Cold heading process for mandrel sleeve of automotive suspension steering knuckle

Abstract

The invention relates to the field of steering knuckle mandrel sleeve machining, and discloses a cold heading process of an automotive suspension steering knuckle mandrel sleeve, which comprises the following steps: selecting high-plasticity and low-hardness steel material for cutting to obtain a bar material I; the first bar is put into a mold to be subjected to preliminary upsetting, a second bar is obtained, and a first chamfering head is formed at the bottom of the second bar; the second bar is turned over, the first chamfering head is arranged upwards, the second bar is upset, a second chamfering head is formed on the side, opposite to the first chamfering head, of the second bar, a first hole groove is formed in one side of the first chamfering head of the second bar, and a third bar is obtained; and the third bar is turned over, the second chamfering head is arranged upwards, and cold heading hole pressing is conducted on the first hole groove of the third bar. The cold heading process is adopted, the plasticity of the steel is utilized for gradual forming in the die, the initial bar is subjected to multiple cold heading procedures, the material is always fully utilized within the plastic deformation range, waste materials are reduced, the production cost is effectively reduced, and the utilization efficiency of resources is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of knuckle spindle bushing processing, and particularly to a cold heading process for an automotive suspension knuckle spindle bushing. Background Art

[0002] As an important part of modern manufacturing, the automotive industry has developed rapidly, and the requirements for the performance, quality, and production efficiency of automotive parts are increasing day by day. The automotive suspension knuckle spindle bushing, as a key component of the automotive suspension system, directly affects the handling stability, driving safety, and riding comfort of the vehicle. In the field of parts manufacturing, advanced manufacturing processes have emerged continuously, aiming to improve product quality, reduce production costs, and reduce energy consumption and environmental pollution. As an efficient plastic forming processing method, the cold heading process has been widely used in the manufacturing of automotive parts. It applies pressure to a metal blank at room temperature to cause plastic deformation, thereby obtaining the required shape and size, and has the advantages of high production efficiency, high material utilization rate, and high product precision, meeting the development trend of modern manufacturing.

[0003] In the processing field of automotive suspension knuckle spindle bushings, cutting processing is generally adopted. It uses cutting tools to gradually remove metal materials to achieve the required shape and size. When processing the knuckle spindle bushing, the raw material is usually processed into a rough shape first, and then fine cutting processing is carried out to meet the requirements of dimensional accuracy and surface quality. For example, turning, milling, drilling and other operations are carried out using equipment such as lathes, milling machines, and drilling machines. The advantages of this process are relatively high processing accuracy, the ability to meet relatively complex shape requirements, and easy control of the processing process, having a certain degree of flexibility for small batch production.

[0004] However, when the traditional processing process is used to process the spindle bushing, a large amount of metal chips will be generated. These chips cannot be reused for part forming, resulting in serious material waste, increasing production costs, and also not conforming to the environmental protection concept of resource conservation. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a cold heading process for an automotive suspension knuckle spindle bushing, which solves the problem of low material utilization rate when the traditional processing process is used to process the spindle bushing.

[0006] To achieve the above objectives, the present invention is realized through the following technical solutions: A cold heading process for an automotive suspension knuckle spindle bushing includes the following steps: S1. Select steel with high plasticity and low hardness for cutting to obtain bar one; S2. Place bar one into a mold for preliminary upsetting to obtain bar two, and form a chamfer head one at the bottom of bar two; S3. Flip the second bar so that the first chamfering head is set upward, upset the second bar to form a second chamfering head on the side opposite to the first chamfering head of the second bar, and form a first hole groove on one side of the first chamfering head of the second bar to obtain the third bar; S4. Flip the third bar so that the second chamfering head is set upward, cold upset and punch the first hole groove of the third bar to form a first punched hole, and form a second hole groove on one side of the second chamfering head of the third bar to obtain the fourth bar; S5. Cold upset and punch the second hole groove of the fourth bar to form a second punched hole, and change the diameter of the first punched hole to obtain the fifth bar; S6. Cold upset the fifth bar along the first punched hole and the second punched hole to remove the residual material between the first punched hole and the second punched hole, and obtain a bar with an inner hole, namely the sixth bar; S7. Cold upset and form the sixth bar, and then carry out trimming, annealing and surface treatment to obtain the core shaft sleeve.

