Processing technology for front cover of folding screen electronic equipment

Abstract

A folding screen electronic equipment front cover processing technology comprises the steps that a glass sheet is cut to obtain a glass sheet, the glass sheet is provided with a user face and a system face, and the system face is provided with a to-be-slotted area and a non-slotted area; a grinding machine thinning clamp is prepared, a vacuum air channel is formed in the grinding machine thinning clamp, the upper surface of the grinding machine thinning clamp is provided with a first adsorption area corresponding to the to-be-grooved area and provided with a plurality of adsorption holes communicating with the vacuum air channel and a second adsorption area corresponding to the non-grooved area and provided with an air groove communicating with the vacuum air channel, and the hole diameter of the adsorption holes is smaller than or equal to 2 mm; the air grooves are wider than the adsorption holes; fixing a grinding machine thinning clamp and clamping the glass sheet; mechanically thinning an area to be slotted on the glass sheet by adopting a grinding wheel; performing double-sided thinning on the mechanically thinned glass sheet by using NaOH; carrying out PVD (Physical Vapor Deposition) coating and primary hardening on the bending area of the glass sheet; and after the bent area is deplated, carrying out secondary hardening on the glass sheet to obtain the front cover of the folding screen electronic equipment.

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 front cover processing technology, which is used to achieve grinder grooving and chemical thinning of the front cover of the folding screen electronic device. Background Art

[0002] Ultra-thin glass (UTG) is glass with a thickness of 0.1-1.1mm. It has certain advantages in folding, bending, and curling, and is therefore widely used in folding screens of electronic devices to meet the 360° bending or twisting of the folding screen. Ultra-thin glass used as folding screens is mainly made by thinning the folding area (bending part) on the glass sheet to meet the needs of glass folding (rather than thinning the glass overall). For the thinned glass sheet, the light transmittance and flexibility of the thinned part are improved, and its weight is also reduced. However, as the thickness of the thinned area decreases, the mechanical strength of the glass decreases, and the thinned area of ​​the glass sheet is prone to breakage. Any impurities or microcracks during the processing will have a serious negative impact on the thinned area of ​​the glass. The industry mainly uses mechanical thinning to locally thin the glass sheet. During the mechanical thinning process, the glass sheet needs to be positioned and clamped to ensure the consistency of the thinned area. However, the industry currently mainly positions glass sheets through negative pressure adsorption and / or clamp positioning. As the glass sheets become thinner, the thinned areas on the glass sheets are extremely susceptible to damage due to impact or pressure, which in turn causes an increase in product breakage and defective rates, insufficient ultra-thin glass production efficiency, and increased ultra-thin glass processing costs. Summary of the invention

[0003] Based on this, it is necessary to provide a front cover processing technology for folding screen electronic devices with low breakage rate, high product yield and production efficiency, and low processing cost to address the above-mentioned shortcomings.

[0004] A folding screen electronic device front cover processing process, used to achieve thinning of the bending area of ​​the front cover of the folding screen electronic device, comprising the following steps:

[0005] S1, cutting a glass sheet to obtain a glass sheet to be processed, wherein the glass sheet has a user surface facing a user side when in use and a system surface facing the inside of the electronic device, and the system surface has a grooved area for forming a bending area and a non-grooved area located beside the grooved area;

[0006] S2, prepare a grinding machine thinning fixture, wherein a vacuum air channel for communicating with an external vacuum device is provided in the grinding machine thinning fixture, an adsorption platform is formed on the upper surface of the grinding machine thinning fixture, a first adsorption area corresponding to the area to be grooved and a second adsorption area corresponding to the non-grooving area are provided on the adsorption platform, a plurality of adsorption holes connected to the vacuum air channel are provided at the first adsorption area, an air groove connected to the vacuum air channel is provided at the second adsorption area, the aperture of the adsorption hole is less than or equal to 2 mm, the width of the air groove is greater than the aperture of the adsorption hole, and the total amount of air intake in the first adsorption area per unit time is less than the total amount of air intake in the second adsorption area;

[0007] S3, fixing the grinding machine thinning fixture on the grinding machine table, and clamping the glass sheet on the grinding machine thinning fixture, so that the user surface of the glass sheet is in contact with the adsorption platform, the area to be grooved of the glass sheet corresponds to the first adsorption area, and the non-grooved area of ​​the glass sheet corresponds to the second adsorption area;

[0008] S4, mechanically thinning the area to be grooved on the glass sheet using a grinding wheel on a grinder;

[0009] S5, using NaOH to perform double-sided thinning on the mechanically thinned glass sheet;

[0010] S6. Perform PVD coating on the bending area on the glass sheet, and harden the coated glass sheet once; after de-coating the bending area, harden the glass sheet a second time to obtain a front cover of a folding screen electronic device.

[0011] In one embodiment, after mechanical thinning, the thickness of the bending area is 0.095-0.115 mm; after double-sided thinning, the thickness of the bending area is 0.03-0.05 mm.

[0012] In one embodiment, the grinding wheel includes a wheel body, a through hole for passing the grinder motor shaft is opened in the middle of the wheel body, the annular side surface of the wheel body forms an annular grinding surface, and the two opposite side surfaces of the wheel body are respectively raised to form two annular steps coaxial with the through hole, the outer diameter of the annular step is smaller than the diameter of the annular grinding surface, and an arc-shaped transition portion is provided between the annular step and the annular grinding surface.

[0013] In one embodiment, in step S6, after the glass sheet is hardened for the second time, glue is applied to the bending area of ​​the system surface of the glass sheet to form a glue layer, and the thickness of the glue layer is the height difference between the grooved area and the non-grooved area.

[0014] In one of the embodiments, the surface roughness Ra of the upper surface of the adsorption platform is 0.003 mm, and the flatness of the glass sheet after being attached to the adsorption platform is less than 0.01 mm.

[0015] In one embodiment, the upper surface of the grinding machine thinning fixture is provided with a plurality of limit blocks spaced along the edge of the adsorption platform and arranged along a U-shaped path, the upper surface of the limit blocks is higher than the upper surface of the adsorption platform, and gaps are formed between adjacent limit blocks.

[0016] In one embodiment, a plurality of adsorption holes are arranged in a square matrix in the first adsorption zone, and the row spacing between the adsorption holes in the first adsorption zone is 5 mm, and the column spacing between the adsorption holes is 6.3 mm.

