A spinning additive composite forming method for titanium alloy double-flange conical complex parts

Abstract

The present invention discloses a method for the composite forming of titanium alloy conical complex parts with double flanges by spinning additive manufacturing, comprising the following steps: prefabricating a circular sheet blank of corresponding size; heating the circular sheet blank and fixing it on a shear spinning core die; designing a corresponding core die and a butterfly-shaped roller for shear spinning according to the semi-cone angle of the conical part of the component to be manufactured, determining the gap between the roller and the core die according to a sine law, using a double roller for shear spinning, and using a laser for supplementary heat during spinning to form a conical preform with a bottom flange; designing a butterfly-shaped roller for shoveling, using a laser to heat the shoveling deformation zone, and shoveling from the end of the conical preform along the generatrix direction to form a middle short flange structure, and using an arc cladding additive method to radially add material to the flange. The present invention is obtained by plastic deformation, retaining complete metal streamlines, especially the flange root as a stress concentration area, thereby greatly improving the bearing capacity and service life of the part.

Description

Technical Field

[0001] The present invention relates to the field of plastic forming and additive manufacturing of metal materials, and in particular to a spinning additive composite forming method for a titanium alloy double-flange conical complex part. Background Art

[0002] Titanium alloys are alloys made of titanium and other metals. They possess high specific strength and stiffness, as well as excellent corrosion and oxidation resistance. They are widely used in the manufacture of core components for high-end aerospace and defense equipment that withstand heavy loads and high temperatures. Aircraft engine nozzles, with their double-flange conical structure, are typically manufactured from titanium alloys because they must withstand high temperatures, high pressures, and high-velocity gases.

[0003] The commonly used manufacturing method for these parts in China is "forging or casting + machining." This not only results in low material utilization and long processing cycles, but also in the tapered section's thin walls, which are prone to deformation during machining and the severing of material fibers. This can easily lead to dimensional inaccuracies and severe strength and toughness deficiencies, resulting in stress concentration and microcracks during service, significantly reducing load-bearing capacity and fatigue life.

[0004] In order to meet the current demand for high thrust-to-weight ratio engines such as large thrust rockets, engine nozzle parts need to have higher mechanical properties, and at the same time, the utilization rate of materials needs to be improved to reduce costs. Summary of the Invention

[0005] In order to overcome the limitations of the existing technology for preparing complex titanium alloy conical parts with double flanges, such as insufficient load-bearing capacity, low forming precision and low material utilization, the present invention provides a spinning additive composite forming method for complex titanium alloy conical parts with double flanges.

[0006] The present invention can achieve complete near-net forming of complex conical parts with double flanges, avoid cutting of metal streamlines, ensure excellent mechanical properties of the parts, and significantly improve material utilization and reduce costs.

[0007] The present invention is achieved through the following technical solutions:

[0008] A method for spinning additive composite forming of a titanium alloy double-flange conical complex part comprises the following steps:

[0009] Step 1: Based on the wall thickness, diameter and machining allowance of the component, according to the principle of constant volume and the sine law that the wall thickness should follow during shear spinning, prefabricate a circular sheet blank of corresponding size;

[0010] Step 2: Heat the circular sheet blank in a heating furnace to about 480℃-550℃ (optimal 500℃), then quickly clamp it on the spinning machine and fix it on the shear spinning core mold with a tail top;

[0011] Step 3: Based on the semi-cone angle of the tapered part of the component to be manufactured, the corresponding core mold and butterfly-shaped spinning wheel for shearing and spinning are designed. The gap between the spinning wheel and the core mold is determined according to the sine law. To improve the plastic deformation ability of the titanium alloy material, the circular sheet blank is preheated and shearing and spinning is performed using a double spinning wheel. During spinning, laser heating is used to form a tapered preform with a bottom flange.

[0012] Step 4: Design a butterfly-shaped rotary wheel for scraping and rotating, use laser to heat the scraping and rotating deformation zone, and scrape and rotate the rotary wheel from the end of the conical preform along the generatrix direction to form a low flange structure in the middle;

[0013] Step 5: Based on the short flange obtained by shovel spinning, the arc cladding additive method is used to add material radially on the rotated flange to further increase the flange size;

[0014] Step 6: Trim the middle flange, cut off the bottom, and process the mounting holes in the middle flange.

[0015] In the above step 3, the circular sheet blank is clamped on the main shaft of the spinning machine through the tail top, and the double rollers are symmetrically distributed on the left and right sides. The laser heater spot is aligned with the blank of the same cross section as the rollers, and the spot can move synchronously with the feeding of the rollers; the temperature of the deformation zone of the blank is heated to about 750-950 ° C by laser, so that the temperature of the deformation zone of the blank is above the recrystallization temperature. During shear spinning, the gap between the butterfly roller and the core mold is set to t = t0sinα, the roller fillet radius is about (1-3)t0, the roller is fed along the generatrix direction of the conical core mold, and the outlet flange structure is reserved at the mouth according to the flange size of the part mouth;

[0016] Where t0 is the wall thickness of the blank, and α is the semi-cone angle of the tapered part.

