Integrated casting method for steering yoke

Abstract

The invention discloses an integrated casting method for a steering yoke, and belongs to the technical field of nodular cast iron casting, and the integrated casting method comprises the following steps: S1, preparing a mold sand mold for casting a steering yoke casting; s2, molten metal used for casting the steering yoke is prepared, and the molten metal is poured into the riser cavity and enters the casting cavity through the riser neck and the reinforcing rib cavity for casting forming; s3, cooling the mold sand mold after casting forming is completed, and taking out the casting in the mold sand mold; s4, the parts, corresponding to a riser cavity, a riser neck and a reinforcing rib cavity, of the taken-out casting are cut and removed, and then shot blasting and grinding are conducted; integrated forming is achieved in a casting mode, the material utilization rate is increased, the reinforcing rib cavity is additionally arranged, meanwhile, the die number of the riser cavity and the die number of the riser neck are limited, and therefore effective feeding can be achieved during pouring, and the final casting quality is ensured.

Description

Technical Field

[0001] This invention relates to the field of spherical cast iron casting technology, and specifically to an integrated casting method for steering knuckle forks. Background Technology

[0002] As the automotive industry moves towards automation, intelligence, and lightweighting, automotive steering systems are facing higher technical requirements and performance challenges. Against this backdrop, the manufacturing process of the steering knuckle fork and sleeve assembly in traditional steering systems urgently needs innovation. Current mainstream processes employ separate manufacturing: the fork portion is typically forged, resulting in bulky products and limitations in achieving complex structural designs; the sleeve portion uses seamless steel tubing. The two are ultimately assembled using welding.

[0003] Compared to the traditional "forging + welding" approach, integrated casting technology offers significant advantages. This process allows the steering knuckle fork's slot, spline bottom hole, and lightweight internal cavities to be formed in a single casting operation. This technological approach directly improves efficiency; through optimization, the weight of a single blank can be reduced to as low as 0.5 kg, and material utilization can be increased to over 85%.

[0004] However, due to the large differences in wall thickness between castings of different specifications, the riser cannot effectively compensate for the wall thickness of the steering knuckle fork, which affects the quality of the final casting. Therefore, it is urgent to design an integrated casting method for steering knuckle forks to solve the above problems. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to improve the material utilization rate by adopting the casting method for integrated molding, and to achieve effective feeding during pouring by adding reinforcing rib cavities and limiting the riser cavity modulus and riser neck modulus, thereby ensuring the quality of the final casting.

[0006] An integrated casting method for a steering knuckle fork includes the following steps:

[0007] S1: Prepare a sand mold for casting the steering knuckle fork. The sand mold includes a riser cavity, a riser neck, a reinforcing rib cavity, and a casting cavity connected sequentially from top to bottom. The casting cavity includes a fork cavity corresponding to the steering knuckle fork portion, a sleeve cavity corresponding to the sleeve portion, and a key cavity corresponding to the key portion. The reinforcing rib cavity is located on the side of the sleeve cavity away from the key cavity along the axial direction of the sleeve cavity, and extends from the junction of the fork cavity and the sleeve cavity to the junction of the sleeve cavity and the key cavity.

[0008] S2: Prepare molten metal for casting the steering knuckle fork, pour the molten metal into the riser cavity, pass through the riser neck and reinforcing rib cavity, and enter the casting cavity to form the casting.

[0009] S3: Cool the mold sand mold after the casting is formed, and then remove the casting from the mold sand mold;

[0010] S4: Cut off the portions of the casting that correspond to the riser cavity, riser neck, and reinforcing rib cavity after removal. Then, shot blast and grind the casting after cutting to form the final steering knuckle fork.

