Spinning-additive composite forming process method for copper-nickel bimetal complex curved busbar component

Abstract

The invention discloses a spinning-additive composite forming process method for a copper-nickel bimetal complex curved busbar component, and particularly relates to the technical field of material forming. The copper-nickel bimetallic component in a complex shape can be machined through spinning-additive composite machining, and the method is suitable for manufacturing a complex curved generatrix metal component. By optimizing the technological parameters of spinning and electric arc material increase, the structure property of the material can be effectively improved, and the forming precision can be improved. The method comprises the following steps that a copper alloy cylindrical part blank is preheated within the temperature range of 400 DEG C, and it is ensured that the material has proper plasticity; a spinning die suitable for a complex curved bus is designed, multi-pass spinning is carried out, and the needed curved bus copper alloy component is machined step by step; then nickel-based alloy is added to the surface of the component, and secondary spinning is carried out to obtain a bimetallic component with high bonding strength; the material is subjected to uniform plastic deformation by adjusting the pressure and the feeding rate of the spinning roller; and finally, post-treatment is conducted, residual stress is eliminated, and the geometric accuracy of the formed part is ensured.

Description

Technical Field

[0002] This invention relates to the field of plastic forming technology for composite metal materials, and in particular to a spin-additive composite forming process for complex curved busbar components of copper-nickel bimetallic materials. Background Technology

[0004] With the increasing demand for high-performance materials in modern manufacturing, traditional metal forming methods (such as casting and forging) face numerous challenges in manufacturing certain materials and complex-shaped components. This is particularly true for copper-nickel bimetallic components with complex curved generatrices, which are difficult to form and require high machining precision. Existing spinning processes are mostly applied to components with simple geometries, and effective process and mold designs are still lacking for machining copper alloy components with complex curved generatrices. Due to the complex structure of curved generatrices, spinning presents certain technical difficulties and challenges, and ordinary molds are unlikely to meet the machining requirements of complex parts. Therefore, mold adaptability design and development are necessary.

[0005] However, relying solely on traditional spinning technology still struggles to address the processing challenges of complex-shaped components, especially in the manufacture of bimetallic components. How to combine different materials using technical means while ensuring good bonding and mechanical properties remains a current technological hurdle. To address this, a spinning-additive composite forming process is proposed. This process uses a spinning-additive composite machining method to form a nickel-based alloy protective layer on the surface of a spun copper alloy part through arc additive manufacturing. This process combines traditional hot spinning and arc additive manufacturing techniques to manufacture copper-nickel bimetallic components. Through arc additive manufacturing, the nickel-based alloy is additively applied to the surface of the copper alloy component to form a bimetallic component. This composite forming process not only effectively solves the technical bottleneck of traditional spinning processes in processing complex curved generatrice shapes but also enhances the overall performance of the component through the high-temperature stability and corrosion resistance of the nickel-based alloy. The arc additive manufacturing process allows for localized reinforcement of materials in areas requiring strengthening, optimizing the mechanical properties of the component and enhancing its application value in high-temperature and corrosive environments. In actual industrial production, such composite processing methods have the advantages of easy-to-meet plastic forming conditions and simple forming processes, which can improve industrial production efficiency, produce products with better performance, and reduce manufacturing costs. Summary of the Invention

[0007] To address the technical problems in fabricating components with complex curved busbar structures of double-layer metals in existing technologies, this invention provides a spin-additive composite forming process for copper-nickel bimetallic complex curved busbar components. By designing the copper alloy spin-forming blank, mold, and processing technology, copper alloy components with the required precision and performance can be fabricated simply by replacing the mold on existing spin-forming machine tools. Furthermore, an arc additive manufacturing method is incorporated into the spin-forming process, and an automated processing program is used to perform a secondary spin-forming of the composite bimetallic component. This ensures reliable composite bonding between the two different materials, thereby improving production efficiency, reducing production costs, and enhancing product precision.

[0008] The technical solution adopted to solve the above-mentioned technical problems is as follows:

[0009] A spin forming-additive composite forming process for complex curved busbar components in copper-nickel bimetallic materials includes the following steps.

[0010] S1 Based on the geometry and wall thickness distribution of the target component, design and manufacture a segmented assembly core mold and a butterfly-shaped rotary wheel mold with curved generatrix structures at both ends and a transition structure in the middle;

[0011] S2. The cylindrical copper alloy blank is fitted onto the segmented mold and positioned and fixed by the axial tail or flange. The diameter of the blank is 1 to 3 mm larger than the maximum diameter of the mold.

