blank is placed into the upsetting blank mold, the upsetting blank mold includes an upsetting upper mold 33 and an upsetting lower mold 34 located directly below the upsetting upper mold 33, the lower surface of the upsetting upper mold 33 is provided with a positioning shallow circular groove 35, the inside of the upsetting lower mold 34 is provided with a cylindrical blind hole 36 with an open top, the upsetting lower mold 34 is provided with a protrusion 37 at the bottom of the cylindrical blind hole 36, the protrusion 37 is a circular truncated cone with a small top and a large bottom, the center lines of the cylindrical blind hole 36, the protrusion 37 and the positioning shallow circular groove 35 coincide, the protrusion 37 outer circle and the lower part of the cylindrical blind hole 36 inner circle form an upsetting annular groove 38; the cylindrical blind hole 36 is a circular cone with a large bottom and a small top, the draft angle of the cylindrical blind hole 36 is 3 DEG; the diameter of the lower end of the cylindrical blind hole 36 and the diameter of the positioning shallow circular groove 35 are both 78mm; the depth of the positioning shallow circular groove 35 is 3mm, the height of the protrusion 37 is 4mm, and the maximum diameter of the protrusion 37 is 40mm; the inside of the upsetting lower mold 34 is provided with a guide hole 39 along the center line of the cylindrical blind hole 36, the upper end of the guide hole 39 is located at the center of the upper end surface of the protrusion 37, and the guide hole 39 is provided with an upsetting ejector rod (not shown in the figure), and the lower end of the upsetting ejector rod is connected with an upsetting demolding air cylinder (not shown in the figure) for driving the upsetting ejector rod to move up and down.

[0052] The specific process of the upsetting process is that the cylindrical blank is placed into the cylindrical blind hole 36, the lower end of the cylindrical blank is in contact with the upper surface of the protrusion 37, the upsetting upper mold 33 moves downward, the upper end of the cylindrical blank extends into the inside of the positioning shallow circular groove 35, the groove bottom of the positioning shallow circular groove 35 is in contact with the upper end surface of the cylindrical blank, so that the vertical state of the cylindrical blank can be determined, the blank can be vertically aligned when upsetting, then the positioning upper mold moves upward and vertically downward to upset the blank, so that the deformation of the blank is more uniform, the lower reserved groove 53 is formed by the protrusion 37, the lower part of the blank fills the cylindrical blind hole 36, and the diameter of the upper part of the blank above the cylindrical blind hole 36 increases, and the upsetting blank is pushed out by the upsetting ejector rod moving upward under the control of the upsetting demolding air cylinder when demolding.

