Large-wall-thickness shell forging forming method

Abstract

The invention relates to a large-wall-thickness shell forge piece forming method which comprises the following steps that a forming die blank is prefabricated according to the size, the forming die blank is a reducer pipe, the large end of the reducer pipe faces upwards, and the small end of the reducer pipe faces downwards; moulding bed forming; carrying out primary oblique breaking; carrying out secondary inclination breaking; breaking off for the third time; and pressing ring upsetting is conducted, specifically, the pressing ring presses and upsets the tire mold blank till the upper end of the tire mold blank is flush with the upper end of the first tire mold, a forged piece is obtained, the third punch is sleeved with the pressing ring, the pressing ring is a square ring, and the outer diameter of the pressing ring is larger than the inner diameter of an inner cavity of the first tire mold. According to the forming method for the large-wall-thickness shell forge piece, the purposes of material distribution and punching are achieved by prefabricating the forming die blank according to the size and making the blank through the forming die with the first heating number. And the small end of the forge piece is formed through second heating number special-shaped pre-rolling. And forming the large end of the forge piece through third-heating-number tire mold forming. According to the method, the size of the blank is controlled through the die in the whole process, the difference between the manufactured forgings is small, the size state fluctuation is small, the quality consistency of the forgings is good, the heating number is small, operation is easy, and the production efficiency of the shell forgings is improved.

Description

Technical Field

[0001] The invention relates to the technical field of forging forming, in particular to a method for forming a shell forging with a large wall thickness. Background Art

[0002] Ti-6Al-4V (TC4) alloy, due to its good comprehensive performance, forming performance and welding performance, more and more titanium alloys are used in airframes and engine casings. The strength of TC4 alloy is equivalent to that of general high-strength structural steel, but its density is only 57% of steel. The density of aluminum alloy and magnesium alloy is low, only 60% and 40% of titanium alloy, but its tensile strength is less than 1 / 3 of titanium alloy. Therefore, TC4 alloy is selected as an alternative material for fixed casings.

[0003] The forming methods of TC4 alloy shells usually include the following: free forging, die forging and die forging. Among them, in free forging, the raw material input is heavy, the product streamline is poor, the performance is low, and the cost is high. In die forging, due to the large bending angle, the rectangular billet is easy to fold during the material division process, such as Figure 1 As shown, it can be clearly seen that the inner wall of the shell has multiple raised folded edges, and the number of firings is high and the efficiency is low. The die forging type is limited by the equipment, the die forging equipment is expensive, and the power and energy consumption required by the equipment are too large.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0005] In view of the shortcomings of the prior art, the embodiment of the present invention discloses a method for forming a thick-walled shell forging to solve the problems of low production efficiency and low yield of die forging.

[0006] The technical solution adopted by the present invention is as follows:

[0007] The method for forming a thick-walled shell forging comprises the following steps: prefabricating a membrane blank according to the size, wherein the membrane blank is a reducer, wherein the large end of the reducer faces upward and the small end faces downward; forming the membrane: forging heating: heating to 30°C to 35°C below the phase transition point Tβ, and keeping the temperature for 45 to 135 minutes; primary bending: placing the membrane blank into the first membrane, and using a first punch to bend the membrane blank downward, wherein the first punch is an inverted frustum cone; secondary bending: using a second punch to bend the membrane blank downward, and wherein the second punch is an inverted frustum cone; tertiary bending: guiding The column passes through the center of the fetal membrane blank and rests against the bottom of the first fetal membrane. The third punch includes a square ring sleeved on the outside of the guide column and an inverted cone ring arranged at the lower end of the square ring. The third punch is pressed down until the upper end of the inverted cone ring is flush with the upper end of the first fetal membrane, and the fetal membrane blank is upset and divided. The guide column is a cylinder; the pressure ring upsets: the pressure ring presses down to upset the fetal membrane blank until the upper end of the fetal membrane blank is flush with the upper end of the first fetal membrane to obtain a forging. The pressure ring is sleeved on the outside of the third punch. The pressure ring is a square ring, and its outer diameter is larger than the inner diameter of the inner cavity of the first fetal membrane.

