Forging method for large-size M-shaped titanium alloy whole-frame die forging

Abstract

The invention belongs to the field of material hot working, and relates to a forging method for a large-size M-shaped titanium alloy whole-frame die forging. The method comprises the steps that forge piece design is conducted according to the feature structure of a part, after a bar is made into a long-strip forging stock, a rough mold is prepared in the mode that two cutting and two bending are conducted alternately, the rough mold is put into a mold cavity to be subjected to die forging, and preparation of ya through the forge piece is completed through heat treatment.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of material hot working, and relates to a forging method of a large-size M-shaped titanium alloy whole-frame die forging. BACKGROUND

[0002] At present, the application range of titanium alloy in the fields of aerospace, weapon equipment and the like is gradually expanded, and each institute and main machine factory puts forward more stringent requirements for improving the comprehensive mechanical properties of titanium alloy forgings and reducing the manufacturing cost of titanium alloy parts. Meanwhile, in the face of the service requirements of large bearing, high precision and low cost of aviation equipment, aircraft parts tend to be integrated and lightweight. Based on the above status, how to improve the production efficiency and material utilization of forgings on the premise of ensuring the comprehensive mechanical properties of large-size titanium alloy whole-frame forgings, each major aviation forging supplier in China is facing severe challenges.

[0003] In recent years, the large-size titanium alloy whole-frame forgings mainly include an X-shaped frame, a K-shaped frame and an M-shaped frame. For such complex configuration whole-frame forgings, the blank is generally cut by cutting plate material and then subjected to die forging production. This method has the following problems: 1. Low material utilization rate, the cut part of the plate material occupies a large area and cannot be used for the production of forgings again; 2. The blank streamline cannot be distributed along the geometric shape of the forging, and the organization and performance of the forging cannot be guaranteed; 3. The cutting adaptability is poor, and the material organization is easily damaged. The cutting length is large, the cutting rate is low, and the cutting time is long by using the line cutting method. The plate material with large thickness cannot be cut by using the water cutting method. The material organization at the cutting position is easily damaged at high temperature when using the flame cutting method, which weakens the performance of the forging. SUMMARY

[0004] The application provides a forging method of a large-size M-shaped titanium alloy whole-frame die forging, which can significantly improve the material utilization rate of the large-size M-shaped titanium alloy whole-frame die forging, greatly reduce the production cost, ensure that the blank streamline direction is consistent with the geometric shape of the forging, guarantee the organization and performance of the forging, and improve the product qualification rate.

[0005] TECHNICAL SCHEME The application provides a forging method of a large-size M-shaped titanium alloy whole-frame die forging, which comprises the following steps: According to the characteristics of the part, a long strip forging blank is prepared from a bar, and a blank is prepared by alternately performing two cutting and two bending, the blank is placed in a die cavity for die forging, and the forging is prepared through heat treatment.

[0006] Further, the bar is prepared into a long strip forging blank, which comprises the following steps: The bar is selected as the raw material, and the selection principle of the bar specification is that the cross-sectional area of the bar is 1.1-1.2 times the maximum cross-sectional area of the rough shape of the forged piece. The bar is preliminarily forged into a long strip-shaped blank by free forging.

[0007] Further, the rough shape is prepared by alternately performing two cutting and two bending, comprising: The leg ear of the forged piece is separated on the long strip-shaped blank, the first cutting is performed on the tail of the blank in the length direction by wire cutting, the cutting is performed to the first separation line to form two arms of the blank, and then the first bending is performed to make the two arms of the blank open to a specific angle; The leg of the forged piece is separated on the long strip-shaped blank, the second cutting is performed from the intersection of the two arms in the length direction by wire cutting, the cutting is performed to the second separation line, and then the second bending is performed to make the two arms of the blank further open to a specific angle along the shape of the forged piece.

[0008] Further, the method further comprises: According to the part feature structure, the design allowance is changed, and the design allowance of the forged piece is increased at the risk position.

[0009] Further, the heating temperature of the rough shape during die forging is Tβ-30℃-Tβ-40℃, and the deformation amount of each fire is 25%-30%.

[0010] Further, the method further comprises: Before the bending after the twice cutting, the punch is used to punch the two arms of the blank after cutting to a certain angle from the intersection position of the two arms, so as to facilitate the bending hammer.

[0011] Further, the heating temperature of the die is specifically 250℃-350℃.

[0012] Further, the method further comprises: The forged piece is subjected to annealing heat treatment: The first annealing is performed at a heating temperature of 850℃, and the cooling mode is air cooling; The stress relief annealing is performed at a heating temperature of 600-620℃, and the cooling mode is air cooling.

