KR20120048769A - Grinding method for the glass of mobile phone - Google Patents

Abstract

PURPOSE: A method for grinding a glass of a cellular phone is provided to prevent cracks on a ground surface and secure a favorable surface roughness by using an electrodeposited diamond grindstone. CONSTITUTION: A method for grinding a glass of a cellular phone is as follows. A particle(2) of a diamond is joined to a nikel-plated layer(3) deposited on the surface of a grinding unit of a grindstone body(5). A plated layer with wear resistance and non-adhesive property higher than the nikel-plated layer is adhered on a surface of the nikel-plated layer so that two deposited layers are formed. The plated layer on the surface of the nikel-plated layer is formed by processing with Ni(Nickel)-P(Phosphorus) alloy at a thickness of 25 to 30 micron meters by an electroplating method. A Ni-P-plated layer(4) is ground by a diamond grindstone(1) at a speed of 1100 to 1200m/min, a material removal rate of 70 to 130(mm3/min-mm), and a table transfer speed of 7 to 13m/min.

Description

Grinding method for glass for mobile phones {Grinding method for the glass of mobile phone}

According to the present invention, when grinding glass for mobile phones using electrodeposited diamond grindstones, the electrodeposited diamond grindstones have a long service life, high processing efficiency, no cracking of the grinding surface, and good grinding of the grinding surface of the mobile phone glass. It is about a method.

Workpiece glass, which is a workpiece, is an important component constituting a mobile phone. Recently, a large amount of mobile phone glass is used, and a large amount of mobile phone glass has been manufactured. Since the glass for mobile phones has very high hardness and brittleness, even if high hardness particles such as CBN are used as the particles of electrodeposited grindstone, the tool life due to abrasion is very short, so the diamond particles having the highest hardness constitute the electrodeposited grindstone. It has been mainly used as a material, and in order to form a plating layer for supporting diamond particles, a method of electroplating only one layer of nickel has been mainly adopted.

When grinding the glass material for mobile phones using diamond electrodeposited grindstone, the hardness of the glass for mobile phones is very high, and the nickel plating layer is also abraded in a short time by contacting the workpiece with the diamond particles. This wear phenomenon of the plating layer is remarkable compared to the grinding of other materials. When the nickel plating layer is abraded, the thickness of the plating layer supporting the diamond particles becomes thinner, and the supporting force of the nickel plating layer supporting the diamond particles is weakened. Therefore, the diamond particles fall off from the plating layer. In the conventional electrodeposited diamond grindstone, since the diamond particles are formed in one layer, the dropping of the diamond particles has a problem of significantly lowering the tool life.

As described above, the diamond electrodeposited grindstone for glass grinding for mobile phones is nickel plated in one layer, and since the hardness is low, wear of the bond layer is considerably fast and diamond particles fall off. In addition, since nickel plating has low non-adhesiveness, cutting chips tend to adhere to the surface of the bond layer, and there is a problem of poor grinding performance.

Conventionally, when grinding materials having high hardness and brittleness such as glass using electrodeposited diamond grindstones, the grinding resistance is considerably large, and the above high grinding resistance in grinding of hard materials using electrodeposited diamond grindstones results in the reduction of diamond particles. It is a well-known fact that dropout is remarkably occurring. It is also known that dropping of diamond particles has a significant effect on the life of electrodeposited grindstones in grinding of materials with high hardness and brittleness, such as glass for mobile phones.

As a means for suppressing the dropping of such diamond particles, as shown in Japanese Patent Publication No. 63-72466, nickel plating by electrodeposition plating and Ni-P alloy plating by chemical plating are alternately performed. Ni-P alloy plating by electroplating and nickel-plating by the electroplating method on the surface of the grinding part of the grindstone as in Japanese Patent Publication No. Hei 8-22507, after forming a multi-layered plating layer of two or more layers. Are alternately performed to form four multi-layered plating layers and subjected to heat treatment, as described in Japanese Patent Application Laid-open No. Hei 8-309666, nickel plating by electrodeposition plating is performed on the surface of the grinding part of the grindstone body, and Ni by chemical plating is applied. -P alloy plating layer as an intermediate layer, the plating layer is formed into three layers by heat-treating nickel plating by electrodeposition plating method, and heat treatment is performed. The method has been proposed. However, these methods are effective in improving the bonding strength of the diamond particles, but because the plating process is very complicated and additional heat treatment has to be performed, there are many problems in practical use because the manufacturing cost is too high.