[0053] The pre-forging process is to place the upset blank into the pre-forging die, the pre-forging die includes a pre-forging upper die 8 and a pre-forging lower die 9, the bottom of the pre-forging upper die 8 and the top of the pre-forging lower die 9 enclose a pre-forging cavity, the lower surface of the pre-forging upper die 8 and the upper surface of the pre-forging lower die 9 form a horizontal pre-forging parting surface 10 around the pre-forging cavity, the pre-forging cavity includes a pre-forging left fork cavity 11, a pre-forging right fork cavity 12, a pre-forging disc cavity 13 and a pre-forging cylindrical cavity 14, the center lines of the pre-forging disc cavity 13 and the pre-forging cylindrical cavity 14 coincide and are arranged in the vertical direction, the upper half of the pre-forging disc cavity 13 is in the pre-forging upper die 8, the lower half of the pre-forging disc cavity 13 is in the pre-forging lower die 9, the pre-forging left fork cavity 11 and the pre-forging right fork cavity 12 are symmetrical about the center line of the pre-forging disc cavity 13, the lower end of the pre-forging left fork cavity 11 is communicated with the left side of the top of the pre-forging disc cavity 13, the lower end of the pre-forging right fork cavity 12 is communicated with the right side of the top of the pre-forging disc cavity 13, the upper end of the pre-forging cylindrical cavity 14 is communicated with the bottom of the pre-forging disc cavity 13; the pre-forging lower die 9 is provided with a pre-forging boss 15 with a circular truncated cone shape with a thin upper part and a thick lower part at the bottom of the pre-forging cylindrical cavity 14, the pre-forging boss 15 coincides with the center line of the pre-forging cylindrical cavity 14, a pre-forging annular groove 16 is formed between the outer circle of the pre-forging boss 15 and the inner wall of the lower end of the pre-forging cylindrical cavity 14; the inner circle of the pre-forging cylindrical cavity 14 has a 5-10° draft angle; the pre-forging lower die 9 is provided with a pre-forging vertical hole 17 along the center line of the pre-forging cylindrical cavity 14, the upper end of the pre-forging vertical hole 17 is located at the center of the upper end surface of the pre-forging boss 15, the pre-forging vertical hole 17 is provided with a pre-forging ejector rod (not shown in the figure), the lower end of the pre-forging ejector rod is connected with a pre-forging cylinder (not shown in the figure) for driving the pre-forging ejector rod to move up and down; the upper surface of the pre-forging lower die 9 is provided with two pre-forging positioning grooves 18, the two pre-forging positioning grooves 18 are symmetrically arranged about the center line of the pre-forging disc cavity 13, and the two pre-forging positioning grooves 18 are communicated with the outer circle of the pre-forging disc cavity 13;

[0054] The specific process of the pre-forging process is as follows: first, place the upset blank into the pre-forging cylindrical cavity 14 of the pre-forging lower die 9, the pre-forging boss 15 extends into the lower reserved groove 53 at the lower end of the blank to keep the center of the blank, then the pre-forging upper die 8 moves downward to forge the blank, the lower part of the blank fills the pre-forging cylindrical cavity 14, the middle part of the blank expands outward to fill the pre-forging disc cavity 13, the lower reserved groove 53 is further deepened, and the upper part of the blank finally fills the pre-forging left fork cavity 11 and the pre-forging right fork cavity 12, in the pre-forging process, the metal material overflows on the pre-forging parting surface 10 around the outer periphery of the pre-forging disc cavity 13 to form a flash, and enters the two pre-forging positioning grooves 18 to form a finish-forging positioning block, the finish-forging positioning block positions the pre-forging piece placed in the finish-forging die cavity during finish-forging, after the pre-forging operation is completed, the pre-forging upper die 8 moves upward, the pre-forging cylinder drives the pre-forging ejector rod to move upward to eject the pre-forging piece, and the pre-forging piece is demolded.