[0008] A further technical solution is that the angle between the first punch generatrix and the top surface is 70° to 75°, the angle between the second punch generatrix and the top surface is 60° to 65°, and the angle between the lower generatrix of the conical ring and the top surface is 30° to 35°.

[0009] Its further technical solution is that the steps of prefabricating the fetal membrane blank according to size include: blanking; chamfering; fetal membrane blank making: forging heating: heating to 30℃~35℃ below the phase change point Tβ, and keeping warm for 175~265min; placing the blank into the second fetal mold, and upsetting the blank until it is flush with the second fetal mold; using a fourth punch to punch, the fourth punch includes a plate body and a column connected to the lower end of the plate body, the outer diameter of the plate body is larger than the inner diameter of the second fetal membrane cavity; special-shaped rolling: forging heating: heating to 30℃~35℃ below the phase change point Tβ, and keeping warm for 70~160min; using a ring machine to roll it into a fetal membrane blank.

[0010] A further technical solution is to use TC4 forging rods for cutting and to use a vacuum consumable arc furnace for three smeltings.

[0011] A further technical solution is that after the profile rolling step, the ratio of the height of the tire membrane blank to the wall thickness of the large end is ≤2.5. According to previous production experience, the best ratio is ≤2.5. If it is greater than 2.5, there is a risk of upsetting and folding. Preferably, the ratio of the height of the tire membrane blank to the wall thickness of the large end is 0.5 to 2.5.

[0012] A further technical solution is that after the fetal membrane molding step, the method further includes the following steps: annealing: heating to 700°C to 720°C, keeping the temperature for 90 to 120 minutes, and air cooling after taking out of the furnace.

[0013] A further technical solution is that after the annealing step, it also includes the following testing steps: hardness inspection: 100% of the forgings are inspected for hardness, and the hardness requirement is HB ≥ 3.30 mm; sampling: test rings are cut from the forging body; physical and chemical testing: the test rings are subjected to physical and chemical testing according to the requirements of standard GJB 2744A-2007; rough processing: machining is performed according to the requirements of the drawings; ultrasonic flaw detection: meets the A1 level requirements in GB / T 5193-2007.

[0014] A further technical solution is that the weight percentage of each chemical element in the forging is: Al: 5.5-6.75%; V: 3.5-4.5%; Fe: ≤0.3%; C: ≤0.08%; N: ≤0.05%; H: ≤0.015%; O: ≤0.2%; other elements: single ≤0.1%, total ≤0.4%; the remainder is Ti.

[0015] The beneficial effects of the embodiments of the present invention are as follows:

[0016] (A) The method for forming thick-walled shell forgings of the embodiment of the present invention achieves the purpose of material division and punching by prefabricating the membrane blank according to the size and forming the blank in the first fire. The small end of the forging is formed by pre-rolling in the second fire. The membrane is formed in the third fire to form the large end of the forging. The method of the present invention controls the size of the blank through the mold in the whole process, and the difference between the forgings is small, the dimensional state fluctuation is small, the quality consistency of the forgings is good, and the number of fires is small, the operation is simple, and the production efficiency of shell forgings is improved.

[0017] (ii) Furthermore, after the special-shaped rolling step, when the ratio of the height of the diaphragm blank to the wall thickness of the large end is ≤2.5, the risk of folding is small, and the angle of each beveling is small. Before the third beveling, a guide pin is first used to pass through the center of the diaphragm blank and against the bottom of the first diaphragm to avoid the risk of material piling up to the small head when the third punch is pressed down for upsetting, resulting in the problem of excess meat on the inside of the small head, thereby improving the yield rate of forgings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a photo of a thick-walled shell forging made according to the prior art.

[0019] Figure 2 The present invention is a flow chart of the method for forming a thick-walled shell forging.

