Forging forming method for sickle-shaped die forging

Abstract

The invention belongs to the field of structural part forging, and particularly relates to a forging forming method for a sickle-shaped die forging. By designing sickle-shaped rough blank and rough blank forging steps and adopting a special tool to be matched with a moulding bed, the manufacturing difficulty of the sickle rough blank is effectively reduced, the quality stability of the rough blank and the conformity of the rough blank and a die forging are improved, it is guaranteed that the rough blank can be completely placed in a die cavity, the rough blank is well matched with a finish forging die, and the die forging efficiency is improved. The defects such as die forging heating number and clamping damage and folding in the die forging process are reduced, original die forging multi-heating-number forming is improved to die forging one-heating-number forming, the problems that the die forging heating number is large, deformation is small, forged pieces are coarse in grain and unqualified in performance are effectively solved, meanwhile, the material utilization rate is greatly increased, and the qualified rate of the forged pieces and production benefits are improved.

Description

Technical Field

[0001] The invention belongs to the field of structural part forging, and in particular relates to a forging method for a sickle-shaped die forging. Background Art

[0002] Among the structural die forgings used in my country's aviation aircraft, such as rocker arms, cranks, piston rods, etc., most of these forgings are similar to the "sickle shape". The forging structure is complex, often containing high bosses, branches, thin webs and other difficult-to-form structures, and the cross-section mutation is large, and the height difference is large. Due to the above structural characteristics, this type of die forgings has complex rough forging steps, difficult operation, large rough size deviation, and the rough cannot be accurately placed in the die cavity during the die forging process, making die forging difficult, with a low pass rate and low material utilization.

[0003] In actual production, for "sickle-shaped" die forgings with a head-to-rod cross-sectional ratio ≥ 3, since the cross-sectional area of ​​the sickle part of the forging is much larger than the cross-sectional area of ​​the rod and there is a large height difference between the two parts, it is difficult to make such die forgings in rough form. In order to meet the cross-sectional area of ​​the sickle part, larger bars are often used. During the process of drawing the rod, the material needs to be divided first. When the required rod length of the rod is less than 1 / 3 of the rod height, the end of the rod is prone to concave during drawing, resulting in folding and resulting in rough form scrapping. In order to ensure that the sickle part of the die forging is filled, the margin of the rough sickle part is often increased, and the rough sickle part covers the entire cavity of the sickle part of the forging. This method results in extremely low material utilization, which is often less than 60%; and the rough part exceeds the cavity and is placed at the bridge part of the die. During die forging, the rough blank at the bridge part is split out to form burrs, which cannot be used for filling forgings. In addition, the burr thickness is small and the cooling speed is fast, which leads to increased deformation resistance and inability to continue forging. Subsequent die forging 2-3 times is required to ensure that the forging is full.

[0004] In the actual production process, for titanium alloy forgings such as TC21 and TC18 that need to be forged by β or near β, it is necessary to ensure sufficient deformation and appropriate forging temperature, and the forgings are formed by one fire. The structure and performance of the forgings are the best. A-100 ultra-high strength steel, 300M alloy steel, etc. are forged by multiple fires and small deformation, which is prone to coarse grains and unqualified performance. Summary of the invention

[0005] Purpose of the invention: To provide a forging method for sickle-shaped die forgings, so as to improve the quality stability of the "sickle-shaped" die forgings and the qualified rate of the die forgings.

[0006] Technical solution:

[0007] A forging method for a sickle-shaped die forging, wherein the cross section of the sickle head is larger than the cross section of the stem, the method comprising:

[0008] Step 1: Use a free forging hammer or a free forging press to upset and shape the bar material into a rectangular blank, wherein the cross section of the rectangular blank is smaller than the cross section of the sickle head and larger than the cross section of the rod;

[0009] Step 2: Use a free forging hammer or a free forging press to press the rectangular blank at a right angle to form an inclined surface to obtain a first blank; then divide the first blank along the length direction according to the blank volume required for the sickle blank head and the rod, and then lengthen the rod position and ensure that the transition is an inclined surface to obtain a second blank;

[0010] Step 3: insert the rod of the second blank into the lower die of the tire mold, and forge it with a free forging hammer or a free forging press. For the blank with a simple upper end face shape of the sickle head, use a pressing plate and a hammer anvil to upset and expand it to the final size of the head. For the blank with a complex upper end face shape of the sickle head, first use a pressing plate and a hammer anvil to upset and expand the second blank, and then use the upper die of the tire mold to press it to the final size of the head to obtain a third blank;

