A double-hole stepped groove special-shaped part for an automobile chassis and a production process thereof

Abstract

The application relates to a production process of a double-inner-hole stepped groove special-shaped part for an automobile chassis, which comprises the following steps: S1, cutting; S2, shaping: feeding the blank into a die for extrusion, so that the end part of the blank forms an outer chamfer, and the cutting burrs are removed; S3, pre-molding: forming an intermediate boss at one end of the shaped blank; S4, positioning hole forming; S5, reverse extrusion inner hole forming: using an oil press to perform reverse extrusion on the blank along the positioning hole size, so that an inner hole is formed in the blank; S6, turning the outer diameter of the rod part; S7, turning the sealing groove; S8, heat treatment: performing quenching and tempering heat treatment on the product after the sealing groove is formed. The application effectively solves the technical problem of instability of straightness and cylindricity during special-shaped inner hole forming in the prior art, effectively disperses the concentrated stress generated by the deformation of the end face of the blank during the extrusion process, makes the material flow line more stable, and further improves the forming precision of the inner hole and the batch consistency of the product.

Description

Technical Field

[0001] This invention relates to the field of automotive parts processing technology, and more specifically, to a double-inner-hole stepped grooved irregular part for automotive chassis and its manufacturing process. Background Technology

[0002] With the diversification of automobiles, automotive differentials have undergone multi-dimensional changes, placing higher demands on the performance and precision of their key internal components. The plug piston connector (also known as the PTU plug) in an automotive differential is one of the core components of the differential's hydraulic system. It features a blind hole inside, which serves as the sliding cavity for the piston rod. This blind hole must ensure smooth sliding of the central piston rod without excessive play. Therefore, extremely high requirements are placed on the material properties, dimensional tolerances, and surface quality of the inner hole of this component—the material must be guaranteed not to deform or fail abnormally during long-term use, and the straightness and cylindricity of the central blind hole must be controlled within 0.03mm to effectively ensure small assembly clearances and a good fit between the cavity and the piston rod.

[0003] Currently, in existing technologies, the production of plug piston connectors with irregularly shaped inner holes typically employs direct turning of bar stock or casting followed by finishing. However, direct turning of bar stock results in low material utilization and low processing efficiency; casting, on the other hand, struggles to guarantee the dimensional accuracy and surface quality of the inner hole. More critically, in existing processes, the punch experiences uneven stress during the reverse extrusion process when forming irregularly shaped inner holes, leading to inconsistent material deformation of the billet in the extrusion direction. This results in unstable and uncontrollable key dimensional data for inner hole forming, making it difficult to consistently meet the stringent requirement of 0.03mm for straightness and cylindricity, resulting in a high scrap rate. Summary of the Invention

[0004] The present invention aims to solve the problem of the production process of automotive differential plug piston connectors, which is unable to stably control the forming accuracy of irregular inner holes and cannot simultaneously take into account material utilization and production efficiency in the existing technology.

[0005] To solve the above problems, the present invention provides a manufacturing process for a double-inner-hole stepped grooved irregular part for automobile chassis, including the following steps: S1, material cutting: cutting the material to obtain a blank of a preset length; S2. Shaping: The blank is fed into a mold for extrusion, so that its ends form an outer chamfer and the cutting burrs are removed; S3, Pre-forming: A central boss is formed at one end of the shaped billet; S4. Positioning hole forming: Form positioning holes of the required shape on the end face with the boss for positioning deep holes under reverse extrusion. S5. Reverse extrusion forming inner hole: Using a hydraulic press, the blank is reverse extruded along the size of the positioning hole to form an inner hole inside the blank; S6. Turning the outer diameter of the rod: The outer diameter of the rod of the blank is turned using CNC technology; S7. Turning sealing groove: After clamping and turning the rod part of the blank, the sealing groove is formed by turning the corresponding position on the blank using CNC technology. S8. Heat treatment: The product after forming the sealing groove is subjected to heat treatment.

