A method and apparatus for electrothermal stretch bending of titanium alloy Y-shaped profiles

Abstract

This invention belongs to the field of metal forming technology, specifically relating to a method and apparatus for electrothermal bending of titanium alloy Y-shaped profiles. The electrothermal bending apparatus includes an upper clamping plate and a lower clamping plate supporting the Y-shaped profile cross-section; upper and lower series plates connect multiple upper and lower filler blocks to form a covering surface; a conductive clamp holds the Y-shaped profile and is connected to an electrode; a fixing block connects to the upper and lower series plates and is connected to an electrode, the fixing block being insulated from the Y-shaped profile contact surface and having a conductive structure with the upper and lower series plates to achieve electrical energy conduction and heating. This simple structure effectively controls the distortion of the Y-shaped profile cross-section during electrothermal bending, is suitable for forming complex Y-shaped titanium alloy profiles, and ensures uniform forming temperature and cross-sectional quality.

Description

Technical Field

[0001] This invention belongs to the field of metal forming technology, specifically relating to a method and apparatus for electrothermal bending forming of titanium alloy Y-shaped profiles. Background Technology

[0002] Titanium alloy Y-profile bent components play a crucial load-bearing and sealing role in aircraft, and their forming quality directly affects the aircraft's assembly accuracy, service life, and sealing performance. Electrothermal stretch bending technology has become one of the main methods for effectively forming titanium alloy Y-profiles. However, due to the complex cross-section of titanium alloy Y-profiles, traditional processes are insufficient for their stretch bending forming, presenting several technical challenges. Specifically, the following difficulties exist:

[0003] 1. Surface accuracy: The complexity of the overhanging airfoil and the springback law poses a challenge to surface accuracy. The overhanging airfoil may collapse, failing to cover the part dimensions, thus affecting the function and performance of the part.

[0004] 2. Cross-sectional distortion: Since some surfaces are constrained by the mold, conventional methods for cantilevered wing plates cannot effectively constrain them, and methods such as flexible support need to be considered to solve the problem of cross-sectional distortion.

[0005] 3. Tendency to crack at the root of the flange: During the bending process, the influence of lateral forces may cause cracks at the root of the flange, and effective control methods are needed to prevent this cracking phenomenon.

[0006] 4. Poor temperature uniformity: Due to the uneven temperature change after the surface comes into contact with the mold, the temperature of the suspended wing plate is relatively high, making temperature uniformity control a difficult problem.

[0007] The existing technologies mainly focus on the following two aspects:

[0008] 1. For example Figure 1 The conductive clamp device for bending extruded Y-profiles: It uses a clamp block assembly to completely cover the Y-profile and uses a limiting structure to prevent the Y-profile from moving, so as to achieve effective constraint on the extruded Y-profile.

[0009] 2. For example Figure 2 A tension bending die for extruded Y-shaped profiles: using multiple shaped steel plates and rolled inner arc liner plates, the die can cover the inner arc section of the titanium alloy Y-shaped profile, solving the problem of unconstrained section.

[0010] However, existing technologies still have shortcomings:

[0011] 1. There is a lack of overall consideration for the control of distortion and temperature uniformity of the electrothermal bending section of titanium alloy Y-profiles, and a more comprehensive solution is needed.

[0012] Therefore, there is an urgent need to make breakthroughs in the research and development of key technologies such as temperature uniformity control and distortion control of electrothermal bending forming sections for complex Y-shaped cross-section titanium alloy profiles. Summary of the Invention

[0013] (a) Technical problems to be solved

[0014] This invention addresses the above-mentioned problems by proposing a method and apparatus for electrothermal bending of titanium alloy Y-shaped profiles. The purpose is to solve the problems of insufficient control over cross-sectional distortion and temperature uniformity during the electrothermal bending process of titanium alloy Y-shaped profiles.