[0007] Preferably, in S1, the elongation rate of the steel with high plasticity and low hardness is ≥25%, the Brinell hardness is ≤180 HB, including carbon steel and stainless steel, and the diameter of the first bar is 22.6 mm and the length is 47 mm;

[0008] Preferably, in S2, the diameter of the second bar is 22.73 mm and the length is 46.5 mm, and the angle of the first chamfering head is 150°;

[0009] Preferably, in S3, the diameter of the third bar is 22.83 mm and the length is 47 mm, the angle of the second chamfering head is 160°, and the diameter of the first hole groove is 12.79 mm;

[0010] Preferably, in S4, the diameter of the first punched hole is 12.75 mm and the depth is 30 mm, the diameter of the second hole groove is 12.79 mm, and the diameter of the fourth bar is 22.89 mm and the length is 55.90 mm;

[0011] Preferably, in S5, the diameter of the second punched hole is 12.75 mm and the depth is 30 mm, and the diameter of the first punched hole becomes 12.7 mm;

[0012] Preferably, in S5, the diameter of the fifth bar is 22.95 mm and the length is 64 mm, and in S6, the inner hole diameter of the sixth bar is 12.7 mm and the length is 64 mm;

[0013] Preferably, in S7, the outer diameter of the core shaft sleeve is 23 mm, the inner hole diameter is 12.65 mm, and the length is 64 mm;

[0014] Preferably, in S7, the trimming includes removing the burrs and flash on the surface of the sixth bar, and precisely trimming the dimensions of the sixth bar according to the designed dimensional tolerance range, including the outer diameter and the length.

[0015] Preferably, the annealing temperature in S7 is 600 - 700 °C, and the heat preservation time is 1 - 2 hours. The surface treatment includes galvanizing and phosphating treatment.

[0016] The present invention provides a cold heading process for an automotive suspension steering knuckle spindle sleeve, having the following beneficial effects: 1. By adopting the cold heading process, the present invention gradually forms the steel in the mold by utilizing the plasticity of the steel. Starting from the initial bar, through multiple cold heading processes, the material is always fully utilized within the plastic deformation range, reducing waste generation, effectively reducing production costs, and improving the utilization efficiency of resources.

[0017] 2. Since the processing process of the present invention is carried out at room temperature, it avoids the thermal deformation and surface oxidation caused by high temperature in the hot forging process. Moreover, the dimensional changes of the bar at each stage, the chamfer head angle, the dimensional accuracy of the hole groove and the press hole, etc. can all be accurately controlled to meet the high standards of automotive suspension requirements, ensuring the high precision of the product, and improving the assembly accuracy and overall performance of the spindle sleeve and other components.

[0018] 3. Through the cold heading process, the internal organizational structure of the steel becomes more dense and uniform during the plastic deformation process. After being processed through multiple cold heading processes, the microstructure of the spindle sleeve is optimized, and the dislocation density increases, thereby improving the strength and hardness of the material. When the produced product bears the same external force, it has better mechanical properties, can effectively improve the reliability and service life of the automotive suspension steering knuckle, and ensure the safety of vehicle driving.

[0019] 4. By adopting the cold heading process, on the one hand, the high material utilization rate reduces the waste of raw materials and the raw material cost. On the other hand, the cold heading process has a high production efficiency and is faster than cutting processing, which can shorten the production cycle. At the same time, it avoids the large amount of energy consumption required for high-temperature heating in the hot forging process and additional costs such as subsequent treatment of scale, saving costs in multiple aspects such as raw materials, energy, and production time, and improving the economic benefits of the enterprise.

[0020] 5. By adopting the cold heading process, the present invention reduces the solid waste pollution to the environment caused by waste generation, and does not require high-temperature heating, reducing energy consumption and greenhouse gas emissions, and avoiding a large amount of scale pollution caused by high-temperature oxidation, which is more in line with the concept of sustainable development and helps to promote the green development of the automotive parts manufacturing industry. Brief Description of the Drawings

[0021] Figure 1 is a process flow chart of a cold heading process for an automotive suspension steering knuckle spindle sleeve proposed by the present invention; Figure 2 is a partial structural schematic diagram of the bar of the present invention; Figure 3 Schematic diagram of the partial structure of the second bar of the present invention; Figure 4 Schematic diagram of the partial structure of the third bar of the present invention; Figure 5 Schematic diagram of the partial structure of the fourth bar of the present invention; Figure 6 Schematic diagram of the partial structure of the fifth bar of the present invention; Figure 7 Schematic diagram of the partial structure of the sixth bar of the present invention.