[0020] Figure 3 The present invention is a flow chart of the fetal membrane forming in the method for forming a thick-walled shell forging.

[0021] Figure 4 The present invention is a flow chart of the tire membrane blank making in the heavy-walled shell forging forming method of the present invention.

[0022] Figure 5 It is a schematic diagram of the structure before and after upsetting in the fetal membrane making step.

[0023] Figure 6 It is a schematic diagram of the structure before and after punching in the fetal membrane making step.

[0024] Figure 7 It is a structural schematic diagram of the special-shaped ring rolling step.

[0025] Figure 8 This is a schematic diagram of the structure before and after the membrane is bent once during the fetal membrane molding step.

[0026] Fig. 9 This is a schematic diagram of the structure before and after the second bending in the fetal membrane forming step.

[0027] Fig.10 This is a schematic diagram of the structure before and after the three bends in the fetal membrane forming steps.

[0028] Fig.11 It is a schematic diagram of the structure before and after the pressure ring is upset in the fetal membrane forming step.

[0029] Fig.12 The forgings are obtained by the method for forming thick-walled shell forgings according to the present invention.

[0030] Fig.13 This is the x200 metallographic result of the forging obtained in the first embodiment.

[0031] Fig.14 This is the x200 metallographic result of the forging obtained in the second embodiment.

[0032] Fig.15 This is a low-magnification microstructure photograph of the forging obtained in the first embodiment.

[0033] Fig.16 This is a low-magnification microstructure photograph of the forging obtained in the second embodiment.

[0034] In the figure:

[0035] 1. First fetal membrane; 2. First punch; 3. Second punch; 4. Third punch; 5. Guide pin; 6. Pressure ring; 7. Second fetal membrane; 8. Fourth punch; 9. Ring machine; 91. Outer roller; 92. Inner roller; 93. Pressure roller. DETAILED DESCRIPTION

[0036] The specific implementation of the present invention is described below in conjunction with the accompanying drawings.

[0037] In order to make the purpose, technical scheme and advantages of the present invention clearer, the device proposed by the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the accompanying drawings adopt a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, please refer to the accompanying drawings. It should be noted that the structure, proportion, size, etc. illustrated by the accompanying drawings of this specification are only used to match the content disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no technical substantive significance. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effect that the present invention can produce and the purpose that can be achieved, should still fall within the scope of the technical content disclosed by the present invention.

[0038] First embodiment:

[0039] like Figure 2 As shown, the method for forming a thick-walled shell forging comprises the following steps:

[0040] Step S1, unloading.

[0041] Specifically, TC4 forging rods are used for blanking, and a vacuum consumable arc furnace (VAR) is used for 3 times of melting. The weight percentage of each chemical element in the forging is:

[0042] Al: 5.5~6.75%; V: 3.5~4.5%; Fe: ≤0.3%; C: ≤0.08%; N: ≤0.05%; H: ≤0.015%; O: ≤0.2%; Other elements: individual ≤0.1%, total ≤0.4%; the balance is Ti.

[0043] Step S2, chamfering.

[0044] Step S3, fetal membrane blank making.

[0045] like Figure 4 , Figure 5 and Figure 6 As shown, specifically, the fetal membrane blank making comprises the following steps:

[0046] Step S31, forging heating: heating the heating furnace at full power to 32°C below the phase transition point Tβ, and keeping the temperature for 220 minutes.

[0047] Specifically, the phase transition point Tβ temperature of TC4 material is 950°C.

[0048] Step S32, placing the blank into the second mold, and upsetting the blank until it is flush with the second mold.

[0049] Step S33 , punching is performed using a fourth punch 8 , wherein the fourth punch 8 comprises a plate body and a column connected to the lower end of the plate body, and the outer diameter of the plate body is greater than the inner diameter of the inner cavity of the second fetal membrane 7 .

[0050] Step S4: profile rolling.

