Field of the Invention
The present invention relates to a grinding wheel for grinding a workpiece such as a resin substrate and also to a grinding method using the grinding wheel.
Description of the Related Art
Usually, a tough material such as resin and metal is subjected to cutting such as flattening and thinning in a tool cutting apparatus (see Japanese Patent Laid-open No. 2000-173954, for example). The tool cutting apparatus described in Japanese Patent Laid-open No. 2000-173954 includes a spindle adapted to be rotated about a vertical axis, a mount fixed to the lower end of the spindle, a wheel base mounted on the lower surface of the mount, and a cutting tool such as a diamond tool and a cemented carbide tool fixed to a part of the lower surface of the wheel base at an outer circumferential portion thereof, wherein the wheel base and the cutting tool constitute a grinding wheel. Accordingly, the cutting tool having an acute cutting edge is rotated about the axis of the spindle to cut the upper surface of a workpiece formed of a tough material held on a chuck table, thereby flattening or thinning the workpiece.
In the grinding wheel of the tool cutting apparatus described in Japanese Patent Laid-open No. 2000-173954, the shape of the acute cutting edge of the cutting tool is gradually changed with an increase in number of workpieces, causing a degradation in grinding quality. Accordingly, the shape of the cutting tool must be corrected periodically. However, special processing such as electrical discharge processing is required for the shape correction of the cutting tool such as a diamond tool and a cemented carbide tool, so that there is a problem such that any separate equipment dedicated to the shape correction is required and much time is also required for the shape correction.
It is therefore an object of the present invention to provide a grinding wheel and a grinding method which can correct the shape of an abrasive member used as a cutting edge easily in a short period of time.
In accordance with an aspect of the present invention, there is provided a grinding wheel for grinding a resin substrate, including a wheel base having a free end portion and a fixed portion to be fixed to a spindle; and a plurality of abrasive members fixed to the free end portion of the wheel base; the wheel base having a plurality of grinding water supply holes for supplying a grinding water to the abrasive members; each abrasive member being formed as a segment abrasive obtained by binding diamond abrasive grains with a metal bond; the shape of each abrasive member being set so that each abrasive member has an outer surface extending downward from the free end portion of the wheel base so as to be inclined radially outward of the wheel base; the plurality of abrasive members being arranged annularly at given intervals; the plurality of grinding water supply holes being formed on the free end portion of the wheel base in the vicinity of the abrasive members so as to each correspond to the abrasive members in the condition where each grinding water supply hole lies on a line connecting the corresponding abrasive member and the axis of rotation of the wheel base.
With this configuration, the angle formed by the outer surface of each abrasive member with respect to the upper surface (work surface) of the resin substrate is set as an acute angle, so that each abrasive member is used like a cutting edge. The inclined outer surface of each abrasive member acts on the resin substrate in grinding the resin substrate, so that the resin substrate can be well thinned. At this time, the resin substrate is continuously ground by using the plural abrasive members, so that a fine grinding dust is produced and it does not deposited in a grinding apparatus, thereby avoiding drainage trouble. Further, even when the shape of each abrasive member becomes worse during grinding, the shape of each abrasive member can be corrected by a dresser board. Accordingly, it is not necessary to newly provide any equipment for shape correction of each abrasive member, but the shape of each abrasive member can be easily corrected in a short period of time, thereby attaining good economy. Further, since a grinding water is supplied from the plural grinding water supply holes to the plural abrasive members each corresponding thereto, a frictional heat generated from each abrasive member during grinding can be effectively removed.
In accordance with another aspect of the present invention, there is provided a grinding method of grinding a tough substrate by using a grinding apparatus including a chuck table for holding the tough substrate, grinding means having a rotating spindle and a grinding wheel fixed to the rotating spindle for grinding the tough substrate held on the chuck table, abrasive feeding means for relatively moving the grinding means and the chuck table toward and away from each other in an abrasive feeding direction, and moving means for relatively moving the grinding means and the chuck table in a radial direction of the chuck table; the grinding wheel including a wheel base having a free end portion and a fixed portion fixed to the rotating spindle; and a plurality of abrasive members fixed to the free end portion of the wheel base; the wheel base having a plurality of grinding water supply holes for supplying a grinding water to the abrasive members; each abrasive member being formed as a segment abrasive obtained by binding diamond abrasive grains with a metal bond; the shape of each abrasive member being set so that each abrasive member has an outer surface extending downward from the free end portion of the wheel base so as to be inclined radially outward of the wheel base; the plurality of abrasive members being arranged annularly at given intervals; the plurality of grinding water supply holes being formed on the free end portion of the wheel base in the vicinity of the abrasive members so as to each correspond to the abrasive members in the condition where each grinding water supply hole lies on a line connecting the corresponding abrasive member and the axis of rotation of the wheel base; the grinding method including grinding the tough substrate held on the chuck table by creep feed grinding such that the grinding wheel being rotated is horizontally moved relative to the tough substrate.