[0013] Beneficial effects: The manufacturing technology of the large-size M-shaped titanium alloy whole frame forged piece is provided, so that the material utilization rate of the large-size M-shaped whole frame forged piece is significantly improved, the production cost is reduced, the flow line direction of the blank is consistent with the geometric shape of the forged piece, the organization and performance of the forged piece are ensured, and the product qualification rate is improved. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The schematic diagram of the die forging piece is shown.

[0015] Figure 2A schematic view of an example intermediate forging.

[0016] Figure 3 A schematic view of an example first parting.

[0017] Figure 4 A schematic view of an example first bending.

[0018] Figure 5 A schematic view of an example second parting.

[0019] Figure 6 A schematic view of an example second bending. DETAILED DESCRIPTION

[0020] A forging method for a large-size M-shaped titanium alloy whole frame die forging is proposed, and the large-size M-shaped titanium alloy whole frame die forging is prepared by the following steps: 1) Design the forging according to the part shape, and design the forging by using the variable allowance design idea; 2) The bar stock is forged into a long strip-shaped forging blank by free forging; 3) The forging blank of step 2 is first parted from the middle by wire cutting, and is bent and formed; 4) The forging blank of step 3 is secondly parted from the middle by wire cutting, and is bent and formed again; 5) The blank prepared in step 4 is put into a final forging die for die forging to prepare the forging; 6) The forging prepared in step 5 is subjected to annealing heat treatment.

[0021] The large-size M-shaped titanium alloy whole frame forging blank can be quickly prepared by the method of twice parting and bending alternately, and is formed by one-step die forging by using a press, so that compared with the traditional whole frame forging manufacturing technology, the process route is simple, the operation is convenient, the material utilization rate can be greatly improved, and the blank forming fire times are reduced.

[0022] Specifically, the following steps are included: Step 1: Design the forging according to the part shape structure, and select the maximum projection area region in the thickness direction as the parting surface to facilitate the forging forming.

[0023] In particular, the forging allowance, draft angle and excess fillet are designed according to the part structure characteristics. When designing, the forming risk parts such as high bosses and thin narrow ribs are identified, the design allowance is increased, and the die forging design and optimization are carried out.

[0024] Step 2: Select a bar as the raw material, and the bar specification selection principle is that the cross-sectional area of the bar is 1.1~1.2 times the maximum cross-sectional area of the forging blank, and the bar is preliminarily forged into a long strip-shaped plate blank by free forging.

[0025] Preferably, the post-forging angle should be adjusted in time to prevent the die forging from being damaged.

[0026] Step 3: The blank prepared in Step 2 is first cut by wire cutting, and then is first bent to open the two arms of the blank to a specific angle.

[0027] In particular, the cutting depth should be strictly controlled to ensure sufficient material left; Step 4: The blank prepared in Step 3 is second cut by wire cutting, and then is second bent to further open the two arms of the blank to a specific angle along the shape of the forging.

[0028] The purpose of the two cutting and bending in Step 3 and Step 4 is to make the metal flow line of the blank consistent with the shape of the forging, and to ensure the organization and performance of the forging.

[0029] Preferably, before bending in Step 3 and Step 4, a punch should be used to open the two arms of the blank cut at the root to a certain angle, which is convenient for the bending hammer; Preferably, during the bending of the two arms in Step 3 and Step 4, the blank on the side of the rear hammer should be covered with high-temperature cotton after being discharged from the furnace to prevent the blank from cooling too quickly and causing cracking during bending; Preferably, a special template should be used for comparison between each bending to control the consistency of the shape of the two arms with the corresponding parts of the forging; In particular, a V-shaped tool should be used to assist bending when the hammer is bent, and the hammer should be slowly lowered along the length direction of the two arms to open the two arms to a specific arc.

[0030] Step 5: The rough shape prepared in Step 4 is put into a final forging die to perform die forging to prepare the forging.

[0031] Further, the heating temperature of the blank in Step 1 to Step 5 is T β -30℃ ~ T β -40℃; Further, the heating temperature of the die in Step 1 to Step 5 is specifically 250℃~350℃; Further, when die forging is performed in Step 5, insulation cotton should be wrapped on the surface of the rough shape to reduce the temperature loss during the transfer process; at the same time, a lubricant should be sprayed in the die cavity to reduce the metal flow resistance, which is beneficial to the die forging; Further, the deformation amount of each fire in Step 5 when die forging is 25%~30%.

[0032] Step 6: The forging prepared in Step 5 is subjected to annealing heat treatment.

[0033] Further, Step 6 includes: once annealing, the heating temperature is 850℃, and the cooling method is air cooling.

[0034] Furthermore, step 6 also includes: stress-relief annealing, with a heating temperature of 600~620℃ and air cooling.

[0035] Preferably, the uniformity of the electric furnace is ±10℃, and the transfer time of the forgings after exiting the furnace is ≤2min; Preferably, the holding time for the two annealing processes of the forging is determined according to its effective thickness, and the holding coefficient is 0.5 to 0.8 min / mm; Preferably, when loading forgings into the furnace, they should be placed on a flat loading rack, arranged in a single layer and leveled with pads to prevent deformation that could lead to uneven machining allowances. When loading into the furnace, the forgings should be placed within the effective heating zone of the furnace.

