Processing technology for rear cover of folding screen electronic equipment

Abstract

The invention discloses a folding screen electronic equipment rear cover machining process which comprises the steps that S1, glass is cut and thinned once so as to obtain a UTG glass sheet to be subjected to sand blasting, and the UTG glass sheet comprises a part to be subjected to sand blasting and a skirt edge part surrounding the part to be subjected to sand blasting; s2, the UTG glass sheet is loaded into a sand blasting clamp, the part to be subjected to sand blasting is exposed to a sand blasting operation area of sand blasting equipment, the sand blasting clamp shields the skirt edge part, and sand blasting is conducted on the UTG glass sheet; s3, flattening the UTG glass sheet; s4, cutting off the skirt edge part of the flattened UTG glass sheet, and carrying out secondary thinning on the UTG glass sheet; s5, laminating the UTG glass sheets which are thinned for the second time, so as to obtain a glass laminated layer; s6, machining an edge chamfer of the glass lamination by adopting CNC (Computer Numerical Control), and polishing a rabbet body of the glass lamination; and S7, splitting the polished glass lamination into a plurality of UTG glass sheets, performing double-sided protection, and etching edge chamfers of the UTG glass sheets to obtain a finished product.

Description

Technical Field

[0001] The present invention relates to the field of folding screen glass processing technology, and in particular to a folding screen electronic device back cover processing technology for achieving sandblasting of the user surface and chamfering of edge stacking of the back cover of the folding screen electronic device. Background Art

[0002] Flexible ultra-thin glass (UTG) has the advantages of high surface hardness and screen clarity, good light transmission, good wear resistance and high temperature resistance, and has a good touch feel. It can achieve a balance between folding performance and mechanical strength. It is not easy to wrinkle after repeated folding. It can be used as the back cover of a folding screen mobile phone. While meeting the bending requirements of the back cover of a folding screen mobile phone, it can also reduce the weight of the back cover of the mobile phone. However, as the thickness of the flexible ultra-thin glass decreases, while its light transmission performance and flexibility are improved and its weight is reduced, the mechanical strength of the glass decreases, and any impurities and microcracks will have a serious negative impact on the ultra-thin glass. At present, the industry mainly chamfers UTG glass to take into account the strength and toughness of UTG glass. Traditional chamfering processes mostly use laser chamfering, which has high precision and high efficiency and can achieve contactless processing. However, when the thickness of the UTG glass is less than 50μm, the processing accuracy of the laser chamfering is significantly reduced, resulting in insufficient glass yield. In addition, due to the high smoothness of the UTG glass surface, there is a risk of the phone slipping due to unstable grip during use, as well as wear and scratches caused by contact between the phone and foreign objects, which in turn affects the service life of the phone. Summary of the invention

[0003] Based on this, it is necessary to provide a folding screen electronic device back cover processing technology that combines stacking chamfering with sandblasting to improve the strength, toughness, touch and anti-slip performance of UTG glass, avoid wear and scratches on mobile phones, and improve the product sandblasting and chamfering yield rate.

[0004] A folding screen electronic device back cover processing technology, comprising the following steps:

[0005] S1, cutting and thinning the glass once to obtain a UTG glass sheet to be sandblasted, wherein the UTG glass sheet comprises a portion to be sandblasted and a skirt portion surrounding the portion to be sandblasted;

[0006] S2, placing the UTG glass sheet into a sandblasting fixture, exposing the portion to be sandblasted to the sandblasting operation area of ​​the sandblasting equipment, and allowing the sandblasting fixture to cover the skirt portion, and sandblasting the UTG glass sheet;

[0007] S3, smooth the UTG glass sheet;

[0008] S4, cutting off the skirt portion of the smoothed UTG glass sheet, and performing secondary thinning on the UTG glass sheet;

[0009] S5, laminating the UTG glass sheets after the second thinning to obtain a glass laminate;

[0010] S6, CNC machine the edge chamfers of the glass laminate and polish the body of the glass laminate;

[0011] S7. Split the polished glass laminate into several UTG glass sheets, double-side protect and etch the edge chamfers of the UTG glass sheets to obtain finished products.

[0012] In one embodiment, step S1 comprises:

[0013] S11, apply protective oil on both sides of the glass material;

[0014] S12, cutting and chamfering the glass material to obtain a rectangular glass sheet;

[0015] S13, polishing the glass sheet and removing the protective oil on the surface of the glass sheet;

[0016] S14, placing the glass sheet in an etching solution and thinning it to 0.07-0.08 mm to obtain a UTG glass sheet;

[0017] S15. Apply protective oil to the system surface of the UTG glass sheet.

[0018] In one embodiment, the sandblasting fixture comprises:

[0019] A sandblasting base, the sandblasting base comprising a concave base and a convex base which are arranged opposite to each other and snap-fitted, the upper surface of the concave base being provided with a first groove, a side surface of the concave base adjacent to the convex base being provided with a mounting notch, the first groove penetrating the concave base at the side surface where the mounting notch is located; the upper surface of the convex base being provided with a second groove, a side surface of the convex base adjacent to the concave base being provided with a mounting protrusion snap-fitted with the mounting notch, the second groove penetrating the convex base at the side surface where the mounting protrusion is located;

[0020] A positioning frame, the positioning frame comprising a first U-shaped frame embedded in a first groove and fixedly connected to the concave base, and a second U-shaped frame embedded in a second groove and fixedly connected to the convex base, the upper surface of the first U-shaped frame is higher than the upper surface of the concave base, the upper surface of the second U-shaped frame is higher than the upper surface of the convex base, and the first U-shaped frame and the second U-shaped frame together enclose a limiting area for accommodating the UTG glass sheet, and the height of the limiting area is less than or equal to the thickness of the UTG glass sheet; and

[0021] An annular cover plate is pressed and fixed on the upper surfaces of the first U-shaped frame and the second U-shaped frame, and the annular cover plate forms a sandblasting shielding area corresponding to the skirt portion of the UTG glass sheet above the limiting area, and the inner ring area of ​​the annular cover plate forms a sandblasting area corresponding to the portion to be sandblasted of the UTG glass sheet.

[0022] In one of the embodiments, a plurality of first positioning holes and a plurality of first sand leakage holes are provided in the first groove, and a plurality of second positioning holes and a plurality of second sand leakage holes are provided in the second groove; a plurality of third positioning holes corresponding to each first positioning hole and a plurality of first sand leakage gaps corresponding to each first sand leakage hole are provided on the first U-shaped frame, a plurality of fourth positioning holes corresponding to each second positioning hole and a plurality of second sand leakage gaps corresponding to each second sand leakage hole are provided on the second U-shaped frame; a plurality of fifth positioning holes corresponding to each third positioning hole and a fourth positioning hole are provided on the annular cover plate; the sandblasting base also includes a plurality of first mounting screws that sequentially penetrate the fifth positioning hole, the third positioning hole, and the first positioning hole to connect the annular cover plate, the first U-shaped frame and the concave base, and a plurality of second mounting screws that sequentially penetrate the fifth positioning hole, the fourth positioning hole, and the second positioning hole to connect the annular cover plate, the second U-shaped frame and the convex base.

