Short-process near-net forming method for double-curvature thin-walled ring forging and double-curvature thin-walled ring forging

Abstract

The invention provides a short-process near-net forming method for a hyperbolic thin-walled ring forging and a hyperbolic thin-walled ring forging, comprising: determining the initial size and geometric shape of an unfolded blank required for making the hyperbolic ring forging; determining the maximum cross-sectional shrinkage rate of closing at room temperature according to a design drawing of a hyperbolic part; designing a room-temperature closing die based on the determined maximum cross-sectional shrinkage rate of closing at room temperature; using a plate rolling machine to press a quenched blank rolled plate to shape it into a rolled blank with a preset diameter; welding the rolled seam of the rolled blank to obtain a cylindrical blank; using a closing die to process the cylindrical blank into a hyperbolic ring forging blank; sending the hyperbolic ring forging blank into a heat treatment furnace for artificial aging; placing the hyperbolic ring forging blank after artificial aging on a CNC vertical lathe for processing, and removing the reserved processing allowance to obtain a final hyperbolic thin-walled ring forging.

Description

Technical Field

[0001] The invention relates to the technical field of metal forging forming, in particular to a short-process near-net forming method for a double-curvature thin-walled ring forging and the double-curvature thin-walled ring forging. Background Art

[0002] In order to improve the material strength following the traditional aluminum alloy "forging billet-piercing-ring rolling-turning" route, the turning process is divided into "rough turning and fine turning", during which quenching heat treatment and aging are added. In a realistic environment, the cooling amount of the quenched core of a large ring forging is significantly smaller than that of the surface, resulting in low mechanical properties of the core, while the core is ultimately used for part performance evaluation, and the surface is removed by turning. For complex thin-walled hyperbolic ring forgings, the existing technology is designed as a large pre-forged billet, which requires sufficient turning allowance in the thickness direction, which will increase the risk of material hardenability. At the same time, deformation during quenching heat treatment destroys the dimensional accuracy of the blank, and deformation exceeding tens of millimeters can easily cause the entire piece to be scrapped.

[0003] Patent document CN110614295B (application number: CN201910957568.5) discloses a polygonal ring forging top rounding process, and the process is as follows: (1) preparing a polygonal ring forging top rounding device; (2) when the wall thickness of the ring forging is less than 200 mm, the polygonal ring forging does not need to be heated during the top rounding, and the polygonal ring forging is top rounded by the top rounding device; when the wall thickness of the ring forging is not less than 200 mm, if the polygonal ring forging has not been heat treated before the top rounding, then the polygonal ring forging needs to be heated to the normalizing temperature first, and then the polygonal ring forging can be top rounded by the top rounding device; if the polygonal ring forging has been heat treated before the top rounding, then the polygonal ring forging needs to be heated to the tempering temperature first, and then the polygonal ring forging can be top rounded by the top rounding device; after the top rounding, if it is warped, it needs to be flattened by a press, and if it has been heat treated, it needs to be stress relief annealed.

[0004] The traditional aluminum alloy ring forging manufacturing method adopts the hot forming process of "forging-piercing-ring rolling-turning" as the main route. The goal is to obtain an intermediate blank at a certain heating temperature. It is a typical volume forming method. After the blank is obtained, a large amount of material is removed by machining. Although it is extremely wasteful, the square, cylindrical, and ring-shaped intermediate blanks are relatively simple, but they will not change significantly with the increase in the complexity of the final parts. Therefore, even if there is a lot of waste, the operation mode has been maintained for a long time. In the actual engineering application environment, due to the increasingly urgent demand for low-cost manufacturing of launch vehicles, the traditional ring rolling method cannot meet the requirements of green, environmental protection, short process, and near-net forming from multiple links such as blank making, forging, and rolling. Summary of the invention

[0005] In view of the defects in the prior art, the object of the present invention is to provide a short-process near-net forming method for a hyperbolic thin-walled ring forging and a hyperbolic thin-walled ring forging.