[0051] like Figure 7 As shown, specifically, the profile rolling includes the following steps:

[0052] Step S41, forging heating: the heating furnace is heated at full power to 32°C below the phase transition point Tβ, and kept warm for 115 minutes.

[0053] Step S42, using the ring machine 9 to roll the tire membrane blank.

[0054] Specifically, the ring machine 9 includes a rotating outer roller 91, an inner roller 92 and two pressure rollers 93. The outer roller 91 is arranged vertically, and the inner side shape is the same as the inverted reducer. The inner roller 92 is arranged vertically and is a cylinder, and together with the outer roller 91, the thickness and shape of the tire membrane blank are rolled. The two pressure rollers 93 are arranged horizontally to roll the height of the tire membrane blank. During rolling, the reducer of the tire membrane blank faces downward at the large end and upward at the small end. After the special-shaped rolling step, the ratio of the height of the tire membrane blank to the wall thickness of the large end is ≤2.5.

[0055] Step S5, fetal membrane molding.

[0056] like Figure 3 , Figure 8 , Fig. 9 , Fig.10 and Fig.11 As shown, specifically, the fetal membrane molding includes the following steps:

[0057] Step S51, forging heating: heating the heating furnace at full power to 32°C below the phase transition point Tβ, and keeping the temperature for 90 minutes.

[0058] Step S52, one-time bending: the fetal membrane blank is placed in the first fetal membrane 1, and the first punch 2 is pressed downward to bend the fetal membrane blank, and the first punch 2 is an inverted frustum cone shape.

[0059] Specifically, the included angle between the generatrix of the first punch 2 and the top surface is 72°, and the beveling angle of the large end of the fetal membrane blank is 18°.

[0060] Step S53, secondary beveling: the second punch 3 presses down to bend the fetal membrane blank, and the second punch 3 is an inverted frustum cone type.

[0061] Specifically, the included angle between the generatrix of the second punch 3 and the top surface is 63°, and the beveling angle of the large end of the fetal membrane blank is 27°.

[0062] Step S54, three times of bending: the guide post 5 passes through the center of the fetal membrane blank and rests against the bottom of the first fetal membrane 1, the third punch 4 includes a square ring sleeved on the outside of the guide post 5 and an inverted cone ring arranged at the lower end of the square ring, the third punch 4 is pressed down until the upper end of the inverted cone ring is flush with the upper end of the first fetal membrane 1, the fetal membrane blank is upset and divided, the guide post 5 is a cylinder.

[0063] Specifically, the angle between the lower generatrix of the conical ring and the top surface is 32°, and the beveling angle of the large end of the fetal membrane blank is 58°.

[0064] Step S55, upsetting the pressure ring 6: the pressure ring 6 presses down to upset the fetal membrane blank until the upper end of the fetal membrane blank is flush with the upper end of the first fetal membrane 1 to obtain a forging. The pressure ring 6 is sleeved on the outside of the third punch 4. The pressure ring 6 is a square ring, and its outer diameter is larger than the inner diameter of the inner cavity of the first fetal membrane 1.

[0065] Step S6, annealing.

[0066] Specifically, the mixture was heated to 710°C, kept at that temperature for 105 minutes, and then air-cooled.

[0067] Step S7, detection.

[0068] Specifically, the detection includes the following steps:

[0069] Step S71, hardness inspection: 100% of the forgings are inspected for hardness, and the hardness requirement is HB(d)≥3.30mm.

[0070] Step S72, sampling: cutting a test ring from the forging body.

[0071] Step S73, physical and chemical testing: the test ring is subjected to physical and chemical testing according to the requirements of standard GJB 2744A-2007;

[0072] Step S74, rough machining: perform machining according to the drawing requirements.

[0073] Step S75, ultrasonic flaw detection: in accordance with the A1 level requirements in GB / T 5193-2007.

[0074] Second embodiment:

[0075] like Figure 2 As shown, the method for forming a thick-walled shell forging comprises the following steps:

[0076] Step S1, unloading.