[0006] The present invention provides a manufacturing process for a double-inner-hole stepped grooved irregular part for automobile chassis, which, compared with the prior art, has the following beneficial effects, but is not limited to: The manufacturing process of this automotive chassis double-inner-hole stepped grooved irregular part pre-forms a central boss at one end of the blank in step S3. This provides a precise pre-forming positioning reference for the positioning hole forming in step S4 and the inner hole forming in step S5, resulting in more uniform stress on the blank during back extrusion and significantly improved straightness and cylindricity of the formed inner hole. Simultaneously, the size and position of the central boss are determined based on the target thickness range of the bottom during back extrusion forming, ensuring that the bottom thickness of the blank after back extrusion falls precisely within the required range. This avoids problems such as reduced mold life or material waste caused by an excessively thin or thick bottom. Furthermore, the pre-formed central boss, in conjunction with the back extrusion forming process, provides a precise positioning reference for back extrusion, ensuring uniform stress on the blank during back extrusion. This effectively solves the technical problem of unstable straightness and cylindricity during irregular inner hole forming in existing technologies, enabling the straightness and cylindricity of the inner hole to be stably controlled within 0.03mm.

[0007] Furthermore, in step S1, the material is wire rod round steel, specifically 40Cr annealed wire. Using annealed 40Cr material for direct cold heading ensures that the material has good cold forming properties.

[0008] Further, step S2, the shaping step, specifically involves: feeding the blank into a shaping mold for extrusion, processing an outer chamfer at one end of the blank to eliminate cutting burrs; flipping the blank and feeding it into the next mold for extrusion to obtain an outer chamfer at the other end of the blank, eliminating cutting burrs at the other end.

[0009] Furthermore, the pre-molding in step S3 and the positioning hole forming in step S4 are both formed using a reverse extrusion process.

[0010] Furthermore, between step S4 and step S5, the following steps are also included: S4a. Annealing: Annealing process is used to eliminate the work hardening of the product caused by the cold heading process. S4b, Phosphating and Saponification Treatment: The annealed billet is subjected to phosphating and saponification treatment to form a phosphating and saponification lubricating layer on the surface of the billet. The phosphating and saponification layer can improve the stability of material flow in subsequent processes and extend the service life of the mold.

[0011] Furthermore, in step S5, the end face of the extrusion punch used for reverse extrusion is provided with a groove, the shape of which is matched with the shape of the end face of the blank. By setting a groove on the end face of the extrusion punch that matches the shape of the end face of the blank, the stress generated by the deformation of the end face of the blank can be effectively reduced during the extrusion process, making the material flow lines more stable and further improving the forming accuracy of the inner hole.

[0012] Furthermore, the extrusion punch has a first rounded corner at the forming edge of the inner hole contour, and a second rounded corner on the protruding part of the extrusion punch, with the radius of the second rounded corner being larger than the radius of the first rounded corner. This ensures that the material moves in the same direction when the blank is subjected to extrusion force. By using rounded corners of different radii at different locations, the material moves in the same direction and is free from anisotropic stress interference when the blank is subjected to extrusion force. This improves the anisotropic stress generated by inner hole deformation, ensuring that the product remains stable throughout long-term production.

[0013] Furthermore, in step S6, the tolerance of the outer diameter is ensured to be within 0.03mm when turning the outer diameter of the rod; in step S5, the cylindricity and straightness of the formed inner hole are both controlled within 0.03mm. Through the combined process of cold heading and CNC precision machining, high-precision control of key dimensions is achieved.

[0014] Furthermore, after step S7 and before step S8, the following step is also included: using a machining center to mill the sealing end face notch of the blank to complete the final forming of the sealing end face.

[0015] Furthermore, the heat treatment in step S8 includes a quenching process and a tempering process. The quenching process involves heating to 850±10℃, setting the carbon potential to 0.40±0.05%C, holding for 40 minutes, using oil quenching at 60±5℃, and slowly stirring the quenching oil. The tempering process involves heating to 580±10℃, holding for 90 minutes, and using nitrogen protection throughout the process.