[0055] The final forging process is carried out by placing the pre-forging piece into the final forging die. The final forging die includes a final forging upper die 19 and a final forging lower die 20. The bottom of the final forging upper die 19 and the top of the final forging lower die 20 enclose a final forging cavity. The lower surface of the final forging upper die 19 and the upper surface of the final forging lower die 20 form a horizontal final forging parting surface 21 around the final forging cavity. The final forging cavity includes a final forging left fork cavity 22, a final forging right fork cavity 23, a final forging disc cavity 24, and a final forging cylindrical cavity 25. The center line of the final forging disc cavity 24 and the final forging cylindrical cavity 25 coincide and is arranged in the vertical direction. The upper half of the final forging disc cavity 24 is located in the final forging upper die 19, and the lower half of the final forging disc cavity 24 is located in the final forging lower die 20. The final forging left fork cavity 22 and the final forging right fork cavity 23 are symmetric about the center line of the final forging disc cavity 24. The lower port of the final forging left fork cavity 22 communicates with the left side of the top of the final forging disc cavity 24, and the lower port of the final forging right fork cavity 23 communicates with the right side of the top of the final forging disc cavity 24. The upper port of the final forging cylindrical cavity 25 communicates with the bottom of the final forging disc cavity 24. Arc-shaped protrusions 26 are provided in the middle of the upper end surfaces of the final forging left fork cavity 22 and the final forging right fork cavity 23. The lower surface of the final forging upper die 19 is integrally provided with a press block 27 that extends into the upper part of the final forging cylindrical cavity 25. A final forging boss 28 in the shape of a circular truncated cone is provided in the final forging lower die 20 at the bottom of the final forging cylindrical cavity 25. The final forging boss 28 coincides with the center line of the final forging cylindrical cavity 25, and the outer circle of the final forging boss 28 forms a final forging annular groove 29 with the inner wall of the lower end of the final forging cylindrical cavity 25. The inner circle of the final forging cylindrical cavity 25 has a draft angle of 5-10°. A final forging vertical hole 30 is provided in the final forging lower die 20 along the center line of the final forging cylindrical cavity 25. The upper port of the final forging vertical hole 30 is located in the center of the upper end surface of the final forging boss 28. A final forging ejector pin (not shown) is provided in the final forging vertical hole 30. The lower end of the final forging ejector pin is connected to a final forging cylinder (not shown) for driving the final forging ejector pin to move up and down. Two final positioning grooves 31 are provided on the upper surface of the final forging lower die 20. The horizontal cross-section of the final positioning groove 31 is rectangular. The length direction of the final positioning groove 31 is consistent with the radial direction of the final forging disc cavity 24. The vertical cross-section of the final positioning groove 31 gradually decreases from top to bottom. The two final positioning grooves 31 are symmetrically arranged about the center line of the final forging disc cavity 24, and communicate with the outer circle of the final forging disc cavity 24. A flash bin 32 in the shape of a circular ring is provided between the lower surface of the final forging upper die 19 and the upper surface of the final forging lower die 20. The center line of the flash bin 32 coincides with the center line of the final forging disc cavity 24, and the inner diameter of the flash bin 32 is greater than the maximum diameter of the final forging disc cavity 24.

[0056] The specific process of the final forging step is as follows: first, the pre-forging piece is placed into the final-forging cylindrical cavity 25 of the final-forging lower die 20, the final-forging boss 28 is inserted into the lower reserved groove 53 at the lower end of the pre-forging piece, and the two final-forging positioning blocks are placed into the two final-forging positioning grooves 31, so that the two square protrusions on the upper part of the pre-forging piece are one-to-one corresponding to the final-forging left prong cavity 22 and the final-forging right prong cavity 23 of the final-forging upper die 19 in an up-down manner; then the final-forging upper die 19 is moved downward to forge the pre-forging piece, the lower part of the pre-forging piece fills the final-forging cylindrical cavity 25, the middle part of the pre-forging piece expands outward to fill the final-forging disc cavity 24, the lower reserved groove 53 is further deepened, the two arc protrusions 26 forge the two square protrusions on the top of the pre-forging piece into arc grooves, the pressing block 27 forges the center of the disc part into the upper reserved groove 51 and the square shallow groove 52, and the excess metal material is collected into the flash pocket 32 by the parting surface; after the final-forging operation is completed, the final-forging upper die 19 is moved upward, the final-forging cylinder drives the final-forging ejector rod to move upward to eject the final-forging piece, and the final-forging piece is demolded.

[0057] The trimming step is performed by placing the final-forging piece into the trimming die. The trimming die includes a trimming upper die 41 and a trimming lower die 42 located below the trimming upper die 41. The trimming lower die 42 is provided with a blanking hole 43 in the center. The trimming upper die 41 is provided with an open-bottom containing groove 44 inside. The center line of the containing groove 44 and the center line of the blanking hole 43 are perpendicular and coincide. The trimming upper die 41 is provided with an upper threaded hole 45 at the top center for connecting with the upper die holder of the press. The trimming lower die 42 is provided with lower threaded holes (not shown in the figure) at the four corners for connecting with the lower die holder of the press. The trimming upper die 41 is integrally provided with a positioning square protrusion 46 on the upper surface around the upper end of the upper threaded hole 45. The blanking hole 43 is conical with a small upper end and a large lower end. The trimming upper die 41 is a cylindrical structure with a diameter equal to the diameter of the upper end of the blanking hole 43. The disc part of the prong flange final-forging piece is slightly smaller in diameter than the diameter of the upper end of the blanking hole 43.

