JP2000288917A - Wrapping device and polishing method using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the uneven abrasion of a fixed abrasive grain pellet by dividing a pellet into a specified number or more of specifications in the radial direction of a surface plate, and setting the difference between maximum value minimum value generated in the surface plate radial direction of the polishing ratio of pellet to workpiece represented by a specified expression smaller than that in a pellet of single specification. SOLUTION: A pellet is divided into two or more specification in the radial direction of a surface plate 1, and the difference between maximum value and minimum value generated in the radial direction of the surface plate of the polishing ratio of pellet to workpiece or polishing ratio = (polishing volume of workpiece)/(abrasive volume of pellet) is set so as to be smaller than that in the sticking of a pellet of single specification. For example, fixed abrasive grain pellets 2a, 2b are stuck to the surface plate 1, and the polishing ratio of the pellet 2a near the rotating center to glass plate is regulated so as to be closer to the polishing ratio of the circumferential pellet 2b. According to this, the uneven abrasion of the surface plate pellet can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for wrapping an article into a thinner article and a grinding method using the same, and more particularly to a method for economically wrapping a glass substrate for a magnetic recording medium from a glass substrate. And a grinding method using the same.

[0002]

2. Description of the Related Art As an apparatus for wrapping a thin plate such as a glass plate, a carrier containing a workpiece is arranged between an upper surface plate and a lower surface plate rotating in opposite directions to each other. Revolve and revolve your career,
A lapping device that wraps both surfaces of the workpiece is well known.

[0003] In a lapping apparatus, fixed abrasive grains called pellets, which are obtained by uniformly dispersing and forming abrasive grains such as diamond in a base material such as metal or resin called a bond, are often used. In the lapping method using fixed abrasive pellets, the probability of individual pellets encountering the work differs for each pellet, and the relative speed with the work changes in the radial direction of the platen, so the wear of the pellets may vary depending on the location. There was a problem of becoming uneven.

[0004] When the so-called uneven wear, in which the amount of pellet wear differs for each individual pellet, occurs, the accuracy of lapping of the workpiece deteriorates, and as a result, it is necessary to correct the uneven wear of the fixed abrasive pellets. . However, not only the production loss due to the repair work occurs, but also expensive abrasive grains are wasted by the repair work, which is a great hindrance to reducing the processing cost.

As a technique for improving uneven wear of pellets,
A method of optimizing the arrangement of the pellets to be attached to the surface plate has been performed. For example, in the method disclosed in JP-A-6-218661, a method is employed in which the arrangement interval of the pellets to be attached to the surface plate is changed in the radial direction to reduce the difference in the amount of pellet wear in the radial direction. I have. But,
Since it is necessary to lower the pellet attachment density in the vicinity of the outer periphery as compared with the vicinity of the rotation center of the surface plate, there is a problem that the pellet attachment density in the entire surface plate is reduced and the processing speed is reduced. .

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a lapping apparatus having characteristics of suppressing uneven wear of fixed abrasive pellets. I have. Another object of the present invention is to provide a method for efficiently and economically grinding a glass sheet using the lapping apparatus.

[0007]

A first aspect of the present invention is to attach a pellet to an upper platen and a lower platen, and to process the pellets on both surfaces of a workpiece in a carrier disposed between the upper and lower platens. In an apparatus for lapping by pressing against a workpiece, the pellet is divided into two or more specifications in the radial direction of the platen, so that the grinding ratio of the pellet with respect to the workpiece in the radial direction of the platen expressed by the following formula (1) is obtained. A lapping apparatus characterized in that the difference between the maximum value and the minimum value is smaller than when a single specification pellet is attached to the upper and lower platens. Grinding ratio = (grinding volume of workpiece) / (pellet abrasion volume) ... (1)

In the first aspect, the difference between the maximum value and the minimum value of the grinding ratio in the radial direction of the platen with respect to the work piece of the pellet affixed to the upper and lower platens is larger than the case where the entire pellet is constituted by a single specification. As a first method of reducing the size, for example, the bonding material for dispersing abrasive grains such as diamond on the inner peripheral side and the outer peripheral side of the platen is made of the same material, and the bonding force between the diamond abrasive grains and the bond material is used. Can be adopted.

