Electrically-assisted multi-pass forming method for non-equal-wall-thickness deep-cavity titanium alloy component

Abstract

The invention relates to an electric-assisted multi-pass forming method for a non-equal-wall-thickness deep-cavity titanium alloy component, which comprises the following steps of: firstly, machining a large-angle non-equal-wall-thickness prefabricated part in manners such as machining, putting the large-angle non-equal-wall-thickness prefabricated part on a core mold in a forming process, and applying pulse current to two ends of the prefabricated part to realize rapid heating of a part to be formed; and by means of a press machine with a side pressing function, the large-included-angle prefabricated part is subjected to multi-pass sufficient deformation in a power-on state through horizontal movement of the left mold and the right mold, and finally the target non-equal-wall-thickness deep-cavity titanium alloy component is obtained. Compared with the prior art, the method has the advantages that the to-be-formed part is directly and rapidly heated by adopting the low-voltage large-current pulse direct-current power supply, the whole set of die does not need to be heated, meanwhile, expensive large isothermal side pressure forming equipment is avoided, and the method has the advantages that the machining efficiency is greatly improved, the equipment cost is reduced, and the large titanium alloy deep-cavity component can be formed.

Description

Technical Field

[0001] The invention relates to the field of mechanical engineering, and in particular to an electrically assisted multi-pass forming method for a deep-cavity titanium alloy component with unequal wall thickness. Background Art

[0002] Carbon fiber composite fan blades have become the mainstream choice for commercial aircraft engines due to their light weight and strong anti-flutter performance. However, the leading edge of composite blades is still inferior to metal blades in terms of impact resistance and pressure resistance. Therefore, by coating the leading edge of composite blades with titanium alloy components, the overall performance of the composite blades can be significantly improved. However, the angle of the composite blade changes significantly from the root to the tip, and there are obvious differences between carbon fiber materials and titanium alloy materials. In order to ensure the overall performance of the blade, the titanium alloy coating has unique characteristics of non-uniform wall thickness, deep cavity, and large angle. The processing and manufacturing of such complex parts has always been a problem.

[0003] Patent CN201910666362.7 discloses a composite forming method for a large-angle thin-walled narrow deep cavity feature component, which uses a shape correction mold to heat the two side wing thin walls of the pre-processed part inward and close them together, thereby realizing the processing of the final component. However, this method requires heating and heat preservation of the entire mold, which has low production efficiency, and the mechanical properties of the parts are easily deteriorated under long-term heating and heat preservation conditions.

[0004] Patent CN201811561155.7 discloses a titanium alloy sheet electric-assisted segmented progressive forming device and method, which includes a die, a punch and a pulse power supply. The punch is gradually pressed down and in contact with the sheet, so that the pulse current forms a loop through the punch, the sheet and the die, and the sheet is gradually heated and formed. However, the vertical movement path of this punch is suitable for forming equal-thickness sheets, and it is difficult to form components with non-equal wall thickness.

[0005] Therefore, the current forming of non-uniform wall thickness deep cavity components has problems such as low production efficiency, severe oxidation, large springback, and high production cost. Through clever design, with the help of the thermal effect of electric current and the distribution characteristics of electric current in non-uniform wall thickness structures, not only can the production efficiency be greatly improved and the production cost be reduced, but also the forming performance of materials in small wall thickness areas can be effectively improved, the springback after forming can be reduced, and the efficient and high-precision forming of complex deep cavity titanium alloy components can be achieved. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide an electrically assisted multi-pass forming method for non-uniform wall thickness deep cavity titanium alloy components. The large angle non-uniform wall thickness preform is gradually transformed into the target deep cavity configuration through multi-pass electrically assisted horizontal side pressure forming.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] The present invention provides an electrically assisted multi-pass forming method for a deep-cavity titanium alloy component with unequal wall thickness, comprising the following steps:

[0009] S1. According to the structural characteristics of the target small-angle deep-cavity titanium alloy component, design and use machining and other methods to process non-uniform wall thickness and large-angle preforms and each pass of electric-assisted forming molds. Each pass of the electric-assisted forming mold includes a left mold, a right mold and a core mold;

