Roll forming method for basin-shaped ring forgings

Abstract

The invention discloses a rolling forming method for a basin-shaped ring forging, which comprises the following steps of: by fully utilizing the material characteristics and preferably designing the size of a blank, enabling the lower half part of a rectangular ring blank to be jointly restrained by a main roller and a core roller, the wall thickness to be thinned, the outer diameter to be increased, and the free-state part of the upper half section of the ring blank to be influenced by the pulling force brought by the two-way change of the radial axis size of the lower half part of the blank; the radial size is increased and gradually approaches to the core roller under the combined action of the main roller and the flowability of the material, and the final forming is realized only by using the special special-shaped core roller and the universal straight main roller. In the forming process of the basin-shaped ring forge piece, the use of rolling tools which are difficult to machine and poor in universality such as a special-shaped main roller, a special-shaped core roller and a special special-shaped lining is reduced, and the service life of the main roller and the core roller of the ring rolling machine is prolonged. The production cost is saved, the production efficiency is improved, and on-time delivery of products is guaranteed. The rolling forming method for the basin-shaped ring forgings is mainly used for machining the basin-shaped ring forgings in aviation and aerospace.

Description

Technical Field:

[0001] The present invention relates to a rolling forming method for special-shaped ring forgings, and particularly to a rolling forming method for basin-shaped ring forgings. Background Art:

[0002] Special-shaped ring forgings refer to ring forgings with a non-rectangular cross-section and are important parts of aero-engines, usually machined from blank ring forgings provided by forging plants. In the existing technology, if it is necessary to roll and form the blank of a special-shaped ring forging, it is necessary to use a special-shaped core roll and a special-shaped main roll of a ring rolling mill in cooperation with a tapered roll to complete the processing. Or sleeves matching the final dimensions of the special-shaped ring forging are sleeved on a general main roll and a general core roll, and then the special-shaped ring forging is rolled and formed. Such a processing method requires preparing special-shaped core rolls and special-shaped main rolls in advance, or special main roll sleeves and core roll sleeves. This greatly prolongs the production cycle and causes a large amount of waste of non-general tooling.

[0003] Common basin-shaped parts of aero-engines are parts processed from large basin-shaped ring forging blanks. Existing basin-shaped ring forgings generally adopt special-shaped ring blank ring rolling forming. Since there are profiles on both the inner and outer diameters, a special-shaped core roll and a special-shaped main roll are used together to complete the rolling process. This scheme requires special-shaped core rolls and special-shaped main rolls, and the original blank of the basin-shaped ring forging for ring rolling must be made into a rough shape similar to the final forming size before the final forming. The processing of the special-shaped main roll and the special-shaped core roll is difficult and time-consuming. It is difficult to make the rough shape of the forging, and the steps are cumbersome. Moreover, the special-shaped core roll is extremely easy to deform and be scrapped during the process of processing the ring forging. The overall delivery cycle of the basin-shaped ring forging is greatly affected by the processing cycle of the special-shaped main roll and the special-shaped core roll, and the general delivery cycle is relatively long.

[0004] Chinese Patent CN 109365700A, published on February 22, 2019, discloses a combined forging and rolling forming method for complex variable cross-section forgings. Its essence is to process a C-shaped special-shaped ring forging by sleeving special sleeves on a general main roll and a general core roll and using a ring rolling mill. This method improves the possibility of precise manufacturing and reduces the manufacturing difficulty of complex cross-section special-shaped ring forgings by designing a symmetric ring forging blank. However, it is difficult to manufacture the special sleeves in the early stage, and the sleeves are extremely easy to deform during ring rolling and will be stuck on the main roll and the core roll, resulting in a large amount of scrapping of the sleeves, the main roll, and the core roll. Summary of the Invention:

[0005] The technical problem to be solved by the present invention is to provide a forming method for basin-shaped ring forgings with good forming effect, which can reduce the use of special-shaped tooling of a ring rolling mill to a certain extent. This method fully utilizes the material characteristics, preferably designs the blank size, and adopts multiple small-angle bending and pulling deformations. Only a special-shaped core roll and a general straight-bar main roll are used to produce basin-shaped ring forgings that meet the performance and size requirements.