[0023] In one embodiment, the sandblasting fixture also includes at least one baffle for shielding the skirt portion of the UTG glass sheet located in the sandblasting area, the baffle including a horizontal bar mounted astride a concave base or a convex base, and two clamping blocks arranged opposite to each other and fixed at both ends of the horizontal bar, the concave base is provided with two first clamping grooves arranged opposite to each other on the outer side of the first groove, and the convex base is provided with two second clamping grooves arranged opposite to each other on the outer side of the second groove; the two clamping blocks of the baffle are embedded in the two first clamping grooves one by one and are fixedly connected to the annular cover plate by means of limit screws passing through the annular cover plate, or the two clamping blocks of the baffle are embedded in the two second clamping grooves one by one and are fixedly connected to the annular cover plate by means of limit screws passing through the annular cover plate.

[0024] In one embodiment, step S3 comprises:

[0025] S31, remove the protective oil on the surface of the UTG glass sheet system;

[0026] S32. Etch the UTG glass sheet with an alkaline etching solution to smooth the UTG glass sheet.

[0027] In one embodiment, step S5 comprises:

[0028] S51, applying glue between the stacked substrate and the UTG glass sheet or between two UTG glass sheets to form a glue-board composition;

[0029] S52, irradiating the glue-board composition with UV light to cure the glue to form a glue layer;

[0030] S53, baking the glue-board composition after the glue layer is cured;

[0031] S54, repeating steps S51-S53 until a glass laminate consisting of two substrates disposed opposite to each other and a plurality of UTG glass sheets stacked between the two substrates is formed.

[0032] In one embodiment, step S7 includes:

[0033] S71, debonding the glass laminate to separate the glass laminate into a plurality of UTG glass sheets;

[0034] S72, attach protective film on both sides of the UTG glass sheet;

[0035] S73, etching the edge chamfer of the UTG glass sheet using an alkaline etching solution;

[0036] S74. Remove the protective film on the surface of the UTG glass sheet.

[0037] In one embodiment, in step S71, the glass laminate is placed in hot water for debonding.

[0038] In one embodiment, step S74 further includes:

[0039] S75, chemically strengthening the UTG glass sheet to harden the UTG glass sheet;

[0040] S76, placing the strengthened UTG glass sheet in an alkaline etching solution for polishing. After polishing, the surface roughness Sa of the UTG glass sheet is less than 1 nm.

[0041] The back cover processing technology of the folding screen electronic device of the present invention is implemented. The skirt portion of the UTG glass sheet is blocked by a sandblasting fixture, and the skirt portion is removed in subsequent operations. While sandblasting the surface of the UTG glass sheet, improving the anti-slip performance of the glass sheet, reducing the risk of wear and scratching of the glass sheet, and extending the service life of the product, the problem of glass sheet breakage caused by the contact between sandblasting sand particles and the edge of the glass sheet can be avoided. The removal of the skirt portion can also reduce the shelf mark produced after the product is smoothed, and the defective rate of product sandblasting can be reduced; by chamfering and polishing the UTG glass sheets after stacking, the burrs remaining in the CNC processing of the UTG glass sheets can be removed while ensuring that the UTG glass sheets are not broken, thereby ensuring the strength of the UTG glass sheets; by double-sided protection and etching the edge chamfering of the polished UTG glass sheets, the chamfering of UTG glass with a thickness of less than 40 μm can be met, and while improving the strength and toughness of the UTG glass sheets, the yield rate of chamfering processing is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1This is a flow chart of a process for processing a back cover of a folding screen electronic device in one embodiment of the present invention;

[0043] Figure 2 It is a schematic structural diagram of a UTG glass sheet to be sandblasted in one embodiment of the present invention;

[0044] Figure 3 A schematic structural diagram of a sandblasting fixture from one perspective in one embodiment of the present invention;

[0045] Figure 4 A schematic structural diagram of a sandblasting fixture from another perspective in one embodiment of the present invention;

[0046] Figure 5 An exploded view of a sandblasting fixture according to an embodiment of the present invention;

[0047] Figure 6 A cross-sectional structural diagram of a sandblasting fixture in one direction according to an embodiment of the present invention;

[0048] Figure 7 A cross-sectional structural diagram of a sandblasting fixture in one direction according to an embodiment of the present invention;

[0049] Figure 8 A schematic diagram of the cross-sectional structure of a glass laminate in one embodiment of the present invention;

[0050] Fig. 9 It is a flowchart of the back cover processing technology of a folding screen electronic device in one embodiment of the present invention. DETAILED DESCRIPTION

[0051] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0052] Please combine Figure 1-9 The present invention discloses a folding screen electronic device back cover processing technology, which is used to achieve the sandblasting of the user surface of the back cover of the folding screen electronic device and the chamfering of the edge lamination, especially for the glass back cover processing of Apple mobile phones (iPhone) or tablets (iPad). Specifically, the processing technology includes the following steps:

[0053] S1, cutting and thinning the glass once to obtain a UTG glass sheet 10 to be sandblasted, the UTG glass sheet comprising a portion to be sandblasted 101 and a skirt portion 102 surrounding the portion to be sandblasted 101 (the structure of the UTG glass sheet is as shown in FIG. Figure 2shown).

[0054] Further, step S1 includes:

[0055] S11. Apply protective oil to both sides of the glass material.

[0056] The glass material processed in this embodiment is a grind-free glass of model 7418 produced by Corning. In other embodiments, other types of grind-free glass available on the market can also be used. Specifically, protective oil is applied on both sides of the glass material by silk screen printing to avoid damage to the glass surface in subsequent processes. The protective oil used is acid-resistant protective ink of model 4500PN. The thickness of the acid-resistant protective ink applied on one side of the glass is 15-25μm. The model of the silk screen used is 77T. After the acid-resistant protective ink is applied, the glass surface is heated continuously at 175-185°C for 3 minutes to dry the acid-resistant protective ink on the glass surface, and then the glass surface is heated continuously at 175-185°C for 30 minutes to solidify the acid-resistant protective ink on the glass surface.

[0057] S12, cutting and chamfering the glass material to obtain a rectangular glass sheet.

