TWI248387B - Grinding tool with a vibration damping device - Google Patents

Abstract

A grinding tool (1) includes a spindle (2) with a shank portion (20) detachably fitted to an output shaft (S) of a machine tool and a sub axis (3) with an upper cylindrical body (30) slidably supported in a fitting hole (2a) of a lower cylindrical portion (22) of the spindle (2). The sub axis (3) has a flange portion (31) with a grinding wheel (5) at a lower end of the upper cylindrical body (30). The sub axis (3) also has an axially extending central through hole (3a). The upper cylindrical body (30) of the sub axis (3) has a pair of elongated apertures (30a) oppositely disposed in the radial direction. A pin (6) is inserted through the elongated apertures (30a) and opposite ends of the pin (6) is fixed to the lower cylindrical potion (22) of the spindle (2) to prevent the sub axis (3) from falling out of the spindle (2). The central through hole (3a) of the sub axis (3) has a screwed portion (3b) into which a screw nut (7) is fitted. A compression spring (8) is provided between the pin (6) and the screw nut (7) in the central through hole (3a). An oil seal (10) as a vibration damping member is provided at a lower opening portion of the fitting hole (2a) of the sub axis (3) to damp vibration of the sub axis (3) during operation.

Description

1248387 V. INSTRUCTION DESCRIPTION OF THE INVENTION (1) Technical field of the invention: A grinding tool holder main vehicle 4 and a sub-shaft, the shaft is slidably mounted. The invention relates to an abrasive tool, in particular In an improvement, the abrasive tool architecture includes an output shaft that can be assembled by a main shaft to a machine tool, the sub-shaft being equipped with the main shaft and having a grinding wheel at a lower end thereof. [Prior Art] ^ In the Japanese Patent Laid-Open Publication No. Hei 8-24 3 9 2 9 discloses an abrasive tool for use in a grinding machine, a machining center machine or the like. The grinding tool is composed of a main shaft and a sub-shaft, and the main shaft is a tapered portion or a shank portion mounted on the output shaft of the machine tool, and a cylindrical portion integrally formed with the tapered portion, the sub-shaft is transmitted through the ball bearing The lower end of the farm has a sub-axis of a grinding wheel at its lower end. The sub-shaft 3 is biased at the lower end of the circular yoke through a compression spring disposed in the sub-shaft to squat in the projecting direction in the projecting direction, and the ink is biased by the action of the force of the compression spring. The sub-axis allows the workpiece or the spindle to produce a line grinding of the workpiece in a horizontal plane. Shooting mobile fans

During operation, since the stepped portion I load on the surface of the workpiece is applied to the grinding tool, the offset load is from the grinding wheel ^ = ~ offset axis 'so the sub-axis will be retracted to the main due to the force of the compression spring The offset load delivered to the grinding wheel will be moderated and stalked into the f-stalk. From * However, in the conventional grinding tool, when the spindle is turned, the grinding is fixed. When the diameter of the grinding wheel is larger, the grinding wheel is assembled in which 2 ruts are high and

The car is severely vibrated by the direction of the direction or the lateral direction. As a result, the child wheel will be in the flutter 1248387 V. The invention description (2) is born. Such high chattering reduces the grinding accuracy and degrades the surface roughness and may make the machine's bearings inoperable. The present invention has been made under these circumstances, and its purpose is to provide an abrasive tool capable of preventing the occurrence of high frequency sounds during operation. SUMMARY OF THE INVENTION According to one aspect of the present invention, an abrasive tool having a vibration dampening device is used in a machine tool, the grinding tool including a main shaft and a sub-shaft; the main shaft has a handle detachably mounted to An output shaft of the machine tool, the sub-axis having an upper cylinder slidably supported in a fitting hole of a lower cylindrical portion of the main shaft. The sub-shaft has a flange portion and a grinding wheel, the grinding wheel being located at a lower end of the upper cylinder. The sub-shaft also has an axially extending central through-hole. The upper cylinder of the sub-shaft has a pair of elongated apertures disposed opposite each other in the radial direction, the elongate apertures being elongated in the axial direction and formed to penetrate the thickness of the upper cylinder. A shaft pin is inserted through the two elongated apertures, and the opposite ends of the shaft pin are fixed to the lower cylindrical portion of the main shaft to prevent the sub shaft from coming off the main shaft. The central through hole of the sub-shaft has a threaded portion into which a nut is fitted. A compression spring is provided between the axle pin and the nut in the central through hole. A vibration damping member is provided to moderate the vibration of the sub shaft during operation. According to another aspect of the present invention, an abrasive tool having a vibration damping device is used in a machine tool, the grinding tool comprising a spindle and a sub-shaft; the spindle having a handle detachably mounted to the machine tool An output shaft, the sub-shaft having an upper cylinder slidably freely supported on the main shaft

