A forging process and die for a single-vacuum 300M gear forging

Abstract

The application provides a forging process of single-vacuum 300M gear forging, which comprises the following steps: step one: blank preparation, including upsetting and blind hole punching; step two: die forging, the blanked forging is heated to 1100±10 DEG C, the heating and holding time of the cold material is 50-110 minutes, the blank is accurately placed in the die forging die during die forging, the die forging is carried out through a 40MN electric screw press, and it is ensured that the die forging is completed in one heating; step three: heat treatment, including normalizing and tempering, when normalizing, the forging is loaded into the furnace at a temperature of less than or equal to 750 DEG C, is kept at a temperature of 935 DEG C±10 for 150-180 minutes, is air-cooled to a temperature of less than or equal to 600 DEG C, and then is air-cooled; when tempering, the forging is loaded into the furnace at a temperature of less than or equal to 600 DEG C, is kept at a temperature of 720 DEG C±10 for 270-300 minutes, and is air-cooled. Through optimization of the forging process, accurate control of the deformation and temperature parameters, and combination of the specially-made forging die, the high-efficiency and high-quality production of the single-vacuum 300M gear forging is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to a single vacuum 300M gear forging process and die, belonging to the technical field of die forging. BACKGROUND

[0002] 300M steel is a high-strength low-alloy steel, which is widely used in many fields such as aircraft and aerospace due to its excellent mechanical properties and durability. However, the traditional smelting process has many shortcomings in the production of 300M steel, resulting in large differences in the main chemical composition and residual element allowable deviation of the raw material and the composition difference of the ingot head and tail; The present steel plant improves the production technology by adopting single vacuum smelting method, and develops a new type of single vacuum 300M steel based on the raw material; Therefore, developing a new type of forging process and its supporting die for the new type of single vacuum 300M steel is of great significance for improving the quality of 300M products and developing new materials.

[0003] The chemical composition of single vacuum 300M should meet the requirements of Table 1 and Table 2, and the deviation of the check analysis should not exceed the provisions of Table 3. The composition difference of the consumable remelted steel ingot head and tail should meet the requirements of Table 4.

[0004] Table 1 Main element chemical composition (wt%)

[0005] Element C Cr Ni Si Mo Mn V Content 0.40～0.43 0.70～0.95 1.65～2.00 1.45～1.80 0.30～0.50 0.60～0.90 0.05～0.10 Element S P S+P Al Ti Cu N Content ≤0.005 ≤0.010 ≤0.012 ≤0.03 ≤0.005 ≤0.20 ≤0.02

[0006] Table 2 Residual element chemical composition (wt%)

[0007]

[0008] Table 3 Allowable deviation (wt%)

[0009] Element C Cr Ni Si Mo Mn V Content ±0.01 ±0.05 ±0.05 ±0.05 ±0.03 ±0.03 ±0.01

[0010] Table 4 Ingot head and tail composition difference (wt%)

[0011] Element C Cr Ni Si Mo Mn V Cu Content ≤0.03 ≤0.07 ≤0.10 ≤0.10 ≤0.05 ≤0.15 ≤0.03 ≤0.05 SUMMARY

[0012] The present application provides a single vacuum 300M gear forging process and die, by optimizing the forging process, accurately controlling the deformation and temperature parameters, and combining with the special forging die, the efficient and high-quality production of single vacuum 300M gear forging is realized.

[0013] The technical scheme of the present application is as follows:

[0014] The present application provides a single vacuum 300M gear forging process, comprising the following steps:

[0015] Step one: blanking, including upsetting and punching blind hole, wherein, during upsetting, the raw material bar is Heating is performed with the heating temperature controlled at 1100±10℃ ), the cold material heating and holding time is 100-160 minutes (Note 1: the cold material holding time during heating is calculated at 0.4 min / mm-1.1 min / mm, and the hot material is calculated at 0.2 min / mm-0.8±0.1 min / mm, the hot material refers to the raw material with a temperature of ≥750℃), upsetting to H=220 mm±10 mm, the deformation amount of each hammering / way is controlled at less than 10%, uniform speed is used for pressing, and the pressing speed is less than 10 mm / s; when blind holes are punched, a punch is used, and after punching, the punch is used for rolling, the blank bulge and displacement are removed, the pressing amount of each hammering / way is not more than 20 mm, uniform speed is used for pressing, and the pressing speed is less than 10 mm / s, so as to eliminate the large R angle and ensure that the punching and rolling are completed in one heating.