[0058] Specifically, first cut the large piece of glass material so that the glass material is cut into several small pieces of glass to facilitate the subsequent production process. When cutting the glass material, a diamond grinding wheel is used as a cutting wheel to cut the glass material, with a cutting depth of 0.005-0.01mm, a cutting pressure of 1-2MPa, and a cutting wheel feed speed of 35000-60000mm / min. Then a CNC machine is used to process the shape and chamfer of the cut glass so that the shape of the cut glass is roughly processed into the shape required by the customer. When processing the shape and chamfer of the cut glass, rough cutting is performed first, and then fine cutting is performed. The spindle speed during rough cutting and fine cutting is 28000-32000rpm, the rough cutting grinding wheel uses a grinding wheel with a grit number of 400#, and the rough cutting feed speed is 80mm / min, and the fine cutting grinding wheel uses a grinding wheel with a grit number of 800#, and the fine cutting feed speed is 130mm / min.

[0059] S13. Polish the glass sheet and remove the protective oil on the surface of the glass sheet.

[0060] Specifically, firstly, a pig hair brush is used to polish the edge of the glass sheet to remove the sharp edges or burrs generated when CNC processes the glass shape, so as to avoid scratches, broken pieces and other defects in subsequent processes. During polishing, the length of the pig hair brush is 15-30mm, the rotation speed when polishing the long edge of the glass sheet is 1750-1850rpm, and the rotation speed when polishing the short edge of the glass sheet is 400-500rpm. Then, the polished glass sheet is placed in an alkaline solution to remove the protective oil on the surface of the glass sheet to reduce the influence of the protective ink layer formed by the protective oil on the surface of the glass sheet on the precision of the UTG glass thinning by the grinder. When the protective oil is de-plated, the glass sheet is placed in a NaOH solution with a mass fraction of 8-10% and a temperature of 78-82°C, and the de-plating is continued for 14-16 minutes to remove the protective ink layer on the system surface of the glass sheet.

[0061] S14, placing the glass sheet in an etching solution, and thinning it to 0.07-0.08 mm (i.e., 70-80 μm), to obtain a UTG glass sheet.

[0062] Specifically, first use an electronic scale to weigh 45 kg of water, then add 5 kg of NaG and 50 kg of NaOH in batches, stirring while adding until NaG and NaOH are completely dissolved, thereby preparing a mixed solution with a mass fraction of 50% NaOH and a mass fraction of 5% NaG to obtain an etching solution, and then place a glass sheet in the etching solution, and chemically thin the glass sheet at a temperature of 115-125° C. until the thickness of the glass sheet is thinned to 0.07-0.08 mm, thereby achieving one-time thinning of the glass sheet.

[0063] S15. Apply protective oil to the system surface of the UTG glass sheet.

[0064] For the glass sheet etched to 0.07-0.08 mm by alkaline etching, the system surface is screen-printed with protective oil to prevent the subsequent process from damaging the surface. In this embodiment, the protective oil used is the acid-resistant protective ink of model 4500PN, the thickness of the acid-resistant protective ink coated on one side of the glass is 15-25 μm, the model of the screen printing screen used is 77T, and after the acid-resistant protective ink is coated, the glass surface is continuously heated at 175-185°C for 3 minutes to dry the acid-resistant protective ink on the glass surface, and then the glass surface is continuously heated at 175-185°C for 30 minutes to solidify the acid-resistant protective ink on the glass surface.

[0065] It should be noted that the length of the UTG glass sheet to be sandblasted obtained after the processes of cutting, thinning and coating with protective oil needs to be 30 mm longer than the length of the finished product, and the width of the UTG glass sheet to be sandblasted needs to be 30 mm longer than the width of the finished product, wherein the area on the UTG glass sheet to be sandblasted corresponding to the finished product forms a portion to be sandblasted 101, the width of the portion to be sandblasted 101 is 16-20 mm smaller than the width of the UTG glass sheet to be sandblasted, and the length of the portion to be sandblasted 101 is 16-20 mm smaller than the length of the UTG glass sheet to be sandblasted; The area beyond the edge of the finished product forms a skirt portion 102. When laminating, 2mm needs to be cut off on one side. This cut-off portion is also the sandblasting area. Therefore, the length of the portion to be sandblasted 101 needs to be 4.028-4.032mm larger than the length of the finished product, and the width of the portion to be sandblasted 101 needs to be 4.028-4.032mm larger than the width of the finished product. This avoids the problem of partial non-sandblasting on the product due to processing errors, and ensures that the user surface of the final product is a sand surface. The excess size will be removed in the subsequent process of CNC, surface etching, chamfer etching and back polishing after lamination. When sandblasting, the skirt portion 102 is blocked so that the sandblasting equipment only sandblasts the portion to be sandblasted 101 of the glass sheet, avoiding the problem of glass sheet breakage caused by sand particles directly spraying onto the edge of the UTG glass sheet during sandblasting, so as to reduce the defective rate of sandblasting operations.

[0066] S2. Place the UTG glass sheet into the sandblasting fixture 20, expose the portion to be sandblasted 101 to the sandblasting operation area of ​​the sandblasting equipment, and cover the skirt portion 102 with the sandblasting fixture 20 to sandblast the UTG glass sheet.

[0067] Please combine Figure 2-7The sandblasting fixture 20 includes a sandblasting base 100, a positioning frame 200 and an annular cover plate 300. The sandblasting base 100 includes a concave base 110 and a convex base 120 that are relatively arranged and snap-fitted. A first groove 111 is provided on the upper surface of the concave base 110, and a mounting notch 112 is provided on a side of the concave base 110 adjacent to the convex base 120. The first groove 111 penetrates the side of the concave base 110 where the mounting notch 112 is located; a second groove 121 is provided on the upper surface of the convex base 120, and a mounting protrusion 122 snap-fitted with the mounting notch 112 is provided on a side of the convex base 120 adjacent to the concave base 110, and the second groove 121 penetrates the side of the convex base 120 where the mounting protrusion 122 is located. The positioning frame 200 includes a first U-shaped frame 210 embedded in the first groove 111 and fixedly connected to the concave base 110, and a second U-shaped frame 220 embedded in the second groove 121 and fixedly connected to the convex base 120. The upper surface of the first U-shaped frame 210 is higher than the upper surface of the concave base 110, and the upper surface of the second U-shaped frame 220 is higher than the upper surface of the convex base 120. The first U-shaped frame 210 and the second U-shaped frame 220 together form a limiting area 230 for accommodating the UTG glass sheet, and the height of the limiting area 230 is less than or equal to the thickness of the UTG glass sheet. The annular cover plate 300 is pressed and fixed on the upper surfaces of the first U-shaped frame 210 and the second U-shaped frame 220. The annular cover plate 300 forms a sandblasting shielding area corresponding to the skirt portion 102 of the UTG glass piece above the limiting area 230. The inner ring area of ​​the annular cover plate 300 forms a sandblasting area corresponding to the portion to be sandblasted 101 of the UTG glass piece. The setting of the sandblasting shielding area can prevent the edge of the glass piece from being placed in the sandblasting area of ​​the annular cover plate 300, thereby preventing the edge of the glass piece from being impacted by sand particles and causing the glass piece to be broken. Preferably, in this embodiment, the groove depths of the first groove 111 and the second groove 121 are both 4 mm, the thicknesses of the first U-shaped frame 210 and the second U-shaped frame 220 are both 5 mm, and the height of the limiting area 230 is 1 mm. Since the thickness of the UTG glass sheet to be sandblasted is 0.07-0.08 mm, the height of the limiting area 230 can not only meet the limitation of the UTG glass sheet, but also avoid the UTG glass sheet 10 to be sandblasted to be crushed when the annular cover plate 300 is closed. After the sandblasting of the UTG glass sheet is completed, the UTG glass sheet can also be taken away from the sandblasting base 100 by the positioning frame 200 to avoid the UTG glass sheet from breaking when the sheet is taken. In addition, the shape of the first groove 111 is adapted to the shape of the first U-shaped frame 210, and the shape of the second groove 121 corresponds to the shape of the second U-shaped frame 220, that is, the first groove 111 and the second groove 121 are both U-shaped structures to avoid the positioning frame 200 from shaking on the sandblasting base 100.