[0006] A short-process near-net forming method for a double-curvature thin-walled ring forging provided by the present invention comprises:

[0007] Step S1: determining the initial size and geometric shape of the unfolded blank required for manufacturing the double curvature ring forging;

[0008] Step S2: determining the maximum cross-sectional shrinkage rate of the closing at room temperature according to the design drawing of the hyperbolic part;

[0009] Step S3: designing a room temperature closing mold based on the determined maximum cross-sectional shrinkage rate of the closing at room temperature;

[0010] Step S4: The quenched blank is rolled using a plate rolling machine to be formed into a rolled blank with a preset diameter;

[0011] Step S5: welding the rolled blank to obtain a cylindrical blank;

[0012] Step S6: using a closing die to process the cylindrical blank into a double curvature ring forging blank;

[0013] Step S7: sending the double curvature ring forging blank into a heat treatment furnace for artificial aging;

[0014] Step S8: placing the artificially aged hyperbolic ring forging blank on a CNC vertical lathe for processing, and removing the reserved processing allowance to obtain a final hyperbolic thin-walled ring forging.

[0015] Preferably, the step S1 adopts: when a rectangular blank is used, the length of the rectangle should not be less than the circumference of the neutral layer of the ring forging; when a fan-shaped annular blank is used, the outer arc length should not be less than the open size of the ring forging.

[0016] Preferably, the blank is aluminum alloy.

[0017] Preferably, the step S2 adopts:

[0018]

[0019] in, Indicates the maximum cross-sectional shrinkage; Indicates the theoretical outer diameter of the blank after winding; Indicates the theoretical minimum outer diameter of the blank after closing.

[0020] Preferably, the step S3 adopts: checking the strength and stiffness of the room temperature closing mold through room temperature closing forming finite element simulation, and obtaining the closing forming and springback deformation laws; comparing the ring forging blank obtained by the current finite element simulation with the theoretical design drawing, if the blank cannot envelope the design model, further optimizing the mold surface design, and performing finite element simulation again; iterating multiple times in this way to obtain the optimized closing mold design model; and carrying out closing mold processing according to the optimized mold design results.

[0021] Preferably, the step S5 adopts: the roll seam of the rolled round blank is welded by means of stir friction welding to obtain a cylindrical blank.

[0022] Preferably, the step S6 adopts: placing the cylindrical blank on the press table of a large-table press, fixing the closing mold on the mold slide of the large-table press, and the closing process starts with the cylindrical blank contacting the inner surface of the closing mold. As the hydraulic press is loaded, the cylindrical blank gradually fits the mold surface under the external constraint load of the mold, and after the press is unloaded, it rebounds and deforms to obtain a hyperbolic ring forging blank.

[0023] Preferably, the method further includes: before sending the hyperbolic ring forging blank into the heat treatment furnace for artificial aging, scanning the actual profile of the hyperbolic ring forging blank and comparing it with the theoretical part model to verify whether the blank completely envelops the final profile of the part; when the verification is successful, sending the hyperbolic ring forging blank into the heat treatment furnace for artificial aging.

[0024] Preferably, the method further comprises: performing surface treatment and packaging protection treatment on the final double-curvature thin-walled ring forging.

[0025] A hyperbolic thin-walled ring forging provided by the present invention is prepared by the above-mentioned hyperbolic thin-walled ring forging short-process near-net forming method.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The present invention adopts a quenched plate with good plasticity at room temperature, and replaces the original large-scale forging ring complex forming process dominated by hot forming with a short process, room temperature, near-net forming process, which is a new process method that is green, environmentally friendly, cost-reducing, and efficient, and near-net forming;

[0028] 2. The goal of the traditional hot forming forging process is to obtain an intermediate blank at a certain temperature, and obtain a double-curvature thin-walled ring forging based on the intermediate blank by volume forming. The intermediate blank is limited by the forging tool, and its shape is approximately cylindrical, square, circular, etc., and the final profile is only a small piece of it, and a large amount of material needs to be removed later; while the present invention obtains a double-curvature thin-walled ring forging based on the quenched plate by shell forming, achieving a "near net forming" effect;