[0012] S3 uses an electromagnetic induction heating device to preheat the blank, raising the overall temperature of the blank to 380-430℃ and holding it at that temperature for 60-300 seconds. At the same time, infrared thermometers or thermocouples are used to monitor the temperature every 30 seconds at the front, middle and rear positions.

[0013] S4 Under the temperature conditions, spinning is carried out in stages according to a preset program, including two stages: ordinary spinning and strong spinning. The feed rates of the spinning wheel corresponding to different stages are 0.01~0.05 mm / r and 0.008~0.03 mm / r, respectively, and the spindle speed is 120 r / min, so that the blank is gradually thinned from the initial wall thickness t0 to the intermediate thickness t1 and finally close to the target thickness t2.

[0014] S5 After the initial spinning is completed and cooled to about 80-150°C, the arc additive manufacturing device is started to add material to the outer surface of the spun part circle by circle. The additive is deposited circle by circle using nickel-based welding wire, with a wire feed speed of 2-8 m / min, an arc current of 80-220 A, an arc length controlled at 2-6 mm, and the additive layer accumulates to a predetermined thickness h (1-4 mm).

[0015] S6 After the additive manufacturing is completed and initially cooled, the additive head is removed, and a pre-programmed secondary spinning procedure is used to perform hot spin shaping on the additive layer and the substrate. The spin roller pressure is increased by 10% to 40% compared to the first stage during the secondary spinning, and the process is carried out at a temperature of 500°C to achieve plastic interlocking and densification of the interface.

[0016] S7. The component after secondary spinning is subjected to stress-relieving heat treatment, which is carried out in a protective atmosphere (such as argon or nitrogen) at 500-700℃ for 30-120 min and then slowly cooled to room temperature.

[0017] S8 demolding and non-destructive testing and necessary surface finishing of the component surface and interface are performed to obtain the final morphology and structurally stable copper-nickel bimetallic complex curved busbar component.

[0018] Furthermore, in step S1, the mold is designed as a combination of two large and two small segments, with the transition part in the middle using an appropriate arc design, which serves both as a transition and a connection.

[0019] Furthermore, in step S1, the combination of the segmented molds refers to the connection between the left and right ends via the middle connecting part, while the segmentation refers to the fact that the mold on the side fixed to the machine tool is composed of segmented molds. This design is to ensure the safety and reliability of the molds.

[0020] Furthermore, in step S2, the diameter of the cylindrical blank should be 2mm larger than the maximum diameter of the mold and smaller than the diameter of the electromagnetic induction heating coil to ensure safe electromagnetic induction heating.

[0021] Furthermore, during the processing in step S4, the processing status should be observed at all times and the feed rate should be adjusted accordingly to ensure the smooth progress of the processing.

[0022] Furthermore, in step S4, attention should be paid to waiting for the initial spinning process to be completely completed, and the spinning wheel should be returned to a safe position that will not affect subsequent processing before performing arc additive manufacturing;

[0023] Furthermore, during the arc additive manufacturing process in step S5, the spindle of the spinning machine should be kept rotating, and the rotation speed should be adapted to the additive speed of the arc additive manufacturing.

[0024] Furthermore, in step S5, additive manufacturing can be performed by fixing the arc additive manufacturing head and rotating only the spindle of the spinning machine. However, attention should be paid to the distance between the arc additive manufacturing head and the component to ensure better additive manufacturing results.

[0025] Furthermore, in step S6, the pre-programmed secondary spinning process should only be run after the arc additive manufacturing process is completed and the processing head has come to a stable position, in order to avoid interference that could damage the equipment.

[0026] Furthermore, the secondary spinning process program written in step S6 should be a strong spinning and shaping program to ensure that the component can be processed to the required thickness and that there is a strong bonding strength between different metals.

[0027] Furthermore, in step S8, after the workpiece has completely cooled to room temperature, the mold and the workpiece are removed from the machine tool as a whole. Then, the split mold is disassembled, and the workpiece is taken out and completely demolded.

[0028] Furthermore, prior to step S1, based on parameters such as the wall thickness, diameter, and trimming allowance of the curved busbar component, and in accordance with the principle of constant volume and the shear-spinning sine law, a cylindrical blank is prefabricated.

