Device and method for grinding brittle workpiece
By using the same transition plate and limiting parts as the glass material, the problem of glass workpieces being easily broken during grinding is solved, and efficient and low-cost processing effect is achieved.
Patent Information
- Application Number
- CN202510888960.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-30
- Publication Date
- 2025-08-08
AI Technical Summary
In the prior art, workpieces made of glass cannot be stably fixed on the magnetic suction platform, resulting in easy breakage during grinding and difficult to ensure processing accuracy.
The workpiece is fixed with the same material as the workpiece. The transition plate is the same material as the workpiece to maintain a high fit. The limiting member is fixed on the magnetic suction platform through magnetic suction, and stress is dispersed through the buffer pad and the buffer frame to avoid breakage.
It improves the grinding efficiency of brittle workpieces, reduces processing costs, and ensures machining accuracy and workpiece integrity.
Smart Images
Figure CN120439147A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of grinding, and in particular to a grinding device and method for a brittle workpiece. Background Art
[0002] When manufacturing chips through photolithography, light is typically transmitted through a mask with a circuit pattern drawn on it. The pattern on the mask is then scaled down and projected onto the photoresist on the surface of the silicon wafer. After a series of subsequent processes, including development, hardening, and etching, the chip is finally created. The mask is the master pattern for the pattern on the wafer, so its performance directly affects the quality of the photolithography process. Masks primarily consist of two parts: a mask substrate and a light-shielding film. Quartz glass is widely used as a mask substrate for very large-scale integrated circuit (VLSI) reticles due to its chemical stability, high optical transmittance, and low thermal expansion coefficient.
[0003] The mask substrate has high requirements for flatness. Currently, a surface grinder is usually used to grind the glass workpiece of the mask substrate to improve the flatness.
[0004] like Figure 1 As shown, a surface grinder typically includes a magnetic platform 1 for placing a planar workpiece, and a grinding head 2 positioned above the magnetic platform. Workpiece A to be ground must be secured to the magnetic platform 1. Existing surface grinders are typically used to grind metal workpieces A. Metal workpieces A can be flexibly secured to the magnetic platform 1 by power, magnetization, and demagnetization and removal. Therefore, the magnetic platform 1 is typically constructed of metal. The grinding head can be pressed down onto the surface of workpiece A and moved horizontally relative to the workpiece A to grind it.
[0005] However, when workpiece A is made of glass, it cannot be magnetically fixed to magnetic platform 1. Therefore, existing techniques typically use a magnetically attracted metal block, which is tightly attached to the periphery of workpiece A. When magnetic platform 1 is energized, the metal block is magnetically fixed, thereby horizontally securing workpiece A to magnetic platform 1. However, due to the different physical properties of metal magnetic platform 1 and glass, gaps easily form between magnetic platform 1 and glass workpiece A during processing, resulting in an insufficient fit. This leads to an imbalance in the support points of magnetic platform 1 on the glass, making the glass very susceptible to breakage. Summary of the Invention
[0006] Based on this, an object of the present invention is to overcome the defects or shortcomings of the prior art and provide a grinding device for brittle workpieces.
[0007] A grinding device for brittle workpieces, comprising a grinding machine, which includes a magnetic platform and a grinding head moving above the magnetic platform; a transition plate for placing the workpiece, which is fixed on the magnetic platform and made of the same material as the workpiece; a limiting member, which includes a positioning seat and an abutment block arranged on the top of the positioning seat; the positioning seats of at least two limiting members can be magnetically fixed to the magnetic platform and attached to the side wall of the transition plate, and the abutment block can rotate relative to the top surface of the positioning seat and abut against the side edge of the workpiece placed on the transition plate.
[0008] Compared to existing technologies, the introduction of a transition plate made of the same material as the workpiece to support the workpiece creates a closer fit, minimizing breakage during the grinding process. This tighter fit between the workpiece and the transition plate also prevents particles and debris generated during the grinding process from entering the gap between the workpiece and the transition plate, causing unevenness and thus impacting machining accuracy. Furthermore, the stopper can cooperate with the transition plate to flexibly secure the workpiece to it, significantly improving machining efficiency for brittle workpieces and reducing machining costs.
