阅读说明：本技术 小吨位压机成形碗型机匣环坯的方法 (Method for forming bowl-shaped casing ring blank by using small-tonnage press ) 是由 兰箭 华林 毛华杰 钱东升 邓加东 于 2021-07-29 设计创作，主要内容包括：本发明的目的是提供一种小吨位压机成形碗型机匣环坯的方法,通过计算合理分配铸锭材料在镦粗、冲孔去连皮、轧环、扩口和锻挤各工序的变形量,保证小吨位压机能满足各工序的压力需求,成形时,将铸锭材料加热保温后,即在小吨位压机上进行镦粗、冲孔去连皮得到厚壁矩形环坯,对厚壁矩形环坯整形后加热并保温后,即在轧环机上轧制得到沿轴向体积分布的薄壁近矩形环坯,利用余热胀形整园后将薄壁近矩形环坯加热并保温后,即在小吨位压机上用扩口锻挤模具进行多次扩口、分步锻挤大端台阶,得到碗型机匣环坯。本发明采用多次扩口和分步大端台阶锻挤得到精密的碗型机匣环坯,极大降低所需加工设备吨位。(The invention aims to provide a method for forming a bowl-shaped case ring blank by a small-tonnage press, which reasonably distributes the deformation of an ingot casting material in each process of upsetting, punching to remove a connecting skin, rolling a ring, expanding a mouth and forging and extruding through calculation to ensure that the small-tonnage press can meet the pressure requirement of each process. The invention adopts multiple flaring and stepped large-end step forging and extruding to obtain a precise bowl-shaped casing ring blank, thereby greatly reducing the tonnage of required processing equipment.)

1. A method for forming a bowl-shaped casing ring blank by a small-tonnage press is characterized by comprising the following steps: the method comprises the steps of S1, before forming, calculating the size of the ingot casting material according to the volume of a bowl-shaped case ring forging, distributing the deformation of each process from the ingot casting to a bowl-shaped case ring blank, and determining the size of a workpiece of each process according to the deformation of each process; s2, during forming, heating and insulating the ingot casting material, namely upsetting, punching and peeling off the continuous skin on a small-tonnage press to obtain a thick-wall rectangular ring blank, shaping the thick-wall rectangular ring blank, heating and insulating the thick-wall rectangular ring blank, namely rolling the thick-wall rectangular ring blank on a ring rolling machine to obtain a thin-wall near rectangular ring blank distributed along the axial volume, heating the thin-wall near rectangular ring blank after expanding and shaping the circle by utilizing waste heat and insulating the heat, namely performing multiple flaring and stepped forging on the thin-wall near rectangular ring blank on the small-tonnage press by using a flaring forging die to obtain a bowl-shaped case ring blank;

each process is changedThe shape distribution is that the deformation of the upsetting procedure is k₁40-80%, and the deformation of punching and peeling is k₂4-12 percent, and the rolling ratio of the ring rolling process is k₃1.6-2.2, the deformation k of each flaring in the flaring process₄Calculating the maximum tonnage of a given small-tonnage press;

the adopted flaring forging and extruding die comprises a base, a lower female die and a mandrel which are arranged on the base, an upper female die arranged on the upper side of the lower female die, a plurality of groups of punches with different sizes of outer surfaces, a ring die and an ejection mechanism for ejecting a bowl-shaped casing ring blank out of the upper female die; the mandrel extends to the centers of the upper female die and the lower female die, the central hole of the punch can be matched with the mandrel, the lower part of the punch can extend into the lower female die, the outer surface of the upper part of the maximum punch is matched with the inner surface of the upper female die, the ring die can be sleeved at the top of the maximum punch, and the lower part of the ring die is provided with a lug for forging and extruding the step-by-step steps of the large-end step of the ring piece.

