A grinding disc suitable for precise processing of watch sapphire glass and a preparation method thereof

Abstract

The application discloses a kind of grinding disc and preparation method suitable for watch sapphire glass precision machining, grinding disc, including metal matrix, adhesive layer and grinding layer, grinding layer includes multiple grinding structures, each grinding structure is spaced distribution;Grinding layer coverage is 20%-65%;Each described grinding structure is made by the compound of metal binder and diamond particle, the component of metal binder is copper tin iron alloy powder, nickel powder and graphite.The application uses copper tin iron alloy powder as main, nickel powder as auxiliary, graphite powder as the metal binder of balance and diamond particle is mixed uniformly by ball milling and sintering into shape, so that diamond particle is tightly locked when grinding hard sapphire glass, and particle will not occur separation, reduce the generation of free waste, and by changing grinding layer coverage and the granularity of diamond particle can be applicable to different machining precision demand sapphire glass grinding, effectively improve the efficiency and grinding surface quality of sapphire glass processing.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of grinding disc, and particularly relates to a grinding disc suitable for precision machining of watch sapphire glass and a preparation method. BACKGROUND

[0002] Sapphire glass with excellent mechanical and thermal properties is increasingly applied to watch mirror glass and other optical mirrors, but its high hardness and brittleness make its precision machining in industry particularly difficult, and the machining cost is high, the efficiency is low, and the overall machining effect is not ideal. The service life of traditional superhard grinding tools is short, and the surface quality of machined workpieces is poor. Ordinary electroplated and brazed products also cannot meet the current machining requirements due to insufficient service life.

[0003] In the precision machining of sapphire, a grinding method using free abrasives is often used. Although this machining method is efficient, it produces a large amount of free debris after grinding, which causes great pollution to the environment. The treatment of these pollutants becomes a great burden for manufacturers. Therefore, it is of great significance to develop a superhard grinding tool suitable for thinning and precision machining of sapphire glass. SUMMARY

[0004] The application provides a grinding disc suitable for precision machining of watch sapphire glass and a preparation method, which solves the problem of sapphire glass grinding described in the prior art.

[0005] The technical scheme adopted by the application is as follows:

[0006] A grinding disc suitable for precision machining of watch sapphire glass, comprising a metal base, an adhesive layer and a grinding layer, the grinding layer comprising a plurality of grinding structures, each grinding structure being spaced apart; the sum of the surface areas of each grinding structure is the surface area of the grinding layer, and the ratio of the surface area of the grinding layer to the surface area of the metal base is the grinding layer coverage, the grinding layer coverage being 20%-65%;

[0007] Each grinding structure is made of a composite of a metal binder and diamond particles, and the concentration of diamond particles is 50%-150%; the conversion standard of the concentration of diamond particles and the volume proportion in the composite is that when the concentration of diamond particles is 100%, the volume of diamond particles accounts for 25% of the total volume of the composite; and since 1 cm 3 The mass of the diamond particles is 0.88g, and the mass of the diamond particles corresponding to different concentrations can be obtained by conversion.

[0008] The components of the metal binder are copper-tin-iron alloy powder, nickel powder and graphite.

[0009] As a preferred scheme of the present application, the average particle size of the diamond particles in the composite is 20-125 μm; and the average particle size of the metal binder is ≤40 μm.

[0010] As a preferred scheme of the present application, the metal binder has the following components in terms of mass percentage: 80-94% of copper-tin-iron alloy powder, 3-10% of nickel powder, and the balance of graphite powder. Here, the mass percentage is only for the metal binder itself.

[0011] As a preferred scheme of the present application, the mass ratio of copper, tin and iron in the copper-tin-iron alloy powder is copper:tin:iron= (50-80) : (5-45) : (5-15). The copper-tin-iron alloy powder can be directly purchased as a finished product in the market or can be configured by oneself.

[0012] As a preferred scheme of the present application, preferably, copper:tin:iron= 68:20:12, i.e. 68Cu-12Sn-10Fe.

[0013] As a preferred scheme of the present application, the hardness of the grinding disc is in the range of HRB 60 to HRB 80.

[0014] The present application also provides a preparation method of a grinding disc suitable for precision machining of watch sapphire glass, comprising the following steps,

[0015] Preparation of materials:

[0016] Prepare the metal binder in terms of mass percentage, 80-94% of copper-tin-iron alloy powder, 3-10% of nickel powder, and 3-10% of graphite powder; and diamond particles with a concentration of 50-150%; which can be 80% copper-tin-iron alloy powder, 10% nickel powder, and 10% graphite powder; or 94% copper-tin-iron alloy powder, 3% nickel powder, and 3% graphite powder; and the copper-tin-iron alloy powder, nickel powder, and graphite powder are the metal binder, and the mass percentage is 100%; and the mass percentage of the diamond particles is calculated separately according to the required concentration.