[0011] In a preferred embodiment of the present invention, the cross-section of the reinforcing rib cavity along the extending direction is rectangular, the minimum width of the rectangle is greater than or equal to 7 mm, and the riser cavity module is [missing value]. ,and ,in The standard coefficient for the modulus of ductile iron is... It is 0.8-1.0. The stiffener cavity module is the stiffener cavity module. ,in The volume of the casting corresponds to the cavity of the casting. The surface area of ​​the casting corresponding to the casting cavity is [value], and the riser neck module is [value]. ,and .

[0012] As a preferred embodiment of the present invention, the molten metal comprises Fe, C, Si, Mn, S, and P, wherein the mass percentage of C in the molten metal is 3.7%-3.9%, the mass percentage of Si is 1.8%-2.4%, the mass percentage of Mn is less than or equal to 0.3%, the mass percentage of S is less than or equal to 0.015%, the mass percentage of P is less than or equal to 0.05%, and the remaining mass percentage element in the molten metal is Fe.

[0013] As a preferred embodiment of the present invention, step S2, in which the molten metal is poured into the riser cavity, passes through the riser neck and the reinforcing rib cavity, and enters the casting cavity for casting, specifically includes:

[0014] The molten metal is poured into a spheroidizing treatment bag for spheroidizing treatment. The amount of molten metal treated in each spheroidizing treatment bag is 800kg-1200kg, and the amount of spheroidizing agent added in each bag is 8kg-15kg. Then, the molten metal after spheroidizing treatment is transferred from the spheroidizing treatment bag to a casting ladle. When the temperature of the molten metal is 1330℃-1400℃, the molten metal in the casting ladle is poured into the riser cavity, passes through the riser neck and the reinforcing rib cavity, and enters the casting cavity to form the casting.

[0015] As a preferred embodiment of the present invention, the melting temperature of the molten metal is 1480℃-1540℃.

[0016] As a preferred embodiment of the present invention, the cooling of the mold sand mold after the casting is completed in step S3 specifically includes:

[0017] The mold sand mold for forming the casting is cooled for a time of 1 hour or more.

[0018] As a preferred embodiment of the present invention, step S3, which involves removing the casting from the mold sand, specifically includes:

[0019] Remove the casting from the mold sand mold at a temperature of less than or equal to 200°C.

[0020] As a preferred technical solution of the present invention, the mold sand mold is manufactured by molding, the sand injection pressure of the molding machine is 0.2 Bar-0.4 Bar, the extrusion pressure is 8 Bar-12 Bar, and the target compaction rate is 23%-30%.

[0021] As a preferred embodiment of the present invention, the shot blasting is performed using a shot blasting machine, the shot blasting time of the shot blasting machine is 8-10 minutes, and the diameter of the steel shot of the shot blasting machine is 1.2 mm-1.8 mm.

[0022] As a preferred embodiment of the present invention, the grinding is performed on the casting to remove burrs and flash.

[0023] The beneficial effects of this invention are reflected in:

[0024] 1. By adopting a one-time integral casting method to replace the traditional two-step manufacturing process of forging and welding, the welding process is fundamentally eliminated, improving product quality and production efficiency. Reinforcing rib cavities are set in the mold sand mold, and their positions are defined to allow the molten metal in the riser cavity to flow smoothly through the reinforcing rib cavities for feeding. The dimensions of the reinforcing rib cavities are limited, with the minimum width of the rectangle being greater than or equal to 7mm, to ensure that the feeding channel has sufficient cross-sectional area and modulus, allowing the reinforcing rib cavities to fit within the casting cavity. Before the molten metal solidifies, it is not blocked, ensuring that the molten metal in the reinforcing rib cavity solidifies later than or simultaneously with the area requiring feeding. By limiting the modulus of the riser cavity, it is ensured that the molten metal in the riser cavity solidifies later than the feeding area of ​​the casting. This allows the molten metal in the riser cavity to remain liquid and effectively feed during the solidification and shrinkage of the molten metal in the casting cavity, thus ensuring the overall feeding effect of casting. This results in a solidification gradient in the casting from away from the gate to the gate, and from thin wall to thick wall, ensuring the final casting performance.