[0068] In this embodiment, the sandblasting base 100 is designed to be a concave base 110 and a convex base 120 connected by snap-fit ​​connection. After the UTG glass sheet is sandblasted, the snap-fitting parts of the concave base 110 and the convex base 120 are disassembled to separate the concave base 110 and the convex base 120, and then the positioning frame 200 is pushed to make the positioning frame 200 drive the UTG glass sheet to slide out from the sandblasting base 100, so as to avoid the problem of the sandblasting UTG glass sheet being broken due to the method of taking the UTG glass sheet by hand or sucking it with a suction pen. During the assembly process of the sandblasting fixture 20, the concave base 110 and the convex base 120 need to be assembled with the first U-shaped frame 210 and the second U-shaped frame 220 respectively, and then spliced; during the disassembly process of the sandblasting fixture 20, it is just the opposite. The convex base 120 and the concave base 110 need to be disassembled first, and then the components installed on the concave base 110 and the convex base 120 need to be disassembled one by one. The specific process is as follows:

[0069] 1) Clean the concave base 110 and the convex base 120 .

[0070] 2) Assemble the positioning frame 200, and embed the first U-shaped frame 210 and the second U-shaped frame 220 into the first groove 111 of the concave base 110 and the second groove 121 of the convex base 120 respectively, ensuring that the outer edge of the short side of the first U-shaped frame 210 abuts against the inner edge of the short side of the concave base 110, and the outer edge of the short side of the second U-shaped frame 220 abuts against the inner edge of the short side of the convex base 120.

[0071] 3) Slide the UTG glass sheet into the first U-shaped frame 210 along the upper surface of the concave base 110, ensuring that the outer edge of the UTG glass sheet, whose size is adapted to the short side of the sandblasting fixture 20, abuts against the inner edge of the first U-shaped frame 210; or slide the UTG glass sheet into the second U-shaped frame 220 along the upper surface of the convex base 120, ensuring that the outer edge of the UTG glass sheet, whose size is adapted to the short side of the sandblasting fixture 20, abuts against the inner edge of the second U-shaped frame 220.

[0072] 4) The convex base 120 and the concave base 110 are spliced ​​together so that the UTG glass sheet is located between the first U-shaped frame 210 and the second U-shaped frame 220 .

[0073] 5) Cover the annular cover plate 300, ensure that the mounting parts on the annular cover plate 300 are aligned with the mounting parts on the first U-shaped frame 210, the second U-shaped frame 220, the concave base 110 and the convex base 120, and fix the annular cover plate 300, the first U-shaped frame 210, the second U-shaped frame 220, the concave base 110 and the convex base 120 together.

[0074] Furthermore, in the present embodiment, a limit block is provided at the end of the mounting protrusion 122, the width of the limit block is greater than the width of the mounting protrusion 122, a circular arc transition portion is provided at the connection portion between the limit block and the mounting protrusion 122, and the width difference between the limit block and the mounting protrusion 122 is between 1-2 mm. Accordingly, a limit groove adapted to the shape of the limit block is provided in the mounting notch 112. In this way, through the mutual constraint of the limit block and the limit groove, while facilitating the disassembly of the concave base 110 and the convex base 120, displacement between the concave base 110 and the convex base 120 can be avoided when the annular cover plate 300 is installed, thereby reducing the difficulty of assembling the sandblasting fixture 20.

[0075] Further, in one embodiment, a plurality of first positioning holes 113 and a plurality of first sand leakage holes 114 are provided in the first groove 111, and a plurality of second positioning holes 123 and a plurality of second sand leakage holes 124 are provided in the second groove 121; a plurality of third positioning holes 211 corresponding to each of the first positioning holes 113 and a plurality of first sand leakage gaps 212 corresponding to each of the first sand leakage holes 114 are provided on the first U-shaped frame 210, and a plurality of fourth positioning holes 221 corresponding to each of the second positioning holes 123 and a plurality of second sand leakage gaps corresponding to each of the second sand leakage holes 124 are provided on the second U-shaped frame 220. 222; a plurality of fifth positioning holes 310 corresponding to the third positioning holes 211 and the fourth positioning holes 221 are formed on the annular cover plate 300; the sandblasting base 100 also includes a plurality of first mounting screws 320 which are sequentially connected through the fifth positioning holes 310, the third positioning holes 211, and the first positioning holes 113 to connect the annular cover plate 300, the first U-shaped frame 210 and the concave base 110, and a plurality of second mounting screws 330 which are sequentially connected through the fifth positioning holes 310, the fourth positioning holes 221, and the second positioning holes 123 to connect the annular cover plate 300, the second U-shaped frame 220 and the convex base 120. In this embodiment, after the UTG glass sheet is loaded and the various components of the sandblasting fixture 20 are assembled, the annular cover plate 300, the first U-shaped frame 210 and the concave base 110 are fixed by the first mounting screws 320, and the annular cover plate 300, the second U-shaped frame 220 and the convex base 120 are fixed by the second mounting screws 330. This can avoid relative movement of the sandblasting base 100, the positioning frame 200 and the annular cover plate 300 during the sandblasting process, thereby preventing the occurrence of poor sandblasting position problems of the UTG glass sheet, thereby ensuring the sandblasting quality of the UTG glass sheet. In this solution, by providing a first sand leakage gap 212 on the first U-shaped frame 210, providing a second sand leakage gap 222 on the second U-shaped frame 220, providing a first sand leakage hole 114 on the concave base 110, and providing a second sand leakage hole 124 on the convex base 120, the sand-water mixture sprayed during the sandblasting process can flow into the sandblasting pipeline through the above-mentioned sand leakage gap and sand leakage hole for circulation in time, thereby avoiding the problem of poor optical properties of the sandblasted glass caused by the sand-water mixture covering the surface of the glass sheet. Further preferably, in this embodiment, the plurality of first positioning holes 113 and the plurality of first sand leakage holes 114 are respectively evenly distributed in the first groove 111, the plurality of second positioning holes 123 and the plurality of second sand leakage holes 124 are respectively evenly distributed in the second groove 121, the plurality of third positioning holes 211 and the plurality of first sand leakage gaps 212 are respectively evenly distributed on the first U-shaped frame 210, and the plurality of fourth positioning holes 221 and the plurality of second sand leakage gaps 222 are respectively evenly distributed on the second U-shaped frame 220.

