A forging method for improving the structure uniformity of a high-temperature alloy journal forging

Abstract

The present application relates to the field of forging and die design, and particularly relates to a forging method for improving the structure uniformity of high-temperature alloy shaft neck forgings. The method comprises the following steps: blanking; performing first die forging: laying a layer of aluminum silicate thermal cotton on the upper end face of the bar, and using the upper punch of the upper die to perform forging; performing second die forging: lifting the upper die, placing iron sheet on the end face of the blank, placing release agent on the iron sheet, using the upper punch of the upper die to perform forging, stopping when the process requirement is met, and performing pressure maintaining; simultaneously starting the lower piercing device of the press, driving the lower punch to upwardly forge, stopping when the drawing requirement is met, maintaining pressure for 10 seconds, lifting the hammer after the maintaining, and completing the die forging; in the process, the upper die and the lower die cavity surface constrain the outer circular area of the blank, so that the deformation amount of the blank under three-way compressive stress is more uniform; the forging die used in the die forging comprises an upper die, a lower die and a lower punch; the upper die comprises an upper die base body and an upper punch.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of forging and die design, in particular to a forging method for improving the uniformity of the microstructure of a high-temperature alloy shaft neck forging. BACKGROUND

[0002] A shaft neck-shaped forging for an aero-engine is made of high-temperature alloy, has a diameter of about 850 mm, a height of about 730 mm, and a structure of a large diameter at one end with a blind hole of a certain depth and a smaller diameter at the other end. The forging has high performance and microstructure requirements, and the average grain size of the forging should be grade 10 or finer, and the flaw detection requirement is AA level. For such a forging, conventional forging uses free upsetting to prepare the rough forging, and then performs die forging to achieve the forging.

[0003] In order to ensure that the microstructure and performance of the forging meet the design requirements, on the one hand, the depth of the blind hole is increased in the forging design stage to increase the deformation of the core of the forging. On the other hand, the weight of the raw material is increased, the machining allowance of the forging is increased, the shape size of the forging billet is optimized by means of simulation software, the positions of the small deformation zone and the cold die layer are adjusted, and finally the machining is removed. The forging produced by this method solves the problem of the forging qualification rate, but increases the consumption of raw materials, resulting in an increase in the manufacturing cost of the forging and a long manufacturing cycle. SUMMARY

[0004] The purpose of the present application is to improve the forging qualification rate while reducing the consumption of raw materials of the forging, improve the production efficiency of the forging, reduce the production cost of the forging, and shorten the production cycle of the forging.

[0005] TECHNICAL SCHEME

[0006] The present application provides a forging method for improving the uniformity of the microstructure of a high-temperature alloy shaft neck forging, comprising:

[0007] Blanking;

[0008] Performing first die forging: laying a layer of aluminum silicate thermal insulation cotton on the upper end face of the bar, and using the upper punch of the upper die to perform forging;

[0010] Performing second die forging: lifting the upper die, placing an iron sheet on the end face of the blank, placing a release agent on the iron sheet, using the upper punch of the upper die to perform forging, stopping when the process requirement is met, and performing pressure holding; at the same time, starting the lower punch of the lower die to perform upward forging, stopping when the drawing requirement is met, pressure holding for 10 seconds, lifting the hammer, and completing the die forging;

[0011] In this process, the upper die cavity surface and the lower die cavity surface constrain the outer circular area of the blank, so that the deformation of the blank is more uniform under three-directional compressive stress;

[0012] The forging die used in the above die forging includes an upper die, a lower die, and a lower punch; the upper die includes an upper die base and an upper punch;

[0012] The upper die base has a cylindrical blind hole in one side and a bolt groove or a pressing plate groove for connecting equipment in the other side; the upper punch has a cylindrical mounting end in one end and a conical surface and a spherical surface cavity surface in the other end; the cylindrical recess surface of the upper die base and the cylindrical mounting end of the upper punch are connected by hot embedding; the lower die and the lower punch are gap fitted; the lower punch is located in the lower part of the lower die cavity.

[0013] Further, the upper end of the lower punch is a rotary body boss as a cavity surface, the side surface is a partial cylindrical surface and a second conical surface, the cylindrical surface is gap fitted with the lower die cavity, the diameter is 2-4 mm smaller than the diameter of the inner hole of the die, the height of the cylindrical surface is 50-70 mm, the upper end of the second conical surface is connected with the cylindrical surface through an arc surface with a diameter of 10 mm, the slope of the second conical surface is 5-7°, and the height of the second conical surface is 30-50 mm.