[0017] In one of the embodiments, a hollow groove is formed on the lower surface of the grinding machine thinning fixture at a position corresponding to the first adsorption area, and a plurality of air guide holes connected to the vacuum air duct are formed on the top surface of the hollow groove, and each air guide hole is connected to two adjacent adsorption holes on the first adsorption area, and a shielding portion for partially shielding the adsorption hole is formed between the two adjacent air guide holes.

[0018] In one of the embodiments, a guide hole communicating with the vacuum air passage is opened in the second adsorption area on the adsorption platform, and the guide hole is correspondingly communicated with the middle part of the air groove.

[0019] In one embodiment, the air groove includes a plurality of annular guide grooves arranged in a circle around the guide hole as the center, each annular guide groove is connected in sequence and connected to the guide hole, and the annular guide grooves are in a square ring structure or a circular ring structure.

[0020] In the process of processing the front cover of a folding screen electronic device of the present invention, while positioning and clamping the glass sheet to be thinned by vacuum adsorption, a first adsorption area and a second adsorption area corresponding to the area to be grooved and the non-grooved area of ​​the glass sheet are respectively arranged on the adsorption platform of the thinning fixture of the grinder, adsorption holes with an aperture less than or equal to 2 mm are opened on the first adsorption area, and an air groove with a width greater than the aperture of the adsorption hole is opened on the second adsorption area, and the total amount of air intake in the first adsorption area per unit time is made smaller than the total amount of air intake in the second adsorption area. This design can not only firmly adsorb the glass sheet to be thinned by the negative pressure generated by the compressor to prevent the glass sheet from shifting during the processing; it also reduces the area to be grooved. The adsorption force can avoid the glass to be thinned by the grinder after thinning due to excessive local adsorption force in the area to be grooved. It can also play a buffering role when the air pressure fluctuates, avoiding the problem of glass fragmentation caused by excessive fluctuations in the adsorption force in the area to be grooved, reducing the glass fragmentation rate and defective rate, and improving the production efficiency of ultra-thin glass. In addition, the combination of grinder thinning and NaOH chemical thinning can avoid the problem of increased breakage ratio caused by grinder grooving and thinning to a thickness of less than 0.08mm in the bending area of ​​the glass, and can also avoid the problem of excessive thinning and removal and increased cost caused by etching the entire glass with the NaOH system alone, thereby reducing the processing cost of ultra-thin glass. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structure of a front cover of a folding screen electronic device in one embodiment of the present invention;

[0022] Figure 2 A schematic diagram of the structure of a grinding machine thinning fixture in one embodiment of the present invention;

[0023] Figure 3 A schematic cross-sectional structure diagram of a grinding machine thinning fixture from one perspective in one embodiment of the present invention;

[0024] Figure 4 A schematic cross-sectional structure diagram of a grinding machine thinning fixture from another perspective in one embodiment of the present invention;

[0025] Figure 5 A schematic structural diagram of a grinding machine thinning fixture in another embodiment of the present invention;

[0026] Figure 6 A schematic diagram of the structure of a grinding wheel in one embodiment of the present invention;

[0027] Figure 7 is a schematic diagram of the cross-sectional structure of a grinding wheel in one embodiment of the present invention;

[0028] Figure 8 A schematic diagram of dispensing glue on a glass sheet in one embodiment of the present invention;

[0029] Fig. 9 A schematic diagram of an explosion structure when a glass sheet is mechanically thinned in one embodiment of the present invention;

[0030] Fig.10 This is a flow chart of a front cover processing process for a folding screen electronic device in one embodiment of the present invention. DETAILED DESCRIPTION

[0031] 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.

[0032] The present invention discloses a method for thinning the bending area of ​​the front cover of a folding screen electronic device by combining grinder grooving and NaOH system etching to improve the yield rate of thinning in the bending area of ​​the product and realize the bending function of the thinning area of ​​the folding screen glass. After mechanically thinning the bending area on the glass sheet, the glass sheet is thinned as a whole by chemical etching, and then the mechanically thinned area on the glass sheet is protected by PVD coating, hardened once, and then after stripping, the entire glass sheet is hardened twice to improve the surface quality and mechanical strength of the folding screen glass sheet. In this embodiment, the advantages of mechanically thinning the glass sheet by a grinder are: 1) The grinding machine processing can achieve high-precision processing, and the thickness tolerance can reach less than ±0.01mm, which can meet the thickness requirements of the thinning process of the bending part of the folding screen glass; 2) The grinding machine processing is not limited by the material and shape of the workpiece, and has a wide range of applicability, and can meet the grinding machine thinning of the bending area of ​​various glass folding screens including Corning's 7418 model; 3) The process is simple and the price is low.

[0033] For details, please combine Figure 1-10 The front cover processing technology of the folding screen electronic device of this embodiment includes the following steps:

[0034] S1. Cutting the original glass sheet to obtain a glass sheet 10 to be processed, wherein the glass sheet has a user surface facing the user side when in use and a system surface facing the inside of the electronic device, and the system surface has a grooved area 101 for forming a bending area and a non-grooved area 102 located next to the grooved area 101. The user surface of the glass sheet is protected by screen printing acid-resistant protective oil to avoid the user surface being scratched by hard objects during subsequent production or transportation, so as to improve the quality of the finished product.

[0035] S2. Prepare a grinding machine thinning fixture 20, which is designed as a vacuum adsorption fixture. A vacuum air passage 201 for connecting to an external vacuum device is provided in the grinding machine thinning fixture 20, and an adsorption platform 202 is formed on the upper surface of the grinding machine thinning fixture 20. A first adsorption area corresponding to the slotted area 101 and a second adsorption area corresponding to the non-slotted area 102 are provided on the adsorption platform 202. A plurality of adsorption holes 203 connected to the vacuum air passage 201 are provided at the first adsorption area, and an air groove 204 connected to the vacuum air passage 201 is provided at the second adsorption area. The aperture of the adsorption hole 203 is less than or equal to 2 mm, and the width of the air groove 204 is greater than the aperture of the adsorption hole 203, and the total amount of air intake in the first adsorption area per unit time is less than the total amount of air intake in the second adsorption area. That is to say, the area to be grooved 101 on the glass sheet is adsorbed and fixed through the adsorption hole 203 with a smaller aperture, and the non-grooved area 102 on the glass sheet is adsorbed through the air groove 204 with a larger width. Due to the different sizes of the adsorption hole and the air groove 204, the ventilation volume and ventilation rate of the two are also different, so that the adsorption force of the first adsorption area on the area to be grooved 101 on the glass sheet is smaller than the adsorption force of the second adsorption area on the non-grooved area 102 on the glass sheet. In this way, the glass sheet can be firmly adsorbed by the second adsorption area to prevent the glass sheet from shifting due to friction with the grinding wheel during the grooving and thinning process of the grinder, and the glass thinned by the grinder can be prevented from being broken due to excessive local adsorption force at the grooved part of the glass after the grinder thins the glass; it can also play a buffering role when the air pressure fluctuates, avoiding the problem of broken pieces in the grooved area on the glass sheet due to excessive fluctuations in the adsorption force.

