A method and device for forming a high-temperature titanium alloy variable-curvature thin-walled conical member

Abstract

The application relates to a high-temperature titanium alloy variable-curvature thin-wall conical cylinder component forming method and device, and belongs to the field of high-temperature titanium alloy complex profile component precision forming. The application solves the problems of low precision, large material performance loss and low forming efficiency in the forming process of the high-temperature titanium alloy complex profile component in the prior art. The high-temperature titanium alloy variable-curvature thin-wall conical cylinder component forming process method comprises the following steps: S1, blanking and pretreatment; S2, mold preheating: the mold is preheated to 850-880 DEG C; S3, the blank is preheated for 10-35 min to a forming temperature of 850-880 DEG C; S4, skin hot forming: starting forming, pressure maintaining for 30-50 min; S5, skin forming post-treatment; S6, welding of the split skin; S7, cylinder vacuum thermal expansion forming: the cylinder assembled in the thermal expansion forming tool is put into a vacuum thermal expansion forming equipment and heated to 850 DEG C, and after uniform heating for 1 hour, the cylinder is subjected to thermal expansion forming through segmented pressure; and S8, cylinder expansion post-treatment. The application realizes low loss and high profile precision of the high-temperature titanium alloy conical cylinder component forming performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of precision hot forming of high-temperature titanium alloy complex profile components, and particularly relates to a forming method and device for a high-temperature titanium alloy variable-curvature thin-wall conical cylinder component. BACKGROUND

[0002] As a newly developed titanium alloy material, high-temperature titanium alloy (Ti60) has high specific strength and excellent properties such as high-temperature resistance, good strength at 600 DEG C, and high-temperature creep performance, and is increasingly widely used in the field of aerospace.

[0003] The high-temperature titanium alloy is generally used in the head cone part of a high-speed aircraft as a central cone component, has a large variable diameter, a complex aerodynamic profile, and requires high profile precision and great forming difficulty. The titanium alloy is generally formed by using a hot forming process, i.e., after the sheet material is heated to a reasonable temperature, the upper and lower molds are closed, the sheet material is deformed and attached to the mold, and the required part profile is obtained.

[0004] However, there is no reliable forming process parameter and process device for the complex profile high-temperature titanium alloy conical cylinder component by using the hot forming process at present, and the traditional hot forming and the hot forming and thermal expansion combined process scheme cannot meet the requirements of component profile precision and performance loss. SUMMARY

[0005] In view of the above analysis, the present application aims to provide a forming method and device for a high-temperature titanium alloy variable-curvature thin-wall conical cylinder component, to solve at least one of the problems of low profile precision, large material performance loss, and low forming efficiency in the forming process of the existing thin-wall conical cylinder component.

[0006] In one aspect, the present application provides a forming method for a high-temperature titanium alloy variable-curvature thin-wall conical cylinder component, comprising the following steps:

[0007] S1, blanking and pretreatment: according to the split skin model of the cylinder body, the size of the unfolded flat blank is obtained in the software, and the blank is cut and pretreated;

[0008] S2, mold preheating: the hot forming mold is installed on the hot forming press, and is preheated to 850-880 DEG C; the convex model surface of the hot forming mold is matched with two mirror-symmetrically arranged half-cylinder skins, and the mold as a whole is saddle-shaped;

[0009] S3, blank preheating: the high-temperature titanium alloy blank is placed on the convex die of the preheated hot forming mold, and is preheated for 10-15 min after the mold is closed, to a forming temperature of 850-880 DEG C; the high-temperature titanium alloy blank is arranged in a two-half-cylinder shape, and the small end of the conical cylinder is close to the symmetry axis;

[0010] S4, hot forming: the hot forming press is started, and the high-temperature titanium alloy blank is formed into a conical cylinder component;S4, skin hot forming: start forming, after 10-20 min of pressure maintaining, take out the formed cylinder skin;

[0011] S5, skin forming post-processing: after the formed cylinder skin is subjected to alkali collapse and acid pickling, laser cutting is performed to obtain cylinder split skin;

[0012] S6, welding split skin: after the split skin obtained in step S5 is subjected to cleaning treatment, it is placed in a welding tool and welded into a cylinder under argon protection;

[0013] S7, cylinder vacuum hot bulging: after the welded cylinder is assembled according to the profile in the hot bulging tool and placed in the vacuum hot bulging equipment and heated to 850°C, the pressure is loaded in stages to make the cylinder reach the design size, and then the size is fixed by pressure maintaining and temperature maintaining;

[0014] S8, cylinder bulging post-processing: after cooling, the cylinder is taken out from the hot bulging tool, and the edge is cut to obtain the final conical cylinder component.