[0025] 2. By limiting the riser neck module, effective feeding is ensured while facilitating subsequent cutting operations. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a casting blank according to the present invention.

[0027] In the diagram: 1. Fork section; 2. Sleeve section; 3. Keyway section; 4. Reinforcing rib; 5. Riser neck; 6. Riser. Detailed Implementation

[0028] The invention will now be described in further detail with reference to the accompanying drawings.

[0029] An integrated casting method for a steering knuckle fork includes the following steps:

[0030] S1: Prepare a sand mold for casting the steering knuckle fork. The sand mold includes a riser cavity, a riser neck, a reinforcing rib cavity, and a casting cavity that are connected sequentially from top to bottom. The casting cavity includes a fork cavity corresponding to the steering knuckle fork part 1, a sleeve cavity corresponding to the sleeve part 2, and a groove and key cavity corresponding to the key part 3. The reinforcing rib cavity is located on the side of the sleeve cavity away from the groove and key cavity along the axial direction of the sleeve cavity, and extends from the junction of the fork cavity and the sleeve cavity to the junction of the sleeve cavity and the key cavity.

[0031] Specifically:

[0032] The cross-section of the reinforcing rib cavity along its extension direction is rectangular, with a minimum width of 7 mm or more in the rectangle, and the riser cavity module is [missing value]. ,and ,in This is the standard coefficient for the modulus of ductile iron. The stiffener cavity module is the stiffener cavity module. ,in The volume of the casting corresponds to the cavity of the casting. The surface area of ​​the casting corresponding to the casting cavity is [value], and the riser neck module is [value]. ,and ;

[0033] The standard coefficient of the modulus of milled cast iron The preferred value is 0.8-1.0, and the standard coefficient for the modulus of the ductile iron is... If it is 1.0, then ;

[0034] By setting reinforcing rib cavities on the mold sand mold and limiting the position of the reinforcing rib cavities, the molten metal in the riser cavity can flow smoothly through the reinforcing rib cavities for feeding. By limiting the size of the reinforcing rib cavities, that is, the minimum width of the rectangle is greater than or equal to 7mm, it is ensured that the feeding channel has sufficient cross-sectional area and modulus, so that the reinforcing rib cavities are not blocked before the molten metal in the casting cavity solidifies, and the molten metal in the reinforcing rib cavities solidifies later than or simultaneously with the area that needs feeding.

[0035] By limiting the riser cavity modulus, it is ensured that the molten metal in the riser cavity solidifies later than the feeding part of the casting, so that the molten metal in the riser cavity can remain liquid and effectively feed the casting when the molten metal in the casting cavity solidifies and shrinks.

[0036] By limiting the riser neck module, effective feeding is ensured while facilitating subsequent cutting operations;

[0037] The mold sand mold is manufactured using molding. The sand injection pressure of the molding machine is 0.2 Bar-0.4 Bar, the extrusion pressure is 8 Bar-12 Bar, and the target compaction rate is 23%-30%. Furthermore, a DISA molding machine is selected for the molding sand mold to form a precise cavity, providing a good foundation for the pouring of molten metal. This is beneficial for obtaining castings with accurate shapes and qualified dimensions, improving the quality and performance of the integrated steering knuckle fork casting. Preferably, a compact mold sand mold is selected to achieve 12 pieces per mold, thereby improving overall efficiency. When injecting sand into the cavity formed by the DISA molding machine and the mold sand mold, reasonable control of the sand injection pressure, extrusion pressure, and target compaction rate can ensure that the molding sand is fully filled and compacted in the cavity, improving the density and surface quality of the cavity, thereby ensuring the dimensional accuracy and surface finish of the casting.

[0038] S2: Prepare molten metal for casting the steering knuckle fork, pour the molten metal into the riser cavity, pass through the riser neck and reinforcing rib cavity, and enter the casting cavity to form the casting.