[0010] S2, when working, the first pass electric-assisted forming die is installed on a press with a side pressure function, the workpiece to be formed is placed on the core die, and the two ends of the wire of the low-voltage and high-current pulse DC power supply are connected to the two ends of the workpiece to be formed. In the first pass, the workpiece to be formed is a prefabricated part;

[0011] S3, the pulse power supply is a low-voltage and high-current pulse DC power supply. Adjust the current parameters on the low-voltage and high-current pulse DC power supply, turn on the pulse power switch, and heat the formed part;

[0012] S4, after the large-angle preform reaches the forming temperature, the press is started, and the slide of the press drives the left and right molds to realize lateral pressure on the preform, and the pressure is maintained for a suitable time to fully deform the preform, so as to obtain a transitional formed part with a smaller angle (the smaller angle means that the angle of the transitional formed part is smaller than that of the preform before deformation);

[0013] S5. After the first forming process is completed, turn off the power supply, cut off the power supply to the transition forming part, and control the return stroke of the press;

[0014] S6. Repeat the above steps S2 to S5. The parts to be formed in each pass after the first pass are transitional formed parts obtained in the previous pass. Through the designed multi-pass electric-assisted forming, the target small-angle deep-cavity titanium alloy component can be obtained through the final pass.

[0015] Furthermore, when two-pass forming is performed, the method comprises the following steps:

[0016] S1: According to the structural characteristics of the target deep-cavity titanium alloy component, the first preform with non-uniform wall thickness and large angle and the first-pass electric-assisted forming mold, as well as the subsequent pass (second pass) electric-assisted forming mold are processed by machining and other methods. The electric-assisted forming mold includes a left mold, a right mold and a core mold. The inner surface shapes of the left and right molds of the first-pass electric-assisted forming mold are consistent with the shape of the first-pass target formed part. The core mold of the first-pass electric-assisted forming mold is used to support the first preform and ensure the inner cavity accuracy of the first-pass electric-assisted forming component. The same applies to the subsequent electric-assisted forming molds;

[0017] S2: Install the first-pass electric-assisted forming die on a press with a side-pressing function, place the first preform on the first-pass core die, and connect the two ends of the wire of the low-voltage, high-current pulsed DC power supply to the two ends of the first preform along the length direction through a clamp or other means. Install a temperature measuring device next to the press, align the temperature measuring device with the forming area of ​​the first preform, set the relevant temperature measuring parameters of the temperature measuring device according to the temperature measuring conditions, and calibrate the temperature measuring accuracy;

[0018] S3: adjusting the current parameters on the pulse power supply, turning on the pulse power switch, and heating the first preform;

[0019] S4: After the first preform reaches the forming temperature, the press parameters are adjusted and the press is started. The press slide drives the left pressing die (left die) and the right pressing die (right die) to press the first preform sideways. The pressure is maintained for a suitable time to fully deform the first preform, so as to obtain a transitional formed part with a smaller angle.

[0020] S5: After the first forming process is completed, the power supply is turned off to cut off the power supply to the formed part and control the return stroke of the press;

[0021] S6: Replace the second pass electric-assisted forming die. The second pass electric-assisted forming die still includes a left die, a right die and a core die. The inner surface shapes of the left and right dies are consistent with the shape of the target formed part. The core die is used to support the transition formed part obtained in S4 and ensure the inner cavity accuracy of the second pass electric-assisted forming component; repeat S2 to S5 to achieve the second pass electric-assisted forming and obtain the final target small-angle deep-cavity titanium alloy component.

[0022] Furthermore, the preform is horizontally pressed and formed by the left and right molds, and the core mold plays a role in supporting and ensuring the dimensional accuracy of the inner cavity of the transitional molded part.

[0023] Furthermore, the left mold, the right mold and the core mold are all made of heat-resistant stainless steel or high-temperature alloy.

[0024] Furthermore, the surface of each electrically assisted forming mold (left mold, right mold and core mold) needs to be insulated, and the specific treatment method can be spraying insulating coating.

[0025] Furthermore, the temperature change of the forming area during the electric-assisted forming process is collected and transmitted to the computer, so that the movement rate and termination condition of the press can be controlled by the computer.

[0026] Furthermore, the temperature change of the forming area during the electric-assisted forming process is collected by a temperature measuring device; the temperature measuring device is a non-contact infrared temperature measuring device.

