Manufacturing process for improving comprehensive performance of large thick-walled 2A14 conical part

Abstract

The application provides a manufacturing process for improving the comprehensive performance of large thick-wall 2A14 conical parts, which comprises the following steps: A) blanking by forging: A1) preparing materials, A2) forging and punching, and A3) hole expanding; B) machining before quenching; C) heat treatment: C1) quenching heat treatment, C2) aging heat treatment, and C3) annealing heat treatment; and D) part machining. In the blanking by forging, the method of 'rotary upsetting + lubricating one end of the cylindrical blank and not lubricating the other end' is used to realize the blanking process from the cylindrical blank to the circular truncated cone blank; the method of 'punching + segmented hole expanding' is used to realize the blanking process from the circular truncated cone blank to the conical ring blank; the method of reducing the metal material quantity and the wall thickness of the forging blank is used to improve the deformation degree of the grains at the 1 / 2 wall thickness and then improve the elongation; and the double residual stress reduction method of'machining thinning before quenching + final stress relief annealing' is used to reduce the residual stress level of the special-shaped forging, so as to reduce the cracking risk during the machining of the finished product.

Description

Technical Field

[0001] This invention relates to the field of metal material processing, and in particular to a manufacturing process for improving the overall performance of large, thick-walled 2A14 tapered parts. Background Technology

[0002] Currently, 2A14 aluminum alloy is a high-strength aluminum alloy, especially for large-sized irregular forgings with a wall thickness ≥150mm (such as...). Figure 1 As shown, aluminum alloy forgings are generally manufactured using die forging, but this significantly increases the cost of mold manufacturing (ranging from tens of thousands to hundreds of thousands of yuan) and the mold procurement cycle. While free forging can significantly reduce mold manufacturing costs, it is extremely difficult to manufacture, and the following problems frequently arise during production: First, how to solve the problem of free forging of irregularly shaped parts; second, insufficient grain deformation at half the wall thickness of large, thick-walled irregularly shaped parts easily leads to unqualified elongation, requiring a solution to the performance deficiency at half the wall thickness; third, the difficulty in eliminating quenching residual stress in large, thick-walled irregularly shaped parts, which easily leads to workpiece cracking during machining due to uneven stress release, requiring a solution to the machining cracking problem of large, thick-walled irregularly shaped parts. Therefore, how to use economical means such as free forging to manufacture large, thick-walled irregularly shaped forgings with qualified performance and resistant to machining cracking is a major challenge in the field of aluminum alloy forging material preparation. Summary of the Invention

[0003] In view of this, the present invention provides a manufacturing process for improving the overall performance of large, thick-walled 2A14 tapered parts. The manufacturing process provided by the present invention addresses the three major technical challenges mentioned above and reduces mold manufacturing costs.

[0004] This invention provides a manufacturing process for improving the overall performance of large, thick-walled 2A14 tapered components, comprising the following steps:

[0005] A) Forging billet preparation:

[0006] A1) Material preparation: Use round ingots for material preparation, and determine the diameter and length of the round ingots;

[0007] A2) Forging and punching: The round ingot from step A1) is upset, wherein the last upset is a rotary upset, and during the last upset process, the upper end of the cylindrical billet is lubricated with oil, while the lower end is not lubricated, thereby obtaining a frustum billet; then punching is performed to obtain a frustum billet with holes.

[0008] A3) Hole enlargement: The perforated frustum blank is enlarged in sections to obtain a conical ring blank;

[0009] B) Machining before quenching:

[0010] The conical ring blank obtained in step A) is machined to the dimensions required by the drawing using a CNC lathe; the dimensions are based on a single-sided allowance of 5-10mm on the finished workpiece.

[0011] C) Heat treatment:

[0012] C1) Quenching heat treatment:

[0013] The forgings obtained in step B) are subjected to quenching heat treatment. The selection and control principles for various process parameters and methods are as follows:

[0014] Quenching temperature: The quenching temperature is 5-10℃ lower than the overheating temperature of the material, and the quenching temperature tolerance is ±3℃ or ±4℃.

[0015] Air holding time: The holding time is determined based on the maximum heat treatment thickness of the forging billet. The minimum holding time of 120 minutes is taken as the benchmark for wall thickness ≤38mm. For every 12.7mm increase in wall thickness, the holding time is increased by 30 minutes. Where the increase in wall thickness is less than 12.7mm, it is calculated as 12.7mm.