[0015] (II) Technical Solution

[0016] To achieve the above objectives, the first aspect of the present invention provides an electrothermal stretch bending forming apparatus for titanium alloy Y-profiles, comprising:

[0017] The upper and lower clamping plates are used to support the Y-shaped profile section;

[0018] Upper series plate and lower series plate;

[0019] Multiple upper filling blocks and multiple lower filling blocks are connected together by the upper series plate to form an upper covering surface, and multiple lower filling blocks are connected together by the lower series plate to form a lower covering surface;

[0020] A conductive chuck, wherein the conductive chuck is used to hold the Y-profile and is connected to an electrode; and

[0021] A fixing block is used to fix the upper series plate and the lower series plate and connect to the second electrode. The surface of the fixing block that contacts the Y-shaped material is an insulating surface, and there is a conductive structure between the fixing block and the upper and lower series plates, so that when energized, the fixing block can conduct electrical energy to the upper and lower series plates and cause them to heat up.

[0022] Furthermore, the upper filling block and the upper clamping plate are slidably disposed relative to each other; the lower filling block and the lower clamping plate are slidably disposed relative to each other.

[0023] Furthermore, the outer surface of the fixing block and the part in contact with the Y-shaped material are treated with insulating spraying to insulate them from each other.

[0024] Furthermore, the upper filling block has an upper serial port that allows the upper serial plate to pass through, so that multiple upper filling blocks are connected as one unit. The lower filling block has a lower serial port that allows the lower serial plate to pass through, so that multiple lower filling blocks are connected as one unit. The upper serial plate and the upper filling block are relatively slidably arranged, and the lower serial plate and the lower filling block are relatively slidably arranged.

[0025] Furthermore, insulating spraying is applied between the upper series plate and the upper filler block, and between the lower series plate and the lower filler block.

[0026] Furthermore, the surfaces of the upper and lower filler blocks are treated with insulating spray coating.

[0027] To achieve the above objectives, a second aspect of the present invention provides a method for forming a titanium alloy Y-profile using the aforementioned electrothermal bending forming apparatus, the method comprising the following steps:

[0028] In the Y-shaped electrothermal bending forming device, the sliding friction gap and lubrication conditions between the upper and lower filler blocks and the upper and lower clamping plates are set to accommodate thermal expansion and reduce friction.

[0029] The dimensions of the upper and lower filler blocks are designed according to the required bending curvature characteristics of the Y-shaped profile, and multiple upper and lower filler blocks are connected into one piece by upper and lower connecting plates to form a corresponding support surface.

[0030] Install the Y-shaped profile between the upper and lower clamping plates and secure it with conductive clamps;

[0031] When heated by electricity, electrical energy is transferred to the upper and lower series plates through the conductive structure of the fixed block, causing the upper and lower series plates to act as heating elements and generate heat. The heat is then conducted to heat multiple upper and lower filling blocks.

[0032] At the same time, the Y-shaped profile is directly heated by electricity to ensure its overall temperature uniformity;

[0033] The Y-profile is pre-stretched to the yield state under heating conditions;

[0034] Maintain the axial pre-tension state and perform stretch bending forming operation on the Y profile until the desired profile shape is achieved;

[0035] After the stretch bending is completed, the Y-profile is subjected to additional stretch deformation and held at a certain temperature for a certain period of time to perform stress relaxation;

[0036] After forming, the profile is unloaded, and a 3D scanner is used to inspect and evaluate the accuracy of the Y-profile electrothermal bending forming.

[0037] Furthermore, during the bending process, a non-contact infrared thermometer is used to monitor the temperature of the upper series plate, the lower series plate, and the Y-shaped profile.

[0038] Furthermore, the upper and lower series plates are heated, and the temperature is controlled within the range of 500-700℃.

[0039] Furthermore, the Y-shaped profile is electrically heated, and the temperature is controlled within the range of 700-800℃.