[0029] This invention is rationally designed and can be widely applied in the field of plastic forming technology of metal materials, and has the following beneficial effects:

[0030] 1. This invention can realize the hot spinning forming of complex curved busbar components of copper alloy. The heating process is carried out by electromagnetic induction heating, which can greatly improve the heating efficiency.

[0031] 2. By combining and segmenting the mold, this invention can not only process complex curved generatrix structures, but also demold in a relatively simple way, which can effectively improve production efficiency.

[0032] 3. The method of this invention simplifies the complicated processing steps of traditional processing methods, and the integral forming method can improve the utilization rate of materials and reduce material waste while ensuring processing accuracy.

[0033] 4. This invention combines spinning and arc additive manufacturing technology, which can produce copper-nickel bimetallic components with good performance more efficiently. It can combine the high thermal conductivity of copper alloys with the high strength and thermal stability of nickel-based alloys, so that the components have more comprehensive service performance and broader application prospects.

[0034] 5. The present invention performs appropriate heat treatment on the processed workpiece to make the bond between the two metal layers tighter. In addition, it can effectively eliminate the residual stress after secondary spinning, making the overall shape and structure more stable. Attached Figure Description

[0036] Figure 1 This is a flowchart of the method steps of the present invention;

[0037] Figure 2 This is a schematic diagram of a complex curved busbar component made of copper alloy prepared according to the present invention;

[0038] Figure 3 This is a schematic diagram of the multi-pass conventional spinning forming process used in this invention; Figure 4 This is a schematic diagram showing the radial relationship between the electromagnetic induction heating device used in this invention and the workpiece;

[0039] In the diagram: 1. Complex curved mold; 2. Cylinder with uniform wall thickness; 3. Gear; 4. Collar; 5. Flange; 6. Workpiece to be processed; 7. Electromagnetic induction coil; Detailed Implementation

[0041] The following is combined with Figures 1 to 3 The present invention will be further described below.

[0042] A spin-additive composite forming process for complex curved busbar components in copper-nickel bimetallic alloys can be used to manufacture such components. This process mainly consists of three steps: hot spin forming of the copper alloy, arc additive manufacturing of the nickel-based alloy on the surface of the spun part, and secondary spin forming of the bimetallic component.

[0043] The specific process is as follows:

[0044] Step 1: Prepare the spinning blank:

[0045] A copper alloy cylindrical part is selected, and a spinning blank is prepared using conventional machining methods. The blank has an inner diameter of 180 mm, a wall thickness of 10 mm, a length of ≥100 mm, and is made of chromium-zirconium copper alloy C18150.

[0046] Step 2: Install and fix the segmented mold:

[0047] The mold is a complex curved generatrix mold 1, which features segmented and partitioned sections. The part connected to the machine tool adopts a segmented mold design, and the segments of the segmented mold are axially fixed by a collar 4. The collar is then connected to the flange 5 by a pin, and the flange is fixed to the machine tool. The front end of the mold is designed as a complete curved generatrix structure, with an interlocking mechanism in the middle for connection and fixation. The overall weight of the mold can be reduced and its reliability improved by appropriately hollowing out the mold for lightweight design.

[0048] Step 3: Loading and installing the blank:

[0049] The pre-made copper alloy cylindrical blank is placed on the mold, and then the tail end of the mold is fixed by the tail of the machine tool to ensure the reliability of the fixation and prevent slippage and instability during the spinning process.

[0050] Step 4: Preheat the billet:

[0051] The copper alloy cylindrical part is preheated using an electromagnetic induction coil. The heating temperature is adjusted by regulating parameters such as current and voltage. During the heating process, an infrared thermometer can be used to measure the temperature every 30 seconds. When the temperature rises to 400℃, heating can be stopped, and then the electromagnetic induction coil can be slowly moved back to a safe position.

[0052] Step 5: Spin forming of complex curved copper alloy components:

[0053] Based on the provided cylindrical blank with a wall thickness of 10mm, ordinary spinning is first performed to initially shape the component, and then strong spinning is performed to reduce the wall thickness of the component to the target thickness of 6mm and apply a film to prepare for subsequent electric arc additive manufacturing. After the program is completed, the spinning wheel is moved back to a safe position.