With this configuration, the tough substrate is ground by the plural abrasive members each having the inclined outer surface, so that a large grinding dust is not produced in grinding the tough substrate, so that the tough substrate can be well thinned. Further, when the shape of each abrasive member is changed during grinding the tough substrate, the shape of each abrasive member can be easily corrected in a short period of time. Further, since a grinding water is supplied from the plural grinding water supply holes to the plural abrasive members, a frictional heat generated from each abrasive member can be effectively removed.
The above and other objects, features and advantages of the present invention and the manner of realizing them will become more apparent, and the invention itself will best be understood from a study of the following description and appended claims with reference to the attached drawings showing a preferred embodiment of the invention.
A grinding apparatus according to a preferred embodiment of the present invention will now be described with reference to the attached drawings.
As shown in
The grinding apparatus 1 includes a base housing 10 having an upper surface. The upper surface of the base housing 10 is formed with a rectangular opening extending in the X direction. This rectangular opening is closed by a movable plate 16 and a bellows-like waterproof cover 17, wherein the movable plate 16 is movable with the chuck table 15 in the X direction, and the waterproof cover 17 is mounted on opposite sides of the movable plate 16 in the X direction so as to be expanded and contracted in the X direction by the movement of the movable plate 16. Ball screw type moving means 20 for moving the chuck table 15 in its radial direction (X direction) is provided below the waterproof cover 17. The chuck table 15 has an upper surface as a holding surface 18 for holding the resin substrate W under suction. The holding surface 18 is formed of a porous material. The holding surface 18 is connected through a suction passage (not shown) formed in the chuck table 15 to a vacuum source (not shown), so that a vacuum is produced on the holding surface 18 to thereby hold the resin substrate W on the holding surface 18 under suction.
A vertically extending column 11 is provided on the base housing 10 at its rear portion. Abrasive feeding means 25 is provided on the front side of the column 11. The abrasive feeding means 25 functions to move grinding means 30 toward and away from the chuck table 15 in an abrasive feeding direction (Z direction shown by an arrow Z in
The grinding means 30 includes a housing 31 mounted on the front surface of the Z table 27, a cylindrical spindle 32 rotatably supported through a flange 34 to the housing 31, and a mount 33 fixed to the lower end of the spindle 32. The grinding means 30 further includes the grinding wheel 40 mounted on the lower surface of the mount 33. The grinding wheel 40 includes the plurality of abrasive members 50 arranged annularly at given intervals. Each abrasive member 50 is a segment abrasive formed by binding diamond abrasive grains with a metal bond. The detailed configuration of the grinding wheel 40 and the abrasive members 50 will be hereinafter described.