[0016] This invention also provides a double-inner-hole stepped grooved irregular part for automotive chassis, comprising: a sealing end and a rod portion. The sealing end includes a sealing groove and a flange, and is disposed at one end of the rod portion. The rod portion has an inner hole, which is a flower-shaped blind hole. The cylindricity and straightness of the flower-shaped blind hole are both 0.03 mm. There is a boss inside the rod portion near the other end, and the boss is fixed inside the rod portion through the bottom plane of the hole. The bottom plane of the hole is 3 mm away from the end face of the port. This structure is produced through the above process: cold heading is performed directly from 40Cr annealed material to form a blank suitable for stamping, ensuring that the blind hole is pressed to the appropriate depth in one go, and the bottom thickness is exactly within the required size range. Then, the stamped product is surface-machined to remove excess and unstable orifice material, and the sealing groove is CNC machined. Finally, heat treatment is performed to enhance the various properties of the material, effectively ensuring that no abnormal deformation or failure will occur during long-term use. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the product of the present invention; Figure 2 This is a schematic diagram of the internal structure of the product of the present invention; Figure 3 This is a schematic diagram of the production process steps of the present invention. Figure 1 ; Figure 4 This is a schematic diagram of the production process steps of the present invention. Figure 2 ; Figure 5 This is a schematic diagram of the extrusion punch in step S5 of the present invention.

[0018] Explanation of reference numerals in the attached figures: 100. Sealing end; 110. Sealing groove; 120. Flange; 130. Rod; 140. Inner hole; 150. Boss; 160. Bottom plane of hole; 200. Blank; 300. Blank one; 310. Outer chamfer one; 400. Blank two; 410. Outer chamfer two; 500. Blank three; 510. Boss one; 600. Blank four; 610. Positioning hole; 700. Blank five; 800. Semi-finished product; 810. Inner hole; 900. Semi-finished product one; 1000. Semi-finished product two; 1010. Sealing groove; 1200. Extrusion punch; 1210. Groove; 1220. Second fillet; 1230. First fillet. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, specific embodiments of this application are described clearly and completely below with reference to the accompanying drawings. It should be understood that the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort will fall within the scope of protection of this application.

[0020] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the specification of this application is for the purpose of describing specific embodiments only and is not intended to limit this application; the terms "comprising," "including," "having," "containing," "comprise," etc., in the specification, claims, and accompanying drawings of this application are open-ended terms, indicating that a method comprises one or more steps, or an apparatus comprises one or more elements, but do not exclude the inclusion of other steps or elements. The terms "first," "second," etc., in the specification, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or primary / secondary relationship. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0021] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0022] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0023] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0024] This invention provides a manufacturing process for a double-inner-hole stepped grooved irregular-shaped part for automotive chassis, comprising the following steps: S1. Cutting: Cutting the material into blanks of a preset length; S2. Shaping: The blank is fed into a mold for extrusion, so that its ends form an outer chamfer and the cutting burrs are removed; S3, Pre-forming: A central boss is formed at one end of the shaped billet; S4. Positioning hole forming: Form positioning holes of the required shape on the end face with the boss for positioning deep holes under reverse extrusion. S5. Reverse extrusion forming inner hole: Using a hydraulic press, the blank is reverse extruded along the size of the positioning hole to form an inner hole inside the blank; S6. Turning the outer diameter of the rod: The outer diameter of the rod of the blank is turned using CNC technology; S7. Turning sealing groove: After clamping and turning the rod part of the blank, the sealing groove is formed by turning the corresponding position on the blank using CNC technology. S8. Heat treatment: The product after forming the sealing groove is subjected to heat treatment.

[0025] The present invention provides a manufacturing process for a double-inner-hole stepped grooved irregular part for automobile chassis, which, compared with the prior art, has the following beneficial effects, but is not limited to: The manufacturing process of this automotive chassis double-inner-hole stepped grooved irregular part pre-forms a central boss at one end of the blank in step S3. This provides a precise pre-forming positioning reference for the positioning hole forming in step S4 and the inner hole forming in step S5, resulting in more uniform stress on the blank during back extrusion and significantly improved straightness and cylindricity of the formed inner hole. Simultaneously, the size and position of the central boss are determined based on the target thickness range of the bottom during back extrusion forming, ensuring that the bottom thickness of the blank after back extrusion falls precisely within the required range. This avoids problems such as reduced mold life or material waste caused by an excessively thin or thick bottom. Furthermore, the pre-formed central boss, in conjunction with the back extrusion forming process, provides a precise positioning reference for back extrusion, ensuring uniform stress on the blank during back extrusion. This effectively solves the technical problem of unstable straightness and cylindricity during irregular inner hole forming in existing technologies, enabling the straightness and cylindricity of the inner hole to be stably controlled within 0.03mm.