[0039] Specifically:

[0040] The molten metal comprises Fe, C, Si, Mn, S, and P, wherein the mass percentage of C in the molten metal is 3.7%-3.9%, the mass percentage of Si is 1.8%-2.4%, the mass percentage of Mn is less than or equal to 0.3%, the mass percentage of S is less than or equal to 0.015%, and the mass percentage of P is less than or equal to 0.05%. The remaining mass percentage of the molten metal is Fe. The melting temperature of the molten metal is 1480℃-1540℃. By strictly controlling the mass ratio of each component in the molten metal, it is possible to ensure that the material used has good mechanical properties, such as strength and toughness, to meet the requirements of the integrated steering knuckle fork casting under complex working conditions. At the same time, controlling the melting temperature between 1480℃ and 1540℃ can fully melt and homogenize the molten metal, reduce the generation of defects such as slag porosity and gas porosity, improve the quality of molten iron, and provide a guarantee for the subsequent pouring and casting quality.

[0041] The molten metal is poured into a spheroidizing treatment bag for spheroidizing treatment. Each spheroidizing treatment bag contains 800-1200 kg of molten metal, and each bag contains 8-15 kg of spheroidizing agent. The spheroidized metal is then transferred from the spheroidizing treatment bag to a casting ladle. At a temperature of 1330℃-1400℃, the molten metal from the casting ladle is poured into the riser cavity, passing through the riser neck and reinforcing rib cavity before entering the casting mold cavity for casting. Forming, by controlling the pouring temperature of the molten metal between 1330℃ and 1400℃, can ensure that the molten metal has good fluidity and filling properties during the pouring process, fully filling all corners of the cavity, reducing defects such as cold shuts and incomplete pouring, and improving the density and surface quality of the casting. The amount of spheroidizing agent added is 8 to 15 kg, which is conducive to the uniform distribution of the spheroidizing agent in the molten metal during the spheroidizing treatment process, promoting graphite spheroidization, improving the spheroidization level of the casting, and further improving the mechanical properties and good metallographic structure of the casting.

[0042] S3: Cool the mold sand mold after the casting is formed, wherein the cooling time is greater than or equal to 1 hour, and then remove the casting from the mold sand mold, wherein the casting is removed from the mold sand mold at a temperature less than or equal to 200°C.

[0043] During cooling, controlling the cooling time and the temperature at which the casting is removed can prevent defects such as cracks and deformation from occurring due to excessively rapid cooling or excessively high temperatures, thus ensuring the internal structure and mechanical properties of the casting. Shot blasting, on the other hand, removes oxide scale, sand particles, and other impurities, as well as burrs and flash, from the surface of the casting, improving surface finish and aesthetics.

[0044] S4: The portions of the casting corresponding to the riser cavity, riser neck, and reinforcing rib cavity are cut and removed after extraction. Subsequently, the casting after cutting and removal is shot-blasted and polished to form the final steering knuckle fork. The shot blasting is performed using a shot blasting machine with a shot blasting time of 8-10 minutes, preferably 9 minutes. The diameter of the steel shot used in the shot blasting machine is 1.2mm-1.8mm, preferably 1.5mm. The polishing is performed on the casting to remove burrs and flash. Through shot blasting and polishing, oxide scale, sand particles, and other impurities and burrs on the surface of the casting are removed, improving the surface finish and aesthetics. At the same time, the surface of the casting is strengthened, improving its fatigue strength and corrosion resistance.

[0045] After the casting of the steering knuckle fork is completed, the cast parts are subjected to quality inspection.

[0046] Specifically:

[0047] Strict quality inspections are conducted on the shot-blasted steering knuckle fork castings, including visual inspection, dimensional measurement, and internal defect detection.

