Machining method for reducing roughness of metal shell and metal shell

Abstract

The invention relates to a machining method for reducing the roughness of a metal shell and the metal shell. The technical problem that an existing metal shell is unreasonable in machining design is solved. The machining method for reducing the roughness of the metal shell comprises the following steps that S1, the metal shell is fixed through a vacuum adsorption clamp, so that one surface of the metal shell in the thickness direction faces upwards, and the peripheral face of the metal shell is exposed relative to the vacuum adsorption clamp; s2, machining the metal shell in the S1, wherein the machining comprises rough machining and finish machining which are sequentially carried out on the surface; the rough machining comprises large-allowance cutting machining, semi-finish machining and finish machining which are sequentially carried out, and the cutting allowance is sequentially reduced; the finish machining comprises contour line deep machining and spiral feeding type deep machining which are sequentially carried out. According to the machining method for reducing the roughness of the metal shell, the grinding efficiency is improved, meanwhile, the yield is improved, and manpower is saved.

Description

Technical Field

[0001] The invention belongs to the field of metal shell processing and relates to a processing method for reducing the roughness of a metal shell and the metal shell. Background Art

[0002] With the continuous development of mobile terminal technology, the application of electronic devices such as smart phones, PDAs, and smart watches has become extremely common and has become an important part of people's work and life. The shell of electronic devices usually adopts a metal back shell structure. The metal appearance parts have extremely complex product requirements. At the same time, the product can leave a high-end impression on the user while being fashionable, beautiful and generous.

[0003] The traditional processing method has rough knife marks and the shape is easily distorted, and it is difficult to achieve fine polishing in one polishing. Summary of the invention

[0004] The purpose of the present invention is to provide a processing method for reducing the roughness of a metal shell and a metal shell in view of the above problems existing in the prior art.

[0005] The purpose of the present invention can be achieved by the following technical solutions: The processing method for reducing the roughness of the metal shell comprises the following steps: S1. Fixing the metal shell with a vacuum adsorption fixture so that one surface of the metal shell in the thickness direction faces upward and the outer peripheral surface of the metal shell is exposed relative to the vacuum adsorption fixture; S2, machining the metal shell in S1, wherein the machining includes rough machining and fine machining performed sequentially on the surface; the rough machining includes large-allowance cutting, semi-finishing and finishing machining performed sequentially with decreasing cutting allowances; the finishing includes contour depth machining and spiral-feeding deep machining performed sequentially; and the machining also includes lateral cutting of the outer peripheral surface; S3, polishing the outer peripheral surface, the large plane, and the arc-shaped convex surface connecting the outer peripheral surface and the large plane of the metal shell after the machining in S2, the outer peripheral surface and the arc-shaped convex surface are polished by a ceramic carbon fiber brush respectively, and the large plane is polished by sponge sandpaper, so as to obtain the metal shell.

[0006] Furthermore, in the above S2, the large-residue cutting process uses a roughing cutter of 4300-4800 / pcs, the semi-finishing process uses a round-nose cutter of 5700-6300 / pcs, and the finishing process uses a profiling cutter of 2100-2300 / pcs.

[0007] Furthermore, the cutting amount of the large-residue cutting process is 2.8-3.2 mm, the cutting amount of the semi-finishing process is 0.10-0.20 mm, and the cutting amount of the finishing process is 0.01-0.05 mm.

[0008] Furthermore, in the above S2, the contour depth processing uses a profiling ball end milling cutter, and the profiling ball end milling cutter gradually cuts the material along the contour along the set spacing and on the corresponding set number of layers.

[0009] Furthermore, in the above S2, the spiral cutting deep processing adopts a contoured ball head milling cutter, and the contoured ball head milling cutter cuts along the path of the spiral mosquito coil.

[0010] Furthermore, the spiral cutting deep processing obtains the tool diameter, cutting speed, radius of the cutting spiral and cutting pitch of the contour ball end milling cutter according to the material properties of the metal shell.

[0011] Further, in the above S3, the ceramic carbon fiber brush contacts the outer peripheral surface of the metal shell and the ceramic carbon fiber brush walks a circular path for polishing.

[0012] Furthermore, in the above S3, the ceramic carbon fiber brush contacts the arc-shaped convex surface of the metal shell and the ceramic carbon fiber brush walks at least two circles of annular paths with unequal diameters for polishing.

[0013] Furthermore, in the above S3, the sponge sandpaper contacts the large plane and the sponge sandpaper follows the path of the spiral mosquito coil for polishing.

[0014] The present invention also provides a metal shell, which is manufactured by the processing method for reducing the roughness of the metal shell.