[0040] (III) Beneficial Effects

[0041] This invention provides a method and apparatus for electrothermal bending of titanium alloy Y-shaped profiles. By employing a fixed block with a conductive structure and multiple upper and lower filler blocks, it achieves comprehensive control over cross-sectional distortion and temperature uniformity during the electrothermal bending process of the Y-shaped profile. The conductive structure conducts electrical energy, causing the upper and lower series plates to act as heating elements. This heat conduction heats the multiple filler blocks, resulting in uniform heating of the Y-shaped profile. Through pre-stretching, bending, supplementary stretching, and stress relaxation, this method ensures complete fit between the Y-shaped profile and the mold, ultimately achieving high-precision Y-shaped profile forming. Compared to existing technologies, the method and apparatus of this invention achieve significant technological advancements in controlling cross-sectional distortion and temperature uniformity, improving forming accuracy and efficiency, while also offering a simple tooling structure and low cost. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of a special clamping device for bending extruded Y-shaped profiles, disclosed in the prior art.

[0043] Figure 2 This is a schematic diagram of a tension bending die structure for extruded Y-shaped profiles, disclosed in the prior art.

[0044] Figure 3 This is a schematic diagram of the principle of electrothermal stretch bending forming of a complex Y-section titanium alloy profile disclosed in this application.

[0045] Figure 4 This is a schematic diagram of a temperature uniformity control principle disclosed in this application.

[0046] Figure 5 This is a three-dimensional structural diagram of a filling block disclosed in this application.

[0047] Figure 6 This is a schematic diagram of an assembly structure of a combined mold and a filler block disclosed in this application.

[0048] Figure 7 This is a schematic diagram of the assembly structure of a filler block disclosed in this application.

[0049] Figure 8 This is a schematic diagram of a discrete filler block structure designed based on the curvature characteristics of a part, as disclosed in this application.

[0050] Figure 9 The simulation results of the temperature field and cross-sectional distortion of a titanium alloy Y-shaped profile under electrothermal stretch bending are disclosed in this application.

[0051] The reference numerals in the figure are as follows: 1. Upper clamping plate; 2. Lower clamping plate; 3. Upper filling block; 4. Lower filling block; 5. Fixing block; 6. Conductive clamp; 7. Upper series block; 8. Lower series block; 9. Y-shaped profile. Detailed Implementation

[0052] The present invention will now be described in detail with reference to the accompanying drawings, and the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or may have a component in between. When a component is considered "connected to" another component, it can be directly connected to the other component or may have a component in between. When a component is considered "set on" another component, it can be directly set on the other component or may have a component in between. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0055] Please see Figures 3-8 The image shown is a schematic diagram of a titanium alloy Y-shaped profile electrothermal bending forming device provided in a preferred embodiment of this application. Figures 3-8 In the illustrated embodiment, the device includes:

[0056] The main function of the upper clamping plate 1 and the lower clamping plate 2 is to support the suspended wing plate and control defects such as cross-sectional distortion during the bending process.

[0057] The upper series plate 7 and the lower series plate 8 serve to connect multiple upper filler blocks 3 and lower filler blocks 4. The upper series plate 3 and the lower series plate 4 are similar to heating rods. After being electrically heated, they are heated to each discrete filler block through heat conduction, which ultimately achieves uniform control of bending temperature. This helps the stability and coordinated operation of the overall structure.

[0058] Multiple upper filling blocks 3 and multiple lower filling blocks 4 are connected together by the upper series plate 7 to form an upper covering surface, and multiple lower filling blocks 4 are connected together by the lower series plate 8 to form a lower covering surface, so as to cover the cross section of the Y profile 9.

[0059] The conductive chuck 6's main function is to clamp the Y-shaped profile and conduct electrical energy through its connection with electrode one.

[0060] The fixing block 5 serves to fix the upper series plate 7 and the lower series plate 8, and to conduct electrical energy through its connection with the second electrode. The surface of the fixing block 5 and the part in contact with the Y-shaped material 9 are insulating surfaces to prevent electrical energy from being conducted to the surface of the Y-shaped material 9. Furthermore, the fixing block 5 has a conductive structure with the upper series plate 7 and the lower series plate 8, so that after being energized, the fixing block 5 can conduct electrical energy to the upper series plate 7 and the lower series plate 8 and cause them to heat up.

