Anti-fracture cold forging forming method for steering pull rod of new energy vehicle

Abstract

The invention discloses an anti-fracture cold forging forming method for a steering pull rod of a new energy vehicle. The anti-fracture cold forging forming method comprises the following steps that (a) a 6110A aluminum alloy and a copper-zirconium alloy are preheated correspondingly; (b) smelting the preheated 6110A aluminum alloy and the preheated copper-zirconium alloy to obtain alloy liquid; (c) introducing protective gas into the alloy liquid, adding a refining agent to carry out refining treatment, and completing degassing and impurity removal; (d) carrying out hot top continuous casting on a product obtained in the step (c) to obtain an aluminum alloy cast ingot; (e) heating the aluminum alloy cast ingot to 420-450 DEG C, and preparing a bar by adopting a reverse extruder according to an extrusion ratio of (10-25): 1; (f) the bar is placed at the temperature of 545-555 DEG C to be subjected to solution treatment, the heat preservation time is 40-60 min, and then water quenching cooling is conducted; (g) heating the product in the step (f) to 170-180 DEG C from room temperature within 2-3 hours, then preserving heat for 7-9 hours, and naturally cooling to room temperature; and (h) carrying out cold forging forming on the product in the step (g). And the problem of hot forging coarse grain fracture is thoroughly solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal forming processing, and relates to a cold forging forming method of a vehicle steering rod, and in particular to a cold forging forming method for preventing a steering rod of a new energy vehicle from being fractured. Background Art

[0002] The steering tie rod is a critical component in a vehicle's steering mechanism, directly impacting handling stability, operating safety, and tire life. Steering tie rods are classified into two categories: straight and transverse. The straight tie rod transmits the motion of the steering rocker arm to the knuckle arm; the transverse tie rod forms the base of the steering trapezoidal mechanism and is a key component ensuring the correct kinematic relationship between the left and right steering wheels.

[0003] Traditional steering rods are produced using a hot forging process, which requires high-temperature heating of aluminum alloy billets (such as 6110A). This process leads to grain coarsening (average grain size ≥50μm), which can easily form microcracks within the product and increase the risk of fatigue fracture during service. Furthermore, hot forging consumes significant energy (heating temperature ≥400°C) and requires subsequent secondary processing, increasing overall costs. Traditional 6110A aluminum alloy has a tensile strength of ≤360MPa and a yield strength of ≤330MPa, making it difficult to meet the lightweight and high-strength requirements of new energy vehicles.

[0004] Chinese invention patent application number 202510313967.3 discloses a high-strength aluminum alloy conductor and its preparation method. The high-strength aluminum alloy conductor is composed, by mass percentage, of the following components: Si: 0.2%-0.4%, Mg: 0.5%-0.7%, Ti: 0.3%-0.5%, Zn: 0.3%-0.5%, Zr: 0.1%-0.15%, Sc: 0.05%-0.1%, Yb: 0.05%-0.15%, Sn: 0.01%-0.03%, Fe: ≤0.15%, B: 0.003%-0.005%, with the remainder being unavoidable impurities and Al. The method for producing this high-strength aluminum alloy conductor uses a multi-stage aging process to finely control the size of the precipitated phase. The multi-stage aging process involves holding the precipitates at different temperatures for different times, which helps the precipitates form precipitates of different sizes and morphologies at different stages. By finely controlling the size and distribution of these precipitates, the material's strength and conductivity can be further optimized. However, the multi-stage aging process is not only complex but also costly. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a cold forging method for preventing the fracture of the steering rod of new energy vehicles, so that the steering rod can meet the requirements of lightweight and high strength of new energy vehicles.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a cold forging method for preventing the fracture of a steering rod of a new energy vehicle, comprising the following steps:

[0007] (a) Preheating 6110A aluminum alloy and copper-zirconium alloy respectively;

[0008] (b) melting the preheated 6110A aluminum alloy and the copper-zirconium alloy to obtain a molten alloy at a melting temperature of 1400 to 1600° C.;

[0009] (c) introducing a protective gas into the alloy liquid and adding a refining agent to perform a refining treatment to complete degassing and impurity removal;