[0006] To solve the above problems, the technical solution of the rolling forming method of the basin-shaped ring forging described in the present invention includes the following steps:

[0007] According to the final forming size requirements of the basin-shaped ring forging, a special core roll is designed and manufactured. At the same time, the size of the rolling blank is preferably designed, and the rectangular ring blank is rolled through three heating passes. Then, the manufactured special core roll is installed on the ring rolling mill, the prefabricated rectangular ring blank is placed, and the ring rolling mill is started to perform small-angle bending and pulling deformation rolling three times.

[0008] The first small-angle bending and pulling deformation rolling: The rectangular ring blank after heating and heat preservation is sleeved on the special core roll. The original rectangular blank is relatively thick, and the deformation resistance is large during rolling. The ring rolling mill is started to make the core roll feed towards the main roll, the feed rate is set to 0.3-0.5 mm / s, the main roll speed is set to 10-20 rad / min, and the conical roll applies pressure to control the overall axial dimension of the original rectangular blank unchanged. The lower half of the rectangular ring blank is jointly restricted by the main roll and the core roll, the wall thickness becomes thinner, and the outer diameter increases. The upper half is in a free state, affected by the pulling force brought by the two-way change of the radial and axial dimensions of the lower half of the blank, and the combined action of the fluidity of the material itself, the radial dimension increases and gradually approaches the core roll, forming an instantaneous angle α with the horizontal plane. When the inclination angle reaches 1 / 3 of the angle required for the finally formed basin-shaped ring forging, the core roll stops feeding, and the main roll maintains the speed for 20 s. The blank is taken off and reheated in the furnace for heat preservation.

[0009] The second small-angle bending and pulling deformation rolling: The blank after the first rolling is taken out and sleeved on the special core roll. Since it has undergone one bending and pulling deformation, the thickness of the blank decreases, and the deformation resistance decreases accordingly. The core roll feeds towards the main roll, the feed rate is adjusted to 0.5-1.0 mm / s, the main roll speed is set to 10-20 rad / min, and the conical roll applies pressure to control the overall axial dimension of the rectangular blank unchanged. The lower half of the ring blank is jointly restricted by the main roll and the core roll, the wall thickness is further thinned, and the outer diameter is further increased. The upper half is in a free state, affected by the pulling force brought by the two-way change of the radial and axial dimensions of the lower half of the blank, and the combined action of the fluidity of the material itself, the radial dimension is further increased and gradually approaches the core roll again, forming an instantaneous angle α with the horizontal plane. When the inclination angle reaches 2 / 3 of the angle required for the finally formed basin-shaped ring forging, the core roll stops feeding, and the main roll maintains the speed for 20 s. The blank is taken off and reheated in the furnace for heat preservation.

[0010] Third small-angle bending and pulling deformation rolling: Take out the billet that has completed two rolling processes and put it on a special core roll. Since it has undergone two bending and pulling deformations, the thickness of the billet is already very small, and the deformation resistance is also very small. The core roll feeds towards the main roll, and the feeding rate is adjusted to 1.0 - 1.5 mm / s, and the rotational speed of the main roll is set to 10 - 20 rad / min. The conical roll applies pressure to control the overall axial dimension of the rectangular billet without change. The lower half of the ring billet is jointly restricted by the main roll and the core roll, the wall thickness becomes thinner, and the outer diameter increases. The upper half is in a free state. Affected by the pulling force brought about by the two-way change in the radial dimension of the lower half of the billet and the combined effect of the fluidity of the material itself, the radial dimension increases again and gradually approaches the core roll again, forming an instantaneous angle α with the horizontal plane. When the inclination angle reaches the angle required for the final formed basin-shaped ring forging, the core roll stops feeding, and the main roll maintains the rotational speed for 30 s. At this time, the rolling of the billet is completed, the upper half is completely attached to the core roll, and the overall dimensions of the billet meet the requirements.