[0009] In one embodiment, the transition plate is provided with at least one slit, and at least one stopper is disposed within the slit. The stopper's positioning seat is movable along the slit, embedded within the slit, and magnetically fixed to the magnetic platform. The stopper's abutment block is rotatable relative to the top surface of the positioning seat and abuts against a side edge of a workpiece placed on the transition plate. The stopper located within the slit can abut against a side edge of the workpiece located in the middle of the transition plate, thereby enhancing the stopper's retaining effect on the workpiece.
[0010] In one embodiment, the transition plate is rectangular, and the slits are located at the diagonals of the transition plate. The slits located at the diagonals make it easier for the position limiter to flexibly adjust its position according to workpieces of different sizes.
[0011] In one embodiment, a buffer pad is provided on the side wall of the abutting block of the limiting member that abuts against the workpiece.
[0012] In one embodiment, a buffer frame is further included, which is used to cover the side of the workpiece; when the abutment block of the limit member abuts the workpiece, the buffer frame is abutted between the workpiece and the abutment block. The buffer pad and the buffer frame are used to disperse stress and further prevent the workpiece from cracking.
[0013] In one embodiment, the workpiece is a glass workpiece, and the transition plate is a glass transition plate.
[0014] In one embodiment, the flatness of the upper surface of the transition plate is less than 5 μm, and the flatness of the lower surface is less than 20 μm. The excellent flatness of the transition plate is more conducive to grinding the workpiece to a good flatness.
[0015] In one embodiment, the thickness of the transition plate is greater than or equal to 30 mm, and the flatness of the upper surface of the magnetic platform is less than 20 μm. The sufficiently flat magnetic platform and thick transition plate can prevent deformation of the transition plate, further ensuring that the workpiece can achieve excellent flatness.
[0016] In one embodiment, a feeler gauge is positioned between the transition plate and the workpiece. During the initial machining phase, the feeler gauge fills the gap between the workpiece and the magnetic platform, providing a support point and preventing excessive vibration amplitude during machining, which could result in large machining errors or breakage.
[0017] Another object of the present invention is to provide a method for grinding a brittle workpiece, comprising the following steps:
[0018] A transition plate made of the same material as the workpiece is provided, and the first surface of the transition plate is polished to a flatness of less than 20 μm;
[0019] Then, the transition plate is fixed on the magnetic platform of the grinding device so that the second surface of the transition plate is in close contact with the magnetic platform;
[0020] Then, the first surface of the transition plate is polished to a flatness of less than 5 μm;
[0021] placing the workpiece on the first surface of the transition plate so that the two are in contact with each other;
[0022] A plurality of limiting members are provided, each of which includes a positioning seat and an abutment block provided on the top of the positioning seat and rotatable relative to the top surface of the positioning seat; the positioning seat is magnetically fixed to the magnetic platform and attached to the side wall of the transition plate, and the abutment block is rotated to abut against the side edge of the workpiece placed on the transition plate;
[0023] The two sides of the workpiece are roughly trimmed to a flatness of less than 40 μm by a grinding head of a grinding processing device, and then finely trimmed to a flatness of less than 10 μm.
[0024] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 It is a structural schematic diagram of the surface grinder described in the background technology;
[0026] Figure 2 Schematic diagram of the structure of a grinding device for a brittle workpiece in one embodiment of the present invention;
[0027] Figure 3 This is an exploded view of the limiting member when the abutment block and the positioning seat form an angle;
[0028] Figure 4 This is a schematic diagram of the assembly of the limiting member when the abutment block is parallel to the positioning seat;
[0029] Figure 5 A schematic diagram of a placement method of a position limiting member in an embodiment;
[0030] Figure 6 A three-dimensional schematic diagram of the placement of the limiter when the transition plate has a slit;
[0031] Figure 7 This is a top view of the placement of the limiter when the transition plate has a slit;
[0032] Figure 8 This is a top view schematic diagram of the placement of the limit parts when the transition plate has two slits. DETAILED DESCRIPTION
[0033] To prevent the breakage of brittle workpieces like glass, the present invention incorporates a transition plate made of the same material as the workpiece. This transition plate is fixed to a magnetic platform and serves as a support for the workpiece. Since the workpiece and the transition plate share similar physical properties, such as thermal expansion, they maintain a high degree of contact during machining, thus preventing the glass workpiece from breaking. Furthermore, the present invention incorporates a stopper to quickly secure or remove the workpiece from the transition plate.
[0034] The solution of the present invention is described in detail below with reference to the accompanying drawings.
