A multi-cavity superplastic forming mold for small-sized titanium alloy components and its forming method

Abstract

This invention discloses a multi-cavity superplastic forming mold for small-sized titanium alloy components and its forming method. The forming mold consists of an upper mold cover, a stripper plate, forming molds, a base, and positioning pins. Multiple forming molds are located on the base and are engaged with the base positioning grooves by positioning pins. The upper mold cover, stripper plate, and base are positioned by their positioning holes and positioning pins. The mold also has a set of air blowing cooling fixtures to assist in the removal of difficult-to-demold structural parts from the furnace. This invention achieves efficient product forming by optimizing the mold structure and process. For some titanium alloy components with large batches, small sizes, and complex shapes and structures, it solves the problems of low equipment utilization and low production efficiency that exist in the superplastic forming process.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal materials and processes, and in particular to a multi-cavity superplastic forming mold for small-sized titanium alloy components and its forming method. Background Technology

[0002] With the development of aerospace technology, the application scope of titanium alloys in the aerospace field continues to expand. Titanium alloy structural parts are also increasingly showing a trend of complex shapes, thin-walled curved surfaces, variable thickness, and integral structures. However, titanium alloys have high deformation resistance, severe springback, and are prone to local cracking at room temperature. Therefore, the commonly used processes at present include hot pressing, superplastic forming, and superplastic forming / diffusion bonding technology.

[0003] Superplastic forming can achieve near-net-shape forming of products, simplifying the process and improving production efficiency, especially suitable for complex-shaped, thin-walled parts. Titanium alloy superplastic forming technology is used in the aerospace industry both domestically and internationally for missile structural components, propellant tanks, fairings, and engine parts. However, this process takes approximately two days to form a single batch of products. For titanium alloy components with dimensions under 500mm that require mass production, producing one piece per batch results in low equipment utilization and relatively low production efficiency. Therefore, research on multi-cavity superplastic forming molds and forming technologies for small-sized titanium alloy components is urgently needed. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a multi-cavity superplastic forming mold and its forming method for small-sized titanium alloy components. The mold structure and process are optimized to achieve efficient forming of the product. For some titanium alloy components with large batches, small size and complex shape and structure, the problem of low equipment utilization and low production efficiency of superplastic forming process is solved.

[0005] The technical solution of the present invention is: a multi-cavity superplastic forming mold for small-sized titanium alloy components, comprising: an upper mold cover, a stripper plate, a forming mold, a base, and a positioning pin;

[0006] The base has multiple mold slots distributed in the middle for installing forming molds, and each mold slot has a mold positioning slot. Each forming mold is designed as a cylindrical structure with a positioning post at the bottom that matches the mold positioning slot, and a material unloading platform at the top. The platform's outer diameter is smaller than that of the forming mold, and it has a cavity inside to accommodate the blank to be formed. The bottom has an exhaust groove, and the center of the cavity bottom has an exhaust hole that runs through the exhaust groove. The material unloading plate has an unloading hole in the middle that is consistent with the distribution of each forming mold. The upper mold cover has an air chamber corresponding to the unloading hole, and each air chamber has an air inlet at the center, surrounded by a sealing ring. The center of the upper mold cover is connected to an air inlet pipe, which is connected to each air inlet.

[0007] Symmetrical positioning holes are provided on the edges of the base, stripper plate, and upper mold cover. After the upper mold cover, stripper plate, each forming mold and base are installed in sequence, they are connected and positioned by positioning pins through the positioning holes on each component.

[0008] Furthermore, the multi-cavity superplastic forming mold also has a set of air blowing cooling fixtures for use in conjunction with it, which are used to assist in the removal of structural parts with straight wall features that are difficult to demold from the furnace. The fixtures include an outer ring, air passage pipes, support rods, lifting columns and air inlet pipes. The air inlet pipes are connected to the outer ring and are arranged in a cross shape inside the outer ring. Each air passage pipe is connected to a position perpendicular to the plane where the outer ring is located and corresponding to each air inlet hole. Compressed air is introduced through the air inlet pipes and enters the forming mold cavity through each air passage pipe, so that the product cools down and shrinks rapidly.

