Titanium-aluminum composite material mobile phone middle frame processing technology

Abstract

The invention relates to the technical field of mobile phone middle frame machining, in particular to a titanium-aluminum composite material mobile phone middle frame machining process which comprises the steps that a titanium-aluminum composite strip formed by connecting two layers of titanium and aluminum composite materials is adopted as a frame of a mobile phone middle frame, and an aluminum plate is adopted as an inner side plate connected into the frame of the mobile phone middle frame; wherein the titanium layer in the titanium-aluminum composite strip is located on the outer side of the frame of the mobile phone middle frame, and the aluminum layer in the titanium-aluminum composite strip is located on the inner side of the frame of the mobile phone middle frame; the frame of the mobile phone middle frame is connected with the inner side plate of the mobile phone middle frame through friction stir welding. The comprehensive performance of the mobile phone middle frame is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of mobile phone middle frame processing, and in particular to a processing technology for a mobile phone middle frame made of titanium-aluminum composite material. Background Art

[0002] The mobile phone middle frame is located between the front screen and the back cover of the phone. It plays the role of protecting the internal motherboard of the phone, so it needs to have high strength requirements. In addition, since the outer periphery of the mobile phone middle frame is exposed, its appearance requirements and scratch and drop resistance requirements are also high. In addition, in order to improve market competitiveness, the mobile phone middle frame also needs to have high production efficiency and low manufacturing costs. Therefore, the comprehensive performance requirements of the mobile phone middle frame are relatively high.

[0003] Currently, most mobile phone midframes are made of a single material or alloy, forged or pressed into shape through a die, and then CNC machined to create the final mobile phone midframe product. However, due to the low overall performance of traditional single materials or alloys, the use of composite materials in mobile phone midframes is an important way to improve their overall performance. Summary of the Invention

[0004] To solve the above problems, the present invention proposes a titanium-aluminum composite mobile phone middle frame processing technology, aiming to improve the comprehensive performance requirements of the mobile phone middle frame. The specific technical solution is as follows:

[0005] A process for processing a mobile phone middle frame made of titanium-aluminum composite material, using a titanium-aluminum composite strip formed by connecting two layers of titanium and aluminum composite materials as the frame of the mobile phone middle frame, and using an aluminum plate as the inner plate connected to the frame of the mobile phone middle frame; wherein the titanium layer in the titanium-aluminum composite strip is located on the outside of the frame of the mobile phone middle frame, and the aluminum layer in the titanium-aluminum composite strip is located on the inside of the frame of the mobile phone middle frame; the frame of the mobile phone middle frame and the inner plate of the mobile phone middle frame are connected by friction stir welding.

[0006] Preferably, the titanium-aluminum composite strip is formed by rolling and composite connecting a titanium strip as the titanium layer and an aluminum strip as the aluminum layer.

[0007] Preferably, the frame of the mobile phone middle frame is a combined frame formed by splicing four titanium-aluminum composite strips.

[0008] Among them, two of the four titanium-aluminum composite bars are straight titanium-aluminum composite bars, and the other two of the four titanium-aluminum composite bars are bent titanium-aluminum composite bars formed by bending the titanium-aluminum composite bars. The two straight titanium-aluminum composite bars are arranged in parallel and spaced apart, and the two ends of the two bent titanium-aluminum composite bars are respectively connected to the two ends of the two straight titanium-aluminum composite bars, thereby forming the border of the middle frame of the mobile phone.

[0009] In the present invention, the frame thickness of the mobile phone middle frame is set to be equal to the thickness of the aluminum plate.

[0010] A titanium-aluminum composite mobile phone middle frame processing process includes the following steps:

[0011] (1) Grinding to remove burrs: Grinding is used to remove burrs on the two outer surfaces of the junction of the titanium and aluminum layers.

