Background Art In general, a grinding stone of q wheel grinder for grinding an object can hardly have the center of mass exactly accorded with the center of rotation. Thus, the operation of the grinding stone may not be precisely performed and the life of the wheel grinder having grinding stone may be decreased due to the abrasion occurred the vibration of the spindle installed in the wheel grinder.

To overcome the above-mentioned problem, the balancing operation should be performed concerning the grinding stone before the grinding stone is installed in the wheel grinder. The balance of the grinding stone is generally adjusted by using a balancing device and such balancing device and adjusting process are disclosed as shown in Figs. 1 to 2D.

Fig. 1 is a perspective view for showing the conventional balancing device for

the wheel grinder.

Referring to Fig. 1, the conventional balancing device has a base 10, two beams 12 erectly prolonged from the base 10, and two parallel cylindrical rods 14 respectively supported by the beams 12. Also, a horizontal gage 16 for measuring the flatness of the wheel grinder is provided at front portion of the base 10.

At that time, a grinding stone 18 is combined with a flange 20 for the grinding stone 18 and a spindle 22 of the flange 20 is supported by means of the cylindrical rods 12.

Meanwhile, a ring-shaped weight groove 24 is formed between one face of the flange 20 and the spindle 22 so as to receive a weight for balancing the grinding stone 18.

Figs. 2A to 2D are side views for illustrating methods for adjusting the balance of the wheel grinder by using the conventional balancing device.

When the balance of the grinding stone 18 is adjusted by using the balancing device, the balancing process is performed according as the grinding stone 18 is moved in the forward and the backward directions while the spindle 22 of the flange 20 is disposed on the cylindrical rod 14.

When the grinding stone 18 is stopped on the cylindrical rod 14, a first wedge- shaped mark 26-1 is added to a peripheral portion of the grinding stone 18 as shown in Fig. 2A.

Then, a first weight 28-1 symmetrically disposed concerning the first wedge- shaped mark 26-1 is attached in the weight groove 24 as shown in Fig. 2B.

Subsequently, when the grinding stone 18 is stopped, the grinding stone 18 is fixed and a second wedge-shaped mark 26-2 is added to a peripheral portion of the 5 grinding stone 18 after the grinding stone 18 rotates again as shown in Fig. 2C. Two second weights 28-2 are respectively attached at portions of the weight groove 24 where the second wedge-shaped mark 26-2 and a prolonged line from the spindle 22 are positioned. In this case, the second weights 28-2 are disposed by the same angle A concerning the first weight 28-1.

10 Then, the grinding stone 18 is set free. At that time, the grinding stone 18 maintains the fixed state when the grinding the balance of the grinding stone 18 is adjusted by the first and the second weights 28-1 and 28-2. Otherwise, the grinding stone 18 rotates again when the balance of the grinding stone 18 does not adjusted. In such case, after the grinding stone 18 is returned to the position in Fig. 2C, the second 15 weights 28-2 are moved in the direction opposed to the rotating direction of the grinding stone 18. By repeating such process, the balance of the grinding stone 18 is accomplished when the grinding stone 18 does not rotate any more as shown in Fig. 2D.

In this case, the angles B, C and D among the weights 28-1 and 28-2 become different from one after another, thereby adjusting the balance of the grinding stone 18.

20 As for the conventional balancing apparatus, however, the balancing process

demands much time and the balance of the grinding stone may not be precisely adjusted.

In addition, an additional device for the balancing process such as a level gage is needed for adjusting the balance of the grinding stone.

Also, since the worn grinding stone is sharpened by means of a dresser after the grinding stone is worn for grinding the object, the grinding stone demands new balancing process so as to grind the object. Hence, the precision of grinding operation may be decreased and the grinding stone has more load during the grinding operation because new balancing process may be omitted considering the time and cost after the dressing process in the field.

Disclosure of the Invention The present invention is intended to overcome the above-described disadvantages. Therefore, it is an object of the present invention to provide a wheel grinder accomplishing rapidly precise adjustment of a balance of a grinding stone without an additional balancing device for the balance of the grinding stone.

It is another object of the present invention to provide a balancing apparatus for a wheel grinder automatically adjusting a balance of a grinding stone during a rotation of the grinding stone.