[0010] (d) hot-top continuous casting the product of step (c) to obtain an aluminum alloy ingot; the chemical composition of the aluminum alloy ingot is Si: 0.7-1.1%, Mg: 0.6-1.0%, Cu: 0.45-0.55%, Mn: 0.3-0.9%, Cr: 0.05-0.25%, Fe: ≤0.8%, Zn: ≤0.2%, Ti: ≤0.15%, Zr: 0.085-0.12%, and the balance is Al and unavoidable impurities;

[0011] (e) heating the aluminum alloy ingot to 420-450° C. and preparing a rod using a reverse extruder at an extrusion ratio of 10-25:1;

[0012] (f) subjecting the rod to solution treatment at 545-555° C. for 40-60 min, followed by water quenching;

[0013] (g) heating the product of step (f) from room temperature to 170-180° C. over 2-3 hours, then maintaining the temperature for 7-9 hours, and naturally cooling to room temperature;

[0014] (h) cold forging the product of step (g), wherein the single deformation of the cold forging is ≤25%.

[0015] Optimally, in step (a), the preheating temperature is 250-300° C. and the preheating time is 1-2 h.

[0016] Optimally, in step (c), the protective gas is nitrogen or argon, and its inlet flow rate is 0.5 to 2 L / min.

[0017] Furthermore, in step (c), the amount of the refining agent added is 0.1 to 0.3% of the mass of the alloy liquid, and the refining agent is a mixture of one or more selected from RJ01, XF-JL-1XF-JL-2, ADC12 and A356.

[0018] Optimally, in step (d), the casting speed of the hot top continuous casting is 40-50 mm / min, and the diameter of the aluminum alloy ingot is 120-180 mm.

[0019] Optimally, in step (e), the surface roughness of the rod is ≤ Ra 1.6 μm, and the internal grain size is ≤ 15 μm.

[0020] Optimally, in step (f), the cooling rate of the water quenching is ≥100°C / s.

[0021] Optimally, in step (h), the cold forging die is preheated at a temperature of 150°C to 180°C.

[0022] Due to the application of the above technical solutions, the present invention has the following advantages over the existing technology: the cold forging method for preventing fracture of steering rods for new energy vehicles increases the content of Cu and Zr, which can enhance the solid solution strengthening effect and facilitate the formation of Al3Zr dispersed phase to inhibit grain growth. On the other hand, the combination of aluminum alloy composition optimization, reverse extrusion molding and solution treatment-long-term artificial aging enables the material to be cold forged at room temperature. The resulting product has grain refinement to ≤10μm, surface hardness ≥120HB, tensile strength ≥400MPa, and yield strength ≥380MPa, completely solving the problem of coarse-grained fracture during hot forging, and the fatigue life of the product is increased by more than 3 times. By using cold forging instead of hot forging, energy consumption is reduced by 60% (no high-temperature heating is required) and processing costs are reduced by 30%. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a low-magnification structural inspection image of the steering rod of a new energy vehicle in Example 3;

[0024] Figure 2 This is a low-magnification structural inspection picture of the steering rod of the new energy vehicle in Comparative Example 3. DETAILED DESCRIPTION

[0025] The present invention provides a cold forging method for preventing the fracture of a steering tie rod of a new energy vehicle, comprising the following steps: (a) preheating a 6110A aluminum alloy and a copper-zirconium alloy respectively; (b) smelting the preheated 6110A aluminum alloy and the copper-zirconium alloy in proportion to obtain an alloy liquid, wherein the smelting temperature is 1400-1600° C.; (c) introducing a protective gas into the alloy liquid and adding a refining agent to perform a refining treatment (the refining treatment time is 20-40 minutes) to complete degassing and impurity removal; and (d) hot top continuous casting the product of step (c) to obtain an aluminum alloy ingot; the chemical composition of the aluminum alloy ingot is Si: 0.7-1.1%, Mg: 0.6-1.0%, Cu: 0.45-0.55%, Mn: 0.3-0. 9%, Cr: 0.05-0.25%, Fe: ≤0.8%, Zn: ≤0.2%, Ti: ≤0.15%, Zr: 0.085-0.12%, and the balance being Al and unavoidable impurities; (e) heating the aluminum alloy ingot to 420-450° C. and preparing a rod with an extrusion ratio of 10-25:1 using a reverse extruder; (f) subjecting the rod to a solution treatment at 545-555° C. for 40-60 min, followed by water quenching; (g) heating the product of step (f) from room temperature to 170-180° C. within 2-3 h, followed by holding for 7-9 h, and naturally cooling to room temperature; (h) cold forging the product of step (g), wherein the single deformation amount of the cold forging is ≤25%. On the one hand, the Cu and Zr contents were increased, which enhanced the solid solution strengthening effect and facilitated the formation of Al3Zr dispersed phases to inhibit grain growth. On the other hand, combined with the optimization of aluminum alloy composition, reverse extrusion molding, and solution treatment-long-term artificial aging, the material is capable of cold forging at room temperature. The resulting product has grain refinement to ≤10μm, surface hardness ≥120HB, tensile strength ≥400MPa, and yield strength ≥380MPa, completely solving the problem of coarse-grained fracture during hot forging and increasing the product fatigue life by more than three times. By replacing hot forging with cold forging, energy consumption is reduced by 60% (no high-temperature heating is required) and processing costs are reduced by 30%.

