A method for forming a titanium alloy die forging having a profile distributed in a perpendicular plane

Abstract

The present application belongs to the field of metal material forging hot working, and relates to a forming method of a special-shaped titanium alloy die forging with a shape in vertical plane distribution. The free forging blank and die forging of the present application adopt multi-reversing forging (both pre-forging and final forging adopt variable forging direction), can realize production of a special-shaped component die forging with high cross section size in three directions (ST), LT and L), large cross section size difference, complex shape and shape similar to two large plates in vertical distribution under the condition of limited bar specifications.

Description

Technical Field

[0001] This invention belongs to the field of hot working of metal materials forging, and relates to a method for forming irregularly shaped titanium alloy forgings with vertically distributed shapes. Background Technology

[0002] With the continuous improvement of forging equipment capabilities, aircraft structural components in the aerospace field are rapidly developing towards larger dimensions, more complex integral structures, and superior comprehensive mechanical properties. The main production process for aerospace titanium alloy parts involves forging titanium alloy bars through multiple heats using forging equipment to produce titanium alloy blank forgings. These blank forgings are then machined into titanium alloy parts with unique structures using CNC machine tools. Previously, titanium alloy parts were typically designed with simplified blank forgings, resulting in relatively simple structures that were easy to hot-forge. These simplified blank forgings were then machined into parts and welded together. Therefore, traditional titanium alloy blank forgings had relatively simple structures and smaller dimensions, resulting in lower requirements for forging equipment, processes, and production difficulty. However, aircraft structural components assembled by welding do not have the advantages of integral structural components in terms of load-bearing capacity and aircraft application. Integral structural components not only eliminate the need for welding but also offer superior and more stable performance during use, and are less prone to damage. With the continuous upgrading of domestic extra-large forging equipment and the continuous improvement of equipment capabilities, the design of aircraft structural components forging blanks has gradually evolved from the original assembly of multiple parts by welding to the design of integral forging blanks. This has increased the outline dimensions, overall weight, and structural complexity of the forging blanks. Forging blanks are trending towards complex structures with irregular shapes, multiple cross sections, and variable cross sections. At the same time, this has placed higher demands on many aspects of the forging hot working industry, such as equipment tonnage, mold design, and forging process forming methods.

[0003] The present invention relates to an irregularly shaped titanium alloy forging with a vertically distributed shape, the shape of which is as follows: Figure 5 As shown, the titanium alloy blank forging weighs 270 kg. The maximum cross-sectional dimension of the blank forging in the longitudinal (L-direction), transverse (LT-direction), and height (ST-direction) directions is ≥550 mm, and there is a variable cross-section on the same cross-section. The ratio of the maximum dimension to the minimum dimension is 6.9 (H). 大 / H 小 (≥6.9). It is extremely difficult to produce this blank forging using traditional upsetting and drawing processes. Summary of the Invention

[0004] Objective of the invention: To provide a method for forming irregularly shaped titanium alloy forgings with vertically distributed shapes, solving the following problems: when the size of round bar stock is limited, forging titanium alloy forgings with relatively large dimensions in the longitudinal (L), transverse (LT), and vertical (ST) directions; at the same time, it should also satisfy the requirement that the forging process is completely filled while the ratio of the maximum to the minimum dimension on the transverse (LT) section is relatively large.

[0005] Technical solution:

[0006] A method for forming irregularly shaped titanium alloy forgings with vertically distributed shapes, comprising:

[0007] Step 1: Chamfer and face the bar stock;

[0008] Step 2: Upsetting the bar stock obtained in Step 1 to obtain a round billet: The bar stock obtained in Step 1 is subjected to N upsetting deformations along the axial direction, so that the cross-sectional dimension of the upset round bar stock is greater than or equal to the cross-sectional dimension of the final blank forging, where N is an integer greater than or equal to 2.