[0016] Material spacing: The material spacing must be greater than or equal to the maximum heat treatment thickness of the forging billet;

[0017] Quenching water temperature: The temperature difference between water before and after quenching shall not exceed 10℃, and the quenching water temperature shall be ≤30℃;

[0018] Transfer time: Control transfer time ≤ 15s;

[0019] Immersion time: Control the immersion time to at least 2 minutes for every 25 mm of the maximum heat treatment thickness of the forging blank;

[0020] Number of material frame vibrations: The forging should be raised and lowered at least 5 times in water, and should not be exposed above the water surface during the immersion time;

[0021] C2) Aging heat treatment:

[0022] The forgings obtained in step C1) are subjected to aging heat treatment, with the aging heat treatment temperature controlled at 150-180℃ and the time at 5-15h.

[0023] C3) Annealing heat treatment:

[0024] The forgings obtained in step C2) are subjected to annealing heat treatment, with the annealing heat treatment temperature controlled at 190-210℃ and the time at 6-10h.

[0025] D) Machining of parts:

[0026] Based on the part drawing, the forging blank obtained in step C) is machined to the dimensions required by the part drawing.

[0027] Preferably, in step A1), the selection principle for the diameter D and length h of the round ingot is: h / D ratio ≤ 3.

[0028] Preferably, in step A1), the weight of the material is controlled during the material preparation process;

[0029] The principle for controlling the weight of the feed material is as follows: determine the weight of the billet, and then feed the material according to the feeding coefficient of 1.2 to 2.0.

[0030] Preferably, the principle for controlling the feed weight is: based on the alloy's density of 2.8 g / cm³. 3 Determine the weight of the billet, and then feed it according to the feeding coefficient of 1.2 to 2.0.

[0031] Preferably, in step A2), the upsetting and drawing can be two upsettings and one drawing, three upsettings and two drawing, or four upsettings and three drawing.

[0032] Preferably, in step A2), the selection principle for the punch diameter during the punching process is as follows: (1) the punch diameter is smaller than the hole diameter after the small end is enlarged; (2) the ratio of the small end outer diameter to the punch diameter is ≥2.5.

[0033] Preferably, the diameter of the punch is ≤320mm.

[0034] Preferably, in step C1):

[0035] Quenching temperature: 501℃, quenching temperature tolerance ±3℃;

[0036] Air insulation time: 6.5h, insulation time tolerance +30min;

[0037] Material spacing: ≥160mm;

[0038] Quenching water temperature: ≤30℃, and the temperature rise of the water after quenching is ≤5℃.

[0039] Preferably, in step C2), the aging heat treatment regime is 170±3℃ for 9 hours.

[0040] Preferably, in step C3), the annealing heat treatment regime is 200±10℃ for 7 hours.

[0041] This invention provides a manufacturing process for improving the overall performance of large, thick-walled 2A14 tapered parts, with specific steps as described above. Specifically, during forging, a method of "rotary upsetting + lubrication at one end and non-lubrication at the other" is used to transform the cylindrical billet into a frustum billet (also known as an irregularly shaped billet). A method of "punching + segmented reaming" is used to transform the frustum billet into a tapered ring billet. By reducing the amount of metal fed and decreasing the wall thickness of the forging blank, the degree of grain deformation at the 1 / 2 wall thickness is increased, thereby improving the elongation at the 1 / 2 wall thickness. A dual residual stress reduction method of "machining thinning before quenching + final stress-relief annealing" is used to reduce the residual stress level of the irregularly shaped forging, thereby reducing the risk of cracking due to uneven stress release during finished product machining. Compared with existing technologies, the forming method of this invention is simple and efficient: it can be formed by free forging only, without the need to manufacture special forming molds; it can significantly reduce the manufacturing cost of this type of conical forging: there are no mold manufacturing and procurement costs; it can improve the overall performance of large thick-walled conical forgings: the elongation at 1 / 2 wall thickness of the forging is significantly improved. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0043] Figure 1 This is a structural schematic diagram of a large-sized irregular-shaped forging;

[0044] Figure 2 A schematic diagram of a reference billet for controlling the weight of materials fed during the material preparation stage;

[0045] Figure 3 A schematic diagram of the annular template used in the segmented hole enlargement process;

[0046] Figure 4 This is a schematic diagram of the frustum-shaped forging blank in step A2) of Comparative Example 1;

[0047] Figure 5 This is a schematic diagram of the conical ring blank obtained in step A3) of Comparative Example 1;

[0048] Figure 6 This is a schematic diagram of the forging obtained after machining before quenching in step B) of Comparative Example 1.