[0015] Exemplarily, in step S7, the hot bulging tool includes a base, a bulging segment installed on the base, and a bulging core matched with the bulging segment; the base is provided with a guide groove for sliding of the bulging segment.

[0016] Further, in step S7, the segmented pressure loading includes two stages, the first stage of pressure loading makes the hot bulging equipment platform closely fit the bulging core, and the second stage of pressure loading makes the bulging segment slide outward along the guide groove of the base to reach the design size of the conical cylinder component.

[0017] Specifically, in step S7, the first stage of pressure loading is 10 tons, and the second stage of pressure loading is 50 tons.

[0018] Further, in step S7, after reaching the design size of the conical cylinder component, pressure maintaining and temperature maintaining are performed, the pressure is 50 tons, and the temperature maintaining time is 45 min.

[0019] On the other hand, the embodiment of the present application provides a high-temperature titanium alloy variable-curvature thin-walled conical cylinder component forming device for the forming process method, which includes a hot forming die, a welding tool and a hot bulging tool.

[0020] Specifically, the hot forming die includes a punch and a die, wherein the punch is below and the die is above; the die is mirror-symmetrically arranged with the two half-cylinder skins after splitting, wherein the small end of the conical cylinder is close to the symmetry axis; the draft angle of the edge part of the hot forming die is 3°-5°.

[0021] Further, the welding tool includes a support assembly, a positioning assembly, an inner support plate and a welding protection airflow channel slot plate;

[0022] The positioning assembly is arranged along the axis of the support assembly and is connected with the support assembly through an inner support plate; the welding protection gas flow channel groove plate is symmetrically installed on the outer edge of both sides of the inner support plate;

[0023] The support assembly comprises two outer ring plates, one or more outer reference plates and a pull rod, the outer ring plate and the outer reference plate are fixedly connected through the pull rod, and the outer ring plate and the outer reference plate are provided with holes matched with the size of the pull rod at corresponding positions;

[0024] The positioning assembly comprises two end reference plates, one or more internal reference plates, one reference shaft, a gasket ring and a fastening nut, the reference shaft passes through the center of the reference plate and is fixedly connected with the reference plate through the gasket ring and the fastening nut.

[0025] Exemplarily, the hot expansion forming tool comprises a base, an expansion lobe installed on the base, and an expansion core matched with the shape of the expansion lobe.

[0026] The base is provided with a guide groove, an adjusting bolt and a nut, the bottom of the expansion lobe is provided with a sliding block matched with the guide groove of the base, and the sliding block is fixed at a specific position of the guide groove through the adjusting bolt and the nut.

[0027] Notably, the size of the hot expansion forming tool profile is L1=L×0.996, and the size of the hot forming die profile is L2=L1×0.996=L×0.996×0.996=L×0.992, wherein L is the size of the target component profile.

[0028] Compared with the prior art, the present application can at least achieve one of the following beneficial effects:

[0029] 1. The present application precisely controls and reduces the high-temperature hot forming time, avoids the formation of an oxygen-rich layer, reduces the loss of material performance, and can reduce the generation of thermal stress, thereby preventing product deformation and improving product size accuracy; shortening the high-temperature forming time can also reduce energy consumption and production cost.

[0030] 2. In the hot forming process of the present application, the two half-cylinder skins after parting are designed in a set of molds and arranged in sequence along the axial direction, the two half-cylinder skins are arranged in mirror image symmetry, the mirror image symmetry axes of the two half-cylinder skins are perpendicular to the axial direction of the half-cylinder skin, and the small end of the conical cylinder is close to the symmetry axis, so that the forces of each part in the mold are balanced, the lateral force generated during the forming process is effectively avoided, and the dislocation of the mold and the deformation of the skin caused thereby are also avoided; and the cylinder component is formed at one time, thereby improving the hot forming efficiency.