[0048] Preferably, the visual inspection mainly checks whether there are defects such as cracks, sand holes, and air holes on the surface of the casting;

[0049] High-precision measuring instruments are used for dimensional measurement to ensure that the dimensions of each part of the casting meet the design requirements;

[0050] Internal defect detection can be performed using methods such as X-ray flaw detection, magnetic particle flaw detection, and dissection to check whether there are defects such as porosity and shrinkage cavities inside the casting.

[0051] Products that fail inspection are promptly processed or reworked to ensure product quality. Castings are cut and sampled for hardness testing and strength testing.

[0052] Under the casting conditions and parameters shown in Table 1, castings with the mechanical properties shown in Table 2 can be obtained after testing.

[0053] serial number C(3.7%-3.9%) Si (1.8%-2.4%) Mn (≤0.3%) S(0.015%) P(≤0.05%) Dissolution temperature (1480℃~1540℃) Serving weight (800~1200Kg) Pouring temperature (1330~1400℃) Spheroidizing agent addition amount (8~15Kg) 1 3.784 2.11 0.24 0.008 0.025 1523℃ 1032Kg 1340℃ 10Kg 2 3.80 2.10 0.23 0.010 0.024 1531℃ 1005Kg 1366℃ 10Kg 3 3.79 2.13 0.24 0.011 0.024 1528℃ 1018Kg 1386℃ 10Kg 4 3.78 2.11 0.25 0.010 0.026 1530℃ 1016Kg 1371℃ 10Kg 5 3.80 2.11 0.25 0.010 0.022 1536℃ 1006Kg 1368℃ 10Kg

[0054] Table 1 shows the casting conditions and parameters.

[0055] serial number Spheroidization rate (≥80%) Tensile strength (≥500 MPa) Yield strength (320 MPa) Elongation (≥7%) Hardness 150-250 HB 1 90 562 359 15.2 192 2 90 553 367 15.8 200 3 90 572 369 14.8 200 4 90 562 357 14.6 201 5 90 569 362 15.2 199

[0056] Table 2 shows the mechanical properties of the castings.

[0057] According to the mechanical properties shown in Table 2, the castings produced by the casting method of the present invention meet the requirements of spheroidization rate ≥80%, tensile strength ≥500Mpa, elongation ≥7%, yield strength ≥320Mpa, and hardness: HB150-250.

[0058] Combined with appendix Figure 1 As shown, attached Figure 1 This is a schematic diagram of a casting blank prepared using the modified preparation method. It shows the structural relationship between the casting cavity, reinforcing rib cavity, riser neck, and riser neck cavity corresponding to the casting parts. The reinforcing rib 4 is located above the casting body, and the riser 6 is connected to the casting body through the riser neck 4 and the reinforcing rib 3. Specifically, the casting body includes a fork portion 1, a sleeve portion 2, and a key portion 3. The fork portion 1 is located at one end of the sleeve portion 2, and the key portion 3 is located at the other end of the sleeve portion 2. The reinforcing rib 4 is located above the sleeve portion 2. The casting cavity corresponds to the casting body; specifically, the fork portion cavity corresponds to the fork portion 1, the sleeve portion cavity corresponds to the sleeve portion 2, and the key portion cavity corresponds to the key portion 3. Preferably, the length, width, and height of the steering fork are 159.5 × 42 × 36 mm, with the sleeve portion 2 having a wall thickness of 4.5 mm. Depending on specific casting requirements, a steering fork with a width and height range of 5 mm can be fitted.