[0012] (2) Cutting to length and bending: The titanium-aluminum composite strip is cut to a set length to make four titanium-aluminum composite strips, and two of the titanium-aluminum composite strips are bent to obtain two straight titanium-aluminum composite strips and two bent titanium-aluminum composite strips;

[0013] (3) Finishing: trimming the front and rear surfaces of the bent portion of the bent titanium-aluminum composite strip to remove the increased thickness of the bent portion caused by the bending;

[0014] (4) Assembly and welding: four titanium-aluminum composite strips are assembled with the aluminum plate so that the four titanium-aluminum composite strips are spliced ​​on the outside of the aluminum plate to form a frame around the aluminum plate, forming a spliced ​​assembly of the mobile phone middle frame. Then, friction stir welding is used to weld the titanium-aluminum composite strips and the aluminum plate connected to each other in the spliced ​​assembly together to obtain an assembled welded body of the mobile phone middle frame.

[0015] (5) Machining: The upper and lower surfaces of the assembled welded body are polished and smoothed, and then CNC machining is performed to produce the finished mobile phone middle frame.

[0016] Preferably, during the trimming process in step (3), the processing equipment used is a double-sided grinder or a CNC machine tool.

[0017] Preferably, during the assembly welding in step (4), the friction stir welding starts from a joint between the straight titanium-aluminum composite strip and the bent titanium-aluminum composite strip, and after cutting, welds a circle along the periphery of the connection between the frame of the mobile phone middle frame and the inner plate of the mobile phone middle frame, and then exits from the joint or from the aluminum plate that serves as the subsequent CNC processing removal area.

[0018] In the present invention, during the assembly welding in step (4), a welding positioning tool is used, and the four titanium-aluminum composite strips and the aluminum plate are placed in the welding positioning tool for positioning and fixing before the friction stir welding is performed.

[0019] Preferably, the welding positioning tooling includes a base, a positioning groove arranged on the upper plane of the base, and the assembled assembly of the mobile phone middle frame is positioned as a whole in the positioning groove of the base; a number of automatic advance and retreat clamping devices for clamping and fixing the outer edge of the frame are also arranged around the upper plane of the base, and a vacuum adsorption device for fixing the aluminum plate by vacuum adsorption is also provided in the middle part of the bottom of the positioning groove on the base; during the assembly welding in step (4), an XYZ three-dimensional CNC friction stir welding machine is used to perform the friction stir welding.

[0020] Preferably, the automatic advance and retreat pressing device includes a pressure plate movably arranged above the base, a guide column uprightly arranged on the upper end surface of the base, a cylinder mounting hole set on the base and penetrating the up and down directions, and a cylinder fixed to the lower end of the base, the upper part of the cylinder mounting hole is provided with an expansion hole, a compression spring is provided in the expansion hole, and a waist-shaped hole and an obliquely arranged guide hole are respectively provided on the pressure plate, and the front end of the piston rod of the cylinder passes through the cylinder mounting hole, the compression spring inner hole and the waist-shaped hole in turn, and is connected to a pressure head for pressing the pressure plate, and the guide column is inclined toward the outer side of the base, and the guide hole on the pressure plate is sleeved on the guide column and slidably connected to the guide column.

[0021] The above oil cylinder can also be replaced by an air cylinder. For convenient control, the electromagnetic valves for controlling the oil cylinder or the air cylinder are connected to the control system respectively.

[0022] When the piston rod of the oil cylinder moves upward, driving the pressure head at its front end to lift upward, the pressure plate rises upward and outward along the inclined guide column under the action of the compression spring, and the workpiece (the assembled components of the mobile phone middle frame) can be loaded and unloaded without interfering with the pressure plate.

[0023] As a further improvement of the present invention, a first annular groove is provided on the bottom plane of the positioning groove of the base and directly opposite to the position of the welding seam. A friction stir welding temperature equalization compensator is built into the first annular groove for heating the back of the weld to equalize the temperature of the upper and lower positions of the weld.