[0022] Among them, 1. Chamfer head one; 2. Chamfer head two; 3. Hole groove one; 4. Press hole one; 5. Hole groove two; 6. Press hole two; 7. Inner hole. Specific embodiments

[0023] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0024] Please refer to the attached Figure 1 - attached Figure 2 , the embodiment of the present invention provides a cold heading process for an automotive suspension steering knuckle spindle sleeve, including the following steps: S1. Select high-plasticity and low-hardness steel for cutting to obtain the first bar; in S1, the elongation rate of the high-plasticity and low-hardness steel is ≥25%, the Brinell hardness is ≤180 HB, including carbon steel and stainless steel, and the diameter of the first bar is 22.6 mm and the length is 47 mm.

[0025] Specifically, in actual production, the selection of steel needs to consider various factors comprehensively. The reason for selecting steel with an elongation rate ≥25% and a Brinell hardness ≤180 HB is that such steel can better undergo plastic deformation during cold heading, reducing material cracking and defects. Carbon steel and stainless steel have good comprehensive properties, low cost and are easy to process, making them suitable as raw materials for automotive suspension steering knuckle spindle sleeves. Carbon steel, due to its good workability and moderate cost, has become a commonly used basic material. Stainless steel, on the other hand, has excellent corrosion resistance, which can meet the use requirements of automobiles in complex environments. Taking 20# carbon steel as an example, its carbon content is about 0.2%, and this low carbon content gives it high plasticity, effectively reducing the cracking risk during cold heading.

[0026] In the material cutting process, numerical control cutting equipment such as laser cutting machines or high-precision band saws is used to avoid affecting subsequent processing due to dimensional deviations. Laser cutting machines use laser beams with high energy density to melt or vaporize the material to be cut, featuring high cutting precision and narrow cut edges. Before cutting, according to the dimensional requirements of bar one, cutting parameters including cutting speed, laser power, etc. need to be accurately input into the equipment control system. At the same time, to ensure cutting quality, the flow rate and pressure of cutting gases such as oxygen and nitrogen also need to be reasonably adjusted. For example, when using oxygen as the cutting gas, its flow rate is generally controlled at 5 - 8 L / min, and the pressure is maintained at 0.5 - 0.8 MPa, which can ensure a smooth cutting surface and reduce the heat-affected zone.

[0027] S2. Place bar one into the mold and perform preliminary upsetting to obtain bar two, and form a chamfer head one 1 at the bottom of bar two; in S2, the diameter of bar two is 22.73 mm, the length is 46.5 mm, and the angle of chamfer head one 1 is 150°.

[0028] Specifically, a cold upsetting press is selected as the upsetting equipment, which has high pressure output and precise stroke control capabilities. Before upsetting, the mold needs to be preheated, and the preheating temperature is controlled at 80 - 100 °C, which helps to improve the fluidity of the steel and reduce the frictional resistance during the upsetting process. The mold is made of high-strength alloy steel, and through precision machining and heat treatment, the wear resistance and dimensional stability of the mold under high pressure can be ensured.

[0029] During the upsetting process, an axial pressure is applied to bar one using the press, and the pressure magnitude is adjusted according to the characteristics of the steel and the design of the mold. The pressure of the press gradually increases, with the initial pressure set at 80 - 100 tons, and as the upsetting progresses, the pressure slowly rises to 120 - 150 tons. At the same time, the slider speed of the press is controlled at 5 - 8 mm / s, which can not only ensure sufficient deformation of the steel but also avoid uneven deformation caused by too fast speed. In the design of the mold, the chamfer head one 1 at the bottom is formed by a specific mold cavity structure. The 150° chamfer angle can make the bar be placed more stably in the mold during subsequent processing, and during the upsetting process, the material can flow evenly along the chamfer, effectively reducing the stress concentration phenomenon and improving the internal quality of the product.

[0030] S3. Flip bar two so that chamfer head one 1 is set upward, and upset bar two to form a chamfer head two 2 on the side opposite to chamfer head one 1 of bar two, and form a hole groove one 3 on one side of chamfer head one 1 of bar two to obtain bar three; in S3, the diameter of bar three is 22.83 mm, the length is 47 mm, the angle of chamfer head two 2 is 160°, and the diameter of hole groove one 3 is 12.79 mm.

