Spinning forming machining method for high-temperature alloy precision sheet metal part

Abstract

The invention belongs to the technical field of high-temperature alloy processing, and discloses a spinning forming processing method of a high-temperature alloy precision sheet metal part, which comprises the following steps: S1, blank preparation; s2, mold manufacturing; s3, setting spinning parameters; s4, spinning forming is carried out; s5, performing subsequent treatment; according to the technical scheme, the equal-channel angular pressing technology is used for conducting ultra-fine grain treatment on the blank, the element segregation phenomenon in the high-temperature alloy is improved, alloy elements are promoted to be evenly distributed, material plasticity is enhanced, deformation resistance is reduced, the single-time deformation amount in the spinning process can be properly increased, spinning passes are reduced, and the yield of the high-temperature alloy is increased. And the cracking risk caused by multiple times of deformation accumulated stress is reduced, and the success rate of part forming is increased. By establishing a mathematical model among the material performance, the part size and the spinning parameters, parameter setting errors are reduced, the whole technological process has good stability and repeatability, dependence on experience of operators is reduced, and standardized production can be achieved easily.

Description

Technical Field

[0001] This invention relates to the field of high-temperature alloy processing technology, and in particular to a spinning forming method for high-temperature alloy precision sheet metal parts. Background Technology

[0002] High-temperature alloys are alloy materials that can maintain good mechanical properties at high temperatures. They possess excellent high-temperature resistance, corrosion resistance, oxidation resistance, and high strength, and are widely used in high-end fields such as aerospace, energy, and military. High-temperature alloy precision sheet metal parts are key components in these fields, and their manufacturing quality directly affects the performance and reliability of the entire equipment.

[0003] Spin forming is a processing method that uses rotation and pressure to plastically deform metal sheets, thereby obtaining parts of the desired shape. Compared with traditional processing methods such as forging and casting, spin forming has advantages such as high material utilization, good mechanical properties of parts, and suitability for forming complex curved surfaces. It has been applied to some extent in the manufacturing of high-temperature alloy precision sheet metal parts.

[0004] However, current spinning forming methods for high-temperature alloy precision sheet metal parts still face many unresolved problems: High-temperature alloys contain various alloying elements, such as chromium, nickel, molybdenum, and niobium, which may lead to compositional segregation during smelting and rolling. This segregation results in uneven mechanical properties of the material, and during spinning, localized areas may experience inconsistent deformation due to varying deformation resistance, leading to defects such as wrinkles and bulges, affecting the consistency of part quality. Furthermore, high-temperature alloys have a high elastic modulus, and the release of residual stress after spinning can cause springback, resulting in fluctuations in dimensional accuracy. Moreover, the determination of process parameters currently relies heavily on operator experience, lacking scientific theoretical guidance and precise control methods, making it difficult to guarantee the stability of processing quality and hindering standardized, large-scale production. Summary of the Invention

[0005] The present invention aims to provide a spinning forming method for high-temperature alloy precision sheet metal parts, in order to solve the problems of poor forming quality, low efficiency and strong dependence on operators of high-temperature alloy precision sheet metal parts mentioned in the background art, and to achieve high-quality, high-efficiency and low-cost manufacturing of high-temperature alloy precision sheet metal parts.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] S1. Blank preparation: Cold-rolled sheet is selected as the blank. The blank is subjected to ultra-fine crystallization treatment using equal channel corner extrusion technology to refine the blank grains to 1-5μm. Laser cleaning is used to remove oxide scale and oil stains from the blank surface. A high-temperature anti-oxidation coating is sprayed on the blank surface. The blank is cut into a circle or an irregular shape that matches the unfolded shape of the part.

[0008] S2. Mold manufacturing: The mold includes a core mold, a tail top and a pressure ring. The core mold and the rotating wheel are made of gradient functional materials. The rotating wheel adopts a hollow water-cooled structure. The surface of the core mold is coated with a diamond-like coating.

[0009] S3. Spinning parameter setting: By establishing a mathematical model between material properties, part size and spinning parameters through material hardness, plasticity characteristics and part diameter and wall thickness parameters, the optimal combination of heating temperature, spindle speed and spinning wheel feed speed is calculated.