[0017] The conversion standard of the concentration of the diamond particles and the volume ratio in the composite is that when the concentration of the diamond particles is 100%, the volume of the diamond particles accounts for 25% of the total volume of the composite; and since 1 cm 3 The mass of the diamond particles is 0.88 g, and the mass of the diamond particles corresponding to different concentrations can be obtained by conversion.

[0018] Ball milling of the mixture:

[0019] The copper-tin-iron alloy powder and the nickel powder are mixed with the graphite powder and the diamond particles after ball milling in an oxygen-free environment to obtain the composite;

[0020] Vacuum sintering:

[0021] The composite is vacuum sintered after being loaded into a mold to obtain a grinding structure;

[0022] The grinding structure is assembled onto a metal base through an adhesive layer and is trimmed.

[0023] As a preferred scheme of the present application, the copper-tin-iron alloy powder, the nickel powder and the anhydrous ethanol are put into a ball milling tank for ball milling, the ball milling speed is V1, and the ball milling time is T1.

[0024] The graphite powder and the diamond particles are added into the ball milling tank for further mixing to obtain a mixture containing the anhydrous ethanol, the ball milling speed is V2, and the ball milling time is T2.

[0025] The ball milling speed V1 is greater than the ball milling speed V2, and the ball milling time T1 is greater than the ball milling time T2; the ball milling speed V1 and the ball milling speed V2 range from 400 rpm to 600 rpm, and the ball milling time T1 and the ball milling time T2 range from 2 h to 8 h.

[0026] The anhydrous ethanol is removed by heating to obtain a uniformly mixed composite.

[0027] As a preferred scheme of the present application, the hard alloy balls are used in the ball milling tank, the sizes of the hard alloy balls are 2 mm, 5 mm and 10 mm respectively, and the mass ratio of the hard alloy balls of different sizes is M2:M5:M 10 =1:3:4; and the total volume of the hard alloy balls and the mixture accounts for 1 / 3-2 / 3 of the volume of the ball milling tank.

[0028] As a preferred scheme of the present application, the vacuum sintering machine is used in the vacuum sintering, the highest temperature of the vacuum sintering is 740°C, the heating speed is 100°C / min, the holding time at the highest temperature is 3 min-15 min, and then the temperature is cooled to room temperature at a cooling speed of 60-80°C / min.

[0029] The present application uses the copper-tin-iron alloy powder as the main component, the nickel powder as the auxiliary component and the graphite powder as the rest component to mix the metal binder and the diamond particles uniformly through ball milling and sintering, so that the diamond particles are tightly locked and cannot be separated when grinding the sapphire glass with high hardness, the generation of free waste is reduced, and the grinding of the sapphire glass with different machining precision requirements can be achieved by changing the grinding layer coverage and the particle size of the diamond particles, thereby effectively improving the efficiency of sapphire glass machining and the grinding surface quality. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only show some of the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative effort based on these drawings.

[0031] Figure 1 The structure diagram of the grinding disc of the present application.

[0032] Figure 2 The sectional view of the grinding disc of the present application. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present application.

[0034] Embodiment 1:

[0035] A preparation method of a grinding disc suitable for precision machining of watch sapphire glass, the steps are as follows,

[0036] Preparation of materials:

[0037] Prepare metal bond by mass percentage, accurately weigh 92% copper-tin-iron alloy powder, 5% nickel powder and 3% graphite powder; weigh diamond particles with a concentration of 100%; the average particle size of the diamond particles is 20-125 μm, and in this embodiment, the particle size of the diamond particles is 230 / 270#.

[0038] The copper-tin-iron alloy powder, nickel powder and graphite powder are metal bond, and the mass percentage is 100%; and the mass percentage of the diamond particles is calculated separately according to the required concentration, and the conversion standard of the volume ratio in the composite according to the concentration of the diamond particles is: when the concentration of the diamond particles is 100%, the volume of the diamond particles accounts for 25% of the total volume of the composite; and since 1 cm 3 The mass of the diamond particles is 0.88 g, and the mass of the diamond particles corresponding to different concentrations can be obtained by conversion.