As shown in
In general, the resin substrate W formed of a tough material is preferably cut by a cutting tool such as a diamond tool and a cemented carbide tool. However, when the cutting tool is worn, much time and dedicated equipment are required for shape correction of the cutting tool. To cope with this problem, each abrasive member 50 of the grinding wheel 40 according to this preferred embodiment has a cutting edge like a cutting tool, thereby facilitating the thinning of the resin substrate W by the abrasive members 50. Further, in the case that the abrasive members 50 are worn, the dresser board D (see
In the case of cutting the resin substrate W by using a single cutting tool in a conventional tool cutting apparatus, the resin substrate W is cut by the single cutting tool fixed to the lower surface of a mount, so that a cutting dust becomes a sheet-like dust to cause a possibility of drainage trouble. To cope with this problem, the grinding wheel 40 according to this preferred embodiment has the plural abrasive members 50 to thereby continuously grind the resin substrate W, so that a powder-like grinding dust can be produced. Further, the grinding wheel 40 according to this preferred embodiment includes a plurality of grinding water supply holes 46 (see
The grinding wheel 40 according to this preferred embodiment will now be described in more detail with reference to
As shown in
As described above, each abrasive member 50 is formed by binding (sintering) diamond abrasive grains with a metal bond. Each abrasive member 50 thus formed has a high hardness, so that even when each abrasive member 50 is used like a cutting tool in grinding the resin substrate W, the shape of each abrasive member 50 can be easily maintained. Further, like general abrasive members of a grinding wheel, the shape of each abrasive member 50 can be corrected by using the dresser board D (see
As shown in
The wheel base 41 has a radially inside lower surface 45 and a radially outside lower surface 47. The plural grinding water supply holes 46 are formed on the radially inside lower surface 45 of the wheel base 41 so as to be positioned in the vicinity of the plural abrasive members 50 in such a manner that each grinding water supply hole 46 lies on a line L connecting the corresponding abrasive member 50 and the axis of rotation of the grinding wheel 40. More specifically, P1 shown in
In contrast, the grinding wheel 60 as a comparison shown in
If the resin substrate W continues to be ground by using the grinding wheel 60 as a comparison, a part of the resin substrate W may be melted by the frictional heat generated in grinding and a resultant melted resin 69 may stick to the abrasive members 68. In this case, the melted resin 69 sticking to the abrasive members 68 has an adverse effect in grinding the resin substrate W, causing a degradation in appearance of the resin substrate W after grinding. In this manner, even when the width 63 of each abrasive member 68 is small in the case of grinding the resin substrate W by using the increased number of abrasive members 68, the abrasive members 68 cannot be enough cooled by the grinding water in the arrangement that each grinding water supply hole 66 does not lie on the line L connecting each abrasive member 68 and the axis of rotation of the grinding wheel 60 as shown in
The present inventor tested to modify the grinding wheel 40 in such a manner that the grinding water supply holes 46 each correspond to alternate ones of the plural abrasive members 50. When the resin substrate W was ground by using such a modified grinding wheel 40, the adhesion of a melted resin to the abrasive members 50 was not observed. This is considered to be due to the fact that the grinding water supplied from each grinding water supply hole 46 strikes the corresponding abrasive member 50 and then changes the flow direction of the grinding water toward the next abrasive member 50 adjacent to the above corresponding abrasive member 50. Accordingly, the plural grinding water supply holes 46 are not each necessarily required to correspond to the plural abrasive members 50, provided that each grinding water supply hole 46 is so formed in the vicinity of the abrasive members 50 as to lie on the line L connecting the corresponding abrasive member 50 and the axis of rotation of the grinding wheel 40.
A grinding operation using the grinding wheel 40 according to this preferred embodiment will now be described with reference to
As shown in
Since the outer surface 54 of each abrasive member 50 is inclined as shown in
In contrast, the grinding wheel as a comparison shown in
Further, as also shown at the left position in
According to this preferred embodiment, all of the abrasive members 50 constituting the grinding wheel 40 (see
The grinding dust of the resin substrate W will now be described. As shown in
The grinding operation and the dressing operation according to this preferred embodiment will now be described with reference to
As shown in
At this time, as shown in
As shown in
As shown in
(Test)
The following test was conducted in such a manner that a workpiece to be evaluated was ground by using the grinding wheel 40 having the abrasive members 50 in the condition where the width of each abrasive member 50 was changed and the number of abrasive members 50 was also changed. Then, the condition of the ground surface of the workpiece was checked. The width of each abrasive member 50 and the number of abrasive members 50 were changed so that the contact area of all the abrasive members 50 to the workpiece was constant. The grinding wheel 40 was prepared by mounting a plurality of metal bond abrasive members 50 having the same grain size on the wheel base 41 having a wheel diameter of 200 mm. As the workpiece to be evaluated, a resin substrate having a size of 130×130 mm was used. The following grinding conditions were set.
Rotational speed of the spindle: 6000 rpm
Work feed speed: 10 mm/second
Number of workpieces: 10
The results of this test were shown in Table below.