314542.ptd Page 8 1248387 V. INSTRUCTIONS (3) The lower end of the sub-shaft of the root is the same as the spring force of the grinding wheel. Similarly, the movement can be caused by vibration damping. The vibration damping device in an assembly hole of the cylindrical portion may be an oil seal. The edge of the oil seal. The sub-shaft has the next bolt of the upper cylinder inserted into the '- bottom wall portion of the sub-shaft from the main shaft. The end of the mouth, the torque, a threaded portion, a screw and the grinding # also have an axial axial through hole: - the threaded portion: the sub-shaft is transmitted to the sub-shaft. To the threaded portion, the spring is collapsed. Under 设, during pressing against the workpiece, apply: μ against the vibration of the compression pin 2 to the lower end of the opening. The outer circumference of the cylinder and the nut of the nut are tempered. The shaft retracts to , and the operation is closed. Therefore, the spindle is attached to the sub-wheel, and the extended square opening is fitted in the center of the central shaft. At the center end of the slow grinding wheel, the central through-vibration member of the main shaft of the main shaft is located at the perforation according to the present invention. To prevent the assembly, the upper opening has a through hole L to be used, and the grinding load is moderated during the operation. During the shaft pin of such a member, the compression pin train is effectively sucked by the sub-case at the flange end of the lip portion. In the middle of the sub-axis. Threading the snail from the vibration of the main shaft cap between the main shaft of the main vehicle during the operation of the main vehicle from the upper side of the 'anti-matching L' in this case' oil seal on the upper circle of the sub-shaft The body, in the same way, the rubber or the shaft of the oil seal vibrates. The lip portion is adjacent to the position of the grinding wheel which will increase the support rigidity of the sub-shaft. The resin portion can also effectively absorb the bearing--for the rolling element and a retainer, and the retainer can be rotated

314542.ptd Page 9 1248387 V. INSTRUCTIONS (4) Dynamically support each rolling element. The gap between the outer diameter of the retainer and the inner diameter of the mounting hole of the main shaft may be from 0.05 to 0.3 mm. The vibration-damping member may be composed of a bearing that is greased and inserted between the fitting hole of the main shaft and the upper cylinder of the sub-shaft. In this case, since the grease applied to the bearing has a vibration-absorbing effect, the vibration generated by the sub-shaft can be effectively absorbed. Further, in this case, since the gap between the retainer and the fitting hole is 0.05 to 0.3 mm, the gap is extremely small, and the oscillation of the retainer itself can be suppressed, making the oscillation of the sub shaft difficult. Passed to the spindle through the retainer. The vibration-damping member may be constructed of a shaft pin or bolt that has been sprayed with a ceramic or cemented carbide alloy on its outer surface by thermal spraying. In this case, since the member for preventing the falling (e.g., the pin or the bolt) is formed of a ceramic or cemented carbide alloy, the rigidity of the member for preventing the falling can be increased. Therefore, when the oscillation of the sub-shaft is transmitted to the member for preventing falling through the compression spring, it is possible to suppress the oscillation of the member itself which prevents the falling, and thus it is possible to effectively absorb the oscillation of the sub-shaft. The grinding wheel can have a cup-shaped cross section and open to the bottom surface. The flange portion of the sub-shaft is fitted to the outer peripheral edge portion of the fitting surface, and the outer peripheral portion of the fitting surface has a gently rising wall portion. The fitting surface is provided with a through hole extending through the fitting surface in the axial direction. In this case, when the grinding fluid is moved radially outward due to the centrifugal force generated by the rotation of the grinding wheel during operation, the rising wall portion surrounding the outer peripheral portion of the fitting surface of the grinding wheel will block Grinding fluid outward