[0049] Figure 7 This is a schematic diagram of the frustum-shaped forging blank in step A2) of Example 1;

[0050] Figure 8This is a schematic diagram of the conical ring blank obtained in step A3) of Example 1;

[0051] Figure 9 This is a schematic diagram of the forging obtained after machining before quenching in step B) of Example 1. Detailed Implementation

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0053] In this article, the technical features described in an open-ended manner include both closed technical solutions composed of the listed features and open technical solutions that include the listed features.

[0054] The term “and / or” as used herein includes any and all combinations of one or more of the related listed items.

[0055] In this document, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when a range refers to an integer, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0056] In this article, when referring to units for data ranges, if the unit is only followed by the right endpoint, it indicates that the units for the left and right endpoints are the same. For example, 5–10 mm means that the units for the left endpoint “5” and the right endpoint “10” are both mm.

[0057] This document only specifically discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.

[0058] This invention provides a manufacturing process for improving the overall performance of large, thick-walled 2A14 tapered components, comprising the following steps:

[0059] A) Forging billet preparation:

[0060] A1) Material preparation: Use round ingots for material preparation, and determine the diameter and length of the round ingots;

[0061] A2) Forging and punching: The round ingot from step A1) is upset, wherein the last upset is a rotary upset, and during the last upset process, the upper end of the cylindrical billet is lubricated with oil, while the lower end is not lubricated, thereby obtaining a frustum billet; then punching is performed to obtain a frustum billet with holes.

[0062] A3) Hole enlargement: The perforated frustum blank is enlarged in sections to obtain a conical ring blank;

[0063] B) Machining before quenching:

[0064] B1) Use a CNC lathe to machine the tapered ring blank obtained in step A) to the dimensions required by the drawing; the dimensions are based on the finished workpiece with a single-sided allowance of 5-10mm.

[0065] C) Heat treatment:

[0066] C1) Quenching heat treatment:

[0067] The forgings obtained in step B) are subjected to quenching heat treatment. The selection and control principles for various process parameters and methods are as follows:

[0068] Quenching temperature: The quenching temperature is 5-10℃ lower than the overheating temperature of the material, and the quenching temperature tolerance is ±3℃ or ±4℃.

[0069] Air holding time: The holding time is determined based on the maximum heat treatment thickness of the forging billet. The minimum holding time of 120 minutes is taken as the benchmark for wall thickness ≤38mm. For every 12.7mm increase in wall thickness, the holding time is increased by 30 minutes. Where the increase in wall thickness is less than 12.7mm, it is calculated as 12.7mm.

[0070] Material spacing: The material spacing must be greater than the maximum heat treatment thickness of the forging billet;

[0071] Quenching water temperature: The temperature difference between water before and after quenching shall not exceed 10℃, and the quenching water temperature shall be ≤30℃;

[0072] Transfer time: Control transfer time ≤ 15s;

[0073] Immersion time: Control the immersion time to at least 2 minutes for every 25 mm of the maximum heat treatment thickness of the forging blank;

[0074] Number of material frame vibrations: The forging should be raised and lowered at least 5 times in water, and should not be exposed above the water surface during the immersion time;

[0075] C2) Aging heat treatment:

[0076] The forgings obtained in step C1) are subjected to aging heat treatment, with the aging heat treatment temperature controlled at 150-180℃ and the time at 5-15h.

[0077] C3) Annealing heat treatment:

[0078] The forgings obtained in step C2) are subjected to annealing heat treatment, with the annealing heat treatment temperature controlled at 190-210℃ and the time at 6-10h.

[0079] D) Machining of parts:

[0080] Based on the part drawing, the forging blank obtained in step C) is machined to the dimensions required by the part drawing.

[0081] Regarding step A) Forging billet preparation

[0082] [Regarding step A1]: Material preparation

[0083] According to the present invention, round ingots are used for material preparation, and the diameter and length of the round ingots are determined.

[0084] In this invention, the preferred principle for selecting the ingot size is as follows: After the forging billet size is designed, the corresponding billet volume is determined. According to the principle of equal volume, the ingot volume is equal to the billet volume. If a certain ingot diameter D is selected (D can be Φ666, Φ780, or Φ800), then according to the cylinder volume formula (V = πD)... 2 The ingot height h can be obtained by taking the ratio h / 4. In this invention, the selection principle for the diameter D and length h (i.e., height) of the round ingot is: h / D ratio ≤ 3. Preferably, a small-diameter ingot is used for D, and it is preferable to use ingots already in the warehouse to ensure delivery cycle.

