Forming method of high-strength titanium alloy ring-rib part

Abstract

The application relates to a high-strength titanium alloy ring muscle type part forming method and belongs to the technical field of hot forming. The technical problems of the method are solved, such as the incapability of forming an accurate heating area at a forming position, low energy efficiency and low heat utilization rate. The high-strength titanium alloy ring muscle type part forming method comprises the following steps: S1, expanding a titanium alloy strip-shaped blank according to the size of a part to form a titanium alloy strip-shaped blank; S2, preforming the titanium alloy strip-shaped blank into a circular ring shape; S3, performing thermal calibration on the preformed part; S4, performing high-frequency induction heating and rolling and flanging forming on the preformed part, and the forming process comprises three stages of semi-forming, complete forming and re-pressing and calibrating; the coupling forming gap Z during complete forming is between 1.05t and 1.15t, and t is the wall thickness of the part; and S5, performing laser three-dimensional cutting processing on the shape of the formed part to obtain a finished product. The method avoids the occurrence of material cracks and material damage caused by exceeding the plasticity and toughness of the metal.

Description

Technical Field

[0001] This invention belongs to the field of thermoforming technology, and specifically relates to a method for forming high-strength titanium alloy ring-rib type parts. Background Technology

[0002] High-strength titanium alloys possess characteristics such as low density, high specific strength, low thermal conductivity, non-magnetic properties, resistance to high and low temperatures, and corrosion resistance. Due to their unique physical and chemical properties, they are widely used as an important strategic material in fields such as aerospace, shipbuilding, weaponry, petroleum, chemical industry, energy, marine engineering, nuclear power engineering, and biomedicine.

[0003] High-strength titanium alloy parts with ring ribs are typically formed using hot forming methods, followed by machining. Heating is generally achieved through resistance furnaces, flames, or liquid media heating, but these methods suffer from low heating efficiency and high costs. The published patent application CN202211713568.9 proposes a high-frequency coil heating forming method and apparatus for titanium alloy ring rib parts, arguing that high-frequency induction heating offers advantages such as high speed, high thermal efficiency, and ease of control, significantly reducing heating time, saving energy, and improving production efficiency. However, during use, it was found that this forming method and apparatus cannot form a precise heating zone in the forming area, resulting in low energy efficiency, low heat utilization, and significant heat conduction losses due to the metal inner support rotating unit and forming wheel. This leads to defects such as surface damage, forming wrinkles, and post-forming springback deformation of the parts. Summary of the Invention

[0004] To address the above technical problems, this invention provides a method for forming high-strength titanium alloy ring-rib parts, which solves at least one of the following technical problems existing in the high-frequency coil heating forming method and forming device for titanium alloy ring-rib parts: (1) inability to form a precise heating area in the forming part; (2) low energy efficiency and low heat utilization rate; (3) large heat conduction loss of the inner support rotating unit and forming wheel; (4) defects such as damage and flanging forming wrinkles on the surface of the formed part; (5) many problems such as springback deformation of the formed part.

[0005] The objective of this invention is mainly achieved through the following technical solutions:

[0006] This invention provides a method for forming high-strength titanium alloy ring-ribbed parts, comprising the following steps:

[0007] Step S1: Unfold and cut the material into a titanium alloy strip blank according to the part size;

[0008] Step S2: Pre-form the cut titanium alloy strip blank into a ring shape;

[0009] Step S3: Perform thermal straightening on the preformed part;

[0010] Step S4: The preformed part is subjected to high-frequency induction heating rolling and flanging forming. The forming process includes three stages: semi-forming, full forming and re-pressing and straightening. The coupling forming gap Z during full forming is between 1.05t and 1.15t, where t is the wall thickness of the part.

[0011] Step S5: Laser 3D cutting is used to process the shape of the part to obtain the finished product;

[0012] Furthermore, in step S3, the thermal shaping involves fitting the preform onto a thermal expansion mold, then heating the thermal expansion mold to 650°C and holding it there for 1 hour. The thermal expansion mold expands the preform from the inside to the designed diameter.

[0013] Furthermore, step S4 includes the following sub-steps:

[0014] Step S4.1: Install the preformed part onto the high-frequency coil heating forming device;

[0015] Step S4.2: Start the high-frequency coil heating forming device to perform high-frequency induction heating rolling and flanging semi-forming on the pre-formed part;

[0016] Step S4.3: Continue running the high-frequency coil heating forming device to fully form the semi-formed part by high-frequency induction heating rolling and flanging.

[0017] Step S4.4: Continue running the high-frequency coil heating forming device to perform high-frequency induction heating rolling, flanging, and re-pressing on the fully formed part.

[0018] Furthermore, in step S4.1, the high-frequency coil heating forming device includes an inner support rotating unit 4, a high-frequency induction heating unit 5, and a forming wheel unit 6; the inner support rotating unit 4 opens the preform 3 from the inside and drives the preform 3 to rotate horizontally around a certain axis; the high-frequency induction heating unit 5 and the forming wheel unit 6 surround the outer side of the preform 3 ring; the high-frequency induction heating unit 5 and the preform 3 maintain a gap of about 8 to 10 mm; and the distance between the high-frequency induction heating unit 5 and the forming wheel unit 6 is 30 to 40 mm.

[0019] Furthermore, the inner support rotating unit 4 is made of high-temperature resistant and high-strength ceramic material.

[0020] Furthermore, the high-frequency induction heating unit 5 includes an induction coil 50 and two magnets 51. The induction coil 50 is rectangular, with a wide side length of 60mm and a long side length of 80mm. A magnet 51 is strung on each of the two wide sides of the induction coil 50. The magnets 51 are made of iron oxide and are cubic in shape, with dimensions of 20mm × 16mm × 16mm.