[0011] Furthermore, the billet used in the rolling forming method of the basin-shaped ring forging is GH4169.

[0012] Furthermore, the core roll of the rolling forming method of the basin-shaped ring forging is a special-shaped core roll, and the main roll is a general straight cylinder main roll.

[0013] Furthermore, the preferred dimension design of the original billet in the rolling forming method of the basin-shaped ring forging is based on the following empirical formula:

[0014] The height H0 of the original billet is calculated and determined according to the following formula:

[0015] H0 = H + L·sinα

[0016] —— Formula 1

[0017] In the formula:

[0018] H0 - - The height of the original billet, mm;

[0019] H - - The height of the lower half of the billet jointly restricted by the core roll and the main roll, mm;

[0020] L - - The length of the free part of the billet, mm;

[0021] α - - The angle between the free-state billet in the upper half and the horizontal plane;

[0022] The inner diameter D and outer diameter D1 of the original billet are calculated and determined according to the following formula:

[0023]

[0024] In the formula:

[0025] D - - The inner circle diameter of the original billet, mm;

[0026] D1——Original blank outer diameter, mm;

[0027] D2——Inner diameter of the lower half of the final forging, mm;

[0028] D3——Outer diameter of the lower half of the final forging, mm;

[0029] H0——original blank height, mm;

[0030] H——Height of the lower part of the blank constrained by the core roller and the main roller, mm;

[0031] D1=(0.5~0.7)D3

[0032] ——Formula 3

[0033] Where:

[0034] D1——Original blank outer diameter, mm;

[0035] D3——Outer diameter of the lower half of the final forging, mm;

[0036] In the above formula, H, L, α, D2, and D3 can all be obtained from the forging drawing, and all dimensions of the original billet can be calculated and determined by combining formulas 1 to 3.

[0037] Furthermore, the value range of D1 of the basin-shaped ring forging rolling forming method is (0.5-0.7)D3. A large number of experiments have shown that when D1<0.5D3, the free part of the blank cannot fit with the core roller, and the size is unqualified; when D1>0.7D3, the free part of the blank will have serious material accumulation, resulting in the final basin-shaped forging being thick at the top and thin at the bottom, and the size is unqualified.

[0038] Furthermore, in the basin-shaped ring forging rolling forming method, the applicable range of the angle α between the upper half of the free-state blank and the horizontal plane is 60 to 90°.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] By making full use of the material properties and preferably designing the blank size, the lower half of the rectangular ring blank is jointly restricted by the main roll and the core roll, the wall thickness becomes thinner, and the outer diameter increases. The free part of the upper half of the ring blank is affected by the pulling force brought about by the two-way change of the radial dimension of the lower half of the blank and the fluidity of the material itself. The radial dimension increases and gradually approaches the core roll, and finally forms. This method only uses a special-shaped core roll and a general-purpose straight barrel main roll to produce a basin-shaped ring forging that meets the performance and dimensional requirements. During the forming process of the basin-shaped ring forging, the use of rolling tooling such as special-shaped main rolls, special-shaped core rolls, and special-shaped bushings that are difficult to process, easy to damage, and have poor versatility is reduced, which extends the service life of the main roll and the core roll of the ring rolling machine to a certain extent. Without reducing the tissue performance of the basin-shaped ring forging and meeting the dimensional requirements. The production cost is saved, the production efficiency is improved, the production cycle is shortened, and the on-time delivery of the product is guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0042] Figure 1 is a schematic assembly diagram of the rolling forming of the basin-shaped forging described in the present invention.

[0043] Figure 2 is a schematic cross-sectional view of the rolling process of the three-time small-angle pulling and bending forming described in the present invention.

[0044] Figure 3 is a schematic cross-sectional view of the finally formed basin-shaped forging described in the present invention.