[0036] Significance of the invention This invention proposes a manufacturing technology for large-size M-shaped titanium alloy frame forgings, which significantly improves the material utilization rate of large-size M-shaped frame forgings and reduces production costs. At the same time, it can also ensure that the flow line direction of the billet is consistent with the geometric shape of the forging, thus guaranteeing the microstructure and properties of the forging and improving the product qualification rate.

[0037] Example The following detailed description of each step of the present invention is provided through specific implementation examples.

[0038] A certain type of aircraft TA15 titanium alloy large-size M-shaped integral frame forging (see...) Figure 1 The forging has dimensions of 3663×1449×232 mm and a maximum projected area of ​​1.8 m². 2 The raw material has a phase transformation point of 992℃, and forging is carried out using the method described in this invention. The specific steps are as follows: Step 1: Design the forging based on the shape characteristics of the part, and select the area with the largest projected area in the thickness direction as the parting surface.

[0039] Step 2: Select the bar specifications based on the maximum cross-sectional area of ​​the intermediate billet. The maximum cross-sectional area of ​​the intermediate billet is 0.09 m². 2 Φ400 gauge bars should be selected as raw materials. The bars should then be forged in multiple passes. Figure 2 For the elongated slabs shown, the edges and bulges of the slabs should be tidied up between each firing cycle to prevent damage.

[0040] Step 3: The blank obtained in Step 2 is first cut using wire cutting. The cutting positions are as follows: Figure 3 As shown, the billet is then bent and shaped using free forging, causing the two arms of the billet to open at a specific angle, forming a shape as shown. Figure 4 The wasteland shown.

[0041] Step 4: After the rough shape obtained in Step 3 is divided, drawn, and wire-cut, it is then cut a second time. The cutting positions are as follows: Figure 5As shown, then further bending forming in the way of free forging, forming a rough shape as shown in Figure 6.

[0042] Step 5: Put the rough shape prepared in step 4 in the mold cavity for die forging. The mold heating temperature is 300°C, the rough shape is wrapped with heat preservation cotton during die forging, and a lubricant is sprayed in the mold cavity.

[0043] Step 6: Annealing heat treatment is performed on the forged piece prepared in step 5. The first annealing heating temperature is 850°C, the holding time is 240 min, and the cooling mode is air cooling; the stress relief annealing heating temperature is 600-620°C, the holding time is 180 min, and the cooling mode is air cooling.

Claims

1. A method of forging a large size M-shaped titanium alloy monoblock die forging, characterized by, The method comprises the following steps: According to the characteristics of the parts, the bar is forged into a long strip blank, and then the rough shape is prepared by alternately cutting and bending twice, and the rough shape is placed in the mold cavity for die forging, and the forging is completed by heat treatment.

2. The method of claim 1, wherein, The bar is forged into a long strip blank, comprising: Selecting a bar as the raw material, and the selection principle of the bar specification is that the cross-sectional area of the bar is 1.1~1.2 times the maximum cross-sectional area of the rough shape of the forging; The bar is preliminarily forged into a long strip-shaped plate blank by free forging.

3. The method of claim 2, wherein, The rough shape is prepared by alternately cutting and bending twice, comprising: The leg ear of the forging is separated on the long strip-shaped plate blank, the tail of the plate blank is first cut in the length direction by wire cutting, and the cut is divided into a first separation line to form two arms of the blank, and then the first bending is performed to open the two arms of the blank to a specific angle; The leg of the forging is separated on the long strip-shaped plate blank, the second cutting is performed in the length direction from the intersection of the two arms by wire cutting, and the cut is divided into a second separation line, and then the second bending is performed to further open the two arms of the blank to a specific angle along the shape of the forging.

4. The method of claim 3, wherein, The method further comprises: According to the characteristics of the parts, the variable allowance design is performed, and the design allowance of the forging is increased at the risk position.

5. The method of claim 3, wherein, The heating temperature of the rough shape during die forging is Tβ-30℃ ~ Tβ-40℃, and the deformation amount of each fire is 25%~30%.

6. The method of claim 3, wherein, The method further comprises: Before bending after twice cutting, the punch is used to punch the two arms of the cut blank apart by a certain angle from the intersection position of the two arms, so as to facilitate the bending of the hammer.

7. The method of claim 5, wherein, The heating temperature of the mold is specifically 250℃~350℃.

8. The method of claim 1, wherein, The method further comprises: Annealing heat treatment is performed on the forging: Primary annealing, heating temperature is 850℃, and the cooling method is air cooling; Stress relief annealing, heating temperature is 600~620℃, and the cooling method is air cooling.

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