[0026] Specifically, such as Figure 3 As shown, step S1 corresponds to Figure 3 In step 1, 40Cr annealed wire rod is selected as the raw material. The wire is fed into a cold heading machine, and the cutting mechanism of the cold heading machine cuts the wire rod into blanks of the required length of 200 mm. 40Cr annealed material has good cold forming performance. Its annealed structure is uniform and its hardness is moderate, which is suitable for subsequent cold heading forming processing and can effectively avoid defects such as cracking during the cold heading process.

[0027] In this embodiment, the shaping step S2 specifically includes: Figure 3 Steps 2a and 2b are as follows: Step 2a (shaping 1): The cut blank 200 is fed into the shaping mold of the cold heading machine to form an outer chamfer 310, eliminate the burrs of the cut material, and obtain blank 300.

[0028] Step 2b (Shaping 2): After flipping the blank 300, it is sent into the next shaping mold to form the outer chamfer 410, and the shearing burrs on the other end are eliminated to obtain blank 400.

[0029] After two shaping processes, both ends of the billet 2400 have uniform external chamfers, flat end faces, and no shear burrs, providing a good billet shape foundation for subsequent pre-forming and reverse extrusion processes.

[0030] In this embodiment, both the pre-molding in step S3 and the positioning hole forming in step S4 are performed using a reverse extrusion process. Step S3 corresponds to... Figure 3 Step 3 specifically involves forming a boss 510 at the center of one end face of billet 400 using a reverse extrusion process, resulting in billet 500. The dimensions (diameter and height) and position of this intermediate boss 510 are designed and determined based on the target thickness range of the billet bottom after the subsequent reverse extrusion forming of the inner hole. The function of this intermediate boss 510 is to provide a pre-forming positioning reference for the subsequent reverse extrusion drilling process. Steps S1, S2, and S3 are completed sequentially in a cold heading machine using multi-station molds. The material is first cut to a preset length by a cutting mechanism, and then sequentially fed into the forming mold and pre-forming mold for processing. This achieves continuous and automated production of cutting → forming → pre-forming, reducing material transfer time and labor costs between processes and significantly improving production efficiency.

[0031] Step S4 corresponds to Figure 3 Step 4 specifically involves using a reverse extrusion process to form a positioning hole 610 of the required shape on one end face of the blank 3 500, which has a central boss 510, for positioning the deep hole during reverse extrusion, thus obtaining blank 4 600. This positioning hole 610 is used for precise positioning of the blank in the subsequent hydraulic press reverse extrusion forming inner hole process in step 5. The shape of the positioning hole 610 matches the positioning pin on the hydraulic press worktable.

[0032] In this embodiment, the following step is further included between step S4 and step S5: S4a, Annealing: Annealing is used to eliminate the work hardening caused by the cold heading process; corresponding to... Figure 4 In step 4a, due to the significant plastic deformation of the billet during cold heading, a large number of dislocations and internal stresses are generated inside the material, leading to increased hardness and strength but decreased plasticity. Annealing reduces the dislocation density inside the material, causing grain recovery and recrystallization, restoring it to a state of lower hardness and higher plasticity. This provides good material plastic deformation capability for the subsequent reverse extrusion forming of the inner hole, ensuring that the material can flow uniformly and smoothly during the reverse extrusion forming process.