[0027] Furthermore, the forming area is an area where the electrically assisted forming die is installed to install the part to be formed.

[0028] Furthermore, the positive electrode and the negative electrode of the low-voltage high-current pulse DC power supply are directly connected to the two ends of the to-be-formed part along the length direction.

[0029] Furthermore, in each pass of the electrically-assisted forming mold, the inner surface shape of the left mold and the right mold and the outer surface shape of the core mold are consistent with the shape of the target formed part of the corresponding pass, wherein the inner surface shape of the left mold and the right mold are consistent with the outer surface shape of the target formed part of the corresponding pass, and the outer surface shape of the core mold is consistent with the inner surface shape of the target formed part of the corresponding pass.

[0030] Furthermore, the number of electric-assisted forming passes should be selected according to the specific material performance characteristics and the characteristics of the target component.

[0031] Furthermore, the small-angle deep-cavity titanium alloy component obtained by the electric-assisted multi-pass forming method of the non-uniform wall thickness deep-cavity titanium alloy component is used to cover the leading edge of the carbon fiber composite fan blade to improve the overall performance of the carbon fiber composite fan blade.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] (1) The multi-pass blank is directly heated rapidly by a low-voltage, high-current pulsed DC power supply. Under the premise of ensuring the forming performance of the titanium alloy, the deterioration of the performance of the titanium alloy components and the influence of surface oxidation during the heating process are greatly reduced. The heating efficiency is high and the springback of the deep-cavity titanium alloy components after forming can be reduced.

[0034] (2) Based on the non-uniform distribution characteristics of current in components with non-uniform wall thickness, the current density is high in the parts with relatively thin wall thickness in the component, which in turn makes the local temperature higher and the material in the parts with relatively thin wall thickness softens significantly, thereby improving the forming performance of the material in this area, preventing the parts with relatively thin wall thickness from rupture and failure due to excessive local stress during the forming process, and reducing the rebound in this area.

[0035] (3) Considering the characteristics of the deep cavity structure of titanium alloy with non-uniform wall thickness, it is determined that the side pressure forming is realized by a press. The heating of the non-uniform wall thickness blank is realized by an electric-assisted forming device, which avoids the use of expensive large-scale isothermal side pressure forming equipment and greatly reduces the manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a structural diagram of a non-uniform wall thickness deep cavity titanium alloy component, a first preform and a transition formed component according to an embodiment of the present invention.

[0037] Figure 2 This is a schematic diagram of the electric-assisted forming device in this embodiment (taking the first forming pass as an example).

[0038] Figure numerals: 1. Non-uniform wall thickness deep cavity titanium alloy component, 2. First preform, 3. Transition formed part, 4. First left mold, 5. First right mold, 6. First core mold, 7. Low voltage and high current pulse DC power supply. DETAILED DESCRIPTION

[0039] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0040] Features such as component models, material names, connection structures, control methods, etc. that are not explicitly described in the present invention are deemed to be common technical features disclosed in the prior art.

[0041] The present invention relates to an electrically assisted multi-pass forming method for a non-uniform wall thickness deep cavity titanium alloy component. First, a large-angle non-uniform wall thickness preform is processed by machining or the like. During the forming process, the large-angle non-uniform wall thickness preform is placed on a core mold, and a pulse current is applied to both ends of the preform to achieve rapid heating of the part to be formed. With the aid of a press with a side pressure function, the large-angle preform is fully deformed in multiple passes under power-on state through horizontal movement of the left and right molds, and finally the target non-uniform wall thickness deep cavity titanium alloy component is obtained. Compared with the prior art, the present invention uses a low-voltage, high-current pulsed DC power supply to directly heat the part to be formed quickly, without heating the entire set of molds, and avoids the use of expensive large-scale isothermal side pressure forming equipment. It has the advantages of greatly improving processing efficiency, reducing equipment costs, and being able to form large titanium alloy deep cavity components.

[0042] Usually, the forming passes of deep cavity titanium alloy are preliminarily divided according to experience, the preform structure of each pass is designed, and the multi-pass forming process of deep cavity titanium alloy is simulated with the help of finite element numerical simulation. The forming feasibility of the designed number of passes and preform structure is judged according to the simulation results.