To accomplish the objects of the present invention according to one aspect of the present invention, there is provided a wheel grinder having a main body, a spindle rotatably installed on the main body and a grinding stone installed on the main body through the spindle.

According to preferred embodiments of the present invention, the wheel grinder comprises a balancing apparatus for supporting the grinding stone and adjusting a 5 balance of the grinding stone wherein the balancing apparatus is disposed on a side of the grinding stone, and a fixing member for fixing the grinding stone to the spindle with the balancing apparatus.

In one preferred embodiment of the present invention, the balancing apparatus has a flange for the grinding stone having a ring-shaped groove formed on one side of 10 the flange, at least one weight member received in the weight groove of the flange, and a cover for covering the weight groove of the flange. A fluid such as oil is filled in the weight groove having a rectangular-shaped cross section.

Preferably, a guiding groove having a semicircular shape is formed on a bottom of the weight groove and a semicircular groove is formed on a bottom of the cover so 15 that the weight groove has a circular-shaped cross section by combining the guiding groove with the semicircular groove. Meanwhile, a bottom of the weight groove is inclined and a bottom of the cover is inclined opposed to the bottom of the weight groove so that the weight groove has a triangular-shaped cross section by combining the bottom of the cover with an inside of the weight groove.

20 In addition, the weight member has a ball shape or an arch shape having a curvature identical to a circumference of the weight groove.

According to another preferred embodiment of the present invention the balancing apparatus has a flange for the grinding stone having a ring-shaped weight groove formed on one side thereof, a weight housing formed on the weight groove of 5 the flange, at least one weight member received in the weight housing, and a cover for covering the weight housing.

Also, according to still another preferred embodiment of the present invention the balancing apparatus has a flange for the grinding stone having one side for supporting one side of the grinding stone, a ring-shaped weight tube attached to the 10 other side of the flange, and at least one weight member received in the weight tube. A fluid such as oil is filled in the weight tube.

To accomplish the objects of the present invention according to another aspect of the present invention, there is provided a wheel grinder having a main body, a spindle rotatably installed on the main body and a grinding stone installed on the main body 15 through the spindle, which comprises two balancing apparatuses for supporting the grinding stone and adjusting a balance of the grinding stone wherein the balancing apparatuses are respectively disposed on both side of the grinding stone, and a fixing member for fixing the grinding stone to the spindle with the balancing apparatuses.

Furthermore, to accomplish the objects of the present invention according to 20 still another preferred embodiment of the present invention, there is provided a balancing apparatus for a wheel grinder having a grinding stone rotating at a predetermined speed by a spindle, which comprises a flange for supporting one side of the grinding stone wherein the flange has a ring-shaped weight groove formed on one side thereof, at least one weight member received in the weight groove, and a cover for 5 covering the weight groove. In this case, a fluid such as oil is filled in the weight groove.

The weight groove preferably has a rectangular-shaped cross section and the weight member has a ball shape or an arch shape having a curvature identical to a circumference of the weight groove.

In the still another preferred embodiment of the present invention, the balancing 10 apparatus for a wheel grinder includes a flange for supporting one side of the grinding stone wherein the flange has a ring-shaped weight groove formed on one side of the flange, a weight housing formed on the weight groove, at least one weight member received in the weight housing, and a cover for covering the weight housing.

Also, according to the still another preferred embodiment of the present 15 invention, the balancing apparatus for a wheel grinder includes a flange for supporting one side of the grinding stone at one side, a ring-shaped weight tube attached to the other side of the flange, and at least one weight member received in the weight tube.

As it is described above, the balancing apparatus for the grinding stone automatically adjusts the balance of the grinding stone when the grinding stone rotates 20 at high speed. Therefore, the time demanded for adjusting the balance of the grinding

stone becomes shorter.

Also, the balance of the grinding stone can be automatically adjusted during the rotation of the grinding stone, so separate balancing process dose not demanded after the dressing process due to the abrasion of the grinding stone.