[0024] Preferably, the friction stir welding temperature equalization compensator includes an annular magnet installed in and adapted to the first annular groove, a second annular groove opened on the annular magnet and opening upward, an annular copper tube arranged in the second annular groove, the annular copper tube is provided with a slit for disconnecting the annular copper tube, and a plug is provided at the mouth of the slit of the annular copper tube; a pair of electrode copper tubes are led downward from both sides of the annular copper tube near the slit, the interior of the electrode copper tube is connected to the interior of the annular copper tube, the pair of electrode copper tubes pass downward through the base and are connected to an external industrial frequency power supply, and cooling circulating water is passed through the interior of the electrode copper tube.

[0025] After the workpiece (the assembled components of the mobile phone middle frame) is positioned and clamped into the welding positioning fixture, the control system turns on the industrial frequency power supply of the friction stir welding temperature equalization compensator to achieve directional magnetic induction heating of the upper workpiece. This works in conjunction with friction stir welding, which is beneficial to improving the temperature uniformity and welding temperature stability of the upper and lower positions of the weld between the frame and the aluminum plate, thereby overcoming the disadvantage of uneven upper and lower temperatures that may exist when using friction stir welding alone, and is beneficial to further improve the stability of welding quality.

[0026] Preferably, the vacuum adsorption device includes a concave countersunk hole provided on the bottom plane of the positioning groove in the middle portion, a sealing annular groove provided on the bottom plane of the positioning groove and located between the first annular groove and the concave countersunk hole, an annular sealing ring installed in the sealing annular groove, and a vacuum adsorption hole provided on the base and communicating with the concave countersunk hole, wherein the vacuum adsorption hole is connected to a vacuum pumping device via a vacuum adsorption pipeline. The vacuum pumping device is connected to a control system.

[0027] Preferably, the electrode copper tube is an electrode copper tube with a rectangular cross-sectional shape, and the upper end surface of the electrode copper tube with a rectangular cross-sectional shape is lower than the upper end surface of the annular magnetic conductor.

[0028] In the present invention, a robot is also provided for automatically installing and positioning the assembled components of the mobile phone middle frame into the welding positioning tool before welding, and removing the assembled welded body of the mobile phone middle frame from the welding positioning tool after welding.

[0029] The beneficial effects of the present invention are:

[0030] First, the present invention discloses a titanium-aluminum composite mobile phone middle frame processing process. This process utilizes titanium-aluminum composite strips as the frame of the mobile phone middle frame, aluminum plates as the inner plate of the mobile phone middle frame, and utilizes friction stir welding for post-assembly welding of the mobile phone middle frame. This process ensures the strength requirements of the mobile phone middle frame, while titanium, as the exposed portion of the mobile phone middle frame, provides a good appearance and is scratch-resistant and drop-resistant. Furthermore, the machined portion of the mobile phone middle frame is primarily aluminum, making it easy and efficient to machine. Furthermore, friction stir welding utilizes the high-speed rotation and stirring of a stirring pin inserted into the weld seam on the friction stir welding equipment, as well as the friction between the upper shoulder of the stirring pin and the upper end of the weld seam to generate heat, softening the frame aluminum and the aluminum plates and welding them together. This process offers the advantages of high thermal efficiency, low welding temperature, minimal welding deformation, and high welding strength, thereby improving the overall performance of the mobile phone middle frame.

[0031] Second, the present invention provides a titanium-aluminum composite mobile phone middle frame processing technology. The automatic advance and retreat clamping device can automatically clamp the workpiece (the assembled components of the mobile phone middle frame) and automatically make way for the workpiece to be taken out when unloading the workpiece. This greatly facilitates the efficient installation of the workpiece into the welding positioning tooling by the robot and enables rapid retrieval, thereby further improving production efficiency.