[0077] Specifically, TC4 forging rods are used for blanking, and a vacuum consumable arc furnace (VAR) is used for 3 times of melting. The weight percentage of each chemical element in the forging is:

[0078] Al: 5.5~6.75%; V: 3.5~4.5%; Fe: ≤0.3%; C: ≤0.08%; N: ≤0.05%; H: ≤0.015%; O: ≤0.2%; Other elements: individual ≤0.1%, total ≤0.4%; the balance is Ti.

[0079] Step S2, chamfering.

[0080] Step S3, fetal membrane blank making.

[0081] like Figure 4 , Figure 5 and Figure 6 As shown, specifically, the fetal membrane blank making comprises the following steps:

[0082] Step S31, forging heating: heating the heating furnace at full power to 30°C below the phase transition point Tβ, and keeping the temperature for 175 minutes.

[0083] Specifically, the phase transition point Tβ temperature of TC4 material is 950°C.

[0084] Step S32, placing the blank into the second mold, and upsetting the blank until it is flush with the second mold.

[0085] Step S33 , punching is performed using a fourth punch 8 , wherein the fourth punch 8 comprises a plate body and a column connected to the lower end of the plate body, and the outer diameter of the plate body is greater than the inner diameter of the inner cavity of the second fetal membrane 7 .

[0086] Step S4: profile rolling.

[0087] like Figure 7 As shown, specifically, the profile rolling includes the following steps:

[0088] Step S41, forging heating: heating the heating furnace at full power to 30°C below the phase transition point Tβ, and keeping the temperature for 70 minutes.

[0089] Step S42, using the ring machine 9 to roll the tire membrane blank.

[0090] Specifically, the ring machine 9 includes a rotating outer roller 91, an inner roller 92 and two pressure rollers 93. The outer roller 91 is arranged vertically, and the inner side shape is the same as the inverted reducer. The inner roller 92 is arranged vertically and is a cylinder, and together with the outer roller 91, the thickness and shape of the tire membrane blank are rolled. The two pressure rollers 93 are arranged horizontally to roll the height of the tire membrane blank. During rolling, the reducer of the tire membrane blank faces downward at the large end and upward at the small end. After the special-shaped rolling step, the ratio of the height of the tire membrane blank to the wall thickness of the large end is ≤2.5.

[0091] Step S5, fetal membrane molding.

[0092] like Figure 3 , Figure 8 , Fig. 9 , Fig.10 and Fig.11 As shown, specifically, the fetal membrane molding includes the following steps:

[0093] Step S51, forging heating: heating the heating furnace at full power to 30°C below the phase transition point Tβ, and keeping the temperature for 45 minutes.

[0094] Step S52, one-time bending: the fetal membrane blank is placed in the first fetal membrane 1, and the first punch 2 is pressed downward to bend the fetal membrane blank, and the first punch 2 is an inverted frustum cone shape.

[0095] Specifically, the included angle between the generatrix of the first punch 2 and the top surface is 70°, and the beveling angle of the large end of the fetal membrane blank is 20°.

[0096] Step S53, secondary beveling: the second punch 3 presses down to bend the fetal membrane blank, and the second punch 3 is an inverted frustum cone type.

[0097] Specifically, the included angle between the generatrix of the second punch 3 and the top surface is 60°, and the beveling angle of the large end of the fetal membrane blank is 30°.

[0098] Step S54, three times of bending: the guide post 5 passes through the center of the fetal membrane blank and rests against the bottom of the first fetal membrane 1, the third punch 4 includes a square ring sleeved on the outside of the guide post 5 and an inverted cone ring arranged at the lower end of the square ring, the third punch 4 is pressed down until the upper end of the inverted cone ring is flush with the upper end of the first fetal membrane 1, the fetal membrane blank is upset and divided, the guide post 5 is a cylinder.

[0099] Specifically, the angle between the lower generatrix of the conical ring and the top surface is 30°, and the beveling angle of the large end of the fetal membrane blank is 60°.