[0043] Example

[0044] This embodiment provides a method for electrically assisted multi-pass forming of a titanium alloy component with a non-uniform wall thickness and a deep cavity. Figure 1 As shown, after the first electric-assisted forming, the first preform 2 with a large angle has its angle reduced to become a transitional formed part 3. After the second electric-assisted forming, the transitional formed part 3 has its angle further reduced to obtain the target non-uniform wall thickness deep cavity titanium alloy component 1. Figure 2As shown, it specifically includes a first left mold 4, a first right mold 5, a first core mold 6 and a low-voltage high-current pulse DC power supply 7. The first left mold 4 and the first right mold 5 are respectively arranged on both sides of the first core mold 6, and the two ends of the wire of the low-voltage high-current pulse DC power supply 7 are connected to the two ends of the preform to be formed. Among them, the first left mold 4 and the first right mold 5 are installed on a press with a side pressing function, thereby realizing the movement of the two molds in the horizontal direction.

[0045] through Figure 2 The electric-assisted forming process of the titanium alloy component implemented by the device shown is achieved by the following steps:

[0046] S1: According to the structural characteristics of the target deep-cavity titanium alloy component, the first preform 2 with non-uniform wall thickness and large angle, the first pass electric-assisted forming mold, and the second pass electric-assisted forming mold are processed by machining and other methods. The first pass electric-assisted forming mold includes a first left mold 4, a first right mold 5, and a first core mold 6. The inner surface shapes of the first left mold 4 and the first right mold 5 are consistent with the shape of the first pass target formed part. The first core mold 6 is used to support the first preform 2 and ensure the inner cavity accuracy of the first pass electric-assisted forming component;

[0047] S2: Install the first pass electric-assisted forming mold on a press with a side pressure function, place the first preform 2 on the first core mold 6, and design protruding structures at both ends of the first core mold 6 to achieve positioning between the first preform 2 and the first core mold 6. The outer surface shape of the first core mold 6 is consistent with the inner cavity shape of the target formed part (transition formed part 3) of this pass. Connect the two ends of the wire of the low-voltage and high-current pulsed DC power supply to the two ends of the first preform 2 along the length direction through a clamp or other means, such as Figure 2 As shown. A tripod is used to fix an infrared thermal imager beside the press (at a distance of 0.5m), and the axis of the infrared thermal imager lens is aligned with the forming area of ​​the first preform 2. The relevant temperature measurement parameters of the temperature measurement device are set according to the temperature measurement conditions and the temperature measurement accuracy is calibrated;

[0048] S3: After adjusting the current parameters on the low-voltage and high-current pulse DC power supply 7, turn on the power switch to heat the first preform 2;

[0049] S4: After the first preform 2 reaches the forming temperature, the press parameters are adjusted and the press is started. The slide of the press drives the first left mold 4 and the first right mold 5 to horizontally press the first preform 2. The pressure is maintained for a suitable time to fully deform the first preform 2, so as to obtain a transitional formed part 3 with a smaller angle.

[0050] S5: After the first forming process is completed, the power supply is turned off, the transition forming part 3 is powered off, and the press is controlled to return;

[0051] S6: Replace the second pass electric-assisted forming mold. The second pass electric-assisted forming mold still includes a left mold, a right mold and a core mold, which are respectively a second left mold, a second right mold and a second core mold. The inner surface shapes of the second left mold and the second right mold are consistent with the shape of the target formed part (in this embodiment, a non-uniform wall thickness deep cavity titanium alloy component). The second core mold is used to support the transition formed part 3 obtained in S4 and ensure the inner cavity accuracy of the second pass electric-assisted forming component;

[0052] S6: Repeat S2 to S5 to implement the second electric-assisted forming process to obtain the final small-angle deep-cavity titanium alloy component, which is the target non-uniform wall thickness deep-cavity titanium alloy component 1.