[0031] 3. The present application sets a welding protection gas flow channel on the welding tool, which protects the inner side weld, and compared with filling protective gas in the entire cylinder, the welding quality is guaranteed while the efficiency is improved.

[0032] 4. The application precisely controls the temperature of the hot expansion forming process, and carries out multi-stage pressure control, realizes the precise adjustment of the core expansion reduction by controlling the pressure and node of each pressurization, ensures the cylinder expansion amount, and controls the final surface accuracy of the cylinder to be ±0.3mm.

[0033] 5. The application adopts high-temperature hot forming and vacuum hot expansion composite process, ensures low loss of material performance while improving the surface accuracy; determines the process processing size chain according to the processing sequence, and determines the scaling coefficient of the mold and tooling according to the difference between the thermal expansion coefficients of the mold and tooling material and the high-temperature titanium alloy (Ti60) material, respectively scales the hot forming mold surface and the hot expansion tooling surface, and through double scaling, the surface size after forming is ensured. Accurate.

[0034] In the application, the above technical solutions can be combined with each other to realize more preferred combination solutions. Other features and advantages of the application will be described in the subsequent specification, and some advantages will become apparent from the specification or will be understood by implementing the application. The purpose and other advantages of the application can be achieved and obtained from the contents specifically pointed out in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0035] The accompanying drawings are included to provide a further understanding of the application and are incorporated herein and constitute a part of the application. The drawings illustrate embodiments of the application and, together with the description, serve to explain the principles of the application. In the drawings:

[0036] Figure 1 It is a schematic diagram of the variable curvature thin-walled conical member of the application;

[0037] Figure 2 It is a schematic diagram of the hot forming mold of the application Figure 1 ;

[0038] Figure 3 It is a schematic diagram of the hot forming mold of the application Figure 2 ;

[0039] Figure 4 It is a schematic diagram of the welding tooling of the application;

[0040] Figure 5 It is a schematic diagram of the hot expansion tooling of the application.

[0041] Reference signs:

[0042] 1-die; 2-punch; 3-skin; 401-end reference plate; 402-internal reference plate; 403-external reference plate; 5-outer ring plate; 6-inner support plate; 7-reference shaft; 8-gasket ring; 9-fastening nut; 10-runner slot plate; 11-pull rod; 12-base; 1201-guide groove; 13-expansion core; 14-expansion petal. DETAILED DESCRIPTION

[0043] The preferred embodiments of the present application will be described in detail below with reference to the drawings, which form a part of this application, and together with the description, illustrate the principles of the application, but are not intended to limit the scope of the application.

[0044] One specific embodiment of the present application discloses a forming process method of a high-temperature titanium alloy variable-curvature thin-walled conical cylinder component, comprising the following steps:

[0045] S1, blanking and pretreatment: according to the cylinder split skin model, the unfolded flat blank size is obtained in the software and cut down and pretreated;

[0046] S2, mold preheating: the hot forming mold is installed on the hot forming press and preheated to 850-880℃; the convex model surface of the hot forming mold matches the two mirror-symmetrically arranged half-cylinder skins, and the mold as a whole is saddle-shaped;

[0047] S3, blank preheating: the high-temperature titanium alloy blank is placed on the convex die of the preheated hot forming mold, and after the mold is closed, it is preheated for 10-15min to the forming temperature of 850-880℃; the high-temperature titanium alloy blank is arranged symmetrically in two half-cylinder shapes, and the small end of the conical cylinder is close to the symmetry axis;

[0048] S4, skin hot forming: start forming, take out the formed cylinder skin after pressure maintaining for 10-20min;

[0049] S5, skin forming post-treatment: after the formed cylinder skin is subjected to alkali collapse pickling, laser cutting is performed to obtain the cylinder split skin;

[0050] S6, welding split skin: the split skin obtained in step S5 is cleaned and placed in a welding tool, and welded into a cylinder under argon protection;

[0051] S7, cylinder vacuum hot bulging: the welded cylinder is assembled according to the profile in the hot bulging tool and placed in the vacuum hot bulging equipment to heat to 850℃, and after uniform temperature for 1 hour, the pressure is loaded in stages to make the cylinder reach the designed size, and then the size is fixed by heat preservation and pressure maintaining;

[0052] S8, cylinder bulging post-treatment: after cooling, the cylinder is taken out from the hot bulging tool, and the edge is cut to obtain the final conical cylinder component.