314542.ptd Page 10 1248387 V. INSTRUCTIONS (5) Splash. The abrasive fluid on the assembly surface is thus transmitted through the axial through holes to the surface of the workpiece. Thereby, the grinding wheel wear can be avoided because there is no grinding fluid. In addition, when the grinding wheel of a larger diameter is used and the entire surface of the grinding wheel is used for grinding, the above-mentioned π high-pitch flutter of the sub-shaft is apt to occur. In this case, the grinding wheel is in contact with the workpiece. The range becomes larger and the grinding fluid may become insufficient. Therefore, the grinding wheel will be worn. However, according to the present invention, since the grinding fluid can be surely supplied to the workpiece, it is possible to absorb not only the vibration of the sub-shaft but also the vibration. The first embodiment shows an abrasive tool according to a first embodiment of the present invention. As shown in Fig. 1, the abrasive tool 1 includes a The freely rotatable main shaft 2 and a sub-shaft 3 which is axially slidable relative to the main shaft 2. The main shaft 2 has a tapered shank portion 20 at its upper end. The shank portion 20 is detachably mounted on a machine tool (not shown) a rotatable output shaft S, such as a grinding machine or a machining center machine tool. The main shaft 2 further includes a lower cylindrical portion 2 at the lower end of the shank 20. The lower cylindrical portion 2 2 has a downward Opening a fitting hole 2 a. 3 rotor shaft having a cylindrical fitting hole 30 into the spindle 2 on a 2a, the upper cylinder 30 slidably in the axial line freely through a bearing in the floor branched 4

1111 181 II! Hi III 314542.ptd Page 11 1248387 V. INSTRUCTIONS (β) INSTALLATION - Hole 2a. A flange portion is clamped to the lower end of the upper cylinder for connection to a grinding wheel 5. The upper cylindrical body 3 has an axially extending central through hole 3a formed therein. The upper cylinder 3 尬 of the π尬^ axis / 3 has a pair of axially elongated apertures 3 0 a, and the pair, #β 8 is disposed in the radial direction with respect to the upper cylinder 30, and penetrates the cylinder It is formed by the thickness of 30. A shaft pin _ people and each person 铷 ΛΛΛ ΛΛΛ ΛΛΛ ΛΛΛ. The opposite end 6a of the shaft pin 6 is fixed in the pin hole 21) formed in the main shaft and transmitted to the sub-portion 22, and the torque is transmitted from the main shaft 2 through the shaft pin 6 to the gap so that the sub-axis is elongated: 3 0 a Between a car by

-^ ^ ° ? r 7^1 # 3bi\ VVS : T ^ ^ € J hole 7a for the work of a wrench and H-rectangular or hexagonal 杈" nut 7 in the tooth hole 3a and Axial erosion "^ 8. One end of the compression spring 8 is pressed by the main n to insert a compression spring. The yellow end is pressed against the nut 7. The outer circumference of the compression bomb @\钢6, and the other sub-shaft 3. 8 is biased downwardly by the nut 7 to the bearing 4 and is formed by a thin cylindrical retainer member 4 1 , wherein the balls or the plurality of balls after the ball or roll are formed in the support holes of the retainer 4G. The rotating member 41 is fixedly coupled to the bottom surface of the fitting member 51 in a plurality of shaped grinding wheels 5 having a cup-shaped mounting structure y. A disc-shaped grinding stone 50 is fixed to the projection of the sub-shaft 3 by bolts 9. The edge portion 31 of the shame member 51 is disposed on the lower opening portion of the shaft 2 of the main shaft 2 through a solid-oil seal 10,

314542.ptd Page 12 1248387 V. INSTRUCTION OF THE INVENTION (7) A rubber or resin lip portion or an inner peripheral portion of the oil seal 10 contacts the outer peripheral surface of the upper cylinder 30 of the sub-shaft 3. A slit or recess 3 0 b is formed at the lower end of the upper cylinder 30 of the sub-shaft 3 to grind the upper cylinder 30. First, when grinding a workpiece using the grinding tool 1, the nut 7 should be locked before the axial position of the nut can be properly adjusted. By doing so, the change in the distance between the pin 6 and the nut 7 and the amount of elastic deformation of the compression spring 8 can be changed. Thereby, the compressive force transmitted from the grinding wheel 5 to the workpiece can be adjusted. Next, the output shaft S is rotated and the table (not shown) of the machine tool that fixes the workpiece is horizontally moved. Alternatively, the output shaft S can be moved horizontally. Then, the grinding wheel 5 is pressed against the workpiece to perform grinding of the workpiece. During operation, an offset load applied to the grinding wheel 5 will be absorbed by the contraction force of the force of the compression spring 8 against the spindle 2 with respect to the spindle 3. In this case, since the oil seal 10 is positioned at the lower opening portion of the fitting hole 2a of the main shaft 2, the upper cylindrical system of the sub-shaft 3 is supported by the lip portion of the oil seal 10 at a position adjacent to the grinding wheel 5. Therefore, it is possible to increase the support rigidity of the sub-shaft 3 and to suppress the occurrence of vibration of the sub-shaft 3. Further, in this case, even if the sub-shaft 3 vibrates during the operation, the rubber or resin portion of the oil seal forms a vibration damping function. Therefore, the vibration of the sub-shaft 3 can be effectively absorbed. Further, a gap between the outer diameter of the retainer 40 of the bearing 4 and the inner diameter of the mounting hole 2a of the main shaft 2 is preferably 0.5 to 0.3 mm to suppress the upper cylinder 30 and the main shaft 2 The vibration of the guard ring 40 prevents the sub-shaft 3 from transmitting vibration to the main shaft 2 through the retainer 40. Similarly, grease is applied to the retainer 40