[0035] See also Figure 2 The grinding apparatus for brittle workpieces of the present invention includes a surface grinder, a transition plate 30, and a stopper 40. The surface grinder includes a magnetic platform 10 and a grinding head 20 that moves above the magnetic platform 10. The surface grinder in this embodiment is specifically a surface gantry grinder. The transition plate 30 is fixed on the magnetic platform 10 and is used to place a glass workpiece B. The transition plate 30 is used to fix the glass workpiece B on the transition plate 30. The grinding head 20 is used to grind the glass workpiece B.
[0036] Specifically, such as Figure 3 、 4As shown, the limiting member 40 includes a positioning seat 41 and an abutment block 42 arranged on the top of the positioning seat 41. The positioning seat 41 is a cubic block structure, and the material is a material that can be attracted by a magnet, including iron (Fe), cobalt (Co), nickel (Ni) and their alloys. Then, when the magnetic platform 10 is energized and excited, the positioning seat 41 can be adsorbed and fixed on the magnetic platform. The abutment block 42 is also a cubic block structure, which is arranged on the top surface of the positioning seat and can rotate along the top surface of the positioning seat. In one embodiment, a screw hole 41 is provided on the top of the positioning seat 41, and a through hole 42a is provided on the abutment block 42. A screw rod 43a of a screw 43 passes through the through hole 42a of the abutment block 42 and is screwed into the screw hole 41 of the positioning seat 41 to connect the two. When the screw 43 is loosened, the abutment block 42 can rotate freely on the top of the positioning seat 41 with the screw rod 43a of the screw 43 as the rotation axis; when the screw 43 is tightened, the screw head 43b of the screw 43 is pressed against the top of the positioning seat 41 from the top of the abutment block 42, so that the abutment block 42 is fixed on the positioning seat 41.
[0037] The positioning seat 41 is disposed on the magnetic platform and is in close contact with the side wall of the transition plate 30. At this point, the top surface of the positioning seat 41 is flush with the upper surface of the transition plate 30, so that the bottom surface of the abutment block 42 located on the positioning seat 41 is higher than the upper surface of the transition plate 30. The abutment block 42 can then rotate along the axis of the screw 43 above the transition plate 30 to adjust to different steering angles for abutment against the side edge of the glass workpiece B placed on the transition plate 30. Furthermore, the combined thickness of the screw 43 and abutment block 42 of the position-limiting member 40 is preferably less than the thickness of the glass workpiece B to prevent the screw head 43b of the position-limiting member 40 from protruding from the upper surface of the glass workpiece B, thereby preventing the grinding head 20 from being damaged by the protruding screw head 43b during grinding of the glass workpiece B.
[0038] Furthermore, in order to disperse the stress when the abutting block 42 abuts against the glass workpiece B and absorb the impact energy, and avoid the glass workpiece B from bursting, as shown in FIG. Figure 4 As shown, a buffer pad 42b is provided on the side wall of the abutting block 42 of the limiting member 40 that abuts against the glass workpiece B. The buffer is a rubber sheet or a silicone sheet. Alternatively, as Figure 5 As shown, a buffer frame 44 is provided for covering the side of the glass workpiece B. The buffer frame 44 is made of rubber or silicone. When the abutment block 42 of the limiting member 40 abuts against the glass workpiece B, the buffer frame 44 is abutted between the glass workpiece B and the abutment block 42.
[0039] In this embodiment, since the glass workpiece B is rectangular, the transition plate 30 is a rectangular glass transition plate 30. The transition plate 30 is fixed to the magnetic platform 10 by adhesive; or, a metal edging that can be magnetically attracted is inlaid on the bottom surface of the transition plate 30, and when the magnetic platform 10 is energized, the transition plate 30 is fixed to the magnetic platform 10 by adsorption of the metal edging. In order to ensure that the glass workpiece B can be ground to a better flatness, the first surface of the transition plate 30 that contacts the glass workpiece B should also achieve a better flatness. According to experimental conclusions, when the target flatness of the glass workpiece B is below 10μm, the flatness of the first surface of the transition plate 30 should be less than 5μm. In addition, if the contact surface between the transition plate 30 and the magnetic platform 10 is uneven, the transition plate 30 will also deform when the grinding head 20 presses down, causing processing errors. Therefore, the flatness of the second surface of the transition plate 30 in contact with the magnetic platform 10 should be less than 20 μm. Correspondingly, the flatness of the surface of the magnetic platform 10 in contact with the transition plate 30 should also be processed to be less than 20 μm.