[0036] In one embodiment, a plurality of adsorption holes 203 are arranged in a first adsorption zone in a square array, the row spacing between the adsorption holes 203 in the first adsorption zone is 5 mm, the column spacing between the adsorption holes 203 is 6.3 mm, the arrangement length of the adsorption holes 203 in the first adsorption zone is equal to the length of the first adsorption zone, and the arrangement width of the adsorption holes 203 in the first adsorption zone is equal to the width of the first adsorption zone. In other words, a plurality of adsorption holes 203 cover the entire first adsorption zone with a predetermined row spacing and column spacing to ensure that the area 101 to be grooved on the glass sheet can be evenly and stably adsorbed on the grinding machine thinning fixture 20, and ensure that the grooved area of ​​the finished glass sheet is stably stressed to prevent breakage.

[0037] Furthermore, a hollow groove 205 is provided on the lower surface of the grinding machine thinning fixture 20 at a position corresponding to the first adsorption area, and a plurality of air guide holes 206 connected to the vacuum air channel 201 are provided on the top surface of the hollow groove 205, and each air guide hole 206 is connected to two adjacent adsorption holes 203 on the first adsorption area, and a shielding portion for partially shielding the adsorption hole is formed between two adjacent air guide holes 206. By providing the hollow groove 205, it is convenient to conduct the air pressure in the vacuum air channel 201 to the adsorption hole 203 via the air guide hole 206, and the air pressure in the vacuum air channel 201 is gradually divided by the air guide hole and the adsorption hole to reduce the adsorption force at the first adsorption area to avoid glass overload and fragmentation. In addition, during the process of grinding and thinning the bending area of ​​the glass by the grinding wheel, when the glass to be thinned is adsorbed on the fixture, it is necessary to spray coolant on the surface of the glass to avoid glass breakage due to the increase in temperature when the grinding wheel is grinding and thinning the bending area of ​​the glass; in this process, part of the coolant entering the adsorption hole will further enter the hollow groove through the air guide hole, and be further sucked away by the vacuum pump of the compressor, thereby reducing the retention of coolant in the adsorption hole. The hollow groove provides a storage space for the coolant, which can avoid the problem of blockage of the adsorption hole caused by a large amount of coolant accumulation in the adsorption hole, thereby ensuring the stability of the adsorption force in the first adsorption area.

[0038] In this embodiment, the vacuum air duct 201 passes through two opposite sides of the grinder thinning fixture 20 and forms an air vent 207 on the side of the grinder thinning fixture 20. The air vent 207 is used to install an air pipe joint so as to connect the grinder thinning fixture 20 with an external vacuum device (such as a compressor). When the grinding machine thinning fixture 20 is fixed on the grinding machine, the grinding machine blocks the notch of the hollow groove 205. After the air vent 207 of the grinding machine thinning fixture 20 is connected to the compressor, negative pressure is formed in the vacuum air channel 201 at the corresponding first adsorption area and the second adsorption area respectively. The air above the first adsorption area enters the vacuum air channel 201 through the adsorption hole and the air guide hole 206 in sequence under the action of negative pressure, and is further transmitted to the compressor through the vacuum air channel 201 and the air vent 207, thereby forming an air flow channel. Since each air guide hole 206 is connected to two adjacent adsorption holes on the first adsorption area, and the shielding part partially shields the adsorption hole, it can also be understood that the air guide hole 206 is staggered with the adsorption hole. In this way, while the air guide hole 206 connects the adsorption hole with the vacuum air channel 201, it partially shields the adsorption hole to further reduce the aperture of the adsorption hole, thereby further reducing the impact of the first adsorption area on the product processing part, avoiding product fragmentation, and improving the product yield. In order to avoid air leakage at the hollow groove 205, in the present embodiment, a sealing rubber ring is provided at the edge of the groove of the hollow groove 205. When the grinding machine thinning fixture 20 is set on the grinding machine platform, the sealing rubber ring is deformed under the extrusion of the grinding machine platform to block the gap at the edge of the groove of the hollow groove 205, thereby avoiding air leakage at the hollow groove 205, so as to ensure the stability of the air pressure in the vacuum air duct 201 and the reliability of product adsorption.

[0039] Furthermore, the radius of the air hole 207 is 4.4 mm, the distance from the upper edge of the air hole 207 to the upper surface of the adsorption platform 202 is 14.6 mm, the distance from the lower edge of the air hole 207 to the lower surface of the grinder thinning fixture 20 is 10.6 mm, the radius of the air guide hole 206 is 2.25 mm (the aperture is 4.5 mm), the depth of the hollow groove 205 is 3 mm, the distance from the lower edge of the air hole 207 to the top surface of the hollow groove 205 is 7.6 mm, and the height of the adsorption platform 202 is 10 mm. In this embodiment, the distance from the upper edge of the vent hole 207 to the upper surface of the adsorption platform 202 is designed to be 14.6 mm, and the distance from the lower edge of the vent hole 207 to the lower surface of the grinder thinning fixture 20 is designed to be 10.6 mm, which can effectively avoid the problem of depression of the adsorption hole 203 area and the air guide hole 206 setting area (also called the hollow part) caused by the force of the grinder thinning fixture 20 during the grinder slotting process, so as to extend the service life of the grinder thinning fixture 20 and ensure the reliability of positioning the glass sheet. The height of the adsorption platform 202 is designed to be 10 mm, which provides conditions for the grinder thinning fixture 20 to be repaired due to unqualified flatness after installation, and increases the service life of the grinder thinning fixture 20. The depth of the hollow groove 205 is designed to be 3mm. The coolant in the glass grinding process can enter the hollow groove 205 through the adsorption hole 203 and the air guide hole 206, avoiding the blockage of the adsorption hole caused by the accumulation of a large amount of coolant in the adsorption hole, so as to ensure the stable adsorption of the bending part of the glass. The radius of the vent hole 207 is designed to be 4.4mm. While ensuring sufficient air supply to the grinder thinning fixture 20, it can also avoid the grinder thinning fixture 20 being deformed by force during the grinder thinning process due to the excessively large aperture of the vent hole 207 of the grinder thinning fixture 20, so as to extend the service life of the grinder thinning fixture 20.