[0032] Third, in the processing technology of the titanium-aluminum composite mobile phone middle frame of the present invention, the arrangement of the friction stir welding temperature equalization compensator on the welding positioning tool further improves the welding quality of the friction stir welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of a process for processing a titanium-aluminum composite mobile phone middle frame according to the present invention;

[0034] Figure 2 This is a schematic diagram of the structure of the titanium-aluminum composite mobile phone middle frame;

[0035] Figure 3 It is a schematic diagram of the structure of titanium aluminum composite strip;

[0036] Figure 4 It is a structural diagram of the welding positioning tooling;

[0037] Figure 5 yes Figure 4 A partial enlarged view of

[0038] Figure 6 yes Figure 5 Schematic diagram of the structure of the base (top view);

[0039] Figure 7 yes Figure 5 Schematic diagram of the structure of the annular copper tube (bottom view).

[0040] In the figure: 1. titanium-aluminum composite strip, 2. frame, 3. aluminum plate, 4. titanium layer, 5. aluminum layer, 6. straight titanium-aluminum composite strip, 7. bent titanium-aluminum composite strip, 8. butt joint, 9. welding positioning tool, 10. base, 11. positioning groove, 12. automatic advance and retreat clamping device, 13. vacuum adsorption device, 14. first annular groove, 15. friction stir welding temperature equalization compensator, 16. annular magnet, 17. second annular groove, 18. annular copper tube, 19. slit, 20. plug, 21. electrode copper tube, 22. concave countersunk hole, 23. sealing annular groove, 24. annular sealing ring, 25. vacuum adsorption hole, 26. vacuum adsorption pipeline, 27. support foot, 28. pressure plate, 29. guide column, 30. cylinder mounting hole, 31. cylinder, 32. compression spring, 33. waist-shaped hole, 34. pressure head. DETAILED DESCRIPTION

[0041] The following embodiments are further described in conjunction with the accompanying drawings and examples. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0042] like Figures 1 to 7 The figure shows an embodiment of the processing technology of a titanium-aluminum composite mobile phone middle frame of the present invention, including using a titanium-aluminum composite strip 1 formed by connecting two layers of titanium and aluminum composite materials as the frame 2 of the mobile phone middle frame, and using an aluminum plate 3 as the inner plate material connected to the frame 2 of the mobile phone middle frame; wherein, the titanium layer 4 in the titanium-aluminum composite strip 1 is located on the outside of the frame 2 of the mobile phone middle frame, and the aluminum layer 5 in the titanium-aluminum composite strip 1 is located on the inside of the frame 2 of the mobile phone middle frame; the frame 2 of the mobile phone middle frame and the inner plate material of the mobile phone middle frame are connected by friction stir welding.

[0043] Preferably, the titanium-aluminum composite strip 1 is formed by rolling and composite connecting a titanium strip as the titanium layer 4 and an aluminum strip as the aluminum layer 5 .

[0044] Preferably, the frame 2 of the mobile phone middle frame is a combined frame formed by splicing four titanium-aluminum composite strips 1.

[0045] Among them, two of the four titanium-aluminum composite bars 1 are straight titanium-aluminum composite bars 6, and the other two of the four titanium-aluminum composite bars 1 are bent titanium-aluminum composite bars 7 formed by bending the titanium-aluminum composite bars. The two straight titanium-aluminum composite bars 6 are arranged in parallel and spaced apart, and the two ends of the two bent titanium-aluminum composite bars 7 are respectively connected to the two ends of the two straight titanium-aluminum composite bars 6, thereby forming the frame 2 of the middle frame of the mobile phone.

[0046] In this embodiment, the thickness of the frame 2 of the mobile phone middle frame and the thickness of the aluminum plate 3 are set to be the same.

[0047] A titanium-aluminum composite mobile phone middle frame processing process includes the following steps:

[0048] (1) Grinding to remove burrs: Grinding is used to remove burrs on the two outer surfaces of the junction of the titanium and aluminum layers.