Brief Description of the Drawings The above objects and other advantages of the present invention will become more apparent by detailed describing preferred embodiments thereof with reference to the attached drawings in which: Fig. 1 is a perspective view for showing the conventional balancing apparatus for the wheel grinder; Figs. 2A to 2D are side views for illustrating methods for adjusting the balance of the wheel grinder by using the conventional balancing apparatus; Fig. 3 is a front view for illustrating a head of a wheel grinder having a balancing apparatus according to the present invention; Fig. 4 is a cross-sectional view taken a line of IV-IV in Fig. 3 for illustrating a balancing apparatus according to a first embodiment of the present invention; Fig. 5 is a side view for showing the balancing apparatus in Fig. 4; Figs. 6 and 7 are schematic side views for illustrating positions of a weight ball in the balancing apparatus combined with the wheel grinder to rotate together according

to the first embodiment of the present invention; Fig. 8 is a vertically cross-sectional view for illustrating a balancing apparatus according to a second embodiment of the present invention; Fig. 9 is a vertically cross-sectional view for illustrating a balancing apparatus according to a third embodiment of the present invention; Fig. 10 is a vertically cross-sectional view for illustrating a balancing apparatus according to a fourth embodiment of the present invention; Figs. I1 and 12 are a plane view and a vertically cross-sectional view for respectively showing a balancing apparatus according to a fifth embodiment of the present invention; Figs. 13 and 14 are a plane view and a vertically cross-sectional view for respectively showing a housing for the balancing apparatus according to the fifth embodiment of the present invention; Fig. 15 is a plane view for showing a weight member having a shape of an arch according to a sixth embodiment of the present invention; and Fig. 16 is a front view for illustrating a wheel grinder having a pair of balancing apparatuses according to a seventh embodiment of the present invention.

Best Modes for carrying out the Invention Hereinafter, preferred embodiments of the present invention will be described in

more detail with reference to the accompanying drawings, but it is understood that the present invention should not be limited to the following embodiments.

Fig. 3 is a front view for illustrating a head of a wheel grinder having a balancing apparatus according to the present invention.

Referring to Fig. 3, a wheel grinder 1000 has a main body (not shown) and a spindle 1100 for rotating a grinding stone 120 at high speed. The spindle 1100 is rotatably installed in the main body of the wheel grinder 1000.

A balancing apparatus 1200 is disposed on one side of the grinding stone 120 to automatically adjusting the balance of the grinding stone 120. The balancing apparatus 1200 rotates with the spindle 1100. Also, the balancing apparatus 1200 is disposed on the left side of the grinding stone 120 so that the balancing apparatus 1200 supports one side of the grinding stone 120 as well as adjusts the balance of the grinding stone 120.

A fixing member 1300 for holding the other side of the grinding stone 120 is disposed on the right side of the grinding stone 120. The fixing member 1300 pushes the other side of the grinding stone 120, thereby firmly fastening one side of the grinding stone 120 to the balancing apparatus 1200. The balancing apparatus 1200, the grinding stone 120 and the fixing member 1300 are fastened like a body by means of a connecting member such as a bolt. Such connection among the balancing apparatus 1200, the grinding stone 120 and the fixing member 1300 will be described later.

Meanwhile, a nut is generally used as the fixing member 1300 for fixing the

grinding stone 120.

Hereinafter, various balancing apparatuses according preferred embodiments of the present invention will be described with reference to the accompanying drawings.

Embodiment 1 Fig. 4 is a cross-sectional view taken a line of IV-IV in Fig. 3 for illustrating a balancing apparatus according to a first embodiment of the present invention, and Fig. 5 is a side view for showing the balancing apparatus in Fig. 4.

Referring to Figs. 4 and 5, a balancing apparatus 100 for a wheel grinder of the present embodiment has a flange 104 for a grinding stone 120 including an inner face tightly contacted to an outer face of the grinding stone 120. The flange 104 for the grinding stone 120 also includes a bush 122 inserted in a shaft hole of a fixing member 1300. An axis hole 108 is formed through the bush 122 for receiving a spindle 1100.

The flange 104 for the grinding stone 120, the grinding stone 120 and the fixing member 1300 are tightly connected one after another by a bolt 106 having a sufficient length enough to pass from the balancing apparatus 100 to a portion of the fixing member 1300.

A weight groove 110 having a shape of a ring is formed an outer face of the flange 104 for the grinding stone 120, and at least one weight member 112 is received in the weight groove 110. The weight member 112 preferably has a shape of a ball as shown in Figs. 4 and 5.

Also, a fluid such as oil 114 is filled in the weight groove 110 in order to reduce the vibration and noise generated from the rotation of the weight member 112 having the ball shape at high speed.