[0029] 3. The present invention obtains a double-curvature ring forging blank based on a new route of "rolling-welding-room temperature closing" of quenched sheet, eliminating the problems of cumbersome traditional hot forming process, high energy consumption, poor working environment and high safety risks; in practice, the method provided by the present invention can achieve at least about 30% cost reduction and more than 25% efficiency improvement;

[0030] 4. The present invention reduces the forging material to 1 / 2-1 / 3 of the traditional material by converting the traditional intermediate blank into a quenched plate, and improves the material utilization rate by 50%-67%. After the forging material is reduced, the forging is quenched more thoroughly, the cooling rate is higher, and the supersaturated solid solution is fully precipitated during aging, so that the service performance of the forging is greatly improved;

[0031] 5. The quenched plate of the present invention is further plastically deformed into a cone ring forging, which is equivalent to superimposing the dual strengthening effects of "aging strengthening" and "strain strengthening", and the forging performance is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0033] Figure 1 is a flow chart of the method of the present invention;

[0034] Figure 2 A flow chart of the room temperature closing forming process design of the present invention;

[0035] Figure 3 It is a schematic diagram of the original ring rolling process route and the cross section of the forged ring after ring rolling;

[0036] Figure 4 It is a schematic diagram of the short process near-net forming of the hyperbolic thin-walled ring forging of the present invention. DETAILED DESCRIPTION

[0037] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0038] Example 1

[0039] According to a short-process near-net forming method for a hyperbolic thin-walled ring forging provided by the present invention, a product processed by a volume forming method based on an intermediate blank is transformed into a product processed by a shell forming method based on a quenched sheet. The forming performance of the material at high temperature is no longer used, but a quenched sheet with good plasticity at room temperature is used, and the "shell forming" method replaces the "volume forming" method to achieve a "near-net forming" effect; it eliminates the problems of cumbersome traditional hot forming procedures, high energy consumption, poor working environment and high safety risks, and is a green, environmentally friendly, near-net forming new process method; it achieves a cost reduction of about 30% and an efficiency improvement of more than 25%. Among them, the thin wall in the thin-walled ring forging mainly depends on the proportional relationship between the wall thickness and the size. When the ratio of the wall thickness to its minimum characteristic size is less than 2%, it is considered to be a thin wall.

[0040] According to the present invention, a short-process near-net forming method for a double-curvature thin-walled ring forging is provided. Figure 1 As shown, including:

[0041] Step S1: designing the size of the double curvature ring forging blank;

[0042] In this embodiment, a rectangular blank is used to maximize the material utilization rate; the length of the rectangle should not be less than the circumference of the neutral layer of the ring forging, and considering the machining allowance and forming springback, the process allowance in the thickness direction is set to not exceed 15 mm on one side to improve the material utilization rate;

[0043] When using fan-shaped ring blanks, the outer arc length should not be less than the expanded size of the ring forging's largest opening.

[0044] In this embodiment, 10 mm is set on one side.

[0045] Step S2: designing the maximum cross-sectional shrinkage rate of the room temperature closing according to the design drawing of the hyperbolic part;

[0046] The specific calculation is as follows:

[0047]

[0048] in, Indicates the maximum cross-sectional shrinkage; Indicates the theoretical outer diameter of the blank after winding; Indicates the theoretical minimum outer diameter of the blank after closing. Generally, the shrinkage rate of the closing section at room temperature is not more than 30%.

[0049] In this embodiment, the maximum diameter of the ring forging is 3800 mm, the minimum diameter is 3000 mm, and the cross-sectional shrinkage is 21%.