[0058] The specific process of the trimming step is as follows: the final-forging piece is inverted, i.e., the two square protrusions are downward, the two prong ears 48 (square protrusions) of the final-forging piece are placed into the blanking hole 43, and the disc part of the final-forging piece remains horizontal with the lower half of the disc part 47 located in the upper end of the blanking hole 43 and the lower surface of the flash 49 supported on the upper surface of the trimming lower die 42. When the trimming upper die 41 moves downward to press the upper surface of the disc part 47, the cylindrical structure 50 of the final-forging piece is inserted into the containing groove 44. During the trimming process, only the disc part 47 is in contact with the lower end of the trimming upper die 41, and the flash 49 is blocked by the trimming lower die 42 and separated from the disc part. The trimmed forging piece falls through the blanking hole 43.

[0059] The specific process of the tempering process is as follows: the tempering treatment is performed by using a net belt type fuel gas heating continuous furnace, the furnace loading mode is that a gear reducer is used to overturn the frame containing the parts to make the workpieces fall into a vibrating feeder, the vibrating feeder uniformly lays the workpieces on the net belt through vibration, the loading amount of the furnace is about 1000 Kg per hour, the heating and holding treatment is performed at 830-850 DEG C for 94 minutes, then the workpieces are quenched in a cooling pool for 100 S after being discharged from the furnace, the cooling medium concentration is 4-6% PAG, the medium temperature is 55-60 DEG C, then the workpieces are held in the furnace for 100 minutes at 620-680 DEG C; the surface hardness of the product after the tempering heat treatment is between 229-269 HBW.

[0060] The specific process of the shot blasting process is as follows: the shot blasting is performed by using a 1200 Kg crawler type shot blasting machine, special cast steel shots are used in the shot blasting machine, and double-layer dust removal cloth bags are used. The cast steel shots are not easy to be pulverized and do not increase dust, and the double-layer cloth bag dust removal is performed; the oxide skin dropped from the product surface is fully filtered and does not scatter into the air. The product surface is free of defects such as cracks, oxide skin and collision marks; the loading amount of the 1200 Kg crawler type shot blasting machine is not more than 240 pieces, the shot blasting current is 20-25 A, the shot blasting time is 25-30 minutes, and the cast steel shot specification is ¢0.8-1 mm.

[0061] The embodiment is not limited in shape, material, structure and the like in any form, and any simple modification, equivalent change and modification made according to the technical essence of the embodiment are within the protection scope of the technical scheme.

Claims

1. A forging process for a fork-shaped flange, characterized in that: The process includes the following steps: forging design → blanking → heating → upsetting → pre-forging → final forging → trimming → tempering → shot blasting; The forging design process specifically includes the following: The upper, middle and lower parts of the finished fork flange have significant structural differences. When designing the forging, in addition to meeting the processing requirements of the finished fork flange parts, factors such as billet selection, billet pretreatment, pre-forging design and final forging should also be taken into account. To minimize machining allowance, the arc-shaped groove between the two square protrusions on the upper part of the fork flange needs to be forged. At the same time, since the hollow height of the lower cylindrical structure is twice the diameter, a more complex and costly forging process needs to be designed to completely forge a through hole. Considering the overall cost, an upper reserved groove and a lower reserved groove need to be forged on the upper and lower parts of the fork flange, and the through hole will be machined later. To meet the above two requirements, the fork flange is forged vertically, and the parting line is located in the middle of the central disk. The complexity coefficient of the fork flange forging is 0.21, which belongs to the relatively complex S3 level. The entire forging process is mainly upsetting, while the square protrusion is mainly formed by reverse extrusion. During upsetting, the aspect ratio of the billet significantly affects the stability of the forming process. The die design manual recommends a stable aspect ratio of no more than 2.5; exceeding 3 greatly increases the likelihood of folding and incomplete forging defects. In this design, to reduce the machining amount on the outer side of the lower cylindrical structure, a φ75 round bar is used as the billet, with an aspect ratio of 3.