[0021] Furthermore, the forming wheel unit 6 includes a forming wheel 60, and there is an annular protrusion 601 on the edge of the forming wheel 60, the undulation radius of the annular protrusion 601 being 1.6 mm.

[0022] Furthermore, in step S4.2, when the forming wheel 60 feeds along the radial direction of the preform to 5 / 12 of the total feed stroke, the flange of the preform and the annular surface form an obtuse angle α, and the inner support rotary unit 4 drives the preform 3 to rotate the first revolution.

[0023] The total feed stroke is the sum of the part's flange width K and the radius of the chamfer 602 at the edge of the forming wheel 60.

[0024] Furthermore, in step S4.3, the forming wheel 60 is fed to the full radial direction of the preform 3. At this time, the distance between the annular protrusion 601 of the forming wheel 60 and the inner support rotary unit 4 is the coupling forming gap Z. At the same time, the annular surface of the preform 3 contacts the guide wheel 61 of the forming wheel unit 6, and the inner support rotary unit 4 drives the preform 3 to rotate a second revolution.

[0025] The total feed stroke is the sum of the part's flange width K and the radius of the chamfer 602 at the edge of the forming wheel 60; the coupling forming gap Z is between 1.05t and 1.15t, where t is the part's wall thickness.

[0026] Furthermore, in step S4.4, while maintaining the feed position of the forming wheel 60 in step S4.3, the inner support rotary unit 4 drives the preform 3 to rotate for the third revolution.

[0027] Compared with the prior art, the present invention can achieve at least one of the following technical effects:

[0028] (1) The present invention performs high-frequency induction heating rolling and flanging forming of preformed parts. The forming process includes three stages: semi-forming, full forming and re-pressing and straightening. The forming process is divided into three steps and a stable and gradual forming process is adopted to ensure that the high-strength titanium alloy gradually achieves the forming target under the withstandable deformation strength, avoiding the occurrence of material cracks and material damage caused by exceeding the metal's plasticity and toughness. In addition, the present invention reduces defects such as surface damage and flanging wrinkles of parts by designing a reasonable coupling forming gap Z size range, thereby improving the surface quality of parts. Furthermore, it can control the springback deformation of parts after forming, and the dimensions after forming are accurate.

[0029] (2) The present invention improves heating efficiency by using a high-frequency induction heating method with local magnetization, which can meet the temperature required for the forming position, and improves heating efficiency while reducing the heating area and reducing energy consumption.

[0030] (3) The present invention designs the material of the inner support rotating unit as a high temperature and high strength ceramic material, which greatly reduces the energy consumption of high frequency induction heating and reduces the heat loss through conduction, thereby improving the energy utilization rate of high frequency induction heating.

[0031] (4) The technical method of the present invention ensures stable and reliable heat output by setting a reasonable power of the induction heating unit and the rotation speed of the inner support rotation unit, and meets the requirement that the preformed part reaches the thermoforming temperature; by reasonably designing the spacing distribution between the high-frequency heating zone and the coupling forming zone, the occurrence of long-term overheating is avoided, and the time of exposure of the high-temperature preformed part to the air is greatly reduced, thereby effectively avoiding the risk of harmful impurities.

[0032] (5) The present invention designs a ring of protrusions on the forming surface of the forming wheel, which greatly reduces the contact area between the preform and the forming wheel, thereby reducing frictional resistance and heat loss.

[0033] (6) The present invention adopts a forming process with two sets of upper and lower parallel forming wheels, which realizes the simultaneous rolling forming of the two sides of the ring rib, thus improving the forming efficiency. Attached Figure Description

[0034] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0035] Figure 1 A three-dimensional schematic diagram of a high-strength titanium alloy ring-rib part;

[0036] Figure 2 This is a schematic diagram of the cross-section of a high-strength titanium alloy ring-rib part along the diameter direction.

[0037] Figure 3 This is a schematic diagram of a titanium alloy strip blank in plan view.

[0038] Figure 4 These are schematic diagrams of the front and left views of the preform;

[0039] Figure 5 A top view schematic diagram of the processing and assembly of a preformed part on a high-frequency coil heating forming device;

[0040] Figure 6 A front view schematic diagram of the machining and assembly of a preformed part on a high-frequency coil heating forming device;

[0041] Figure 7 This is a schematic diagram of the assembly of the induction coil and magnet in a high-frequency induction heating unit.

[0042] Figure 8 This is a schematic diagram of the front view and left view of the CC section of the forming wheel;

[0043] Figure 9 The starting position for roll forming and flanging of preforms Figure 5 A schematic diagram of the longitudinal section at point A in the middle;

[0044] Figure 10 For the preform rolling and flanging semi-forming process Figure 5 A schematic diagram of the longitudinal section at point A in the middle;

[0045] Figure 11 For the complete forming process of preform rolling and flanging Figure 5 A schematic diagram of the longitudinal section at point A in the middle;

[0046] Figure 12 These are schematic diagrams of the front view, top view, and left view of the BB section of the part.