[0014] Further, the cavity size of the upper punch is 1.01 times of the size of the forged piece, the cavity depth H of the lower die is 1.01 times of the height of the forged piece increased by 20-50 mm, the remaining cavity size of the lower die is 1.01 times of the size of the forged piece, and the cavity size of the lower punch is 1.004 times of the size of the forged piece.

[0015] Further, the depth of the circular recess surface of the upper die base is 120-160 mm, after the cylindrical mounting end of the upper punch is hot embedded with the upper die base, the remaining height is a cylindrical step and a punch cavity boss, the height of the cylindrical step is 50-100 mm, and the cylindrical step serves as an upper die guide surface during installation of the upper die and the lower die and during forging.

[0016] Further, the upper end of the lower die 2 has a first conical surface and a cylindrical surface from top to bottom;

[0017] The upper end of the first conical surface is large, and the lower end is small, the height of the first conical surface is 20-25 mm, the included angle with the cylindrical surface is 5°, the conical surface is connected with the impact surface of the lower die by an arc surface with a diameter of 6-10 mm, and the lower end of the conical surface is a die cavity surface;

[0018] The lower end of the cylindrical surface of the lower die is connected with a cavity surface, and the cavity depth is made according to the hot forged piece.

[0019] Further, the pressing speed of the upper punch is 4-10 mm / s, and the pressing speed of the lower punch is 4-6 mm / s.

[0020] Further, after the second die forging is performed, the method further comprises:

[0021] The forged piece is pad cooled to room temperature;

[0022] The forged piece is hot machined;

[0023] The processed forged piece is heat treated;

[0024] The forged piece after heat treatment is detected in macrostructure, microstructure and performance.

[0025] Further, the material of the lower punch is high-temperature alloy GH4196.

[0026] Beneficial effects: the forged piece obtained by the method has greatly improved material utilization rate of the forged piece, high qualified rate of the forged piece, stable quality of the forged piece, short production cycle and low cost.

[0027] A forging die is designed, in the forging process, the blank is deformed under the constraint of the upper and lower dies, the lower punch can press the bottom of the blank, the deformation amount of the bottom of the blank is increased, the small deformation area of the blank at the bottom of the lower die is avoided, and the deformation uniformity of the forged piece is improved. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is a schematic diagram of the forging die structure.

[0029] Figure 2 It is a schematic diagram of the upper die structure.

[0030] Figure 3 It is a schematic diagram of the lower die structure.

[0031] Figure 4 It is a microstructure diagram of the forged piece of the embodiment. DETAILED DESCRIPTION

[0032] The application provides a forging method for improving the uniformity of high-temperature alloy shaft neck forged pieces, and the specific process is as follows:

[0033] Step 1: blanking, first, the original material bar with a diameter of 410 mm and a length of 705 mm is rounded to R35~R50 mm at one end; the other end is processed into a taper surface with an angle of 80° with the bar, the small end diameter of the taper surface is 370 mm, and the taper surface and the end surface and the taper surface and the outer circular surface of the bar are connected by a diameter of 20 mm arc surface.

[0034] Step 2: then heat in the preheating furnace for 10-15 minutes, the furnace temperature is 100-150 DEG C;

[0035] Step 3: the preheated bar is taken out, and a protective lubricant is sprayed on the surface of the bar;

[0036] Step 4: the bar is placed in the heating furnace and heated to the forging temperature. At the same time, the upper die 1 and the lower die 2 and the lower punch 3 are also heated, and the heating temperature is 380-480 DEG C.

[0037] Step 5: perform die forging: the lower die cavity upper surface is paved with a layer of aluminum silicate insulation cotton, and the bar is vertically placed in the heated lower die cavity surface. A layer of aluminum silicate insulation cotton is paved on the upper end surface of the bar, and forging is performed, and the height is stopped at 160 mm; wherein the forging temperature is 1060℃, and the pressing speed is 10 mm / s. The upper die is lifted, the end surface of the blank is placed with iron sheet, the iron sheet is placed with release agent, and die forging is performed again. The forging is performed, and the height is stopped at 3 mm to perform pressure holding; at the same time, the lower punch 3 is driven upward by the lower perforating device of the press, and the pressing stroke H4 is stopped at 25-50 mm, and the hammer is lifted after pressure holding for 10 seconds, and the die forging is completed. In this process, the upper die and the lower die cavity surface constrain the outer circular area of the blank, so that the deformation amount of the blank is more uniform under three-way pressure stress.

