Hub extrusion forming method based on streamline regulation and control

Abstract

The invention discloses a hub extrusion forming method based on streamline regulation and control, which comprises the following steps: firstly, designing a blank with a reasonable height-diameter ratio, and then placing the prefabricated blank in a finish forging die for forging and pressing to form a final hub forging and pressing piece; and finally, the prefabricated blank is placed in a finish forging die to be forged and pressed, and a final hub forged and pressed part is formed. A streamline regulation and control method is introduced on the basis of a hub forging and pressing process, namely, a prefabricated blank design is additionally arranged, and fillet parameters and taper parameters of various structures in an upsetting die and a finish forging die are controlled, so that folding generated in the forging and pressing process is further prevented, shape-following reasonable distribution of metal streamlines of a hub forging and pressing piece is achieved, and the yield of the hub forging and pressing piece is improved. And the performance and the service life of the hub are greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of wheel hub casting technology, and in particular relates to a wheel hub extrusion forming method based on streamline control. Background Art

[0002] Domestic research on wheels mainly focuses on isothermal forging of aluminum alloy wheels. After isothermal forging, the forging structure is significantly finer than that of ordinary forging, and the mechanical properties are significantly improved. The use of isothermal forging blanks can also strengthen the final forging streamline of the forging. With the development of precision forging technology, a large number of high-quality, efficient, energy-saving and labor-saving precision forging technologies have emerged one after another, and the use of precision forging to manufacture wheels has gradually become a mainstream trend.

[0003] In precision forging, the metal streamlines (fibers) of the forging are reasonably distributed along the contour of the part, which can improve the load-bearing capacity of the part, thereby improving the performance and service life of the wheel hub. However, the concept of streamline control has not been proposed for the manufacturing of automobile wheels. Summary of the invention

[0004] The purpose of the present invention is to provide a wheel hub extrusion forming method based on streamline control, which introduces a streamline control method on the basis of the wheel hub forging process to greatly improve the performance and service life of the wheel hub.

[0005] To achieve the above object, the solution of the present invention is: a wheel hub extrusion forming method based on streamline control, comprising the following steps: S1. Design a billet with a reasonable height-to-diameter ratio: Prepare a cylindrical blank, the height of the blank is h, the diameter is d, wherein 0.9 <h / d<1.6; S2. Preform design: Placing the blank in an upsetting die for pre-upsetting to form a pre-formed blank; The upsetting die comprises an upsetting punch and an upsetting die, an upsetting cavity is formed between the upsetting punch and the upsetting die, the upper portion of the upsetting cavity is a cylindrical cavity, the diameter of the cylindrical cavity is D1, the lower portion of the upsetting cavity is an inverted truncated cone-shaped conical cavity, the taper of the conical cavity is θ1, and an upwardly convex arc-shaped protrusion is provided in the middle of the bottom surface of the conical cavity, and the fillet radius of the arc-shaped protrusion is R1; S3, Final Forging: The preformed blank is placed in the final forging die for forging to form the final wheel hub forging part; The finish forging die includes a forging punch and a forging die cavity. In the middle of the bottom surface of the forging punch, a reverse conical upper ejector block protrudes downward. The taper of the upper ejector block is θ2, and the bottom end of the upper ejector block is an arc end with a fillet radius of R2. A forging cavity is formed between the forging punch and the forging die cavity. In the middle of the bottom surface of the forging cavity, a lower ejector block protrudes upward. The top end of the lower ejector block is an arc end with a fillet radius of R3, where R2 < R1 < R3. The upper ejector block and the lower ejector block cooperate up and down to make the cross-section of the hub forging be in the shape of H. A spoke cavity is formed between the upper ejector block and the lower ejector block. The upper outer periphery of the upper ejector block forms a rim cavity. The upper part of the rim cavity is cylindrical with a diameter of D2, where d < D1 < D2. The lower part of the rim cavity is an inverted truncated cone shape with a taper of θ3, where θ3 < θ1 < θ2. The lower outer periphery of the upper ejector block and the outer periphery of the lower ejector block form a rim cavity, and the diameter of the rim cavity is smaller than the diameter of the rim cavity.