[0047] In the diagram, 1-part; 1'-neutral layer of part; t-wall thickness of part; H-overall height of part; 10-ring surface; 11-flanged edge; K-flanged edge width; 12-joint section of ring surface; 13-positioning hole; 2-strip blank; 20-process allowance; 3-preform; 4-internal support rotary unit; 40-slider; 41-positioning pin; 42-hydraulic machinery; 5-high frequency induction heating unit; 50-induction coil; 51-Magnet; 6-Forming wheel unit; 60-Forming wheel; 601-Annular protrusion; 602-Forming wheel edge transition chamfer; 603-Shaft hole; 604-Circular boss; C-Section line; 61-Guide wheel; 62-Shaft; 63-Conical nut; 64-Slide; 65-Base; 66-Handwheel; A-Forming zone; α-Angle between the preform flange and the annular surface; Z-Coupling forming gap; B-Section line. Detailed Implementation

[0048] The following detailed description of a method for forming high-strength titanium alloy ring-rib type parts, with reference to specific embodiments, is provided. These embodiments are for comparative and illustrative purposes only, and the present invention is not limited to these embodiments.

[0049] Figure 1 This is a three-dimensional schematic diagram of a high-strength titanium alloy ring-rib part. Figure 2 This is a schematic diagram of the cross-section of a high-strength titanium alloy ring-rib part along the diameter direction.

[0050] For the aforementioned high-strength titanium alloy ring-rib parts, this invention proposes a forming method for high-strength titanium alloy ring-rib parts, comprising the following steps:

[0051] Step S1: Unfold and cut the material into a titanium alloy strip blank according to the part size;

[0052] Step S2: Pre-form the cut titanium alloy strip blank into a ring shape;

[0053] Step S3: Perform thermal straightening on the preformed part;

[0054] Step S4: The preformed part is subjected to high-frequency induction heating rolling and flanging forming. The forming process includes three stages: semi-forming, full forming and re-pressing and straightening. The coupling forming gap Z during full forming is between 1.05t and 1.15t, where t is the wall thickness of the part.

[0055] Step S5: Laser 3D cutting is used to process the shape of the formed part to obtain the finished product.

[0056] Specifically, in step S1, the ring rib part is a rotating part, and the diameter and height of the neutral layer 1' of the part are calculated according to the part size, based on the smallest outer diameter of the part, and then the part is unfolded and cut according to this size.

[0057] For example, the high-strength titanium alloy TA15 ring-shaped component 1 is a thin-walled annular structure with an outer diameter of Φ357.6-0.36mm, a wall thickness t of 1.5mm, and an overall height H of 50mm. Except for a section of the annular surface joint 12, the upper and lower ends of the remaining annular surface are flanged inwards. The annular surface and flanges are generally at right angles, with a transition chamfer of R3.75. Specifically, the arc length of the annular surface joint 12 is 100mm, and the height is 39mm. The width of the flange 11, excluding the wall thickness of the annular surface, is defined as the flange width K. The width K of the flanges 11 at both ends is 6.5mm. Except for the flanges at both ends, the remaining portion is an annular surface 10. The tensile strength σ of the high-strength titanium alloy TA15 is... b ≥935Mpa.

[0058] Based on the part dimensions, calculate the diameter and height of the neutral layer 1' of the part according to the smallest outer diameter of the part, and then unfold and cut the material according to these dimensions. For example, Φ355.74mm, the horizontal unfolding and cutting results in a titanium alloy strip blank 2 with a thickness of 1.5mm × length of 1117.6mm × width of 59.4mm. The middle part of the strip blank 2 is the annular surface 10 of the formed part, and the two sides are the flanges 11 of the formed part. A portion of the strip blank 2 is cut off from both ends and left in the middle, such as 20mm in length × 39mm in width, as the joint section 12 of the annular surface after forming. Apart from this part of the annular surface joint section 12, the remaining annular surface joint section 12 is used as a process allowance 20 and is located at both ends of the strip blank 2, 30mm at each end. Several round holes are evenly arranged on the centerline of the strip blank along the length direction for positioning holes 13 during flange forming, such as four Φ6.

[0059] It should be noted that in order to avoid quality defects caused by the tip effect of high frequency heating during the high frequency heating bending process, a process allowance of 20 is left at the beginning and end of the forming part of the preform. Figure 3 This is a schematic diagram of a titanium alloy strip blank.

[0060] In step S2, the strip blank 2 is deburred and then mechanically rounded. After rounding, a butt weld is performed, and the ring is manually argon arc welded into a closed ring structure with an outer diameter of Φ357.6mm and a height of 59.4mm.

[0061] In step S3, to completely eliminate the influence of the strip blank preforming process on the external dimensions, such as mechanical rounding and welding strain, and to ensure the roundness requirement of 0.3-0.5mm for the preformed part, hot straightening is required before flanging. Hot straightening involves fitting the preformed part onto a hot expansion mold, then heating the mold to 650℃ and holding it for 1 hour. The hot expansion mold expands the preformed part from the inside to the designed diameter, eliminating the out-of-roundness error of the preformed part's annular surface. It should be noted that the hot expansion mold is a cylindrical sleeve made of 316L stainless steel. Different linear expansion amounts for titanium alloy and stainless steel at 650℃ are calculated and designed. The preformed part is fitted onto the outer surface of the hot expansion mold sleeve, and the linear expansion amount of the hot expansion mold in a high-temperature environment rounds and straightens the preformed part. Figure 4 These are schematic diagrams of the front and left views of the preform.

[0062] Specifically, step S4 includes the following sub-steps:

[0063] Step S4.1: Install the preformed part onto the high-frequency coil heating forming device;

[0064] Step S4.2: Start the high-frequency coil heating forming device to perform high-frequency induction heating rolling and flanging semi-forming on the pre-formed part;

[0065] Step S4.3: Continue running the high-frequency coil heating forming device to fully form the semi-formed part by high-frequency induction heating rolling and flanging.