2. The method for forming a bowl-shaped casing ring blank by a small tonnage press as set forth in claim 1, wherein: for the ingot casting size after blanking and upsetting of the ingot casting material,

the volume V calculation formula of the ingot casting material blanking is as follows,

V＝V₀+V_{is connected with}

Wherein, V₀Is the volume of a bowl-shaped casing ring blank, V_{Is connected with}The volume of the punched connected skin is 50-150 mm, and the diameter of the connected skin is 200-300 mm;

after the volume V of the ingot casting material blanking is determined, the ingot casting height H is obtained according to the given height-diameter ratio H₀The calculation formula is as follows,

wherein the height-diameter ratio h is 1.8-3, and the diameter D of the cast ingot subjected to blanking is obtained according to the constant volume₀The calculation formula is as follows,

ingot height H after upsetting₁The calculation formula is as follows,

H₁＝0.2～0.6H₀

then according to the unchanged volume, obtaining the diameter D of the ingot after upsetting₁。

3. The method for forming a bowl-shaped casing ring blank by a small tonnage press as set forth in claim 1, wherein: for the dimensions of a thick-walled rectangular ring blank,

diameter of punch, i.e. internal diameter d of thick-walled rectangular ring blank₂Taking 200-300mm, peeling off and shaping to obtain a thick-wall rectangular ring blank, wherein the height H of the thick-wall rectangular ring blank₂In order to realize the purpose,

H₂＝0.88～0.96H₁

wherein H₁The casting height after upsetting is constant according to the volume to obtain the outer diameter D of the thick-wall rectangular ring blank₂Inner diameter d₂Height H₂。

4. The method for forming a bowl-shaped casing ring blank by a small tonnage press as set forth in claim 1, wherein: for thin-walled near-rectangular ring blank sizes,

in order to ensure that the crystal grains of the ring blank are uniform and fine, reasonable deformation needs to be applied to the ring blank, after the thick-wall rectangular ring blank is rolled, a thin-wall nearly rectangular ring blank distributed along the axial volume is obtained, and the outer diameter D of the thin-wall nearly rectangular ring blank₃Inner diameter d₃Height, heightRolling ratioThe selection value is 1.6-2.2.

5. The method for forming a bowl-shaped casing ring blank by a small tonnage press as set forth in claim 1, wherein: the size of the bowl-shaped casing ring blank in the flaring and forging processEnd outside diameter D₅Major end inner diameter d₅Minor end outer diameter D₄＝D₃Small end inner diameter d₄＝d₃Height H₄Wherein D is₃And d₃Respectively forming the outer diameter and the inner diameter of a thin-wall approximately rectangular ring blank, and performing the following calculation steps before forming:

1) calculating the flaring times

Calculating the flaring times N according to the tonnage P of the given small-tonnage press and the size of the ring blank of the bowl-shaped casing,

wherein K is a load correction coefficient, 0.8-1.2 is taken, and sigma is the flow stress of the material at the thermal forming temperature of the casing material;

2) calculating the punch size of each pass of flaring

The size calculation formula of each pass of punch head of flaring is as follows,

wherein R is_iThe large end external radius R of the ith pass flaring punch_i-1The outer radius of the large end of the punch in the (i-1) th pass is taken when i is 1The taper of the flaring punch is taken to be 4-10 degrees;

3) checking the flaring force of each pass

The flaring force of each pass can be checked by the calculation formula,

wherein, T_iThe flaring force energy of the ith pass is T_i>P, decrease R_iNumerical values, then repeat step 3) until all T_i<P(i＝1，…，N)；

4) Flaring die optimization

After checking that the flaring force meets the requirement, carrying out numerical simulation on the flaring process according to the calculated punch size, and carrying out die optimization by combining the numerical simulation result;

5) calculating the stepped forging and extruding times of the step of the big end

Forming a step at the large end of the ring blank after flaring, carrying out multiple step-by-step forging and extrusion under the condition of the tonnage limitation of a given small-tonnage press, wherein the step-by-step forging and extrusion times M are,

。

6. the method for forming a bowl-shaped casing ring blank by a small tonnage press as set forth in claim 1, wherein: the ejection mechanism comprises a long rod, an ejector block and a pry bar, the long rod is in sliding fit in a vertical through hole of the lower die, the ejector block is in sliding fit in a vertical groove of the base, the pry bar can stretch into the base to pry the ejector block, when the pry bar is not operated, the upper portion of the ejector block is supported on the base, and the top end of the long rod is flushed with the top surface of the lower concave die and is just opposite to the lower end surface of a workpiece, and the bottom end of the long rod is supported on the upper portion of the ejector block.