[0061] This device integrates all the aforementioned components and, through a rational design and structural layout, achieves comprehensive heating and deformation control of the Y-shaped profile 9, thereby solving the problems of cross-sectional distortion and temperature uniformity control. In practical applications, this device improves the accuracy and efficiency of electrothermal bending forming of titanium alloy Y-shaped profiles 9.

[0062] In some embodiments, the upper filling block 3 and the upper clamping plate 1 are relatively slidably disposed; the lower filling block 4 and the lower clamping plate 2 are relatively slidably disposed, that is, during the forming process, the contact surfaces of the two slide relative to each other.

[0063] The outer surface of the fixing block 5 and the parts in contact with the Y-profile 9 are treated with an insulating spray coating to ensure insulation between them. The insulating spray coating can be applied using a material with good insulating properties, such as insulating varnish or a rubber coating, to form an electrical insulating layer. This treatment effectively prevents current from being conducted through the fixing block to the Y-profile 9.

[0064] In the structure of the electrothermal bending forming device, the upper filling block 3 and the lower filling block 4 are components used to cover the cross-section of the Y-shaped profile 9. These filling blocks form an upper covering surface and a lower covering surface through their connection with the upper connecting plate 7 and the lower connecting plate 8. Specifically, each upper filling block 3 has an upper connecting port through which the upper connecting plate 7 passes, connecting multiple upper filling blocks 3 into one unit. Similarly, each lower filling block 4 has a lower connecting port through which the lower connecting plate 8 passes, connecting multiple lower filling blocks 4 into one unit.

[0065] This design allows the upper filler block 3 and lower filler block 4 to achieve overall integration while forming the covering surface, through the connection of the upper series plate 7 and lower series plate 8. Simultaneously, the upper series plate 7 and upper filler block 3, and the lower series plate 8 and lower filler block 4, are relatively slidingly arranged. This allows for a certain degree of sliding freedom between the upper filler block 3 and lower filler block 4 and their respective series plates during the electrothermal bending forming process.

[0066] The relative sliding setting helps to better adapt to the deformation of the Y-profile 9 during the stretch bending process, reduces stress concentration caused by deformation, and helps to improve the forming accuracy and avoid defects.

[0067] In the structure of the electrothermal bending forming device, the contact surfaces between the upper series plate 7 and the upper filler block 3, and between the lower series plate 8 and the lower filler block 4, are treated with insulating spraying. The purpose of this treatment is to prevent electrical energy from being conducted to the filler block during the bending forming process, thereby ensuring the insulation between the Y-profile 9 and the series plates.

[0068] In this specific design, insulating spraying is applied to the surfaces of the upper filler block 3 and the lower filler block 4, and this treatment plays a key role in the stability of the forming process.

[0069] A second aspect of the present invention provides a method for forming a titanium alloy Y-profile using the aforementioned electrothermal bending forming apparatus, the method comprising the following steps:

[0070] In the Y-shaped profile electrothermal bending forming device, the sliding friction gap and lubrication conditions between the upper filling block 3, the lower filling block 4 and the upper clamping plate 1 and the lower clamping plate 2 are set to adapt to thermal expansion and reduce friction.

[0071] The dimensions of the upper filler block 3 and the lower filler block 4 are designed according to the required bending curvature characteristics of the Y-shaped profile, and multiple upper filler blocks 3 and lower filler blocks 4 are connected into one piece by the upper connecting plate 7 and the lower connecting plate 8 to form the corresponding support surface;

[0072] Install the Y-shaped profile 9 so that it is positioned between the upper clamping plate 1 and the lower clamping plate 2, and fix it with the conductive clamp 6;

[0073] When heated by electricity, electrical energy is transferred to the upper series plate 7 and the lower series plate 8 through the conductive structure of the fixed block 5, so that the upper series plate 7 and the lower series plate 8 act as heating elements and generate heat, thereby heating multiple upper filling blocks 3 and lower filling blocks 4 through heat conduction.