[0100] Step S55, upsetting the pressure ring 6: the pressure ring 6 presses down to upset the fetal membrane blank until the upper end of the fetal membrane blank is flush with the upper end of the first fetal membrane 1 to obtain a forging. The pressure ring 6 is sleeved on the outside of the third punch 4. The pressure ring 6 is a square ring, and its outer diameter is larger than the inner diameter of the inner cavity of the first fetal membrane 1.

[0101] Step S6, annealing.

[0102] Specifically, the mixture is heated to 720° C., kept at this temperature for 90 minutes, and then air-cooled.

[0103] Step S7, detection.

[0104] Specifically, the detection includes the following steps:

[0105] Step S71, hardness inspection: 100% of the forgings are inspected for hardness, and the hardness requirement is HB(d)≥3.30mm.

[0106] Step S72, sampling: cutting a test ring from the forging body.

[0107] Step S73, physical and chemical testing: the test ring is subjected to physical and chemical testing according to the requirements of standard GJB 2744A-2007;

[0108] Step S74, rough machining: perform machining according to the drawing requirements.

[0109] Step S75, ultrasonic flaw detection: in accordance with the A1 level requirements in GB / T 5193-2007.

[0110] Third embodiment:

[0111] like Figure 2 As shown, the method for forming a thick-walled shell forging comprises the following steps:

[0112] Step S1, unloading.

[0113] Specifically, TC4 forging rods are used for blanking, and a vacuum consumable arc furnace (VAR) is used for 3 times of melting. The weight percentage of each chemical element in the forging is:

[0114] Al: 5.5~6.75%; V: 3.5~4.5%; Fe: ≤0.3%; C: ≤0.08%; N: ≤0.05%; H: ≤0.015%; O: ≤0.2%; Other elements: individual ≤0.1%, total ≤0.4%; the balance is Ti.

[0115] Step S2, chamfering.

[0116] Step S3, fetal membrane blank making.

[0117] like Figure 4 , Figure 5 and Figure 6 As shown, specifically, the fetal membrane blank making comprises the following steps:

[0118] Step S31, forging heating: heating the heating furnace at full power to 35°C below the phase transition point Tβ, and keeping the temperature for 265 minutes.

[0119] Specifically, the phase transition point Tβ temperature of TC4 material is 950°C.

[0120] Step S32, placing the blank into the second mold, and upsetting the blank until it is flush with the second mold.

[0121] Step S33 , punching is performed using a fourth punch 8 , wherein the fourth punch 8 comprises a plate body and a column connected to the lower end of the plate body, and the outer diameter of the plate body is greater than the inner diameter of the inner cavity of the second fetal membrane 7 .

[0122] Step S4: profile rolling.

[0123] like Figure 7 As shown, specifically, the profile rolling includes the following steps:

[0124] Step S41, forging heating: the heating furnace is heated at full power to 35°C below the phase transition point Tβ, and the temperature is kept for 160 minutes.

[0125] Step S42, using the ring machine 9 to roll the tire membrane blank.

[0126] Specifically, the ring machine 9 includes a rotating outer roller 91, an inner roller 92 and two pressure rollers 93. The outer roller 91 is arranged vertically, and the inner side shape is the same as the inverted reducer. The inner roller 92 is arranged vertically and is a cylinder, and together with the outer roller 91, the thickness and shape of the tire membrane blank are rolled. The two pressure rollers 93 are arranged horizontally to roll the height of the tire membrane blank. During rolling, the reducer of the tire membrane blank faces downward at the large end and upward at the small end. After the special-shaped rolling step, the ratio of the height of the tire membrane blank to the wall thickness of the large end is ≤2.5.

[0127] Step S5, fetal membrane molding.

[0128] like Figure 3 , Figure 8 , Fig. 9 , Fig.10 and Fig.11 As shown, specifically, the fetal membrane molding includes the following steps:

[0129] Step S51, forging heating: heating the heating furnace at full power to 35°C below the phase transition point Tβ, and keeping the temperature for 135 minutes.