[0009] Furthermore, lifting columns are designed around the upper mold cover, unloading plate, forming mold and base to facilitate the lifting of the formed structure out of the furnace;

[0010] Equipment fixing plates are designed on both the upper mold cover and the base, for installing and fixing them in the superplastic equipment respectively;

[0011] Temperature measuring holes are evenly distributed around the upper mold cover and the forming mold to facilitate temperature measurement during the forming process.

[0012] Furthermore, the upper mold cover, unloading plate, forming mold, and base are made of Ni7N heat-resistant steel, while the air inlet pipe and positioning pin are made of stainless steel.

[0013] Furthermore, the air-blowing cooling fixture is made of stainless steel.

[0014] Furthermore, the assembly gap between the unloading hole of the unloading plate and the unloading platform of the forming mold is 1-3mm on one side, the gap between the forming mold and the mold groove of the base is 1-3mm on one side, and the gap between the positioning pin and the mold positioning groove is 0.5-2mm on one side; the height of the unloading plate is 1-4mm lower than the height of the unloading platform.

[0015] Furthermore, the diameter of the sealing ring is greater than the maximum diameter of the forming mold cavity but less than the maximum outer diameter of the unloading platform.

[0016] The present invention also provides a forming method using a multi-cavity superplastic forming mold for small-sized titanium alloy components, comprising the following steps:

[0017] Step 1: Secure the assembled molding mold's upper mold cover and base equipment fixing plate to the upper and lower platforms of the superplastic equipment using bolts. After installation, remove the positioning pins.

[0018] Step 2: Apply anti-welding agent evenly to the inner cavity of the forming mold, the surface of the blank, and the lower surface of the upper mold cover. Place the blank above the stripper plate with its center aligned with the center of the forming mold cavity.

[0019] Step 3: Connect the thermocouple, close the furnace door after placing it in the furnace, heat up the superplastic equipment at a rate of 40-60℃ / h, and the final forming temperature of the mold is 890-910℃. Hold the temperature for 1 hour, then move the upper platform down to close the mold and execute the air intake procedure.

[0020] Step 4: After the product is molded, maintain pressure for 5-15 minutes, stop the air intake, raise the upper platform, and cool down the furnace to 650-800℃;

[0021] Step 5: Lift the unloading plate and hoist the product out of the furnace; For products with straight wall sections that are difficult to remove from the furnace, place the air blowing cooling device above the unloading plate. Each vertical air pipe extends into the forming mold cavity and is connected to compressed air. While blowing air to cool down, slowly lift the unloading plate to complete the product hoisting out of the furnace.

[0022] Furthermore, during the furnace loading process in step 2, the blanks are placed independently above the discharge holes corresponding to each forming mold. The maximum outer diameter of the blank is more than 10mm larger than the diameter of the sealing ring, and the maximum diameter cannot exceed the center line of the two discharge holes. If the maximum outer diameter of the blank is smaller than the discharge hole, the blank is overlapped on the discharge plate by welding lugs.

[0023] Furthermore, it is applicable to the superplastic forming process of titanium alloy components with dimensions below 500mm, enabling the forming of multiple parts in one furnace.

[0024] The advantages of this invention compared to the prior art are:

[0025] (1) This invention provides a multi-cavity superplastic forming mold for small-sized titanium alloy components, which can realize superplastic forming of multiple parts in one furnace, greatly improving equipment utilization and production efficiency, and is especially suitable for superplastic forming processes of large batches of small-sized products.

[0026] (2) This invention uses a design where forming molds of the same external dimensions share the upper mold cover, unloading plate and base. That is, two products with similar dimensions and specifications each have multiple forming molds. The mold cavities are different, but the outer diameter of the mold, the external dimensions of the unloading platform and the dimensions of the positioning column are the same. The upper mold cover, unloading plate and base are shared. Thus, after one product is formed, another product can be loaded into the furnace within the range of 500℃, realizing one furnace per day and greatly improving production efficiency.

[0027] (3) The positioning holes and positioning pins of the upper mold cover, unloading plate and base of the present invention, as well as the positioning column of the forming mold and the positioning groove of the base, can realize the rapid loading of products into the furnace, reduce the production difficulty and the requirements for the operator's skill level.