[0066] Step S4.4: Continue running the high-frequency coil heating forming device to perform high-frequency induction heating rolling, flanging, and re-pressing on the fully formed part.

[0067] Specifically, in step S4.1, the high-frequency coil heating forming device includes an inner support rotating unit 4, a high-frequency induction heating unit 5, and a forming wheel unit 6. The preform 3 is mounted on the inner support rotating unit 4, which expands the preform 3 from the inside to form a shape.

[0068] The inner support rotation unit 4 is a structural component with rotation and shaping functions, used to open the preform 3 from the inside and rotate it. It can adopt a structure commonly used in the prior art. In a specific embodiment, the inner support rotation unit 4 opens the preform 3 from the inside through the slider 40. The hydraulic mechanism 42 provides power for the movement of the slider 40. The positioning pin 41 on the inner support rotation unit 4 and the positioning hole 13 on the preform 3 cooperate for positioning. The inner support rotation unit 4 drives the preform 3 to rotate horizontally around a certain axis. The thickness and chamfer of the edge forming part where the inner support rotation unit 4 and the preform 3 contact each other match the inner cavity size of the formed part.

[0069] The high-frequency induction heating unit 5 includes an induction coil 50 and two magnets 51. The induction coil 50 includes a first arc-shaped segment, a straight segment, and a second arc-shaped segment connected in sequence. A magnet 51 is respectively installed on the first arc-shaped segment and the second arc-shaped segment. The high-frequency induction heating unit 5 is located outside the preform ring, with the straight segment parallel to the height direction of the preform ring surface. The two magnets 51 are located at the edges of the preform ring surface in the height direction. The heating surface formed by the induction coil 50 and the two magnets 51 maintains a gap of approximately 8-10 mm with the preform 3. The forming wheel unit 6 also surrounds the outside of the preform ring 3 and is close to the high-frequency induction heating unit 5. When the inner support rotation unit 4 drives the preform 3 to rotate horizontally, the preform 3 first passes through the high-frequency induction heating unit 5, and then passes through the forming wheel unit 6.

[0070] The forming wheel unit 6 includes a forming wheel 60, a guide wheel 61, a shaft 62, a conical nut 63, a slide 64, a base 65, and a handwheel 66. Specifically, the base 65 has a dovetail groove that engages with the slide 64. Under the push of the handwheel 66, the slide 64 can make a horizontal feed motion along the dovetail groove. The shaft 62 is fixed to the slide 64 by the conical nut 63. Two upper and lower symmetrical horizontal forming wheels 60 and a guide wheel 61 are radially mounted on the shaft 62. The longitudinal distance between the two upper and lower symmetrical horizontal forming wheels 60 is approximately equal to the total height H of the formed part. The guide wheel 61 is located in the middle of the two upper and lower symmetrical horizontal forming wheels 60. The maximum horizontal clearance between the forming wheel 60, the guide wheel 61 and the slide 64 is 0.07mm. If the clearance is too large, the forming accuracy will not meet the requirements. Although the clearance is very small, the two upper and lower symmetrical horizontal forming wheels 60 and guide wheels 61 can be passively and freely rotated, and can also move horizontally and linearly with the slide 64. That is, the two horizontal forming wheels 60 and guide wheels 61 can simultaneously approach the preform 3, or simultaneously move away from the preform 3. Figure 5 This is a schematic diagram of the machining and assembly of a preformed part on a high-frequency coil heating forming device. Figure 6 This is a front view schematic diagram of the preform being processed and assembled on a high-frequency coil heating forming device.

[0071] It should be noted that in steps S4.2 to S4.4, after the high-frequency coil heating forming device is started, the inner support rotating unit 4 drives the preform 3 to rotate horizontally at a uniform speed. During rotation, the preform 3 passes through the working area of ​​the high-frequency induction heating unit 5. The induction coil 50 forms a high-frequency induced magnetic field, and the alternating magnetic lines of force cut the titanium alloy preform, generating an induced electromotive force in the preform 3, thereby generating a high-frequency current. Since the titanium alloy has resistance, the preform 3 heats up instantaneously, thus forming a high-frequency induction heating phenomenon. Because the titanium alloy is a non-magnetic material, in order to improve the heating efficiency of the titanium alloy, two magnets 51 are embedded in the induction heating coil 50 for magnetization.

[0072] After the preform 3 is heated, it is rotated to the forming wheel unit 6. At this time, the forming wheel 60 moves horizontally and linearly to approach the preform 3, so that the preform 3 enters the coupling forming area formed by the upper and lower forming wheels 60 and the inner support rotating unit 4. The coupling forming area is the gap formed by the upper and lower forming wheels 60 and the inner support rotating unit 4, which finally enables the preform to achieve flanging forming.

[0073] Specifically, the induction coil 50 includes a first arc-shaped segment, a straight segment, and a second arc-shaped segment connected in sequence. The length of the arc-shaped segment corresponds to the length of the horizontal heating surface of the high-frequency induction heating area. The first and second arc-shaped segments correspond to the upper and lower flange forming areas of the preform. For example, if the length of the arc-shaped segment is 60mm, then the length of the heating surface is 60mm. A magnet 51 is strung on each of the two arc-shaped segments. The magnet 51 is composed of iron(III) oxide and is cubic in shape, such as 20mm × 16mm × 16mm. The function of the magnet is to... To improve the efficiency of electromagnetic induction heating, the length of the straight segment of the induction coil 50 corresponds to the vertical heating width of the upper and lower flanging forming areas. The length of the straight segment ensures that the two arc segments are exactly within the range of the upper and lower flanging forming areas of the preform. For example, if the length of the straight segment is 80mm, the vertical heating width of the upper and lower flanging forming areas is more than 12mm. The distance between the high-frequency induction heating unit 5 and the forming wheel unit 6 is 30-40mm, preferably 35mm. The rotation speed of the inner support rotation unit 4 is 1-3r / min, preferably 2r / min. Figure 7 This is a schematic diagram of the assembly of the induction coil and magnet in a high-frequency induction heating unit.