[0009] Step 3: Square the round billet obtained in Step 2 and divide and elongate it to obtain a forging billet: Forge the upset round billet into a square billet, and feed the square billet into the free forging hammer along the transverse LT direction. Locally elongate the LT direction dimension of the square billet so that the forging billet forms a step on the upper and lower end faces of the high direction ST along the transverse LT direction, and obtain a large cross section and a small cross section.

[0010] Step 4: Pre-forging to obtain a pre-forged part: The cavity of the pre-forging die includes a first cavity and a second cavity. The first cavity corresponds to the high plane of the final forging, and the second cavity corresponds to the transverse plane of the final forging. The outline dimension of the first cavity is larger than the outline dimension of the high plane of the final forging, and the height dimension of the first cavity is smaller than the thickness of the high plane of the final forging. The thickness of the second cavity is larger than the thickness of the transverse plane of the final forging, the width of the second cavity is smaller than the width of the transverse plane of the final forging, and the height of the second cavity is smaller than the transverse dimension of the longer transverse plane on both sides of the high plane of the final forging.

[0011] Reversed forging: The small section of the forging billet is inserted into the pre-forging lower mold cavity along the LT direction, and the upper mold of the pre-forging die is pressed up and down using a flat die;

[0012] Step 5: Final forging: Reversed forging: The pre-forging part is rotated 90°, and the ST direction of the forging billet after being fully widened after pre-forging is placed into the cavity of the final forging die for final forging. The final forging part is completely filled.

[0013] Furthermore, in step 1, the surface finish of the bar stock is Ra3.2-Ra6.3, and the end face chamfer is R5-R10.

[0014] Furthermore, in step 2, the cross-sectional dimension of the upset round bar is made greater than or equal to the cross-sectional dimension of the final blank forging, specifically as follows:

[0015] The cross-sectional area of ​​the upset round bar is equal to the cross-sectional area of ​​the final blank forging (LT×ST), and the longitudinal cross-sectional area of ​​the round bar is equal to the longitudinal cross-sectional area of ​​the final blank forging (L×ST). L corresponds to the axial direction of the bar, and LT and ST correspond to the radial direction of the bar.

[0016] Furthermore, the upper die of the pre-forging die uses a flat die for upper and lower pressing, specifically including:

[0017] Multi-stage pressing is adopted, with deformation amount ≤35% per stage and upper die pressing speed ≤5mm per stage.

[0018] Furthermore, the ST direction of the forging billet, after being fully widened during pre-forging, is placed into the final forging die cavity as the height direction for final forging, specifically including:

[0019] Multi-stage pressing is adopted, with deformation amount ≤35% per stage and upper die pressing speed ≤5mm per stage.

[0020] Furthermore, the volume of the second cavity of the pre-forging die is greater than the volume of the longer transverse surfaces on both sides of the high plane of the final forging.

[0021] Furthermore, step 2 is specifically completed through 2-3 firings.

[0022] Furthermore, the length of the small cross-section of the forging billet is greater than the height of the second cavity of the pre-forging die.

[0023] Furthermore, after the pre-forged part is placed into the final forging die, there is a predetermined distance between the upper and lower dies.

[0024] Beneficial effects:

[0025] The free forging billet and die forging proposed in this invention employ multiple reversing forging processes (both pre-forging and final forging involve changing the forging direction). This enables the production of irregularly shaped die forgings with large cross-sectional dimensions in the three directions (ST, LT, and L) and significant differences in cross-sectional dimensions, even with limited bar stock specifications. These forgings resemble two large, vertically distributed flat plates. This solves the technical challenges of forging such complex components. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the billet being drawn and stretched.

[0027] Figure 2 This is a schematic diagram of pre-forging.

[0028] Figure 3 This is a schematic diagram of a pre-forged part;

[0029] Figure 4 This is a schematic diagram of the final forging process;

[0030] Figure 5 This is a schematic diagram of the final forging. Detailed Implementation

[0031] The irregularly shaped titanium alloy forging includes a transverse surface and a vertical surface, which are perpendicular to each other. One side of the transverse surface has an irregularly shaped platform.