[0033] S4b, Phosphating and Saponification Treatment: The annealed billet is subjected to phosphating and saponification treatment to form a phosphating and saponification lubricating layer on the surface of the billet; corresponding to... Figure 4 Step 4b utilizes a phosphating and saponification process to enhance the lubrication of the billet surface. The annealed billet undergoes phosphating and saponification to form a billet with a phosphating and saponification layer on its surface (e.g., 5700), resulting in more stable subsequent forming processes and improved die life. The function of this lubricating layer is to reduce the coefficient of friction between the billet and the cutting tool / die during subsequent reverse extrusion forming of the inner hole, CNC turning, and final surface treatment, thereby improving the uniformity and stability of material flow and extending the service life of the cutting tool and die. The billet surface after phosphating and saponification is grayish-black and has a lubricated texture.

[0034] In this embodiment, step S5 corresponds to Figure 4 Step 5 specifically involves placing the blank 700 into a hydraulic press. The hydraulic press drives the extrusion punch downwards, applying extrusion pressure to the end face of the blank 700. A reverse extrusion process is used to form a patterned inner hole 810 inside the blank 700, resulting in a semi-finished product 800. During the reverse extrusion process, the material flows axially downwards and radially outwards under the action of the extrusion punch. Simultaneously, a bottom boss and a bottom surface are formed at the bottom of the blank while the inner hole is being formed.

[0035] In this step, the billet is positioned using the intermediate boss 510 as a datum, ensuring that the central axis of the billet is coaxial with the axis of the extrusion punch during reverse extrusion. The size and position of the intermediate boss 510 are determined based on the target thickness range of the bottom during reverse extrusion forming, so that after reverse extrusion in step 5, the bottom thickness of the billet is exactly within the target size range. This ensures that the bottom has sufficient structural strength to prevent deformation or cracking during subsequent use, while also avoiding material waste caused by excessive bottom thickness. The extrusion punch structure used in this step is as follows: Figure 5As shown, specifically: the end face of the extrusion punch 1200 is provided with a groove 1210, the shape of which matches the shape of the end face of the blank. During the extrusion process, the fit between the groove 1210 and the end face of the blank can effectively disperse the concentrated stress generated by the end face deformation, making the material flow line more stable and avoiding deviations in the straightness of the inner hole forming due to end face stress concentration. The forming corner of the extrusion punch used to form the inner hole contour is provided with a first rounded corner 1230, and the protruding part of the extrusion punch is provided with a second rounded corner 1220, and the radius of the second rounded corner 1220 is larger than the radius of the first rounded corner 1230, so that the material moves in the same direction when the blank is subjected to extrusion force. During the reverse extrusion process, the smaller radius of the first rounded corner 1230 can ensure the clear forming of the inner hole contour pattern, while the larger radius of the second rounded corner 1220 can guide the smooth flow of material at the protruding part. When the billet is subjected to extrusion pressure, due to the differentiated design of the fillet radius in different parts, the material moves in the same direction along the extrusion direction without significant anisotropic stress interference. This improves the anisotropic stress problem caused by the deformation of the inner hole, so that the straightness and cylindricity of the inner hole of the product tend to be stable during long-term production and can continuously meet the accuracy requirements within 0.03mm.

[0036] In this embodiment, step S6 corresponds to step 6 in the figure, specifically involving clamping the phosphated and saponified billet onto a CNC lathe and machining the outer diameter of the rod portion using CNC technology. The tolerance of the outer diameter of the rod portion after machining is controlled within 0.03mm, yielding a semi-finished product -900. High-precision control of the rod portion's outer diameter is crucial for ensuring the assembly accuracy and sealing performance of the plug piston in the differential.

[0037] Step S7 corresponds to step 7 in the figure. Specifically, it involves clamping and turning the outer diameter of the rod portion of the semi-finished product 1000 after machining, and then using a CNC lathe to machine the sealing groove 1010 at the corresponding position on the blank to obtain the semi-finished product 1000. The sealing groove 1010 is used to install the sealing ring, so its dimensional accuracy and surface roughness have strict requirements to ensure that the sealing ring can achieve reliable static and dynamic sealing effects after installation.