[0074] It should be noted that, on the one hand, the β transformation temperature of TA15 titanium alloy is 1050℃. If the high-frequency induction temperature exceeds the β transformation temperature of 1050℃, the titanium alloy material will exhibit β brittleness. That is, due to the temperature rise, the heating temperature of the α titanium alloy or (α+β) titanium alloy billet exceeds the (α+β) or β phase transformation point, resulting in the formation of coarse primary β grains and coarse Widmanstätten structure, reducing room temperature plasticity and toughness. Therefore, the upper limit of the high-frequency heating temperature is 1050℃.

[0075] On the other hand, the forming of high-strength titanium alloy sheet TA15 at room temperature is extremely difficult, and its σ b For materials with a strength ≥935 MPa, cold working flanging is not feasible. Only by heating TA15 to a temperature greater than 700 ± 30℃ can its maximum deformation resistance reach 598–430 MPa. Therefore, TA15 material must be heated to 680℃–730℃ and maintained at a stable temperature to meet the forming process requirements. Considering the approximately 1-second transition time between the preformed part and the forming zone, which results in a temperature loss of 70℃–80℃, the high-frequency induction forming temperature is set at 750℃–800℃ to ensure sufficient margin in the forming temperature.

[0076] Furthermore, titanium alloys exhibit high thermal chemical reactivity and are prone to oxidation under high-temperature conditions. They also readily adsorb harmful gaseous impurities such as hydrogen and nitrogen from the surrounding air, leading to oxide scale formation and surface saturation, resulting in reduced plasticity, increased hardness, and consequently, lower mechanical properties. Therefore, the hot forming of high-strength titanium alloy sheet TA15 requires a harmful impurity protection technology. First, the required energy is calculated based on the mass of the titanium alloy in the heating zone and the required heating temperature. Specifically, the mass of the titanium alloy in the heating zone depends on its length, width, thickness, and density; the required heating temperature is the temperature from room temperature to the aforementioned forming temperature of 750℃~800℃; the required energy is the product of the titanium alloy mass, the required heating temperature, and the titanium alloy's heat capacity. Then, the required heating time is calculated based on the required energy, the power of the high-frequency induction heating unit 5, and its energy utilization rate. Specifically, the required energy is divided by the power and energy utilization rate of the high-frequency induction heating unit 5 to obtain the heating time. Finally, the rotational speed of the inner support rotating unit 4 is calculated based on the heating time. Specifically, the rotational linear velocity is obtained by dividing the length of the heating zone by the heating time.

[0077] Specifically, the heating zone is 60mm long, the heating width of the upper and lower flange forming areas is 12mm, the preform thickness is 1.5mm, and the titanium alloy density is 4.51g / cm³. 3The heat capacity is 0.6 J / (g·℃), and the energy required to heat from 20℃ to 800℃ is 4560 J. If the power of the high-frequency induction heating unit 5 is 10KW and the energy utilization rate is 28.5%, then the heating time is 1.6 seconds. If the heating time is 1.6 seconds and the length of the heating area is 60 mm, then the linear velocity of rotation is 37.5 mm / s, and the corresponding rotation speed is 2 r / min.

[0078] In order to reduce the energy loss of the high-frequency induction heating unit 5 and improve the energy utilization rate, the material of the inner support rotating unit 4 is designed to be a high-temperature resistant and high-strength ceramic material, such as zirconium oxide and silicon nitride. In this way, the high-frequency induction heating unit 5 will not heat the non-metallic ceramic material. Moreover, the thermal conductivity of the ceramic material is low, and the amount of heat loss of the preform through the inner support rotating unit 4 will be reduced, thereby improving the energy utilization rate of the high-frequency induction heating unit 5.

[0079] Therefore, the technical method of the present invention ensures stable and reliable heat output by setting a reasonable power of the induction heating unit 5 and the rotation speed of the inner support rotation unit 4, and meets the requirement that the preform reaches the thermoforming temperature; by reasonably designing the spacing distribution between the high-frequency heating zone and the coupling forming zone, the occurrence of long-term overheating is avoided, and the time of exposure of the high-temperature preform to air is greatly reduced, thereby effectively avoiding the risk of harmful impurities.

[0080] Furthermore, while the high-frequency heating is in progress, the inner support rotary unit 4 drives the preform 3 to rotate horizontally at a constant speed. The upper and lower forming wheels 60 gradually feed along the radial direction of the preform. The heated forming parts at the upper and lower ends of the preform 3 are pressed into the coupling forming area formed by the forming wheels 60 and the inner support rotary unit 4 in two steps. As the number of rotations of the inner support rotary unit 4 increases, the preform is gradually rolled and flanged.