[0006] Further, in step S1, 1.1 < h / d < 1.3.

[0007] Further, in step S1, h / d = 1.3.

[0008] Further, in step S2, the height of the cylindrical cavity is H1, and the height of the conical cavity is H2, where H2 < H1.

[0009] Further, in step S3, the upper height of the rim cavity is H3, and the sum of the lower height of the rim cavity and the height of the rim cavity is H4, where H3 < H4.

[0010] Further, in step S2, a convex module protrudes downward in the middle of the bottom surface of the upsetting punch. The diameter of the convex module is D1. The convex module extends into the upsetting die cavity to upset the blank. The bottom surface of the upsetting punch distributed on the outer periphery of the convex module is an abutting plane. When the upsetting punch is pressed downward so that the abutting plane abuts against the top surface of the upsetting die cavity, an upsetting cavity is formed between the upsetting punch and the upsetting die cavity. The upsetting is completed to obtain a preform.

[0011] Further, in step S3, the diameter of the forging punch is D2. The forging punch extends entirely into the forging die cavity to forge the preform. When the forging punch is pressed downward so that the top surface of the forging punch is flush with the top surface of the forging die cavity, a forging cavity is formed between the forging punch and the forging die cavity. The forging is completed to obtain a hub forging.

[0012] Further, in step S1, the blank is 7A04 aluminum alloy.

[0013] After adopting the above scheme, the beneficial effects of the present invention are as follows: In the present invention, a columnar blank with a suitable height-diameter ratio is first selected for pre-forging upsetting to obtain a preform, and then the preform is forged to obtain the final forged hub. The specific effects are as follows: 1. Through experiments, when the height-diameter ratio of the blank is greater than or equal to 1.6, folding will occur at the contact position between the forging punch and the blank during the forging process; when the height-diameter ratio is less than or equal to 0.9, it will cause the metal flow line to deviate from the outer contour of the forged hub in the radial distribution, both of which will affect the bearing capacity of the hub. Therefore, in the present invention, a blank with a height-diameter ratio between 0.9 and 1.6 is selected for preparation to prevent folding of the forged hub and to make the metal flow line distribute along the outer contour of the forged hub in the radial direction, improving the metal flow line state of the forged hub.

[0014] 2. The shape and size and structure of the blank have a great influence on the distribution of the final forming flow line of the hub. A reasonable preform can prevent the phenomena of flow line folding, eddy current and through flow during the forging process. The specific situation is as follows: An arc-shaped protrusion is provided on the bottom surface of the conical cavity, and it is controlled that R2 < R1 < R3. During upsetting, the blank can be distributed on both sides of the arc-shaped protrusion. Then, during the final forging process, the amount of metal flowing downward of the preform decreases. At the position where the upper punch contacts the preform, that is, the position of the formed spoke, folding can be eliminated, making the formed spoke part have greater strength, not easily damaged, and not easily cracked, etc.

[0015] The present invention also controls the taper θ1 of the conical cavity to be greater than the taper θ3 of the outer periphery of the lower part of the rim cavity, so that during upsetting, the metal flow line of the blank has better fluidity in the vertical direction. Thus, during final forging, the metal flow line is more inclined to distribute along the outer contour of the forged hub in the vertical direction, realizing the reasonable conforming distribution of the metal flow line of the forged hub, improving the bearing capacity of the forged hub and extending the fatigue life. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic structural view of the blank of Embodiment 1 of the present invention; Figure 2 is a schematic structural view of the upsetting die of Embodiment 1 of the present invention; Figure 3 is a schematic structural view of the preform of Embodiment 1 of the present invention; Figure 4 is a schematic structural view of the final forging die of Embodiment 1 of the present invention; Figure 5 is a schematic structural view of the forged hub of Embodiment 1 of the present invention; Figure 6 is a schematic structural view of the forged hub of Comparative Example 1; Figure 7 is a folding schematic view of the forged hub of Embodiment 1 of the present invention; Figure 8 Schematic diagram of the folding of the wheel hub forging of comparative example 2 Fig. 9 It is a schematic diagram of the folding of the wheel hub forging of comparative example 3; Fig.10 It is a schematic diagram of the folding of the wheel hub forging of Comparative Example 4; Fig.11 This is the metal streamline distribution diagram of the wheel hub forging of Comparative Example 5; Fig.12 The metal streamline distribution of the hub forging of Example 1 of the present invention Figure 1 ; Fig.13 This is the metal streamline distribution diagram of the wheel hub forging of Comparative Example 6; Fig.14 The metal streamline distribution of the hub forging of Example 1 of the present invention Figure 2 .