7. The method for forming a bowl-shaped casing ring blank by a small tonnage press as set forth in claim 1, wherein: when the flaring forging and extruding process is carried out, firstly, a thin-wall approximately rectangular ring blank distributed along the axial volume is placed on a lower female die and is in a contact state with an upper female die, then a punch is hung on the ring blank and is positioned through the matching of a central hole and a mandrel, a small-tonnage press presses the punch to perform flaring, the punches with gradually increased outer surface sizes are sequentially replaced to realize multiple flaring, after the flaring of the maximum punch is completed, a ring die is sleeved on the top of the maximum punch, then the small-tonnage press presses the ring die downwards and forges and extrudes a part of step through the large end of a ring piece by a bump, then the ring die is rotated to adjust the angle of the bump and carries out forging and extruding again until the whole ring step is forged and extruded at the large end of the ring piece step by step, finally, the ring die and the punch are taken out, and the ring blank of the bowl-shaped case is ejected out of the upper female die through an ejection mechanism.

8. The method for forming a bowl-shaped casing ring blank by a small tonnage press as set forth in claim 1, wherein: the two lugs are arranged at an interval of 180 degrees, each lug occupies 1/2M of the circumference, M is the forging and extruding times in steps, and each forging and extruding time is 360 degrees/M.

Technical Field

The invention relates to a method for forming and manufacturing a bowl-shaped casing ring blank of an aeroengine, in particular to a method for forming a bowl-shaped casing ring blank by a small-tonnage press.

Background

The engine is the heart of the airplane, and the casing, which is one of the important parts of the engine, is the base of the whole engine and is the main bearing part on the engine. Due to the fact that the bowl-shaped casing ring blank is large in size, the deformation resistance of the high-temperature alloy titanium alloy of the casing material is large, and the thickness of the ring piece is changed due to the change of the axial height of the ring blank in the flaring process, the force capacity in the ring blank forming process is further increased, and the forming precision is influenced.

At present, a large-scale press machine with more than ten thousand tons is needed for forming a bowl-shaped casing ring blank at one time, while the middle-scale press machine with the largest existing quantity is generally less than 10000 tons of force energy, and the part of production resource needs to be coiled; moreover, even if a large-scale press machine with more than ten thousand tons is used for forming, due to the reasons that the working table of the press machine is large, the force control response is slow, the centering difficulty of a tool and a die is high and the like, the precision control of the bowl-shaped casing ring blank formed on the large-scale press machine is difficult, the condition of uneven wall thickness often occurs, and the final finish rolling process is influenced.

From the above, the present situation is that the bowl-shaped casing ring blank has large forming force, cannot be formed by a small-tonnage press, and has low forming precision when a large-scale press with more than ten thousand tons is used for forming.

Disclosure of Invention

The invention aims to provide a method for forming a bowl-shaped casing ring blank by a small-tonnage press.

The technical scheme adopted by the invention is as follows:

a method for forming a bowl-shaped case ring blank by a small-tonnage press is characterized in that the deformation of ingot casting materials in each process of upsetting, punching to remove a connecting skin, rolling a ring, flaring and forging extrusion is reasonably distributed by calculating, so that the small-tonnage press can meet the pressure requirement of each process, and comprises the following steps: s1, before forming, calculating the size of a cast ingot material according to the volume of the bowl-shaped case ring forging, distributing deformation of each process from the cast ingot to a bowl-shaped case ring blank, and determining the size of a workpiece in each process according to the deformation of each process; s2, during forming, heating and insulating the ingot casting material, namely upsetting, punching and peeling off the continuous skin on a small-tonnage press to obtain a thick-wall rectangular ring blank, shaping the thick-wall rectangular ring blank, heating and insulating the thick-wall rectangular ring blank, namely rolling the thick-wall rectangular ring blank on a ring rolling machine to obtain a thin-wall near rectangular ring blank distributed along the axial volume, heating the thin-wall near rectangular ring blank after expanding and shaping the circle by utilizing waste heat and insulating the heat, namely performing multiple flaring and stepped forging on the thin-wall near rectangular ring blank on the small-tonnage press by using a flaring forging die to obtain a bowl-shaped case ring blank;

the deformation of each procedure is distributed as follows: the deformation of the upsetting step is k₁40-80%, and the deformation of punching and peeling is k₂4-12 percent, and the rolling ratio of the ring rolling process is k₃1.6-2.2, the deformation k of each flaring in the flaring process₄Calculating the maximum tonnage of a given small-tonnage press;

the adopted flaring forging and extruding die comprises a base, a lower female die and a mandrel which are arranged on the base, an upper female die arranged on the upper side of the lower female die, a plurality of groups of punches with different sizes of outer surfaces, a ring die and an ejection mechanism for ejecting a bowl-shaped casing ring blank out of the upper female die; the mandrel extends to the centers of the upper female die and the lower female die, the central hole of the punch can be matched with the mandrel, the lower part of the punch can extend into the lower female die, the outer surface of the upper part of the maximum punch is matched with the inner surface of the upper female die, the ring die can be sleeved at the top of the maximum punch, and the lower part of the ring die is provided with a lug for forging and extruding the step-by-step steps of the large-end step of the ring piece.