[0016] Step two: die forging, the blanked forging is heated to 1100±10℃, the cold material heating and holding time is 50-110 minutes (the heating coefficient is the same as the above Note 1), during die forging, the blank is accurately placed in the die forging die, during die forging, first, compressed air is used to blow away the dirt in the die cavity, and the die lubricant is uniformly sprayed; then, the blank is placed in the die cavity along the shape of the cavity, the first hammer is used for positioning, the energy of the 40 MN electric screw press is 10%, the energy of the second hammer is 50%, the energy of the third hammer is 60%, and then the ejector rod is used for ejecting, so as to ensure that the die forging is completed in one heating.

[0017] Step three: heat treatment, including normalizing and tempering, during normalizing, the forging is ≤750℃ when being loaded into the furnace, 935℃±10 is used for holding for 150-180 minutes, air cooling is performed until ≤600℃, and then air cooling is performed; during tempering, the forging is ≤600℃ when being loaded into the furnace, 720±10℃ is used for holding for 270-300 minutes, and air cooling is performed.

[0018] Preferably, in the above die forging step, the die forging die includes a punch for blanking and upper and lower dies for forging, and the lower die is designed with an ejector rod, the diameter of the punch is the height is 45 mm-70 mm, and the draft angle is 5-15°; the maximum outer diameter of the ejector rod is the height is 109-139 mm, the draft angle is 5-10°, and the contact area between the ejector rod and the forging is reduced by designing the punching and skin connection position of the core of the forging to be lower, and the skin center is located at 1 / 4-1 / 3 lower of the thickness dimension of the forging.

[0019] Preferably, the separation position of the ejector rod and the lower die is designed to be 1 / 4 to 1 / 3 lower of the center of the bottom, so as to reduce the oxidation skin and other oil dirt impurities generated during forging from entering the ejector rod and the bottom of the die holder, and at the same time, the round corner design of the bottom of the die is retained, which is beneficial to the filling of the forging and the demolding of the forging.

[0020] ​Preferably, the above-mentioned billet preparation step optimizes the utilization rate of raw materials, avoids multiple forging processes, and controls the overall and local deformation of the forgings during the die forging process to be between 30% and 70%, so as to avoid overheating and burning of the forgings during the forging process and improve product quality and pass rate.

[0021] This invention also provides a mold for forging 300M gears in a single vacuum process, comprising a punch for blank preparation and upper and lower forging dies, wherein the lower die is designed with an ejector pin, and the diameter of the punch is... Height 45mm-70mm, draft angle 5-15°; maximum outer diameter of ejector pin The height is 109-139mm, the draft angle is 5-10°, and the contact area between the ejector pin and the forging is reduced by designing the core punching connection point of the forging to be slightly lower. The center of the connection point is located 1 / 4-1 / 3 of the thickness of the forging. The separation position of the ejector pin and the lower die is designed to be 1 / 4 to 1 / 3 of the bottom center.

[0022] Preferably, the separation position between the ejector pin and the lower die is designed with two steps to reduce impurities from entering the ejector pin and the bottom of the die base, while retaining the rounded corner design at the bottom of the die, which is beneficial for filling and demolding of the forging.

[0023] The beneficial effects of this invention are:

[0024] The forging process and mold design of this invention optimize the mold and ejector pin, solving the problems of forging demolding and the impact of oxide scale and impurities on forging production during the forging process. By punching blind holes in the process, the raw material loss in the production process of single vacuum 300M gear forgings is significantly reduced, multi-forging is avoided, and the overall and local deformation of the forgings during the die forging process is controlled within 30%-70%, thereby avoiding overheating and burning of the forgings during the forging process and improving product quality and pass rate. At the same time, the process parameters of forging and heat treatment of single vacuum 300M material are optimized and fixed to ensure the quality of forgings produced in batches. Attached Figure Description

[0025] Figure 1 It features a traditional mold design with the outer skin attached.