[0039] Ball milling:

[0040] The copper-tin-iron alloy powder and the nickel powder are added into the ball mill tank together after being added into anhydrous ethanol, and the material in this ball milling process is in an oxygen-free environment due to the anhydrous ethanol;

[0041] The hard alloy balls are added into the ball milling tank, the sizes of the hard alloy balls are 2mm, 5mm and 10mm respectively, and the mass ratio of the hard alloy balls of different sizes is M2:M5:M6=1:3:4. 10

[0042] The total volume of the hard alloy balls, the copper-tin-iron alloy powder and the nickel powder accounts for 1 / 3-2 / 3 of the volume of the ball milling tank, the ball milling rotation speed V1 is 600rpm, and the ball milling time T1 is 4 hours.

[0043] After the mixing for 4 hours, the graphite powder and the diamond particles are added into the ball milling tank, the ball milling rotation speed V2 is 400rpm, and the ball milling time T2 is 2 hours; after the mixing for 2 hours again, the ball and the material are separated to obtain a mixture containing anhydrous ethanol; the rotation speed and the time of the two ball milling can be adjusted according to the actual situation, which can be 400rpm, 420rpm, 450rpm, 500rpm, 520rpm, 560rpm, 580rpm, etc.; the time can be 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 5 hours, 5.5 hours, 6 hours, 7 hours, 7.5 hours, 8 hours, etc.

[0044] The mixture is heated at 80°C to remove the anhydrous ethanol to obtain a uniformly mixed composite, at this time, the diamond concentration is 100%, the copper-tin-iron alloy powder, the nickel powder and the graphite powder jointly constitute the metal bond, the average particle size of which is ≤40μm, and the copper-tin-iron alloy powder is copper:sink:iron=68:20:12, i.e. 68Cu-12Sn-10Fe.

[0045] Vacuum sintering:

[0046] At room temperature, the composite is loaded into the existing graphite mold, and then is loaded into the vacuum sintering press to perform vacuum sintering, and the heating speed is 100°C / min, the temperature is raised to the highest sintering temperature of 740°C, the temperature is kept for 5min, and then is cooled to room temperature at a cooling speed of 60-80°C / min; finally, a plurality of grinding structures 4 are obtained.

[0047] The grinding structures are uniformly distributed on the metal substrate by a fixed mold to obtain a to-be-finished grinding disc, the grinding layer coverage rate is 27.5%, and the grinding structure and the metal substrate are bonded by an adhesive layer, the to-be-finished grinding disc is finished on a grinding machine, the overall flatness is within 0.02mm, the dynamic balance is within 2.0g, and the blade is opened by an oil stone.

[0048] After finishing, the final grinding disc suitable for precision machining of watch sapphire glass is obtained, and the hardness range of the grinding disc is HRB 60 to HRB 80.

[0049] A grinding disc suitable for precision machining of watch sapphire glass, such as Figure 1 and​2 As shown, it comprises a metal base 1, a bonding layer 2 and a grinding layer 3, the grinding layer 3 comprises a plurality of grinding structures 4, the grinding structure is a cylindrical structure, the size is Φ5*10mm; of course, it can also be other shapes, which is designed according to the actual demand.

[0050] Each grinding structure 4 is uniformly spaced; the sum of the surface area of each grinding structure is the surface area of the grinding layer, and the ratio of the surface area of the grinding layer to the surface area of the metal base is the grinding layer coverage, which is 20%-65%, which can be 20%, 25%, 30%, 35.8%, 40%, 43%, 52%, 55%, 62%, 65%, etc., and in this embodiment, it is 27.5%.

[0051] Each of the grinding structures is made of a composite of metal binder and diamond particles, and the concentration of diamond particles is 50%-150%, which can be 50%, 70%, 80%, 85%, 90%, 100%, 120%, 125%, 130%, 135%, 140%, 142%, 150, etc., and in this embodiment, it is 100%.

[0052] Example 2:

[0053] The diamond particle size is 325 / 400#, the grinding layer coverage is 35%, and the rest is the same as example 1.

[0054] Example 3:

[0055] The diamond particle size is 800#, the grinding layer coverage is 42%, and the rest is the same as example 1.

[0056] The grinding discs in the three examples are ground by a double-end surface grinding machine, and 15 pieces of sapphire glass are arranged on the feeding disc per disc. The grinding disc rotates at a speed of 700±100 rpm, the feeding disc rotates at a speed of 20±5 rpm, and the standard mobile phone size is selected as the processed workpiece. By adjusting the feed amount of the grinding disc, the glass removal amount is measured to obtain the processing efficiency of the grinding disc with different particle sizes and the surface roughness Sz of the glass, and the data is shown as follows:

[0057] The feed amount of the grinding disc of example 1 is 0.18mm / min, and the surface roughness SZ of the sapphire after grinding is about 8000.