[0040] In one embodiment, a guide hole 208 connected to the vacuum air channel 201 is provided in the second adsorption area on the adsorption platform 202, and the guide hole 208 is connected to the middle part of the air groove 204. By providing the air groove 204 in the second adsorption area, the negative pressure contact area between the non-grooved area 102 on the product and the adsorption platform 202 is increased, thereby improving the stability and reliability of the positioning of the product on the adsorption platform 202. Furthermore, the air groove 204 includes a plurality of annular guide grooves arranged in circles around the guide hole 208 as the center, and each annular guide groove is sequentially connected and connected to the guide hole 208, and the annular guide groove is a square ring structure or a circular ring structure. Preferably, the diameter of the guide hole 208 is 8 mm, and the depth of the air groove 204 is 8 mm. In this embodiment, the annular guide groove is a square ring structure, that is, the air groove 204 is a U-shaped structure, so that the non-grooved area 102 on the product is evenly stressed. Of course, in other embodiments, the air groove 204 may also be a maze structure, a mesh structure, a field structure, a Feng structure or other structures, and the projection pattern of the air groove 204 on the upper surface of the adsorption platform 202 may also be a QR code pattern, which will not be repeated here.

[0041] In addition, in the present embodiment, the grinder thinning fixture 20 is made of acrylic material. The acrylic material has the advantages of easy processing, deformation resistance, moderate strength and hardness, colorless and transparent, and light weight. It has excellent corrosion resistance under the conditions of grinder use, and can avoid defects such as surface oxidation of metal materials and the trouble of maintenance before and after use. The accuracy and surface quality of the acrylic molding surface can also meet the requirements of the grinder for grooving and thinning glass. In addition, acrylic raw materials are abundant and inexpensive, which is conducive to reducing the production cost of the grinder thinning fixture 20.

[0042] In addition, in one embodiment, please refer to Figure 5 The upper surface of the grinding machine thinning fixture 20 is provided with a plurality of limit blocks 209 arranged along the edge of the adsorption platform 202 and arranged along a U-shaped path. The upper surface of the limit blocks 209 is higher than the upper surface of the adsorption platform 202. A notch 2091 is formed between adjacent limit blocks 209. The limit blocks 209 are fixed to the upper surface of the grinding machine thinning fixture 20 by screws or pins. The plurality of limit blocks 209 and the adsorption platform together form a glass clamping area. In this way, while the limit blocks are used to limit the glass, the notches 2091 between adjacent limit blocks 209 form a sampling platform. When the glass sheet is processed, the glass can be taken out by inserting the thin sheet into the notch 2091 so that the thin sheet enters the lower part of the glass, thereby reducing the difficulty of taking out the glass.

[0043] S3. Fix the grinder thinning fixture 20 on the grinder table, and clamp the glass sheet on the grinder thinning fixture 20, so that the user surface of the glass sheet is in contact with the adsorption platform 202, the area to be grooved 101 of the glass sheet corresponds to the first adsorption area, and the non-grooved area 102 of the glass sheet corresponds to the second adsorption area.

[0044] Specifically, a screw is used to fix the screw hole of the grinder thinning fixture 20 and the screw hole of the magnetic base 40 together, and the magnetism of the base 40 is used to adsorb the base 40 and the grinder thinning fixture 20 together on the grinder fixture platform, and the vent 207 is connected to the compressor air pipe; then the glass sheet is fixed to the grinder thinning fixture 20 by vacuum adsorption, so that the to-be-grooved area 101 of the glass sheet corresponds to the first adsorption area, and the non-grooved area 102 of the glass sheet corresponds to the second adsorption area, and the grinding wheel is installed on the grinder and the height of the grinding wheel and the glass sheet is adjusted in sequence.

[0045] In this embodiment, the surface roughness Ra of the upper surface of the adsorption platform 202 is 0.003mm. By changing the surface roughness Ra of the adsorption platform 202, the positioning accuracy of the product can be improved; the flatness of the glass sheet after being attached to the adsorption platform 202 is less than 0.01mm. After the grinder thinning fixture 20 is fixed on the grinder machine, its flatness needs to be tested. If the flatness test result is >0.01mm, the fixture assembled by the grinder can be used (i.e., the surface of the fixture is ground to make the surface of the fixture flat), until the fixture assembled on the grinder operating platform has a flatness test result of <0.01mm, so as to prevent the overall flatness of the fixture from being unqualified due to the superposition of the flatness of each component after the fixture is assembled, and then the uneven thickness of the thinning area of ​​the folding screen glass or abnormal fragmentation occurs.

[0046] S4. Use the grinding wheel 30 on the grinding machine to mechanically thin the area to be grooved 101 on the glass sheet. At the same time, start the cooling liquid to spray the thinned area and clean the debris on the glass surface.

[0047] In this embodiment, the grinding wheel 30 includes a wheel body 301, a through hole 302 for passing the grinder motor shaft is opened in the middle of the wheel body 301, the annular side surface of the wheel body 301 forms an annular grinding surface 303, and the two opposite side surfaces of the wheel body 301 are respectively raised to form two annular steps 304 coaxial with the through hole 302, the outer diameter of the annular step 304 is smaller than the diameter of the annular grinding surface 303, and an arc-shaped transition portion 305 is provided between the annular step 304 and the annular grinding surface 303. It can also be understood that, in this embodiment, the grinding wheel 30 is actually a stepped structure, and a step is formed between the annular step 304 and the annular grinding surface 303. In this way, not only can the step difference formed by laser grooving and CNC grooving be avoided during the grooving process, but also the step height between the annular step 304 and the annular grinding surface 303 can be used to control the grooving removal amount of the grinding wheel 30 (i.e., the grooving depth of the bending area on the glass sheet), and the grooving depth of the glass sheet can be controlled by selecting a grinding wheel 30 with different step heights; at the same time, the annular step 304 can also repair the flare formed by the grinding wheel 30 not moving in a straight line, ensuring that the intersection line of the grooving area is a straight line. In addition, during the grooving process of the grinding wheel 30 on the glass, since the user surface of the glass sheet is silk-screened with acid-resistant protective oil, the user surface of the glass sheet can be prevented from being scratched during the grooving process of the grinder. The setting of the arc-shaped transition portion 305 between the annular step 304 and the annular grinding surface 303 ensures a smooth transition of the grooving and thinning area of ​​the grinder on the glass sheet. It should be noted that, in the present embodiment, whether the grinding wheel 30 is an electroplated grinding wheel 30 or a sintered grinding wheel 30, an 800# grinding wheel is required to reduce the depth of scratches on the surface of the glass sheet during the grooving process, and because the electric sand layer of the 800# grinding wheel is thicker, the service life of the grinding wheel 30 can be extended to reduce the cost of thinning the glass; in addition, the surface roughness Sa of the folding screen glass thinned by the 800# grinding wheel grinder is <500nm, which can meet the surface smoothness and roughness of the thinning area of ​​the folding screen glass grinder and improve the surface quality of the glass sheet.