5 In the mean time, the weight member 112 having the ball shape is composed of metal, non-metallic material having heavy weight, fluid having large specific weight or the composite thereof. In addition, the number of the weight member 112 having the ball shape can be adjusted within a range selected for optimistically adjusting the balance of the grinding stone 120 according to several experiments of the present 10 embodiment.

The weight groove 110 is covered with a cover 116 having a shape of a ring so as to seal the weight member 112 and the oil 114 received in the weight groove 110 from outside. A sealing member 118 for preventing the leakage of the oil 114 is provided between the cover 116 and the weight groove 110. The cover 116 and the 15 sealing member 118 are schematically shown in Fig. 4. The cover 116 can be composed of transparent acrylic resin in order to identify the weight member 112 in the weight groove 110.

Figs. 6 and 7 are schematic side views for illustrating positions of a weight ball in the balancing apparatus combined with the wheel grinder to rotate together according 20 to the first embodiment of the present invention.

When the grinding stone 120 and the balancing apparatus 100 rotate together, two weight members 112 having the ball shapes are arranged in the weight groove 110 by a predetermined angle according to the rotation of the balancing apparatus 100.

When the grinding stone 120 and the balancing apparatus 112 rotate at low speed, the 5 arrangement of the weight members 112 is shown in Fig. 6. While the grinding stone 120 and the balancing apparatus 112 rotate at high speed, the arrangement of the weight members 112 is shown in Fig. 7.

Referring to Figs. 6 and 7, Cr means the center of rotation of the grinding stone 120 and the balancing apparatus 112, that is the center of the spindle 1100. G represents 10 the center of mass of the grinding stone 120 and the balancing apparatus 112. Thus, the grinding stone 120 eccentrically rotates and the eccentric direction of the grinding stone 120 turns toward the center of mass G from the center of rotation Cr. At that time, the weight members 112 rotating at low speed are converged in the eccentric direction while the weight members 112 are maintained by a constant angle E concerning the line 15 prolonged from the center of the rotation Cr and the center of mass G as shown in Fig. 6.

Hence, the rotating vibration can be increased since the positions of the weight members 112 are identical to the eccentric direction.

In the other hand, the weight members 112 rotating at high speed are positioned in the direction opposed to the eccentric direction while weight members 112 are 20 maintained by a constant angle F concerning the line prolonged from the center of the

rotation Cor rand the center of mass G as shown in Fig. 7. Hence, the rotating vibration due to the eccentricity can be disappeared.

As it is described above, the balance of the grinding stone 120 can be automatically adjusted according to such operation of the weight members 112 while the grinding stone 120 rotates.

The experimental adjustment effect due to the balancing apparatus 100 of the present invention is measured and shown in the following table.

Table: adjusted values in accordance with the balancing apparatus Balancingapparatus Non-exist Exist Eccentric amount (um) 0.248 0.122 Amount of unbalance (gmm) 19 9. 3

In the above table, the experiment conditions are as follows: two weight members 112 are used, the outer and the inner diameters of the grinding stone 120 is respectively about 180mm and 31.75mm, the grinding stone 120 has a thickness of about 13mm, and the rotation speed of the spindle 1100 is about 3,600rpm.

As shown the above table, the eccentric amount is reduced from about 0.248us to about 0.122um by using the balancing apparatus 100 of the present invention, thereby reducing the eccentric amount by about 50%. Also, the amount of unbalance is decreased from about 19gmm to about 9.3gmm, whereby decreasing the amount of unbalance by about 50%. Thus, the balance of the grinding stone 120 is excellently

adjusted by using the balancing apparatus 100 of the present invention since the eccentric amount and the amount of unbalance are greatly reduced by about 50%.

Embodiment 2 Fig. 8 is a vertically cross-sectional view for illustrating a balancing apparatus according to a second embodiment of the present invention. In Fig. 8, similar numerals are used for the elements identical to those in Fig. 4, and the descriptions concerning such elements will be omitted.

Referring to Fig. 8, the balancing apparatus 200 of the present embodiment has the construction identical to that of the balancing apparatus 100 in Fig. 4 besides a guiding groove 220 having a semicircular shape formed in a weight groove 210 having a rectangular-shaped cross section and a cover 216 having a shape varied according to the shapes of the guiding groove 220 and the weight groove 210.