[0045] Figure 4 is a schematic cross-sectional view of the original rectangular blank described in the present invention. SPECIFIC EMBODIMENTS

[0046] To implement the rolling forming method of the basin-shaped ring forging described in the present invention, equipment such as a forging heating furnace, a press, a ring rolling machine, and a manipulator need to be provided. The following takes the superalloy with the material number GH4169 in our country as an example to describe the specific implementation of this method in detail:

[0047] The specific steps of this method are as follows:

[0048] Step 1: Rolling of the preferred size of the GH4169 alloy rectangular ring blank

[0049] The final shape requirements of the GH4169 alloy basin-shaped ring forging for an aeroengine are as Figure 4 shown. The drawing dimensions are H = 200 mm, L = 230 mm, α = 70°, D2 = 1080 mm, D3 = 1200 mm.

[0050] According to the empirical formula for the preferred size design of the original blank in the rolling forming method of the above-mentioned basin-shaped ring forging:

[0051] The height H0 of the original superalloy blank is determined by the following formula:

[0052] H0 = H + L·sinα

[0053] —— Formula 1

[0054] In the formula:

[0055] H0——The height of the original superalloy blank, mm;

[0056] H——The height of the lower half of the superalloy blank jointly restricted by the core roll and the main roll, mm;

[0057] L——The length of the free state part of the superalloy blank, mm;

[0058] α——The angle between the free state upper half of the superalloy blank and the horizontal plane;

[0059] The inner diameter D and the outer diameter D1 of the original superalloy blank are determined by the following formula:

[0060]

[0061] In the formula:

[0062] D——The inner diameter of the original superalloy blank, mm;

[0063] D1——The outer diameter of the original superalloy blank, mm;

[0064] D2——The inner diameter of the lower half of the final formed forging, mm;

[0065] D3——The outer diameter of the lower half of the final formed forging, mm;

[0066] H0——The height of the original superalloy blank, mm;

[0067] H——The height of the lower half of the superalloy blank jointly restricted by the core roll and the main roll, mm;

[0068] D1 = (0.5 - 0.7)D3

[0069] —— Formula 3

[0070] In the formula:

[0071] D1——The outer diameter of the original superalloy blank, mm;

[0072] D3——The outer diameter of the lower half of the final formed forging, mm;

[0073] In this embodiment, D1=0.6D3 is preferred. In the above formula, H, L, α, D2, and D3 have all been obtained from the forging drawing. All dimensions of the GH4169 alloy billet can be calculated and determined by combining formulas 1 to 3.

[0074] Calculation shows that the blank height H0 is 417 mm, the blank outer diameter D1 is 720 mm, and the blank inner diameter D is 485 mm.

[0075] Two pieces of GH4169 alloy bars are cut, heated, roughened and punched, and then pre-rolled into the following three-stage pre-rolling: Figure 4 The rectangular blank shown has the required dimensions of Ф720±5×Ф485±5×417mm.

[0076] The actual dimensions of GH4169 alloy billet are as follows:

[0077] Number Outer diameter (mm) Inner diameter (mm) Overall height (mm) Mass (kg) 1 735 490 418 184.8 2 728 488 419 182.6

[0078] Step 2: Three small angle pulling, bending, deformation and rolling

[0079] The first small angle pulling bending deformation rolling: Figure 1 As shown, the GH4169 alloy rectangular ring blank 4 that has been heated and insulated is sleeved on the special core roller 3. Because the original GH4169 alloy rectangular billet is thick, it has a large deformation resistance during rolling. The ring rolling machine is started to feed the core roller 3 toward the main roller 6, the feed rate is set to 0.3-0.5 mm / s, the speed of the main roller 6 is set to 10-20 rad / min, and the cone roller 1 and cone roller 2 apply pressure to control the overall axial size of the rectangular ring blank 4 to remain unchanged. The lower half of the rectangular ring blank 4 is constrained by the main roller 6 and the core roller 3, the wall thickness becomes thinner, and the outer diameter increases. The upper half is in a free state. Affected by the pulling force caused by the bidirectional change of the diameter and axis size of the lower half of the billet, as well as the combined effect of the fluidity of the material itself, the radial size increases and gradually approaches the core roller 3, forming an instantaneous angle α with the horizontal plane. When the inclination angle reaches 1 / 3 of the angle required for the final GH4169 alloy basin-shaped ring forging, that is, when α=83°, the core roller 3 stops feeding and the main roller 6 keeps rotating for 20 seconds. The blank is removed and returned to the furnace for heating to 1020°C±10°C for 6 hours.