Blanking and upsetting ingot casting materials, and then casting ingot sizes:

the volume V calculation formula of the ingot casting material blanking is as follows,

V＝V₀+V_{is connected with}

Wherein, V₀Is the volume of a bowl-shaped casing ring blank, V_{Is connected with}The volume of the punched connected skin is 50-150 mm, and the diameter of the connected skin is 200-300 mm;

after the volume V of the cast ingot material blanking is determined, according to the given height-diameter ratioH, obtaining the ingot casting height H₀The calculation formula is as follows,

wherein the height-diameter ratio h is 1.8-3, and the diameter D of the cast ingot subjected to blanking is obtained according to the constant volume₀The calculation formula is as follows,

ingot height H after upsetting₁The calculation formula is as follows,

H₁＝0.2～0.6H₀

then according to the unchanged volume, obtaining the diameter D of the ingot after upsetting₁。

For thick-walled rectangular ring blank dimensions:

diameter of punch, i.e. internal diameter d of thick-walled rectangular ring blank₂Taking 200-300mm, peeling off and shaping to obtain a thick-wall rectangular ring blank, wherein the height H of the thick-wall rectangular ring blank₂In order to realize the purpose,

H₂＝0.88～0.96H₁

wherein H₁The casting height after upsetting is constant according to the volume to obtain the outer diameter D of the thick-wall rectangular ring blank₂Inner diameter d₂Height H₂。

For thin-walled near-rectangular ring blank size:

in order to ensure that the crystal grains of the ring blank are uniform and fine, reasonable deformation needs to be applied to the ring blank, after the thick-wall rectangular ring blank is rolled, a thin-wall nearly rectangular ring blank distributed along the axial volume is obtained, and the outer diameter D of the thin-wall nearly rectangular ring blank₃Inner diameter d₃Height, heightRolling ratioThe selection value is 1.6-2.2.

In the flaring and forging processes, the outer diameter D of the large end of the bowl-shaped casing ring blank₅Major end inner diameter d₅Minor end outer diameter D₄＝D₃Small end inner diameter d₄＝d₃Height H₄Wherein D is₃And d₃Respectively forming the outer diameter and the inner diameter of a thin-wall approximately rectangular ring blank, and performing the following calculation steps before forming:

1) calculating the flaring times

Calculating the flaring times N according to the tonnage P of the given small-tonnage press and the size of the ring blank of the bowl-shaped casing,

wherein K is a load correction coefficient, 0.8-1.2 is taken, and sigma is the flow stress of the material at the thermal forming temperature of the casing material;

2) calculating the punch size of each pass of flaring

The size calculation formula of each pass of punch head of flaring is as follows,

wherein R is_iThe large end external radius R of the ith pass flaring punch_i-1The outer radius of the large end of the punch in the (i-1) th pass is taken when i is 1The taper of the flaring punch is taken to be 4-10 degrees;

3) checking the flaring force of each pass

The flaring force of each pass can be checked by the calculation formula,

wherein, T_iThe flaring force energy of the ith pass is T_i> P, decrease R_iA value of thenRepeating the step 3) until all T_i＜P (i＝1，...，N)；

4) Flaring die optimization

After checking that the flaring force meets the requirement, carrying out numerical simulation on the flaring process according to the calculated punch size, and carrying out die optimization by combining the numerical simulation result;

5) calculating the stepped forging and extruding times of the step of the big end

Forming a step at the large end of the ring blank after flaring, carrying out multiple step-by-step forging and extrusion under the condition of the tonnage limitation of a given small-tonnage press, wherein the step-by-step forging and extrusion times M are,

。

the ejection mechanism comprises a long rod, an ejector block and a pry bar, the long rod is in sliding fit in a vertical through hole of the lower die, the ejector block is in sliding fit in a vertical groove of the base, the pry bar can stretch into the base to pry the ejector block, when the pry bar is not operated, the upper portion of the ejector block is supported on the base, and the top end of the long rod is flushed with the top surface of the lower concave die and is just opposite to the lower end surface of a workpiece, and the bottom end of the long rod is supported on the upper portion of the ejector block. The ejection mechanism can easily eject the workpiece by utilizing the lever principle, and normally, flaring and forging extrusion are not influenced.