[0053] Specifically, in step S1, the barrel split skin model is divided into two symmetrical half barrels along the circumference of the conical barrel component; the model is unfolded in UG software to obtain an unfolded material, and a peripheral allowance of 30-50 mm is added as the size of the skin blank; the skin blank is cut by laser cutting, the edge burrs of the blank are polished, and the flat plate blank is pre-rolled into a conical barrel, wherein the minimum radius of the barrel is greater than the minimum radius of the target barrel; graphite is coated on the upper and lower surfaces of the blank to prevent oxidation and lubrication, and after drying, the graphite bumps are polished with sandpaper to ensure smooth coating.

[0054] Further, in step S2, the manufactured hot forming die is cleaned, and after the surface of the die is sprayed with high-temperature lubricating paint, it is installed on a hot forming press, the process parameters are set, and the temperature is raised to 850-880℃.

[0055] The hot forming process designs the two half barrel skins after splitting in a set of molds, and they are arranged in mirror symmetry, wherein the small end of the conical barrel is close to the symmetry axis, so that the forces on each part of the mold are balanced, effectively avoiding the generation of lateral forces during the forming process and the resulting mold misalignment and skin deformation; and the barrel component is formed once, improving the hot forming efficiency.

[0056] Illustratively, the high-temperature lubricating paint is graphite; the hot forming die material is Ni7N high-temperature stainless steel, and the mold heating rate is 2℃ / min; a too fast heating rate will result in poor thermal uniformity of the mold, affecting the forming quality of the skin; the skin material is high-temperature titanium alloy (Ti60), and according to the heat treatment characteristics of Ti60, the preheating temperature of the mold is determined to be 850-880℃; a too low preheating temperature will result in insufficient forming, and a too high preheating temperature will cause damage to the mold, thereby affecting the forming quality and stability;

[0057] In one possible design, the preheating temperature of the hot forming die is 850℃.

[0058] Further, in steps S3 and S4, when the mold temperature reaches 850-880℃, the high-temperature titanium alloy blank is placed on the convex mold of the preheated hot forming die, the high-temperature titanium alloy blank is arranged in two half barrel symmetries, wherein the small end of the conical barrel is close to the symmetry axis, the preheating time is determined according to the thickness of the blank after the mold is closed, which is 10-15 min, the blank reaches the forming temperature after the forming starts, the pressure is 20 tons, and the pressure is maintained for 10-20 min to realize the part fitting the mold and the high-temperature creep releasing internal stress; after the forming is completed, the formed barrel skin is taken out;

[0059] In one possible design, after the mold temperature reaches 850℃, the high-temperature titanium alloy blank is preheated, the blank thickness is 2 mm, the preheating time is 10 min, the hot forming starts, the forming pressure is 20 tons, and the pressure is maintained for 20 min.

[0060] Precise control and reduction of high-temperature hot forming time is less than 20 minutes, effectively avoiding the formation of oxygen-rich layer, reducing the loss of material performance; shortening the high-temperature hot forming time can also reduce the generation of thermal stress, improve the product size accuracy, and reduce energy consumption.

[0061] Preferably, in step S5, after the skin is removed by alkaline pickling, laser cutting is performed to complete the half-skin forming of the cylinder body. When cutting, the skin is not left with a margin in the arc direction, and a margin of 10-20mm is left in the length direction.

[0062] Further, in step S6, surface cleaning treatment is performed before the longitudinal weld of the skin is welded, and the metal luster is polished and wiped with acetone or alcohol to ensure the surface cleaning and welding quality; argon protection is performed during the welding process, single-sided welding is performed, and X-ray detection is performed after welding to ensure the welding quality.

[0063] Exemplarily, in step S7, the thermal expansion forming tooling includes a base, an expansion segment mounted on the base, and an expansion core matched with the expansion segment; the base is provided with a guide groove for sliding of the expansion segment;

[0064] During the thermal expansion forming process, the expansion amount of the cylinder body is adjusted by adjusting the pressing amount of the expansion core. When the cylinder body profile is small, the expansion segment is slid outward along the profile by increasing the pressing amount of the expansion core, so as to ensure the final cylinder body profile precision.