[0080] Second small-angle pulling and bending deformation rolling: Take out the GH4169 alloy blank 4 completed in the first rolling and sleeve it on the special core roll 3. Since it has been rolled in one heat, the thickness of the blank decreases, and the deformation resistance decreases accordingly. The core roll 3 feeds towards the main roll 6, and the feeding rate is adjusted to 0.5 - 1.0 mm / s. The rotational speed of the main roll 6 is set to 10 - 20 rad / min. The cone rolls 1 and 2 apply pressure to control that the overall axial dimension of the GH4169 alloy rectangular blank 4 remains unchanged. The lower half of the GH4169 alloy rectangular blank 4 is jointly restricted by the main roll 6 and the core roll 3, the wall thickness further thins, and the outer diameter further increases. The upper half is in a free state. Affected by the pulling force brought by the two-way change of the radial dimension of the lower half of the blank and the combined action of the fluidity of the material itself, the radial dimension further increases and gradually approaches the core roll 3 again, forming an instantaneous angle α with the horizontal plane. When the inclination angle reaches 2 / 3 of the angle required for the finally formed GH4169 alloy basin-shaped ring forging, that is, when α = 76°, the core roll 3 stops feeding, and the main roll 6 maintains the rotational speed for 20 s. Take down the blank and heat it in the furnace to 1020 °C ± 10 °C and hold for 6 hours.

[0081] Third small-angle pulling and bending deformation rolling: Take out the GH4169 alloy blank 4 completed in two rollings and sleeve it on the special core roll 3. Since it has been rolled in two heats, the thickness of the GH4169 alloy blank is already very small, and the deformation resistance is also very small. The core roll 3 moves towards the main roll 6, and the feeding rate is adjusted to 1.0 - 1.5 mm / s. The rotational speed of the main roll 6 is set to 10 - 20 rad / min. The cone rolls 1 and 2 apply pressure to control that the overall axial dimension of the GH4169 alloy rectangular blank 4 remains unchanged. The lower half of the GH4169 alloy rectangular ring blank 4 is jointly restricted by the main roll 6 and the core roll 3, the wall thickness thins again, and the outer diameter increases again. The upper half is in a free state. Affected by the pulling force brought by the two-way change of the radial dimension of the lower half of the blank and the combined action of the fluidity of the material itself, the radial dimension increases again and gradually approaches the core roll 3 again, forming an instantaneous angle α with the horizontal plane. When the inclination angle reaches the angle required for the finally formed GH4169 alloy basin-shaped ring forging, that is, when α = 70°, the core roll 3 stops feeding, and the main roll 6 maintains the rotational speed for 30 s. At this time, the rolling of the GH4169 alloy blank is completed, and the upper half of the blank completely fits the core roll.

[0082] The whole deformation process is as Figure 2 shown, and the original GH4169 alloy rectangular blank 4 gradually fits completely with the core roll 3. Figure 2 It shows the morphology of the GH4169 alloy ring blank during three small-angle pulling and bending deformation rollings.

[0083] The specific dimensions of the completed rolled GH4169 alloy basin-shaped ring forging are as follows in the table:

[0084] Number H (mm) L (mm) α <![CDATA[D2(mm)]]> <![CDATA[D3(mm)]]> 1 203 235 69° 1078 1235 2 202 233 70° 1081 1226

[0085] After rough machining, physical and chemical tests are carried out on the GH4169 alloy basin-shaped ring forgings. The tensile strength is 976 MPa, the yield strength is 566 MPa, and the elongation is 32%. The dimensions are stable after machining, without serious deformation, and the ovality is 0.15 mm. It meets the requirements of the drawings and standards.