[0017] In step 4, the conical preform obtained by shear spinning is used as the basis. A butterfly-shaped roller with a corner radius of (0.1-0.5)t0 is used for shoveling, and two rollers are symmetrically arranged. During forming, the rollers first move radially to squeeze the blank, then feed along the generatrices of the conical core mold toward the small end. Laser heating is used to maintain the temperature of the deformed zone on the roller side at 750-950°C. The extruded blank is extruded to a depth of (0.2-0.5)t, where t is the wall thickness of the conical blank.

[0018] In the above step five, based on the conical part with a short flange in the middle obtained by shoveling, arc cladding is used to perform stacking cladding on the basis of the short flange. During the arc additive process, the arc cladding welding gun is located directly above the short flange structure and its position remains unchanged. The workpiece rotates with the main shaft, and the flange height reaches the required size requirement by continuously stacking on the short flange.

[0019] In the above step 1, the circular plate blank is titanium alloy.

[0020] Compared with the prior art, the present invention has the following advantages and effects:

[0021] The conical blank with a short flange obtained by the present invention is obtained through plastic deformation, retaining complete metal streamlines, especially the flange root which is a stress concentration area, thereby greatly improving the load-bearing capacity and service life of the parts.

[0022] The present invention avoids the waste of metal materials in the traditional "casting / forging + cutting" preparation, realizes near-net forming with little or no cutting, greatly improves the material utilization rate of expensive metals such as titanium alloy, and saves manufacturing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic structural diagram of a titanium alloy double-flange conical complex part prepared by the present invention.

[0024] Figure 2 Schematic diagram of a conical preform obtained by shear spinning.

[0025] Figure 3 It is a complex conical part with a low flange in the middle obtained by shovel forming.

[0026] Figure 4 This is the part obtained by arc additive manufacturing on the short flange.

[0027] Figure 1-4 Reference numerals in the accompanying drawings: rotary wheel 1; conical preform 2; center plate 3; core mold 4; main shaft 5; blank 6; rotary wheel for scraping and spinning 1A; welding gun 1B; additive part 1C. DETAILED DESCRIPTION

[0028] The present invention is described in further detail below with reference to specific embodiments.

[0029] Example

[0030] Figure 1 The figure shows the structure of a complex conical part with double flanges, made of TC11 titanium alloy. The specific steps of the spinning-additive forming process are as follows:

[0031] (1) Calculation of billet size: Figure 1This is a schematic diagram of a complex conical component with two flanges, made of TC11 titanium alloy. The requirements are a semi-cone angle θ = 30°, a center flange wall thickness t = 3mm, a bottom flange wall thickness t0 = 6mm, a center flange height H = 50mm, a bottom diameter d = 85mm, a mouth diameter D = 230mm, a thick conical section thickness t1 = 3mm, and a thinner section thickness t2 = 1.5mm. Based on the part geometry, a composite forming method combining shear spinning and shovel spinning with arc additive manufacturing is employed. According to the shear spinning sine law, the original blank wall thickness is t1 / sinθ = 6mm, the same as the mouth flange wall thickness. Based on the principle of volume invariance and a 5mm trimming allowance on one side, the diameter of the circular slab is calculated to be 240mm.

[0032] (2) Schematic diagram of shear spinning forming conical preform Figure 2 As shown. A conical core mold with a semi-cone angle of 30° and a small end diameter of 85mm and two butterfly-shaped rollers with a fillet radius of 8mm were designed and manufactured. A roller feed ratio of 0.2mm / r was used for shear spinning, and the calculated gap between the roller and the core mold was 3mm. The forming process is as follows: first, the shear core mold is fixed on the main shaft of the spinning machine; then the center plate blank is installed on the core mold and tightened by the tail. The main shaft drives the core mold and the blank to rotate at high speed, and the two symmetrically arranged rollers are fed along the main line direction. At the same time, the rollers leave a distance at the mouth and do not participate in the spinning forming, forming a mouth flange structure.

[0033] (3) Schematic diagram of the structure with a short flange in the middle prepared by shovel-turn forming Figure 3 As shown. Two disc-shaped rollers with a fillet radius of 1.5mm were designed and manufactured. A roller feed ratio of 0.2mm / r and an extrusion depth of 1.5mm were used for shoveling and spinning. The gap between the roller and the core mold was 1.5mm. The forming process is as follows: Based on the conical preform obtained by shear spinning, a shoveling and spinning roller is used. The main shaft drives the billet to rotate. The shoveling and spinning roller first radially squeezes into the conical billet to a depth of 1.5mm, and then feeds toward the small end along the generatrix direction to the middle flange position, forming a middle low flange structure.