[0040] In the present invention, the term flatness is used to characterize the maximum deviation of a plane on the surface of a material from an ideal plane in all directions. The smaller the flatness value, the better the flatness. In actual engineering measurements, a micrometer, a three-coordinate measuring instrument, or a spirit level is generally used to measure the height of each point on the plane, and the height difference between the most convex point and the most concave point of the plane is usually used to approximately reflect the flatness level of the plane. Among them, the micrometer and the spirit level are generally used to measure the flatness of the magnetic platform 10 or the flatness of the workpiece placed on the magnetic platform 10; the three-coordinate measuring instrument generally measures the flatness of the workpiece that has been removed from the magnetic platform 10.
[0041] Considering that the thermal expansion coefficient of the magnetic platform 10 is approximately 20 times that of quartz glass, and also considering that thinner materials are more susceptible to deformation, during the grinding process, factors such as water viscosity, surface tension, and self-weight deformation may align with the grinding machine's processing plane, resulting in the appearance of good flatness on the grinder. After being removed from the grinder and revealing its true shape, the flatness is actually worse. Therefore, in order to ensure that the flatness of the upper surface of the transition plate can reach the required level below 5μm, the present invention also provides a thickness of the transition plate 30 greater than or equal to 30mm. By increasing the thickness, the processing errors caused by the above factors are isolated, and the interference caused by the deformation of the transition plate 30 during the flatness correction of the first surface is reduced, so that the transition plate 30 can be more easily processed to a flatness below 5μm. Ultimately, within this thickness range, when the transition plate 30 is ground to correct its flatness, it can more easily achieve a flatness below 5μm, and it is not easily broken during repeated grinding and use.
[0042] Furthermore, considering that the flatness of the glass workpiece B is relatively poor in the initial stages of grinding, a large gap will exist between the glass workpiece B and the transition plate 30. The position and size of this gap vary. If left unchecked, the glass workpiece B will deform and conform to the transition plate 30 during the grinding process, resulting in a phenomenon where the flatness of the glass workpiece B appears to improve, but in reality deteriorates. Therefore, a feeler gauge is added to the grinding apparatus for brittle workpieces. A technician determines the size of the gap and inserts the feeler gauge into the gap between the glass workpiece B and the transition plate 30 to support the glass workpiece B and prevent deformation. As both sides of the glass workpiece B are continuously ground and their flatness is optimized, the gap between the glass workpiece B and the transition plate 30 gradually decreases to the point where the feeler gauge is no longer necessary.
[0043] When the device provided by the present invention is used to grind the glass workpiece B, Figure 5 As shown, two adjacent sides of the glass workpiece B are defined as the first side B1 and the second side B2 of the glass workpiece B. The rectangular glass workpiece B is placed on the transition plate 30, such that the adjacent first side B1 and the second side B2 of the glass workpiece B are aligned with the adjacent first side wall 31 and the second side wall 32 of the rectangular transition plate 30, respectively. At this point, the third side B3 of the glass workpiece B is adjacent to the second side B2, and the fourth side B4 is adjacent to the first side B1. Several stoppers 40 are placed on the magnetic platform 10, with the positioning seats 41 of at least two of the stoppers 40 respectively abutting the middle portions of the first side wall 31 and the second side wall 32 of the transition plate 30, and the abutting blocks 42 of the two stoppers 40 are parallel to the positioning seats 41. Thus, the abutting blocks 42 of the two stoppers 40 respectively abut against the first side B1 and the second side B2 of the glass workpiece B. At the same time, two stoppers 40 are provided. Their positioning seats 41 respectively abut the end of the first side wall 31 of the transition plate 30 near the fourth side wall and the end of the second side wall 32 near the third side wall. The abutment blocks 42 of the two stoppers 40 are perpendicular to their positioning seats 41. Thus, the abutment blocks 42 of the two stoppers 40 abut the fourth side edge B4 and the third side edge B3 of the glass workpiece B, respectively. In this way, the glass workpiece B is secured to the transition plate 30. The grinding head 20 is pressed down onto the upper surface of the glass workpiece B and then moved horizontally to grind. Because all four sides of the glass workpiece B are abutted and fixed by the stoppers 40, it prevents slipping or loosening. At the same time, the upper surface of the transition plate 30 adheres to and supports the glass workpiece B, preventing it from deforming or breaking. At the beginning of processing, technicians set a feeler gauge in the gap between the glass workpiece B and the transition plate 30 to ensure support for the glass workpiece B and prevent it from breaking. After improving the flatness of both sides of the glass workpiece B through multiple flipping and grinding, the glass workpiece B directly contacts the transition plate 30 in the later stage of processing. The transition plate 30 with excellent flatness fits the glass workpiece B, preventing the glass workpiece B from deformation and breakage, which is conducive to the gradual grinding of the glass workpiece B to a better flatness.