[0032] This invention is achieved through the following forging process, the specific process and key technical features of which are as follows:

[0033] Step 1: Machine the end face and chamfer

[0034] The titanium alloy round bars are required to be machined and have rounded corners, with a surface finish of Ra3.2-Ra6.3 and end face chamfers of R5-R10. The surface quality must be checked to eliminate potential cracking hazards.

[0035] Step 2: Upsetting to obtain a round blank

[0036] The titanium alloy round bar is upset 2-3 times along the axial direction so that the cross-sectional dimensions of the upset round bar are equal to the cross-sectional dimensions of the final blank forging: that is, the cross-sectional area (circular cross-sectional area) of the upset round bar is equal to the cross-sectional area (LT×ST) of the final blank forging, and the longitudinal cross-sectional area (axial cross-sectional area) of the round bar is equal to the longitudinal cross-sectional area (L×ST) of the final blank forging; L corresponds to the axial direction of the bar, and LT and ST correspond to the radial direction of the bar.

[0037] The key technical feature of this step is that the bar stock is upset axially to obtain the large cross-sectional area required for the blank forging.

[0038] Step 3: Squaring the round blank and dividing and elongating it to obtain the forging blank.

[0039] The upset round billet is forged into a square billet, and the square billet is fed into the free forging hammer along the transverse (LT) direction. The LT direction dimension of the square billet is locally elongated, so that the forging billet forms a step on the upper and lower end faces of the height (ST) direction along the transverse (LT) direction, thus obtaining a large cross section and a small cross section.

[0040] The key technical features of this step are: First, strictly controlling the length and thickness of the small cross-section of the forging billet. The thickness of the small cross-section is slightly smaller than the width of the small cross-section within the pre-forging mold cavity (approximately 5mm allowance on one side), allowing the small cross-section to be smoothly placed into the lower pre-forging mold cavity; the length of the small cross-section is slightly greater than the height of the small cross-section within the lower pre-forging mold cavity (approximately 5-10mm larger), ensuring that the small cross-section undergoes upsetting deformation within the lower pre-forging mold cavity during pre-forging, rather than being extruded, which is beneficial for upsetting and filling the bottom of the lower pre-forging mold cavity. Second, strictly controlling the length of the large cross-section. This mainly ensures the volume of the large cross-section of the forging billet, ensuring that after upsetting during pre-forging, the large cross-section obtains the maximum height (ST) dimension and cross-sectional area required for final forging, allowing the large cross-section to be completely filled during pre-forging.

[0041] Step 4: Pre-forging (reversing forging) to obtain pre-forged parts

[0042] The cavity of the pre-forging die includes a first cavity and a second cavity, wherein the first cavity corresponds to the height surface of the final forging and the second cavity corresponds to the transverse surface of the final forging. The outline dimension of the first cavity is larger than the outline dimension of the height surface of the final forging, and the height dimension of the first cavity is smaller than the thickness of the height surface of the final forging.

[0043] The thickness of the second cavity is greater than the thickness of the transverse surface of the final forging; the width of the second cavity is less than the width of the transverse surface of the final forging; the height of the second cavity is less than the transverse dimension of the longer transverse surface on both sides of the high plane of the final forging; and the volume of the second cavity is greater than the volume of the longer transverse surface on both sides of the high plane of the final forging.

[0044] Reversed forging: The small section of the forging billet is inserted into the pre-forging lower mold cavity along the LT direction (i.e., LT is the height direction). The upper die of the pre-forging mold uses a flat die for pressing from top to bottom. This achieves the following: the small section is fastened and locally upset in the pre-forging cavity, while the large section of the forging billet is upset as a whole in the upper part of the cavity and fully widened along the horizontal direction (ST). The forging billet obtains the maximum size and cross-sectional area in the ST direction. In this step, the large section of the forging billet deforms drastically during the upper flat die pressing. Multiple pressing can be used, with the deformation amount per pressing ≤35% and the upper die pressing speed per pressing ≤5mm, to avoid the large thermal effect caused by the severe deformation of the alloy.