[0065] Further, in step S7, the segmented pressure loading includes two stages. The first stage of pressure loading makes the thermal expansion forming equipment platform closely fit the expansion core, and the second stage of pressure loading makes the expansion segment slide outward along the guide groove of the base to reach the design size of the conical cylinder component.

[0066] Specifically, in step S7, the first stage of pressure loading is 10 tons, and the second stage of pressure loading is 50 tons.

[0067] Further, in step S7, after reaching the design size of the conical cylinder component, pressure maintaining and heat preservation are performed, the pressure is 50 tons, and the heat preservation time is 45 minutes.

[0068] During the thermal expansion forming process, multi-stage pressure control is performed, and the pressing amount of the expansion core is accurately adjusted. In the first stage, a smaller tonnage pressure is used to make the expansion core closely fit the equipment platform, so as to ensure the close contact of the platform, the expansion core and the segment mold and the clamping precision. In the second stage, a larger tonnage pressure is used to ensure sufficient forming. While the expansion core moves downward to the bottom, each expansion segment moves in the circumferential direction to make the cylinder fully expand. According to the expansion result of the first piece, the diameter of the cylinder after expansion can be controlled by controlling the tonnage or the pressing amount of the platform, so as to realize precise control.

[0069] In another aspect, the embodiments of the present application disclose a high-temperature titanium alloy variable-curvature thin-wall conical shell component forming device for the forming process, comprising a hot forming die, a welding tool and a thermal expansion forming tool.

[0070] Specifically, the hot forming die comprises a punch and a die, wherein the punch is at the bottom and the die is at the top, and the punch and the die are positioned by a profile; the die is arranged in mirror image symmetry after being split into two half-shell skins, wherein the small end of the conical shell is close to the symmetry axis; and the draft angle of the edge part of the hot forming die is 3°-5°.

[0071] Notably, the two half-shell skins are designed in a set of dies and arranged in mirror image symmetry, wherein the small end of the conical shell is close to the symmetry axis, the profile is saddle-shaped, and the stress point is at the center of the die, so that the forces on each part of the die are balanced, effectively avoiding lateral forces in the forming process and the resulting die misalignment and skin deformation; and the shell body component is formed at one time, improving the efficiency of hot forming;

[0072] According to the hot forming temperature of the high-temperature titanium alloy material and the shape characteristics of the conical shell component, the design of the draft angle of 3°-5° can effectively reduce the friction between the shell body and the hot forming die, improve the demolding performance and the surface quality of the component; a too large draft angle will reduce the dimensional accuracy of the component, especially the accuracy of the edge area; and a too small draft angle will lead to difficulty in demolding and increase the die wear.

[0073] In a possible design, the draft angle of the edge part of the hot forming die is 5°.

[0074] Further, the welding tool comprises a support assembly, a positioning assembly, an inner support plate and a welding protective gas flow channel groove plate;

[0075] The positioning assembly is arranged along the central axis of the support assembly and connected with the support assembly through the inner support plate; and the welding protective gas flow channel groove plate is symmetrically installed on the outer edges of the inner support plate;

[0076] The support assembly comprises two outer ring plates, one or more outer reference plates and a pull rod, and holes with sizes matched with the pull rod are formed in corresponding positions of the outer ring plates and the outer reference plates, and the outer ring plates and the outer reference plates are fixedly connected through the pull rod.

[0077] The positioning assembly comprises two end reference plates, one or more internal reference plates, one reference shaft, a grommet and a fastening nut, the reference shaft passes through the center of the reference plates and is fixedly connected with the reference plates through the grommet and the fastening nut.

[0078] Specifically, the half-shell skin is clamped between the inner support plate and the outer ring plate and the outer reference plate, and is assembled according to the size of the inner support plate, wherein the inner support plate plays a supporting and fixing role; and the axial length of the two half-shell skins is positioned through the outer ring plates at both ends, and the two half-shell skins are clamped on the tool through the tensioning central shaft.