[0085] In this invention, the preferred principle for controlling the material feeding weight during the above-mentioned material preparation process is to determine the billet weight and then feed the material according to a feeding coefficient of 1.2 to 2.0. Preferably, the billet weight is determined based on density, for example, based on an alloy density of 2.8 g / cm³. 3 Determine the weight of the billet. Feeding according to a feeding coefficient of 1.2 to 2.0 means feeding material at 1.2 to 2.0 times the weight of the billet. Figure 2 Taking the billet with the minimum product envelope size as an example, based on an alloy density of 2.8 g / cm³... 3 The billet weight is determined to be 1333 kg. Then, according to the feeding coefficient of free forgings of 1.2 to 2.0, the suitable feeding weight for this product is 1599.6 to 2666 kg. The above method of the present invention can effectively reduce the amount of metal fed, reduce the wall thickness of the forging blank, and increase the degree of grain deformation at 1 / 2 wall thickness, thereby increasing the elongation at 1 / 2 wall thickness.

[0086] [Regarding step A2]: Forging and punching

[0087] According to the present invention, the round ingot in step A1) is upset, wherein the last upset is a rotary upset, and during the last upset process, the upper end of the cylindrical blank is lubricated with oil while the lower end is not lubricated, thereby obtaining a frustum blank; then punching is performed to obtain a frustum blank with holes.

[0088] In this invention, the round ingot (hot material) in step A1) is upset and drawn. The upset and drawing can be two upsets and one drawing, three upsets and two drawing, or four upsets and three drawing.

[0089] In this invention, the final upsetting is a rotary upsetting process. During the final upsetting process, the upper end of the cylindrical billet is lubricated with oil, while the lower end is not, thus producing a frustum billet. Specifically, when the cylindrical billet is placed on the forging table (the vertical space between the upper and lower anvils), there will be an upper end and a lower end (i.e., the part in contact with the lower anvil is the lower end, and the part in contact with the upper anvil is the upper end). After the cylindrical billet is placed on the anvil, the upper end is immediately coated with oil (to reduce the coefficient of friction at the contact point between the upper end and the upper anvil, thus promoting metal flow during upsetting), while the lower end is not coated with oil (sawdust can even be sprinkled at the contact point between the lower end and the lower anvil to increase the coefficient of friction and prevent metal flow at the contact point during upsetting). Then, the upper anvil upsets the billet a certain distance (generally 50-100mm), and the upper end is coated with oil again. At the same time, the billet is rotated 90° in the circumferential direction, and the upper anvil upsets the billet a certain distance again (as above). This cycle is repeated to obtain the frustum billet.

[0090] In this invention, after the above upsetting and drawing, punching is performed. The final product of this invention is a conical part. Therefore, during punching, one end of the center hole is the thin end (i.e., the small end / small end), and the other end is the thick end (i.e., the large end / large end). In this invention, the preferred selection principle for controlling the punch diameter (i.e., the center hole diameter) is as follows: (1) the punch diameter is smaller than the hole diameter after the small end is enlarged; (2) the ratio of the small end outer diameter to the punch diameter is ≥2.5, otherwise the blank height will collapse severely during punching. To meet the above rules at the same time, it is preferred to control the punch diameter to ≤320mm in this invention. Based on existing tooling and molds, and to ensure that the mandrel strength does not bend during enlargement, a larger diameter Φ315mm punch is preferred. After the above punching, a frustum blank with holes is obtained.

[0091] [Regarding step A3]: Enlarging the hole

[0092] According to the present invention, the perforated frustum blank obtained in step A2) is segmented and expanded to obtain a conical ring blank.

[0093] In this invention, a hydraulic press, a frame, and a mandrel of suitable specifications are used to expand the perforated frustum blank in sections, thereby obtaining a conical ring blank. During the expansion process, the expansion amount is controlled to be different at the large and small ends.

[0094] The dimensions shown are theoretical design dimensions, and actual operation may not perfectly match them. The general design dimensional tolerance is ±30mm. Because the large and small ends are enlarged in segments (small end enlargement is smaller, large end enlargement is larger), to ensure dimensional accuracy, this invention will use a thin metal plate (0.5-2mm thick) to create a large-end annular template based on the inner and outer diameter limits of the large end, and a small-end annular template based on the inner and outer diameter limits of the small end (pre-fabricated, e.g., ...). Figure 3 As shown, the inner and outer diameters of both the large and small ends are expanded using a template as the standard, ensuring that the dimensional accuracy of the inner and outer diameters meets and does not exceed the tolerance. After the above expansion process, a tapered ring blank is obtained.

[0095] Regarding step B) Machining before quenching

[0096] According to the present invention, the conical ring blank obtained in step A) is machined to the dimensions required by the drawing using a CNC lathe; the dimensions are based on the finished workpiece with a single-sided allowance of 5 to 10 mm.