[0028] (4) The unloading plate of the present invention can realize the one-time unloading of all products, and the air blowing cooling fixture can realize the cooling and shrinkage of products with straight wall structure, thereby quickly unloading them. Attached Figure Description

[0029] Figure 1 This is an assembly diagram of a multi-cavity superplastic forming mold according to an embodiment of the present invention;

[0030] Figure 2 This is an exploded view of a multi-cavity superplastic forming mold according to an embodiment of the present invention;

[0031] Figure 3 This is the upper mold cover of the multi-cavity superplastic forming mold in an embodiment of the present invention;

[0032] Figure 4 This is the unloading plate of the multi-cavity superplastic forming mold in an embodiment of the present invention;

[0033] Figure 5 This is a forming mold for a multi-cavity superplastic forming mold according to an embodiment of the present invention;

[0034] Figure 6 This is the base of the multi-cavity superplastic forming mold according to an embodiment of the present invention;

[0035] Figure 7 This is an air-blowing cooling fixture for a multi-cavity superplastic forming mold according to an embodiment of the present invention;

[0036] Figure 8 This is a schematic diagram of the blank ear piece according to an embodiment of the present invention;

[0037] Figure 9 This is a product illustration of an embodiment of the present invention. Detailed Implementation

[0038] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0039] This invention proposes a multi-cavity superplastic forming mold for small-sized titanium alloy components, such as... Figure 1 and Figure 2 As shown, the mold includes: an upper mold cover 1, a stripper plate 2, a forming mold 3, a base 4, and a positioning pin 5. The mold also includes a set of air-blowing cooling fixtures. Figure 7 As shown, the air blowing cooling fixture, used to assist in removing structural parts that are difficult to demold from the furnace, includes an outer ring 61, an air passage pipe 62, a support rod 63, a lifting column 64, and an air inlet pipe 65.

[0040] like Figure 3 As shown, the upper mold cover 1 includes a positioning hole 11, a sealing ring 12, an equipment fixing plate 13, an air cavity 14, a lifting column 15, an air inlet pipe 16, a temperature measuring hole 17, and an air inlet 18.

[0041] Specifically, the upper mold cover 1 has an air chamber 14 at the position corresponding to the unloading hole 22. Each air chamber has an air inlet 18 at its center, and a sealing ring 12 is fixed around it. The center of the upper mold cover 1 is connected to an air inlet pipe 16, which is connected to each air inlet 18 through a five-way structure.

[0042] like Figure 4 As shown, the unloading plate 2 includes a positioning hole 21, an unloading hole 22, and a lifting column 23.

[0043] Specifically, the middle position of the unloading plate 2 has unloading holes 22 that are distributed in the same way as the forming molds 3.

[0044] like Figure 5 As shown, the forming mold 3 includes an exhaust groove 31, a positioning column 32, a discharge platform 33, a lifting column 34, a cavity 35, and a temperature measuring hole 36.

[0045] Specifically, each forming mold 3 is designed as a cylindrical structure, with a positioning post 32 at the bottom that mates with the mold positioning groove 45, and a discharge platform 33 at the top. The outer diameter of the platform is smaller than that of the forming mold 3. The interior has a cavity 35 to accommodate the blank to be formed, and a venting groove 31 is opened at the bottom. A venting hole at the center of the bottom of the cavity 35 extends through the venting groove 31. The cavity 35 of the forming mold is volume-scaled according to the different coefficients of thermal expansion of the mold material and the titanium alloy material.

[0046] like Figure 6 As shown, the base 4 includes a positioning hole 41, an equipment fixing plate 42, a hoisting column 43, a mold groove 44, and a mold positioning groove 45.

[0047] Specifically, multiple mold slots 44 are distributed in the middle of the base 4 for installing the forming mold 3, and a mold positioning slot 45 is opened in each mold slot 44.

[0048] In summary, after the upper mold cover 1, the unloading plate 2, each forming mold 3 and the base 4 are installed in sequence, they are connected and positioned by positioning pins 5 through the positioning holes on each component.

[0049] Preferably, the upper mold cover 1, the unloading plate 2, the forming mold 3 and the base 4 are made of Ni7N heat-resistant steel, and the air inlet pipe 16 and the positioning pin 5 are made of stainless steel.