[0079] Exemplarily, the hot expansion tooling includes a base, expansion petals mounted on the base, and an expansion core matched with the shape of the expansion petals.

[0080] The base is provided with a guide groove, an adjusting bolt and a nut, the bottom of the expansion petals is provided with a sliding block matched with the guide groove of the base, and the sliding block is fixed at a specific position of the guide groove through the adjusting bolt and the nut; the gap between the sliding block and the guide groove is >0.5mm.

[0081] In a possible design, the guide groove of the base is a dovetail groove, which has the characteristics of high rigidity and good stability, and has a certain self-locking ability.

[0082] The shape of the expansion petals is the scaled part surface, the inner shape is a tapered cavity matched with the expansion core, and the expansion petals are designed to be 8-12 according to the complexity and weight of the surface.

[0083] Specifically, the material of the hot expansion tooling is stainless steel 1Cr18Ni9Ti, the gap between the expansion petals is 5-10mm compared with the scaled part surface, the expansion petals are symmetrically distributed according to the outer surface, and the minimum thickness is 30mm to ensure the rigidity; each expansion petal is provided with a processing marking line for positioning the position of the cylinder when assembling the cylinder before expansion.

[0084] Exemplarily, the base is also designed with a lifting device, and the surface of the base is marked with initial assembly position lines of the expansion petals and the expansion core.

[0085] Specifically, the expansion core is a hollow cylinder with a taper, which is designed according to the deformation amount of the cylinder after welding and the measured accuracy size of the surface before correction; during the hot expansion process, the expansion amount of the cylinder is adjusted by adjusting the pressing amount of the expansion core, when the surface of the cylinder is small, the expansion petals are slid outward by increasing the pressing amount of the expansion core, so as to ensure the accuracy of the final surface of the cylinder.

[0086] The assembly process of the cylinder and the hot expansion tooling: before assembly, ensure that the surface of the cylinder and the tooling is clean and undamaged, first install the expansion petals on the base according to the surface, and place them at the smallest position in the circumferential direction, then sleeve the welded cylinder on the expansion petals, and keep the bottom of the cylinder in close contact with the base.

[0087] Notably, the size of the hot expansion tooling surface is L1=L×0.996, and the size of the hot forming die surface is L2=L1×0.996=L×0.996×0.996=L×0.992, where L is the size of the target component surface.

[0088] According to the difference between the thermal expansion coefficients of the mold and tooling materials and the high-temperature titanium alloy (Ti60) material, the size chain is determined, the hot forming die surface and the hot expansion tooling surface are scaled respectively, and through double scaling, the accuracy of the surface size after forming is ensured.

[0089] Specifically, the hot forming die adopts Ni7N high-temperature stainless steel material, the hot bulging tooling material is stainless steel 1Cr18Ni9Ti, and the profile scaling coefficient of the tooling and the die is determined according to the difference of the thermal expansion coefficients of Ti60, Ni7N and 1Cr18Ni9Ti and the tolerance requirement of the cylinder.

[0090] To sum up, the high-temperature hot forming and vacuum hot bulging composite process are adopted, and the double scaling of the die and the bulging tooling is carried out, so as to ensure the low loss of material performance and improve the profile precision; through the symmetrical design of the hot forming die, the generation of lateral force in the forming process and the resulting die misplacement and skin deformation are avoided; the high-temperature hot forming time is accurately controlled and reduced, the formation of the oxygen-rich layer is avoided, the generation of thermal stress is reduced, the material performance loss is reduced and the product size precision is improved; the multi-stage pressure control is carried out in the hot bulging process, the bulging core pressure is accurately adjusted by controlling the pressure and node of each pressurization, and the accuracy of the cylinder bulging amount and the final cylinder profile is ensured to be ≤±0.3mm.

[0091] The process method and device of the application will be further described below in combination with specific examples.

[0092] Embodiment

[0093] In this embodiment, a high-temperature titanium alloy variable-curvature thin-walled conical cylinder component is prepared, the material is Ti60, and the size characteristics of the component are as follows: the conical cylinder height is 650m, the conical cylinder wall thickness is 2mm, the profile large end diameter is 450mm, the small end diameter is 310mm, it is a complex variable-curvature feature of a pneumatic profile, and the size precision to be reached is ±0.3mm.