[0048] After adjusting the height of the grinding wheel 30 and the glass sheet, turn on the grinder to grind the folding screen to-be-grooved area 101 until the thickness of the to-be-grooved area 101 (bending area) of the glass sheet to be grooved and thinned by the grinder reaches 0.095-0.115mm, then remove the glass, check the appearance, and measure the thickness of the bending area of ​​the folding screen. After the glass is mechanically thinned, the grooved area on the glass needs to be polished to reduce surface scratches on the grooved area and optimize the surface quality of the folding screen glass. Specifically, use pig hair to polish the bending area of ​​the glass to eliminate poor appearance such as the grinding wheel 30 marks produced by the thinning of the grinder; after the pig hair polishing is completed, use a carpet to polish the bending area of ​​the glass until the appearance of the bending area of ​​the glass meets the requirements of subsequent processing. After the glass sheet is polished, an alkaline deplating solution must be used to remove the acid-resistant protective oil silk-screened on the user surface of the folding screen glass sheet.

[0049] S5. Use NaOH to thin the glass sheet on both sides after mechanical thinning until the thickness of the bent part of the glass sheet meets the requirements of the folding screen glass.

[0050] Using NaOH to thin folding screen glass has the following advantages over traditional HF thinning:

[0051] 1) Uniformity: The rate at which NaOH etches and thins folding screen glass is about 3 times slower than that of HF. When using a vertical chemical treatment system, the product will not be unevenly etched due to residual chemicals dripping under the action of gravity when it is transferred from the etching tank to the clean water tank.

[0052] 2) Easy to control: Since the thickness requirement of the bending part is 0.03-0.05mm, for samples with a thickness of more than 0.08mm in the thinning area, they are classified according to the thickness of the bending area before etching and thinning in the NaOH system. Samples of different thicknesses correspond to different NaOH system etching and thinning times. Since the thinning rate of the NaOH etching system with the same concentration is 1 / 3 of the HF system etching and thinning rate, the NaOH etching and thinning system is more likely to avoid many defects such as uneven etching, product deformation and ripples that occur in the HF system etching and thinning system, making the glass thinning process easier to control.

[0053] 3) Environmental protection: The NaOH etching thinning process does not require the use of harmful organic solvents and acidic solutions and is environmentally friendly.

[0054] In addition, when HF is used for whole-surface thinning, the sample thickness is reduced from 0.2mm to 0.03-0.05mm, which is not only expensive, time-consuming, and wasteful, but also prone to fragmentation and uneven thickness. In this embodiment, for samples with a thickness greater than 0.08mm in the grooved area of ​​the grinder, after mechanical polishing to reduce surface scratches, the NaOH system is used for etching to thin the entire glass sheet to a thickness of 0.03-0.05mm at the bending part. The NaOH etching system includes 50% NaOH and 5% NaG (sodium gluconate), and the etching temperature is 115-125°C.

[0055] The chemical reaction equation is as follows: SiO 2 +2NaOH=Na 2 SiO 3 +H 2 O; SiO 3 2- +H 2 O=H 2 SiO 3 +2OH - Among them, SiO 3 2- The H generated by hydrolysis 2 SiO 3(commonly known as "water glass") coated on the surface of etched glass, affecting the etching effect; adding 5% NaG can inhibit SiO 3 2- The hydrolysis of H 2 SiO 3 Effect on etching.

[0056] Due to the use of 50% NaOH and 5% NaG (sodium gluconate), the etching temperature is 115-125°C, and the etching speed of the thinning system is significantly slower than that of HF thinning. When the etching is half of the theoretical calculation time required, chemical thinning is performed again in batches according to the measured thickness of the glass thinned by etching with the NaOH system to reduce the breakage rate of the chemically thinned glass and the defective rate of uneven etching thickness.

[0057] In one embodiment, after mechanical thinning, the thickness of the bending area is 0.095-0.115mm; after double-sided thinning, the thickness of the bending area is 0.03-0.05mm. In this way, the problem of increased cracking ratio caused by the thickness of the thinned area on the glass sheet being less than 0.08mm during the grinding process can be avoided, and the problem of increased processing cost caused by excessive thinning removal when etching the entire glass sheet by the NaOH system can be avoided. In this embodiment, the glass sheet system surface adopts a thinning method combining grinding machine grooving and NaOH system etching to make it have a bending function. The grooving depth, that is, the mechanical thinning removal, is the height of the transition part between the to-be-grooved area 101 and the grooving area on the glass sheet. It needs to determine the thickness of the incoming material according to user needs, and then subtract the ideal grinder groove retention thickness of 0.095-0.115mm. The calculated thickness removal is the grooving depth. The transition part between the to-be-grooved area 101 and the grooving area is designed as a curved surface, and its contour is adapted to the contour shape of the arc-shaped transition part 305 on the grinding wheel 30.

[0058] S6. Perform PVD coating on the bending area on the glass sheet, and harden the coated glass sheet once; after de-coating the bending area, harden the glass sheet a second time to obtain a front cover of a folding screen electronic device.

[0059] In this embodiment, since the thickness of the thinning area of ​​the folding screen glass grinder is 0.03-0.05mm, and the thickness of the non-grooving area 102 is greater than 0.05mm, the thickness of the bending area of ​​the folding screen glass is thinner than the non-grooving area. If the hardening parameters that meet the thickness of the glass bending area are used to harden the entire glass, the chemical strengthening time of the non-grooving area of ​​the folding screen glass will be too short and the strength will be low; if the hardening parameters that meet the thickness of the non-grooving area of ​​the glass are used to harden the entire glass, the chemical strengthening time of the bending area of ​​the folding screen glass will be too long and the glass will break; in addition, the uneven chemical strengthening layer on the surface of the glass will also cause the transition between the to-be-grooved area 101 and the grooved area on the glass sheet to bend. Therefore, in this embodiment, the grooved area on the glass sheet is first coated for protection, and after the non-grooving area 102 is hardened once, the entire glass is hardened after de-plating to ensure the overall strength of the glass sheet and avoid fragmentation.