6. The adverse effects of an excessively large aspect ratio need to be mitigated through the coordination of billet pretreatment, pre-forging, and final forging. Therefore, a conical surface with a φ76 diameter and a 3° draft angle is designed on the outer side of the cylindrical structure. During the forming process, the central disc is upsetting, making it easier to fill the gap, while the square protrusion is formed by reverse extrusion. Only in the central disc... After the central disc is filled, the blank will flow more towards the square protrusion. The area difference between the square protrusion and the central disc is significant; only the blank at the part of the disc that connects to the square protrusion can enter the square protrusion cavity of the mold. The remaining blank flows more easily towards the parting line, ultimately forming flash. The height 'a' of the square protrusion is 2.5 times its width 'b'. To reduce the deformation resistance of the blank during the reverse extrusion forming process of the square protrusion, and to prevent excessive blank from being discharged from the parting line of the disc due to filling difficulties, thus reducing material utilization, a large draft angle needs to be set on both sides of the square protrusion. However, an excessively large draft angle will increase the weight of the fork flange itself, negatively impacting its use and increasing production costs. Finally, the draft angle on both sides was determined to be 7°.

2. The forging process for a fork-shaped flange according to claim 1, characterized in that: The specific process of blanking is as follows: φ75mm 40Cr raw material is used for the fork flange, and the blanking length is 270±0.5mm; the blank is sawed using a P100B high-speed circular saw with a rotation speed of 100-110r / s, a tooth thickness of 0.065-0.07mm, a blanking length tolerance of ±0.05mm, and an end face horseshoe degree ≤0.1mm; the high-speed circular saw has a fast blanking speed and high blanking accuracy, which is a favorable condition for improving the consistency of forging quality.

3. The forging process for a fork-shaped flange according to claim 1, characterized in that: The specific process of the heating process is as follows: a 1000KW medium-frequency induction heating furnace is used to heat the cylindrical billet, with a heating temperature range of 1100-1200℃. The billet temperature is controlled by using an infrared thermometer to sort the heated billet into three categories: normal billet (1100-1200℃), low-temperature billet (<1100℃), and high-temperature billet (>1200℃). The sorted billets are then transported to designated positions via different slides. Low-temperature and high-temperature material chute terminals are equipped with low-temperature material baskets and high-temperature material baskets, with inlets on the baskets and locks to ensure that materials do not mix and prevent workers from taking unqualified billets; low-temperature material can be reused once, and scrapped if it is underheated again to avoid the forging structure not meeting requirements due to repeated heating; high-temperature material is scrapped, and quality personnel regularly clean the high-temperature material and mark and isolate it.