[0015] Compared with the prior art, this processing method for reducing the roughness of the metal shell has the following advantages: 1. Introducing CNC in-machine polishing to improve grinding efficiency and yield, saving manpower, saving multiple cleaning and appearance inspection process links between machining and polishing, reducing the three damages caused by the turnover of processed parts and improving the process yield.

[0016] 2. By using three types of tools in rough machining to reduce the cutting amount in sequence, the accuracy of rough machining can be improved, the frequency of tool replacement can be reduced, the generation of debris can be reduced, and the machining marks on the surface of the metal shell can be more refined, reducing the surface roughness.

[0017] 3. First, let the tool gradually cut the material along the contour line through the finishing process. This will make the cutting process smoother, reduce the unevenness of the surface, ensure the uniform depth of each ring cut, reduce the surface roughness, and reduce the cutting resistance of spiral cutting deep processing. Then, through spiral cutting deep processing, the frequent start and stop and reversal of the tool during the processing process can be avoided, and the vibration and marks caused by acceleration changes can be reduced, thereby improving the surface smoothness.

[0018] 4. Use ceramic fiber brush and sponge sandpaper to polish the outer surface of the metal shell, the arc-shaped convex surface connecting the outer surface and the large plane, and the large plane in turn, effectively remove the knife marks on the surface of the metal shell, and polish from the outside to the inside to improve the polishing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic flow chart of a processing method for reducing the roughness of a metal casing provided by the present invention.

[0020] Figure 2 for Figure 1 Schematic diagram of the rough processing process for reducing the roughness of the metal shell.

[0021] Figure 3 for Figure 1 Schematic diagram of the finishing process for reducing the roughness of the metal casing.

[0022] Figure 4 for Figure 1 Schematic diagram of the polishing process for reducing the roughness of the metal shell.

[0023] Figure 5 for Figure 1 Schematic diagram of the polishing motion trajectory for reducing the roughness of the metal shell.

[0024] Figure 6 A metal shell provided by the present invention is schematically shown Figure 1 .

[0025] Figure 7 A metal shell provided by the present invention is schematically shown Figure 2 .

[0026] In the figure, 11 is the outer peripheral surface; 12 is the arc-shaped convex surface; 13 is the large flat surface. DETAILED DESCRIPTION

[0027] Example 1, please refer to Figure 1 , which is a schematic diagram of a processing method for reducing the roughness of a metal shell provided by the present invention.

[0028] In this embodiment, the quality and characteristics of the raw materials of the metal shell should be selected from materials with relatively uniformity, few impurities and moderate hardness, such as 6 series or 7 series aviation grade aluminum alloy. In order to improve the processing efficiency, the shape of the raw materials or the cut sheet of the metal shell to be processed tends to be rectangular blocks, round blocks, oval blocks and other structures, which are suitable for the use scenarios of the metal shell. In this embodiment, the processing process of the metal shell to be processed in a rectangular block shape is described in detail.

[0029] The processing method for reducing the roughness of a metal shell comprises the following steps: In step S1, a vacuum adsorption fixture is used to fix the metal shell so that one surface of the metal shell in the thickness direction faces upward and the outer peripheral surface 11 of the metal shell is exposed relative to the vacuum adsorption fixture; In this embodiment, the vacuum adsorption fixture is a carrier platform, and a plurality of adsorption holes are arranged at intervals on the carrier platform. The metal shell to be processed is placed on the carrier platform, and the built-in cylinder provides negative pressure suction holes for the adsorption holes. The vacuum suction fixture can provide uniform clamping force, reduce vibration and displacement during processing, and thus help improve processing accuracy and surface quality. Moreover, one of the surfaces in the thickness direction of the metal shell and the outer peripheral surface 11 of the metal shell are both processing surfaces of the metal shell. The processing surface is in an exposed state, which is helpful for setting the cutting path of the tool and improving processing efficiency.

[0030] See also Figures 2 to 3 In step S2, the metal shell in S1 is machined. The machining is performed on a CNC lathe. The machining includes rough machining and fine machining of the surface in sequence. The tool to be used can be added to the rotating tool holder on the CNC lathe in advance for use.

[0031] In this embodiment, rough machining includes large allowance cutting, semi-finishing and finishing, which are performed in sequence and the cutting allowance decreases in sequence. Rough machining can quickly remove excess material to a near-final size, and this stage mainly focuses on the shape formation of the metal shell rather than the surface quality.