[0017] Description of labels: 1. Blank; 2. Upsetting die; 21. Upsetting punch; 211. Male module; 212. Abutment plane; 22. Upsetting die; 221. Arc-shaped protrusion; 222. Ejector rod; 23. Upsetting cavity; 231. Cylindrical cavity; 232. Conical cavity; 3. Preformed blank; 4. Final forging die; 41. Forging punch; 411. Upper ejector block; 42. Forging die; 421. Lower ejector block; 43. Forging cavity; 431. Spoke cavity; 432. Rim cavity; 433. Flange cavity; 5. Hub forging; 51. Spoke; 52. Rim; 53. Flange. DETAILED DESCRIPTION

[0018] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] Stress analysis of wheel hub: The hub bolt holes are located near the wheel core and where they fit with the spokes, i.e. the spoke 51 of the present invention, and have large tensile stress, are very prone to damage, and are prone to defects such as cracks. In addition, during final forging, the transition portion between the spokes and the rim is prone to folding.

[0020] In addition, the fatigue life of wheel hub forgings is closely related to the direction of metal streamlines. Experiments have shown that in extruded billets, the fatigue life in the tensile direction parallel to the metal streamlines is the highest, followed by the fatigue life in the 45° direction, and the lowest is the fatigue life perpendicular to the metal streamlines. The relationship between fatigue life and tensile direction is shown in the following table:

[0021] Therefore, at the position where the hub bears shear force, the streamline here should be perpendicular to the direction of the shear force; at the position where the hub bears tensile stress, the streamline here should be parallel to the direction of the tensile stress. Thus, the direction of the metal streamline needs to be controlled to be substantially conforming to the shape, and the specific distribution shape can be referred to Figure 5 .

[0022] Example 1: As Figure 1-5 shown, to prevent folding of the hub forging and improve the metal streamline state of the hub forging, this embodiment provides a hub extrusion forming method based on streamline control, including the following steps S1. Design a blank with a reasonable height-diameter ratio: Prepare a cylindrical blank 1, the height of the blank 1 is h, and the diameter is d, where 0.9 < h / d < 1.6. And the material of the blank 1 can be 7A04 aluminum alloy. 7A04 aluminum alloy has high strength, corrosion resistance, and good plasticity and toughness, which is suitable for processing hubs.

[0023] During the upsetting process of the blank 1 with a relatively large height-diameter ratio, due to the large deformation, the bending of the metal streamline in the radial direction is more obvious. The metal streamline will be further bent during the subsequent final forging process. Therefore, if the height-diameter ratio of the blank 1 is too large, folding will occur at the contact position between the forging punch 41 and the blank 1 during the forging process. If the height-diameter ratio of the blank 1 is too small, it will cause the metal streamline to deviate from the outer contour of the hub forging 5 in the radial direction (perpendicular to the vertical direction) during the final forging process. Both will affect the bearing capacity of the hub.