[0081] It should be noted that the roll forming area of ​​the preform 3 is a coupled forming zone formed by the horizontal torque applied by the inner support rotating unit 4 and the forming surface of the forming wheel 60. After high-frequency induction heating, the volume of the roll forming area of ​​the preform 3 expands. The relationship between the size of the preform after thermal expansion and the coupling forming gap Z is an important parameter of the forming process. The size of the coupling forming gap directly affects the roll forming size and surface quality. If the gap is too small, it will increase the frictional resistance of the forming surface, causing surface damage in the forming area and defects such as flanging wrinkles. If the gap is too large, it will increase the rebound after forming, and the springback deformation cannot be controlled, resulting in out-of-tolerance dimensions after forming. Therefore, after multiple process tests and calculations, the minimum coupling gap Z for the final fully formed roll forming hot forming was designed. min =1.05t, maximum coupling gap Z max =1.15t, where t is the wall thickness of the preform, that is, the wall thickness of the part.

[0082] Furthermore, to minimize frictional resistance during the forming process and reduce heat loss through conduction at the preform's rolling and flanging area via contact with the forming wheel 60, an annular protrusion 601 is designed within and closely adjacent to the edge transition chamfer 602 of the forming wheel 60. The radius of the annular protrusion 601 is 1.6 mm. After extrusion forming, only the annular protrusion 601 makes linear contact with the preform. The distance between the annular protrusion 601 and the inner support rotary unit 4 at this point is the coupling forming gap Z. This design significantly reduces the contact area between the preform and the forming wheel 60, thereby reducing frictional resistance and heat loss. Figure 8 The diagram shows the front view and left view of the CC section of the forming wheel. The forming wheel profile is stepped, and the outermost edge of the forming wheel profile is a transition chamfer with a radius of about 5 mm. Inside the profile, close to the edge transition chamfer, there is an annular protrusion 601. The maximum radius of the annular protrusion 601 is approximately the radius of the forming wheel minus the radius of the transition chamfer. The longitudinal section of the protrusion is semi-circular with a radius of 1.6 mm. Inward from the annular protrusion 601, there is a circular boss 604.

[0083] Specifically, in step S4.2, the forming wheel 60 is fed radially along the preform 3 until it contacts the surface of the preform 3, i.e., the starting position of the flanging forming of the preform. This position is set as the 0 point of the feed stroke of the forming wheel 60 along the radial direction of the preform. The sum of the part flanging width K and the radius of the chamfer 602 at the edge of the forming wheel 60 is set as the total feed stroke of the forming wheel 60 along the radial direction of the preform. When the forming wheel 60 feeds to 5 / 12 of the total feed stroke along the radial direction of the preform, the flanging of the preform and the annular surface form an obtuse angle α. The inner support rotary unit 4 drives the preform to rotate the first revolution, thereby achieving the semi-forming of the preform by rolling and flanging. Figure 9 The starting position for roll forming and flanging of preforms Figure 5 A schematic diagram of the longitudinal section at point A. Figure 10 For the preform rolling and flanging semi-forming process Figure 5 A schematic diagram of the longitudinal section of part A. It should be noted that during step S4.2, only the chamfer 602 of the edge transition of the forming wheel 60 contacts the surface of the preform 3, while the annular protrusion 601 does not contact the surface of the preform 3.

[0084] In step S4.3, the forming wheel 60 is fed to its full radial position along the preform, and the inner support rotary unit 4 drives the preform to rotate a second revolution, thus achieving complete roll forming of the preform. During this process, the distance between the annular protrusion 601 of the forming wheel 60 and the inner support rotary unit 4 is the coupling forming gap Z. At the same time, the annular surface of the preform 3 contacts the guide wheel 61 of the forming wheel unit 6, that is, the distance between the inner support rotary unit 4 and the guide wheel 61 is equal to the wall thickness t of the preform. The guide wheel 61 then passively rotates, thereby preventing the annular surface of the preform from being deformed by force when passing through the forming position. The guide wheel plays the role of supporting the annular surface of the preform 3 to maintain its shape. Figure 11 For the complete forming process of preform rolling and flanging Figure 5 A longitudinal cross-sectional view of part A. It should be noted that the diameter of the circular boss 604 on the forming wheel surface is equal to the diameter of the guide wheel 61. During step S4.3, when the forming wheel 60 has completed its full feed stroke, the circular boss 604 on the forming wheel surface and the guide wheel 61 simultaneously contact the surface of the preform 3.

[0085] It should be noted that the diameter of the forming wheel 60 is approximately 80 mm. The difference between the radius of the forming wheel 60 and the guide wheel 61, or the difference between the radius of the forming wheel 60 and the circular boss 604 on the forming wheel profile, is the sum of the total feed stroke of the forming wheel 60 along the radial direction of the preform and the wall thickness t of the preform. That is, the diameter of the guide wheel 61 and the diameter of the circular boss 604 on the forming wheel profile depend on the diameter of the forming wheel 60, the total feed stroke of the forming wheel 60, and the wall thickness t of the preform.

[0086] In step S4.4, the feed position of the forming wheel 60 in step S4.3 is maintained, and the re-pressing and shaping are performed. The inner support rotation unit 4 drives the preform to rotate for the third time to eliminate springback deformation.

[0087] Specifically, in step S5, after forming, laser three-dimensional cutting is used to remove the process allowance 20, thereby obtaining a qualified finished product without cracks or overheating defects. Figure 12 These are schematic diagrams of the front view, top view, and left view of the BB section of the cut and machined part.

[0088] Example

[0089] A thin-walled annular structural component 1, made of TA15 high-strength titanium alloy, has an outer diameter of Φ357.6-0.36mm. The component has a wall thickness t of 1.5mm and an overall height H of 50mm. Except for a section of the annular surface joint 12, the upper and lower ends of the remaining annular surface are flanged inwards. The annular surface and flanges are generally at right angles, with a chamfer of R3.75. Specifically, the arc length of the annular surface joint 12 is 100mm, and the height is 39mm. The width of the flange 11 (excluding the wall thickness of the annular surface) is defined as the flange width K. The width K of the flanges 11 at both ends is 6.5mm. Except for the flanges at both ends, the remaining portion is an annular surface 10. The tensile strength σ of the high-strength titanium alloy TA15 is... b ≥935Mpa.