[0094] The number of hot bulging tooling bulges is 8; the hot forming die adopts Ni7N high-temperature stainless steel, and the hot bulging tooling material is stainless steel 1Cr18Ni9Ti; the hot bulging tooling profile size is L1=Lx0.992, and the hot forming die profile size is L2=Lx0.996.

[0095] The specific forming process is as follows:

[0096] S1, blanking and pretreatment: the cylinder split skin model is symmetrical two half cylinders along the circumference of the conical cylinder component; the development is carried out in the UG software, the developed material is obtained, and the peripheral allowance of 30mm is added as the skin blank size; the skin blank is obtained by laser cutting, the edge burrs of the blank are polished, pre-rolling bending is carried out, the flat plate blank is pre-rolled into a conical cylinder, and the minimum radius of the cylinder is greater than the minimum radius of the target cylinder; the water agent graphite is coated on the upper and lower surfaces of the blank to play the roles of anti-oxidation and lubrication, and the graphite protrusions are polished with sandpaper after air drying to ensure the coating flatness;

[0097] S2, mold preheating: clean the manufactured hot forming mold, spray high temperature lubricating paint on the surface of the mold, install on the hot forming press, the heating rate is 2 DEG C / min, heat to 850 DEG C;

[0098] S3, blank preheating: put the high temperature titanium alloy blank into the preheated hot forming mold and preheat for 10 min to the forming temperature 850 DEG C;

[0099] S4, skin hot forming: start forming, pressure 20 tons, hold for 10 min, then take out the formed cylinder skin;

[0100] S5, skin forming post-processing: after the formed cylinder skin is subjected to alkali etching and acid pickling, laser cutting is performed to obtain a cylinder split skin, and no allowance is left in the radial direction of the skin, and an allowance of 15 mm is left in the length direction;

[0101] S6, welding split skin: before longitudinal seam welding of the skin, surface cleaning treatment is performed, polishing is performed to expose metal luster, and acetone or alcohol is used for wiping to ensure surface cleaning and welding quality, and the skin is placed into a welding tool; during the welding process, argon is filled through a protection gas flow channel for protection, single-sided welding is performed, double-sided forming is performed after welding, X-ray detection is performed to ensure the welding quality, and a cylinder is obtained;

[0102] S7, cylinder vacuum hot bulging: the welded cylinder is assembled according to the profile and placed into a vacuum hot bulging device to heat to 850 DEG C, and the temperature is kept for 1 hour, then pressure is loaded in stages, the first stage is 10 tons, the hot bulging device platform is tightly combined with the bulging core, the second stage is 50 tons, the cylinder reaches the design size, then pressure is kept, the pressure is 50 tons, the holding time is 45 min, and the size is fixed;

[0103] S8, cylinder bulging post-processing: after cooling, the cylinder is taken out from the hot bulging tool, and the edge is cut to obtain a final conical cylinder component.

[0104] Through profile detection equipment detection, the profile precision is 0.25 mm, and the deformation amount requirement of the variable curvature cylinder component is met.

[0105] In summary, the high temperature hot forming and vacuum hot bulging composite process are adopted, and the mold and bulging tool are double scaled, so that the material performance is low in loss, and the profile precision is improved; through the symmetrical design of the hot forming mold, the generation of lateral force in the forming process and the resulting mold misalignment and skin deformation are avoided; the high temperature hot forming time is accurately controlled and reduced, the formation of the oxygen-rich layer is avoided, the generation of thermal stress is reduced, the material performance loss is reduced, and the product size precision is improved; the hot bulging process is controlled in multiple stages, the pressure and nodes of each pressure loading are controlled, the bulging core pressure is accurately adjusted, the cylinder bulging amount and the final cylinder profile precision are ensured to be ≤±0.3 mm.