[0032] In this embodiment, a rough milling cutter of 4300-4800 / pcs is used for large-allowance cutting. In the actual processing process, the rough milling cutter generally needs to be stopped after being used to 4500 / pcs to observe the tool wear and replace the tool in advance to ensure the processing efficiency of the rough milling cutter. If the tool wear condition is good and continues to be used, the maximum service life of the rough milling cutter shall not exceed 4800 / pcs.

[0033] In other embodiments, in order to increase the cutting efficiency of large-residue cutting, the cutting speed of the roughing cutter can be increased, but this will also accelerate the wear rate of the tool. In this case, the roughing cutter is generally replaced in advance when it is used to 4300 / pcs.

[0034] In this embodiment, the cutting amount of the large excess cutting process is 2.8-3.2mm. In this embodiment, the metal shells to be processed are all of the size after the cutting process. According to the finished size of the metal shell, the cutting amount of the large excess cutting process is preset to 3mm, and the double-sided cutting is 6mm. In this process, the chips generated by the large excess cutting process should be continuous, which can effectively avoid the generation of large particles of debris and cause scratches on the surface of the metal shell.

[0035] In other embodiments, when the single-side margin of the metal shell to be processed is 3.3-3.4 mm, or a notch appears on the edge of the metal shell to be processed, the cutting amount of the large-margin cutting process can be increased to a maximum of 3.2 mm to ensure the integrity of the chips and avoid the problem of breakage in the middle.

[0036] In other embodiments, when the single-side margin of the metal shell to be processed is within 3 mm, the cutting amount of the large-margin cutting process can be set to 2.8 mm to ensure that there is still a suitable margin for subsequent semi-finishing and finishing for more precise cutting work.

[0037] In this embodiment, a round nose cutter with a cutting speed of 5700-6300 / pcs is used for semi-finishing. In the actual processing, the round nose cutter is generally replaced after being used for 6000 / pcs, and its maximum life shall not exceed 6300 / pcs.

[0038] In other embodiments, when the hardness of the metal shell to be processed is relatively hard or the semi-finishing cutting speed is increased, the service life of the round nose cutter can be shortened to 5700 / pcs before the tool is replaced.

[0039] In this embodiment, the cutting amount of semi-finishing is 0.10-0.20 mm. Usually, the cutting allowance of the preceding large-allowance cutting process is within 0.20 mm. The cutting amount of semi-finishing is preset to 0.15 mm, and also provides a suitable chip allowance for subsequent finishing.

[0040] In other embodiments, semi-finishing is used as an intermediate supplementary cutting amount between large-addition cutting and finishing, and the cutting amount of semi-finishing can be increased to 0.20 mm. Alternatively, according to the hardness of the metal shell to be processed, in order to avoid tool breakage during the semi-finishing process, the cutting amount of large-addition cutting and the cutting amount of semi-finishing are increased and reduced to complement each other, and the minimum cutting amount of semi-finishing is 0.10 mm.

[0041] In the present embodiment, the finishing process uses a 2100-2300 / pcs profiling knife. During the finishing process, the contour of the metal shell to be processed is processed close to the size of the finished metal shell. In the actual processing process, the profiling knife is usually replaced after using 2200 / pcs, and can be adjusted within the range of 2100-2300 / pcs according to the process difficulty of the finishing process. In the present embodiment, the cutting amount of the finishing process is 0.01-0.05mm. The finishing process makes the knife marks of the metal shell more refined and reduces the surface roughness. The cutting amount of the finishing process is carried out according to the cutting allowance retained by the semi-finishing process. The minimum cutting amount is 0.01mm, ensuring that each cutting plane after roughing is finished and the processing quality after roughing is maintained. The maximum cutting amount is 0.05mm, so as to avoid excessive cutting amount causing the tool to break.

[0042] By using three types of tools in rough machining to reduce the cutting amount in sequence, the accuracy of rough machining is improved, while the generation of debris is reduced, eliminating multiple cleaning steps between machining and polishing, and making the machining marks on the surface of the metal shell more refined, reducing the surface roughness.

[0043] In this embodiment, machining also includes lateral cutting of the outer peripheral surface 11. The lateral cutting is generally performed before the large-residue cutting. The cutting amount of the lateral cutting is 12.0-13.5 mm. According to the process requirements, the metal shell can be cut on one side or both sides. The processing efficiency can be greatly improved by lateral cutting. When the cutting amount for lateral cutting is less than 12.0 mm, the large-residue cutting operation can be added and repeated 1-2 times to achieve the purpose of lateral cutting. When the single-sided cutting amount for lateral cutting exceeds 13.5 mm, it is sent back to the cutting process to recycle the cutting allowance to avoid waste of cutting materials.