In this case, the bond strength can be made different within the same series of known bond materials such as metal bond, resin bond, vitrified bond and the like. For example, near the center of rotation of the surface plate where the amount of pellet wear is large,
The bond strength is adjusted to be stronger than in the vicinity of the outer periphery where the amount of pellet wear is small. This method has a feature that the degree of freedom in selecting a grinding ratio is large, and in the same series bond, even if the strength of the bond material is changed, the influence on the material processing cost of the pellet is small. In this method, the wear resistance of the pellets is adjusted by the difference in the abrasive holding power.

The grinding ratio near the center of rotation of the surface plate is made closer to the grinding ratio of the outer peripheral portion, and the difference between the maximum value and the minimum value of the grinding ratio in the radial direction of the surface plate is determined as compared with the case where the surface plate pellet is constituted by a single specification. A second method for adjusting the bond series to be smaller is to change the above three types of bond series in the vicinity of the rotation center of the platen and at the outer periphery. That is, a method is adopted in which the specifications such as the material, roughness, and degree of concentration of the abrasive grains are the same, the outer peripheral portion is a resin-bonded grindstone, and the inner peripheral portion is a vitrified bond or a metal-bonded grindstone.

This method is characterized in that the processing characteristics such as the surface roughness of the workpiece are largely different between the bonds between the vicinity of the rotation center of the surface plate and the outer periphery, and the grinding ratio can be adjusted within a large range. .

The grinding ratio near the center of rotation of the platen is made closer to the grinding ratio of the outer peripheral portion, and the difference between the maximum value and the minimum value of the grinding ratio in the radial direction of the platen is determined by comparing the platen pellet with a single specification. As a third method of adjusting the particle diameter to be smaller, it is possible to adopt a method in which the concentration of the abrasive grains (the mixing ratio of the abrasive grains and the bonding material) of the pellet near the rotation center of the platen is larger than that on the outer peripheral side. . By increasing the degree of concentration of abrasive grains, the grinding load per abrasive grain is reduced, and the drop of abrasive grains is reduced. This reduces abrasive wear.

The grinding ratio near the center of rotation of the platen is made closer to the grinding ratio of the outer peripheral portion, and the difference between the maximum value and the minimum value of the grinding ratio in the radial direction of the platen is determined by comparing the platen pellet with a single specification. As a fourth method for adjusting the particle size to be smaller, a method in which the grain size of the abrasive grains of the pellet near the center of rotation of the platen is made larger than that on the outer peripheral side can be adopted. As the diameter of the abrasive grains increases, the processing load on the abrasive grains decreases, and the falling off of the abrasive grains decreases, if the grinding conditions such as the processing pressure and the machining allowance are the same. As a result, the amount of pellet wear is reduced. Changing the grain size of the abrasive grains between the center of rotation of the surface plate and the pellet at the outer periphery involves changes in the processing conditions such as the surface roughness of the workpiece, so when the roughness of the processed surface does not matter. It is desirable to adopt.

According to a second aspect of the present invention, in the first aspect of the present invention, the ratio of the maximum value / minimum value of the grinding ratio of the pellets in which the division of the pellets occurs in the radial direction of the platen is 1 to 1.2. It is characterized by.

The maximum value of the grinding ratio is set to the minimum value of 1.2.
It is preferable to select the ratio to be twice or less in order to further reduce uneven wear of the pellet in the radial direction of the platen and to prolong the life of the pellet.

According to a third aspect of the present invention, the upper platen and the lower platen are arranged so that the surfaces of the upper and lower platens to which the pellets are attached face each other, and both surfaces of the workpiece in the carrier disposed between the platens. ,
In the method of grinding a workpiece in which the pellet is pressed against the workpiece and wrapped, the lapping occurs in a radial direction of a platen at a grinding ratio of the pellet with respect to the workpiece by the following formula (1). The difference between the maximum value and the minimum value is such that the pellet is divided into two or more specifications in the radial direction of the platen so as to be smaller than when the pellet is used as a single specification. It is a grinding method. Grinding ratio = (grinding volume of workpiece) / (pellet abrasion volume) ... (1)

According to a fourth aspect of the present invention, there is provided a grinding method according to the third aspect, wherein the maximum grinding ratio of the grinding ratio of the pellet in the radial direction of the platen /
Lapping is performed so that the ratio of the minimum value is 1 to 1.2. It is desirable to divide the maximum and minimum values of the grinding ratio occurring in the radial direction so as to be as close as possible.