[0045] The key technical features of this step are: first, reversible forging; second, reasonable design of the pre-forging die and strict control of the maximum dimension and cross-sectional area of ​​the ST direction of the pre-forging part, as well as the volume of the small cross-sectional section of the pre-forging part. The purpose of controlling the maximum dimension of the ST direction is to achieve upsetting deformation rather than reverse extrusion filling in the cavity of the final forging die during the next step, final forging (step 5), which is beneficial to the good filling of the forging part during final forging; the purpose of controlling the volume of the small cross-sectional section is to fill the thin web of the final blank forging part in the cavity of the final forging die during the next step, final forging (step 5).

[0046] Step 5: Final Forging (Reversed Forging)

[0047] Reversed forging: The pre-forging part is flipped 90°, that is, the ST direction of the forging blank after the pre-forging is fully widened is placed into the cavity of the final forging die as the height direction. The maximum dimension of the ST direction of the forging blank is achieved by upsetting deformation in the cavity of the final forging die through the pressing of the upper and lower dies instead of reverse extrusion filling, and the final forging is completely filled.

[0048] In this step, when pressing with the upper final forging die, multiple pressing is adopted, with the deformation amount per pressing ≤35% and the pressing speed of the upper die per pressing ≤5mm, to avoid the alloy from undergoing severe deformation and generating a large thermal effect.

[0049] The key technical features of this step are: first, reversible forging; second, the maximum dimension of the forging billet in the ST direction is upset in the final forging cavity instead of being filled by reverse extrusion, which is beneficial to the good filling of the die forging during the final forging.

[0050] The technical solution of the present invention will be further described in detail below with reference to the embodiments:

[0051] The present invention describes a large titanium alloy die forging ( Figure 5 The forging has an outline dimension of 550mm × 560mm × 665mm (ST × LT × L) and a shape resembling two large, vertically distributed flat plates. The minimum web size is only 80mm. The overall dimensional differences are significant, and the forging structure is complex, making die forging extremely difficult. Forging material: TA15; forging weight: 270kg.

[0052] The forging process is detailed below:

[0053] Step 1: Machine roughen the two ends of the φ300×L1 bar stock to ≤Ra3.2 and chamfer the edges to R10; then perform a surface quality inspection.

[0054] Step 2: Upsetting: The round bar material with a specification of φ300×~990 is upset and rounded to φ380×~610 in the first heat, and then upset and rounded to φ450×~435 in the second heat;

[0055] Step 3: Squaring and drawing: Forge the billet φ450×~435(L) to 330(ST)×420×500(L), then draw it to length. Figure 1 For dimensions and forging process, see [link / details]. Figure 1 ;

[0056] Step 4: Pre-forging: Reversing forging: ... Figure 1 The resulting small cross-sectional segment of the forging billet is inserted into the pre-forging mold cavity along the LT direction (i.e., the LT of the forging billet is the pressing direction), and the upper pre-forging die is a flat die, such as... Figure 2 As shown, during pressing, the following can be achieved: the small section of the forging billet is fastened in the pre-forging mold cavity for local upsetting deformation, while the large section of the forging billet is upset in the upper part of the cavity, fully widening along the horizontal direction (ST direction) to obtain a large-size plane in the ST direction. After pre-forging, the following is obtained: Figure 3 The pre-forged part shown, Figure 3 The ST-axis large-size planar profile shown is 680(ST) × 590(L). Based on the deformation requirements per heat treatment of the titanium alloy, step 4 in this embodiment can be completed in 2-3 heat treatments.

[0057] Step 5: Final Forging: Reversing Forging: Rotate the pre-forging part by 90°, that is, use the ST direction of the pre-forging part as the pressing direction, such as... Figure 4As shown, the pre-forging part is placed into the cavity of the final forging die. During the pressing of the upper and lower dies, local upsetting in the ST direction and full widening in the LT and L directions are achieved, resulting in the final forging part. Figure 5 .