[0026] In step (a), the preheating temperature is 250-300°C and the time is 1-2h. In step (c), the protective gas is nitrogen or argon, and the flow rate thereof is 0.5-2L / min. In step (c), the amount of the refining agent added is 0.1-0.3% of the mass of the alloy liquid, and the refining agent is a mixture of one or more selected from RJ01, XF-JL-1XF-JL-2, ADC12 and A356. In step (d), the casting speed of the hot top continuous casting is 40-50mm / min, and the diameter of the aluminum alloy ingot is 120-180mm. In step (e), the surface roughness of the rod is ≤Ra1.6μm, and the internal grain size is ≤15μm. In step (f), the cooling rate of the water quenching is ≥100°C / s. In step (h), the cold forging die is preheated at a temperature of 150°C to 180°C.

[0027] The preferred embodiments of the present invention will be described in detail below.

[0028] Example 1

[0029] The cold forging method for preventing the fracture of a steering rod of a new energy vehicle of the present invention comprises the following steps:

[0030] (a) 6110A aluminum alloy and copper-zirconium alloy were preheated at 250°C for 2 h.

[0031] (b) melting the preheated 6110A aluminum alloy and copper-zirconium alloy at 1400° C. to obtain a molten alloy;

[0032] (c) Argon gas was introduced into the alloy solution at a flow rate of 0.5 L / min, and a refining agent (RJ01, 0.1% of the mass of the alloy solution) was added for refining (40 min) to complete degassing and impurity removal.

[0033] (d) hot top continuous casting (40 mm / min) of the product of step (c) to obtain an aluminum alloy ingot (180 mm in diameter); analysis revealed that the chemical composition of the aluminum alloy ingot was Si: 0.7%, Mg: 1.0%, Cu: 0.45%, Mn: 0.3%, Cr: 0.05%, Fe: 0.5%, Zn: 0.15%, Ti: 0.10%, Zr: 0.12%, with the remainder being Al and unavoidable impurities;

[0034] (e) The aluminum alloy ingot was heated to 420°C and a rod was prepared using a reverse extruder at an extrusion ratio of 10:1 (the surface roughness of the rod was ≤ Ra 1.6 μm and the internal grain size was ≤ 15 μm);

[0035] (f) The bars were solution treated at 545 °C for 60 min and then water quenched (cooling rate of approximately 100 °C / s).

[0036] (g) heating the product of step (f) from room temperature to 170° C. (the heating process lasts for 2 hours), then maintaining the temperature for 7 hours, and naturally cooling to room temperature;

[0037] (h) cold forging the product of step (g) using a die (the die is preheated to 150° C.), wherein the single deformation amount of the cold forging is 25%.

[0038] Example 2

[0039] The cold forging method for preventing the fracture of a steering rod of a new energy vehicle of the present invention comprises the following steps:

[0040] (a) 6110A aluminum alloy and copper-zirconium alloy were preheated at 300°C for 1 h.

[0041] (b) melting the preheated 6110A aluminum alloy and copper-zirconium alloy at 1600° C. to obtain a molten alloy;

[0042] (c) Argon gas was introduced into the alloy solution at a flow rate of 2 L / min, and a refining agent (RJ01, 0.3% of the mass of the alloy solution) was added for refining (20 min) to complete degassing and impurity removal.