In addition, when grinding glass for mobile phones using electrodeposited diamond grindstones, the grinding conditions are not appropriate, resulting in shortening the life of electrodeposited diamond grindstones, cracking of the workpiece glass, and poor surface roughness. There has been little conventional research on the grinding process, which makes it very difficult to derive the appropriate grinding conditions.

The present invention has been made to solve the above problems, when grinding the glass for mobile phones using electrodeposited diamond grindstone, long grindstone life, high processing efficiency, no cracking on the grinding surface, It is an object of the present invention to provide a method for grinding a glass for mobile phones having good surface roughness.

The grinding method of the glass for mobile phones of this invention is the electrodeposited grindstone in which the diamond particle is couple | bonded with the nickel plating layer deposited on the surface of a grindstone main body, The surface of the said nickel plating layer has a plating layer which is more excellent in abrasion resistance and non-tackiness than the nickel plating layer. It is characterized by using an electrodeposited diamond grindstone formed of two layers of electrodeposition layers by deposition. The electrodeposited diamond grindstone used in the present invention is a plating layer deposited on the surface of the nickel plating layer, which is a lower layer, and Ni-P alloy is formed to have a thickness of 25 to 30 µm by electroplating, and Ni-P forming an upper layer of the nickel plating layer. The plating layer has an average current density in the range of 12 to 13 A / dm ² for 9 to 10 minutes at the beginning of the electroplating start, and after that, the average current density is plated in the range of 4 to 5 A / dm ² until the end of the electroplating. It is characterized by one.

When the Ni-P plating layer is formed on the surface of the nickel plating layer by an electroplating method, the Ni-P alloy which is in contact with the nickel plating layer with an average current density in the range of 12 to 13 A / dm ² for 9 to 10 minutes from the start of electroplating. The P content of the plating layer is lowered to improve adhesion with the underlying nickel plating layer, and in the latter case of Ni-P alloy plating, the average current density is plated in the range of 4 to 5 A / dm ^{2 so that} the surface of the electrodeposited grindstone is formed in the Ni-P plating layer. And abrasion resistance of the surface layer portion is improved by increasing the P content of the portion close to the surface portion and increasing the hardness.

Since the Ni-P plating layer having a higher hardness and higher wear resistance than the nickel plating is deposited on the surface of the nickel plating layer, premature wear of the plating layer is prevented during grinding of the mobile phone glass, and as a result, premature dropping of the diamond particles is prevented. Tool life is increased. In addition, since the Ni-P plating layer deposited on the surface of the nickel plating layer has better non-tackiness to the cutting chips than the nickel plating layer, the cutting chips are less likely to adhere to the surface between the diamond particles, thereby improving the grinding property.

The plating layer of the electrodeposited diamond grindstone used in the present invention is formed of two layers, both of which are performed by electroplating, and because the heat treatment is not necessary, the process is simple and the manufacturing cost is low, and the lower nickel plating layer and the upper layer are Adhesiveness with Ni-P plating layer is high, and peeling of a lower layer part and an upper layer part does not generate | occur | produce.

In addition, as a plating layer deposited on the surface of the nickel plating layer which is a lower layer, Ni-P alloy is formed in the thickness of 25-30 micrometers by the electroplating method, and the Ni-P plating layer which forms the upper layer of a nickel plating layer is an initial stage of electroplating start. The present invention using the electrodeposited diamond grindstone plated with an average current density in the range of 12 to 13 A / dm ² for 9 to 10 minutes, and after that the average current density in the range of 4 to 5 A / dm ² until the end of electroplating. the grinding conditions, the wheel speed 1100? 1200m / min, the material removal rate ^{70? 130 (mm 3 / min} ? mm), table feed rate 7? 13m / min, the grinding depth range of 9? 11μm. If the grindstone speed is more than 1250m / min, the grinding heat is increased and the grindstone life is shortened. If the grindstone speed is 1050m / min or less, the grinding resistance is increased and the grindstone life is shortened, so the grindstone speed is in the range of 1100 ~ 1200m / min. If the material removal rate is greater than 131 (mm ³ / min? Mm), the grinding resistance is increased and the grinding wheel life is shortened. If the material removal rate is less than 69 (mm ³ / min? Mm), the material removal rate is 70 ~ 130 (mm ^3). / min? mm).