When the flaring forging and extruding process is carried out, firstly, a thin-wall approximately rectangular ring blank distributed along the axial volume is placed on a lower female die and is in a contact state with an upper female die, then a punch is hung on the ring blank and is positioned through the matching of a central hole and a mandrel, a small-tonnage press presses the punch to perform flaring, the punches with gradually increased outer surface sizes are sequentially replaced to realize multiple flaring, after the flaring of the maximum punch is completed, a ring die is sleeved on the top of the maximum punch, then the small-tonnage press presses the ring die downwards and forges and extrudes a part of step through the large end of a ring piece by a bump, then the ring die is rotated to adjust the angle of the bump and carries out forging and extruding again until the whole ring step is forged and extruded at the large end of the ring piece step by step, finally, the ring die and the punch are taken out, and the ring blank of the bowl-shaped case is ejected out of the upper female die through an ejection mechanism.

The two lugs are arranged at an interval of 180 degrees, each lug occupies 1/2M of the circumference, M is the forging and extruding times in steps, and each forging and extruding time is 360 degrees/M. The arrangement can ensure stable stress during forging and extrusion.

The invention has the beneficial effects that:

in the blank making process, the deformation of each forming procedure is reasonably distributed through a series of calculations, the required forming force is adjusted according to the capacity of the existing equipment, the capacity of the equipment is fully exerted, multiple flaring and step-by-step large-end step forging and extrusion are adopted, and finally, the precise bowl-shaped casing ring blank is obtained, so that the high dimensional precision can be achieved, the crystal grains and the microstructure are uniform, and the tonnage of the required processing equipment is greatly reduced.

The die can be used for quickly feeding and quickly discharging, the punch and the central hole are guaranteed to be quickly and accurately centered and do not deflect, multiple flaring is achieved by sequentially replacing the punch with gradually increased outer surface size, stepped forging and extrusion are achieved by adjusting the angle of the convex block through the rotary ring die, and required pressure for flaring and step forging and extrusion is greatly reduced.

Drawings

FIG. 1 is a cross-sectional view of a ring blank of a bowl-shaped casing.

FIG. 2 is a schematic view of the overall process in the example of the present invention.

FIG. 3 is a cross-sectional view of a thin-walled, nearly rectangular ring blank distributed along the axial volume in an embodiment of the present invention.

Fig. 4 is a schematic view of each punch of the flaring process in the embodiment of the present invention.

FIG. 5 is an assembly view of a flare forging die in an embodiment of the present invention.

In the figure: 1-ring die, 2-punch, 3-bowl-shaped case ring blank, 4-upper concave die, 5-mandrel, 6-lower concave die, 7-thin-wall approximately rectangular ring blank, 8-long rod, 9-top block and 10-pry bar.

Detailed Description

The invention is further described below with reference to the drawings and the examples.

Referring to FIG. 1, in the embodiment, the target product GH4169 high-temperature alloy aeroengine bowl-shaped casing ring blank and the size thereof are shown, wherein D₅＝1150mm，d₅＝1002mm，D₄＝901mm，d₄＝770mm，H₄504 mm. High temperature alloy of this sizeThe bowl-shaped casing is formed from a cylindrical ring piece with a rectangular cross section to a bowl-shaped casing ring blank 3 at one time by using a press machine with the weight of more than 20000 tons, the most critical step in the invention is the design and optimization of a flaring process, the invention aims to solve the problems of insufficient forming precision and large forming force of the bowl-shaped casing ring blank 3, the high-precision forming of the bowl-shaped casing ring blank 3 is realized by reasonably distributing the deformation of each process, the requirement on the tonnage of forming equipment is remarkably reduced, and only a 3000-ton press machine is needed.