[0044] Furthermore, to accommodate a wider range of glass workpieces B of varying sizes, the transition plate 30 typically needs to be larger than the glass workpiece B. This prevents the stopper 40 from properly contacting the side of the glass workpiece B in the middle of the transition plate 30, resulting in a less secure hold of the workpiece B by the stopper 40. Therefore, to ensure that the stopper 40 can more securely secure the glass workpiece B and adapt to various sizes, the transition plate 30 is further provided with at least one slit 30a, within which at least one stopper 40 is located. In this embodiment, the slits 30a are provided at both diagonals of the rectangular transition plate 30. The positioning seat 41 of the stopper 40 is movable along the slit 30a and embedded within the slit 30a. The slit 30a extends through the upper and lower surfaces of the transition plate 30, allowing the positioning seat 41 of the stopper 40 to remain magnetically fixed by the magnetic platform 10 within the slit 30a. The abutting block 42 of the limiting member 40 can rotate relative to the top surface of the positioning seat 41 and abut against the side edge of the glass workpiece B placed on the transition plate 30 .
[0045] like Figure 6 、 Figure 7 As shown, when the slit 30a passes only below the third side B3 or the fourth side B4 of the glass workpiece B, a limiting member 40 is provided in the slit 30a. The abutting block 42 of the limiting member 40 forms an angle with its positioning seat 41 and abuts against the third side B3 or the fourth side B4 of the glass workpiece B.
[0046] like Figure 8 As shown, when the slit 30a passes under the third side B3 and the fourth side B4 of the glass workpiece B at the same time, two limiting members 40 are set in the slit 30a, and the abutting blocks 42 of the two limiting members 40 also form an angle with their positioning seats 41 and abut against the third side B3 and the fourth side B4 of the glass workpiece B respectively.
[0047] By providing a slit 30 a on the transition plate 30 and disposing a stopper 40 in the slit 30 a , the side of the glass workpiece B located in the middle of the transition plate 30 can be abutted and stopped, further enhancing the stability of the glass workpiece B when fixed on the transition plate 30 .
[0048] In some alternative embodiments, the transition plate 30 may be provided with multiple slits 30a parallel to the first sidewall 31 and the second sidewall 32 of the transition plate 30, forming a crisscrossing network structure. The stoppers 40 disposed within each slit 30a can be slidably adjusted within the slit 30a to ensure that as many of the stoppers 40 as possible abut against the side edges of the glass workpiece B, thereby enhancing the retaining effect on the glass workpiece B.
[0049] In other modified embodiments, the shape of the transition plate 30 can also be adaptively set according to the different shapes of the glass workpiece B. For example, a trapezoidal transition plate 30 can be set for a triangular glass workpiece B, and a circular transition plate 30 can be set for a circular glass workpiece B. In combination with a plurality of staggered slits 30a set on the transition plate 30, the limiting member 40 can be pressed against the side of the glass workpiece B to fix it horizontally.
[0050] Taking JGS1 quartz glass with a size of 800*960*13mm as the glass workpiece B as an example, a grinding method for a brittle workpiece is described in detail below, including the preparation steps of the grinding device for a brittle workpiece provided by the present invention and the specific steps of using the device to grind the glass workpiece B.
[0051] S1: Grinding the surface flatness of the magnetic platform 10 to below 20 μm.
[0052] A 300-grit diamond grinding wheel was used as the grinding head 20 of the plane gantry grinder to trim the flatness of the upper surface of the magnetic platform 10. An electronic level was used to test the flatness during the correction process, and the flatness of the magnetic table was trimmed to below 20 μm.
[0053] S2: Grind the transition plate 30 until the flatness of both sides is less than 20 μm.