[0050] Preferably, the raw material used for the air cooling fixture is stainless steel.

[0051] Preferably, the assembly gap between the unloading hole 22 of the unloading plate 2 and the unloading platform 33 of the forming mold 3 is 1-3 mm on one side, the gap between the forming mold 3 and the mold groove 44 of the base 4 is 1-3 mm on one side, and the gap between the positioning pin 32 and the mold positioning groove 45 is 0.5-2 mm on one side, which can prevent assembly interference when the mold expands at high temperature.

[0052] Preferably, the height of the unloading plate 2 is 1-4 mm lower than the height of the unloading table 33, which can achieve good mold closing between the upper mold cover and the forming mold, and the part of the blank that overlaps with the unloading plate sinks in the high temperature environment. When the blank is removed from the furnace, the unloading plate is lifted to prevent the outer wall of the product from deforming.

[0053] Preferably, the diameter of the sealing ring 12 is larger than the maximum diameter of the cavity of the forming mold 3 but smaller than the maximum outer diameter of the unloading platform 33, which can achieve a good seal and prevent air leakage when the superplastic is vented.

[0054] Preferably, after the upper mold cover 1, the unloading plate 2, the forming mold 3 and the base 4 are assembled, the positioning pin 5 should not be higher than the upper plane of the upper mold cover. After the upper mold cover 1 and the base 4 are installed on the upper and lower platforms of the equipment respectively, the positioning pin 5 should be removed.

[0055] This invention provides a multi-cavity superplastic forming method for small-sized titanium alloy components, comprising the following steps:

[0056] Step 1: Install and fix the assembled mold upper mold cover 1 and base 4 equipment fixing plates to the upper and lower platforms of the superplastic equipment with bolts. After installation, remove the positioning pins.

[0057] Step 2: Apply anti-welding agent evenly to the inner cavity of the forming mold 3, the surface of the blank, and the lower surface of the upper mold cover 1. Place the blank above the stripper plate 2 with its center aligned with the center of the forming mold cavity.

[0058] Step 3: Connect the thermocouple, close the furnace door after placing the mold in the furnace, heat the superplastic equipment at a rate of 40-60℃ / h, and set the final forming temperature of the mold to 890-910℃. Hold the mold at this temperature for 1 hour, then move the upper platform down to close the mold and execute the air intake procedure.

[0059] Step 4: After the product is molded, maintain pressure for 5-15 minutes, stop the air intake, raise the upper platform, and cool down the furnace to 650-800℃.

[0060] Step 5: Slowly raise the unloading plate to lift the product out of the furnace; For products with straight wall sections that are difficult to remove from the furnace, place the air blowing cooling device above the unloading plate. Each vertical air blowing pipe extends into the forming mold cavity and is connected to compressed air. While blowing air to cool down, slowly raise the unloading plate to lift the product out of the furnace.

[0061] Preferably, during the furnace loading process, the blanks are independently placed above the discharge holes 22 corresponding to each forming mold 3. The maximum outer diameter of the blank should be at least 10mm larger than the diameter of the sealing ring 12, and should not exceed the center line of the two discharge holes. If the maximum outer diameter of the blank is smaller than the discharge hole, it can be addressed by welding lugs, such as... Figure 8 As shown, it is placed on the unloading plate 2, so that the unloading plate 2 can be hoisted to allow all products to be unloaded.

[0062] Preferably, this method is applicable to the superplastic forming process of titanium alloy components with a specification size of less than 500mm, and can realize the forming of multiple parts in one furnace. Depending on the size of the superplastic forming equipment platform and the size of the product component, the number of mold cavities can be 2 or more, and up to 10 or even more.

[0063] The following is a specific embodiment.

[0064] Example 1

[0065] In this embodiment, as Figure 9 As shown, the small-sized titanium alloy component has a maximum outer diameter of 213mm, a height of 154mm, a straight wall section of 30mm, and a tapered section with six protruding structures. Due to the relatively complex shape and structure of the product, only superplastic forming can be used. Because of the flange edge and cutting allowance in the superplastic forming process, the straight wall section of the superplastic formed product is 40mm, making it difficult to remove from the furnace and prone to deformation during the process. The following is a detailed implementation process of the multi-cavity superplastic forming process.