[0049] (2) Cutting to length and bending: The titanium-aluminum composite strip 1 is cut to a set length to make four titanium-aluminum composite strips, and two of the titanium-aluminum composite strips are bent to obtain two straight titanium-aluminum composite strips 6 and two bent titanium-aluminum composite strips 7;

[0050] (3) Finishing: trimming the front and rear surfaces of the bent portion of the bent titanium-aluminum composite strip 7 to remove the increased thickness of the bent portion caused by the bending;

[0051] (4) Assembly and welding: four titanium-aluminum composite strips 1 are assembled with the aluminum plate 3 so that the four titanium-aluminum composite strips 1 are spliced ​​on the outside of the aluminum plate 3 to form a frame 2 on the outer periphery of the aluminum plate 3, thereby forming a spliced ​​assembly of the mobile phone middle frame. Then, friction stir welding is used to weld the titanium-aluminum composite strips 1 and the aluminum plate 3 connected to each other in the spliced ​​assembly together to obtain an assembled welded body of the mobile phone middle frame;

[0052] (5) Machining: The upper and lower surfaces of the assembled welded body are polished and smoothed, and then CNC machining is performed to produce the finished mobile phone middle frame.

[0053] Preferably, during the trimming process in step (3), the processing equipment used is a double-sided grinder or a CNC machine tool.

[0054] Preferably, during the assembly welding in step (4), the friction stir welding starts from a joint 8 between the straight titanium-aluminum composite strip 6 and the bent titanium-aluminum composite strip 7, and then welds along the periphery of the connection between the frame of the mobile phone middle frame and the inner plate of the mobile phone middle frame, and then exits from the joint 8 or exits from the aluminum plate 3 which is the area to be removed for subsequent CNC processing.

[0055] In this embodiment, during the assembly welding in step (4), a welding positioning tool 9 is used to place the four titanium-aluminum composite strips 1 and the aluminum plate 3 in the welding positioning tool 9 for positioning and fixing before the friction stir welding is performed.

[0056] Preferably, the welding positioning tool 9 includes a base 10, a positioning groove 11 arranged on the plane of the base 10, and the assembled assembly of the mobile phone middle frame is positioned as a whole in the positioning groove 11 of the base 10; a number of automatic advance and retreat clamping devices 12 for clamping and fixing the outer edge of the frame 2 are also arranged around the plane of the base 10, and a vacuum adsorption device 13 for fixing the aluminum plate 3 by vacuum adsorption is also provided in the middle part of the bottom of the positioning groove 11 on the base 10; during the assembly welding in step (4), an XYZ three-dimensional CNC friction stir welding machine is used to perform the friction stir welding.

[0057] Preferably, the automatic advance and retreat pressing device 12 includes a pressure plate 28 movably arranged above the base 10, a guide column 29 uprightly arranged on the upper end surface of the base 10, a cylinder mounting hole 30 arranged on the base 10 in the up and down directions, and a cylinder 31 fixed to the lower end of the base 10, the upper part of the cylinder mounting hole 30 is provided with an expansion hole, and a compression spring 32 is provided in the expansion hole. The pressure plate 28 is respectively provided with a waist-shaped hole 33 and an obliquely arranged guide hole, and the front end of the piston rod of the cylinder 31 passes through the cylinder mounting hole 30, the inner hole of the compression spring 32 and the waist-shaped hole 33 in turn, and is connected to a pressure head 34 for pressing the pressure plate 28. The guide column 29 is tilted toward the outer side of the base 10, and the guide hole on the pressure plate 28 is sleeved on the guide column 29 and is slidably connected to the guide column 29.

[0058] Above-mentioned oil cylinder 31 also can adopt air cylinder to replace.For convenient control, the electromagnetic valve that is used to control oil cylinder or air cylinder is connected to control system respectively.

[0059] When the piston rod of the oil cylinder 31 moves upward, driving the pressure head at its front end to lift upward, the pressure plate 28 rises upward and outward along the inclined guide column 29 under the action of the compression spring 32, and the workpiece (the assembled component of the mobile phone middle frame) can be loaded and unloaded without interfering with the pressure plate 28.