[0076] In one embodiment, the sandblasting fixture 20 also includes at least one baffle 400 for shielding the skirt portion 102 of the UTG glass sheet located in the sandblasting area, the baffle 400 includes a horizontal bar 410 straddled on the concave base 110 or the convex base 120, and two clamping blocks 420 arranged oppositely and fixed at both ends of the horizontal bar 410, the concave base 110 is provided with two first clamping grooves 115 arranged oppositely on the outer side of the first groove 111, and the convex base 120 is provided with two second clamping grooves 125 arranged oppositely on the outer side of the second groove 121; the two clamping blocks 420 of the baffle 400 are embedded in the two first clamping grooves 115 one by one and are fixedly connected to the annular cover plate 300 by the limit screws passing through the annular cover plate 300, or the two clamping blocks 420 of the baffle 400 are embedded in the two second clamping grooves 125 one by one and are fixedly connected to the annular cover plate 300 by the limit screws 500 passing through the annular cover plate 300. Preferably, the depth of the first slot 115 and the second slot 125 are both 10 mm to increase the matching area between the baffle 400 and the concave base 110 or the convex base 120, to prevent the baffle 400 from slipping out of the first slot 115 or the second slot 125 under strong pulling, and to improve the reliability of the first slot 115 and the second slot 125 in limiting the baffle 400. During the assembly process of the sandblasting fixture 20, after the annular cover plate 300 is fixedly connected to the sandblasting base 100 and the positioning frame 200, the block 420 of the baffle bar 400 is embedded in the first slot 115 or the second slot 125, and the baffle bar 400 is moved so that the baffle bar 400 slides to the position of the skirt portion 102 on the UTG glass sheet that is not blocked by the annular cover plate 300 and the limit screw 500 is locked. This can achieve the fixation of the baffle bar 400 on the sandblasting base 100 to avoid the baffle bar 400 from moving relative to the sandblasting base 100 when subjected to horizontal force, thereby causing the edge of the UTG glass sheet to be directly impacted by sand particles and break into pieces.

[0077] It should be noted that, in this embodiment, by setting the baffle 400 on the sandblasting base 100, the sandblasting requirements of UTG glass of different sizes can be met by the customer, and the sandblasting fixture can be scrapped due to the change in the size of the sandblasted UTG glass, thereby reducing the development cycle and saving costs. In other words, when the size of the glass sheet to be sandblasted is smaller than the size of the sandblasting area, the sandblasting fixture can still be used to clamp the glass sheet, and the baffle 400 can be used to block the skirt portion 102 of the glass sheet located in the sandblasting area to prevent the edge of the glass sheet from being damaged by the impact of sand particles; when the sandblasting fixture 20 includes more than one baffle 400, the appropriate number of baffles 400 can be selected according to the size of the skirt portion of the glass to be sandblasted, and the position can be adjusted to ensure that the baffle 400 effectively blocks the skirt portion of the glass sheet. In addition, in the present solution, the weight of the sandblasting fixture 20 is greater than that of the traditional one-piece sandblasting base 100, which can avoid the undesirable phenomenon of uneven sandblasting of the product due to the inconsistent running speed of the sandblasting base 100 on the sandblasting machine slide rail under the action of non-vertical force when the sandblasting base 100 is insufficient in weight.

[0078] In the sandblasting operation of the UTG glass sheet, the UTG glass sheet is clamped into the sandblasting fixture 20 and sent to the sandblasting equipment, and the sandblasting parameters of the sandblasting equipment are set, wherein the sandblasting pressure is 0.3-0.35MPa, the distance between the nozzle and the substrate (UTG glass sheet) is 215-235mm, and the angle between the nozzle and the substrate is 88-92°; the transmission rate of the sandblasting fixture 20 on the sandblasting equipment is 0.15-0.25m / mins; white corundum abrasive is used for sandblasting, the sand particle diameter D50 is 19-21um, the sand-water ratio is 1:3, and the sand-water stirring frequency is 40Hz, and then the UTG glass sheet is started to be sandblasted.

[0079] S3. Smooth the UTG glass sheet to eliminate the bending problem of the sandblasting surface (user surface) of the UTG glass sheet caused by the inability to release the stress of the sandblasting surface during the sandblasting process, so as to facilitate the production and processing of the UTG glass sheet in subsequent processes and eliminate the impact on the yield of subsequent processes such as glass sheet shape cutting.

[0080] Step S3 includes:

[0081] S31, remove the protective oil on the system surface of the UTG glass sheet to prevent the protective oil from affecting the subsequent processes. When the protective oil is removed, place the glass sheet in a NaOH solution with a mass fraction of 5-8% and a temperature of 80-90°C, and continue to remove the protective ink layer on the system surface of the glass sheet for 8-12 minutes.

[0082] S32, etching the UTG glass sheet with an alkaline etching solution to smooth the UTG glass sheet. Specifically, first use an electronic scale to weigh 45 kg of water, then add 5 kg of NaG and 50 kg of NaOH in batches, stirring while adding until NaG and NaOH are completely dissolved, thereby preparing a mixed solution with a mass fraction of 50% NaOH and a mass fraction of 5% NaG to obtain an alkaline etching solution, then place the glass sheet in the alkaline etching solution, and chemically etch the glass sheet at a temperature of 115-125°C, and the etching removal amount is 0.005 mm thinning of a single side of the UTG glass sheet.

[0083] S4, cutting off the skirt portion 102 of the smoothed UTG glass sheet, and performing secondary thinning on the UTG glass sheet.