[0011] Step 4: Take the third blank out of the mold, and use a free forging hammer or a free forging press to lengthen the rod portion to obtain the final desired "sickle-shaped" blank;

[0012] Step 5: Place the "sickle-shaped" rough mold into a heating furnace and heat it for a certain period of time. After it comes out of the furnace, quickly transfer it to the final forging die. During forging, use a counter-hammer or press to slowly press down for positioning, so that the rough mold moves down along the die slope, and then hammer or press down to obtain the final die forging.

[0013] Preferably, in step 2, the angle θ2 between the inclined surface pressed into the first blank and the upper end surface is 135° to 180°.

[0014] Preferably, in step 2, the relationship between the width b1 reserved on the upper end surface of the first blank and the width b of the rectangular blank is: b1 = 1 / 3b.

[0015] Preferably, in step 2, the angle between the head and the stem of the second blank satisfies γ2: γ2 = γ1 ± 10°, wherein γ1 is the angle between the head and the stem of the final desired "sickle-shaped" blank.

[0016] Preferably, in step 2, the single pressing amount in the stretching process is 20-30 mm.

[0017] Preferably, in step three, the single-side gap between the second blank thickness δ and the tire mold opening thickness δ2 is 10-30 mm.

[0018] Preferably, in step four, the final required height difference Δh between the head and the rod of the "sickle-shaped" rough forging satisfies: 2 / 3ΔH≤Δh<ΔH, γ1=γ±10°, θ1=θ±10°, wherein γ is the angle between the head and the rod of the forging, and γ1 is the final required angle between the head and the rod of the "sickle-shaped" rough forging.

[0019] Preferably, in step 4, when the blank is stretched, the feeding amount of each hammer is 30-50 mm, and the pressing amount of each hammer is 20-30 mm.

[0020] Preferably, in step five, when a press is used for forging, for TC18 and TC21 titanium alloys, the pressing speed is ≤5 mm / s; for A-100 ultra-high strength steel and 300M alloy steel, the pressing speed is ≤10 mm / s.

[0021] Beneficial effects:

[0022] The present invention effectively reduces the difficulty of making sickle blanks, improves the quality stability of the blanks, and the conformity of the blanks with die forgings by designing reasonable "sickle-shaped" blanks and blank forging steps, and adopts special tooling and die dies to cooperate, thereby ensuring that the blanks can be completely placed in the mold cavity, and the blanks are well matched with the final forging mold, reducing the number of die forging fires and defects such as pinching and folding during the die forging process, and improving the original die forging forming process from multiple fires to one fire, effectively solving the problems of multiple die forging fires, small deformation, coarse grains of forgings, and unqualified performance, while greatly improving the low material utilization rate, the qualified rate of forgings, and the production efficiency. The method of the present invention is suitable for die forgings with a ratio of the sickle head to the rod section ≥ 3. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the forging of the first rough blank;

[0024] Figure 2 This is a schematic diagram of forging the second rough blank;

[0025] Figure 3 This is a schematic diagram of the forging of the third rough blank die;

[0026] Figure 4 This is the final schematic diagram;

[0027] Figure 5 This is the schematic diagram of the final waste type material arrangement;

[0028] Figure 6 It is a schematic diagram of a rocker arm forging of a certain type of machine in the embodiment. DETAILED DESCRIPTION

[0029] The present invention is a forging method for sickle-shaped die forgings, which is mainly applied to die forgings with a sickle head and a rod section ratio of ≥ 3. The method takes a different approach, designs blank production steps, and effectively cooperates with special tooling and special die, thereby reducing the difficulty of blank production for free forging under the existing technology, improving the consistency of blank size and quality stability, and effectively solving various quality problems generated during the die forging process, thereby improving product qualification rate and production efficiency.

[0030] like Figure 1-6 , a sickle-shaped die forging method, comprising:

[0031] A free forging hammer or a free forging press is used to upset and shape the bar material into a rectangular blank, the cross section of which is smaller than the cross section of the sickle head and larger than the cross section of the rod;

[0032] A free forging hammer or a free forging press is used, and a special tool is used to press a rectangular blank at a right angle to form an inclination to obtain a first blank. Then, according to the blank volume required for the head and the rod of the sickle blank, the material is divided along the length direction of the blank, and the rod is lengthened using a special tool to ensure the inclination at the transition to obtain a second blank.