[0097] In this invention, it is preferable to process the conical ring blank obtained in step A) after it has cooled to room temperature. In machining, according to the drawings, a CNC lathe is used to machine the conical ring blank to the dimensions required by the drawings. These dimensions are achieved by allowing a 5-10mm allowance on each side of the finished workpiece. That is, this invention uses free forging combined with a large machining allowance, which eliminates the cost of mold manufacturing while achieving the same technical effect as die forging (even with a smaller wall thickness than die-forged blanks). It has advantages such as easy forging through at half the wall thickness, easy quenching, and low residual stress during quenching.

[0098] Regarding step C) Heat treatment

[0099] [Regarding step C1]: Quenching heat treatment.

[0100] According to the present invention, the forging obtained in step B) is subjected to quenching heat treatment. The selection and control principles for various process parameters and methods are as follows:

[0101] Quenching temperature: The quenching temperature is 5-10°C lower than the material's overheating temperature, and the quenching temperature tolerance is ±3°C or ±4°C. The temperature tolerance depends on the heat treatment furnace grade (generally, a first-class heat treatment furnace has a tolerance of ±3°C). In one embodiment of the invention, the material is 2A14, the overheating temperature is 508°C (which can be obtained by differential scanning calorimetry analysis), the quenching temperature is set at 501°C, the heat treatment furnace is a first-class furnace, and the tolerance is ±3°C.

[0102] Air holding time: The holding time is determined based on the maximum heat treatment thickness of the forging billet. A minimum holding time of 120 minutes is used as the baseline for a wall thickness ≤38mm. For every 12.7mm increase in wall thickness (less than 12.7mm is calculated as 12.7mm), the holding time increases by 30 minutes. In one embodiment of the invention, the maximum heat treatment thickness is 150mm, the minimum holding time is 390 minutes, the quenching holding time is selected as 6.5 hours, and the holding time tolerance is +30 minutes.

[0103] Spacing between billets: The spacing between billets must be greater than the maximum heat treatment thickness of the forging billet. For example, if the maximum heat treatment thickness is about 155mm, the spacing between billets can be ≥160mm, and it must be ensured that the space in which the billet is located is within the effective range of the furnace.

[0104] Quenching water temperature: The temperature difference between water before and after quenching should not exceed 10℃; preferably, to ensure good performance uniformity, the temperature difference should not exceed 5℃. To ensure good performance at 1 / 2 wall thickness, a quenching water temperature ≤30℃ should be selected.

[0105] Transfer time: The transfer time refers to the time from the opening of the furnace door to the final corner of the forging being immersed in water. To ensure good supersaturated solid solubility in the forging after quenching, the transfer time is controlled to be ≤15s in this invention.

[0106] Immersion time: The immersion time should be controlled at least 2 minutes for every 25 mm of the maximum heat treatment thickness of the forging blank. To ensure that the forging blank is fully cooled, the immersion time is preferably controlled at 20 to 30 minutes in this embodiment of the invention.

[0107] Number of material frame vibrations: The forging should be raised and lowered at least 5 times in water and should not emerge from the water surface during the immersion time. To prevent air bubbles from adhering to the surface of the forging, this invention preferably controls the number of material frame vibrations to ≥10 times.

[0108] In addition to the parameters and methods mentioned above, the present invention also prefers a placement method. In the prior art, the smallest side is generally immersed in water first. In order to ensure uniform cooling and allow water to flow through as quickly as possible, the present invention selects a placement method with the larger end facing down.

[0109] [Regarding step C2]: Aging heat treatment

[0110] According to the present invention, the forging obtained in step C1) is subjected to aging heat treatment.

[0111] In this invention, the aging heat treatment temperature is controlled to be 150–180℃, specifically 150℃, 151℃, 152℃, 153℃, 154℃, 155℃, 156℃, 157℃, 158℃, 159℃, 160℃, 161℃, 162℃, 163℃, 164℃, 165℃, 166℃, 167℃, 168℃, 169℃, 170℃, 171℃, 172℃, 173℃, 174℃, 175℃, 176℃, 177℃, 178℃, 179℃, and 180℃. The aging heat treatment time is 5–15 hours, specifically 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, and 15 hours. In one embodiment of the present invention, the aging heat treatment regime is controlled at 170±3℃ for 9 hours. After the aging heat treatment is completed, the forging is removed from the furnace and air-cooled to room temperature.

[0112] [Regarding step C3]: Annealing heat treatment

[0113] According to the present invention, the forging obtained in step C2) is subjected to annealing heat treatment.