[0026] Figure 2 This invention relates to the continuous skin design of the forging die;

[0027] Figure 3 This is a diagram of a traditional mold ejector pin. Figure 1 ;

[0028] Figure 4 This is a diagram of a traditional grinding wheel ejector pin. Figure 2 ;

[0029] Figure 5 This is a schematic diagram of the ejector pin of the forging die of the present invention;

[0030] Figure 6 is a schematic diagram of a traditional die forging process using a round blank to directly die forging;

[0031] Figure 7 is a schematic diagram of a traditional die forging process using a round blank to directly die forging;

[0032] Figure 8 is a schematic diagram of a traditional die forging process using a round blank to directly die forging;

[0033] Figure 9 is a schematic diagram of a traditional die forging process using a round blank to directly die forging;

[0034] Figure 10 is a schematic diagram of a traditional die forging process using a round blank to directly die forging;

[0035] Figure 11 is a schematic diagram of a traditional die forging process using a round blank to directly die forging. DETAILED DESCRIPTION

[0036] The application will be further described below in conjunction with the drawings. The following examples are only used to more clearly illustrate the technical solutions of the application, and cannot be used to limit the protection scope of the application.

[0037] The application provides a single-vacuum 300M gear forging forging process, comprising the following steps:

[0038] Step one: blank making, including upsetting and punching blind holes, wherein, when upsetting, the raw material bar is heated, and the heating temperature is controlled at 1100±10℃ The cold material heating and holding time is 100-160 minutes (note 2: the cold material holding time during heating is calculated as 0.4 min / mm-1.1 min / mm, and the hot material is calculated as 0.2 min / mm-0.8±0.1 min / mm, and the hot material refers to the raw material with a temperature of 750℃ or higher), the upsetting is to H=220±10, the deformation amount of each hammering / way is controlled to be less than 10%, the uniform speed is pressed, and the pressing speed is less than 10 mm / s; when punching blind holes, a punch is used, the hole is rolled after the punch is punched, the blank bulge and displacement are removed, the pressing amount of each hammering / way is not more than 20 mm, the uniform speed is pressed, and the pressing speed is less than 10 mm / s, so as to eliminate the large R angle and ensure that the punching and rolling are completed in one time;

[0039] ​Step two: die forging, heating the blanked forging to 1100±10℃, the heating and holding time of the cold material is 50-110 minutes (the heating coefficient is the same as the above note 2), during die forging, the blank is accurately placed in the die forging die, during die forging, first use compressed air to blow off the dirt in the die cavity, and uniformly spray the die lubricant; then, the blank is placed in the die cavity along the shape of the cavity, the first hammer is lightly hit to position, the energy of the 40MN electric screw press is 10%, the energy of the second hammer is 50%, the energy of the third hammer is 60%, and then the ejector rod is ejected to ensure that the die forging is completed in one heating;

[0040] Step three: heat treatment, including normalizing and tempering, during normalizing, the forging is ≤750℃ into the furnace, 935℃±10 is held for 150-180 minutes, air cooled to ≤600℃, and then air cooled; during tempering, the forging is ≤600℃ into the furnace, 720±10℃ is held for 270-300 minutes, and air cooled.

[0041] Preferably, in the above die forging step, the die forging die includes a punch for blanking and upper and lower dies for forging, and the lower die is designed with an ejector rod, the diameter of the punch is 50, the draft angle is 10°; the maximum outer diameter of the ejector rod is 139, the draft angle is 10°, and the contact area of the ejector rod with the forging is reduced by designing the punching position of the core of the forging to be lower, and the center of the skin is located at 1 / 4-1 / 3 lower than the thickness dimension of the forging.

[0042] Preferably, the separation position of the ejector rod and the lower die is designed to be 1 / 4 to 1 / 3 off-center at the bottom to reduce the oxidation scale and other impurities generated during forging from entering the ejector rod and the die seat bottom, while retaining the round corner design of the die bottom, which is beneficial to the filling of the forging and the demolding of the forging.