[0033] The rod of the second blank is inserted into the lower die of the special mold and forged by a free forging hammer or a free forging press. For the blank with a simple upper end face shape of the sickle part, a pressure plate and a hammer anvil can be used in combination to upset and expand it to the final size of the head. For the blank with a complex upper end face shape of the sickle head, a pressure plate and a hammer anvil can be used in combination to upset and expand it to a size close to the final size of the head, and then the upper die of the mold can be used to cooperate and press it to the final size of the head. The sickle head part of the blank is upset and deformed, the cross-section is increased, and the head obtains a shape and size that meets the die forging requirements, thereby obtaining the third blank.

[0034] The third blank is taken out from the mold, and the rod portion is lengthened by a free forging hammer or a free forging press to obtain the final desired "sickle-shaped" blank.

[0035] The final rough shape is placed in a heating furnace for heating and heat preservation for a certain period of time. After it is taken out of the furnace, it is quickly transferred to the mold. According to the corresponding relationship between the mold and the rough shape head and stem, the outer contour of the rough shape is completely placed in the lower mold cavity. According to the depth of the sickle placed in the cavity, the height difference between the rough shape stem and the rough shape sickle is determined to make the rough shape swing smoothly without tilting. During forging, a counter-hammer or press is used to slowly press down for positioning, so that the rough shape moves down along the die slope, and then it is hammered or pressed down again to obtain the final die forging.

[0036] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be further described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0037] For "sickle-shaped" die forgings with a sickle head to stem cross-sectional ratio ≥ 3, on the one hand: design reasonable blank production steps based on the required blank size and shape.

[0038] Step 1:

[0039] The round bar is flattened as a whole along the radial direction and becomes a rectangular blank after forging;

[0040] Step 2:

[0041] The rectangular blank of step 1 is clamped by a manipulator, placed obliquely on a special tooling 1, and slowly pressed down to flatten one of the right angles of the rectangle to ensure the size b1 of the upper end surface of the rectangular blank, thereby obtaining the first blank;

[0042] The relationship between the angle θ3 in the special tool 1 and the angle θ2 in the first blank is θ2+θ3=180°, θ2 is generally taken between 135° and 180°, and the relationship between the size b1 reserved on the upper end surface and the width b of the rectangular blank is: b1≈1 / 3b;

[0043] Step 3:

[0044] According to the blank volume required for the head and the stem of the blank, a dividing tool is used to divide the blank, and then a special tool 2 is used to slowly press down and stretch the blank multiple times to ensure the inclined angle γ2, and obtain a second blank with a blank thickness of δ2, the second blank including the head and the stem;

[0045] The single pressing amount is 20-30mm, γ2=γ1±10°

[0046] Step 4:

[0047] Insert the rod of the second blank into the tire mold cavity, first use a pressing plate to expand the head blank along the slope of θ2, so that the lower mold of the tire mold is basically full, and the shape of the blank head is similar to the trend of the upper mold of the tire mold, and then use the upper mold of the tire mold to slowly press down and shape it, so that the shape of the blank head is completely consistent with the tire mold, take the blank out of the tire mold, and get the third blank.

[0048] The thickness dimension of the lower die opening of the tire mold δ=δ2+2*(10-30)mm, and the single-side gap between the thickness of the second blank δ and the thickness of the tire mold opening δ2 is 10-30mm.

[0049] Step 5:

[0050] The free forging equipment hammer anvil is used to lengthen and shape the final blank rod to obtain a "sickle-shaped" final blank;

[0051] The final height difference Δh between the head and the stem of the blank satisfies 2 / 3ΔH≤Δh<ΔH.

[0052] γ1=γ±10°, θ1=θ±10°

[0053] When the billet is stretched, the feeding amount of each hammer is 30-50mm, and the pressing amount of each hammer is 20-30mm. The second aspect:

[0054] The final rough shape is placed in a heating furnace and heated for a certain period of time. After it is taken out of the furnace, it is quickly transferred to the mold-lower model cavity. According to the corresponding relationship between the mold and the rough shape head and rod, the rough shape outer contour is completely placed in the lower model cavity. The height difference Δh between the rough shape head and rod corresponds to the height difference ΔH of the forging head and rod, among which 2 / 3ΔH≤Δh<ΔH. There is a height difference Δh1 between the rough shape rod and the lower model cavity in the height direction. In the design and actual production process, Δh1≤40mm is guaranteed. If Δh1 is too large, the rough shape will be too deflected when the material is swung, affecting the forming and deformation of the forging.