[0059] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. An integrated casting method for a steering knuckle fork, characterized in that, Includes the following steps: S1: Prepare a mold sand pattern for casting the steering knuckle fork. The mold sand pattern includes a riser cavity, a riser neck, a reinforcing rib cavity and a casting cavity connected from top to bottom. The casting cavity includes a fork cavity corresponding to the steering knuckle fork part (1), a sleeve cavity corresponding to the sleeve part (2) and a groove key cavity corresponding to the groove key part (3). The reinforcing rib cavity is located on the side of the sleeve cavity away from the groove key cavity along the axial direction of the sleeve cavity, and extends from the junction of the fork cavity and the sleeve cavity to the junction of the sleeve cavity and the groove key cavity. S2: Prepare molten metal for casting the steering knuckle fork, pour the molten metal into the riser cavity, pass through the riser neck and reinforcing rib cavity, and enter the casting cavity to form the casting. S3: Cool the mold sand mold after the casting is formed, and then remove the casting from the mold sand mold; S4: Cut off the portions of the casting that correspond to the riser cavity, riser neck, and reinforcing rib cavity after removal. Then, shot blast and grind the casting after cutting to form the final steering knuckle fork.

2. The integrated casting method for a steering knuckle fork according to claim 1, characterized in that: The cross-section of the reinforcing rib cavity along its extension direction is rectangular, with a minimum width of 7 mm or more in the rectangle, and the riser cavity module is [missing value]. ,and ,in The standard coefficient for the modulus of ductile iron is... It is 0.8-1.

0. The stiffener cavity module is the stiffener cavity module. ,in The volume of the casting corresponds to the cavity of the casting. The surface area of ​​the casting corresponding to the casting cavity is [value], and the riser neck module is [value]. ,and .

3. The integrated casting method for a steering knuckle fork according to claim 1, characterized in that: The molten metal contains Fe, C, Si, Mn, S, and P, wherein the mass percentage of C in the molten metal is 3.7%-3.9%, the mass percentage of Si is 1.8%-2.4%, the mass percentage of Mn is less than or equal to 0.3%, the mass percentage of S is less than or equal to 0.015%, the mass percentage of P is less than or equal to 0.05%, and the remaining mass percentage of the molten metal is Fe.

4. The integrated casting method for a steering knuckle fork according to claim 3, characterized in that: In step S2, the molten metal is poured into the riser cavity, passes through the riser neck and reinforcing rib cavity, and enters the casting cavity to form the casting. Specifically, this includes: The molten metal is poured into a spheroidizing treatment bag for spheroidizing treatment. The amount of molten metal treated in each spheroidizing treatment bag is 800kg-1200kg, and the amount of spheroidizing agent added in each bag is 8kg-15kg. Then, the molten metal after spheroidizing treatment is transferred from the spheroidizing treatment bag to a casting ladle. When the temperature of the molten metal is 1330℃-1400℃, the molten metal in the casting ladle is poured into the riser cavity, passes through the riser neck and the reinforcing rib cavity, and enters the casting cavity to form the casting.

5. The integrated casting method for a steering knuckle fork according to claim 4, characterized in that: The melting temperature of the molten metal is 1480℃-1540℃.

6. The integrated casting method for a steering knuckle fork according to claim 1, characterized in that: The cooling of the mold sand form after the casting is completed in step S3 specifically includes: The mold sand mold for forming the casting is cooled for a time of 1 hour or more.

7. The integrated casting method for a steering knuckle fork according to claim 6, characterized in that: The step of removing the casting from the mold sand mold in S3 specifically includes: Remove the casting from the mold sand mold at a temperature of less than or equal to 200°C.

8. The integrated casting method for a steering knuckle fork according to claim 1, characterized in that: The mold sand pattern is manufactured using molding. The molding machine has a sand injection pressure of 0.2 Bar to 0.4 Bar and an extrusion pressure of 8 Bar to 12 Bar, with a target compaction rate of 23% to 30%.

9. The integrated casting method for a steering knuckle fork according to claim 1, characterized in that: The shot blasting is performed using a shot blasting machine, the shot blasting time of which is 8-10 minutes, and the diameter of the steel shot used in the shot blasting machine is 1.2mm-1.8mm.

10. The integrated casting method for a steering knuckle fork according to claim 9, characterized in that: The grinding process involves grinding the casting to remove burrs and flash.

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