[0054] Step 6: Using arc additive manufacturing to fabricate the nickel-based alloy surface of the component:

[0055] The arc additive manufacturing device is modified to be located near the spinning machine, allowing the robotic arm of the arc additive manufacturing device to directly process the surface of the spun part. Note that during the processing, the machine tool spindle can rotate at a constant speed in the circumferential direction, while the arc additive manufacturing device remains stationary. After one revolution is completed, it moves along the axis to begin the next revolution, and so on, until a layer of nickel-based alloy is added to the entire surface of the workpiece. At this point, it should be ensured that the rotational linear speed of the component is less than or equal to the wire feeding speed of the arc additive manufacturing device to ensure uniform addition of nickel-based alloy to the surface of the copper alloy component. The thickness of the bimetallic component after arc additive manufacturing should be 8mm.

[0056] Step 7: After surface additive manufacturing is completed, perform secondary spinning:

[0057] After the arc additive manufacturing is completed, the robotic arm of the arc additive manufacturing is moved to a safe position, and the pre-numbered and verified spinning program is started to perform secondary spinning processing on the nickel-copper bimetallic component that has undergone arc additive manufacturing. The hot spinning method is used to thin the component to 6mm. When the program finishes running, the spinning wheel is placed in a safe position and the machine tool is turned off.

[0058] Step 8: Disassemble the mold:

[0059] After the processing steps are completed, appropriate measures should be taken to remove the mold from the machine tool. First, use an overhead crane to drive the hanging basket to fix the mold and components together in a special hanging basket. Then, remove the fixing bolts on the flange connected to the machine tool to separate the mold from the machine tool. Transfer the removed mold and components to a safe area.

[0060] Step 9: Demolding of components:

[0061] In a safe area, demold the component by first separating the flange from the collar, then disassembling one side of the segmented mold. Use a wooden hammer to gently tap the smallest segment of the mold until it loosens, then gradually remove the other parts. Once the segmented mold side is demolded, the entire component can be removed directly from the other side, thus completing the demolding of the component.

[0062] The above technical solutions illustrate the technical concept of the present invention, but should not be construed as limiting the scope of protection of the present invention. Any modifications or alterations made to the above technical solutions based on the technical essence of the present invention, including the replacement of the substrate material and the additive material, the selection of the heating method and the selection of the additive method, including but not limited to laser-directed energy deposition, arc additive manufacturing and plasma beam additive manufacturing, shall fall within the scope of protection of the present invention.

Claims

1. A spinning-additive hybrid forming process method of a copper-nickel bimetallic complex curved generatrix component, characterized in that, The method comprises the following steps: S1, designing and manufacturing a split combined core mold and a butterfly-shaped spinning roller mold with a curved generatrix structure at both ends and a transition structure in the middle according to the target component geometry and wall thickness distribution; S2, sleeving a cylindrical copper alloy blank on the split mold and positioning and fixing it axially with a tail top or a flange, the diameter of the blank being 1-3 mm larger than the maximum diameter of the mold; S3, using an electromagnetic induction heating device to heat and pretreat the blank, raising the overall temperature of the blank to 380-430℃ and maintaining it for 60-300 s, and monitoring the temperature at the front, middle and rear positions every 30 s using an infrared temperature measuring device or a thermocouple; S4, under the temperature conditions, implementing spinning processing in stages according to a preset program, including two stages of general spinning and strong spinning, the roller feed rates of different stages being 0.01-0.05 mm / r and 0.008-0.03 mm / r respectively, and the spindle speed being 120 r / min, so that the blank is gradually thinned from the initial wall thickness t0 to the intermediate thickness t1 and finally approaches the target thickness t2; S5, when the initial spinning is completed and cooled to about 80-150℃, starting an electric arc additive device to add materials to the outer surface of the spun part circle by circle, the additive material being a nickel-based welding wire deposited every week, the wire feeding speed being 2-8 m / min, the arc current being 80-220 A, and the arc length being controlled at 2-6 mm, and the additive layer being accumulated to a predetermined thickness h (1-4 mm); S6, after the additive is completed and preliminarily cooled, removing the additive head and using a pre-programmed secondary spinning program to perform hot strong spinning shaping on the additive layer and the substrate, the roller pressure in the secondary spinning being increased by 10%-40% compared with the first stage, and the temperature being 500℃, so as to realize interface plastic engagement and densification; S7, performing stress relief heat treatment on the component after the secondary spinning, the heat treatment being performed in a protective atmosphere (such as argon or nitrogen) at 500-700℃ for 30-120 min and then slowly cooled to room temperature; S8, demolding and performing non-destructive testing and necessary surface finishing on the surface and interface of the component to obtain a final appearance and a structure-stable copper-nickel bimetallic complex curved generatrix component.