[0024] Therefore, designing a reasonable height-diameter ratio of the blank 1 is the prerequisite for controlling the metal streamline. Through experiments, when the height-diameter ratio of the blank 1 is greater than or equal to 1.6, folding will occur at the contact position between the forging punch 41 and the blank 1 during the forging process; when the height-diameter ratio is less than or equal to 0.9, it will cause the metal streamline to deviate from the outer contour of the hub forging 5 in the radial distribution. Thus, in this embodiment, the blank 1 with a height-diameter ratio between 0.9 and 1.6 is designed, which can prevent folding of the hub forging 5 and enable the metal streamline to be distributed along the outer contour of the hub forging 5 in the radial direction, improving the metal streamline state of the hub forging 5. The range of the height-diameter ratio is preferably between 1.1 and 1.3, and the effect of preventing folding and improving the metal flow state is better. Through experiments, the height-diameter ratio of 1.3 is selected in this embodiment, and the effect is the best.

[0025] S2. Preform design: Place the blank 1 in the upsetting die 2 for pre-upsetting, that is, place the blank 1 in the upsetting female die 22, and press down the upsetting male die 21 to the positioning point to form a preform blank 1.

[0026] As Figure 2As shown, the upsetting die 2 includes an upsetting punch 21 and an upsetting die 22, an upsetting cavity 23 is formed between the upsetting punch 21 and the upsetting die 22, the upper portion of the upsetting cavity 23 is a cylindrical cylindrical cavity 231, the diameter of the cylindrical cavity 231 is D1, the height is H1, and the lower portion of the upsetting cavity 23 is an inverted truncated cone-shaped conical cavity 232, the taper of the conical cavity 232 is θ1, and the height is H2, so that the preform 1 after upsetting is as shown in FIG. Figure 3 As shown, the upper part of the preform 1 is cylindrical, and the lower part is an inverted truncated cone with a taper, and the control H2

[0027] Further, the middle part of the bottom surface of the upsetting punch 21 is convex downward to form a convex module 211, the diameter of the convex module 211 is D1, the convex module 211 extends into the inside of the upsetting die 22 to upset the blank 1, and the bottom surface of the upsetting punch 21 distributed on the periphery of the convex module 211 is abutment plane 212, when the upsetting punch 21 is pressed down to make the abutment plane 212 abut against the top surface of the upsetting die 22, the upsetting punch 21 is pressed down to the positioning point, and an upsetting cavity 23 is formed between the upsetting punch 21 and the upsetting die 22, and the upsetting is completed to obtain the preform 1, and the preform 1 is taken out from the upsetting die 2. A push rod 222 is provided at the bottom of the upsetting die 22 to facilitate the removal of the preform 1.

[0028] In addition, in the upsetting die 2, the transition positions between the cylindrical cavity 231 and the conical cavity 232, and between the arc-shaped protrusion 221 and the side wall of the conical cavity 232 are all concave arc-shaped transition surfaces, which facilitate the metal flow of the blank 1 and make the metal flow of the blank 1 smoother.

[0029] S3, Final Forging: The preformed blank 1 is placed inside the final forging die 4 for forging, that is, the preformed blank 1 is placed in the forging die 42, and the forging punch 41 is pressed down to the positioning point to form the final wheel hub forging part 5.

[0030] like Figure 4 ​As shown in the figure, the final forging die 4 includes a forging punch 41 and a forging die 42. In the middle of the bottom surface of the forging punch 41, a downwardly protruding inverted conical upper ejector block 411 is provided. The taper of the upper ejector block 411 is θ2, and the bottom end of the upper ejector block 411 is an arc end with a fillet radius of R2. A forging cavity 43 is formed between the forging punch 41 and the forging die 42. In the middle of the bottom surface of the forging cavity 43, an upwardly protruding lower ejector block 421 is provided. The lower ejector block 421 is located inside the forging die 42, and the top end of the lower ejector block 421 is also an arc end with a fillet radius of R3. It is controlled that R2 < R1 < R3; The upper ejector block 411 and the lower ejector block 421 cooperate up and down to make the cross-section of the hub forging 5 in an H shape. Specifically, a spoke cavity 431 is formed between the upper ejector block 411 and the lower ejector block 421. The preform 1 forms the spoke 51 in the spoke cavity 431. An outer peripheral portion of the upper part of the upper ejector block 411 forms a rim cavity 433. The preform 1 forms the rim 53 in the rim cavity 433. Moreover, the upper part of the rim cavity 433 is cylindrical with a diameter of D2. It is controlled that d < D1 < D2, so that the preform 1 can easily enter the forging die 42. The lower part of the rim cavity 433 is an inverted frustum of a cone with a taper of θ3, where θ3 < θ1 < θ2. An outer peripheral portion of the lower part of the upper ejector block 411 and the outer periphery of the lower ejector block 421 form a rim cavity 432. The diameter of the rim cavity 432 is smaller than the diameter of the rim cavity 433. Moreover, the upper height of the rim cavity 433 is H3, and the sum of the lower height of the rim cavity 433 and the height of the rim cavity 432 is H4. H3 < H4, so that the size of the manufactured hub forging 5 is reasonable.