A semicircular guiding groove 222 is also formed beneath the bottom of the cover 216. Hence, when the cover 216 covers the weight groove 210, the guiding groove 220 of the weight groove 210 combines with the guiding groove 222 of the cover 216 to form a complete circle. As a result, the weight groove 210 of the present embodiment has a circular cross section.

When the weight groove 210 has the circular cross section, it is reduced the noise generated by the weight member 212 rotating in the weight groove 210 and

colliding with the inner face of the weight groove 210. In addition, the vibration of rotation can be decreased since the turbulence in the oil 214 received in the weight groove 210 hardly occurs.

Embodiment 3 Fig. 9 is a vertically cross-sectional view for illustrating a balancing apparatus according to a third embodiment of the present invention. In Fig. 9, similar numerals are used for the elements identical to those in Fig. 4 and the descriptions concerning such elements will be omitted.

Referring to Fig. 9, the balancing apparatus 300 for the grinding stone 120 of the present invention has the construction identical to that of the balancing apparatus 200 in Fig. 8 except a rectangular-shaped weight groove 310 having an inclined bottom and a cover 316 having bottom of which shape is varied according to the bottom of the weight groove 310.

The bottom of weight groove 310 is downwardly inclined toward the center thereof from an outer face of a flange 304 for the grinding stone 120. That is, the inner face of the inclined weight groove 310 is deeper than the outer face of the inclined weight groove 310, so the inclined weight groove 310 has a generally triangular cross section. The bottom of the cover 316 has the shape corresponding to the inclined weight groove 310. Namely, the bottom of the cover 316 is upwardly inclined while the weight

groove 310 is downwardly inclined, so the bottom of the cover 316 properly faces with the weight groove 310. Therefore, the cross section of the weight groove 310 has the generally triangular shape when the cover 316 covers the weight groove 310.

On the other hand, the inclined directions of the bottoms of the weight groove and the cover can be opposed to the above-described case. That is, the bottom of the weight groove 310 is downwardly inclined toward outside from the center thereof while the bottom of the cover 316 is upwardly inclined.

Embodiment 4 Fig. 10 is a vertically cross-sectional view for illustrating a balancing apparatus according to a fourth embodiment of the present invention.

Referring to Fig. 10, a balancing apparatus 400 for the grinding stone 120 has a ring-shaped weight tube 410 having a rectangular cross section instead of the above- mentioned weight grooves 110,210 and 310.

The weight tube 410 is disposed on a flange 404 for the grinding stone 120, which is similar to the weight grooves 110,210 and 310. The weight tube 410 is sealed itself in order to prevent a fluid such as oil 414 filled in the weight tube 410 from leaking. The weight tube 410 is attached to the flange 404 by using a combining member composed of a bracket 422 and a bolt 424.

Meanwhile, a weight member 412 such as a ball is disposed in the weight tube

410 with the oil 414. With such construction, the balancing apparatus 400 of the present embodiment performs the function that elimination of the rotation and the vibration of the grinding stone 120 by the same process identical to the above-described embodiments.

Otherwise, the weight tube 410 has various cross sections such as a circle or a triangle like the second and the third embodiments besides the rectangular shape. Also, the weight tube 410 can be attached to the flange 404 for the grinding stone 120 by welding method instead of the combining member composed of the bracket 422 and the bolt 424.

Embodiment 5 Figs. 11 and 12 are a plane view and a vertically cross-sectional view for respectively showing a balancing apparatus according to a fifth embodiment of the present invention, and Figs. 13 and 14 are a plane view and a vertically cross-sectional view for respectively showing a housing for the balancing apparatus according to the fifth embodiment of the present invention.

As shown in Figs. 11 and 12, a balancing apparatus 500 of the present invention includes a ring-shaped weight housing 510. The weight housing 510 is inserted in a ring-shaped weight groove 520 formed on a flange 504 for the grinding stone 120, and then the weight housing 510 combined with the flange 504 by using a connecting

member such as a bolt or welded to the flange by ultrasonic wave welding method.

The weight housing 510 has the ring shape in which a ring-shaped passage 516 is formed along the circumference thereof as minutely shown in Figs. 13 and 14. In addition, at least one weight member 512 having a ball shape is received in the ring- shaped passage 516. The oil 514 is filled in the ring-shaped passage 516, thereby smoothing the rotary motion of the weight member 512.