[0038] In this embodiment, after step S7 and before step S8, the following step is also included: milling the sealing end face notch of the blank using a machining center, i.e. Figure 4 Step 7a involves using a machining center to mill a notch into the sealing end face of the blank, thus completing the final forming of the sealing end face. The specific shape and size of the sealing end face notch are determined according to the assembly interface requirements of the differential hydraulic system.

[0039] The product after completing all the above machining processes undergoes quenching and tempering heat treatment. The specific process is as follows: the heat treatment in step S8 includes quenching and tempering. The quenching process involves heating to 850±10℃, a carbon potential of 0.40±0.05%C, holding for 40 minutes, and oil quenching at 60±5℃ with slow stirring of the quenching oil. The tempering process involves heating to 580±10℃, holding for 90 minutes, and providing nitrogen protection throughout. This effectively prevents workpiece deformation and delayed cracking, significantly improves the material's plasticity and impact toughness, achieving a good balance between strength and toughness, and possessing excellent comprehensive mechanical properties. Parts treated with this process can reliably withstand alternating loads, impact loads, and complex torsional stresses, and are widely applicable to the performance requirements of key transmission components such as gears, connecting rods, and shafts.

[0040] The mechanism by which this embodiment solves the technical problem is as follows: By designing a process route of pre-formed intermediate boss → reverse extrusion forming of the inner hole, the intermediate boss provides a precise positioning reference for reverse extrusion, solving the problem of unstable straightness during the forming of irregularly shaped inner holes; by setting a groove on the end face of the extrusion punch to fit the shape of the blank, the end face deformation stress is reduced, further improving the stability of the inner hole straightness; by differentially setting fillets of different radii on the extrusion punch, the material flow direction is made consistent, eliminating the interference of anisotropic stress on the accuracy of the inner hole; by designing the size of the pre-formed intermediate boss to control the bottom thickness, the problem of low mold life when the bottom is too thin is improved. The entire process mainly uses cold heading forming and supplemented by CNC precision machining, with high material utilization and suitable for mass automated production.

[0041] Another embodiment of the present invention is a double-inner-hole stepped grooved irregular part for automobile chassis, which is also a differential plug piston for automobiles, processed using the above-described process. Figure 1 and Figure 2 As shown, it includes a sealing end 100 and a rod portion 130. The sealing end 100 includes a sealing groove 110 and a flange 120. One end of the rod portion 130 is located at the sealing end 100. The rod portion 130 has an inner hole 140, which is a flower-shaped blind hole with a cylindricity and straightness of 0.03 mm. A boss 150 is located inside the rod portion 130 near the other end. The boss 150 is fixed inside the rod portion 130 by a bottom plane 160, which is 3 mm away from the end face of the port. This automotive differential plug piston has high precision, effectively ensuring that it will not deform or fail during long-term use.

[0042] In other embodiments, the material of the wire rod round steel in step S1 can be, in addition to the aforementioned 40Cr annealed wire rod, other medium carbon alloy steel materials with good cold forming and heat treatment properties, such as 42CrMo, 35CrMo, etc., as long as it has sufficient cold forming plasticity in the annealed state and can meet the mechanical property requirements of the product after quenching and tempering.

[0043] In other embodiments, the heat treatment process parameters in step S8 can be appropriately adjusted according to the specific dimensions of the product, the furnace loading, and the heat treatment characteristics of different materials. The quenching medium can also be water-based or polymer-based quenching fluid instead of pure oil quenching, depending on the actual situation.

[0044] In other embodiments, the radius values ​​of the first fillet 1230 and the second fillet 1220 of the extrusion punch in step S5 are optimized based on the geometry of the inner hole 810 pattern and the material flow characteristics to ensure the best balance between the inner hole forming accuracy and the material flow stability.