Therefore, the method for forming the bowl-shaped case ring blank by the small-tonnage press is provided, the deformation of the ingot casting material in each process of upsetting, punching to remove a connecting skin, rolling a ring, expanding a mouth and forging and extruding is reasonably distributed through calculation, and the small-tonnage press is ensured to meet the pressure requirement of each process, and comprises the following steps: s1, before forming, calculating the size of a cast ingot material according to the volume of the bowl-shaped case ring forging, distributing deformation of each process from the cast ingot to the bowl-shaped case ring blank 3, and determining the size of a workpiece in each process according to the deformation of each process; s2, during forming, heating the ingot casting material to a solid solution temperature, keeping the temperature, discharging the ingot casting material out of the furnace, namely, upsetting, punching and peeling off a continuous sheet on a small-tonnage press to obtain a thick-wall rectangular ring blank, reshaping the thick-wall rectangular ring blank, then returning the ingot casting material to the furnace, keeping the temperature, discharging the ingot casting material out of the furnace, namely, rolling the thick-wall rectangular ring blank on a ring rolling machine to obtain a thin-wall approximately rectangular ring blank 7 distributed along the axial volume, performing bulging and rounding by utilizing waste heat, returning the thin-wall approximately rectangular ring blank 7 to the furnace, keeping the temperature, discharging the thin-wall approximately rectangular ring blank, namely, performing multiple flaring and forging extrusion on the thin-wall approximately rectangular ring blank 7 on the small-tonnage press by using a flaring and forging die, and performing forging extrusion on steps to obtain the bowl-shaped case ring blank 3.

In the blank making process, the deformation of each forming procedure is reasonably distributed through a series of calculations, the required forming force is adjusted according to the capacity of the existing equipment, the capacity of the equipment is fully exerted, multiple flaring and step-by-step large-end step forging and extrusion are adopted, and finally the precise bowl-shaped casing ring blank 3 is obtained, so that the high dimensional precision can be achieved, the crystal grains and the microstructure are uniform, and the tonnage of the required processing equipment is greatly reduced.

The specific implementation steps are as follows:

1) and (4) calculating the deformation distribution of each process step.

To ensure sufficient deformation of the ring blank, eachThe deformation of the process steps is distributed as follows, and the deformation of the upsetting process is measured by k₁40% -80%, and measuring the punching deformation amount k₂4% -12%, and the rolling ratio is k₃1.6-2.2, the deformation k of each step required by flaring forging extrusion₄And calculating according to the maximum tonnage of the given press. The ingot size was phi 354 × 1000 mm.

2) Selective calculation of upset

And in the upsetting procedure, the deformation amount is 42%, and after upsetting is finished, the bar stock is deformed into a drum-shaped blank with the height of 580 mm.

3) Selection calculation of punched hole

Punching after upsetting is finished, taking the diameter of a punch as 260mm, taking the thickness of a connected skin as 100mm, then properly shaping, deforming the blank into a ring blank with the connected skin with phi 535x260x540mm, then punching, shaping and drawing out, H₂＝585mm， D₂＝535mm，d₂＝270mm。

4) And selecting and calculating the rolling ring.

Calculating to obtain thin-wall approximately rectangular ring blank with phi 901x770x585mm, H₃540mm, k 2.1. As shown in fig. 3.

5) And selecting and calculating flaring upsetting.

A. Flaring number calculation

A press with the tonnage of given equipment of 3000T is provided, and according to the formula:

wherein P is 3000KN, K is 1, d₅Is 1002mm, d₄At 770mm, σ is 400 MPa.

B. Design of punch for each pass of flaring

The punch size of each pass of flaring can be designed as follows,

wherein R is_iThe outer radius of the ith-pass forging punch is shown, N is the forging frequency, R_i-1The outer radius of the punch in the (i-1) th pass (the inner radius of the small end of the ring forging is taken when the (i) th pass is 1). Substitution into R₀Calculating R after 385₁＝410mm，R₂＝440mm， R₃＝465mm，R₄＝490mm，R₅＝501mm。

C. Checking flaring force energy of each pass

According to the formula, the method comprises the following steps of,

wherein Ti is the ith pass flaring force which is smaller than the tonnage P of the press, K is a load correction coefficient and can be 0.8-1.2, and is 1. The forging force in each pass is calculated as follows, T₁＝2496T，T₂＝3202T，T₃＝2841T，T₄＝2998T，T₅＝1369T。

According to the checking result, the forging and extruding force of the second pass is slightly larger than the tonnage of the equipment, and the force of the fifth pass is far smaller than the tonnage of the equipment. Therefore, further optimization of the forging process is needed, and the punch is shown in figure 4.