As described above, according to the present invention, when grinding glass for mobile phones using electrodeposited diamond grinding wheels, grinding wheel life is long, processing efficiency is high, cracks on the grinding surface are prevented, and surface roughness is improved.

In the electrodeposition diamond grindstone used in the present invention, in the electrodeposited grindstone in which diamond particles are bonded to a nickel plating layer deposited on the surface of the grindstone main body, a plating layer having better abrasion resistance and non-tackiness than the nickel plating layer is formed on the surface of the nickel plating layer. The electrodeposited layer is formed into two electrodeposition layers by deposition, and as a plating layer deposited on the surface of the nickel plating layer, which is a lower layer, a Ni-P alloy is formed to have a thickness of 25 to 30 μm by electroplating, and the upper layer of the nickel plating layer is formed. The Ni-P plating layer to be formed is plated with an average current density of 9 to 10 minutes at the beginning of electroplating in the range of 12 to 13 A / dm ² , and thereafter an average current density of 4 to 5 A / until the end of electroplating. It is characterized by plating in the range of dm ² .

When the Ni-P plating layer is formed on the surface of the nickel plating layer by an electroplating method, the Ni-P alloy which is in contact with the nickel plating layer with an average current density in the range of 12 to 13 A / dm ² for 9 to 10 minutes from the start of electroplating. The P content of the plating layer is lowered to improve adhesion with the underlying nickel plating layer, and in the latter case of Ni-P alloy plating, the average current density is plated in the range of 4 to 5 A / dm ^{2 so that} the surface of the electrodeposited grindstone is formed in the Ni-P plating layer. And abrasion resistance of the surface layer portion is improved by increasing the P content of the portion close to the surface portion and increasing the hardness.

Since the Ni-P plating layer having a higher hardness and higher wear resistance than the nickel plating is deposited on the surface of the nickel plating layer, premature wear of the plating layer is prevented during grinding of the mobile phone glass, and as a result, premature dropping of the diamond particles is prevented. Tool life is increased. In addition, since the Ni-P plating layer deposited on the surface of the nickel plating layer has better non-tackiness to the cutting chips than the nickel plating layer, the cutting chips are less likely to adhere to the surface between the diamond particles, thereby improving the grinding property.

The plating layer of the electrodeposited diamond grindstone used in the present invention is formed of two layers, both of which are performed by electroplating, and because the heat treatment is not necessary, the process is simple and the manufacturing cost is low, and the lower nickel plating layer and the upper layer are Adhesiveness with Ni-P plating layer is high, and peeling of a lower layer part and an upper layer part does not generate | occur | produce.

In addition, as a plating layer deposited on the surface of the nickel plating layer which is a lower layer, Ni-P alloy is formed in the thickness of 25-30 micrometers by the electroplating method, and the Ni-P plating layer which forms the upper layer of a nickel plating layer is an initial stage of electroplating start. The average current density for 9-10 minutes is in the range of 12-13 A / dm ² , and after that, the average current density is plated in the range of 4-5 A / dm ² until the end of electroplating. Grinding conditions of the present invention using the above-mentioned electrodeposited diamond grindstone, the grinding wheel speed 1100 ~ 1200m / min, material removal rate 70 ~ 130 (mm ³ / min? Mm), table feed speed 7 ~ 13m / min, grinding depth 9 ~ 11μm Range.

Table 1 shows the electrodeposition conditions of Example 1, Example 2, and Comparative Example 1-Comparative Example 4. In Examples 1 and ² , the nickel plating layer was formed to a thickness of 100 μm by energizing the main body surface of the metal grindstone for 3 hours with an average current density of 2.0 A / dm ² by electroplating, followed by forming the nickel plating layer to a thickness of 100 μm. surface was electroplated with Ni-P alloy on the, in the proportion of the electric plating _{liquid, NiSO 4? 6H 2 O 260g} / ℓ, NiCl 2? 6H 2 O 60g / ℓ, using phosphorous acid 10g / ℓ, the temperature of the plating solution Is 65 ℃, the initial pH of plating is 1.3, and current is applied with an average current density of 13A / dm ² for 10 minutes at the beginning of the start of electroplating without performing leggings, and then the average current until the end of electroplating. The density was lowered to 4.5 A / dm ² and energized for 25 minutes to form an electroplated film of Ni-P alloy having a total thickness of 26 μm. Two kinds of diamond particles were used, each having a fracture rate of 28.2 (wt%) and 37.9 (wt%), and the size of the diamond grains was # 80. The grinding | pulverization rate of a grindstone particle measures the weight% after putting into a vibration mill apparatus for 4 minutes after making particle size uniform. In Comparative Examples 1 and 2, the nickel plating of the lower layer was the same as those of Examples 1 and 2, but in Comparative Example 1, the average current density during the initial 10 minutes was 3A when plating the upper Ni-P alloy. a / dm ^2, and is one of an average current density of the later to 8A / dm ^2. In addition, in Comparative Example 2, the average current density for 35 minutes was kept constant at 7 A / dm ² regardless of the initial and the late stages in the plating of the Ni-P alloy as the upper layer. Comparative Examples 3 and 4 are conventional electrodeposited diamond grinding wheels for glass grinding for mobile phones, and are formed of a single layer nickel plated layer, and Comparative Examples 3 and 4 are all other than those having different crushing rates of diamond particles. The conditions were the same, and the single layer plating was performed by energizing for 3.6 hours at an average current density of 2.5 A / dm ² .