[0045] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A manufacturing process for a double-inner-hole stepped grooved irregular-shaped part for automobile chassis, characterized in that, Includes the following steps: S1. Cutting: Cutting the material into blanks of a preset length; S2. Shaping: The blank is fed into a mold for extrusion, so that its ends form an outer chamfer and the cutting burrs are removed; S3, Pre-forming: A central boss is formed at one end of the shaped billet; S4. Positioning hole forming: Form positioning holes of the required shape on the end face with the boss for positioning deep holes under reverse extrusion. S5. Reverse extrusion forming inner hole: Using a hydraulic press, the blank is reverse extruded along the size of the positioning hole to form an inner hole inside the blank; S6. Turning the outer diameter of the rod: The outer diameter of the rod of the blank is turned using CNC technology; S7. Turning sealing groove: After clamping and turning the rod part of the blank, the sealing groove is formed by turning the corresponding position on the blank using CNC technology. S8. Heat treatment: The product after forming the sealing groove is subjected to heat treatment.

2. The manufacturing process of the double-inner-hole stepped grooved irregular part for automobile chassis according to claim 1, characterized in that, In step S1, the material is wire rod round steel, and the material is 40Cr annealed wire.

3. The manufacturing process of the double-inner-hole stepped grooved irregular part for automobile chassis according to claim 1, characterized in that, Step S2, the shaping step, is as follows: the blank is fed into the shaping mold for extrusion, and an outer chamfer is processed on one end of the blank to eliminate the cutting burrs; the blank is flipped over and fed into the next mold for extrusion so that the other end of the blank has an outer chamfer to eliminate the cutting burrs on the other end; the pre-shaping in step S3 and the positioning hole forming in step S4 are both formed by reverse extrusion process.

4. The manufacturing process of the double-inner-hole stepped grooved irregular part for automobile chassis according to claim 1, characterized in that, Between step S4 and step S5, the following steps are also included: S4a. Annealing: Annealing process is used to eliminate the work hardening of the product caused by the cold heading process. S4b, Phosphating and Saponification Treatment: The annealed billet is subjected to phosphating and saponification treatment to form a phosphating and saponification lubricating layer on the surface of the billet.

5. The manufacturing process of the double-inner-hole stepped grooved irregular part for automobile chassis according to claim 1, characterized in that, In step S5, the end face of the extrusion punch (1200) used for reverse extrusion is provided with a groove (1210), the shape of the groove (1210) is matched with the shape of the end face of the blank, the extrusion punch is provided with a first rounded corner (1230) at the forming corner of the inner hole contour, and the protruding part of the extrusion punch is provided with a second rounded corner (1220), and the radius of the second rounded corner (1220) is greater than the radius of the first rounded corner (1230), so that the material moves in the same direction when the blank is subjected to extrusion force.

6. The manufacturing process of the double-inner-hole stepped grooved irregular part for automobile chassis according to claim 1, characterized in that, In step S6, when turning the outer diameter of the rod, the tolerance of the outer circle is ensured to be within 0.03mm; in step S5, the cylindricity and straightness of the formed inner hole are both controlled to be within 0.03mm.

7. The manufacturing process of the double-inner-hole stepped grooved irregular part for automobile chassis according to claim 1, characterized in that, After step S7 and before step S8, the following step is also included: milling the sealing end face notch of the blank using a machining center.

8. The manufacturing process of the double-inner-hole stepped grooved irregular part for automobile chassis according to claim 1, characterized in that, The heat treatment in step S8 includes a quenching process and a tempering process. The quenching process involves heating to 850±10℃, carbon potential 0.40±0.05%C, holding for 40 minutes, and then oil quenching at 60±5℃ with slow stirring of the quenching oil. The tempering process involves heating to 580±10℃, holding for 90 minutes, and providing nitrogen protection throughout the process.

9. A double-inner-hole stepped grooved irregular-shaped part for automobile chassis, characterized in that, include: The sealing end (100) and the rod (130) are provided. The sealing end (100) includes a sealing groove (110) and a flange (120). The sealing end (100) is located at one end of the rod (130). The rod (130) is provided with an inner hole (140). The inner hole (140) is a flower-shaped blind hole. There is a boss (150) inside the rod (130) near the other end. The boss (150) is fixed inside the rod (130) through the bottom plane (160) of the hole.

10. The double-inner-hole stepped grooved irregular-shaped part for automobile chassis according to claim 9, characterized in that, The cylindricity and straightness of the flower-shaped blind hole are both 0.03 mm, and the bottom plane (160) of the hole is 3 mm away from the end face of the port.

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