[0010] S4. Spin forming: The blank from S1 is placed between the core mold and the tail, and pressed by the pressure ring to ensure that the blank and the core mold are concentric and the eccentricity is ≤0.03mm; Differential temperature is applied to different areas of the blank using zoned induction heating technology, with the temperature difference controlled between 50-100℃, and the deformation amount of each pass is dynamically distributed. The deformation amount of the first pass is 5%-10%, the deformation amount of the middle passes gradually increases to 20%-25%, and the deformation amount of the last 2-3 passes is 3%-5%, to obtain the molded part.

[0011] S5. Subsequent processing: After spinning, the molded parts in S4 are subjected to a stepped aging treatment of 650℃ for 2 hours and then 720℃ for 4 hours. Finally, the surface defects of the molded parts are polished by magnetorheological polishing.

[0012] Preferably, the extrusion pressure of the equal channel corner extrusion technology is 600-1200MPa, and the channel corner angle is 90°-120°.

[0013] Preferably, the diameter error of the cut blank is controlled within ±0.1mm, and the edges are smooth and burr-free.

[0014] Preferably, the high-temperature antioxidant coating is an Al-Si-Y coating, and the thickness of the high-temperature antioxidant coating is 5-20 μm.

[0015] Preferably, in the hollow water-cooled structure of the rotary wheel, the flow rate of the cooling water is 1-5 L / min, and the inlet water temperature is ≤30℃.

[0016] Preferably, the surface roughness of the core mold is ≤Ra0.8μm, the mold size tolerance is 1-2 grades higher than that of the workpiece, and thermal expansion compensation is reserved.

[0017] Preferably, the zoned induction heating technology uses an infrared thermal imager to monitor the temperature in real time, with a temperature monitoring accuracy of ±5℃.

[0018] Preferably, the heating rate of the stepped aging treatment is 5-10℃ / min, and the cooling rate is 3-5℃ / min.

[0019] The beneficial effects of this technical solution compared to existing technologies are as follows:

[0020] (1) This technical solution uses cold-rolled steel and employs equal-channel corner extrusion technology to perform ultra-fine crystallization treatment on the billet, refining the grains to 1-5μm. This improves the element segregation phenomenon in high-temperature alloys, promotes the uniform distribution of alloying elements, enhances the plasticity of the material, and reduces the deformation resistance. This allows for an appropriate increase in the amount of deformation per pass during spinning, reduces the number of spinning passes, lowers the risk of cracking caused by accumulated stress from multiple deformations, and improves the success rate of part forming. At the same time, laser cleaning removes surface impurities, and a high-temperature anti-oxidation coating provides protection, making the properties of different areas of the material more consistent and reducing defects such as wrinkling and bulging caused by performance fluctuations during spinning.

[0021] (2) By selecting Al-Si-Y coating as the high-temperature anti-oxidation coating, it has good high-temperature stability. Under the heating temperature required for spinning and the high-temperature environment in which the parts are in service, the coating structure is not prone to significant grain coarsening or phase transformation, and can maintain structural integrity. Yttrium can also inhibit the interfacial cracking between the oxide film and the coating, reduce the peeling phenomenon of the oxide film caused by thermal cycling, extend the effective protective life of the coating, and thus improve the overall service life of the parts.

[0022] (2) By selecting graded functional materials to make the mold, and adopting a hollow water-cooled structure for the rotating wheel and spraying a diamond-like coating on the core mold surface, the high temperature resistance, wear resistance and service life of the mold are improved, and the mold replacement frequency and production cost are reduced. By adopting a higher dimensional tolerance grade and reserving thermal expansion compensation, the fitting error caused by temperature changes is reduced, and the mold repair frequency is reduced.

[0023] (3) By establishing a mathematical model between material properties, part dimensions, and spinning parameters, the optimal spinning parameters can be scientifically calculated, reducing errors in parameter setting. The use of zoned induction heating technology and dynamic allocation of deformation amounts in each pass achieves uniform deformation of the billet, improving the dimensional accuracy and forming quality of the parts. This results in better stability and repeatability of the entire process, reducing reliance on operator experience and facilitating standardized production.