[0084] In this embodiment, by cutting off the skirt portion 102 of the smoothed UTG glass sheet, while preventing the UTG glass sheet from being directly sprayed to its edge by white corundum sand, causing the glass sheet to break, the shelf mark produced when the glass sheet is smoothed can also be removed to obtain the product size required by the customer (the length and width of the glass sheet after cutting off the skirt portion 102 are both 4.028-4.032mm larger than the length and width of the final product, and the size of this part needs to be consistent with the size reserved for sandblasting. The excess size will be removed in the subsequent process of lamination chamfering, CNC, surface etching, chamfer etching and back polishing). Specifically, laser cutting is used to remove the skirt portion 102 of the UTG glass sheet, and the cutting equipment is a laser cutting machine with a laser wavelength of 1030nm, a maximum power of 100W, a laser cutting speed of 150mm / s, a laser cutting frequency of 30000Hz, a duty cycle of 80%, and a dot pitch of 5μm. The purpose of secondary thinning of the UTG glass sheet is to remove the micro cracks on the sandblasted surface of the UTG glass sheet, enhance the strength and toughness of the UTG glass sheet after sandblasting, and further thin the UTG glass sheet to make it have good bending performance. During the secondary chemical thinning, first use an electronic scale to weigh 45Kg of water, then add 5Kg of NaG and 50Kg of NaOH in batches, stirring while adding until NaG and NaOH are completely dissolved, thereby preparing a mixed solution with a mass fraction of 50% NaOH and a mass fraction of 5% NaG to obtain an etching solution, and then place the glass sheet in the etching solution, and chemically thin the glass sheet at a temperature of 115-125°C, and the etching removal amount is 14-16μm thinning of the single side of the UTG glass sheet.

[0085] It should be noted that the thickness of the UTG glass sheet to be sandblasted designed in this scheme is 70-80μm (75μm in this embodiment). This is because when the thickness of the sandblasted UTG sample is less than 70μm, the proportion of sandblasting fractures will increase significantly. The total removal of the sandblasted surface smoothing and chemical thinning is 16.5-18.5μm. This is because when the sandblasted surface removal is less than 15μm, the microcracks on the sandblasted surface are not fully removed, and the strength and toughness of the UTG sandblasted sample cannot meet customer needs; and when the sandblasted surface removal is greater than 20μm, the sandblasted surface depth is insufficient and cannot meet the customer's required optics and roughness of the sandblasted surface. After smoothing and chemical thinning, the total thickness of the UTG glass sheet is 39-41μm, which can also meet the thickness requirements of the back cover of the folding screen electronic device required by customers. During the chemical thinning process, the glass in contact with the chemical thinning fixture produces shelf marks due to the inconsistent etching speed with other parts, which can be removed in the subsequent lamination chamfering process.

[0086] S5, stacking the UTG glass sheets after the secondary thinning to obtain a glass laminate (the structure of the glass laminate is as follows Figure 8 shown).

[0087] Step S5 includes:

[0088] S51 . Apply glue between the stacked substrate 30 and the UTG glass sheet or between two UTG glass sheets 10 to form a glue-sheet combination.

[0089] Step S51 further includes:

[0090] S511, ultrasonic cleaning: ultrasonic cleaning is used to remove the dirt and grease remaining on the surface of the UTG glass sheet during the chemical thinning process. Specifically, the surfaces of the substrate 30 and the UTG glass sheet to be bonded are cleaned and kept dry to make the surfaces free of grease, and then the bonding surfaces on both sides of the glass sheet are plasma cleaned.

[0091] S512, glue path map design: The glue path map is designed based on the size of the product dispensing area and the glue thickness, calculate the volume of the cured glue, and then calculate the glue solid content (non-volatile content) according to the following formula:

[0092] X=(V1 / V)·100

[0093] Wherein, X is the content of non-volatile matter (in %), V1 is the volume of the glue after curing, and V is the volume of the glue before curing.

[0094] Calculate the glue volume according to the following formula:

[0095] V=LxWxH

[0096] Among them, L is the length of the glue, which is determined by the dispensing area; W is the width of the glue, which is determined by the diameter of the dispensing needle; H is the height of the glue, which is determined by the dispensing speed; V is the volume of the glue before curing. According to the above calculations, combined with the outline of the sample dispensing area, the dispensing circuit diagram can be designed.

[0097] S513, fix the substrate 30 on the glue dispensing fixture, and dispense glue once on the edge of the hole (if there is a hole) of the bonding surface (upper surface) of the substrate 30 and around the glass to form a dam glue. The dam glue is 0.6-0.8mm away from the edge of the substrate 30, and then pre-cure the dam glue to achieve the shaping of the dam glue. The light intensity of the pre-curing is 750-850mW / cm 2 , the pre-curing time is 11-13s. In this solution, the purpose of applying dam glue on the substrate 30 and the glass sheet is to prevent the glue from overflowing from the substrate 30 or around the glass, thereby causing glue shortage.

[0098] S514, perform secondary glue dispensing in the area surrounded by the dam glue of the substrate 30 to form a filling glue, the amount of the filling glue is greater than the amount of glue required for the UTG glass sheet to be attached, and the excess filling glue overflows from the periphery of the glass sheet and the edge of the hole (if there is a hole) when the UTG glass sheet is attached. Attach the bonding surface of the UTG glass sheet to the corresponding position of the substrate 30, and then apply a downward pressing force to complete the bonding of the single UTG glass sheet and the substrate 30.

[0099] S52, using UV light (ultraviolet light) to irradiate the glue-board combination to solidify the glue to form a glue layer 40.

[0100] In this embodiment, the UTG glass sheets are stacked by UV light in order to cure the glue quickly, so as to shape the glue-board combination and prevent the glass sheets from shifting sideways during the subsequent stacking process. During UV light curing, ultraviolet light with a wavelength of 365nm is used to pre-cure the stacked UTG glass sheets for 6s and then final cure for 40s. The energy during curing is 1500-2000mj / cm 2 .

[0101] S53, baking the glue-board composition after the glue layer 40 is cured to remove small molecules and water generated by UV glue curing, the baking temperature is 80° C., and the baking time is 60 minutes.

[0102] S54, repeat steps S51-S53 until a glass laminate consisting of two substrates 30 arranged opposite to each other and a plurality of UTG glass sheets stacked between the two substrates 30 is formed. When the bottom UTG glass sheet is bonded to the substrate 30, each UTG glass sheet is stacked and bonded on the glass sheet one by one in sequence, and a glue layer 40 is provided on the upper and lower surfaces of each glass sheet. When the stacking height of the glass sheets reaches a preset value, another substrate 30 is attached to the upper surface of the topmost glass sheet, and the glue layer 40 is cured and baked. In this embodiment, the thickness of the substrate 30 is 0.405 mm, the thickness of a single layer of glue is 0.02 mm, and 10 layers of UTG glass sheets are stacked and separated by the glue layer between the two substrates 30. It should be noted that due to the 0-1.5mm deviation in the lamination process, the length and width design of the laminated glass is 4.028-4.032mm larger than the length and width of the CNC-processed glass laminate edge chamfer. The deviated part will be cut off during the CNC-processed glass laminate edge chamfering process.