[0060] As a further improvement of this embodiment, a first annular groove 14 is provided on the bottom plane of the positioning groove 11 of the base 10 and directly opposite to the position of the welding seam. A friction stir welding temperature equalization compensator 15 is built into the first annular groove 14 for heating the back of the weld to equalize the temperature of the upper and lower positions of the weld.

[0061] Preferably, the friction stir welding temperature equalization compensator 15 includes an annular magnet 16 installed in the first annular groove 14 and adapted to the first annular groove 14, a second annular groove 17 opened on the annular magnet 16 and opening upward, and an annular copper tube 18 arranged in the second annular groove 17, the annular copper tube 18 is provided with a slit 19 for disconnecting the annular copper tube 18, and a plug 20 is provided at the mouth of the slit 19 of the annular copper tube 18; a pair of electrode copper tubes 21 are led out downward from both sides of the annular copper tube 18 near the slit 19, the interior of the electrode copper tube 21 is connected to the interior of the annular copper tube 18, the pair of electrode copper tubes 21 pass downward through the base 10 and are connected to an external industrial frequency power supply, and cooling circulating water is passed through the interior of the electrode copper tube 21.

[0062] After the workpiece (the assembled components of the mobile phone middle frame) is positioned and clamped in the welding positioning tool 9, the control system turns on the industrial frequency power supply of the friction stir welding temperature equalization compensator 15 to realize directional magnetic induction heating of the upper workpiece. It cooperates with the friction stir welding, which is beneficial to improve the uniformity of the upper and lower temperature of the weld between the frame 2 and the aluminum plate 3 and the stability of the welding temperature, thereby overcoming the disadvantage of uneven upper and lower temperatures that may exist when using friction stir welding alone, and is beneficial to further improve the stability of welding quality.

[0063] Preferably, the vacuum adsorption device 13 includes a concave countersunk hole 22 provided on the bottom plane of the positioning groove 11 in the middle part, a sealing annular groove 23 provided on the bottom plane of the positioning groove 11 and located between the first annular groove 14 and the concave countersunk hole 22, an annular sealing ring 24 installed in the sealing annular groove 23, and a vacuum adsorption hole 25 provided on the base 10 and connected to the concave countersunk hole 22. The vacuum adsorption hole 25 is connected to a vacuum pumping device via a vacuum adsorption pipeline 26. The vacuum pumping device is connected to a control system.

[0064] Preferably, the electrode copper tube 21 is an electrode copper tube with a rectangular cross-sectional shape, and the upper end surface of the electrode copper tube 21 with a rectangular cross-sectional shape is lower than the upper end surface of the annular magnetic conductor 16 .

[0065] In this embodiment, a robot is also provided for automatically installing and positioning the assembled components of the mobile phone middle frame into the welding positioning tool 9 before welding, and removing the assembled welded body of the mobile phone middle frame from the welding positioning tool 9 after welding.

[0066] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A titanium-aluminum composite mobile phone middle frame processing technology, characterized in that: A titanium-aluminum composite strip formed by connecting two layers of titanium and aluminum composite materials is used as the frame of the mobile phone middle frame, and an aluminum plate is used as the inner plate connected to the frame of the mobile phone middle frame; wherein, the titanium layer in the titanium-aluminum composite strip is located on the outer side of the frame of the mobile phone middle frame, and the aluminum layer in the titanium-aluminum composite strip is located on the inner side of the frame of the mobile phone middle frame; the frame of the mobile phone middle frame and the inner plate of the mobile phone middle frame are connected by friction stir welding.

2. The titanium-aluminum composite mobile phone middle frame processing process according to claim 1, characterized in that: The frame of the mobile phone middle frame is a combined frame formed by splicing four titanium-aluminum composite strips.