[0106] The above description is only the preferred embodiment of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A method of forming a high temperature titanium alloy variable curvature thin walled conical section member, characterized by, The method comprises the following steps: S1, blanking and pretreatment: according to the cylinder split skin model, the unfolded flat blank size is obtained in the software and cut down and pretreated; S2, mold preheating: the hot forming mold is installed on the hot forming press and preheated to 850-880℃; the convex model surface of the hot forming mold matches with two half cylinder skins arranged in mirror symmetry along the axial direction, and the mold as a whole is saddle-shaped; S3, blank preheating: the high-temperature titanium alloy blank is placed on the convex die of the hot forming mold after preheating, and after the mold is closed, it is preheated for 10-15min to the forming temperature of 850-880℃; the high-temperature titanium alloy blank is two half-cone cylinder blanks, which are arranged in mirror symmetry along the axial direction, and the small end of the cone cylinder is close to the symmetry axis; S4, skin hot forming: start forming, take out the formed cylinder skin after pressure maintaining for 10-20min; S5, skin forming post-treatment: after the formed cylinder skin is subjected to alkali collapse pickling, laser cutting is performed to obtain the cylinder split skin; S6, welding split skin: the split skin obtained in step S5 is cleaned and placed in the welding tool, and welded into a cylinder under argon protection; S7, cylinder vacuum hot expansion: the welded cylinder is assembled according to the profile and placed in the vacuum hot expansion equipment to heat to 850℃, and after uniform heating for 1 hour, the pressure is loaded in stages to make the cylinder reach the design size, and then the size is fixed by pressure maintaining; S8, cylinder expansion post-treatment: after cooling, the cylinder is taken out from the hot expansion tool, and the edge is cut to obtain the final cone cylinder component.

2. The method of claim 1, wherein, In step S7, the hot expansion tool includes a base, an expansion segment mounted on the base, and an expansion core matched with the expansion segment; the base is provided with a guide groove for sliding of the expansion segment.

3. The method of claim 2, wherein, In step S7, the segmented pressure loading includes two stages, the first stage of pressure loading makes the hot expansion equipment platform closely fit the expansion core, and the second stage of pressure loading makes the expansion segment slide outward along the guide groove of the base to reach the design size of the cone cylinder component.

4. The method of claim 3, wherein, In step S7, the first stage of pressure loading is 10 tons, and the second stage of pressure loading is 50 tons.

5. The method of claim 3, wherein, In step S7, after reaching the design size of the cone cylinder component, pressure maintaining and heat preservation are performed, the pressure is 50 tons, and the heat preservation time is 45min.

6. A high temperature titanium alloy variable curvature thin-walled frustum component forming apparatus for use in the forming method of claims 1-5, wherein, The method comprises a hot forming mold, a welding tool and a hot expansion tool.

7. The forming device of claim 6, wherein The hot forming mold comprises a convex die and a concave die, wherein the convex die is below and the concave die is above; the mold is shaped in mirror symmetry with the two half cylinder skins after splitting, and the small end of the cone cylinder is close to the symmetry axis; the draft angle of the edge part of the hot forming mold is 3°-5°.

8. The forming device of claim 6, wherein The welding tool comprises a support assembly, a positioning assembly, an inner support plate and a welding protection airflow channel groove plate; The positioning assembly is arranged along the central axis of the support assembly and connected with the support assembly through the inner support plate; the welding protection airflow channel groove plate is symmetrically installed on the outer edges of the inner support plate; The support assembly comprises two outer ring plates, one or more outer reference plates and a pull rod, holes matched with the size of the pull rod are opened on the corresponding positions of the outer ring plates and the outer reference plates, and the outer ring plates and the outer reference plates are fixedly connected through the pull rod; The positioning assembly comprises two end reference plates, one or more internal reference plates, one reference shaft, a gasket and a fastening nut, the reference shaft passes through the center of the reference plates and is fixedly connected with the reference plates through the gasket and the fastening nut.

9. The forming device of claim 6, wherein The hot expansion tool comprises a base, an expansion segment mounted on the base, and an expansion core matched with the expansion segment in shape. The base is provided with a guide groove, an adjusting bolt and a nut, the bottom of the expansion segment is provided with a sliding block matched with the guide groove of the base, and the sliding block is fixed at a specific position of the guide groove through the adjusting bolt and the nut.

10. The forming device of claim 6, wherein The size of the hot expansion tool profile is L1=L×0.996, and the size of the hot forming die profile is L2=L1×0.996=L×0.996×0.996=L×0.992, wherein L is the size of the target component profile.

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