[0024] (4) Step-age aging treatment can significantly reduce residual stress inside parts, reduce springback, and improve the dimensional stability of parts. The ultrafine grain structure of the material and the uniformly precipitated strengthening phase work together to enhance the high-temperature strength and fatigue life of parts, and improve the reliability of parts during use. The heating rate of the step-age aging treatment is 5-10℃ / min, and the cooling rate is 3-5℃ / min. The reasonable heating rate provides sufficient time for the nucleation and growth of the strengthening phase, which helps to form a finer and more reasonably distributed precipitate phase structure; while the appropriate cooling rate can inhibit the coarsening of the strengthening phase and maintain its fine morphology, thereby maximizing the strengthening effect of aging treatment, so that the material can obtain high strength while taking into account good toughness and plasticity. Magnetorheological polishing treatment effectively removes surface defects, improves the surface finish of parts, and meets the requirements of high-end fields for the surface quality of parts. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the processing of the present invention; Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments:

[0027] like Figure 1 The method for spinning high-temperature alloy precision sheet metal parts shown includes the following steps:

[0028] S1. Billet Preparation: GH4169 high-temperature alloy cold-rolled sheet is selected as the billet. Due to the cold working process during rolling, the grains are refined, the microstructure is denser, and it possesses higher strength and better surface quality, providing a good foundation for subsequent processing. The billet undergoes ultra-fine crystallization treatment using equal-channel corner extrusion technology. This technology involves placing the billet into a mold composed of two equal-section, mutually perpendicular channels. Under pressure, the billet moves from one channel to the other, undergoing intense shear plastic deformation at the corner. This deformation generates a large number of dislocations within the billet. As deformation progresses, these dislocations continuously multiply, move, and interact. This process allows atoms to gain sufficient energy for further diffusion. Alloy elements that were originally concentrated in certain areas due to segregation can gradually migrate to areas with lower composition through atomic diffusion, thereby improving the overall uniformity of the alloy composition. Furthermore, it breaks down and refines the original coarse grains. The equal-channel corner extrusion technology uses an extrusion pressure of 600 MPa and a channel corner angle of 90° to refine the billet grains, resulting in an ultrafine-grained structure of 1-3 μm. This ultrafine-grained structure significantly improves the plasticity of high-temperature alloys, reduces deformation resistance, decreases the risk of cracking during spinning, and increases the amount of deformation per pass while reducing the number of spinning passes. Laser cleaning utilizes a high-energy laser beam to irradiate the billet surface. Oxide scale and oil absorb the laser energy and rapidly heat to their evaporation temperature, instantly evaporating or peeling off, achieving surface purification and preventing impurities from being pressed into the surface and forming defects during spinning. An Al-Si-Y high-temperature anti-oxidation coating with a thickness of 5 μm is sprayed onto the billet surface. The Y element promotes the formation of a dense oxide film from Al and Si elements in the coating at high temperatures, isolating the billet from air contact and inhibiting oxidation reactions during subsequent heating and spinning processes, thus reducing oxide scale formation. The billet is cut into circular shapes with a diameter error controlled within ±0.05 mm, and the edges are smooth and burr-free.

[0029] S2. Mold Manufacturing: The mold comprises a core mold, a tail ejector, and a pressure ring. The core mold and rotating wheel are made of graded functional materials (JDMs). The composition and properties of the JDMs exhibit a continuous gradient along the thickness direction, ensuring that the core mold and rotating wheel maintain good mechanical properties and high-temperature resistance even at high temperatures. The rotating wheel employs a hollow water-cooled structure. The circulating cooling water within the rotating wheel effectively removes the heat generated during friction with the workpiece. The cooling water flow rate is 1-5 L / min, and the inlet water temperature is ≤30℃. A diamond-like carbon (DLC) coating is sprayed onto the core mold surface using physical vapor deposition (PVD), resulting in a surface roughness of Ra 0.6 μm. This reduces friction and wear between the core mold and the workpiece, extending the core mold's service life. The mold dimensional tolerances are one grade higher than the workpiece tolerances, and allowances are provided for thermal expansion compensation.