[0066] Step 1: Design and manufacture a multi-cavity superplastic molding die, such as Figure 1 As shown. It includes an upper mold cover, a stripper plate, a forming mold, a base, and locating pins. The forming mold sits on the base and is engaged with the base's locating groove by locating pins; the upper mold cover, stripper plate, and base are positioned by their locating holes and locating pins.

[0067] The assembly clearance between the unloading hole of the unloading plate and the unloading platform of the forming mold is 2mm on one side, the clearance between the forming mold and the mold groove of the base is 2mm on one side, and the clearance between the positioning pin and the mold positioning groove is 1mm on one side.

[0068] The assembled mold upper mold cover and base equipment fixing plate are bolted to the upper and lower platforms of the superplastic equipment, respectively. After installation, the positioning pins are removed.

[0069] Step 2: Apply anti-welding agent evenly to the inner cavity of the forming mold, the surface of the blank, and the lower surface of the upper mold cover. Place the blank above the stripper plate with its center aligned with the center of the forming mold cavity.

[0070] Step 3: Connect the thermocouple, close the furnace door after placing the mold in the furnace, heat the superplastic equipment at a rate of 50℃ / h, and set the final forming temperature of the mold to 900℃. Hold the temperature for 1 hour, then move the upper platform down to close the mold and execute the air intake procedure.

[0071] Step 4: After the product is molded, maintain pressure for 10 minutes, stop the air intake, raise the upper platform, and cool it down to 750℃ with the furnace. Then open the furnace door and remove the product from the furnace.

[0072] Step 5: Place the air blowing cooling device above the unloading plate. Each vertical air blowing pipe extends into the forming mold cavity and is connected to compressed air. While blowing air to cool down, slowly lift the unloading plate to achieve rapid product hoisting and unloading from the furnace.

[0073] It is understood that this invention has been described through embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of this invention. Furthermore, under the teachings of this invention, these features and embodiments can be modified to adapt to specific circumstances without departing from the spirit and scope of this invention. Therefore, this invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are protected by this invention.

[0074] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A multi-cavity superplastic forming mold for small-sized titanium alloy components, characterized in that, include: Upper mold cover (1), unloading plate (2), forming mold (3), base (4) and positioning pin (5); The base (4) has multiple mold slots (44) distributed in the middle for mounting the forming molds (3). Each mold slot (44) has a mold positioning slot (45). Each forming mold (3) is designed as a column structure with a positioning post (32) at the bottom that mates with the mold positioning slot (45). The top has a discharge platform (33) with an outer diameter smaller than that of the forming mold (3). The interior has a cavity (35) to accommodate the blank to be formed, and the bottom has an exhaust groove (31). The bottom center of the cavity (35) has an exhaust hole that extends to the exhaust groove (31); the middle position of the stripper plate (2) has an exhaust hole (22) that is consistent with the distribution of each forming mold (3); the position on the upper mold cover (1) corresponding to the exhaust hole (22) is an air cavity (14), the center of each air cavity is an air inlet (18), and a sealing ring (12) is fixed around it; the center of the upper mold cover (1) is connected to an air inlet pipe (16), and the air inlet pipe (16) and each air inlet (18) are connected to each other; Symmetrical positioning holes are provided on the edges of the base (4), the unloading plate (2) and the upper mold cover (1). After the upper mold cover (1), the unloading plate (2), each forming mold (3) and the base (4) are installed in sequence, they are connected and positioned by positioning pins (5) through the positioning holes on each component.

2. The multi-cavity superplastic forming mold for small-sized titanium alloy components according to claim 1, characterized in that: The multi-cavity superplastic forming mold also has a set of air blowing and cooling fixtures for use in conjunction with it to assist structural parts with straight walls that are difficult to demold in exiting the furnace. The fixtures include an outer ring (61), an air pipe (62), a support rod (63), a lifting column (64), and an air inlet pipe (65). The air inlet pipe (65) is connected to the outer ring (61) and is arranged in a cross shape inside the outer ring (61). Each air pipe (62) is connected to the plane perpendicular to the outer ring (61) and at the position corresponding to each air inlet hole (18). Compressed air is introduced through the air inlet pipe (65) and enters the cavity of the forming mold (3) through each air pipe (62), so that the product cools down and shrinks quickly.