[0114] In this invention, after step C2), the forging is placed in a heat treatment furnace for high-temperature annealing heat treatment. The annealing heat treatment temperature is controlled to be 190–210°C, specifically 190°C, 191°C, 192°C, 193°C, 194°C, 195°C, 196°C, 197°C, 198°C, 199°C, 200°C, 201°C, 202°C, 203°C, 204°C, 205°C, 206°C, 207°C, 208°C, 209°C, or 210°C. The holding time for the annealing heat treatment is 6–10 hours, specifically 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours. After the above annealing heat treatment, the forging is removed from the furnace and air-cooled. In one embodiment of this invention, the annealing heat treatment regime is controlled to be 200±10°C for 7 hours. After the aging heat treatment is completed, the forging is removed from the furnace and air-cooled to room temperature.

[0115] Regarding step D) Machining of parts

[0116] According to the present invention, the forging blank obtained in step C) is machined into the dimensions required by the part drawing according to the part drawing.

[0117] This invention provides a manufacturing process for improving the overall performance of large, thick-walled 2A14 tapered parts, with specific steps as described above. Specifically, during forging, a method of "rotary upsetting + lubrication at one end and non-lubrication at the other" is used to transform the cylindrical billet into a frustum billet (also known as an irregularly shaped billet). A method of "punching + segmented reaming" is used to transform the frustum billet into a tapered ring billet. By reducing the amount of metal fed and decreasing the wall thickness of the forging blank, the degree of grain deformation at the 1 / 2 wall thickness is increased, thereby improving the elongation at the 1 / 2 wall thickness. A dual residual stress reduction method of "machining thinning before quenching + final stress-relief annealing" is used to reduce the residual stress level of the irregularly shaped forging, thereby reducing the risk of cracking due to uneven stress release during finished product machining. Compared with existing technologies, the forming method of this invention is simple and efficient: it can be formed by free forging only, without the need to manufacture special forming molds; it can significantly reduce the manufacturing cost of this type of conical forging: there are no mold manufacturing and procurement costs; it can improve the overall performance of large thick-walled conical forgings: the elongation at 1 / 2 wall thickness of the forging is significantly improved.

[0118] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0119] Comparative Example 1

[0120] A) Forging and billet preparation:

[0121] A1) Material preparation: 2A14 aluminum alloy ingot, with dimensions of Φ800×2400mm and a weight of approximately 3376kg.

[0122] A2) Forging and punching:

[0123] The billet from step A1), heated to 450±10℃, is subjected to three upsetting and three drawing processes on a 100MN hydraulic press. It is then further upset to a height of 1300mm using a step-by-step rotary upsetting process (the upper surface of the billet is lubricated with oil, while the lower surface is not), resulting in a product as shown. Figure 4 The billet is shown as a frustum-shaped forging. After flipping the billet over, a reverse extrusion rod and a Φ365 working strip are used to punch the center hole of the billet to a thickness of 30mm for the connecting layer. Then, a perforated sheet is placed under the billet, and the connecting layer is punched through to obtain the strip. Frustum blank with a central hole.

[0124] A3) Hole enlargement:

[0125] The billet from step A2), heated to 450±10℃, is then enlarged on a 100MN press using a Φ300 mandrel, a small frame, and a flat anvil. Figure 5 The dimensions are determined to obtain a conical ring blank.

[0126] B) Machining before quenching:

[0127] The conical ring blank obtained in step A) is machined to... Figure 6 size.

[0128] C) Heat treatment:

[0129] C1) Quenching heat treatment:

[0130] After heating the forging obtained in step B) to 501±3℃ and holding it in air for 6.5h, it is rapidly transferred and rapidly cooled. The transfer time does not exceed 15s. The quenching medium is water, the quenching water temperature does not exceed 30℃, the water temperature rise after quenching does not exceed 5℃, the loading spacing is ≥160mm, the immersion time is 20~30min, and the shaking number is ≥10 times.

[0131] C2) Aging heat treatment:

[0132] The forgings obtained in step C1) are placed in an aging furnace to complete the aging heat treatment. The aging regime is T6 (temperature 170±3℃, air holding for 9 hours, and air cooling after removal from the furnace).

[0133] C3) Annealing heat treatment:

[0134] The forgings obtained in step C2) are subjected to stress-relief annealing heat treatment. The heat treatment regime is as follows: temperature 200±10℃, air holding for 7h, and air cooling after removal from the furnace.

[0135] D) Machining of parts:

[0136] The forging blank obtained in step C) is processed into Figure 1 The dimensions of the part are shown.