[0103] S6. Use CNC to process the edge chamfer of the glass laminate so as to roughly process the shape of the glass laminate into the shape required by the customer, and polish the body of the glass laminate to form the 3D chamfer required by the customer. When processing the edge chamfer of the glass laminate, first perform rough cutting and then fine cutting. The spindle speed during rough cutting and fine cutting is 28000-32000rpm, the rough cutting grinding wheel uses a grinding wheel with a grit number of 400#, the rough cutting feed speed is 80mm / min, and the fine cutting grinding wheel uses a grinding wheel with a grit number of 800#, and the fine cutting feed speed is 130mm / min. When polishing the body of the glass laminate, use a pig hair brush to polish the body of the glass laminate. The length of the pig hair brush is 15-30mm. The speed when polishing the long side of the glass sheet is 1750-1850rpm, and the speed when polishing the short side of the glass sheet is 400-500rpm. After the body polishing is completed, ultrasonic cleaning is used to remove stains and grease remaining on the glass surface.

[0104] S7. Split the polished glass laminate into several UTG glass sheets, double-side protect and etch the edge chamfers of the UTG glass sheets to obtain finished products.

[0105] Step S7 includes:

[0106] S71, debonding the glass laminate so that the glass laminate is split into several UTG glass sheets, so that the glass sheets can be processed one by one later. In step S71, the glass laminate is placed in hot water for debonding. Specifically, the glass laminate is placed in deionized water at 75-85°C and soaked for 28-32 minutes to soften the glue and fall off the surface of the glass sheet.

[0107] S72. Attach protective film on both sides of the UTG glass sheet.

[0108] It should be noted that the protective film used in this embodiment is a commercially available UV anti-viscosity alkali-resistant protective film. For example, the UV anti-viscosity protective film model HSD-206F produced by Dongguan Hongshengda New Materials Co., Ltd. is selected. Other brands or models of UV anti-viscosity alkali-resistant protective films can also be selected. The thickness of the UV anti-viscosity alkali-resistant protective film is 50μm. The film-pasting requirements are that when the film material and the fixture are at room temperature, the UV anti-viscosity alkali-resistant protective film is attached to the surface of the UTG glass sheet using 55-65KPa compressed air. The pre-forming air pressure during film-pasting is 15-25KPa, the pre-forming delay is 1s, and the compressed air flow valve is 25-35%. By attaching the protective film on both sides of the UTG glass sheet, it is possible to avoid affecting the rest of the glass sheet when the edge of the alkaline-etched glass sheet is chamfered.

[0109] S73. Etch the edge chamfer of the UTG glass sheet using an alkaline etching solution.

[0110] Specifically, 45 kg of water is first weighed using an electronic scale, and then 5 kg of NaG and 50 kg of NaOH are added in batches in sequence, stirring while adding until NaG and NaOH are completely dissolved, thereby preparing a mixed solution with a mass fraction of 50% NaOH and a mass fraction of 5% NaG to obtain an etching solution, and then the film-attached glass sheet is placed in the etching solution, and the glass sheet is chemically etched at a temperature of 115-125° C., the single-side removal amount of the glass sheet is 0.01 mm, and the etching time is 60 minutes, so that the glass sheet is protected on both sides, and the exposed glass sheet body is etched with NaOH by the alkaline etching solution to form an edge chamfer.

[0111] S74, remove the protective film on the surface of the UTG glass sheet. After the chemical etching is completed, the protective film on the surface of the UTG glass sheet is removed by UV light viscosity reduction. Specifically, the UV light viscosity reduction condition is to use an LED light source with a wavelength of 365nm to irradiate the glass sheet, and the light energy is 600-1000mj / m 2 , the irradiation time is 180s.

[0112] After step S74, the following steps are also included:

[0113] S75. Chemically strengthen the UTG glass sheet to harden the UTG glass sheet. Specifically, the glass sheet is preheated continuously at 380-400°C for 59-61 minutes, then 100% solid KNO3 is added to the hardening furnace, the mass W1 of the added KNO3 is calculated, the temperature is raised to 409-411°C until the KNO3 is completely melted, and then 100% H2SiO3 is added, the mass W of H2SiO3 = W1*(0.5 / 99.5), and the hardening is continued at 409-411°C for 29-31 minutes (wherein the hardening suspension time of the glass sheet is 1 minute) to improve the hardness of the glass sheet.

[0114] S76. Place the strengthened UTG glass sheet in an alkaline etching solution for re-polishing. After re-polishing, the surface roughness Sa of the UTG glass sheet is less than 1nm. In this scheme, by re-polishing the strengthened glass sheet, the concave and convex points formed on the glass surface during the strengthening process can be removed to reduce the surface roughness of the glass sheet. During re-polishing, first use an electronic scale to weigh 45Kg of water, and then add 5Kg of NaG and 50Kg of NaOH in batches, stirring while adding until NaG and NaOH are completely dissolved, thereby configuring a mixed solution with a mass fraction of 50% NaOH and a mass fraction of 5% NaG to obtain an etching solution, and then place the film-attached glass sheet in the etching solution, and chemically etch the glass sheet at a temperature of 115-125°C. When re-polishing the UTG glass sheet, a very small thickness will be removed, and the thickness removal amount of the re-polishing can be controlled to be consistent with the thickness increase of the UTG glass strengthening process. Preferably, the single-sided removal amount of the glass sheet is 0.004-0.006mm.

[0115] In the present invention, in order to improve the sandblasting and chamfering quality of the UTG glass sheet, a large number of hypotheses are proposed for the current problems existing in the back cover of the folding screen electronic device, and the results are verified through repeated adjustments, as shown in the following table:

[0116]

[0117]

[0118] The back cover processing technology of the folding screen electronic device of the present invention is implemented. The skirt portion 102 of the UTG glass sheet is shielded by the sandblasting fixture 20, and the skirt portion 102 is removed in the subsequent operation. While sandblasting the surface of the UTG glass sheet, improving the anti-slip performance of the glass sheet, reducing the risk of glass sheet wear and scratching, and extending the service life of the product, the problem of glass sheet breakage caused by the contact between sandblasting sand particles and the edge of the glass sheet can be avoided. The removal of the skirt portion 102 can also reduce the shelf mark produced after the product is smoothed, and the defective rate of product sandblasting can be reduced; by chamfering and polishing the UTG glass sheets after stacking, the burrs remaining in the CNC processing of the UTG glass sheets can be removed while ensuring that the UTG glass sheets are not broken, thereby ensuring the strength of the UTG glass sheets; by double-sided protection and etching the edge chamfering of the polished UTG glass sheets, the chamfering of UTG glass with a thickness of less than 40μm can be met, while improving the strength and toughness of the UTG glass sheets, the yield rate of chamfering processing is significantly improved.