[0031] Specifically, after turning the second bar stock over and upsetting it again, it is to further shape the product and at the same time form a symmetrical chamfer structure. When upsetting again, the parameters of the press need to be adjusted according to the size and deformation of the second bar stock. The pressure is set at 150 - 180 tons, and the slider speed is maintained at 4 - 6 mm / s. The part of the die for forming the first hole groove 3 adopts a replaceable insert structure, and the insert is made of cemented carbide to ensure the dimensional stability of the first hole groove 3 during multiple upsetting processes.

[0032] During the upsetting process, the formation of the first hole groove 3 is achieved by the protruding part on the die extruding the steel, which provides a basis for the subsequent hole pressing process. To ensure the diameter accuracy of the first hole groove 3, during the die manufacturing process, the dimensional accuracy of the protruding part is controlled within ±0.01 mm. The second chamfer head 2 with an angle of 160° and the first chamfer head 1 with an angle of 150° cooperate with each other, enabling the bar stock to be better positioned and balanced during subsequent processing, and ensuring the stability of the product during subsequent processing.

[0033] S4. Turn the third bar stock over so that the second chamfer head 2 is set upward, perform cold upsetting hole pressing on the first hole groove 3 of the third bar stock to form the first pressed hole 4, and form the second hole groove 5 on one side of the second chamfer head 2 of the third bar stock to obtain the fourth bar stock; in S4, the diameter of the first pressed hole 4 is 12.75 mm, the depth is 30 mm, the diameter of the second hole groove 5 is 12.79 mm, the diameter of the fourth bar stock is 22.89 mm, and the length is 55.90 mm.

[0034] Specifically, before hole pressing with a cold upsetting hole press, lubricate the hole - pressing punch, use a lubricant containing molybdenum disulfide to form a uniform lubricating film on the surface of the punch, reduce the friction coefficient between the punch and the steel, reduce the wear of the punch, and at the same time help improve the surface quality of the hole pressing. The pressure of the hole press is adjusted according to requirements to ensure that the depth of the first pressed hole 4 is 30 mm. During the hole - pressing process, the material of the third bar stock undergoes plastic flow under pressure to form the second hole groove 5 on one side of the second chamfer head 2. At the same time, monitor the temperature during the hole - pressing process. Since a certain amount of heat is generated during the cold upsetting hole - pressing process, when the temperature exceeds 50 °C, the processing needs to be paused to cool the die and the bar stock to avoid changes in the properties of the steel and dimensional deviations caused by excessive temperature.

[0035] S5. Perform cold upsetting hole pressing on the second hole groove 5 of the fourth bar stock to form the second pressed hole 6, and change the diameter of the first pressed hole 4 to obtain the fifth bar stock; in S5, the diameter of the second pressed hole 6 is 12.75 mm, the depth is 30 mm, and the diameter of the first pressed hole 4 becomes 12.7 mm.

[0036] Specifically, to ensure the quality of the second punching hole 6, the mold and the punch are inspected and adjusted again before punching. The surface of the mold is cleaned and lubricated to ensure that the punch can smoothly enter the second hole groove 5. During the punching process, the pressure of the press is controlled according to requirements, so that the depth of the second punching hole 6 reaches 30 mm and the diameter is 12.75 mm. During the forming process of the second punching hole 6, the diameter of the first punching hole 4 will change due to the flow of the material. To control the final diameter of the first punching hole 4, during the mold design and processing, the deformation law of the material is fully considered, and the structure and size of the mold are optimized. During the production process, every 5 - 10 products are completed, the diameter of the first punching hole 4 is detected. Once it is found that the diameter deviation exceeds ±0.02 mm, the mold and the punching process parameters are immediately adjusted to ensure the stability of the product quality. By cold heading and punching the second hole groove 5, a second punching hole 6 corresponding to the first punching hole 4 is formed. The two punching holes cooperate with each other to make the inner hole 7 more regular, and further precise the size and shape of the inner hole 7.

[0037] S6. Cold heading the fifth bar along the first punching hole 4 and the second punching hole 6, removing the residual material between the first punching hole 4 and the second punching hole 6, and obtaining the sixth bar with the inner hole 7; the diameter of the fifth bar in S5 is 22.95 mm and the length is 64 mm, and the diameter of the inner hole 7 of the sixth bar in S6 is 12.7 mm and the length is 64 mm.