[0043] (d) hot-top continuous casting (50 mm / min) of the product of step (c) to obtain an aluminum alloy ingot (120 mm in diameter); analysis revealed that the chemical composition of the aluminum alloy ingot was Si: 1.1%, Mg: 0.6%, Cu: 0.55%, Mn: 0.9%, Cr: 0.25%, Fe: 0.4%, Zn: 0.12%, Ti: 0.12%, Zr: 0.085%, with the remainder being Al and unavoidable impurities;

[0044] (e) The aluminum alloy ingot was heated to 450°C and a rod was prepared using a reverse extruder with an extrusion ratio of 25:1;

[0045] (f) The bar was solution treated at 555 °C for 40 min and then water quenched (cooling rate of approximately 100 °C / s);

[0046] (g) heating the product of step (f) from room temperature to 180° C. (the heating process lasts for 3 hours), then keeping the temperature for 9 hours, and naturally cooling to room temperature;

[0047] (h) cold forging the product of step (g) using a die (the die is preheated to 180° C.), wherein the single deformation of the cold forging is 15%.

[0048] Example 3

[0049] The cold forging method for preventing the fracture of a steering rod of a new energy vehicle of the present invention comprises the following steps:

[0050] (a) 6110A aluminum alloy and copper-zirconium alloy were preheated at 280°C for 1.5 h.

[0051] (b) melting the preheated 6110A aluminum alloy and copper-zirconium alloy at 1500° C. to obtain a molten alloy;

[0052] (c) Argon gas was introduced into the alloy solution at a flow rate of 1 L / min, and a refining agent (RJ01, 0.2% of the mass of the alloy solution) was added for refining (30 min) to complete degassing and impurity removal.

[0053] (d) hot top continuous casting (45 mm / min) of the product of step (c) to obtain an aluminum alloy ingot (150 mm in diameter); analysis revealed that the chemical composition of the aluminum alloy ingot was Si: 0.9%, Mg: 0.8%, Cu: 0.50%, Mn: 0.5%, Cr: 0.15%, Fe: 0.6%, Zn: 0.10%, Ti: 0.10%, and Zr: 0.10%, with the remainder being Al and unavoidable impurities;

[0054] (e) The aluminum alloy ingot was heated to 450°C and a rod was prepared using a reverse extruder with an extrusion ratio of 25:1;

[0055] (f) The bar was solution treated at 550 °C for 50 min and then water quenched (cooling rate of approximately 100 °C / s);

[0056] (g) heating the product of step (f) from room temperature to 175° C. (the heating process lasts for 3 hours), then maintaining the temperature for 8 hours, and naturally cooling to room temperature;

[0057] (h) The product of step (g) is cold forged using a mold (the mold is preheated to 180° C.). The single deformation of the cold forging is 20%. The macroscopic microstructure inspection diagram is as follows: Figure 1 As shown, there is no coarse grain ring.

[0058] Comparative Example 1

[0059] This example provides a cold forging method for preventing a tie rod from breaking, which is basically the same as that in Example 3, except that step (f) is not performed, and the rod in step (e) is directly heated from room temperature to 175°C.

[0060] Comparative Example 2

[0061] This example provides a cold forging method for preventing a pull rod from breaking, which is basically the same as that in Example 3, with the only difference being that in step (g), the product of step (f) is heated from room temperature to 175°C (the heating process lasts for 1 hour), then kept warm for 2 hours, and then naturally cooled to room temperature.

[0062] Comparative Example 3

[0063] This example provides a cold forging method for preventing a tie rod from breaking, which is basically the same as that in Example 3, except that no copper-zirconium alloy is added in step (a). The chemical composition of the aluminum alloy ingot is Si: 0.9%, Mg: 0.8%, Cu: 0.20%, Mn: 0.5%, Cr: 0.15%, Fe: 0.6%, Zn: 0.10%, Ti: 0.10%, Zr: 0.05%, and the remainder is Al and unavoidable impurities. The macrostructure inspection diagram is shown in FIG. Figure 2 As shown, a coarse crystal ring of 2 to 3 mm can be seen.