[0137] Example 1

[0138] A) Forging and billet preparation:

[0139] A1) Material preparation: 2A14 aluminum alloy ingot, with dimensions of Φ780×1835mm and a weight of approximately 2484kg.

[0140] A2) Forging and punching:

[0141] The billet from step A1), heated to 450±10℃, is subjected to three upsetting and three drawing processes on a 100MN hydraulic press. It is then further upset to a height of 1280mm using a step-by-step rotary upsetting process (the upper surface of the billet is lubricated with oil, while the lower surface is not), resulting in a product as shown. Figure 7 The billet is shown as a frustum-shaped forging. After flipping the billet over, a reverse extrusion rod and a Φ315 working strip are used to punch the center hole of the billet to a thickness of 30mm for the connecting layer. Then, a perforated sheet is placed under the billet, and the connecting layer is punched through to obtain the strip. Frustum blank with a central hole.

[0142] A3) Hole enlargement:

[0143] The billet from step A2), heated to 450±10℃, is then enlarged on a 100MN press using a Φ300 mandrel, a small frame, and a flat anvil. Figure 8 The dimensions are determined to obtain a conical ring blank.

[0144] B) Machining before quenching:

[0145] The conical ring blank obtained in step A) is machined to... Figure 9 size.

[0146] C) Heat treatment:

[0147] C1) Quenching heat treatment:

[0148] After heating the forging obtained in step B) to 501±3℃ and holding it in air for 6.5h, it is rapidly transferred and rapidly cooled. The transfer time does not exceed 15s. The quenching medium is water, the quenching water temperature does not exceed 30℃, the water temperature rise after quenching does not exceed 5℃, the loading spacing is ≥160mm, the immersion time is 20~30min, and the shaking number is ≥10 times.

[0149] C2) Aging heat treatment:

[0150] The forgings obtained in step C1) are placed in an aging furnace to complete the aging heat treatment. The aging regime is T6 (temperature 170±3℃, air holding for 9 hours, and air cooling after removal from the furnace).

[0151] C3) Annealing heat treatment:

[0152] The forgings obtained in step C2) are subjected to stress-relief annealing heat treatment. The heat treatment regime is as follows: temperature 200±10℃, air holding for 7h, and air cooling after removal from the furnace.

[0153] D) Machining of parts:

[0154] The forging blank obtained in step C) is machined to form... Figure 1 The dimensions of the part are shown.

[0155] Product Testing :

[0156] The products obtained in Example 1 and Comparative Example 1 were subjected to various performance tests, and the results are shown in Table 1.

[0157] Table 1: Performance Test Results

[0158] Testing items Required value Comparative Example 1 Example 1 Circumferential tensile strength / MPa ≥420 460 480 Circumferential yield strength / MPa ≥350 380 390 Circumferential elongation / % ≥6 8.0 9.0 Axial tensile strength / MPa ≥420 440 450 Axial yield strength / MPa ≥350 370 370 Axial elongation / % ≥4.5 4.0 5.0 Radial tensile strength / MPa ≥420 430 430 Radial yield strength / MPa ≥325 350 350 Radial elongation / % ≥3 2.5 4.0 Parts finished product processing status No cracks cracking No cracks

[0159] The following conclusions can be drawn from the test results in Table 1: (1) The axial and radial elongation rates of the comparative example did not meet the required values, while all test results of the example met the required values; (2) The comparative example cracked during the machining of the finished parts, while the example did not crack.

[0160] Analysis of the reasons:

[0161] The reason for conclusion (1) is that the weight of the comparative sample is about 900 kg more than that of the example. This will result in the wall thickness (285 mm) of the conical ring blank of the comparative sample being much larger than that of the example (222 mm) after the third step of hole expansion. This indicates that when the same mold is used for hole expansion, the grain deformation of the comparative sample forging at 1 / 2 wall thickness is much less than that of the example. The insufficient grain deformation results in insufficient fragmentation of the coarse second phase in the 2A14 aluminum alloy. The coarse second phase is prone to become the crack source of fracture, thus resulting in low elongation of the comparative sample forging.

[0162] The reason for conclusion (2) is as follows: The relative relationships between the conical ring blanks obtained after quenching in step B) and the finished parts in the comparative example and the embodiment are as follows: Figure 6 and Figure 9 As shown, by Figure 6 and Figure 9 It can be seen that during the quenching heat treatment in step C1), the thickness of the comparative forging billet is much greater than that of the embodiment. Under the same quenching conditions, the greater the thickness of the forging billet, the greater the residual stress formed by quenching. During the final part thinning process in step D), the uneven stress release will cause the comparative conical ring billet to crack due to tensile stress.