[0055] The die forging hammer or press slowly presses down, so that the rough blank is slowly pressed into the cavity along the die draft. Subsequent light tapping and slow pressing can effectively ensure that the rough blank flows into the cavity instead of forming a large amount of flash to obtain the final forging.

[0056] For β-forged or near-β-forged die forgings of titanium alloys such as TC18 and TC21, ensure that the deformation of each part of the die forging is 30%-60%;

[0057] For die forgings such as A-100 ultra-high strength steel and 300M alloy steel, ensure that the deformation of each part during die forging is ≥25%, and at the same time ensure that there are no obvious defects such as pinching and folding in each part of the forging during the die forging deformation process.

[0058] The preheating temperature of hammer, anvil and tool fixture is 200-300℃.

[0059] The mold preheating temperature is 250-350℃, and the mold lubrication is water-based graphite emulsion.

[0060] When using a press for forging, for titanium alloys such as TC18 and TC21, the pressing speed is ≤5mm / s; for A-100 ultra-high strength steel, 300M alloy steel, etc., the pressing speed is ≤10mm / s.

[0061] The special tooling, tire molds and mold materials used above are all 5CrNiMo.

[0062] Example:

[0063] A large rocker arm forging of a certain type of machine, made of A-100, has a structural feature of a "sickle-shaped" die forging, with a large head and a cross-section much larger than the rod section. The cross-section of the head and the cross-section of the rod are as high as 6. See the schematic diagram of the forging Figure 6, the thickness of the forging head is = 194mm, the thickness of the rod is = 50mm, the height difference is large, ΔH = 144mm, the angle between the outer bevel of the head and the rod is θ = 108°. The angle between the inner bevel of the head and the rod is γ = 148°

[0064] Design the blank and blank forging process, determine the various parameters in the forging process, and select the bar material of φ200×385mm.

[0065] The rough billet is forged on a forging press, heated to 1130℃ and kept warm. After coming out of the furnace, it is quickly transferred to the hammer anvil and forged into a rectangular billet with a billet size of 200mm (thickness)

[0066] ×230mm (width) ×265mm (length), use a manipulator to clamp the rectangular blank, place it on the special tool 1 at an angle, and slowly press it down to flatten one of the right angles of the rectangle. The upper end face of the rectangular blank is b1=80mm, and the angles θ3=25° and θ2=165° in the special tool 1 used. According to the blank volume required for the head and the rod of the blank, use the dividing tool to divide the material along the length direction, and then use the special tool 2 to slowly press down the elongated rod several times, with a single pressing amount of 20-30mm, to ensure that the inclined angle γ2=137°, and obtain a blank with a blank thickness of δ2=200mm;

[0067] The blank obtained above is returned to the furnace for heating at 1130℃ for a certain period of time. After being taken out of the furnace, the stem of the blank is quickly transferred and inserted into the tire mold cavity. The head blank is first expanded along the trend of the inclination θ2 using a pressing plate. The lower mold of the tire mold is basically filled during the upsetting process, and the shape of the blank head is similar to the trend of the upper mold of the tire mold. The upper mold of the tire mold is then used to slowly press down and shape the blank so that the shape of the blank head is completely consistent with the tire mold. The blank is taken out of the tire mold. The head size has met the final size requirements of the blank. The stem of the blank is lengthened and shaped to obtain a final "sickle-shaped" blank. The thickness dimension of the lower die opening of the tire mold is δ=225mm, the single-side gap between the blank thickness and the thickness of the tire mold opening is 12.5mm, the height difference between the head and the stem of the final blank is Δh=115mm, γ1=140°, θ1=109°, and when drawing, the feeding amount of each hammer is 30-50mm, and the pressing amount of each hammer is 20-30mm.