4. The forging process for a fork-shaped flange according to claim 1, characterized in that: The upsetting process involves placing a heated cylindrical billet into an upsetting mold. The upsetting mold includes an upper upsetting mold and a lower upsetting mold located directly below it. The lower surface of the upper upsetting mold has a shallow positioning groove, and the interior of the lower upsetting mold has a cylindrical blind hole with an open top. A protrusion, shaped like a frustum of a cone (thinner at the top and thicker at the bottom), is located at the bottom of the cylindrical blind hole on the lower upsetting mold. The centerlines of the cylindrical blind hole, the protrusion, and the shallow positioning groove coincide, forming an upsetting annular groove between the outer circle of the protrusion and the lower part of the inner circle of the cylindrical blind hole. The cylindrical blind hole is conical, thicker at the top and thinner at the bottom, with a draft angle of 3°. The diameter of the lower end of the cylindrical blind hole and the diameter of the shallow positioning groove are both 78 mm; the depth of the shallow positioning groove is 3 mm. The height of the protrusion is 4mm, and the maximum diameter of the protrusion is 40mm. A guide hole is provided inside the lower upsetting die along the center line of the cylindrical blind hole. The upper end of the guide hole is located at the center of the upper end face of the protrusion. An upsetting ejector rod is provided in the guide hole. The lower end of the upsetting ejector rod is connected to an upsetting demolding cylinder for driving the upsetting ejector rod to move up and down. The specific process of upsetting is as follows: The cylindrical blank is placed into the cylindrical blind hole, with the lower end of the cylindrical blank in contact with the upper surface of the protrusion. The upsetting upper die moves down, so that the upper end of the cylindrical blank extends into the positioning shallow circular groove. The bottom of the positioning shallow circular groove is in contact with the upper end surface of the cylindrical blank. This ensures that the cylindrical blank remains vertical and that the blank is aligned vertically during upsetting. Then, the positioning upper die moves up and then vertically downwards to upset the blank. This makes the blank deformation more uniform. The lower reserved groove is formed by the protrusion. The lower part of the blank fills the cylindrical blind hole, and the diameter of the upper part of the blank above the cylindrical blind hole increases. During demolding, the upsetting ejector rod is moved upward by the upsetting cylinder to eject the upset blank.

5. The forging process for a fork-shaped flange according to claim 4, characterized in that: The pre-forging process involves placing the upset billet into a pre-forging die. The pre-forging die includes an upper pre-forging die and a lower pre-forging die. The bottom of the upper pre-forging die and the top of the lower pre-forging die together form a pre-forging cavity. A horizontal pre-forging parting surface is formed around the pre-forging cavity between the lower surface of the upper pre-forging die and the upper surface of the lower pre-forging die. The pre-forging cavity includes a left fork cavity, a right fork cavity, a disc cavity, and a cylindrical cavity. The centerlines of the disc cavity and the cylindrical cavity coincide and are vertically aligned. The upper half of the disc cavity is located in the upper pre-forging die, and the lower half is located in the lower pre-forging die. The left and right fork cavities are symmetrical about the centerline of the disc cavity. The lower port of the left fork cavity connects to the top left side of the disc cavity, and the lower port of the right fork cavity connects to the top left side of the disc cavity. The top right side of the disc cavity is connected, and the upper port of the pre-forged cylindrical cavity is connected to the bottom of the pre-forged disc cavity. The lower pre-forging die has a frustum-shaped pre-forging boss at the bottom of the pre-forged cylindrical cavity, which is thinner at the top and thicker at the bottom. The pre-forging boss coincides with the center line of the pre-forged cylindrical cavity, and a pre-forging annular groove is formed between the outer circle of the pre-forging boss and the inner wall of the lower end of the pre-forged cylindrical cavity. The inner circle of the pre-forged cylindrical cavity has a draft angle of 5-10°. A pre-forging vertical hole is opened inside the lower pre-forging die along the center line of the pre-forged cylindrical cavity. The upper port of the pre-forging vertical hole is located at the center of the upper surface of the pre-forging boss. A pre-forging ejector rod is provided in the pre-forging vertical hole, and the lower end of the pre-forging ejector rod is connected to a pre-forging cylinder for driving the pre-forging ejector rod to move up and down. Two pre-forging positioning grooves are opened on the upper surface of the lower pre-forging die. The two pre-forging positioning grooves are symmetrically arranged about the center line of the pre-forged disc cavity, and the two pre-forging positioning grooves are connected to the outer circle of the pre-forged disc cavity. The specific process of pre-forging is as follows: First, the upset billet is placed into the pre-forging cylindrical cavity of the pre-forging lower die. The pre-forging boss extends into the lower reserved groove at the bottom of the billet to keep the billet centered. Then, the pre-forging upper die moves downward to forge the billet. The lower part of the billet fills the pre-forging cylindrical cavity, and the middle part of the billet expands outward to fill the pre-forging disc cavity. The lower reserved groove is further deepened. Finally, the upper part of the billet fills the pre-forging left fork cavity and the pre-forging right fork cavity. During the pre-forging process, the metal material overflows onto the pre-forging parting surface on the outer periphery of the pre-forging disc cavity to form flash. At the same time, it enters the two pre-forging positioning grooves to form the final forging positioning block. The final forging positioning block positions the pre-forged part placed in the final forging die cavity during the final forging. After the pre-forging operation is completed, the pre-forging upper die moves upward, and the pre-forging cylinder drives the pre-forging ejector rod to move upward to eject the pre-forged part, completing the demolding of the pre-forged part.