[0058] The feed amount of the grinding disc of example 1 is 0.15m / min, and the surface roughness SZ of the sapphire after grinding is 6800

[0059] .

[0060] The feed amount of the grinding disc of example 1 is 0.12m / min, and the surface roughness SZ of the sapphire after grinding is 3500

[0061] left and right.

[0062] In the description of the present specification, the description referring to the terms "one embodiment", "an example", "a specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

[0063] The above description is merely preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art, according to the technical range disclosed by the present application and the inventive concept thereof, can make equivalent replacements or changes within the technical range, which should be included in the protection scope of the present application.

Claims

1. A grinding disc suitable for precision machining of sapphire glass for watches, characterized in that: It includes a metal substrate (1), an adhesive layer (2), and a polishing layer (3). The polishing layer (3) includes multiple polishing structures (4), which are spaced apart. The sum of the surface areas of each polishing structure is the surface area of ​​the polishing layer. The ratio of the surface area of ​​the polishing layer to the surface area of ​​the metal substrate is the polishing layer coverage rate, which is 20%-65%. Each of the aforementioned grinding structures is made of a composite of a metal binder and diamond particles, with the concentration of diamond particles being 50%-150%. The metal binder is composed of copper-tin-iron alloy powder, nickel powder, and graphite. The metal binder, by mass percentage, has the following components: 80%-94% copper-tin-iron alloy powder, 3%-10% nickel powder, and the balance being graphite powder. The mass ratio of copper, tin and iron in the copper-tin-iron alloy powder is copper:tin:iron = (50~80):(5~45):(5~15).

2. The grinding disc for precision machining of sapphire glass for watches according to claim 1, characterized in that: The average particle size of the diamond particles in the composite is 20 μm to 125 μm; the average particle size of the metal binder is ≤40 μm.

3. The grinding disc for precision machining of sapphire glass for watches according to claim 1, characterized in that: Copper: Tin: Iron = 68:20:

12.

4. The grinding disc for precision machining of sapphire glass for watches according to claim 3, characterized in that: The hardness range of the grinding disc is HRB 60 to HRB 80.

5. A method for preparing a grinding disc suitable for precision machining of sapphire glass for watches, as described in any one of claims 1-4, characterized in that: The steps are as follows: Preparation of materials: Prepare a metal binder by mass percentage, consisting of 80%-94% copper-tin-iron alloy powder, 3%-10% nickel powder, 3%-10% graphite powder, and 50%-150% diamond particles. Ball milling: Copper-tin-iron alloy powder and nickel powder were ball-milled in an oxygen-free environment and then mixed with graphite powder and diamond particles to obtain a composite material. Vacuum sintering: The composite was molded and then vacuum sintered to obtain a polished structure. The grinding structure is assembled onto the metal substrate and finished using an adhesive layer.

6. The method for preparing a grinding disc suitable for precision machining of sapphire glass for watches according to claim 5, characterized in that: When mixing materials in ball milling, copper-tin-iron alloy powder, nickel powder and anhydrous ethanol are put into the ball milling jar together for ball milling. The ball milling speed is V1 and the ball milling time is T1. Graphite powder and diamond particles were added to the ball mill jar and mixed to obtain a mixture containing anhydrous ethanol; the ball mill speed was V2 and the ball milling time was T2. Furthermore, the ball milling speed V1 is greater than the ball milling speed V2, and the ball milling time T1 is greater than the ball milling time T2; the range of ball milling speed V1 and ball milling speed V2 is 400-600 rpm, and the range of ball milling time T1 and ball milling time T2 is 2-8 h; Heating removes the anhydrous ethanol, yielding a homogeneous complex.

7. The method for preparing a grinding disc suitable for precision machining of sapphire glass for watches according to claim 6, characterized in that: The grinding jar uses cemented carbide balls with sizes of 2mm, 5mm, and 10mm; and the mass ratio of the different sizes of cemented carbide balls is M2:M5:M 10 =1:3:4; and the total volume of the cemented carbide balls and the mixture accounts for 1 / 3 to 2 / 3 of the volume of the ball mill jar.

8. The method for preparing a grinding disc suitable for precision machining of sapphire glass for watches according to claim 6, characterized in that: During vacuum sintering, the maximum temperature is 740°C, the heating rate is 100°C / min, and the holding time at the maximum temperature is 3min-15min; then it is cooled to room temperature at a rate of 60-80°C / min.

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