[0090] The forming method for high-strength titanium alloy ring-ribbed parts includes the following steps:

[0091] Step S1: Unfold and cut the material into a titanium alloy strip blank according to the part size;

[0092] Based on the smallest outer diameter of the part, the diameter of the neutral layer of the part is calculated to be Φ355.74mm. The horizontally unfolded blank is a titanium alloy strip blank 2 with a thickness of 1.5mm × length of 1117.6mm × width of 59.4mm. The two ends of the strip blank 2 are cut off and left with a length of 20mm × width of 39mm. In addition, a process allowance of 30mm is left at the beginning and end of the forming part.

[0093] Step S2: Pre-form the cut titanium alloy strip blank into a ring shape;

[0094] After deburring, the strip blank 2 is mechanically rounded and then butt-welded. The butt weld is then performed using manual argon arc welding to form a closed ring structure with an outer diameter of Φ357.6mm and a height of 59.4mm.

[0095] Step S3: Perform thermal straightening on the preformed part;

[0096] By heating the thermal expansion mold to 650℃ and holding it at that temperature for 1 hour, the expansion mold will expand the preform from the inside to a round shape, and the roundness of the preform is 0.4mm.

[0097] Step S4: The preform is formed by high-frequency induction heating and rolling.

[0098] Step S4.1: Install the preformed part on the high-frequency coil heating forming device;

[0099] The high-frequency coil heating forming device includes an inner support rotating unit 4, a high-frequency induction heating unit 5, and a forming wheel unit 6. The inner support rotating unit 4 is made of zirconia ceramic. The high-frequency induction heating unit 5 is located outside the preform ring, maintaining a gap of approximately 10mm with the preform 3. The high-frequency induction heating unit 5 includes an induction coil 50 and two magnets 51. The induction coil 50 is roughly rectangular, with a width of 60mm, corresponding to a horizontal length of 60mm for the high-frequency induction heating area. A magnet 51 is strung on each of the two widths. The magnets 51 are composed of iron oxide (Fe3O4) and are cubic in shape, with dimensions of 20mm × 16mm × 16mm. The length of the rectangular induction coil 50 is 80mm, corresponding to a vertical heating width of 12mm for each of the upper and lower flange forming areas. The distance between the high-frequency induction heating unit 5 and the forming wheel unit 6 is 35mm. The radius of the chamfer 602 at the edge of the forming wheel 60 in the forming wheel unit 6 is 5.5 mm. Inside the chamfer 602 at the edge of the forming wheel 60, close to the chamfer, there is a ring-shaped protrusion 601 with a radius of 1.6 mm. Inward from the ring-shaped protrusion 601 is a circular boss 604 with a diameter of 53 mm. The guide wheel has a diameter of 53 mm.

[0100] Step S4.2: Start the high-frequency coil heating forming device to perform high-frequency induction heating rolling and flanging semi-forming on the pre-formed part;

[0101] The rotation speed of the inner support rotary unit 4 is 2 r / min. The forming wheel 60 is fed 5 mm along the radial direction of the preform to the position of 5 / 12 of the total feed stroke. At this time, the outer contour of the forming wheel 60 contacts the flange part of the preform, so that the flange of the preform and the ring surface form an obtuse angle of 154°. The inner support rotary unit 4 drives the preform to rotate the first revolution, so that the preform achieves the rolling flange semi-forming.

[0102] Step S4.3: Continue running the high-frequency coil heating forming device to fully form the semi-formed part by high-frequency induction heating rolling and flanging.

[0103] The forming wheel 60 is fed 12mm radially along the preform, completing the full feed stroke. At this point, the coupling forming zone gap Z is 1.65mm, which is within the minimum coupling gap Z. min 1.575mm and maximum coupling gap Z max Between 1.725mm, the annular surface of the preform 3 contacts the guide wheel 61 of the forming wheel unit 6, and the guide wheel 61 then rotates passively. The inner support rotation unit 4 drives the preform to rotate a second time, thus realizing the complete forming of the preform by rolling and flanging.

[0104] Step S4.4: Continue running the high-frequency coil heating forming device to perform high-frequency induction heating rolling, flanging, and re-pressing on the fully formed part;

[0105] While maintaining the feed position of the forming wheel 60 in step S4.3, the inner support rotary unit 4 drives the preform to rotate for the third revolution to eliminate springback deformation.

[0106] Step S5: Laser 3D cutting is used to process the shape of the formed part to obtain the finished product.

[0107] Laser 3D cutting is used to remove 20% of the process allowance. The parts are free of cracks, surface damage, folding and wrinkles, etc. After forming, the parts are free of springback deformation, have accurate dimensions, and are qualified finished products without overheating quality defects. The energy utilization rate is 30%.

[0108] Comparative Example 1

[0109] The same parts, materials, equipment, and process steps are used as in the embodiment, except that in step S4.3, after the forming wheel 60 has completed its full feed stroke, the coupling forming zone gap Z is 1.5 mm, which is less than the minimum coupling gap Z. min The thickness of 1.575mm ultimately caused surface damage to the forming area and wrinkles during the flanging process.