[0068] The final rough shape is placed in a heating furnace, heated to 1120℃ and kept warm for a certain period of time. After being taken out of the furnace, it is quickly transferred to the mold-lower model cavity, and the outer contour of the rough shape is completely placed in the lower model cavity. There is a height difference Δh1=20mm between the rough shape rod and the lower model cavity in the height direction. The die forging hammer or press is slowly pressed down to slowly press the rough shape into the cavity along the die ejection slope. The subsequent pressing speed is controlled to be 8mm / s to ensure that the rough shape flows into the cavity instead of forming a large amount of flash to obtain the final forging. During the die forging process, there are no obvious defects such as pinching and folding in various parts of the forging.

[0069] The forgings produced by the above method are formed by die forging and one-fire forming, the forgings are well filled, the forging qualification rate is 100%, the material utilization rate is high, and after the final physical and chemical testing, the forgings have uniform structure, the performance data meets the standard requirements, and have good stability.

[0070] The preheating temperature of hammer, anvil and tool fixture is 200-300℃.

[0071] The mold preheating temperature is 250-350℃, and the mold lubrication is water-based graphite emulsion.

[0072] The special tooling, tire molds and mold materials used above are all 5CrNiMo.

Claims

1. A forging method for a sickle-shaped die forging, wherein the cross section of the sickle head is larger than the cross section of the rod, characterized in that: The method comprises: Step 1: Use a free forging hammer or a free forging press to upset and shape the bar material into a rectangular blank, wherein the cross section of the rectangular blank is smaller than the cross section of the sickle head and larger than the cross section of the rod; Step 2: Use a free forging hammer or a free forging press to press the rectangular blank at a right angle to form an inclined surface to obtain a first blank; then divide the first blank along the length direction according to the blank volume required for the sickle blank head and the rod, and then lengthen the rod position and ensure that the transition is an inclined surface to obtain a second blank; Step 3: insert the rod of the second blank into the lower die of the tire mold, and forge it with a free forging hammer or a free forging press. For the blank with a simple upper end face shape of the sickle head, use a pressing plate and a hammer anvil to upset and expand it to the final size of the head. For the blank with a complex upper end face shape of the sickle head, first use a pressing plate and a hammer anvil to upset and expand the second blank, and then use the upper die of the tire mold to press it to the final size of the head to obtain a third blank; Step 4: Take the third blank out of the mold, use a free forging hammer or a free forging press to lengthen the rod portion, and obtain the final desired "sickle-shaped" blank; Step 5: Place the "sickle-shaped" rough mold into the heating furnace for heating and heat preservation for a certain period of time. After it comes out of the furnace, quickly transfer it to the final forging die. During forging, use a counter-hammer or press to slowly press down for positioning, so that the rough mold moves down along the die slope, and then hammer or press down to obtain the final die forging.

2. The method according to claim 1, characterized in that In step 2, the angle θ2 between the inclined surface pressed in the first blank and the upper end surface is 135° to 180°.

3. The method according to claim 2, characterized in that In step 2, the relationship between the width b1 reserved on the upper end surface of the first blank and the width b of the rectangular blank is: b1 = 1 / 3b.

4. The method according to claim 3, characterized in that In step 2, the angle between the head and the stem of the second blank satisfies γ2: γ2 = γ1 ± 10°, wherein γ1 is the angle between the head and the stem of the final desired "sickle-shaped" blank.

5. The method according to claim 4, characterized in that In step 2, the single pressing amount during the pulling process is 20-30 mm.

6. The method according to claim 5, characterized in that In step three, the single-side gap between the second blank thickness δ and the tire mold opening thickness δ2 is 10-30 mm.

7. The method according to claim 6, characterized in that In step 4, the final required height difference Δh between the head and the rod of the "sickle-shaped" rough forging satisfies: 2 / 3ΔH≤Δh<ΔH, γ1=γ±10°, θ1=θ±10°, where γ is the angle between the head and the rod of the forging, and γ1 is the final required angle between the head and the rod of the "sickle-shaped" rough forging.

8. The method according to claim 7, characterized in that In step 4, when the billet is stretched, the feeding amount of each hammer is 30-50mm, and the pressing amount of each hammer is 20-30mm.

9. The method according to claim 7, characterized in that: In step 5, when using a press for forging, for TC18 and TC21 titanium alloys, the pressing speed is ≤5 mm / s; for A-100 ultra-high strength steel and 300M alloy steel, the pressing speed is ≤10 mm / s.

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