It can be seen from Table 1 that the Vickers hardness of the Ni electroplating layer is 120 or more than twice the electroplating layer hardness of the Ni-P alloy under all conditions. When the hardness of the plating layer in Example 1, Example 2, Comparative Example 1 and Comparative Example 2 in which the Ni-P alloy was plated on the upper layer was compared, the Vickers hardness of Example 1 and Example 2 was the highest at 290, Abrasion resistance is the highest.

In addition, since the diamond dropout rate of Example 1 and Example 2 was 0%, the diamond drop rate was significantly improved as compared with the conventional electrodeposited diamond grindstones shown in Comparative Examples 3 and 4.

Table 2 shows the grinding wheel life and grinding initial stage when grinding the glass for mobile phones by using the electrodeposited diamond grindstone of Example 1, Example 2 and Comparative Example 1-Comparative Example 4 of Table 1 at different grinding wheel speeds and material removal rates. The number of cracks of 0.1 mm or more per 30 mm of grinding length at the grinding surface, and the surface roughness of the grinding surface.

As the workpiece, glass for mobile phones having a size of 3.5cm in width, 6cm in length and 1mm in thickness was used. The glass for mobile phones used was Knoop hardness 180kgf / mm and tensile strength 210kgf / cm ² . Grinding method is upward plunge grinding, grinding wheel speed is changed to 800, 1150 and 1500m / min, grinding wheel depth is changed to 10 and 20μm, table feed speed is changed to 8, 12m / min, cutting fluid KS W2 coolant was used. In addition, the dropping rate of the diamond particle compared the falling number of the diamond particle 30 minutes after the start of grinding and 3 hours after the start of grinding. The wear surface of the electrodeposited diamond grindstone was observed with an optical microscope, and the dropping state of the diamond particle was observed.

As shown in Table 2, by forming a plating layer having better wear resistance and non-tackiness than the nickel plating layer on the surface of the nickel plating layer, it is formed as two layers of electrodeposition layers, and Ni-P alloy is used as the plating layer deposited on the surface of the nickel plating layer. The Ni-P plating layer formed to a thickness of 25-30 micrometers by the electroplating method and forming an upper layer of a nickel plating layer has an average current density in the range of 12-13 A / dm <^2> for 9-10 minutes at the beginning of electroplating start, Electrodeposited diamond whetstone plated in the average current density in the range of 4-5 A / dm ² exhibits excellent performance.

1 is a cross-sectional view of the electrodeposition whetstone of the present invention.

FIG. 2 is a micrograph showing the wear state of electrodeposited diamond particles when the electrodeposited diamond grindstone of Example 1 was ground at a grinding wheel speed (1150 m / min) and a material removal rate of 120 (mm ³ / min · mm)

FIG. 3 shows the wear state of the electrodeposited diamond grains when the electrodeposited diamond grindstone of Example 1 was ground at a grinding wheel speed (1150 m / min) and a material removal rate of 120 (mm ³ / min · mm). A magnified micrograph

Figure 4 is a micrograph showing the wear state of the electrodeposited diamond grains when grinding at the grinding wheel speed (1150m / min), material removal rate 120 (mm ³ / min? Mm) using the electrodeposited diamond grindstone of Example 2

FIG. 5 shows the wear state of the electrodeposited diamond grains when the electrodeposited diamond grindstone of Example 1 was ground at a grinding wheel speed (1150 m / min) and a material removal rate of 120 (mm ³ / min · mm). A magnified micrograph