In Test No. 1, only the outer surface of each abrasive member contributes to grinding and a slightly rough ground surface was observed on the resin substrate. In Test No. 9, a grinding force is lacking and a rough ground surface was observed on the resin substrate. In Test Nos. 2 to 8, good ground surfaces were observed on the resin substrates. Accordingly, the width of each abrasive member is preferably set to 3 mm to 8 mm, and more preferably 4 mm to 6 mm. In other words, as shown in
As described above, the grinding wheel 40 according to this preferred embodiment includes the plural abrasive members 50, wherein the angle formed by the outer surface 54 with respect to the upper surface (work surface) of the resin substrate W is set as an acute angle, so that each abrasive member 50 is used like a cutting edge. The inclined outer surface 54 of each abrasive member 50 acts on the resin substrate W to grind it, thereby allowing good thinning of the resin substrate W. At this time, the resin substrate W is continuously ground by the plural abrasive members 50, so that the grinding dust becomes fine and the grinding apparatus is therefore not clogged with the grinding dust, thus avoiding drainage trouble. Further, even when the shape of each abrasive member 50 becomes worse during grinding, it can be corrected by the dresser board D. Accordingly, it is not necessary to newly provide any equipment for shape correction of each abrasive member 50, but the shape of each abrasive member 50 can be easily corrected in a short period of time, thereby attaining good economy. Further, since a grinding water is supplied from the plural grinding water supply holes 46 to the plural abrasive members 50 each corresponding thereto, a frictional heat generated from each abrasive member 50 during grinding can be effectively removed.
The present invention is not limited to the above preferred embodiment, but various modifications may be made. In the above preferred embodiment, the size, shape, etc. shown in the attached drawings are merely illustrative and they may be suitably changed within the scope where the effect of the present invention can be exhibited. Further, various modifications may be made without departing from the scope of the object of the present invention.
For example, while each abrasive member 50 is formed as a segment abrasive having a parallelogram shape as viewed in side elevation in the above preferred embodiment, the shape of each abrasive member 50 is not limited. That is, it is only necessary that each abrasive member 50 has the outer surface 54 extending downward from the free end portion 43 of the wheel base 41 so as to be inclined radially outward. For example, each abrasive member 50 may be formed as a segment abrasive having a trapezoidal shape as viewed in side elevation.
Further, while the abrasive feeding means 25 is so configured as to move the grinding means 30 relative to the chuck table 15 toward and away from the chuck table 15 in the abrasive feeding direction (Z direction) in the above preferred embodiment, the configuration of the abrasive feeding means 25 is not limited. That is, it is only necessary that the abrasive feeding means 25 functions to relatively move the grinding means 30 and the chuck table 15 in the abrasive feeding direction. For example, the abrasive feeding means 25 may be configured so as to move the chuck table 15 relative to the grinding means 30 toward and away from the grinding means 30 in the abrasive feeding direction.
Further, while the moving means 20 is so configured as to move the chuck table 15 in its radial direction relative to the grinding means 30 in the above preferred embodiment, the configuration of the moving means 20 is not limited. That is, it is only necessary that the moving means 20 functions to relatively move the grinding means 30 and the chuck table 15 in the radial direction of the chuck table 15. For example, the moving means 20 may be configured so as to move the grinding means 30 relative to the chuck table 15 in its radial direction.
Further, while the grinding wheel 40 is so configured as to be used for creep feed grinding in the above preferred embodiment, the configuration of the grinding wheel 40 is not limited. For example, the grinding wheel 40 may be configured so as to be used for in-feed grinding.
As described above, the present invention has an effect that the shape of each abrasive member to be used as a cutting edge can be easily corrected in a short period of time. In particular, the present invention is useful for a grinding method of grinding a workpiece formed of a tough material such as resin and metal.
The present invention is not limited to the details of the above described preferred embodiment. The scope of the invention is defined by the appended claims and all changes and modifications as fall within the equivalence of the scope of the claims are therefore to be embraced by the invention.
Number | Date | Country | Kind |
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2015-183865 | Sep 2015 | JP | national |
Number | Name | Date | Kind |
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1611352 | Larsson | Dec 1926 | A |
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3181281 | Hensley | May 1965 | A |
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20120142260 | Gosamo | Jun 2012 | A1 |
20160256982 | Mejean | Sep 2016 | A1 |
Number | Date | Country |
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2000-173954 | Jun 2000 | JP |
Number | Date | Country | |
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20170080547 A1 | Mar 2017 | US |