[0054] S201: A piece of JGS1 quartz glass measuring 1600 mm (length) by 1200 mm (width) by 50 mm (thickness) was selected as the transition plate 30. The edges and corners of the base material were manually chamfered using a 150-grit oilstone to prevent sharp edges from cutting hands and to prevent edges, edges, and corners from chipping and cracking during processing. A three-dimensional coordinate measuring machine was used to test the flatness of the upper and lower surfaces (hereinafter referred to as the first and second surfaces) bounded by the long and wide sides of the rectangular transition plate 30. In this embodiment, the test results showed that the flatness of the first surface of the transition plate 30 material was 340 μm, and the flatness of the second surface was 300 μm.
[0055] S202: Place the transition plate 30 material with the first surface facing upward in the center of the magnetic table of the plane gantry grinder. Place magnetic blocks against the four sides of the transition plate 30 material, surrounding it. Turn on the magnetic switch so that the transition plate 30 material is firmly fixed by the magnetic blocks and does not move horizontally. Use a 150-grit grinding wheel as the grinding head 20 to grind the first surface of the transition plate 30 material. Set the CNC parameters as follows: a single vertical feed of 10 μm, a total vertical feed of half the flatness of the machined surface (for example, if the flatness of the first surface of the transition plate 30 to be machined is 340 μm, the total feed is set to 170 μm). Set the grinding wheel operation mode to step-by-step horizontal feed, bidirectional double horizontal feed, and a single horizontal feed of 2 / 3 of the grinding wheel width. In this embodiment, the grinding wheel width is 50 mm, and the single horizontal feed is 33 mm. After tool setting, start the equipment grinding process. After grinding, fix it on the grinding wheel protection cover with a magnetic micrometer, manually control the moving grinding wheel, and use the magnetic micrometer to measure the flatness of the first surface of the transition plate 30 material.
[0056] S203: Turn the transition plate 30 over and machine the second surface in the same manner as in step S202. The total vertical feed rate in the CNC parameters is set to half the flatness of the second surface. After grinding, the flatness is measured using a magnetic micrometer.
[0057] S204: If the flatness of the first surface and the second surface of the transition plate 30 material is still greater than or equal to 20 μm after S202 and S203, repeat steps S202-S203 until the flatness of the first surface and the second surface are both less than 20 μm.
[0058] S3: Cutting a slit 30a on the transition plate 30:
[0059] Remove the transition plate 30 material and cut slits 30a along the diagonal cuts. In this embodiment, the slits 30a extend along both diagonals, i.e., a 50mm width of material is removed at the diagonals. At this point, the transition plate 30 material is cut into four separate panels.
[0060] S4: Fix the transition plate 30 on the magnetic platform 10:
[0061] Coat the second sides of the four separate panels cut from the transition plate 30 with strong glue and affix them downward to the magnetic platform 10. Position the four panels so that they form a rectangular transition plate 30 with 50mm wide slits 30a at the two diagonals, totaling 1600mm (length) by 1200mm (width). After the glue cures, remove any excess glue from the magnetic platform. At this point, the second side of the transition plate 30 is its lower surface facing the magnetic platform 10, while the first side is its upper surface facing away from the magnetic platform 10.
[0062] S5: Processing the flatness of the first surface (ie, the upper surface) of the transition plate 30 to a flatness of less than 5 μm.
[0063] Use a magnetic micrometer to fix it on the grinding wheel protection cover, use the handwheel to control the movement of the grinding wheel position, use the micrometer to measure the high and low point difference, and record the data.
[0064] A 300-grit grinding wheel was selected as the grinding head 20 to further grind the first surface of the transition plate 30. The machining program parameters were set as follows: a single vertical feed of 3 μm, a total vertical feed of 5 μm equal to the flatness of the first surface, and a step-by-step horizontal feed of 33 mm. The upper surface of the transition plate 30 was polished. After polishing, the polishing knife was passed twice: the horizontal feed was reduced to 0 to remove any residual machining on the upper surface of the transition plate 30 and further improve the surface roughness.
[0065] After tool setting, start the machine. After machining is complete, secure the magnetic dial indicator to the grinding wheel guard. Use the handwheel to control the grinding wheel's position. Use the dial indicator to measure the flatness of the upper surface of the transition plate 30 and record the readings. If the flatness of the first surface is greater than or equal to 5μm, continue grinding until the flatness is less than 5μm, completing the flatness correction of the first surface of the transition plate 30.
[0066] S6: Use the limiting member 40 to fix the glass workpiece B horizontally on the transition plate 30 .