[0053] The obtained non-uniform wall thickness deep cavity titanium alloy component 1 has the characteristics of non-uniform wall thickness, deep cavity, and small angle (generally less than 5 degrees). The preferred specific embodiments of the present invention are described in detail above. It should be understood that ordinary technicians in this field can make many modifications and changes based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by technicians in this technical field through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims. The above description of the embodiments is to facilitate ordinary technicians in this technical field to understand and use the invention. It is obvious that those familiar with the technology in this field can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by technicians in this field based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. An electrically assisted multi-pass forming method for deep-cavity titanium alloy components with non-uniform wall thickness, It is characterized in that The following steps are involved: S1. According to the structural characteristics of the target small-angle deep-cavity titanium alloy component, design and process the preforms with non-uniform wall thickness and large angle and the electric-assisted forming dies for each pass. The electric-assisted forming dies for each pass include a left die, a right die and a core die; S2, when working, the first pass electric-assisted forming die is installed on a press with a side pressure function, the workpiece to be formed is placed on the core die, and the two ends of the wire of the low-voltage and high-current pulse DC power supply are connected to the two ends of the workpiece to be formed. In the first pass, the workpiece to be formed is a prefabricated part; S3, the pulse power supply is a low-voltage and high-current pulse DC power supply. Adjust the current parameters on the low-voltage and high-current pulse DC power supply, turn on the pulse power switch, and heat the formed part; S4, after the preform reaches the forming temperature, the press is started, and the slide of the press drives the left and right molds to realize lateral pressure on the preform, and the pressure is maintained for a suitable time to fully deform the preform, so as to obtain a transitional formed part with a smaller angle; S5. After the first forming process is completed, turn off the power supply, cut off the power supply to the transition forming part, and control the return stroke of the press; S6. Repeat the above steps S2 to S5. The part to be formed in each pass after the first pass is the transitional formed part obtained in the previous pass. Through multiple passes of electric-assisted forming, the target small-angle deep-cavity titanium alloy component is obtained, that is, the non-uniform wall thickness deep-cavity titanium alloy component.

2. The electrically assisted multi-pass forming method for a deep-cavity titanium alloy component with unequal wall thickness according to claim 1, It is characterized in that The preform is horizontally pressed and formed by the left and right molds, and the core mold plays a role in supporting and ensuring the dimensional accuracy of the inner cavity of the transitional molded part.

3. The electrically assisted multi-pass forming method for a deep-cavity titanium alloy component with unequal wall thickness according to claim 2, It is characterized in that The left mold, right mold and core mold are all made of heat-resistant stainless steel or high-temperature alloy.

4. The electrically assisted multi-pass forming method for a titanium alloy component with a non-uniform wall thickness and a deep cavity according to claim 2, It is characterized in that The surfaces of the left mold, the right mold and the core mold are all subjected to insulation treatment.

5. The electrically assisted multi-pass forming method for a deep-cavity titanium alloy component with unequal wall thickness according to claim 1, It is characterized in that The temperature changes in the forming area during the electric-assisted forming process are collected and transmitted to the computer, so that the movement rate and termination conditions of the press can be controlled by the computer.

6. The electrically assisted multi-pass forming method for a deep-cavity titanium alloy component with unequal wall thickness according to claim 5, It is characterized in that The temperature change of the forming area during the electric-assisted forming process is collected by a temperature measuring device; The temperature measuring device is a non-contact infrared temperature measuring device.

7. The electrically assisted multi-pass forming method for a titanium alloy component with a non-uniform wall thickness and a deep cavity according to claim 6, It is characterized in that The forming area is the area where the electric-assisted forming die is installed to install the part to be formed.

8. The electrically assisted multi-pass forming method for a deep-cavity titanium alloy component with unequal wall thickness according to claim 1, It is characterized in that The positive and negative electrodes of the low-voltage, high-current pulse DC power supply are directly connected to the two ends of the part to be formed along the length direction.

9. The electrically assisted multi-pass forming method for a titanium alloy component with a non-uniform wall thickness and a deep cavity according to claim 1, It is characterized in that Machining is used to process preforms with non-uniform wall thickness and large angles and electric-assisted forming dies for each pass.

10. The electrically assisted multi-pass forming method for a titanium alloy component with a non-uniform wall thickness and a deep cavity according to claim 1, It is characterized in that In each pass of the electrically assisted forming die, the shapes of the inner surfaces of the left die and the right die and the outer surface of the core die are consistent with the shape of the target formed part of the corresponding pass.

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