6. A forging process for a fork-shaped flange according to claim 5, characterized in that: The final forging process involves placing the pre-forged part into the final forging die. The final forging die includes an upper final forging die and a lower final forging die. The bottom of the upper final forging die and the top of the lower final forging die together form a final forging cavity. A horizontal final forging parting surface is formed around the final forging cavity between the lower surface of the upper final forging die and the upper surface of the lower final forging die. The final forging cavity includes a left fork cavity, a right fork cavity, a disc cavity, and a cylindrical cavity. The centerlines of the disc cavity and the cylindrical cavity coincide and are arranged vertically. The upper half of the disc cavity is located in the upper final forging die, and the lower half is located in the lower final forging die. The left and right fork cavities are positioned about the center of the disc cavity. The design is symmetrical. The lower port of the left fork cavity of the final forging is connected to the top left side of the cavity of the final forging disc, and the lower port of the right fork cavity of the final forging is connected to the top right side of the cavity of the final forging disc. The upper port of the cylindrical cavity of the final forging is connected to the bottom of the cavity of the final forging disc. Both the upper end face of the left and right fork cavities of the final forging are provided with an arc-shaped protrusion. The lower surface of the upper die of the final forging is integrally provided with a pressure block whose lower end extends into the upper part of the cylindrical cavity of the final forging. The lower die of the final forging is provided with a frustum-shaped final forging boss at the bottom of the cylindrical cavity of the final forging, which is thinner at the top and thicker at the bottom. The center line of the final forging boss coincides with the center line of the cylindrical cavity of the final forging. The outer circle of the final forging boss and the inner wall of the lower end of the cylindrical cavity of the final forging form a final forging annular groove. The inner circle of the cylindrical cavity of the final forging has a draft angle of 5-10°. A final forging vertical hole is formed inside the lower final forging die along the center line of the final forging cylindrical cavity. The upper end of the final forging vertical hole is located at the center of the upper surface of the final forging boss. A final forging ejector rod is provided inside the final forging vertical hole, and the lower end of the final forging ejector rod is connected to a final forging cylinder for driving the final forging ejector rod to move up and down. Two final forging positioning grooves are formed on the upper surface of the lower final forging die. The horizontal cross-section of the final forging positioning groove is rectangular. The length direction of the final forging positioning groove is consistent with the radial direction of the final forging disc cavity. The width of the vertical cross-section of the final forging positioning groove gradually decreases from top to bottom. The two final forging positioning grooves are symmetrically arranged about the center line of the final forging disc cavity and are connected to the outer circle of the final forging disc cavity. A circular flash compartment is provided between the lower surface of the upper final forging die and the upper surface of the lower final forging die. The center line of the flash compartment coincides with the center line of the final forging disc cavity, and the inner diameter of the flash compartment is larger than the maximum diameter of the final forging disc cavity. The specific process of the final forging is as follows: First, the pre-forged part is placed into the final forging cylindrical cavity of the lower forging die. The final forging boss extends into the lower reserved groove at the bottom of the pre-forged part. At the same time, two final forging positioning blocks are placed into the two final forging positioning grooves respectively. This makes the two square protrusions on the upper part of the pre-forged part correspond one-to-one with the upper and lower parts of the left and right forging cavities of the final forging die in the upper forging die. Then, the upper forging die moves downward to forge the pre-forged part. The lower part of the pre-forged part fills the final forging cylindrical cavity, and the middle part of the pre-forged part expands outward to fill the final forging disc cavity. The lower reserved groove is further deepened. The two arc protrusions forge arc grooves on the top of the two square protrusions on the top of the pre-forged part. The pressure block forges the upper reserved groove and square shallow groove in the center of the disc. Excess metal material flows into the flash bin from the parting surface. After the final forging operation is completed, the upper forging die moves upward, and the final forging cylinder drives the final forging ejector rod to move upward to eject the final forging part, completing the demolding of the final forging part.