The grinding method according to claim 5 is the method according to claim 3 or 4.
In any of the above, the abrasive grains of the divided pellets are diamond abrasive grains, the grinding ratio is the strength of the metal bond material,
It is characterized by being adjusted by the degree of concentration of abrasive grains.

A grinding method according to a sixth aspect is characterized in that, in any one of the third to fifth aspects, the grinding ratio is set to 500 to 10,000.

In a combination of pellets having a grinding ratio of less than 500 (large pellet wear), even if the wear amount is balanced between the vicinity of the rotation center of the platen and the outer peripheral portion of the pellet,
The life of pellets is shortened and replacement frequency increases. In addition, the cost required for the pellets increases, which is not economically preferable. From such a viewpoint, it is preferable that the grinding ratio of the pellet is 500 or more.

On the other hand, the grinding ratio of the pellets is desirably constituted by pellets of 10,000 or less when the workpiece is glass mainly composed of silica. If it exceeds 10,000, it is difficult to change the abrasive grains for maintaining the sharpness of the pellets, and frequent dressing (dressing of the abrasive grains) is required, and the lapping efficiency is reduced. Further, the grinding ratio of the pellet for maintaining the sharpness greatly changes depending on the workpiece. For glass having a soda lime silica composition used for ordinary window glass, the content is preferably set to 10,000 or less.

A grinding method according to a seventh aspect is characterized in that, in any one of the third to sixth aspects, the workpiece is a glass plate. The composition of the glass plate used is not particularly limited. Aluminoborosilicate composition, borosilicate composition, alkali borosilicate composition, alkali-free composition, soda lime silicate composition, etc. can be exemplified. The present invention is a method of grinding a relatively thick glass base plate mass-produced by a manufacturing method such as a downdraw method, a fusion method, a float method, and a molding method to a thickness that is used or a thickness close thereto. It is effective when processing.

In the present invention, when the pellets are divided in the radial direction of the platen, the plate is divided into two or more specifications. In a lapping apparatus having an outer diameter of about 1200 mm and an inner diameter of about 460 mm, Dividing into two types of pellets, near the center of rotation and outer periphery, makes it possible to easily adjust the grinding ratio of the pellets and easily secure the necessary balance for the amount of wear of the pellets at the center of rotation and the outer periphery. Is desirable.

[0024]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. 1 and 2, a large number of disc-shaped pellets 2 are adhered to an upper and lower platen 1 of a lapping device. A carrier 3 containing a workpiece 4 is arranged between the upper and lower platens, and the carrier 3 revolves and rotates on the platen by a sun gear and an internal gear (not shown). The workpiece 4 is wrapped by the pellets 2 by applying pressure to the upper and lower stools rotating in opposite directions.

In one embodiment of the present invention, fixed abrasive pellets 2a and 2b are attached to a surface plate 1 shown in FIG. The pellet 2a is attached to the vicinity of the center of rotation of the platen, and the pellet 2b is attached to the outer periphery. The grinding ratio of the pellet 2a to the glass plate is determined by the specifications such as the type of grindstone, the grindstone grain size, the bond material, and the degree of concentration of the grindstone. At least one
At least one of them is adjusted so as to approach the grinding ratio of the pellet 2b.

When the workpiece is ground by the lapping device, the relative speed of the workpiece on the surface plate is represented by the number of rotations of the surface plate N (rpm) × the distance from the rotation center to the workpiece (m) × It is roughly proportional to π. In the lapping device, as the distance from the center of rotation increases in the radial direction of the surface plate, the relative speed of the pellet with respect to the workpiece increases.

In order to determine the division of the pellet and the specification of the pellet, a preliminary experiment for measuring the grinding ratio of the pellet was performed. Using a small whetstone, it was investigated how the grinding ratio (wear amount) of the pellet changes by changing the relative speed of the pellet to the workpiece. In the example of the present invention, a lapping apparatus having a platen diameter of 1200 mm and an inner diameter of 460 mm was used.

Preliminary Experiment The grinding ratio of the pellets to be attached to the surface plate used in the examples described later was set under the following conditions and examined using another cup-type grinder. In addition, the grinding ratio of the pellet as follows,
The grinding volume of the workpiece (glass plate) per unit wear amount (volume) of the grindstone was defined by the above equation (1).