In the mean time, to enhance the strength of the weight housing 510, reinforcing members such as lib 518 is preferably formed from bottoms of the inner and outer wall of the ring-shaped passage 516.

The weight housing 510 having such construction is mounted on the flange 504.

As shown in Fig. 11, the weight housing 510 is covered with a ring-shaped cover 522 composed of transparent acrylic resin so as to seal the weight housing 510. The performance of the balancing apparatus 500 of the present embodiment is identical to that of the above-described embodiments, so the performance of the balancing apparatus 500 is omitted.

Embodiment 6 Fig. 15 is a plane view for showing a weight member having a shape of an arch according to a sixth embodiment of the present invention. Un the Fig. 15, a weight member 612 has an arch shape in comparison with the weight members of above-

described embodiments. The arch-shaped weight member 612 has the same curvature as the circumference of the flange for the grinding stone.

Because the arch-shaped weight member 612 has the curvature identical to the circumferential line of the weight groove or the weight tube, the weight member 612 has alternative motion approximately identical to the rotary motion of the ball-shaped weight member according to the rotation speed of the grinding stone.

The arch-typed weight member 612 has the advantage that the vibration is more effectively eliminated comparing to the ball-shaped weight member. That is, the arch- shaped weight member 612 has heavy weight than the ball-shaped weight member when the arch-typed weight member 612 and the ball-shaped weight member are composed of materials having identical unit mass. Thus, to enhance the vibration elimination effect of the balancing apparatus, the number of the arch-typed weight members 612 becomes smaller that that of the ball-shaped weight members while several ball-shaped weight member are demanded. As a result, the arch-types weight members 612 are disposed with the same number as the ball-shaped weight members, thereby enhancing the vibration elimination effect.

Embodiment 7 Fig. 16 is a front view for illustrating a wheel grinder having a pair of balancing apparatuses according to a seventh embodiment of the present invention.

Referring to Fig. 16, the wheel grinder 2000 for the grinding stone of the present embodiment has a first balancing apparatus 2200 and a second balancing apparatus 2210 while the wheel grinder 1000 in Fig. 4 has one balancing apparatus 100.

The first and the second balancing apparatuses 2200 and 2210 respectively correspond 5 to among those balancing apparatuses 100,200 300,400 and 500, so the description concerning the first and the second balancing apparatuses 2200 and 2210 will be omitted.

The first and the second balancing apparatuses 2200 and 2210 are respectively disposed on both sides of the grinding stone 120. Meanwhile, a fixing member 2300 is 10 mounted on the second balancing apparatus 2210 disposed on the right side of the grinding stone 120.

Although one balancing apparatus for the wheel grinder produces good balancing effect of the grinding stone 120, however, the balancing concerning the grinding stone 120 is performed at both sides of the grinding stone when two balancing 15 apparatuses 2200 and 2210 are disposed sides of the grinding stone 120, thereby rapidly accomplishing enhanced balancing for the grinding stone 120.

Meanwhile, as for the above-described embodiments, the weight member having the ball or the arch shape may be worn or fractured by colliding with the inner side of the weight tube or the weight housing during the rotation of the weight member.

20 Because the reduction of the weight of the weight member causes the decreased

vibration elimination of the grinding stone, a shock absorbing film composed of shock- absorbing material is preferably coated on the surface of the weight member so as to solve such problem. For example, the shock absorbing film can be composed of plastic or synthetic resin having predetermined elasticity.

In the above-described embodiments of the present invention, the balancing apparatus of the present invention can be applied to the wheel grinder having a plane construction, a spherical construction or a non-centered construction for the vibration elimination of the grinding stone though the balancing apparatus is applied to the wheel grinder having a cylindrical construction.

While this invention has been described and shown as having multiple designs, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.

Industrial Applicability As it is described above, the balancing apparatus for the grinding stone automatically adjusts the balance of the grinding stone when the grinding stone rotates at high speed. Therefore, the time demanded for adjusting the balance of the grinding

stone becomes shorter.

Also, the balance of the grinding stone can be automatically adjusted during the rotation of the grinding stone, so separate balancing process dose not demanded after the dressing process due to the abrasion of the grinding stone.