[0060] Specifically, the bending area on the glass sheet is first subjected to PVD coating. In this embodiment, the PVD coating of the bending area on the glass sheet includes coating the grooved area on the system surface of the glass sheet and coating the area on the user surface of the glass sheet corresponding to the grooved area, that is, the two opposite sides of the bending part of the glass sheet are coated. Coating parameters: temperature is 88-92°C, coating material is Al2O3, and coating thickness is 45-55nm. Subsequently, the coated glass sheet is subjected to the first chemical strengthening. The first chemical strengthening conditions are: preheating time is 25-35min, preheating temperature is 270-290°C, first chemical strengthening time is 115-125min; first chemical strengthening temperature is 378-382°C; consumables are 99-100% NaNO 3 (WT%) / 0.4-0.6% H 2 SiO 3 (WT%). After the first chemical strengthening, the coating in the bending area needs to be removed. In this embodiment, an alkaline stripping solution is used to remove the coating in the bending area of ​​the glass sheet; the stripping temperature is 115-125°C, the stripping consumables are 48-52% NaOH (WT%), and the stripping time is 8-12min. After stripping, the entire glass is subjected to a second chemical strengthening. The second chemical strengthening conditions are: preheating time is 29-31min, preheating temperature is 270-290°C, second chemical strengthening time is 1-3min; second chemical strengthening temperature is 378-382°C; consumables are 99-100% NaNO 3 (WT%) / 0.4-0.6% H 2 SiO 3 (WT%). The first chemical strengthening is to chemically strengthen all parts of the glass except the coated area, and the second chemical strengthening is to coat the entire glass after stripping.

[0061] It should be noted that, in the present embodiment, in step S6, after the glass sheet is hardened for the second time, glue is also dispensed in the bending area of ​​the system surface of the glass sheet to form a glue layer 103, and the thickness of the glue layer 103 is the height difference between the grooved area 101 and the non-grooved area 102. Specifically, by dispensing glue in the bending area of ​​the system surface of the glass sheet, the thickness difference between the grooved area and the non-grooved area 102 on the system surface is filled, which improves the look and feel of the folding screen glass thinned by the grinder, and also increases the number of bending times of the folding screen glass thinned by the grinder. Preferably, in the present embodiment, the bending radius of the bending area of ​​the front cover of the folding screen electronic device is less than 1.5 mm, and the 180° bending life of the bending area is greater than 250,000 times. In addition, in the present embodiment, after the glass sheet completes the second chemical strengthening, the NaOH system is used to re-polish the glass sheet from which the PVD coating is removed.

[0062] The dispensing process includes:

[0063] 1) Before dispensing, use a micrometer to measure the thickness of the grinder-thinned area on the folding screen glass and the height T of the step formed by the non-grinder-thinned area. Combined with the length L and width W of the grinder-thinned area, calculate the volume V1 of the UV glue after curing: V1 = L*W*T;

[0064] 2) Calculate the volume V0 of the liquid glue before curing based on the volume V1 after curing: V0 = V1 / X, where X represents the content of non-volatile matter;

[0065] 3) Before dispensing glue, clean the surface of the folding screen glass to be glued, keep it dry and free of grease, and then perform plasma cleaning on the grooved area;

[0066] 4) Choose epoxy resin UV curing glue for dispensing;

[0067] 5) Use glue with a volume greater than V0 to dispense glue, and the excess glue will overflow from around the dam glue 104 (such as Figure 7 As shown), until there is no step difference between the bending area and the non-bending area;

[0068] 6) After curing, a front cover of a folding screen electronic device is obtained. The curing conditions are LED irradiation, a wavelength of 365nm, and an energy of 1500-2000mj / cm 2 , the pre-setting time is 6s and the final setting time is 40s.

[0069] It should be noted that, in order to improve the quality of the glass sheet, this embodiment also proposes a large number of assumptions for the current problems of the glass sheet and verifies the results through repeated adjustments, as shown in the following table:

[0070]

[0071] The following is a specific example to illustrate the preparation process of the glass front cover of a foldable screen electronic device.

[0072] 1) Apply protective oil

[0073] For the glass material of Corning model 7418, double-sided protective oil is screen-printed on the glass material to avoid damage to its surface in subsequent processes. The parameters are as follows: the consumables use 4500PN acid-resistant protective oil, ink thickness: 15-25um / side, surface drying: 175-185℃, lasting 3mins; final curing: 175-185℃, lasting: 30mins, and the screen printing screen uses a model 77T screen.

[0074] 2) CNC split

[0075] The large-sized glass material with double-sided protective oil printed on it is split to facilitate the subsequent production process. The splitting parameters are as follows: the feed speed is 35000-60000mm / min, the cutting wheel uses a diamond grinding wheel; the cutting depth is 0.005-0.01mm, and the cutting pressure is 1-2MPa.

[0076] 3) CNC contour and chamfering

[0077] The purpose of CNC contour and chamfering is to rough-process the shape of the cut glass to obtain the shape required by the user. The parameters are as follows: the spindle speed is 28000-32000rpm, the rough cutting feed speed is 80mm / min, the fine cutting feed speed is 130mm / min, the rough cutting grinding wheel is 400# grinding wheel, and the fine cutting grinding wheel is 800# grinding wheel.

[0078] 4) Polishing glass sheet

[0079] The purpose of polishing the glass is to remove the sharp corners or burrs produced by CNC processing of the glass to avoid scratches, breakage and other defects in subsequent processes. The equipment uses an ear polishing machine with the following parameters: the polishing brush is a pig bristle brush with a length of 15-30mm, the speed of polishing the long side is 1750-1850rpm, and the speed of polishing the short side is 400-500rpm

[0080] 5) Remove protective oil

[0081] It is mainly used to remove the protective oil on the glass sheet system surface (grinding machine groove surface) behind the polished glass sheet (when removing the oil, the protective oil will be removed from both sides of the glass sheet), otherwise it will affect the accuracy of the grinder thinning the folding screen glass. The de-plating parameters are as follows: the de-plating temperature is 80-90℃, the de-plating consumables: 5-8% NaOH (WT%), and the de-plating time is 8-12min.

[0082] 6) Screen printing protective oil on the glass surface

[0083] For the samples with double-sided protective oil removed, the glass sheet is screen-printed with protective oil on the user side to avoid damage to the surface in subsequent processes. The parameters are as follows: the consumables are 4500PN acid-resistant protective oil, ink thickness: 15-25um / side, surface drying: 175-185℃, lasting 3mins; final curing: 175-185℃, lasting 30mins, and the screen printing screen uses a 77T screen.