[0034] (4) Schematic diagram of the middle high flange structure prepared by arc additive manufacturing Figure 4 As shown in the figure, based on the structure with a low central flange fabricated by shovel-rotating forming, a welding gun for arc additive manufacturing was designed. The arc additive manufacturing process is as follows: The conical part with the flange rotates along the mandrel driven by the main shaft. The welding gun is fixed directly above the low central flange. The welding gun melts the titanium alloy wire and deposits it on the low flange. As the part rotates, the molten wire continues to build up on the low flange until the desired height of the central flange is reached.

[0035] (5) The complex conical parts with double flanges obtained by spinning and additive manufacturing are machined by trimming, cutting and drilling to obtain Figure 1 Parts shown.

[0036] As described above, the present invention can be implemented better.

[0037] The implementation methods of the present invention are not limited to the above-mentioned embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A titanium alloy double flange conical complex part spinning additive composite forming method, characterized in that The steps include: Step 1: Based on the wall thickness, diameter and machining allowance of the component, according to the principle of constant volume and the sine law that the wall thickness should follow during shear spinning, prefabricate a circular sheet blank of corresponding size; Step 2: Heat the circular sheet blank to 480℃-550℃ in a heating furnace, then quickly clamp it on the spinning machine and fix it on the shear spinning core mold with a tail top; Step 3: Based on the semi-cone angle of the tapered part of the component to be manufactured, the corresponding core mold and butterfly-shaped spinning wheel for shearing and spinning are designed. The gap between the spinning wheel and the core mold is determined according to the sine law. To improve the plastic deformation ability of the titanium alloy material, the circular sheet blank is preheated and shearing and spinning is performed using a double spinning wheel. During spinning, laser heating is used to form a tapered preform with a bottom flange. Step 4: Design a butterfly-shaped rotary wheel for scraping and rotating, use laser to heat the scraping and rotating deformation zone, and scrape and rotate the rotary wheel from the end of the conical preform along the generatrix direction to form a low flange structure in the middle; Step 5: Based on the short flange obtained by shovel spinning, the arc cladding additive method is used to add material radially on the rotated flange to further increase the flange size; Step 6: Trim the middle flange, cut off the bottom, and process the mounting holes in the middle flange.

2. The method for spinning additive composite forming of titanium alloy double-flange conical complex parts according to claim 1 is characterized in that: In step three, the circular sheet blank is clamped on the main shaft of the spinning machine through the tail top, and the double rollers are symmetrically distributed on the left and right. The laser heater spot is aimed at the blank with the same cross section as the rollers, and the spot can move synchronously with the feed of the rollers; the temperature of the blank deformation zone is heated to 750-950℃ by laser, so that the temperature of the blank deformation zone is above the recrystallization temperature. During shear spinning, the gap between the butterfly roller and the core mold is set to t = t 0sinα, the radius of the wheel corner is (1-3) t 0. The rotary wheel feeds along the generatrix direction of the conical core mold, and according to the size of the flange at the mouth of the part, an outlet flange structure is reserved at the mouth; Where, t 0 is the wall thickness of the blank, and α is the semi-cone angle of the tapered part.

3. The method for spinning additive composite forming of titanium alloy double-flange conical complex parts according to claim 1 is characterized in that: In step 4, based on the conical preform obtained by shear spinning, a butterfly-shaped spinning wheel is used for shoveling, and the radius of the wheel corner is (0.1-0.5) t 0, using double rollers symmetrically distributed on the left and right; during forming, the rollers first move radially to squeeze the blank, and then feed toward the small end along the busbar of the tapered core mold; laser is used to heat the deformation zone of the blank on the roller side to keep its temperature at 750-950℃.

4. The method for spinning additive composite forming of titanium alloy double-flange conical complex parts according to claim 3 is characterized in that: The extrusion into the blank refers to the depth of extrusion into the blank (0.2-0.5) t , t is the wall thickness of the tapered blank.

5. The method for spinning additive composite forming of titanium alloy double-flange conical complex parts according to claim 1, characterized in that: In step five, based on the conical part with a short flange in the middle obtained by shovel rotation, arc cladding is used to perform stacking cladding on the basis of the short flange. During the arc additive process, the arc cladding welding gun is located directly above the short flange structure and its position remains unchanged. The workpiece rotates with the main shaft, and the flange height reaches the required size requirement by continuously stacking on the short flange.

6. The method for spinning additive composite forming of titanium alloy double-flange conical complex parts according to claim 1, characterized in that: In step 1, the circular sheet blank is titanium alloy.

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