[0030] S3. Spinning Parameter Setting: The hardness and plasticity of the material determine its deformation capacity during spinning, while the diameter and wall thickness of the part affect the force and energy requirements during spinning. A mathematical model is established to connect material properties, part dimensions, and spinning parameters. The optimal spinning parameters for GH4169 high-temperature alloy cold-rolled sheets under each combination are recorded (based on the criteria of no cracking and dimensional accuracy meeting standards after forming). The least squares method is used to fit the experimental data to obtain regression coefficients. The model accuracy is verified using 10% of the experimental data. If the predicted parameters deviate from the actual optimal parameters by more than ±5%, a neural network algorithm is used for further optimization. The input layer has four parameters (material hardness H, plastic elongation δ, part diameter D, and wall thickness t), the output layer has three spinning parameters (heating temperature T, spindle speed n, and spinning wheel feed speed v), and there are two hidden layers (10 neurons per layer).

[0031] The correlation model between spinning parameters and input parameters is constructed based on multiple regression analysis, and the basic expression is:

[0032]

[0033] in:

[0034] k1~k 12 These are the regression coefficients;

[0035] c1-c3 is a constant term;

[0036] Input parameters need to be standardized (e.g., hardness H is in HRC, elongation δ is a percentage, diameter D and wall thickness t are in mm).

[0037] Considering the risks of material oxidation and grain growth, the base temperature needs to be adjusted.

[0038] T 修正 =T-α·δ+β·t

[0039] α: Plasticity compensation coefficient (value ranges from 0.5 to 1.2; the better the plasticity, the greater the correction).

[0040] β: Wall thickness compensation coefficient (values ​​range from 5 to 10; the greater the wall thickness, the higher the temperature is required to ensure uniform deformation).

[0041] Taking into account the influence of part diameter on centrifugal force, the spindle speed correction formula is as follows:

[0042]

[0043] D0: Reference diameter (usually 200mm);

[0044] When D>500mm, an additional safety factor of 0.8 to 0.9 is required (to avoid excessive centrifugal force).

[0045] Based on the balance between deformation and frictional heat generation, the feed rate correction formula is as follows:

[0046]

[0047] Based on an elongation of 20% and a wall thickness of 10mm, the better the plasticity (the larger δ) and the thinner the wall thickness (the smaller t), the feed rate can be appropriately increased.

[0048] By changing the regression coefficients, this method can be applied to different grades of high-temperature alloys. The optimal combination of heating temperature, spindle speed, and rotary feed rate is calculated to ensure the billet is in the best deformation state during spinning, guaranteeing the forming quality and dimensional accuracy of the parts. Based on the hardness and plasticity of GH4169, as well as the part's diameter (300mm) and wall thickness (4mm), the optimal heating temperature is calculated to be 897℃, the spindle speed to be 617r / min, and the rotary feed rate to be 228mm / min. For parts with complex shapes, a zoned heating strategy is required, employing differentiated parameters for different regions.

[0049] S4. Spin Forming: The processed blank is placed between the mandrel and the tailstock, and pressed together by a pressure ring to ensure concentricity between the blank and the mandrel with an eccentricity of 0.02mm. Differential temperatures are applied to different areas of the blank using zoned induction heating technology with multiple independently controlled induction coils. Areas with high curvature and large deformation are heated to higher temperatures, while areas with low curvature and small deformation are heated to lower temperatures, with the temperature difference controlled within 50℃. Temperature is monitored in real-time using an infrared thermal imager with an accuracy of ±3℃. The deformation amount is dynamically allocated for each pass. The first pass has a deformation amount of 5% to eliminate residual stress within the blank and stabilize its structure. The deformation amount in intermediate passes gradually increases to 20%, achieving the main deformation process and bringing the blank closer to the shape and size of the part. The final two passes have a deformation amount of 3% each, used for finishing the part, correcting dimensional deviations, and obtaining the formed part.