[0044] See also Figure 3In step S2, finishing includes contour line depth processing and spiral tool-feeding deep processing performed in sequence; finishing processes the metal shell to the required 3D shape, and the contour is controlled within ±0.02. Specifically, the contour line depth processing uses a profiling ball head milling cutter, which gradually cuts the material along the set spacing and on the corresponding set number of layers with contour lines. This method allows the tool to gradually cut the material along the contour line, making the cutting process more stable and reducing the unevenness of the surface. The use of contour line processing can ensure that the depth of each ring cut is uniform and reduce the surface roughness. It is necessary to reasonably set the spacing and number of layers of the contour lines according to the shape and size of the shell. In this embodiment, the residual height of the metal shell shape after contour line processing can be set at 0.06mm to avoid mutual interference between adjacent tool paths, and the residual height of the metal shell shape is easier to form a bevel or arc surface in the subsequent spiral tool-feeding deep processing. In this embodiment, an arc convex surface 12 is formed after finishing.

[0045] In this embodiment, the spiral cutting deep processing uses a profiling ball head milling cutter, which cuts along the path of the spiral mosquito coil. This method can avoid frequent start-stop and reversal of the tool during processing, reduce vibration and traces caused by acceleration changes, and thus improve surface smoothness. The spiral cutting deep processing obtains the tool diameter, cutting speed, radius of the cutting spiral, and pitch of the profiling ball head milling cutter according to the material properties of the metal shell to achieve the best processing effect.

[0046] During the finishing process of step S2, try to avoid multiple passes of the tool in the same area, because repeated passes may cause tool marks and over-cutting on the surface, increasing surface roughness. When planning the tool path, accurately calculate the range of each cutting area and the tool's movement trajectory to ensure that the tool can complete the processing of each area at one time. When it is impossible to avoid repeated passes during finishing, the feed speed and cutting depth can be appropriately reduced to reduce the impact on the processed surface.

[0047] In addition, in the process of processing rectangular block-shaped metal shells, rounding technology is usually required. Specifically, at the corners and joints of the tool path, due to the change in the movement direction of the tool, stress concentration and vibration are easily generated, resulting in increased surface roughness. In order to solve this problem, arc transition technology can be used when setting the tool path to make the tool movement smoother at corners and joints. The movement trajectory of the tool at the corner is arc-shaped, and the R angle of its movement trajectory is between R2-R10, which reduces stress concentration and vibration. In addition, the spline curve transition method can also be used to make the movement trajectory of the tool smoother, etc., and the same technical effect can be achieved.

[0048] It should also be noted that the first trial of machining should be run at a low speed, and the cutting speed, feed speed and cutting depth should be set to a lower value of 10%-50%. The cutting speed can be set to 10%-50% of the normal processing speed. This is to safely observe the operation of the machine tool and the tool and the cutting status in the initial stage. Check the shape and color of the chips. Normal chips should be continuous. When the chips are broken, pay attention to the sound during the cutting process. A steady cutting sound indicates that the parameter setting is more reasonable, while a sharp noise may mean that the tool is vibrating or the cutting force is too large, that is, the cutting parameters are not suitable or the tool is worn. Replace the tool in time or adjust the parameters gradually. When the cutting process is smooth, the cutting speed and feed speed can be appropriately increased, but the amplitude of each adjustment should not be too large, generally not more than 10-15%, and slowly adjust to the best processing efficiency.

[0049] During machining, the machining environment needs to be kept clean to prevent dust and impurities from entering the machining area. A dust suction device is provided on one side of the CNC lathe, and the output end of the dust suction device acts on the outer peripheral surface 11 of the metal shell or moves with the machining tool. The dust and impurities are sucked by the blowing output or adsorption output of the dust suction device to avoid scratches and wear on the machining surface.

[0050] See also Figure 4-Figure 6 In step S3, the outer peripheral surface 11, the large plane 13, and the arcuate convex surface 12 connecting the outer peripheral surface 11 and the large plane 13 of the metal shell machined in step S2 are polished, and the polishing process is also completed in a CNC lathe, wherein the outer peripheral surface 11 and the arcuate convex surface 12 are polished by a ceramic carbon fiber brush, and the large plane 13 is polished by sponge sandpaper, so as to obtain a metal shell.

[0051] Specifically, a ceramic carbon fiber brush of a corresponding diameter is used according to the size of the outer peripheral surface 11. In this embodiment, a ceramic carbon fiber brush with a diameter of 10 mm is used to contact the outer peripheral surface 11 of the metal shell, and the ceramic carbon fiber brush walks a circular path for polishing. The ceramic fiber brush and the outer peripheral surface 11 of the metal shell are rubbed at high speed to remove the edge knife marks, so that there is no edge collapse and knife marks after fine polishing.