[0031] The external dimensions and structures of the blank 1 have a great influence on the distribution of the final forming streamline of the hub. A reasonable preform 1 can prevent the phenomena of streamline folding, eddy current and through-flow during the forging process. Therefore, in the present invention, the blank 1 is first placed into the upsetting die 2 for pre-upsetting to obtain the preform 1, and then the preform 1 is placed into the final forging die 4 for final forging to form the hub forging 5. The fillet parameters and taper parameters of various structures in the upsetting die 2 and the final forging die 4 are also controlled to further prevent the folding generated during the forging process and to realize the reasonable conforming distribution of the metal streamline of the hub forging 5. The specific situation is as follows: In the finish forging die 4, the fillet radius at the bottom end of the upper ejector block 411 is R2, and the fillet radius at the top end of the lower ejector block 421 is R3; R2 and R3 are set according to the specific shape of the wheel hub, and R2 < R3. In the upsetting die 2, the fillet radius R1 of the arc-shaped protrusion 221 at the bottom of the upsetting cavity 23 is controlled such that R2 < R1 < R3. This enables the blank 1 to be distributed on both sides of the arc-shaped protrusion 221 during upsetting. Consequently, during the finish forging process, the amount of metal flowing downward in the preform blank 1 decreases. At the position where the upper ejector block 411 contacts the preform blank 1, i.e., the position where the spoke 51 is formed, no folding occurs. The formed spoke 51 part has greater strength, is not easily damaged, and is not prone to cracks, etc.

[0032] In the finish forging die 4, the taper θ3 of the lower outer periphery of the rim cavity 432 is also set according to the specific shape of the wheel hub. In the present invention, the taper θ1 of the tapered cavity 232 is controlled to be greater than the taper θ3 of the lower outer periphery of the rim cavity 433, such that during upsetting, the fluidity of the metal flow line of the blank 1 in the vertical direction is better. Thus, during finish forging, the metal flow line is more inclined to distribute along the outer contour in the vertical direction, achieving a reasonable conforming distribution of the metal flow line of the wheel hub forging 5, improving the load-bearing capacity of the wheel hub forging 5 and extending its fatigue life.

[0033] Furthermore, the diameter of the forging punch 41 is D2. The forging punch 41 is entirely inserted into the forging die 42 to forge the preform blank 1. When the top surface of the forging punch 41 is flush with the top surface of the forging die 42 after pressing down the forging punch 41 to the positioning point, even if the forging punch 41 is pressed down to the positioning point, a forging cavity 43 is formed between the forging punch 41 and the forging die 42. After forging is completed, the wheel hub forging 5 is obtained, and taking out the wheel hub forging 5 completes all steps.

[0034] In addition, in the finish forging die 4, between the upper and lower parts of the rim cavity 433, as well as at the transition positions between the rim cavity 433 and the rim cavity 432, there are arc-shaped transition surfaces that are concave outward. This is required by the shape of the wheel hub and also facilitates the metal flow of the preform blank 1, making the metal flow of the preform blank 1 smoother.