[0050] Step S3: designing a room temperature closing mold;

[0051] like Figure 2 As shown, in this embodiment, a closing die design model is designed, and the current closing die design model is subjected to finite element simulation analysis to obtain the maximum equivalent stress of the closing die, and the maximum equivalent stress of the closing die does not exceed 1 / 3 of the yield strength of the material, and the strength margin, that is, the difference between the yield strength of the material and the maximum equivalent stress, is not less than 3; if the requirements are not met, return to redesign the closing die; if the requirements are met, perform the next step of profile optimization; through room temperature closing forming finite element simulation, obtain the closing forming and springback deformation law, that is, different closing die profiles and closing height and other forming parameters; use the closing die profile as the initial load to perform forming simulation to obtain the initial ring forging blank; compare the initial ring forging blank with the theoretical design drawing, and when the ring forging blank cannot wrap the theoretical design drawing, reversely compensate the closing die design model according to the profile discrete point deviation value, update the closing die design model, and repeatedly trigger the execution until the ring forging blank can wrap the theoretical design drawing to obtain the optimized closing die design model.

[0052] According to the optimized mold design results, carry out the closing mold processing;

[0053] Step S4: rolling the quenched blank into a rolled blank with a diameter of D0 by using a plate rolling machine;

[0054] In this embodiment, T351 aluminum alloy rolled plate is used;

[0055] Step S5: welding the drum seams to obtain a cylindrical blank;

[0056] In this embodiment, the rolled blank is subjected to stir friction welding or other welding methods to obtain a cylindrical blank, which will be used for room temperature closing;

[0057] Step S6: forming the cylinder.

[0058] The cylindrical closing forming process is to place the cylindrical blank on the press table, using a conventional large-table press, which is composed of a slide, a table, a hydraulic cylinder, etc. The closing die is fixed on the die slide, and the closing process starts when the cylindrical blank contacts the inner surface of the closing die. As the hydraulic press is loaded, the cylindrical blank gradually fits the die surface under the external constraint load of the die, and after the press is unloaded, it rebounds and deforms to obtain a double curvature ring forging blank;

[0059] Step S7: Scan the actual profile of the double curvature ring forging blank and compare it with the theoretical model to verify whether the blank completely envelops the final profile of the part. If the verification fails, further shrink the mouth by increasing the overall downward pressure of the closing die. Under normal circumstances, the previous finite element simulation work can ensure that the actual profile envelops the final part model.

[0060] Step S8: sending the double curvature ring forging blank into a heat treatment furnace for artificial aging to improve the material strength.

[0061] Step S9: placing the aged hyperbolic blank on a CNC vertical lathe, processing the inner and outer surfaces of the hyperbolic ring forging blank, removing the reserved processing allowance, and obtaining the final hyperbolic thin-walled ring forging.

[0062] Step S10: surface treatment / packaging protection.

[0063] like Figure 2 As shown in the figure, the room temperature closing forming process design simulation optimization process, through finite element simulation calculation, check the mold strength and stiffness; if the strength or stiffness does not meet the requirements, return to redesign the mold structure. Obtain the closing forming and springback deformation rules. If the simulation results show that the blank cannot envelop the theoretical model after springback, return to redesign the mold surface. The simulation results are used to guide the mold surface design.

[0064] like Figure 3 As shown in the figure, in the traditional hot forming forging process, hot forming needs to keep the forgings at a hot working temperature of 350-400°C, and the material utilization rate is the cross-sectional area of ​​2 divided by the cross-sectional area of ​​1, where 1 is the cross-sectional area of ​​a large ring-rolled thick-walled blank, and 2 is the cross-sectional area of ​​a hyperbolic thin-walled ring forging. It can be seen that the original ring rolling route has a lengthy process flow, serious material waste, and an extremely low utilization rate of less than 20%-30%.

[0065] like Figure 4 As shown, the short process near net forming of the double curvature thin-walled ring forging of the present invention is shown in the figure. The raw material of this embodiment is 2219 aluminum alloy, the plate heat treatment state is T351 state, the turning allowance in the thickness direction is only 10mm, and the material utilization rate reaches about 60%, highlighting the short process, room temperature, near net forming characteristics of the present invention.

[0066] A hyperbolic thin-walled ring forging provided by the present invention is prepared by the above-mentioned hyperbolic thin-walled ring forging short-process near-net forming method.