[0084] 7) Grinding machine slotting and thinning

[0085] The grinder grooving and thinning designed in this embodiment only thins the bent part of the folding screen glass. The incoming glass sheet has a thickness of 0.495-0.515mm (including the thickness of the user surface ink), and the removed thickness is 0.399-0.401mm. The grinder grooving thins the thickness of the bent part of the folding screen glass to 0.095-0.115mm.

[0086] Material thickness Removal thickness Grinding wheel model Slot width Speed Feed 0.405±0.01mm 0.3±0.01mm 800# 25±0.2mm 2800±50RPM 0.14-0.17mm / min

[0087] 8) 3D polishing

[0088] The system surface of the grinder-thinned sample is polished with pig hair to reduce surface scratches and optimize the system surface quality. The removal amount of the grinder-thinned area is 0.02-0.03mm, and the equipment used is Huazhongli polishing machine.

[0089] Disc pressure Consumables Polishing liquid Polishing liquid concentration Upper / lower plate speed Polishing time 75±25kg Pig hair CeO2 50=1.2±0.2um 10-15Bar 240±30RPM / 2-15RPM 2000S

[0090] 9) Remove the protective oil from the glass system surface

[0091] After 3D polishing, the protective oil on the glass surface needs to be removed, otherwise it will affect subsequent processing. The degreasing parameters are as follows: degreasing temperature is 80-90℃, de-plating consumables are 5-8% NaOH (WT%), and de-plating time is 8-12min.

[0092] 10) Carpet polishing

[0093] The samples after removing the protective oil are carpet polished to remove scratches on the surface of the folding screen glass or remove defects such as 3D polishing that is not polished through, and further optimize the surface quality of the system. The removal amount of the thinning part of the grinder is 0-0.005mm, and the equipment uses a polishing machine model Guangzhou 13.7B.

[0094] Disc pressure Consumables Whitehead grinding fluid Polishing liquid concentration Upper / lower plate speed Polishing time 80-120kg carpet CeO2 50=0.8±0.2um 15-20bar 10±5RPM / 20±5RPM 800S

[0095] 11) NaOH alkaline etching thinning

[0096] For the folding screen glass sample with a thickness of 0.06-0.08mm in the thinning area (groove area) of the fine-grinded incoming material, the NaOH system is used to etch the entire piece of glass, so that the thickness of the thinning area of ​​the glass piece on the grinder is 0.03-0.05mm (Note: the glass will expand after hardening to form an increase), and the NaOH alkaline etching parameters are as follows: the reagent is 50% NaOH + 5% NaG, the etching temperature is: 115-125℃, and the removal amount is 0.03-0.035mm / surface; the NaOH etching system adopts a vertical chemical treatment system; the etching time is 60min; quality control parameters: the thickness of the thinning area on the grinder is <0.05mm.

[0097] 12) PVD coating in thinned area

[0098] First, the thinning area of ​​the grinder is PVD coated. The coating parameters are: temperature is 88-92℃, and the coating material is Al 2 O 3 , the coating thickness is 45-55nm.

[0099] 13) First chemical strengthening

[0100] After PVD coating is completed, the first chemical strengthening is carried out. The chemical strengthening conditions are as follows: preheating time is 25-35min, preheating temperature is 270-290℃, first chemical strengthening time is 115-125min; first chemical strengthening temperature is 378-382℃; consumables are 99-100% NaNO 3 (WT%) / 0.4-0.6%H 2 SiO 3 (WT %).

[0101] 14) De-plating PVD film

[0102] After the first chemical strengthening is completed, PVD stripping is performed. The stripping temperature is 115-125°C, the stripping consumables are 48-52% NaOH (WT%), and the stripping time is 8-12 minutes. 2 O 3 It has two properties. It is calculated that 50% NaOH (WT%) can etch away 50nm thick Al within 8 minutes at 120℃. 2 O 3 PVD coating, and the main component is SiO 2 The glass material is less damaged.

[0103] 15) Second chemical strengthening

[0104] The preheating time for the second chemical strengthening is 29-31min, the preheating temperature is 270-290℃, the second chemical strengthening time is 1-3min (hardening suspension time is 1min); the second chemical strengthening temperature is 378-382℃; the consumables are 99-100% NaNO 3 (WT%) / 0.4-0.6% H 2 SiO 3 (WT %).

[0105] 16) Throwback

[0106] After the second chemical strengthening is completed, the folding screen glass after the second chemical strengthening needs to be re-polished to remove the concave and convex points formed on the glass surface during the hardening process, so that the surface roughness is reduced to Sa<1nm. The re-polishing parameters are as follows: the consumables are carpet, the polishing equipment is Guangzhou 13B polishing machine, the upper / lower plate speed is 5-15rpm / 25-35rpm; the batch number is 3PCS / batch; the plate pressure is 80-120kg, and the polishing liquid is white CeO 2 Grinding liquid, D50 = 0.6-1um, among which, the folding screen glass will have a very small thickness removed when it is returned to the polishing process, and the thickness removal amount is basically the same as the increase in the hardening of the folding screen glass.

[0107] 17) Glue Dispensing

[0108] In order to fill the gap between the thinning area of ​​the folding screen glass grinder and the ungrooved thinning area due to inconsistent thickness, glue is used to fill it. The solution is as follows:

[0109] 1) Calculate the solid colloid glue: Before dispensing, use a micrometer to measure the step difference H formed by the thickness of the grooved area of ​​the folding screen glass grinder being thinner than the ungrooved area, and then calculate the volume of the UV glue after curing V1 = H*L*W according to the width L of the glass and the width W of the groove;

[0110] 2) Calculate the volume V0 of the liquid glue before curing according to the volume V1 after curing: V0 = V1 / X, where X represents the content of non-volatile matter;

[0111] 3) Before dispensing glue, clean the surface of the folding screen glass to be glued to make it dry and grease-free; then perform plasma cleaning on the grooved area;

[0112] 4) Select epoxy resin UV curing glue for dispensing, dispensing parameters:

[0113] A: First dispensing: dispensing dam glue, dam glue nozzle pressure 0.4MPa, injection speed 22mm / s, glue dispensing speed 0.002mL / s, dam glue line width 1.3-1.5mm, the distance between the dam glue edge and the hole or glass edge is 0.6-0.8mm; dam glue pre-curing time 12s;

[0114] B: Second dispensing: dispensing filling glue, filling glue nozzle pressure 0.1MPa, needle injection speed 25mm / s, glue distribution speed 0.004mL / s, filling glue line width 1.2mm, filling glue pre-curing time 6s.