7. The forging process for a fork-shaped flange according to claim 6, characterized in that: The trimming process involves placing the final forging into a trimming die. The trimming die includes an upper trimming die and a lower trimming die located below it. The lower trimming die has a blanking hole at its center, and the upper trimming die has an open-bottomed receiving groove inside. The center line of the receiving groove and the center line of the blanking hole are perpendicular and coincident. The upper trimming die has an upper threaded hole at its top center for connection with the upper die frame of the press, and the lower trimming die has lower threaded holes at its four corners for connection with the lower die frame of the press. The upper surface of the upper trimming die has an integrally formed locating square protrusion around the upper port of the upper threaded hole. The blanking hole is conical with a tapered shape at the top and a thicker shape at the bottom. The upper trimming die has a cylindrical structure with a diameter equal to the diameter of the upper port of the blanking hole. The diameter of the disc portion of the fork-flange final forging is slightly smaller than the diameter of the upper port of the blanking hole. The specific process of the trimming process is as follows: the final forging is inverted, that is, the two square protrusions face down, and the two forked ears of the final forging are placed downward into the blanking hole. The disc part of the final forging is kept horizontal, and the lower half of the disc part is located in the upper port of the blanking hole. The lower surface of the flash is supported on the upper surface of the trimming die. When the trimming die moves downward and presses against the upper surface of the disc part, the cylindrical structure of the final forging extends into the receiving groove. During the trimming process, only the disc part is pressed against the lower end ring surface of the trimming die. The flash is blocked by the trimming die and detaches from the disc part. The trimmed forging falls through the blanking hole.

8. The forging process for a fork-shaped flange according to claim 7, characterized in that: The specific process of the quenching and tempering process is as follows: a mesh belt gas-heated continuous furnace is used for quenching and tempering. The furnace loading method is to use a reducer to flip the material frame containing the parts so that the workpieces are poured into the vibrating feeder. The vibrating feeder spreads the workpieces evenly on the mesh belt through vibration. The loading amount is 1000Kg per hour. The workpieces are heated and held at 830-850℃ for 94 minutes. After being taken out of the furnace, they are quenched in a cooling pool for 100 seconds. The cooling medium concentration is 4-6% PAG and the medium temperature is 55-60℃. Then, they are held at 620-680℃ in the furnace for 100 minutes. After quenching and tempering heat treatment, the surface hardness of the product is between 229-269HBW.

9. The forging process for a fork-shaped flange according to claim 8, characterized in that: The specific process of shot blasting is as follows: a 1200Kg crawler shot blasting machine is used for shot blasting, and special cast steel shot and double-layer dust collection bags are used in the shot blasting machine. Cast steel shot is not easily pulverized and will not increase dust. It is filtered by double-layer bag dust collection. The oxide scale removed by shot blasting on the product surface is fully filtered and will not be dispersed into the air. The product surface is free of defects such as cracks, oxide scale, and dents; 1200Kg crawler shot blasting machine load: no more than 240 pieces, shot blasting current: 20-25A, shot blasting time: 25-30 minutes, cast steel shot specification: ¢0.8-1mm.

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