2. The method of claim 1, wherein, The copper alloy is chromium-zirconium copper (C18150) or aluminum bronze (QAl9-2), and the nickel-based additive material is selected from one of Inconel625, Inconel718 or NiCr welding wire.

3. The method of claim 1, wherein, The middle transition section of the split combined mold in S1 is provided with a proper circular arc transition radius according to the curved generatrix profile, and a shaft ring and pin locking structure is arranged at the split part to ensure coaxiality and convenience in disassembly.

4. The method of claim 1, wherein, In S3, the radial distance between the heating coil and the outer surface of the blank is 5-30 mm, and the heating rate is controlled at 5-30℃ / s to prevent local overheating or thermal stress concentration.

5. The method of claim 1, wherein, In S3, an infrared temperature measuring instrument or a K-type thermocouple is used for temperature monitoring, and when the temperature measured at any position for two consecutive times is greater than or equal to the set temperature (for example, 400℃), the heating is stopped and the heating coil is slowly withdrawn to enter the spinning step.

6. The method of claim 1, wherein, The change of the blank wall thickness t with the radius r in the multi-stage spinning process satisfies the approximate volume conservation relationship: The thickness true strain is controlled by: , and the thinning rate is within a reasonable range.

7. The method of claim 1, wherein, The spindle torque, spinning wheel pressure and workpiece circumferential temperature are monitored in real time during the whole spinning process. According to the monitoring signals, the feed rate and spindle speed are self-adaptively adjusted by closed-loop control to avoid defects such as slipping, wrinkling, bulging or tearing.

8. The method of claim 1, wherein, In the electric arc additive process, a fixed additive head and a rotating workpiece are used, or a rotating additive head and a stationary workpiece are used as an alternative layout. The distance between the additive head and the workpiece surface is kept at 5-30 mm. The width of the molten pool and the thickness of the additive layer are matched through the coordination of wire feeding speed, current and arc energy to realize interlayer metallurgical bonding.

9. The method of claim 1, wherein, S5 additive line energy The control is in the range of 0.5-1.8 kJ / mm, taking into account the stability of the molten pool and the control of the heat affected zone on the copper base.

10. The method of claim 1, wherein, After the additive process, pulse or pressure-keeping secondary spinning is performed between the additive layer and the substrate to close the interface pores and induce micro-plastic flow, so as to promote limited-scale diffusion and recrystallization at the interface, forming a diffusion transition layer with a thickness of 3-15 μm.

11. The method of claim 1, wherein, The spinning wheel pressure used in the secondary spinning is 1.1-1.5 times the pressure of the primary spinning, and the linear speed is matched with or synchronized with the rotational linear speed during the additive process at a set ratio to reduce the interface shear.

12. The method of claim 1, wherein, The stress relief heat treatment is carried out in a protective atmosphere to prevent oxidation at the interface of nickel-based and copper-based materials. The protective atmosphere is preferably pure argon or argon gas flow of 0.5-5 L / min.

13. The method of claim 1, wherein, The demolding adopts a method of disassembling the mold in parts, and the demolding sequence is to release the thin part first and take the thick part later to avoid damage to the surface of the component due to elastic rebound of the workpiece.

14. The method of claim 1, wherein, In the process, the interface bonding quality is determined by non-destructive testing (ultrasonic or phased array).

15. The method of claim 1, wherein, The process realizes linkage control of the spinning stage, the additive stage and the secondary spinning stage through numerical control program, and can be interconnected with online temperature, torque and force sensors to form a closed-loop automatic control system.

16. The method of claim 1, wherein, The method is suitable for components with a target curved generatrix geometric accuracy requirement of ±0.1 mm, and the geometric deviation can be controlled within ±0.05 mm after processing by the process.

17. The method of claim 1, wherein, For applications under corrosive or high-temperature working conditions, the additive layer can be further treated by laser surface remelting or plasma cladding after the additive process to refine the grains and improve the surface density.

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