[0050] S5. Post-processing: After spinning, the molded parts from S4 undergo a stepped aging treatment, holding at 650℃ for 2 hours and then at 720℃ for 4 hours. The heating rate is 5℃ / min, and the cooling rate is 3℃ / min. At 650℃, some reinforcing phases precipitate inside the material, initially eliminating some residual stress. Upon heating to 720℃, the reinforcing phases further precipitate and distribute evenly, reducing residual stress by 60%-80%, reducing springback, stabilizing part dimensions, and improving mechanical properties. Finally, magnetorheological polishing is applied to the surface defects of the molded parts. Magnetorheological polishing utilizes the rheological properties of magnetorheological fluid under a magnetic field to perform micro-cutting on the surface of the molded parts. The "flexible grinding head" formed by the magnetorheological fluid in the magnetic field can conform to the shape of the part surface, precisely repairing surface defects. After 40 minutes, the surface roughness of the molded parts reaches Ra0.02μm.

[0051] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for spin forming of high-temperature alloy precision sheet metal parts, characterized in that... This includes the following steps: S1. Blank preparation: Cold-rolled sheet is selected as the blank. The blank is subjected to ultra-fine crystallization treatment using equal channel corner extrusion technology to refine the blank grains to 1-5μm. Laser cleaning is used to remove oxide scale and oil stains from the blank surface. A high-temperature anti-oxidation coating is sprayed on the blank surface. The blank is cut into a circle or an irregular shape that matches the unfolded shape of the part. S2. Mold manufacturing: The mold includes a core mold, a tail top and a pressure ring. The core mold and the rotating wheel are made of gradient functional materials. The rotating wheel adopts a hollow water-cooled structure. The surface of the core mold is coated with a diamond-like coating. S3. Spinning parameter setting: By using the material hardness, plasticity, and the diameter and wall thickness of the part, a mathematical model is established between the material properties, part size and spinning parameters, and the optimal combination of heating temperature, spindle speed and spinning wheel feed speed is calculated. S4. Spin forming: The blank from S1 is placed between the core mold and the tail, and pressed by the pressure ring to ensure that the blank and the core mold are concentric and the eccentricity is ≤0.03mm; Differential temperature is applied to different areas of the blank using zoned induction heating technology, with the temperature difference controlled between 50-100℃, and the deformation amount of each pass is dynamically distributed. The deformation amount of the first pass is 5%-10%, the deformation amount of the middle passes gradually increases to 20%-25%, and the deformation amount of the last 2-3 passes is 3%-5%, to obtain the molded part. S5. Subsequent processing: After spinning, the molded parts in S4 are subjected to a stepped aging treatment of 650℃ for 2 hours and then 720℃ for 4 hours. Finally, the surface defects of the molded parts are polished by magnetorheological polishing.

2. The spinning forming method for high-temperature alloy precision sheet metal parts as described in claim 1, characterized in that: The extrusion pressure of the equal channel corner extrusion technology is 600-1200MPa, and the channel corner angle is 90°-120°.

3. The spinning forming method for high-temperature alloy precision sheet metal parts as described in claim 1, characterized in that: The diameter error of the cut blank is controlled within ±0.1mm, and the edges are smooth and burr-free.

4. The spinning forming method for high-temperature alloy precision sheet metal parts as described in claim 1, characterized in that: The high-temperature antioxidant coating is an Al-Si-Y coating, and the thickness of the high-temperature antioxidant coating is 5-20μm.

5. The spinning forming method for high-temperature alloy precision sheet metal parts as described in claim 1, characterized in that: In the hollow water-cooled structure of the rotary wheel, the flow rate of cooling water is 1-5 L / min, and the inlet water temperature is ≤30℃.

6. The spinning forming method for high-temperature alloy precision sheet metal parts as described in claim 1, characterized in that: The surface roughness of the core mold is ≤Ra0.8μm, the mold size tolerance is 1-2 grades higher than that of the workpiece, and thermal expansion compensation is reserved.

7. The spinning forming method for high-temperature alloy precision sheet metal parts as described in claim 1, characterized in that: The zoned induction heating technology monitors the temperature in real time using an infrared thermal imager, with a temperature monitoring accuracy of ±5℃.

8. The spinning forming method for high-temperature alloy precision sheet metal parts as described in claim 1, characterized in that: The step-age treatment has a heating rate of 5-10℃ / min and a cooling rate of 3-5℃ / min.

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