[0110] Comparative Example 2

[0111] The same parts, materials, equipment, and process steps are used as in the embodiment, except that in step S4.3, after the forming wheel 60 has fully fed to its position, the gap Z of the coupling forming zone is 1.5 mm, which is greater than the maximum coupling gap Z. max The 1.725mm difference ultimately resulted in increased springback after forming, making it impossible to control the springback deformation. Consequently, the overall height H of the formed part was 50.2mm, exceeding the dimensional tolerance.

[0112] Comparative Example 3

[0113] The parts are of the same size as those in the embodiment, using the same materials, equipment, and process steps. The difference is that in step S4, the parts are formed in one step, and cracks eventually appear in the flanged area of ​​the forming zone, with a large dimensional springback.

[0114] Comparative Example 4

[0115] The same parts, materials, equipment and process steps as in the embodiment are used. The difference is that in step S4.1, the high-frequency induction heating unit 5 does not include two magnets 51. The same inner support rotating unit 4 is used with a rotation speed of 2r / min. The heating area is wide, the heat cannot be concentrated, the heating temperature does not meet the requirements, the forming temperature is not high enough, and it cannot be formed. Reducing the rotation speed of the inner support rotating unit 4 to 1r / min can barely form the part, but it greatly reduces the forming efficiency.

[0116] Comparative Example 5

[0117] The same size parts, materials, equipment and process steps as in the embodiment are used. The difference is that in step S4.1, a ring-shaped protrusion is not set on the forming surface of the forming wheel. This requires increasing the rotation drive power of the original inner support rotation unit 4, which increases heat loss during forming and ultimately leads to reduced forming efficiency and increased energy consumption.

[0118] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for forming high-strength titanium alloy ring-rib type parts, characterized in that, The method includes the following steps: Step S1: Unfold and cut the material into a titanium alloy strip blank according to the part size; Step S2: Pre-form the cut titanium alloy strip blank into a ring shape; Step S3: Perform thermal straightening on the preformed part; Step S4: The preformed part is subjected to high-frequency induction heating rolling and flanging forming. The forming process includes three stages: semi-forming, full forming and re-pressing and straightening. The coupling forming gap Z during full forming is between 1.05t and 1.15t, where t is the wall thickness of the part. Step S5: Laser 3D cutting is used to process the shape of the part to obtain the finished product; Step S4 includes the following sub-steps: Step S4.1: Install the preformed part on the high-frequency coil heating forming device; the high-frequency coil heating forming device includes an inner support rotation unit (4), a high-frequency induction heating unit (5) and a forming wheel unit (6), the forming wheel unit (6) includes a forming wheel (60); Step S4.2: Start the high-frequency coil heating forming device to perform high-frequency induction heating rolling and flanging semi-forming on the pre-formed part; Step S4.3: Continue running the high-frequency coil heating forming device to fully form the semi-formed part by high-frequency induction heating rolling and flanging. Step S4.4: Continue running the high-frequency coil heating forming device to perform high-frequency induction heating rolling, flanging, and re-pressing on the fully formed part; In step S4.3, the forming wheel (60) is fed to the full position along the radial direction of the preform (3). At this time, the distance between the annular protrusion (601) of the forming wheel (60) and the inner support rotary unit (4) is the coupling forming gap Z. At the same time, the annular surface of the preform (3) contacts the guide wheel (61) of the forming wheel unit (6). The inner support rotary unit (4) drives the preform (3) to rotate for the second time. The full feed stroke is the sum of the part flange width K and the radius of the edge transition chamfer (602) of the forming wheel (60).

2. The method according to claim 1, characterized in that, In step S3, the hot shaping involves fitting the preform onto a hot expansion mold, then heating the hot expansion mold to 650°C and holding it at that temperature for 1 hour. The hot expansion mold expands the preform from the inside to the designed diameter.

3. The method according to claim 1, characterized in that, In step S4.1, the inner support rotation unit (4) opens the preform (3) from the inside and drives the preform (3) to rotate horizontally around a certain axis. The high-frequency induction heating unit (5) and the forming wheel unit (6) surround the outer side of the preform (3) ring. The high-frequency induction heating unit (5) and the preform (3) maintain a gap of about 8 to 10 mm. The distance between the high-frequency induction heating unit (5) and the forming wheel unit (6) is 30 to 40 mm.

4. The method according to claim 1, characterized in that, The inner support rotating unit (4) is made of high-temperature resistant and high-strength ceramic material.

5. The method according to claim 1, characterized in that, The high-frequency induction heating unit (5) includes an induction coil (50) and two magnets (51). The induction coil (50) is rectangular, with a width of 60 mm and a length of 80 mm. A magnet (51) is strung on each of the two widths of the induction coil (50). The magnets (51) are made of iron(III) oxide and are cubic in shape with dimensions of 20 mm × 16 mm × 16 mm.

6. The method according to claim 1, characterized in that, There is an annular protrusion (601) on the edge of the forming wheel (60), and the radius of the annular protrusion (601) is 1.6 mm.

7. The method according to claim 1, characterized in that, In step S4.2, when the forming wheel (60) feeds along the radial direction of the preform to 5 / 12 of the total feed stroke, the flange of the preform and the annular surface form an obtuse angle α, and the inner support rotary unit (4) drives the preform (3) to rotate for the first revolution. The total feed stroke is the sum of the part flange width K and the radius of the chamfer (602) at the edge of the forming wheel (60).

8. The method according to claim 1, characterized in that, In step S4.4, the feed position of the forming wheel (60) in step S4.3 is maintained, and the inner support rotation unit (4) drives the preform (3) to rotate for the third revolution.

Images