[0035] Comparative Example 1: The difference between this comparative example and Example 1 is that in Comparative Example 1, the blank 1 is directly placed into the finish forging die 4 for finish forging forming without performing the step of designing the preform blank 1. The wheel hub forging 5 produced is as Figure 6As shown, compared with the hub forging 5 obtained in the embodiment, the transition part between the spoke 51 and the rim 52 in Comparative Example 1 has folding, and the distribution of the partial metal streamline formed on the outer periphery of the top punch 411 is unreasonable and does not tend to be distributed along the outer contour of the hub forging 5. Moreover, the included angle α' between the direction of the metal streamline in the rim 53 part and the horizontal plane is greater than the included angle α in Example 1, and α in Example 1 tends to 0°. Therefore, in this part of Example 1, the metal streamline is basically distributed along the outer contour of the hub forging 5 in the radial direction, and the distribution is reasonable. However, in this part of Comparative Example 1, the metal streamline is not distributed along the outer contour of the hub forging 5 in the radial direction, and the distribution is unreasonable. Therefore, the present invention sets the step of designing the preform 1 to prevent folding and make the metal streamline reasonably distributed in the radial direction.

[0036] Comparative Example 2: The difference between this comparative example and Example 1 is that: in Example 1, the blank 1 with a height-diameter ratio of 1.3 is used for preparation, while in Comparative Example 2, the blank with a height-diameter ratio of 1.6 is used for preparation, and the other preparation steps are the same; Figure 7 is a folding schematic diagram of the hub forging 5 prepared in Example 1, Figure 8 is a folding schematic diagram of the hub forging 5 prepared in Comparative Example 1. By comparing Figure 7 and Figure 8 , it can be seen that there is folding at the transition position between the spoke 51 and the rim 52 in Comparative Example 1, and no folding occurs in Example 1. Thus, it can be proved that the larger the height-diameter ratio, the easier it is to produce folding. Therefore, the height-diameter ratio of the blank 1 selected in the present invention should be less than 1.6 and no folding will occur.

[0037] Comparative Example 3: The difference between this comparative example and Example 1 is that: in Example 1, R1 < R3 is controlled, while in Comparative Example 3, R1 > R3 is controlled, and the other preparation steps are the same; Fig. 9 is a folding schematic diagram of the hub forging 5 prepared in Comparative Example 3. By comparing Figure 7 and Fig. 9 , it can be seen that there is relatively serious folding at the transition position between the spoke 51 and the rim 52 in Comparative Example 3. Therefore, the present invention controls R1 < R3.

[0038] Comparative Example 4: The difference between this comparative example and Example 1 is that: in Example 1, R1 > R2 is controlled, while in Comparative Example 4, R1 < R2 is controlled, and the other preparation steps are the same; Fig.10 is a folding schematic diagram of the hub forging 5 prepared in Comparative Example 4. By comparing Figure 7 and Fig.10 , it can be seen that there is folding at the transition position between the spoke 51 and the rim 52 in Comparative Example 4. Therefore, the present invention controls R1 > R2. Combining Comparative Examples 3 and 4, controlling R2 < R1 < R3 can further prevent folding.

[0039] Comparative Example 5: The difference between this comparative example and Example 1 is that: in Example 1, θ1>θ3 is controlled, while in Comparative Example 5, θ1<θ3 is controlled, and the other preparation steps are the same; Fig.11 Fig. is the metal streamline distribution diagram of the hub forging 5 prepared in Comparative Example 5, Fig.12 Fig. is the metal streamline distribution diagram of the hub forging 5 prepared in Example 1. Comparing Fig.11 and Fig.12 , where Fig.11 the rim 52 part formed on the outer periphery of the upper punch block 411 is part A, and the rim 52 part formed on the outer periphery of the lower punch block 421 is part B. Comparing part A with Fig.11 part A' in Fig.11 , and comparing part B with

[0040] Comparative Example 6: The difference between this comparative example and Example 1 is that: in Example 1, the blank 1 with a height-diameter ratio of 1.3 is used for preparation, while in Comparative Example 2, the blank 1 with a height-diameter ratio of 0.9 is used for preparation, and the other preparation steps are the same; Fig.13 Fig. is the metal streamline distribution diagram of the hub forging 5 prepared in Comparative Example 6, Fig.14 Fig. is the metal streamline distribution diagram of the hub forging 5 prepared in Example 1. Comparing Fig.13 and Fig.14 the rim 53 parts in

[0041] The above is only the preferred embodiment of the present invention, and it is not a limitation to the design of this case. All equivalent changes made according to the key design of this case fall within the protection scope of this case.