[0074] At the same time, the Y-shaped profile 9 is directly heated by electricity to ensure its overall temperature uniformity;

[0075] The Y-profile 9 is pre-stretched to the yield state under heating;

[0076] Maintain the axial pre-tension state and perform a stretch bending forming operation on the Y-profile 9 until the desired profile shape is achieved;

[0077] After the stretch bending is completed, the Y-profile 9 is subjected to additional stretch deformation and held at a certain temperature for a certain period of time to perform stress relaxation;

[0078] After forming, the profile is unloaded, and a 3D scanner is used to inspect and evaluate the accuracy of the Y-profile electrothermal bending forming.

[0079] During the stretch bending process, a non-contact infrared thermometer is used to monitor the temperature of the upper series plate 7, the lower series plate 8, and the Y-profile 9. In addition, the upper series plate 7 and the lower series plate 8 are heated, with the temperature controlled within the range of 500-700℃. Simultaneously, the Y-profile 9 is electrically heated, with the temperature controlled within the range of 700-800℃. These steps help ensure precise temperature control throughout the forming process to meet the forming requirements.

[0080] Understandably, the verification process of this method first involves designing and manufacturing a tension bending forming fixture suitable for TC4 titanium alloy profiles with Y-shaped cross-sections. Before forming, the billet is treated with anti-oxidant and lubricant spraying, while the surface of the tension bending die is sprayed with an insulating and heat-insulating coating and lubricant. Subsequently, the die and conductive chuck 6 are installed and the horizontal height is adjusted. The billet is clamped into the die, the initial position is adjusted, and then the discrete upper filler block 3 and lower filler block 4 are installed and fixed. The upper series plate 7 and lower series plate 8 are electrically heated to 500-700℃, and the temperature is monitored using a non-contact infrared thermometer. Subsequently, the billet is electrically heated to 700-800℃. After pre-stretching to the yield state, the axial pre-stretch state is maintained for tension bending forming. After completion, additional stretching deformation and stress relaxation are performed. Finally, the power is turned off and the part is unloaded. The forming accuracy is measured and evaluated using a 3D scanner to verify the effectiveness and feasibility of the electrothermal tension bending forming method proposed in this application. Figure 9 The simulation results of temperature field and cross-sectional distortion of titanium alloy Y-shaped material during electrothermal stretch bending are shown in the figure.

[0081] The electrothermal stretch bending forming method proposed in this embodiment achieves efficient forming of Y-shaped TC4 titanium alloy profiles through reasonable process steps and equipment design. Techniques such as spraying anti-oxidant and lubricant, applying heat insulation and lubrication coatings, and using a non-contact infrared thermometer effectively improve the smoothness and accuracy of the forming process. Electric heating ensures uniform heating of the billet, upper filler block, and lower filler block, guaranteeing the plasticity and adaptability of the Y-shaped profile during stretch bending. Pre-stretching, supplementary stretching, and stress relaxation steps further guarantee the stability and forming quality of the parts. Verification results of the entire method show that this technical solution has achieved beneficial effects in practical applications, improving forming accuracy, reducing uncertainties in the forming process, and laying a solid foundation for the production of high-quality Y-shaped TC4 titanium alloy profiles.

[0082] Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this application is defined by the appended claims rather than the foregoing description, and all variations falling within the meaning and scope of equivalents of the claims are intended to be embraced within this application. No reference numerals in the claims should be construed as limiting the scope of the claims. Furthermore, it is clear that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. Multiple units or devices recited in the apparatus claims may also be implemented by the same unit or device in software or hardware. The terms "first," "second," etc., are used to indicate names and do not indicate any particular order.

[0083] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the spirit and scope of the technical solutions of this application.