[0064] Comparative Example 4

[0065] This example provides a cold forging method for preventing a pull rod from breaking, which is basically the same as that in Example 3, with the only difference being that no copper-zirconium alloy is added in step (a). Thus, the chemical composition of the aluminum alloy ingot is Si: 0.9%, Mg: 0.8%, Cu: 0.60%, Mn: 0.5%, Cr: 0.15%, Fe: 0.6%, Zn: 0.10%, Ti: 0.10%, Zr: 0.15%, and the remainder is Al and unavoidable impurities.

[0066] Comparative Example 5

[0067] This example provides a cold forging method for preventing a tie rod from breaking, which is basically the same as that in Example 3, with the only difference being that in step (f), the rod is placed at 500°C for solution treatment.

[0068] Comparative Example 6

[0069] This example provides a cold forging method for preventing a tie rod from breaking, which is basically the same as that in Example 3, with the only difference being that in step (f), the rod is subjected to solution treatment at 580°C.

[0070] The performance tests were carried out on the products of Examples 1-3 and Comparative Examples 1-6, and the results are listed in Table 1.

[0071]

[0072] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A cold forging method for preventing the fracture of a steering rod of a new energy vehicle, characterized in that: The following steps are involved: (a) Preheating 6110A aluminum alloy and copper-zirconium alloy respectively; (b) melting the preheated 6110A aluminum alloy and the copper-zirconium alloy to obtain a molten alloy at a melting temperature of 1400 to 1600° C.; (c) introducing a protective gas into the alloy liquid and adding a refining agent to perform a refining treatment to complete degassing and impurity removal; (d) hot-top continuous casting the product of step (c) to obtain an aluminum alloy ingot; the chemical composition of the aluminum alloy ingot is Si: 0.7-1.1%, Mg: 0.6-1.0%, Cu: 0.45-0.55%, Mn: 0.3-0.9%, Cr: 0.05-0.25%, Fe: ≤0.8%, Zn: ≤0.2%, Ti: ≤0.15%, Zr: 0.085-0.12%, and the balance is Al and unavoidable impurities; (e) heating the aluminum alloy ingot to 420-450° C. and preparing a rod using a reverse extruder at an extrusion ratio of 10-25:1; (f) subjecting the rod to solution treatment at 545-555° C. for 40-60 min, followed by water quenching; (g) heating the product of step (f) from room temperature to 170-180° C. over 2-3 hours, then maintaining the temperature for 7-9 hours, and naturally cooling to room temperature; (h) cold forging the product of step (g), wherein the single deformation of the cold forging is ≤25%.

2. The cold forging method for preventing the steering rod of a new energy vehicle from being fractured according to claim 1, characterized in that: In step (a), the preheating temperature is 250-300° C. and the preheating time is 1-2 hours.

3. The cold forging method for preventing the fracture of the steering rod of a new energy vehicle according to claim 1 is characterized in that: In step (c), the protective gas is nitrogen or argon, and the flow rate thereof is 0.5 to 2 L / min.

4. The cold forging method for preventing the fracture of a steering rod of a new energy vehicle according to claim 1 or 3, characterized in that: In step (c), the amount of the refining agent added is 0.1-0.3% of the mass of the alloy liquid, and the refining agent is a mixture of one or more selected from RJ01, XF-JL-1XF-JL-2, ADC12 and A356.

5. The cold forging method for preventing the fracture of the steering rod of a new energy vehicle according to claim 1 is characterized in that: In step (d), the casting speed of the hot top continuous casting is 40-50 mm / min, and the diameter of the aluminum alloy ingot is 120-180 mm.

6. The cold forging method for preventing the steering rod of a new energy vehicle from being fractured according to claim 1, characterized in that: In step (e), the surface roughness of the rod is ≤ Ra 1.6 μm, and the internal grain size is ≤ 15 μm.

7. The cold forging method for preventing the fracture of a steering rod of a new energy vehicle according to claim 1, characterized in that: In step (f), the cooling rate of the water quenching is ≥100°C / s.

8. The cold forging method for preventing the fracture of a steering rod of a new energy vehicle according to claim 1, characterized in that: In step (h), the cold forging die is preheated at a temperature of 150°C to 180°C.

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