D. Flaring size optimization and die design

After the forging and extruding force is checked, numerical simulation is carried out according to a calculation result, and the forging and extruding process is optimized by combining a numerical simulation result, so that the forming process of the ring forging piece can be completed under the given equipment condition. The optimized dimension of each flaring punch is R₁＝410mm，R₂＝435mm，R₃＝460mm，R₄＝485mm，R₅＝501mm。

E. Calculation of stepped forging and extruding times of large-end step

After flaring, a step is required to be formed on the large end of the ring blank, multiple step-by-step forging and extrusion are carried out under the condition that the tonnage of a press is limited, the forging and extrusion times are as follows,

6) structural design of flaring forging and extruding die

The die designed according to the optimized flaring punch size and the ring forging size is shown in figure 5. In order to facilitate processing and installation, the female die part is divided into an upper female die 4 and a lower female die 6, the punch is replaced for multiple times in the flaring process, in order to facilitate punch positioning, a 1.5m mandrel 5 is used for positioning the punch, the mandrel 5 is wedged in the lower die plate through a conical surface, and all parts of the die are linked in a fastening and linking mode of screws and pins. The ring die with 1/4 lugs has two symmetrically distributed steps in the circumference, and each step occupies 45 deg of the circumference.

As shown in fig. 5, the flaring forging and extruding die comprises a base, a lower female die 6 and a mandrel 5 which are arranged on the base, an upper female die 4 which is arranged on the upper side of the lower female die 6, a plurality of groups of punches 2 with different sizes and outer surfaces, a ring die 1 and an ejection mechanism for ejecting a bowl-shaped casing ring blank 3 out of the upper female die 4; the mandrel 5 extends to the centers of the upper female die 4 and the lower female die 6, the central hole of the punch 2 can be matched with the mandrel 5, the lower part of the punch 2 can extend into the lower female die 6, the outer surface of the upper part of the maximum punch 2 is matched with the inner surface of the upper female die 4, the ring die 1 can be sleeved on the top of the maximum punch 2, and the lower part of the ring die is provided with a convex block for forging and extruding the step of the large end of the ring piece step by step. The die can be used for quickly feeding and quickly discharging, the punch 2 and the central hole ensure quick and accurate centering and do not generate deflection, multiple flaring is realized by sequentially replacing the punch 2 with gradually increased outer surface size, stepped forging and extrusion are realized by adjusting the angle of the convex block through the rotary ring die 1, and the required pressure of flaring and step forging and extrusion is greatly reduced.

Ejecting mechanism includes stock 8, kicking block 9 and pinch bar 10, stock 8 sliding fit is in the vertical through hole of die 6 down, kicking block 9 sliding fit is in the vertical inslot of base, pinch bar 10 can stretch into the base and pry up kicking block 9, when not operating the pinch bar, 9 upper portions of kicking block support on the base, stock 8's top and 6 top surfaces of lower die flush and just to terminal surface under the work piece, the bottom supports on 9 upper portions of kicking block, ejecting mechanism utilizes lever principle can be easily ejecting 3 with the work piece, and do not influence flaring and forge at ordinary times and crowd.

7) Flaring forging process

When the flaring forging and extruding process is carried out, firstly, a thin-wall approximately rectangular ring blank 7 distributed along the axial volume is placed on a lower female die 6 and is in a contact state with an upper female die 4, then a punch 2 is hung on the ring blank 7 and is positioned through the matching of a central hole and a mandrel 5, the punch 2 is pressed down by a small-tonnage press for flaring, the punch 2 with gradually increased outer surface size is replaced in sequence to realize multiple flaring, after the flaring of the maximum punch 2 is completed, a ring die 1 is sleeved on the top of the maximum punch 2, then the ring die 1 is pressed down by the small-tonnage press and a part of step is formed through the large end of a lug forging and extruding ring piece, then the ring die 1 is rotated to adjust the angle of the lug and then forging and extruding is carried out until the whole ring step is forged and extruded at the large end of the ring piece step by step, finally, the ring die 1 and the punch 2 are taken out, and the bowl-shaped case ring blank 3 is ejected out of the upper female die 4 through an ejection mechanism. The two lugs are arranged at an interval of 180 degrees, each lug occupies 45 degrees of the circumference, and the lugs rotate by 90 degrees once being forged and extruded.

It will be understood that modifications and variations can be made by persons skilled in the art in light of the above teachings and all such modifications and variations are intended to be included within the scope of the invention as defined in the appended claims.