Claims

1. A method for forming irregularly shaped titanium alloy forgings with vertically distributed shapes, characterized in that, include: Step 1: Chamfer and face the bar stock; Step 2: Upsetting to obtain a round billet: The bar obtained in Step 1 is upset N times along the axial direction to make the cross-sectional dimension of the upset round bar greater than or equal to the cross-sectional dimension of the final blank forging. Specifically, the cross-sectional area of ​​the upset round bar is equal to the cross-sectional area of ​​the final blank forging: the cross-sectional area of ​​the blank forging is LT × ST (transverse direction), and the longitudinal cross-sectional area of ​​the upset round bar is equal to L × ST (longitudinal direction), where L corresponds to the axial direction of the bar, and N is an integer greater than or equal to 2. Step 3: Square and divide the material to obtain the forging billet: Forge the upset round billet into a square billet, and feed the square billet into the free forging hammer along the transverse LT direction. Locally lengthen the LT direction dimension of the square billet, so that the forging billet forms a step on the upper and lower end faces of the high direction ST along the transverse LT direction, and obtain a large cross section and a small cross section. Step 4: Pre-forging to obtain a pre-forged part: The cavity of the pre-forging die includes two cavities, where the first cavity corresponds to the height surface of the final forging and the second cavity corresponds to the transverse surface of the final forging. The outline dimension of the first cavity is larger than the outline dimension of the height surface of the final forging, and the height dimension of the first cavity is smaller than the thickness of the height surface of the final forging. The thickness of the second cavity is larger than the thickness of the transverse surface of the final forging, the width of the second cavity is smaller than the width of the transverse surface of the final forging, and the height of the second cavity is smaller than the transverse dimension of the longer transverse surface of the final forging located on both sides of the height surface. Reversed forging: The small section of the forging billet is inserted into the pre-forging lower mold cavity along the LT direction, and the upper mold of the pre-forging die is pressed up and down using a flat die; Step 5: Final forging: Reversed forging: The pre-forging part is rotated 90°, and the ST direction of the forging blank after being fully widened after pre-forging is placed into the cavity of the final forging mold for final forging. Finally, the blank forging is completely filled.

2. The method for forming irregularly shaped titanium alloy forgings with a vertically distributed shape according to claim 1, characterized in that, In step 1, the surface finish of the bar stock is Ra3.2-Ra6.3, and the end face chamfer is R5-R10.

3. The method for forming irregularly shaped titanium alloy forgings with a vertically distributed shape according to claim 1, characterized in that, The upper die of the pre-forging die uses a flat die for pressing from both sides, specifically including: Multi-stage pressing is adopted, with deformation amount ≤35% per stage and upper die pressing speed ≤5mm per stage.

4. The method for forming irregularly shaped titanium alloy forgings with a vertically distributed shape according to claim 1, characterized in that, The ST direction of the forging billet, after being fully widened during pre-forging, is used as the height direction and placed into the cavity of the final forging die for final forging. Specifically, this includes: Multi-stage pressing is adopted, with deformation amount ≤35% per stage and upper die pressing speed ≤5mm per stage.

5. The method for forming irregularly shaped titanium alloy forgings with a vertically distributed shape according to claim 1, characterized in that, The volume of the second cavity of the pre-forging die is greater than the volume of the longer transverse surfaces on both sides of the high plane of the final forging.

6. The method for forming irregularly shaped titanium alloy forgings with a vertically distributed shape according to claim 1, characterized in that, Step 2 is completed by firing 2-3 times.

7. The method for forming irregularly shaped titanium alloy forgings with a vertically distributed shape according to claim 1, characterized in that, The length of the small cross-section of the forging billet is greater than the height of the second cavity of the pre-forging die.

8. The method for forming irregularly shaped titanium alloy forgings with a vertically distributed shape according to claim 1, characterized in that, After the pre-forged part is placed into the final forging die, there is a predetermined distance between the upper and lower dies.

Images