[0130] Step S52, one-time bending: the fetal membrane blank is placed in the first fetal membrane 1, and the first punch 2 is pressed downward to bend the fetal membrane blank, and the first punch 2 is an inverted frustum cone shape.

[0131] Specifically, the included angle between the generatrix of the first punch 2 and the top surface is 75°, and the beveling angle of the large end of the fetal membrane blank is 15°.

[0132] Step S53, secondary beveling: the second punch 3 presses down to bend the fetal membrane blank, and the second punch 3 is an inverted frustum cone type.

[0133] Specifically, the included angle between the generatrix of the second punch 3 and the top surface is 65°, and the beveling angle of the large end of the fetal membrane blank is 25°.

[0134] Step S54, three times of bending: the guide post 5 passes through the center of the fetal membrane blank and rests against the bottom of the first fetal membrane 1, the third punch 4 includes a square ring sleeved on the outside of the guide post 5 and an inverted cone ring arranged at the lower end of the square ring, the third punch 4 is pressed down until the upper end of the inverted cone ring is flush with the upper end of the first fetal membrane 1, the fetal membrane blank is upset and divided, the guide post 5 is a cylinder.

[0135] Specifically, the angle between the lower generatrix of the conical ring and the top surface is 35°, and the beveling angle of the large end of the fetal membrane blank is 55°.

[0136] Step S55, upsetting the pressure ring 6: the pressure ring 6 presses down to upset the fetal membrane blank until the upper end of the fetal membrane blank is flush with the upper end of the first fetal membrane 1 to obtain a forging. The pressure ring 6 is sleeved on the outside of the third punch 4. The pressure ring 6 is a square ring, and its outer diameter is larger than the inner diameter of the inner cavity of the first fetal membrane 1.

[0137] Step S6, annealing.

[0138] Specifically, the mixture is heated to 720° C., kept at this temperature for 90 minutes, and then air-cooled.

[0139] Step S7, detection.

[0140] Specifically, the detection includes the following steps:

[0141] Step S71, hardness inspection: 100% of the forgings are inspected for hardness, and the hardness requirement is HB(d)≥3.30mm.

[0142] Step S72, sampling: cutting a test ring from the forging body.

[0143] Step S73, physical and chemical testing: the test ring is subjected to physical and chemical testing according to the requirements of standard GJB 2744A-2007;

[0144] Step S74, rough machining: perform machining according to the drawing requirements.

[0145] Step S75, ultrasonic flaw detection: in accordance with the A1 level requirements in GB / T 5193-2007.

[0146] Test example:

[0147] The performance of the thick-walled shell forgings produced in the first to third embodiments was tested. The specific results are shown in Table 1.

[0148] Table 1

[0149] First embodiment Second embodiment Third embodiment Tensile strength(MPa) 975 950 1000 Yield strength(MPa) 900 870 920 Elongation after break (%) 14 12 16 Sectional shrinkage (%) 31 28 35

[0150] Test items:

[0151] Chemical composition: Meet the requirements of TC4 of GB / T 3620-2007.

[0152] Macrostructure: According to GJB 391 standard, the structure is not allowed to have cracks, pores, metal or non-metallic inclusions and other visually visible metallurgical defects, and should meet the 1-3 level in GJB 391.

[0153] Room temperature tensile test: According to GB / T 228 standard, tensile strength ≥865MPa, yield strength ≥825MPa, elongation after fracture ≥8%, and cross-sectional shrinkage ≥20%.

[0154] High-magnification structure: Forgings are allowed to have overburning, cracks and metallurgical defects that affect quality, and meet the requirements of Article 3.6 of GJB 2744A-2007.

[0155] Room temperature impact: in accordance with GB / T 229 standard, ≥24J.

[0156] Ultrasonic flaw detection: In accordance with GB / T 5193-2007 standard, in line with GB / T 5193-2007 A1 level.

[0157] Hardness: According to GB / T 231 standard, HB(d)≥3.3mm.