[0052] In step S3, a ceramic carbon fiber brush with a larger diameter than the pre-polishing is used according to the size of the arc surface of the metal shell. In this embodiment, a ceramic carbon fiber brush with a diameter of 80 mm is used to contact the arc convex surface 12 of the metal shell, and the ceramic carbon fiber brush walks at least two circles of annular paths with unequal diameters for polishing. During the rotation process, the arc surface of the metal shell and the large plane 13 are rubbed at high speed to remove the knife marks and polishing marks, and the polishing marks are received on the large plane 13.

[0053] In step S3, the sponge sandpaper contacts the large plane 13 and follows the path of the spiral mosquito coil for polishing. The sponge sandpaper rubs against the product at high speed, and the large surface knife marks and polishing marks are removed by cutting the consumables to achieve a consistent rough polishing effect.

[0054] Example 2, please refer to Figure 6 to Figure 7 The present invention also provides a metal shell, which is made by the processing method for reducing the roughness of the metal shell. In this embodiment, the metal shell is applied to a laptop shell, which is usually assembled in terminal devices such as mobile phones, tablets, laptops, smart watches, etc. Specifically, the metal shell can be a mobile phone back shell, a tablet back shell, a laptop screen back shell, etc.

[0055] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A processing method for reducing the roughness of a metal shell, characterized in that: The following steps are involved: S1. Fixing the metal shell with a vacuum adsorption fixture so that one surface of the metal shell in the thickness direction faces upward and the outer peripheral surface of the metal shell is exposed relative to the vacuum adsorption fixture; S2, machining the metal shell in S1, wherein the machining includes rough machining and fine machining performed sequentially on the surface; the rough machining includes large-allowance cutting, semi-finishing and finishing machining performed sequentially with decreasing cutting allowances; the finishing includes contour depth machining and spiral-feeding deep machining performed sequentially; and the machining also includes lateral cutting of the outer peripheral surface; S3, polishing the outer peripheral surface, the large plane, and the arc-shaped convex surface connecting the outer peripheral surface and the large plane of the metal shell after the machining in S2, the outer peripheral surface and the arc-shaped convex surface are polished by a ceramic carbon fiber brush respectively, and the large plane is polished by sponge sandpaper, so as to obtain the metal shell.

2. The method for reducing the roughness of a metal shell according to claim 1, characterized in that: In the above S2, the large-residue cutting process uses a roughing cutter of 4300-4800 / pcs, the semi-finishing process uses a round nose cutter of 5700-6300 / pcs, and the finishing process uses a profiling cutter of 2100-2300 / pcs.

3. The method for reducing the roughness of a metal shell according to claim 2, characterized in that: The cutting amount of the large-residue cutting process is 2.8-3.2 mm, the cutting amount of the semi-finishing process is 0.10-0.20 mm, and the cutting amount of the finishing process is 0.01-0.05 mm.

4. The method for reducing the roughness of a metal shell according to claim 1, characterized in that: In the above S2, the contour depth processing adopts a profiling ball end milling cutter, and the profiling ball end milling cutter cuts the material step by step along the contour along the set spacing and on the corresponding set number of layers.

5. The method for reducing the roughness of a metal shell according to claim 1, characterized in that: In the above S2, the spiral cutting deep processing adopts a contour ball end milling cutter, and the contour ball end milling cutter cuts along the path of the spiral mosquito coil.

6. The method for reducing the roughness of a metal shell according to claim 5, characterized in that: The spiral cutting deep processing obtains the tool diameter, cutting speed, radius of the cutting spiral and cutting pitch of the profiling ball end milling cutter according to the material properties of the metal shell.

7. The method for reducing the roughness of a metal shell according to claim 1, characterized in that: In the above S3, the ceramic carbon fiber brush contacts the outer peripheral surface of the metal shell and the ceramic carbon fiber brush walks a circular path for polishing.

8. The method for reducing the roughness of a metal shell according to claim 1, characterized in that: In the above S3, the ceramic carbon fiber brush contacts the arc-shaped convex surface of the metal shell and the ceramic carbon fiber brush walks at least two circles of annular paths with unequal diameters for polishing.

9. The method for reducing the roughness of a metal shell according to claim 1, characterized in that: In the above S3, the sponge sandpaper contacts the large plane and the sponge sandpaper follows the path of the spiral mosquito coil for polishing.

10. A metal housing, characterized in that: The metal shell is made by the processing method for reducing the roughness of the metal shell according to any one of claims 1 to 9.

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