[0038] Step 6: pad the forged piece to room temperature by air cooling.

[0039] Step 7: hot pre-machining of the forged piece.

[0040] Step 8: aging treatment of the machined forged piece.

[0041] Step 9: macrostructure, microstructure and performance detection of the heat treated forged piece.

[0042] The upper die 1 in step 4 includes an upper die base body 11 and an upper punch 12. The upper die base body 11 has a cylindrical blind hole in the middle of one side and a bolt groove or a pressing plate groove connected with equipment on the other side. The upper punch 12 has a cylindrical mounting end on one end and a conical surface and a spherical surface cavity surface on the other end. The cylindrical recess surface of the upper die base body 11 is hot-embedded with the cylindrical mounting end of the upper punch 12. Further, the depth H1 of the circular recess surface of the upper die base body 11 is 120-160 mm, and the remaining height H2 of the cylindrical step and the punch cavity boss after the cylindrical mounting end of the upper punch 12 is hot-embedded with the upper die base body 11 is 50-100 mm, which serves as the upper and lower die installation and the upper die guide surface DX1 during forging.

[0043] The lower die 2 in step 4 has a first conical surface DX2 and a cylindrical surface DX3 on the upper end. The diameter of the cylindrical surface DX3 is 2-4 mm larger than that of the upper die cylindrical surface DX1. Further, the first conical surface DX2 is large on the upper end and small on the lower end, the height of the first conical surface DX2 is 20-25 mm, the angle between the cylindrical surface and the first conical surface DX2 is 5°, and the conical surface is connected with the impact surface of the lower die 2 by an arc surface with a diameter of 6-10 mm; the lower end of the conical surface is the die cavity surface.

[0044] Further, the lower die cylindrical surface DX3 is connected with the lower end cavity surface, and the cavity depth is made according to the hot forged piece.

[0045] The upper end of the lower punch 3 in the step 4 is a rotary body boss which is a cavity surface, the side surface is a partial cylindrical surface 31 and a second conical surface DX4, the cylindrical surface 31 is matched with the cavity gap of the lower die 2, the diameter is 2-4mm smaller than the diameter of the inner hole of the die, the height of the cylindrical surface 31 is 50-70mm, the upper end of the second conical surface DX4 is connected with the cylindrical surface through an arc surface with a diameter of 10mm, the slope of the second conical surface DX4 is 5-7°, and the height of the second conical surface DX4 is generally 30-50mm.

[0046] Further, the cavity size of the upper punch 12 is 1.01 times of the size of the forged piece, the cavity depth H of the lower die 2 is 1.01 times of the height of the forged piece increased by 20-50mm, the remaining cavity size of the lower die 2 is 1.01 times of the size of the forged piece, and the cavity size of the lower punch 3 is 1.004 times of the size of the forged piece.

[0047] Further, the raw material of the upper die base 11 and the lower die 2 adopts a medium-temperature hot work die steel, the raw material of the upper punch 12 adopts a high-temperature hot work die steel, and the raw material of the lower punch 3 adopts GH4196.

[0048] The bar specification is a rough shape with uniform deformation distribution after simulation optimization design. The deformation of the rough shape in the die forging process is between 25% and 70%.

[0049] Example 1

[0050] A rear journal forging for an aero-engine, made of GH4169, with a diameter of about 650mm and a height of about 630mm, has a large diameter at one end with a blind hole of a certain depth, a smaller diameter at the other end, and a batch quantity of 3.

[0051] Blanking, first, the raw material bar with a diameter of 410mm and a length of 705mm is rounded to R40 at one end, and a positioning bevel is machined at the other end. Then, the bar is heated to the forging temperature in a heating furnace. At the same time, the die is also heated to a temperature of 420℃. Die forging is performed, and the heated bar is vertically placed in the heated lower die cavity, which is covered with a layer of aluminum silicate insulation cotton. The bar is vertically placed in the lower die cavity with the guide bevel facing down. A layer of aluminum silicate insulation cotton is placed on the upper end surface of the bar, and forging is performed, and the height is stopped at 160mm. The forging temperature is 1060℃, and the pressing speed is 10mm / s. The upper die is lifted, an iron sheet is placed on the end surface of the blank, a release agent is placed on the iron sheet, and the die forging is performed again, and the height is stopped at 3mm. The pressure is maintained, and the lower punch is driven upward by the lower punch device of the press. The pressing stroke is 35mm, and the pressure is maintained for 10 seconds before the hammer is lifted. The die forging is completed, and the pressing speed is 3mm / s. In this process, the deformation of the blank is more uniform under three-way pressure stress.