[0043] Preferably, the blanking step optimizes the utilization rate of raw materials to avoid multiple forging, and controls the overall and local deformation of the forging during die forging to be 30%-70% to avoid overheating and overburning of the forging during forging, thereby improving the product quality and qualification rate.

[0044] As shown in Figure 6 , the traditional die forging process uses round blank directly for die forging; the demand for raw materials is large, the utilization rate of raw materials is 85%, and the core deformation is large and the core temperature is high during die forging, which affects the quality of single vacuum 300M forgings.

[0045] The effective area of the forging has an equivalent strain of 0.75-2.5mm / mm, and the calculated deformation is 50%-92%, among which the core deformation is the largest, about 90%, and the core deformation is in the critical deformation zone. The results are shown in Figure 7 .

[0046] As shown in Figure 8As shown, the optimized die forging process adopts round blank upsetting + punching blind hole; the raw material is reduced, and the raw material utilization rate reaches 94%, while the core deformation in the die forging process is reduced, and the quality of the single vacuum 300M forged piece is improved.

[0047] The effective area equivalent strain of the forged piece is 0.4-1mm / mm, and the calculated deformation is about 32%-65%, and the core deformation is about 65%. Figure 9 .

[0048] Example 1:

[0049] A die for forging a single vacuum 300M gear forged piece, comprising a punch 4 for making a blank (as shown in Figure 10 ), and an upper die 1 and a lower die 2 for forging (as shown in Figure 11 ), and a ejector rod 3 is designed in the lower die 2, the diameter of the punch 4 is , the height is 50, and the draft angle is 10°; the maximum outer diameter of the ejector rod 3 is , the height is 139, and the draft angle is 10°, and the contact area of the ejector rod 3 with the forged piece is reduced by designing the core punching and skin connecting position of the forged piece to be lower, and the center of the skin connecting is located at the lower 1 / 4-1 / 3 of the thickness dimension of the forged piece, and the separation position of the ejector rod 3 and the lower die 2 is designed to be 1 / 4 to 1 / 3 from the center of the bottom.

[0050] Preferably, the separation position of the ejector rod 3 and the lower die 2 is designed with two steps to reduce the impurities into

[0051] As shown in Figure 1 , the traditional gear forged piece, the die center punching and skin connecting position is designed at the middle position of the forged piece, the contact area of the ejector rod and the forged piece is large, the ejector rod is easy to stick to the body of the forged piece, and the forged piece is difficult to be separated from the ejector rod;

[0052] As shown in Figure 2 , the improved die design, the core punching and skin connecting position of the forged piece is designed to be lower, and the center of the skin connecting is located at the lower 1 / 4-1 / 3 of the thickness dimension, the contact area of the forged piece and the ejector rod is smaller, and the forged piece is easier to be demoulded;

[0053] As shown in Figures 3-4 , the old ejector rod design, due to the oxidation skin and other oil impurities generated during the forging process of the forged piece, and due to the gap between the ejector rod and the die, the impurities accumulate at the bottom of the die holder, causing the ejector rod to not fall completely, exceeding the die by 2-3mm, so that the forged piece and the ejector rod are deformed, affecting production;

[0054] As shown in Figure 5 , the improved ejector rod design, the separation position of the ejector rod and the lower die is designed to be 1 / 4 to 1 / 3 from the center of the bottom, one is that when the impurities fall, the ejector rod and the lower die have two steps, reducing the impurities into the ejector rod and the die holder; two is that the die holder bottom corner design is retained, which is beneficial to the filling of the forged piece and the demoulding of the forged piece, and the planar machining and polishing is convenient.