[0067] The glass workpiece B to be processed in this embodiment is JGS1 quartz glass with a size of 960 (length) * 800 (width) * 13 (thickness) mm. First, a three-dimensional coordinate measuring machine is used to test the flatness of the first and second surfaces of the glass workpiece B, which are surrounded by the long side and the wide side. The test results of this embodiment show that the flatness of the first surface of the glass workpiece B is 100 μm, and the flatness of the second surface is 100 μm. The glass workpiece B is placed on the first surface of the transition plate 30. Figure 7 As shown, the adjacent first side B1 and second side B2 of the glass workpiece B are aligned with the adjacent first side wall 31 and second side wall 32 of the transition plate 30, respectively. At this time, one slit 30a of the transition plate 30 passes under the third side B3 of the glass workpiece B, and the other slit 30a passes under the third side B3 and the fourth side B4 of the glass workpiece B in sequence.
[0068] The limiting member 40 is placed on the magnetic platform 10, wherein the positioning seats 41 of the positioning members of at least two limiting members 40 are respectively attached to the first side wall 31 and the second side wall 32 of the transition plate 30, and the abutting blocks 42 thereof abut the first side edge B1 and the second side edge B2 of the glass workpiece B placed on the transition plate 30.
[0069] In addition, a stopper 40 is placed in the slot 30a that passes only below the third side B3 of the glass workpiece B. The angle of its abutment block 42 is adjusted by rotation so as to abut against the third side B3 of the glass workpiece B. Two stoppers 40 are placed in the slots 30a that pass sequentially below the third side B3 and the fourth side B4 of the glass workpiece B, and the abutment blocks 42 of the two stoppers 40 abut against the third side B3 and the fourth side B4 of the glass workpiece B, respectively.
[0070] The magnetic platform 10 is electrified and excited, and the limiter 40 is magnetically fixed on the magnetic platform 10 . The glass workpiece B is horizontally fixed on the transition plate 30 because the four sides are restrained by the limiters 40 .
[0071] S7: Use a feeler gauge to fill the gap between the glass workpiece B and the transition plate 30.
[0072] The technician observes and determines whether there is a gap between the glass workpiece B and the transition plate 30 and the position of the gap, and selects a feeler gauge of appropriate size to fill the gap so that the glass workpiece B does not warp or shake.
[0073] S8: Use the grinding head 20 to perform rough flatness correction on both sides of the glass workpiece B until the double-sided flatness is less than 40 μm.
[0074] A 150-grit grinding wheel was selected as the grinding head 20 of the grinding machine to grind the first surface of the quartz glass workpiece B. The CNC parameters were set to a single vertical feed of 10 μm, and the total vertical feed was set to half of the first surface flatness result (for example, if the flatness of the first surface is 100 μm, the total feed should be as low as 50 μm). The grinding wheel operation mode was set to step-by-step horizontal feed, with bidirectional double horizontal feed. The single horizontal feed was set to 2 / 3 of the grinding wheel width. For example, if the grinding wheel width is 50 mm, the single horizontal feed is 33 mm. After tool setting, the equipment was started for processing. After processing, a magnetic micrometer was attached to the grinding wheel guard and fixed. The handwheel controlled the grinding wheel position and movement, and the micrometer was used to measure the flatness of the first surface.
[0075] Turn over and perform rough trimming on the second side of the glass workpiece B in the same manner, and change the total vertical feed amount setting to half of the flatness of the second side.
[0076] Repeatedly rough-tune the flatness of the first and second surfaces of the glass workpiece B until both surfaces achieve a flatness of less than 40 μm. During this process, technicians continuously observe the gap between the glass workpiece B and the transition plate 30. As the flatness improves, the use of feeler gauges is appropriately reduced. If the gap cannot be filled, the feeler gauge is not used.
[0077] S9: Use the grinding head 20 to fine-tune the flatness of both sides of the glass workpiece B until the double-sided flatness is less than 10μm. Replace the 500-grit grinding wheel on the plane gantry grinder as the grinding head 20, set the CNC parameters to a single vertical feed of 2μm, and the total vertical feed is half of the flatness of the machined surface. Set the grinding wheel operation mode to step-by-step horizontal feed, unidirectional single horizontal feed, and a single horizontal feed of 17mm. After tool setting, start the equipment processing. Refer to this process and repeat the processing of the first and second surfaces of the glass workpiece B three times in turn to finally obtain the ground quartz glass workpiece B.