[0052] The blank is raised and air-cooled to room temperature.

[0053] The forged piece after heat treatment is subjected to macrostructure, microstructure and performance detection, and the microstructure of the forged piece is as shown in Figure 4 .

[0054] The qualified rate of the forged piece is increased to 100%, the material utilization rate from the bar to the rough machining piece is increased by 10%, the and qualified rate of the forged piece is increased, the raw material cost of the forged piece production is reduced, the batch production stability of the forged piece quality is ensured, the production efficiency of the forged piece is greatly increased, and meanwhile the production cycle of the forged piece is shortened.

Claims

1. A forging method for improving the microstructural uniformity of a high temperature alloy journal forging, characterized by, The method comprises the following steps: Blanking; First die forging: laying a layer of aluminum silicate insulation cotton on the end face of the bar, using the upper punch of the upper die to perform forging; Second die forging: lifting the upper die, placing iron sheet on the end face of the blank, placing release agent on the iron sheet, using the upper punch of the upper die to perform forging, stopping when the process requirement is met, and performing pressure holding; meanwhile, starting the lower punch of the lower die to perform upward forging, stopping when the drawing requirement is met, pressure holding for 10 seconds, lifting the punch, and completing the die forging; In this process, the upper die and the lower die cavity surface constrain the outer circular area of the blank, so that the deformation of the blank is more uniform under three-way pressure stress; The upper end of the lower punch is a rotary body boss as the cavity surface, the side surface is a partial cylindrical surface and a second conical surface, the cylindrical surface is gap-fitted with the lower die cavity, the diameter of the cylindrical surface is 2-4 mm smaller than the diameter of the inner hole of the die, the height of the cylindrical surface is 50-70 mm, the upper end of the second conical surface is connected with the cylindrical surface through a circular arc surface with a diameter of 10 mm, the inclination of the second conical surface is 5-7°, and the height of the second conical surface is 30-50 mm; The pressing speed of the upper punch is 4-10 mm / s, and the pressing speed of the lower punch is 4-6 mm / s; After the second die forging, the method further comprises the following steps: Performing pad air cooling of the forged piece to room temperature; Performing hot pre-machining of the forged piece; Performing heat treatment of the machined forged piece; Performing macrostructure, microstructure and performance detection of the forged piece after the heat treatment is completed; The forging die used in the die forging comprises an upper die, a lower die and a lower punch; the upper die comprises an upper die base and an upper punch; One side of the upper die base is provided with a cylindrical blind hole in the middle, and the other side is provided with a bolt groove or a pressing plate groove connected with equipment; one end of the upper punch is provided with a cylindrical mounting end, and the other end is provided with a conical surface and a spherical cavity surface; the cylindrical recess surface of the upper die base is hot-embedded with the cylindrical surface of the upper punch; the lower die and the lower punch are gap-fitted; and the lower punch is located at the lower part of the lower die cavity.

2. The forging method according to claim 1, characterized by, The cavity size of the upper punch is 1.01 times the size of the forged piece, the cavity depth of the lower die is 1.01 times the height of the forged piece increased by 20-50 mm, the remaining cavity size of the lower die is 1.01 times the size of the forged piece, and the cavity size of the lower punch is 1.004 times the size of the forged piece.

3. The forging method according to claim 1, characterized by, The depth of the circular recess surface of the upper die base is 120-160 mm, after the cylindrical mounting end of the upper punch is hot-embedded with the upper die base, the remaining height is a cylindrical step and a punch cavity boss, the height of the cylindrical step is 50-100 mm, and the cylindrical step serves as the upper die guide surface during the installation of the upper die and the lower die and the die forging.

4. The forging method according to claim 3, characterized in that, The upper end of the lower die is provided with a first conical surface and a cylindrical surface from top to bottom, and the diameter of the cylindrical surface is 2-4 mm larger than that of the cylindrical surface of the upper die; The upper end of the first conical surface is large, and the lower end is small, the height of the first conical surface is 20-25 mm, the included angle between the first conical surface and the cylindrical surface is 5°, the conical surface is connected with the impact surface of the lower die through a circular arc surface with a diameter of 6-10 mm, and the lower end of the conical surface is the die cavity surface; The lower end of the cylindrical surface of the lower die is connected with the cavity surface, and the cavity depth is designed according to the hot forged piece.

5. The method of claim 1, wherein, The material of the lower punch is high-temperature alloy GH4196.

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