[0115] In order to ensure that the bonding position is fully filled with water glue without any glue deficiency, the amount of filling glue is set to 0.5%-1% greater than the amount of glue required to fill the groove area. The excess filling glue overflows from both sides of the dam glue and the groove junction area when the large and small glasses are bonded.

[0116] In the process of processing the front cover of the folding screen electronic device of the present invention, while the glass sheet to be thinned is positioned and clamped by vacuum adsorption, a first adsorption area and a second adsorption area corresponding to the grooved area 101 and the non-grooved area 102 of the glass sheet are respectively arranged on the adsorption platform 202 of the grinding machine thinning fixture 20, and an adsorption hole 203 with an aperture less than or equal to 2 mm is opened on the first adsorption area, and an air groove 204 with a width greater than the aperture of the adsorption hole 203 is opened on the second adsorption area. While the negative pressure at the second adsorption area firmly adsorbs the glass sheet to be thinned and prevents the glass sheet from shifting during the processing, the adsorption force of the grooved area 101 is reduced to avoid the glass After the grooved area 101 on the sheet is thinned, the glass thinned by the grinder may break due to excessive local adsorption force. It can also play a buffering role when the air pressure fluctuates, thereby avoiding the problem of glass breakage caused by excessive adsorption force fluctuations in the grooved area 101, reducing the glass breakage rate and defective rate, and improving the production efficiency of ultra-thin glass. In addition, the combination of grinder thinning and NaOH chemical thinning can avoid the problem of increased breakage ratio caused by the grinder groove thinning to a thickness of less than 0.08mm in the bending area of ​​the glass, and can also avoid the problem of excessive thinning and removal and increased cost caused by etching the entire glass with the NaOH system alone, thereby reducing the processing cost of ultra-thin glass.

[0117] 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.

[0118] 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 front cover processing technology, used to achieve the thinning of the bending area of ​​the front cover of the folding screen electronic device, characterized in that: The following steps are involved: S1, cutting a glass sheet to obtain a glass sheet to be processed, wherein the glass sheet has a user surface facing a user side when in use and a system surface facing the inside of the electronic device, and the system surface has a grooved area for forming a bending area and a non-grooved area located beside the grooved area; S2, prepare a grinding machine thinning fixture, wherein a vacuum air channel for communicating with an external vacuum device is provided in the grinding machine thinning fixture, an adsorption platform is formed on the upper surface of the grinding machine thinning fixture, a first adsorption area corresponding to the area to be grooved and a second adsorption area corresponding to the non-grooving area are provided on the adsorption platform, a plurality of adsorption holes connected to the vacuum air channel are provided at the first adsorption area, an air groove connected to the vacuum air channel is provided at the second adsorption area, the aperture of the adsorption hole is less than or equal to 2 mm, the width of the air groove is greater than the aperture of the adsorption hole, and the total amount of air intake in the first adsorption area per unit time is less than the total amount of air intake in the second adsorption area; S3, fixing the grinding machine thinning fixture on the grinding machine table, and clamping the glass sheet on the grinding machine thinning fixture, so that the user surface of the glass sheet is in contact with the adsorption platform, the area to be grooved of the glass sheet corresponds to the first adsorption area, and the non-grooved area of ​​the glass sheet corresponds to the second adsorption area; S4, mechanically thinning the area to be grooved on the glass sheet using a grinding wheel on a grinder; S5, using NaOH to perform double-sided thinning on the mechanically thinned glass sheet; S6. Perform PVD coating on the bending area on the glass sheet, and harden the coated glass sheet once; after de-coating the bending area, harden the glass sheet a second time to obtain a front cover of a folding screen electronic device.

2. The folding screen electronic device front cover processing technology according to claim 1 is characterized in that: After mechanical thinning, the thickness of the bending area is 0.095-0.115mm; after double-sided thinning, the thickness of the bending area is 0.03-0.05mm.

3. The folding screen electronic device front cover processing process according to claim 1 is characterized in that: The grinding wheel includes a wheel body, a through hole for passing the grinder motor shaft is opened in the middle of the wheel body, the annular side surface of the wheel body forms an annular grinding surface, and the two opposite side surfaces of the wheel body are respectively raised to form two annular steps coaxial with the through hole, the outer diameter of the annular step is smaller than the diameter of the annular grinding surface, and an arc-shaped transition portion is provided between the annular step and the annular grinding surface.

4. The folding screen electronic device front cover processing process according to claim 1, characterized in that: In step S6, after the glass sheet is hardened for the second time, glue is applied to the bending area of ​​the system surface of the glass sheet to form a glue layer, and the thickness of the glue layer is the height difference between the grooved area and the non-grooved area.

5. The folding screen electronic device front cover processing technology according to claim 1 is characterized in that: The surface roughness Ra of the upper surface of the adsorption platform is 0.003 mm, and the flatness of the glass sheet after being attached to the adsorption platform is less than 0.01 mm.

6. The folding screen electronic device front cover processing technology according to claim 1, characterized in that: The upper surface of the grinding machine thinning fixture is provided with a plurality of limit blocks which are arranged at intervals along the edge of the adsorption platform and arranged along a U-shaped path. The upper surface of the limit blocks is higher than the upper surface of the adsorption platform, and gaps are formed between adjacent limit blocks.

7. The folding screen electronic device front cover processing technology according to claim 1 is characterized in that: A plurality of adsorption holes are arranged in a square matrix in the first adsorption zone. The row spacing between the adsorption holes in the first adsorption zone is 5 mm, and the column spacing between the adsorption holes is 6.3 mm.

8. The folding screen electronic device front cover processing process according to claim 1, characterized in that: The lower surface of the grinding machine thinning fixture is provided with a hollow groove at a position corresponding to the first adsorption area, and the top surface of the hollow groove is provided with a plurality of air guide holes connected to the vacuum air duct, and each air guide hole is connected to two adjacent adsorption holes on the first adsorption area, and a shielding portion for partially shielding the adsorption hole is formed between the two adjacent air guide holes.

9. The folding screen electronic device front cover processing process according to claim 1, characterized in that: A guide hole communicating with the vacuum air passage is provided in the second adsorption area on the adsorption platform, and the guide hole is correspondingly communicated with the middle part of the air groove.

10. The folding screen electronic device front cover processing technology according to claim 9, characterized in that: The air groove comprises a plurality of annular guide grooves arranged in a circle around the guide hole as the center, each annular guide groove is connected in sequence and connected with the guide hole, and the annular guide grooves are in a square ring structure or a circular ring structure.

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