[0055] Example 2

[0056] A forging process for a single vacuum 300M gear forging, comprising the following steps:

[0057] Step one: blanking (upsetting + punching blind hole)

[0058] Blanking of raw material bar Blanking is performed using an 8MN fast forging machine, heating at 1100±10℃ for 100-160 minutes, first step upsetting, bar upsetting to H=220±10, deformation control at 10% or less per hammer / pass, uniform speed down, down speed less than 10mm / s;

[0059] Second step punching blind hole, using punching blind hole, after punching, round with punch, remove blank bulge and displacement, per hammer / pass down pressure not more than 20mm, uniform speed down, down speed less than 10mm / s, to eliminate large R angle, ensure one-time completion of punching and rounding.

[0060] Step two: die forging

[0061] The forging is heated again to 1100±10℃, heating for 50-110 minutes; during die forging, the blank is precisely placed in the specially designed forging die, during die forging, first use compressed air to blow off dirt in the die cavity, and evenly spray die lubricant; then, the blank is placed in the die cavity along the shape of the cavity, the first hammer is used for positioning, 40MN electric screw press energy 10%, second hammer energy 50%, third hammer energy 60%, then the ejector rod is ejected, to ensure one-time completion of die forging;

[0062] Step three: heat treatment

[0063] The forged forging after die forging is immediately sent to the heat treatment furnace, using normalizing + tempering system;

[0064] Normalizing, the forging is ≤750℃ into the furnace, 935±10℃ for 150-180 minutes, air cooling, 30min cooling to ≤600℃ (using air cooling method for rapid cooling, equipped with at least 8 fans, fan speed set to 1200r / min), then air cooling;

[0065] Tempering, the forging is ≤600℃ into the furnace, 720±10℃ for 270-300 minutes, air cooling, cooling to <300℃ for 6-8h.

[0066] The single vacuum 300M gear forging product developed according to the embodiment 1 has a thickness size reaching the nominal size of the forging +2, a forging size tolerance +3, a better forming effect, no scrap situation, and a forging raw material utilization rate reaching more than 90%.

[0067] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and modifications without departing from the technical principles of the present application, and these improvements and modifications should also be considered as the protection scope of the present application.

Claims

1. A forging process for a single-vacuum 300M gear forging, characterized in that, Includes the following steps: Step 1: Billet preparation, including upsetting and blind hole punching. During upsetting, the raw material bar stock φ150 mm×415 mm is heated at a temperature of 1100±10℃. The holding time for heating the cold material is 100-160 minutes. Upsetting is performed to H=220 mm±10 mm. The deformation per hammer / pass is controlled below 10%. The material is pressed down at a uniform speed of less than 10 mm / s. When punching blind holes, a punch of (φ110±10) mm×(50±10) mm is used. After punching, the hole is rolled with the punch head. The pressing amount per hammer / pass does not exceed 20 mm. The material is pressed down at a uniform speed of less than 10 mm / s. Step 2: Die forging. Heat the forging after billet preparation to 1100±10℃. The heating and holding time of cold material is 50 to 110 minutes. During die forging, place the billet accurately in the die forging mold and perform die forging through a 40MN electric screw press to ensure that the die forging is completed in one pass. Step 3: Heat treatment, including normalizing and tempering. During normalizing, the forgings are loaded into the furnace at ≤750℃, held at 935℃±10℃ for 150~180 minutes, air-cooled to ≤600℃, and then air-cooled. During tempering, the forgings are loaded into the furnace at ≤600℃, held at 720±10℃ for 270~300 minutes, and then air-cooled.

2. The forging process for a single-vacuum 300M gear forging according to claim 1, characterized in that, In step two, the specific steps of die forging are as follows: First, use compressed air to blow away the dirt inside the mold cavity and spray the mold lubricant evenly. Then, place the billet in the mold cavity along the shape of the cavity. The first hammer blow is used to position it. The energy of the 40MN electric screw press is 10%, the energy of the second hammer is 50%, and the energy of the third hammer is 60%. Then the ejector rod is pushed out to ensure that the forging is completed in one pass.

3. The forging process for a single-vacuum 300M gear forging according to claim 1, characterized in that, The billet preparation step optimizes the utilization rate of raw materials, avoids multiple forging processes, and controls the overall and local deformation of the forgings during the die forging process to be between 30% and 70%, thereby preventing overheating and burning of the forgings during the forging process and improving product quality and pass rate.

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