3. The titanium-aluminum composite mobile phone middle frame processing process according to claim 2, characterized in that: Two of the four titanium-aluminum composite bars are straight titanium-aluminum composite bars, and the other two of the four titanium-aluminum composite bars are bent titanium-aluminum composite bars formed by bending the titanium-aluminum composite bars. The two straight titanium-aluminum composite bars are arranged in parallel and spaced apart, and the two ends of the two bent titanium-aluminum composite bars are respectively connected to the two ends of the two straight titanium-aluminum composite bars, thereby forming the border of the middle frame of the mobile phone.

4. A process for processing a titanium-aluminum composite mobile phone middle frame according to any one of claims 1 to 3, characterized in that: The steps include: (1) Grinding to remove burrs: Grinding is used to remove burrs on the two outer surfaces of the junction of the titanium and aluminum layers. (2) Cutting to length and bending: The titanium-aluminum composite strip is cut to a set length to make four titanium-aluminum composite strips, and two of the titanium-aluminum composite strips are bent to obtain two straight titanium-aluminum composite strips and two bent titanium-aluminum composite strips; (3) Finishing: trimming the front and rear surfaces of the bent portion of the bent titanium-aluminum composite strip to remove the increased thickness of the bent portion caused by the bending; (4) Assembly and welding: four titanium-aluminum composite strips are assembled with the aluminum plate so that the four titanium-aluminum composite strips are spliced ​​on the outside of the aluminum plate to form a frame around the aluminum plate, forming a spliced ​​assembly of the mobile phone middle frame. Then, friction stir welding is used to weld the titanium-aluminum composite strips and the aluminum plate connected to each other in the spliced ​​assembly together to obtain an assembled welded body of the mobile phone middle frame. (5) Machining: The upper and lower surfaces of the assembled welded body are polished and smoothed, and then CNC machining is performed to produce the finished mobile phone middle frame.

5. The titanium-aluminum composite mobile phone middle frame processing process according to claim 1, characterized in that: During the trimming process in step (3), the processing equipment used is a double-sided grinder or a CNC machine tool.

6. The titanium-aluminum composite mobile phone middle frame processing process according to claim 4, characterized in that: During the assembly welding in step (4), the friction stir welding starts from a joint between the straight titanium-aluminum composite strip and the bent titanium-aluminum composite strip, and then welds along the periphery of the connection between the border of the mobile phone middle frame and the inner plate of the mobile phone middle frame, and then exits from the joint or exits from the aluminum plate that is the area to be removed during subsequent CNC processing.

7. The titanium-aluminum composite mobile phone middle frame processing process according to claim 4, characterized in that: During the assembly and welding in step (4), a welding positioning tool is used to place the four titanium-aluminum composite strips and the aluminum plate in the welding positioning tool for positioning and fixing before the friction stir welding is performed.

8. The titanium-aluminum composite mobile phone middle frame processing process according to claim 7, characterized in that: The welding positioning tooling includes a base and a positioning groove arranged on the upper plane of the base, and the assembled components of the mobile phone middle frame are positioned as a whole in the positioning groove of the base; a number of automatic advance and retreat pressing devices for pressing and fixing the outer edge of the frame are also arranged around the upper plane of the base, and a vacuum adsorption device for fixing the aluminum plate by vacuum adsorption is also arranged in the middle part of the bottom of the positioning groove on the base; during the assembly welding in step (4), an XYZ three-dimensional CNC friction stir welding machine is used to perform the friction stir welding.

9. The titanium-aluminum composite mobile phone middle frame processing process according to claim 8, characterized in that: A first annular groove is provided on the bottom plane of the positioning groove of the base and is located directly opposite the welding seam. A friction stir welding temperature equalization compensator is built into the first annular groove for heating the back of the weld to equalize the temperature of the upper and lower positions of the weld.

10. The titanium-aluminum composite mobile phone middle frame processing process according to claim 9, characterized in that: A robot is also provided for automatically installing and positioning the assembled components of the mobile phone middle frame into the welding positioning tool before welding, and removing the assembled welded body of the mobile phone middle frame from the welding positioning tool after welding.

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