[0078] The flatness of both sides of the final glass workpiece B was accurately measured using a three-coordinate measuring machine. The results showed that the flatness of both the first and second surfaces of the glass workpiece B was below 10μm, and no cracks were observed.
[0079] Furthermore, the apparatus and method of the present invention are also applicable to grinding other brittle workpieces. When used to grind other brittle workpieces, the material of the transition plate 30 varies with the workpiece material, and the flatness requirements of both sides of the transition plate 30 and the magnetic platform 10 can be adjusted based on the workpiece processing requirements.
[0080] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present application. The singular forms of "a", "said" and "the" used in the embodiments of the present application and the claims are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that, unless otherwise specified, "multiple" refers to two or more; the terms "first", "second", etc. are only used to distinguish, and are not used to describe a specific order or sequence, nor can they be understood to indicate or imply relative importance. The term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items. When the above description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. In the description of the present application, for those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.
[0081] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.
Claims
1. A grinding device for brittle workpieces, characterized in that: include: A grinding machine comprising a magnetic platform and a grinding head moving above the magnetic platform; A transition plate for placing the workpiece, which is fixed on the magnetic platform and made of the same material as the workpiece; A limiting member, comprising a positioning seat and an abutment block arranged on the top of the positioning seat; The positioning seats of at least two limiting members can be magnetically fixed on the magnetic platform and attached to the side walls of the transition plate. The abutment block can rotate relative to the top surface of the positioning seat and abut against the side edge of the workpiece placed on the transition plate.
2. The grinding device for brittle workpieces according to claim 1, characterized in that: At least one slit is provided on the transition plate, and at least one limiting member is provided in the slit. The positioning seat of the limiting member can be moved along the slit and embedded in the slit, and can be magnetically fixed on the magnetic platform. The abutment block of the limiting member can rotate relative to the top surface of the positioning seat and abut against the side edge of the workpiece placed on the transition plate.
3. The grinding device for brittle workpieces according to claim 2, characterized in that: The transition plate is rectangular, and the slits are located at the diagonal lines of the transition plate.
4. The grinding device for brittle workpieces according to claim 3, characterized in that: A buffer pad is provided on the side wall where the abutting block of the limiting member abuts against the workpiece.
5. The grinding device for brittle workpieces according to claim 3, characterized in that: It also includes a buffer frame covering the side of the workpiece; when the abutment block of the limiting member abuts against the workpiece, the buffer frame is abutted between the workpiece and the abutment block.
6. The grinding device for brittle workpieces according to claim 4 or 5, characterized in that: The workpiece is a glass workpiece, and the transition plate is a glass transition plate.
7. The grinding device for a brittle workpiece according to claim 6, characterized in that: The flatness of the first surface of the transition plate facing the workpiece is less than 5 μm, and the flatness of the second surface of the transition plate facing the magnetic attraction platform is less than 20 μm.
8. The grinding device for a brittle workpiece according to claim 7, characterized in that: The thickness of the transition plate is greater than or equal to 30 mm, and the flatness of the upper surface of the magnetic attraction platform is less than 20 μm.
9. The grinding device for a brittle workpiece according to claim 8, characterized in that: Also included is a feeler gauge, which is arranged in the middle gap between the transition plate and the workpiece.
10. A grinding method for a brittle workpiece, characterized in that: The steps are as follows: A transition plate made of the same material as the workpiece is provided, and both sides of the transition plate are polished alternately until the first side of the transition plate is polished to a flatness of less than 20 μm; Then, the transition plate is fixed on the magnetic platform of the grinding device so that the second surface of the transition plate is in close contact with the magnetic platform; Then, the first surface of the transition plate is polished to a flatness of less than 5 μm; placing the workpiece on the first surface of the transition plate so that the two are in contact with each other; A plurality of limiting members are provided, each of which includes a positioning seat and an abutment block provided on the top of the positioning seat and rotatable relative to the top surface of the positioning seat; the positioning seat is magnetically fixed to the magnetic platform and attached to the side wall of the transition plate, and the abutment block is rotated to abut against the side edge of the workpiece placed on the transition plate; The two sides of the workpiece are roughly trimmed to a flatness of less than 40 μm by a grinding head of a grinding processing device, and then finely trimmed to a flatness of less than 10 μm.