3. The multi-cavity superplastic forming mold for small-sized titanium alloy components according to claim 1, characterized in that: Lifting columns are designed around the upper mold cover (1), unloading plate (2), forming mold (3) and base (4) to facilitate the lifting of the formed structure out of the furnace; Equipment fixing plates are designed on the upper mold cover (1) and the base (4) respectively for fixing them in the superplastic equipment; Temperature measuring holes are evenly provided around the upper mold cover (1) and the forming mold (3) to facilitate temperature measurement during the forming process.

4. The multi-cavity superplastic forming mold for small-sized titanium alloy components according to claim 1, characterized in that: The upper mold cover (1), unloading plate (2), forming mold (3), and base (4) are made of Ni7N heat-resistant steel, while the air inlet pipe (16) and positioning pin (5) are made of stainless steel.

5. The multi-cavity superplastic forming mold for small-sized titanium alloy components according to claim 2, characterized in that: The air-blowing cooling fixture is made of stainless steel.

6. The multi-cavity superplastic forming mold for small-sized titanium alloy components according to claim 1, characterized in that: The assembly gap between the unloading hole (22) of the unloading plate (2) and the unloading platform (33) of the forming mold (3) is 1-3 mm on one side; the gap between the forming mold (3) and the mold groove (44) of the base (4) is 1-3 mm on one side; the gap between the positioning column (32) and the mold positioning groove (45) is 0.5-2 mm on one side; the height of the unloading plate (2) is 1-4 mm lower than the height of the unloading platform (33).

7. The multi-cavity superplastic forming mold for small-sized titanium alloy components according to claim 1, characterized in that: The diameter of the sealing ring (12) is greater than the maximum diameter of the cavity (35) of the forming mold (3) but less than the maximum outer diameter of the unloading platform (33).

8. A forming method using a multi-cavity superplastic forming mold for small-sized titanium alloy components as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Step 1: Install the upper mold cover (1) and the equipment fixing plate of the base (4) of the assembled forming mold onto the upper platform and lower platform of the superplastic equipment with bolts respectively. After installation, remove the positioning pin (5). Step 2: Apply anti-welding agent evenly to the inner cavity (35) of the forming mold (3), the surface of the blank and the lower surface of the upper mold cover (1). Place the blank above the stripper plate (2) and align its center with the center of the forming mold cavity. Step 3: Connect the thermocouple, close the furnace door after placing it in the furnace, heat up the superplastic equipment at a rate of 40-60℃ / h, and the final forming temperature of the mold is 890-910℃. Hold the temperature for 1 hour, then move the upper platform down to close the mold and execute the air intake procedure. Step 4: After the product is molded, maintain pressure for 5-15 minutes, stop the air intake, raise the upper platform, and cool down the furnace to 650-800℃; Step 5: Lift the unloading plate (2) and lift the product out of the furnace; For products with straight wall sections that are difficult to remove from the furnace, place the air blowing cooling device above the unloading plate. Each vertical air pipe (62) extends into the forming mold cavity and is connected to compressed air. While blowing air to cool down, slowly lift the unloading plate to complete the lifting and removal of the product from the furnace.

9. The forming method for small-sized titanium alloy components using a multi-cavity superplastic forming mold according to claim 8, characterized in that: During the furnace loading process in step 2, the blanks are placed independently above the unloading holes (22) corresponding to each forming mold (3). The maximum outer diameter of the blank is more than 10mm larger than the diameter of the sealing ring (12), and the maximum diameter cannot exceed the center line of the two unloading holes. If the maximum outer diameter of the blank is smaller than the unloading hole, the blank is overlapped on the unloading plate (2) by welding ear pieces.

10. The forming method using a multi-cavity superplastic forming mold for small-sized titanium alloy components according to claim 8, characterized in that: It is applicable to the superplastic forming process of titanium alloy components with a specification size of less than 500mm, and can achieve the forming of multiple parts in one furnace.

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