[0086] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for rolling and forming a basin-shaped ring forging, characterized in that, It includes the following steps: According to the requirements of the final forming dimensions of the basin-shaped ring forging, a special core roll is designed and manufactured. Meanwhile, the dimensions of the rolling blank are optimized. The manufactured special core roll is installed on the ring rolling mill, the prefabricated rectangular ring blank is placed, and the ring rolling mill is started to perform small-angle bending and pulling deformation rolling in three times. The first small-angle bending and pulling deformation rolling: The heated and heat-insulated rectangular ring blank is sleeved on the special core roll. The core roll feeds towards the main roll, and the feed rate is set to 0.3 - 0.5 mm / s. The rotational speed of the main roll is set to 10 - 20 rad / min. The conical roll applies pressure to control the overall axial dimension of the original rectangular blank unchanged. When the inclination angle of the free part of the blank reaches 1 / 3 of the angle required for the final formed basin-shaped ring forging, the core roll stops feeding, and the main roll maintains the rotational speed for 20 s. The second small-angle bending and pulling deformation rolling: The blank completed in the first rolling is taken out and sleeved on the special core roll. The core roll feeds towards the main roll, and the feed rate is adjusted to 0.5 - 1.0 mm / s. The rotational speed of the main roll is set to 10 - 20 rad / min. The conical roll applies pressure to control the overall axial dimension of the original rectangular blank unchanged. When the inclination angle of the free part of the blank reaches 2 / 3 of the angle required for the final formed basin-shaped ring forging, the core roll stops feeding, and the main roll maintains the rotational speed for 20 s. The third small-angle bending and pulling deformation rolling: The blank completed in the two rollings is taken out and sleeved on the special core roll. The core roll feeds towards the main roll, and the feed rate is adjusted to 1.0 - 1.5 mm / s. The rotational speed of the main roll is set to 10 - 20 rad / min. The conical roll applies pressure to control the overall axial dimension of the original rectangular blank unchanged. When the inclination angle of the free part of the blank reaches the angle required for the final formed basin-shaped ring forging, the core roll stops feeding, and the main roll maintains the rotational speed for 30 s. At this time, the blank has completed rolling, and the upper half of the blank completely adheres to the core roll.

2. A method for roll forming a basin-shaped ring forging according to claim 1, characterized in that, The forging material is GH4169.

3. A method for rolling and forming a basin-shaped ring forging according to claim 1, characterized in that The core roll is a special-shaped core roll, and the main roll is a general straight-barrel main roll.

4. A method for rolling and forming a basin-shaped ring forging according to claim 1, characterized in that, The optimal dimension design of the original rectangular blank is based on the following empirical formula: The height H0 of the original blank is calculated and determined according to the following formula: Formula ①: H0 = H + L·sinα In the formula: H0 - The height of the original blank, mm; H - The height of the lower half of the blank jointly restricted by the core roll and the main roll, mm; L - The length of the free part of the blank, mm; α - The included angle between the upper half of the free blank and the horizontal plane The inner diameter D and the outer diameter D1 of the original blank are calculated and determined according to the following formula: Formula ②: In the formula: D - The inner diameter of the original blank, mm; D1 - The outer diameter of the original blank, mm; D2 - The inner diameter of the lower half of the final formed forging, mm; D3 - The outer diameter of the lower half of the final formed forging, mm; H0 - The height of the original blank, mm; H - The height of the lower half of the blank jointly restricted by the core roll and the main roll, mm; Formula ③: D1 = (0.5 - 0.7)D3 In the formula: D1 - The outer diameter of the original blank, mm; D3 - The outer diameter of the lower half of the final formed forging, mm.

5. A method for roll forming a basin-shaped ring forging according to claim 4, characterized in that, The value range of the outer diameter D1 of the original blank is (0.5 to 0.7) times the outer diameter D3 of the lower half of the finally formed forging.

6. A method for rolling and forming a basin-shaped ring forging according to claim 4, characterized in that, The applicable range of the angle α between the upper half of the blank in the free state and the horizontal plane is 60 to 90°.

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