Claims

1. A device for electrothermal bending forming of titanium alloy Y-shaped profiles, characterized in that, include: The upper and lower clamping plates are used to support the Y-shaped profile section; Upper series plate and lower series plate; Multiple upper filling blocks and multiple lower filling blocks are connected together by the upper series plate to form an upper covering surface, and multiple lower filling blocks are connected together by the lower series plate to form a lower covering surface; A conductive chuck, wherein the conductive chuck is used to hold the Y-profile and is connected to an electrode; and A fixing block is used to fix the upper series plate and the lower series plate and connect them to the second electrode. The surface of the fixing block that contacts the Y-shaped material is an insulating surface, and there is a conductive structure between the fixing block and the upper and lower series plates, so that when energized, the fixing block can conduct electrical energy to the upper and lower series plates and cause them to heat up.

2. The electrothermal bending forming device for titanium alloy Y-shaped profiles according to claim 1, characterized in that, The upper filling block and the upper clamping plate are slidably arranged relative to each other; the lower filling block and the lower clamping plate are slidably arranged relative to each other.

3. The electrothermal bending forming device for titanium alloy Y-shaped profiles according to claim 1, characterized in that, The outer surface of the fixing block and the parts in contact with the Y-shaped material are treated with insulating spray coating to insulate them from the Y-shaped material.

4. The electrothermal bending forming device for titanium alloy Y-shaped profiles according to claim 1, characterized in that, The upper filling block has an upper serial port that allows the upper serial plate to pass through, so that multiple upper filling blocks are connected as one unit. The lower filling block has a lower serial port that allows the lower serial plate to pass through, so that multiple lower filling blocks are connected as one unit. The upper serial plate and the upper filling block are relatively slidably arranged, and the lower serial plate and the lower filling block are relatively slidably arranged.

5. The electrothermal bending forming device for titanium alloy Y-shaped profiles according to claim 1, characterized in that, Insulation spraying is applied between the upper series plate and the upper filler block, and between the lower series plate and the lower filler block.

6. The electrothermal bending forming device for titanium alloy Y-shaped profiles according to claim 1, characterized in that, The surfaces of the upper and lower filler blocks are treated with insulating spray coating.

7. A method for forming a titanium alloy Y-profile using the electrothermal stretch bending forming apparatus according to any one of claims 1-6, the method comprising the following steps: In the Y-shaped electrothermal bending forming device, the sliding friction gap and lubrication conditions between the upper and lower filler blocks and the upper and lower clamping plates are set to accommodate thermal expansion and reduce friction. The dimensions of the upper and lower filler blocks are designed according to the required bending curvature characteristics of the Y-shaped profile, and multiple upper and lower filler blocks are connected into one piece by upper and lower connecting plates to form a corresponding support surface. Install the Y-shaped profile between the upper and lower clamping plates and secure it with conductive clamps; When heated by electricity, electrical energy is transferred to the upper and lower series plates through the conductive structure of the fixed block, causing the upper and lower series plates to act as heating elements and generate heat. The heat is then conducted to heat multiple upper and lower filler blocks. At the same time, the Y-shaped profile is directly heated by electricity to ensure its overall temperature uniformity; The Y-profile is pre-stretched to the yield state under heating conditions; Maintain the axial pre-tension state and perform stretch bending forming operation on the Y profile until the desired profile shape is achieved; After the stretch bending is completed, the Y-profile is subjected to additional stretch deformation and held at a certain temperature for a certain period of time to perform stress relaxation; After forming, the profile is unloaded, and a 3D scanner is used to inspect and evaluate the accuracy of the Y-profile electrothermal bending forming.

8. The method according to claim 7, characterized in that, During the bending process, a non-contact infrared thermometer is used to monitor the temperature of the upper and lower series plates and the Y-shaped profile.

9. The method according to claim 7, characterized in that, The upper and lower series plates are heated, and the temperature is controlled within the range of 500-700℃.

10. The method according to claim 7, characterized in that, The Y-shaped profile is heated by electricity, and the temperature is controlled within the range of 700-800℃.

Images