[0119] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0120] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A folding screen electronic device back cover processing technology, characterized in that: The following steps are involved: S1, cutting and thinning the glass once to obtain a UTG glass sheet to be sandblasted, wherein the UTG glass sheet comprises a portion to be sandblasted and a skirt portion surrounding the portion to be sandblasted; S2, placing the UTG glass sheet into a sandblasting fixture, exposing the portion to be sandblasted to the sandblasting operation area of ​​the sandblasting equipment, and allowing the sandblasting fixture to cover the skirt portion, and sandblasting the UTG glass sheet; S3, smooth the UTG glass sheet; S4, cutting off the skirt portion of the smoothed UTG glass sheet, and performing secondary thinning on the UTG glass sheet; S5, laminating the UTG glass sheets after the second thinning to obtain a glass laminate; S6, CNC machine the edge chamfers of the glass laminate and polish the body of the glass laminate; S7. Split the polished glass laminate into several UTG glass sheets, double-side protect and etch the edge chamfers of the UTG glass sheets to obtain finished products.

2. The folding screen electronic device back cover processing technology according to claim 1 is characterized in that: Step S1 includes: S11, apply protective oil on both sides of the glass material; S12, cutting and chamfering the glass material to obtain a rectangular glass sheet; S13, polishing the glass sheet and removing the protective oil on the surface of the glass sheet; S14, placing the glass sheet in an etching solution and thinning it to 0.07-0.08 mm to obtain a UTG glass sheet; S15. Apply protective oil to the system surface of the UTG glass sheet.

3. The folding screen electronic device back cover processing technology according to claim 1 is characterized in that: The sandblasting fixture comprises: A sandblasting base, the sandblasting base comprising a concave base and a convex base which are arranged opposite to each other and snap-fitted, the upper surface of the concave base being provided with a first groove, a side surface of the concave base adjacent to the convex base being provided with a mounting notch, the first groove penetrating the concave base at the side surface where the mounting notch is located; the upper surface of the convex base being provided with a second groove, a side surface of the convex base adjacent to the concave base being provided with a mounting protrusion snap-fitted with the mounting notch, the second groove penetrating the convex base at the side surface where the mounting protrusion is located; A positioning frame, the positioning frame comprising a first U-shaped frame embedded in a first groove and fixedly connected to the concave base, and a second U-shaped frame embedded in a second groove and fixedly connected to the convex base, the upper surface of the first U-shaped frame is higher than the upper surface of the concave base, the upper surface of the second U-shaped frame is higher than the upper surface of the convex base, and the first U-shaped frame and the second U-shaped frame together enclose a limiting area for accommodating the UTG glass sheet, and the height of the limiting area is less than or equal to the thickness of the UTG glass sheet; and An annular cover plate is pressed and fixed on the upper surfaces of the first U-shaped frame and the second U-shaped frame, and the annular cover plate forms a sandblasting shielding area corresponding to the skirt portion of the UTG glass sheet above the limiting area, and the inner ring area of ​​the annular cover plate forms a sandblasting area corresponding to the portion to be sandblasted of the UTG glass sheet.

4. The folding screen electronic device back cover processing process according to claim 3 is characterized in that: A plurality of first positioning holes and a plurality of first sand leakage holes are provided in the first groove, and a plurality of second positioning holes and a plurality of second sand leakage holes are provided in the second groove; a plurality of third positioning holes corresponding to each first positioning hole and a plurality of first sand leakage gaps corresponding to each first sand leakage hole are provided on the first U-shaped frame, a plurality of fourth positioning holes corresponding to each second positioning hole and a plurality of second sand leakage gaps corresponding to each second sand leakage hole are provided on the second U-shaped frame; a plurality of fifth positioning holes corresponding to each third positioning hole and a fourth positioning hole are provided on the annular cover plate; the sandblasting base also includes a plurality of first mounting screws which are sequentially connected with the fifth positioning hole, the third positioning hole and the first positioning hole to connect the annular cover plate, the first U-shaped frame and the concave base, and a plurality of second mounting screws which are sequentially connected with the fifth positioning hole, the fourth positioning hole and the second positioning hole to connect the annular cover plate, the second U-shaped frame and the convex base.

5. The folding screen electronic device back cover processing technology according to claim 3 is characterized in that: The sandblasting fixture also includes at least one baffle bar for shielding the skirt portion of the UTG glass sheet located in the sandblasting area, the baffle bar includes a horizontal bar straddled on a concave base or a convex base, and two clamping blocks arranged oppositely and fixed at both ends of the horizontal bar, the concave base is provided with two first clamping grooves arranged oppositely on the outer side of the first groove, and the convex base is provided with two second clamping grooves arranged oppositely on the outer side of the second groove; the two clamping blocks of the baffle bar are embedded in the two first clamping grooves one by one and are fixedly connected to the annular cover plate by a limit screw passing through the annular cover plate, or the two clamping blocks of the baffle bar are embedded in the two second clamping grooves one by one and are fixedly connected to the annular cover plate by a limit screw passing through the annular cover plate.

6. The folding screen electronic device back cover processing technology according to claim 2, characterized in that: Step S3 includes: S31, remove the protective oil on the surface of the UTG glass sheet system; S32. Etch the UTG glass sheet with an alkaline etching solution to smooth the UTG glass sheet.

7. The folding screen electronic device back cover processing technology according to claim 1, characterized in that: Step S5 includes: S51, applying glue between the stacked substrate and the UTG glass sheet or between two UTG glass sheets to form a glue-board composition; S52, irradiating the glue-board composition with UV light to cure the glue to form a glue layer; S53, baking the glue-board composition after the glue layer is cured; S54, repeating steps S51-S53 until a glass laminate consisting of two substrates disposed opposite to each other and a plurality of UTG glass sheets stacked between the two substrates is formed.

8. The folding screen electronic device back cover processing technology according to claim 1, characterized in that: Step S7 includes: S71, debonding the glass laminate to separate the glass laminate into a plurality of UTG glass sheets; S72, attach protective film on both sides of the UTG glass sheet; S73, etching the edge chamfer of the UTG glass sheet using an alkaline etching solution; S74. Remove the protective film on the surface of the UTG glass sheet.

9. The folding screen electronic device back cover processing process according to claim 8, characterized in that: In step S71, the glass laminate is placed in hot water for debonding.

10. The folding screen electronic device back cover processing technology according to claim 8, characterized in that: After step S74, the following steps are also included: S75, chemically strengthening the UTG glass sheet to harden the UTG glass sheet; S76, placing the strengthened UTG glass sheet in an alkaline etching solution for polishing. After polishing, the surface roughness Sa of the UTG glass sheet is less than 1 nm.

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