[0038] Specifically, a cold heading die and a punch are used to remove the residual material. The excess material between the first punching hole 4 and the second punching hole 6 is removed by cold heading. Before cold heading processing, the die and the punch are preheated, and the preheating temperature is controlled at 60 - 80 °C to improve the plasticity of the material and reduce the cracking risk during cold heading. The pressure of the cold heading press is set at 180 - 220 tons, and the residual material is gradually removed by multiple impacts. During the process of removing the residual material, closely monitor the working state of the punch to prevent the punch from being damaged due to uneven stress. At the same time, the inner hole 7 of the sixth bar is detected in real time to ensure that the diameter and length of the inner hole 7 meet the design requirements. Every 20 - 30 products are completed, the die and the punch are inspected and maintained, and the worn parts are replaced in time to ensure the effect of removing the residual material and the product quality. The obtained sixth bar has a complete inner hole 7, and its diameter and length meet the design requirements of the mandrel sleeve.

[0039] S7. Cold heading the sixth bar to form it, and then carrying out trimming, annealing and surface treatment to obtain the mandrel sleeve. The outer diameter of the mandrel sleeve in S7 is 23 mm, the diameter of the inner hole 7 is 12.65 mm, and the length is 64 mm. The trimming in S7 includes removing the burrs and flash on the surface of the sixth bar, and precisely trimming the dimensions of the sixth bar, including the outer diameter and length, according to the designed dimensional tolerance range. The temperature of the annealing treatment in S7 is 600 - 700 °C, and the holding time is 1 - 2 hours. The surface treatment includes galvanizing and phosphating treatment.

[0040] Specifically, a high-precision cold heading die is used in the cold heading forming process. During the cold heading forming process, the pressure and stroke of the press need to be precisely controlled. The pressure is set at 200 - 250 tons. Through cold heading forming, the outer diameter of bar six reaches 23 mm, the diameter of inner hole 7 is further precisely controlled to 12.65 mm, and the length remains 64 mm, meeting the design requirements. In the trimming process, a combination of machining and manual grinding is adopted. First, a CNC lathe is used to perform finish turning on the outer diameter of bar six, controlling the outer diameter tolerance within ±0.03 mm. Then, a grinding wheel and sandpaper are used to manually grind the burrs and flash on the surface, making the surface roughness reach Ra0.8 - Ra1.6 μm, improving the surface quality and ensuring the accuracy of the product.

[0041] The annealing treatment is carried out in a box-type resistance furnace. The mandrel sleeve is placed in the furnace and heated at a heating rate of 5 - 8 °C / min to 600 - 700 °C, and held at this temperature for 1 - 2 hours. After the holding ends, it is cooled in the furnace to below 300 °C, and then taken out for natural cooling. The annealing treatment can eliminate the internal stress generated during the cold heading process, improve the microstructure of the material, and enhance the strength and toughness of the mandrel sleeve.

[0042] The surface treatment adopts galvanizing and phosphating processes. The galvanizing process uses hot-dip galvanizing. The mandrel sleeve is immersed in a zinc bath at a temperature of 450 - 480 °C for 3 - 5 minutes, forming a uniform zinc layer on the surface of the mandrel sleeve with a thickness of 8 - 12 μm, improving the corrosion resistance of the mandrel sleeve. The phosphating treatment is to place the mandrel sleeve in a phosphating solution containing components such as zinc dihydrogen phosphate and react at a temperature of 30 - 50 °C for 15 - 20 minutes, forming a phosphating film on the surface and enhancing the wear resistance and adhesion of the mandrel sleeve.

[0043] By adopting the cold heading process, pressure is applied to the metal blank at room temperature to cause plastic deformation. Different from machining, machining achieves the required shape by removing materials and generates a large amount of waste; while the cold heading process utilizes the plastic flow of materials to gradually form the steel in the die, avoiding the situation where a large amount of materials are cut off and become waste. A bar with specific dimensions is selected as the starting material, and each subsequent cold heading process is based on the plastic deformation of this bar, without any excess material being cut off, improving the material utilization rate.