[0163] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of these embodiments are merely to aid in understanding the method and core ideas of the present invention, including the best mode, and to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims. The scope of protection of this patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to those expressed in the claims, or if they include equivalent structural elements that are not substantially different from those expressed in the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A manufacturing process for improving the overall performance of large, thick-walled 2A14 tapered parts, characterized in that, Includes the following steps: A) Forging and billet preparation: A1) Material preparation: Use round ingots for material preparation, and determine the diameter and length of the round ingots; in: Control the weight of materials during the material preparation process; the principle for controlling the weight of materials is: determine the weight of the billet, and then feed the materials according to the feeding coefficient of 1.2~2.

0. The selection principle for the diameter D and length h of the round ingot is: h / D ratio ≤ 3; A2) Forging and punching: The round ingot from step A1) is upset, wherein the last upset is a rotary upset, and during the last upset process, the upper end of the cylindrical billet is lubricated with oil, while the lower end is not lubricated, thereby obtaining a frustum billet; then punching is performed to obtain a frustum billet with holes. A3) Hole enlargement: The perforated frustum blank is enlarged in sections to obtain a conical ring blank; B) Machining before quenching: The conical ring blank obtained in step A) is machined to the dimensions required by the drawing using a CNC lathe; the dimensions are based on a single-sided allowance of 5~10mm on the finished workpiece. C) Heat treatment: C1) Quenching heat treatment: The forgings obtained in step B) are subjected to quenching heat treatment. The selection and control principles for various process parameters and methods are as follows: Quenching temperature: The quenching temperature is 5~10℃ lower than the overheating temperature of the material, and the quenching temperature tolerance is ±3℃ or ±4℃. Air holding time: The holding time is determined based on the maximum heat treatment thickness of the forging billet. The minimum holding time of 120 minutes is taken as the benchmark for wall thickness ≤38mm. For every 12.7mm increase in wall thickness, the holding time is increased by 30 minutes. Where the increase in wall thickness is less than 12.7mm, it is calculated as 12.7mm. Material spacing: The material spacing must be greater than or equal to the maximum heat treatment thickness of the forging billet; Quenching water temperature: The temperature difference between water before and after quenching shall not exceed 10℃, and the quenching water temperature shall be ≤30℃; Transfer time: Control transfer time ≤ 15s; Immersion time: Control the immersion time to at least 2 minutes for every 25 mm of the maximum heat treatment thickness of the forging blank; Number of material frame vibrations: The forging should be raised and lowered at least 5 times in water, and should not be exposed above the water surface during the immersion time; C2) Aging heat treatment: The forgings obtained in step C1) are subjected to aging heat treatment, with the aging heat treatment temperature controlled at 150~180℃ and the time at 5~15h. C3) Annealing heat treatment: The forgings obtained in step C2) are subjected to annealing heat treatment, with the annealing heat treatment temperature controlled at 190~210℃ and the time at 6~10h. D) Machining of parts: Based on the part drawing, the forging blank obtained in step C) is machined to the dimensions required by the part drawing.

2. The manufacturing process according to claim 1, characterized in that, The principle for controlling the weight of the feed material is: based on the density of the alloy, which is 2.8 g / cm³. 3 Determine the weight of the billet, and then feed it according to the feeding coefficient of 1.2~2.

0.

3. The manufacturing process according to claim 1, characterized in that, In step A2), the upsetting and drawing can be two upsettings and one drawing, three upsettings and two drawing, or four upsettings and three drawing.

4. The manufacturing process according to claim 1, characterized in that, In step A2), the selection principle for the punch diameter during the punching process is as follows: (1) The punch diameter is smaller than the hole diameter after the small end is enlarged; (2) The ratio of the small end outer diameter to the punch diameter is ≥2.

5.

5. The manufacturing process according to claim 4, characterized in that, The diameter of the punch is ≤320mm.

6. The manufacturing process according to claim 1, characterized in that, In step C1): Quenching temperature: 501℃, quenching temperature tolerance ±3℃; Air insulation time: 6.5h, insulation time tolerance +30min; Material spacing: ≥160mm; Quenching water temperature: ≤30℃, and the temperature rise of the water after quenching is ≤5℃.

7. The manufacturing process according to claim 1, characterized in that, In step C2), the aging heat treatment regime is 170±3℃ for 9 hours.

8. The manufacturing process according to claim 1, characterized in that, In step C3), the annealing heat treatment regime is 200±10℃ for 7 hours.

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