Claims

1. A wheel hub extrusion forming method based on streamline control, characterized in that: It includes the following steps: S1. Design a blank with a reasonable height-diameter ratio: Prepare a cylindrical blank with a height of h and a diameter of d, where 0.9 < h / d < 1.6; S2. Preform design: Place the blank in a upsetting die for pre-upsetting to form a preform; The upsetting die includes an upsetting punch and an upsetting die cavity is formed between the upsetting punch and the upsetting die. The upper part of the upsetting die cavity is a cylindrical cavity with a diameter of D1. The lower part of the upsetting die cavity is an inverted conical cavity with a taper of θ1. In the middle of the bottom surface of the conical cavity, there is an upward convex arc-shaped protrusion with a fillet radius of R1; S3. Finish forging: Place the preform in a finish forging die for forging to form the final forged wheel hub; The finish forging die includes a forging punch and a forging die. In the middle of the bottom surface of the forging punch, there is a downward convex inverted conical upper ejector block with a taper of θ2. The bottom end of the upper ejector block is an arc-shaped end with a fillet radius of R2. Between the forging punch and the forging die, a forging die cavity is formed. In the middle of the bottom surface of the forging die cavity, there is an upward convex lower ejector block with an arc-shaped end at the top and a fillet radius of R3, where R2 < R1 < R3. The upper ejector block and the lower ejector block cooperate up and down to make the cross-section of the forged wheel hub in an H shape. A spoke die cavity is formed between the upper ejector block and the lower ejector block. The upper outer periphery of the upper ejector block forms a rim die cavity. The upper part of the rim die cavity is cylindrical with a diameter of D2, where d < D1 < D2. The lower part of the rim die cavity is an inverted conical shape with a taper of θ3, where θ3 < θ1 < θ2. The lower outer periphery of the upper ejector block and the outer periphery of the lower ejector block form a rim die cavity, and the diameter of the rim die cavity is smaller than the diameter of the rim die cavity.

2. A wheel hub extrusion forming method based on streamline control as claimed in claim 1, characterized in that: In step S1, 1.1 < h / d < 1.

3.

3. A wheel hub extrusion forming method based on streamline control as claimed in claim 1, characterized in that: In step S1, h / d = 1.

3.

4. A wheel hub extrusion forming method based on streamline control as claimed in claim 1, characterized in that: In step S2, the height of the cylindrical cavity is H1, and the height of the conical cavity is H2, H2 < H1.

5. The wheel hub extrusion forming method based on streamline control as claimed in claim 1, characterized in that: In step S3, the upper height of the rim die cavity is H3, and the sum of the lower height of the rim die cavity and the height of the rim die cavity is H4, H3 < H4.

6. The wheel hub extrusion forming method based on streamline control as claimed in claim 1, characterized in that: In step S2, in the middle of the bottom surface of the upsetting punch, a convex block is formed downward. The diameter of the convex block is D1. The convex block extends into the upsetting die to upset the blank. When the abutting plane on the bottom surface of the upsetting punch distributed on the outer periphery of the convex block abuts against the top surface of the upsetting die, the upsetting die cavity is formed between the upsetting punch and the upsetting die. The upsetting is completed to obtain the preform.

7. The wheel hub extrusion forming method based on streamline control as claimed in claim 1, characterized in that: In step S3, the diameter of the forging punch is D2. The forging punch extends into the forging die as a whole to forge the preform. When the top surface of the forging punch is flush with the top surface of the forging die by pressing down the forging punch, the forging die cavity is formed between the forging punch and the forging die. The forging is completed to obtain the forged wheel hub.

8. The wheel hub extrusion forming method based on streamline control as claimed in claim 1, characterized in that: In step S1, the blank is 7A04 aluminum alloy.

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