[0158] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0159] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for forming a thick-walled shell forging, characterized in that: The following steps are involved: Prefabricate the fetal membrane blank according to the size, the fetal membrane blank is a reducer, the large end of the reducer faces upwards and the small end faces downwards; Membrane formation: Forging heating: heat to 30℃~35℃ below the phase transformation point Tβ, keep warm for 45~135min; One-time bending: put the fetal membrane blank into the first fetal membrane, and press the first punch downward to bend the fetal membrane blank, and the first punch is an inverted frustum cone type; Secondary bending: The second punch presses down to bend the membrane blank, and the second punch is a frustum-shaped punch; Three times of bending: the guide pin passes through the center of the fetal membrane blank and presses against the bottom of the first fetal membrane. The third punch includes a square ring sleeved on the outside of the guide pin and an inverted cone ring arranged at the lower end of the square ring. The third punch is pressed down until the upper end of the inverted cone ring is flush with the upper end of the first fetal membrane, so as to upset and divide the fetal membrane blank. The guide pin is a cylinder. Pressing ring upsetting: The pressing ring presses and upsets the fetal membrane blank until the upper end of the fetal membrane blank is flush with the upper end of the first fetal membrane to obtain a forging. The pressing ring is sleeved on the outside of the third punch. The pressing ring is a square ring with an outer diameter larger than the inner diameter of the inner cavity of the first fetal membrane.

2. The method for forming a thick-walled shell forging according to claim 1, characterized in that: The included angle between the generatrix of the first punch and the top surface is 70° to 75°, the included angle between the generatrix of the second punch and the top surface is 60° to 65°, and the included angle between the generatrix under the conical ring and the top surface is 30° to 35°.

3. The method for forming a thick-walled shell forging according to claim 1, characterized in that: The step of prefabricating the fetal membrane blank according to size comprises: Cutting materials; Chamfering; Fetal membrane blank making: Forging heating: heat to 30℃~35℃ below the phase transformation point Tβ, keep warm for 175~265min; Put the blank into the second die, and upset the blank until it is flush with the second die; A fourth punch is used for punching, wherein the fourth punch comprises a plate body and a column connected to the lower end of the plate body, and the outer diameter of the plate body is greater than the inner diameter of the second fetal membrane cavity; Profile rolling: Forging heating: heat to 30℃~35℃ below the phase transformation point Tβ, keep warm for 70~160min; The tire membrane blank is rolled using a ring machine.

4. The method for forming a thick-walled shell forging according to claim 3, characterized in that: TC4 forged rods are used for cutting and smelted three times in a vacuum consumable arc furnace.

5. The method for forming a thick-walled shell forging according to claim 3, characterized in that: After the profile rolling step, the ratio of the tire membrane blank height to the large end wall thickness is ≤2.

5.

6. The method for forming a thick-walled shell forging according to claim 1, characterized in that: After the fetal membrane forming step, the method further comprises the following steps: Annealing: Heat to 700℃~720℃, keep warm for 90~120min, then air cool.

7. The method for forming a thick-walled shell forging according to claim 6, characterized in that: After the annealing step, a detection step is also included: Hardness inspection: 100% hardness inspection of forgings, hardness requirement HB ≥ 3.30mm; Sampling: Cut a test ring from the forging body; Physical and chemical: The test ring is subjected to physical and chemical tests according to the requirements of standard GJB 2744A-2007; Rough machining: Machining according to the requirements of the drawings; Ultrasonic flaw detection: in accordance with the A1 grade requirements of GB / T 5193-2007.

8. The method for forming a thick-walled shell forging according to claim 1, characterized in that: The weight percentage of each chemical element in the forging is: AL: 5.5~6.75%; V: 3.5~4.5%; Fe: ≤0.3%; C: ≤0.08%; N: ≤0.05%; H: ≤0.015%; O: ≤0.2%; Other elements: single ≤0.1%, total ≤0.4%; the balance is Ti.

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