Preliminary test conditions: cup-shaped grindstone with an outer diameter of 60 mm and grindstone width of 3 mm-Kind and size of grindstone: diamond abrasive # 200-Grindstone specification A: ML517 metal bond type, manufactured by Mitsubishi Materials Corporation, concentration level 50 B: Mitsubishi Material ML517 metal bond type, concentration 75 C: Mitsubishi material ML74 metal bond type, concentration 50 D: Mitsubishi material ML514 metal bond, concentration 50 ・ Wheel speed (m / min): 65, 91, 117, 1
44, 170 Workpiece: float glass plate with soda-lime-silica composition

The results obtained are shown in Table 1. The following can be seen from Table 1. 1) As the peripheral speed of the grindstone increases with any grindstone, the grinding ratio increases. In other words, if the grinding is performed at a small grinding wheel peripheral speed to grind a fixed amount of the glass plate, the abrasion of the grinding wheel increases. 2) Increasing the degree of concentration of abrasive grains on the grindstone increases the grinding ratio. When grinding a certain amount of glass plate at the same peripheral speed, the wear amount of the grindstone can be reduced by increasing the degree of concentration of the abrasive grains of the grindstone.

(Example) Based on the knowledge obtained in the preliminary experiment, the specification of the platen pellet of the lapping device was divided into two in the radial direction of the platen as shown in FIG. The type of grindstone (bond type, degree of concentration) was selected for the outer peripheral portion, and a glass disk having a diameter of 63.5 mm and a thickness of 1.1 mm was lapped to a thickness of 0.8 mm. The lapping conditions are as follows. (Lapping conditions)-Lapping machine: 18B-Plate: outer diameter φ1200 mm, inner diameter φ460 mm-Platen rotation speed: 45 rpm-Number of pellets: 1800-Inner periphery of platen: From inner circumference (φ460 mm) of platen to φ560 mm Outer surface of platen: φ560mm to φ1200mm

A pellet of grinding stone type D is stuck near the center of rotation of the platen. A pellet of grinding stone type B is attached to the outer periphery of the surface plate. As can be seen from Table 1, the maximum value of the grinding ratio of the pellets attached to the surface plate is 3600, and the minimum value is 310.
0. The ratio is 1.16. About 10,000 sheets (about 9
FIG. 4 shows the results of measuring the difference in wear (flatness) of the pellets on the surface plate after lapping of 000 cm ³ ). The height difference of the pellet surface was about 5 μm.

Comparative Example A lapping process was performed on a glass plate in the same manner as in the example, except that the pellets had a single structure of the grindstone B shown in Table 1. The maximum value of the grinding ratio of the pellets attached to the surface plate was 3600, and the minimum value was 2700.
It is. The ratio is 1.33. FIG. 5 shows the results of measuring the difference (flatness) in the amount of wear of the platen pellets when about 10,000 glass plates were wrapped. The height difference of the pellet surface was about 11 μm.

From the above results, it can be seen that when the entire surface plate pellet is made of a uniform grindstone type as in the comparative example, the wear of the pellet is greater near the center of rotation of the surface plate than at the outer peripheral portion. On the other hand, as shown in the examples, when the specifications of the pellets are divided in the radial direction of the platen so that the ratio of the maximum value of the grinding ratio of the grinding stone to the minimum value approaches 1, the wear of the pellets is reduced in the radial direction of the platen. It can be seen that it is improved. That is, uneven wear is suppressed.

In the present invention, when the specification of the pellet is divided into two, it is more preferable to make the maximum value / minimum value of the grinding ratio of the pellet close to 1.

It is preferable to maintain the flatness of the pellets as much as possible after lapping a large number of glass plates, especially when using an expensive diamond grindstone, because the life of the pellets can be extended.

[0037]

[Table 1] ================================== Kind of grinding wheel---------- −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− Distance from the center of rotation (mm) 230 320 415 510 600 −−−−−−−−−−−−−−− ------------------------------------------------------------------------------------------------------------------ A 1700 1900 2000 2200 2400 B 2700 3100 3200 3400 3600 C 19000 21600 22000 23600 24300 D 3400 3800 4100 4200 4500 == ========================= =======

[0038]

The lapping device of the present invention divides the pellet into two or more specifications in the radial direction of the platen, and determines the difference between the maximum value and the minimum value of the grinding ratio generated in the radial direction of the platen using a single specification for the pellet. Because it was made smaller than when configured with
Uneven wear of the platen pellet is suppressed.