[0044] By placing the bar stock into the mold, changing its diameter and length, and forming a specific chamfered head 1, the plasticity of the material is reasonably utilized to prepare for subsequent processes. Through multiple subsequent flipping, upsetting, and hole pressing operations, and controlling the parameters of each process, including pressure, die shape, operation sequence, etc., the material can be fully utilized at each stage, gradually shaping the mandrel sleeve shape that meets the requirements. In the process of removing the residual material, cold upsetting is performed on the bar stock along the pressed holes, removing only a small amount of residual material that must be removed between the pressed holes, rather than removing a large amount of material as in cutting processing. This realizes the efficient utilization of the material, reduces the production cost, and is also more in line with the concepts of environmental protection and sustainable development.

[0045] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A cold heading process for a core bushing of an automotive suspension steering knuckle, characterized in that, It includes the following steps: S1. Select steel materials with high plasticity and low hardness for cutting to obtain the first bar; S2. Place the first bar into a mold for preliminary upsetting to obtain the second bar, and form a first chamfer head (1) at the bottom of the second bar; S3. Flip the second bar so that the first chamfer head (1) is set upward, upset the second bar to form a second chamfer head (2) on the side opposite to the first chamfer head (1) of the second bar, and form a first hole groove (3) on one side of the first chamfer head (1) of the second bar to obtain the third bar; S4. Flip the third bar so that the second chamfer head (2) is set upward, perform cold upsetting and punching on the first hole groove (3) of the third bar to form a first punched hole (4), and form a second hole groove (5) on one side of the second chamfer head (2) of the third bar to obtain the fourth bar; S5. Perform cold upsetting and punching on the second hole groove (5) of the fourth bar to form a second punched hole (6), and change the diameter of the first punched hole (4) to obtain the fifth bar; S6. Perform cold upsetting on the fifth bar along the first punched hole (4) and the second punched hole (6) to remove the residual material between the first punched hole (4) and the second punched hole (6) to obtain the sixth bar with an inner hole (7); S7. Perform cold upsetting forming on the sixth bar, and then perform trimming, annealing and surface treatment to obtain the core shaft sleeve.

2. The cold heading process of an automotive suspension steering knuckle spindle bushing according to claim 1, characterized in that: In S1, the elongation rate of the steel materials with high plasticity and low hardness is ≥25%, the Brinell hardness is ≤180HB, including carbon steel and stainless steel, and the diameter of the first bar is 22.6mm and the length is 47mm.

3. The cold heading process of an automotive suspension steering knuckle spindle bushing according to claim 1, characterized in that: In S2, the diameter of the second bar is 22.73mm and the length is 46.5mm, and the angle of the first chamfer head (1) is 150°.

4. The cold heading process of an automotive suspension steering knuckle spindle bushing according to claim 1, characterized in that: In S3, the diameter of the third bar is 22.83mm and the length is 47mm, the angle of the second chamfer head (2) is 160°, and the diameter of the first hole groove (3) is 12.79mm.

5. The cold heading process of an automotive suspension steering knuckle spindle bushing according to claim 1, characterized in that: In S4, the diameter of the first punched hole (4) is 12.75mm and the depth is 30mm, the diameter of the second hole groove (the diameter of the second hole groove (5) is 12.79mm, and the diameter of the fourth bar is 22.89mm and the length is 55.90mm.

6. The cold heading process of an automotive suspension steering knuckle spindle bushing according to claim 1, characterized in that: In S5, the diameter of the second punched hole (6) is 12.75mm and the depth is 30mm, and the diameter of the first punched hole (4) becomes 12.7mm.

7. A cold heading process for a vehicle suspension steering knuckle spindle bushing according to claim 1, characterized in that: In S5, the diameter of the fifth bar is 22.95mm and the length is 64mm, and in S6, the diameter of the inner hole (7) of the sixth bar is 12.7mm and the length is 64mm.

8. The cold heading process of an automotive suspension steering knuckle spindle bushing according to claim 1, characterized in that: In S7, the outer diameter of the core shaft sleeve is 23mm, the diameter of the inner hole (7) is 12.65mm, and the length is 64mm.

9. The cold heading process of an automotive suspension steering knuckle spindle bushing according to claim 1, characterized in that: In S7, the trimming includes removing the burrs and flash on the surface of the sixth bar, and precisely trimming the dimensions of the sixth bar, including the outer diameter and length, according to the designed dimensional tolerance range.

10. The cold heading process of an automotive suspension steering knuckle spindle bushing according to claim 1, characterized in that: In S7, the temperature of the annealing treatment is 600 - 700°C, the holding time is 1 - 2 hours, and the surface treatment includes galvanizing and phosphating treatment.

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