FIG. 6 is a micrograph showing the wear state of electrodeposited diamond grains when the electrodeposited diamond grindstone of Comparative Example 1 was ground at a grinding wheel speed (1500 m / min) and a material removal rate of 80 (mm ³ / min · mm)

FIG. 7 shows the wear state of the electrodeposited diamond grains when the electrodeposited diamond grindstone of Comparative Example 1 was ground at a grinding wheel speed (1150 m / min) and a material removal rate of 120 (mm ³ / min · mm). A magnified micrograph

FIG. 8 is a micrograph showing the wear state of electrodeposited diamond grains when the electrodeposited diamond grindstone of Comparative Example 2 was ground at a grinding wheel speed (1500 m / min) and a material removal rate of 80 (mm ³ / min · mm)

FIG. 9 shows the wear state of electrodeposited diamond grains when the electrodeposited diamond grindstone of Comparative Example 2 was ground at a grinding wheel speed (1150 m / min) and a material removal rate of 120 (mm ³ / min · mm). A magnified micrograph

FIG. 10 is a micrograph showing the wear state of electrodeposited diamond particles when the electrodeposited diamond grindstone of Comparative Example 3 was ground at a grinding wheel speed (1150 m / min) and a material removal rate of 120 (mm ³ / min · mm).

Fig. 11 is a micrograph showing the state of the grinding surface when grinding at the grinding wheel speed (1150 m / min) and the material removal rate of 80 (mm ³ / min? Mm) using the electrodeposited diamond grinding wheel of Example 1;

12 is a micrograph showing the state of the grinding surface when grinding at the grinding wheel speed (1150 m / min) and the material removal rate 120 (mm ³ / min? Mm) using the electrodeposited diamond grindstone of Example 1;

Fig. 13 is a micrograph showing the state of the grinding surface when grinding at the grinding wheel speed (1500 m / min) and the material removal rate of 80 (mm ³ / min? Mm) using the electrodeposited diamond grinding wheel of Example 2;

Fig. 14 is a micrograph showing the state of the grinding surface when grinding at the grinding wheel speed (1150 m / min) and the material removal rate 120 (mm ³ / min? Mm) using the electrodeposited diamond grinding wheel of Example 2;

Fig. 15 is a micrograph showing the state of the grinding surface when grinding at the grinding wheel speed (1150 m / min) and the material removal rate 120 (mm ³ / min? Mm) using the electrodeposited diamond grinding wheel of Comparative Example 1;

16 is a micrograph showing the state of the grinding surface when grinding at the grinding wheel speed (1150 m / min) and material removal rate 120 (mm ³ / min? Mm) using the electrodeposited diamond grindstone of Comparative Example 2;

Fig. 17 is a micrograph showing the state of the grinding surface when grinding at the grinding wheel speed (1150 m / min) and the material removal rate of 80 (mm ³ / min? Mm) using the electrodeposited diamond grinding wheel of Comparative Example 3;

Fig. 18 is a micrograph showing the state of the grinding surface when grinding at the grinding wheel speed (1500 m / min) and the material removal rate of 80 (mm ³ / min · mm) using the electrodeposited diamond grinding wheel of Comparative Example 3.

[Description of the code]

1: electrodeposited diamond whetstone

2: diamond grain

3: nickel plating layer

4: Ni-P alloy plating layer

5: whetstone body

Claims (1)

In the electrodeposited grindstone in which diamond particles are bonded to the nickel plating layer deposited on the surface of the grinding part of the grindstone body, two layers of electrodeposition layers are formed by depositing a plating layer on the surface of the nickel plating layer that is more wear resistant and non-tacky than the nickel plating layer. As the plating layer deposited on the surface of the nickel plating layer, the Ni-P alloy is formed to have a thickness of 25 to 30 µm by the electroplating method, and the Ni-P plating layer forming the upper layer of the nickel plating layer is 9? Grinding wheel speed 1100-1200m / min, material using electrodeposited diamond grindstone which plated average current density in the range of 12-13 A / dm ² for 10 minutes, and plated the average current density of the latter in the range of 4-5 A / dm ² Method for grinding in the range of removal rate 70 ~ 130 (mm ³ / min? Mm), table feed rate 7 ~ 13m / min, grinding depth 9 ~ 11μm.

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