Thus, the frequency of truing for correcting the surface shape of the surface plate pellet can be greatly reduced, and the processing efficiency is improved. In addition, since uneven wear of the pellets is suppressed, a margin for correcting the pellets by truing can be reduced, and the cost of the grinding wheel can be reduced.

In the method of grinding a glass sheet by the lapping apparatus of the present invention, the pellets are divided into two or more specifications by a platen radius method, and uneven wear of the platen pellets is suppressed. Processing accuracy when performing is stabilized.

By dividing the specifications of the pellets in the radial direction of the platen so that the maximum value of the grinding ratio generated in the radial direction of the surface plate becomes 1 to 1.2 times the minimum value, uneven wear of the pellets of the surface plate can be suppressed. In addition, the life of the platen pellet can be prolonged.

Further, the grinding ratio of the grindstone is set to 500 to 10,000.
When the glass sheet is ground in a combination selected within the range of 00, the sharpness can be maintained by performing the sharpening operation of the grindstone.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of a wrapping device according to the present invention.

FIG. 2 is a layout view of a platen, a carrier, and a workpiece of the lapping device of the present invention.

FIG. 3 is a diagram illustrating an arrangement state of pellets in the wrapping device of the present invention.

FIG. 4 is a diagram illustrating a flatness measurement of a pellet surface after a lapping process in an example.

FIG. 5 is a measurement diagram of flatness of a pellet surface after lapping processing of a comparative example.

[Explanation of symbols]

 1: Upper and lower platen 2: Pellet 2a: Pellet inner peripheral pellet 2b: Pellet outer peripheral pellet 3: Carrier 4: Workpiece 5: Rotating shaft

Continued on the front page F term (reference) 3C058 AA04 AA09 AA14 AA18 AB04 AB08 BA02 BA09 CA01 CB03 CB10 DA06 DA09 3C063 AA01 AB05 BA03 BB02 BC02 EE15

Claims (7)

[Claims] Claims 1. A pellet is stuck on an upper platen and a lower platen,
In an apparatus that wraps both surfaces of a workpiece in a carrier disposed between the upper and lower platens by pressing the pellets against the workpiece, dividing the pellets into two or more specifications in a radial direction of the platen. Thus, the difference between the maximum value and the minimum value generated in the radial direction of the platen of the grinding ratio of the above-mentioned pellet with respect to the workpiece shown by the following formula (1) is larger than when a single specification pellet is stuck on the upper and lower platens. A wrapping device characterized in that the wrapping device is also made smaller. Grinding ratio = (grinding volume of workpiece) / (pellet abrasion volume) ... (1) 2. The method according to claim 1, wherein the division of the pellets is performed such that the ratio of the maximum value / minimum value of the grinding ratio in the radial direction of the platen is 1 to 1.2.
The wrapping device according to claim 1, wherein 3. An upper platen and a lower platen are arranged such that the surfaces of the upper and lower platens on which the pellets are adhered face each other. In the method of grinding a workpiece in which lapping is performed by pressing the workpiece against the workpiece, a maximum value of the lapping generated in the radial direction of the platen at a grinding ratio of the pellet with respect to the workpiece by the following formula (1): And the difference between the minimum value is smaller than when the pellets are a single specification,
A grinding method for a workpiece, wherein the workpiece is divided into two or more specifications in a radial direction of a surface plate. Grinding ratio = (grinding volume of workpiece) / (pellet abrasion volume) ... (1) 4. The grinding method for a workpiece according to claim 3, wherein a ratio of a maximum value / minimum value of the grinding ratio generated in a radial direction of the platen is 1 to 1.2. . 5. The method according to claim 3, wherein the divided pellets are diamond abrasive grains, and the grinding ratio is adjusted by the strength of the metal bond material and the degree of concentration of the abrasive grains.
2. The method for grinding a workpiece according to claim 1. 6. The grinding method for a workpiece according to claim 3, wherein the grinding ratio is set to 500 to 10,000. 7. The grinding method according to claim 3, wherein the workpiece is a glass plate.