[0067] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A short-process near-net forming method for a double-curvature thin-walled ring forging, characterized in that: include: Step S1: determining the initial size and geometric shape of the unfolded blank required for manufacturing the double curvature ring forging; Step S2: determining the maximum cross-sectional shrinkage rate of the closing at room temperature according to the design drawing of the hyperbolic part; Step S3: designing a room temperature closing mold based on the determined maximum cross-sectional shrinkage rate of the closing at room temperature; Step S4: The quenched blank is rolled using a plate rolling machine to be formed into a rolled blank with a preset diameter; Step S5: welding the rolled blank to obtain a cylindrical blank; Step S6: using a closing die to process the cylindrical blank into a double curvature ring forging blank; Step S7: sending the double curvature ring forging blank into a heat treatment furnace for artificial aging; Step S8: placing the artificially aged hyperbolic ring forging blank on a CNC vertical lathe for processing, and removing the reserved processing allowance to obtain a final hyperbolic thin-walled ring forging; The step S3 adopts: Step S3.1: constructing a closing mold design model; Step S3.2: Perform finite element simulation analysis on the current closing mold design model to obtain the maximum equivalent stress and strength margin of the closing mold; when the obtained maximum equivalent stress and strength margin of the closing mold do not meet the preset requirements, repeatedly trigger steps S3.1 to S3.2 until the maximum equivalent stress and strength margin of the closing mold meet the preset requirements; Step S3.3: Obtain the closing forming and springback deformation rules through room temperature closing forming finite element simulation; obtain the ring forging blank based on the current closing die design model and the closing forming and springback deformation rules; Step S3.4: Compare the current ring forging blank with the theoretical design drawing. When the ring forging blank cannot wrap the theoretical design drawing, reverse compensation is performed on the closing die design model according to the discrete point deviation value of the closing die design model surface to obtain the compensated closing die design model. Repeat steps S3.2 to S3.4 until the ring forging blank can wrap the theoretical design pattern, and obtain the optimized closing die design model; The step S6 adopts: placing the cylindrical blank on the press table of a large-table press, fixing the closing mold on the mold slide of the large-table press, and the closing process starts when the cylindrical blank contacts the inner surface of the closing mold. As the hydraulic press is loaded, the cylindrical blank gradually fits the mold surface under the external constraint load of the mold, and after the press is unloaded, it rebounds and deforms to obtain a hyperbolic ring forging blank.

2. The short-process near-net forming method of a double-curvature thin-walled ring forging according to claim 1 is characterized in that: The step S1 adopts: when a rectangular blank is used, the length of the rectangle should not be less than the circumference of the neutral layer of the ring forging; when a fan-shaped ring blank is used, the outer arc length should not be less than the open size of the ring forging.

3. The short-process near-net forming method of a double-curvature thin-walled ring forging according to claim 1 is characterized in that: The blank is made of aluminum alloy.

4. The short-process near-net forming method of a double-curvature thin-walled ring forging according to claim 1 is characterized in that: The step S2 adopts: in, Indicates the maximum cross-sectional shrinkage; Indicates the theoretical outer diameter of the blank after winding; Indicates the theoretical minimum outer diameter of the blank after closing.

5. The short-process near-net forming method of a double-curvature thin-walled ring forging according to claim 1 is characterized in that: The step S5 comprises: performing welding processing on the roll seam of the rolled round blank by means of stir friction welding to obtain a cylindrical blank.

6. The short-process near-net forming method of a double-curvature thin-walled ring forging according to claim 1, characterized in that: The method also includes: before sending the hyperbolic ring forging blank into the heat treatment furnace for artificial aging, scanning the actual profile of the hyperbolic ring forging blank and comparing it with the theoretical part model to verify whether the blank completely envelops the final profile of the part; when the verification is successful, sending the hyperbolic ring forging blank into the heat treatment furnace for artificial aging.

7. The short-process near-net forming method of a double-curvature thin-walled ring forging according to claim 1 is characterized in that: The method further comprises: performing surface treatment and packaging protection treatment on the final double curvature thin-walled ring forging.

8. A double curvature thin-walled ring forging, characterized in that: The forging is prepared by the short-process near-net forming method of the double-curvature thin-walled ring forging as described in any one of claims 1 to 7.

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