314542.ptd Page 13 1248387 V. INSTRUCTIONS (8) It is preferable to use the inner and outer peripheral surfaces to relax the vibration of the sub-shaft 3 by the adhesive resistance of the grease. For the same reason, grease can also be applied to the outer periphery of the compression spring 8. Further, it is preferable to thermally spray a ceramic or cemented carbide alloy on the outer periphery of the shaft pin 6 to increase the rigidity of the shaft pin 6. Thereby, when the vibration of the sub-shaft 3 is transmitted to the shaft pin 6 through the compression spring 8, the shaft pin will be able to suppress the vibration of itself and thus will be able to effectively absorb the vibration of the sub-shaft 3. With such a method, the generation of high-frequency sound due to the vibration of the sub-shaft 3 can be avoided. Second Embodiment Fig. 2 shows an abrasive tool according to a second embodiment of the present invention. In Fig. 2, the same component symbols represent the same or functionally similar components. In this second embodiment, unlike the first embodiment, a labyrinth seal 15 is used between the main shaft 2 and the sub shaft 3 instead of the oil seal, and the bolts 16 are used to replace the shaft pins. As shown in Fig. 2, a labyrinth seal 15 is provided between the lower end surface 2c of the main shaft 2 and the upper end surface 31a of the flange portion 3 1 of the sub-shaft 3. In Fig. 2, for the purpose of illustration, the labyrinth seal 15 will be displayed in a cross-sectional manner. The labyrinth seal 15 is composed of a plurality of lip portions disposed on one of the end faces 2 c, 3 1 a and a plurality of lips disposed oppositely on the other of the end faces 2 c, 31 1 a The rim is formed to create a different gap between these adjacent lips. Similarly, the bolt 16 is inserted through the upper open end of the upper cylinder 30 of the sub-shaft 3 to prevent the sub-shaft 3 from coming off the main shaft 2. A threaded portion of the bolt 16 is fitted to the bottom wall portion of the fitting hole 2a of the spindle 2. Bolt 1 6 head with

314542.ptd Page 14 1248387 V. INSTRUCTIONS (9) There is a hexagonal socket 16 a for a tool such as a wrench (not shown) to be joined. The bolt 16 also has a hexagonal nut-shaped anti-rotation portion 16b between the head portion and the threaded portion. The upper end of the central through hole 3a of the sub-shaft 3 is fixed to a collar 18 in which a hexagonal hole is formed. The anti-rotation portion 16b of the bolt 16 is fitted into the hexagonal hole of the collar 18. In this way, the torque of the main shaft 2 is transmitted to the sub-shaft 3 through the engagement of the anti-rotation portion 16b of the bolt 16 with the collar 18. A buckle 1 7 is provided at the upper end of the central through hole 3 a to prevent the collar 18 from slipping off the sub-shaft 3. The ceramic or cemented carbide alloy can be sprayed onto the outer peripheral surface of the bolt 16 and the upper end of the compression spring 8 contacts the head of the bolt 16. In this case, since the labyrinth seal 15 is disposed on the upper end surface 31 1 a of the flange portion 3 1 of the sub-shaft 3, the labyrinth seal 15 is supported on the position adjacent to the grinding wheel 5. The cylinder 30, thus increasing the support rigidity of the sub-shaft 3, and the rubber or resin portion of the labyrinth seal 15 can effectively absorb the vibration of the sub-shaft 3. Further, in this case, since the corner of the connecting portion between the upper cylinder 30 and the flange portion 31 does not need to be used to grind the slit or recess of the upper cylinder 30, it is possible to increase the entire sub-axis. The rigidity of 3 is capable of suppressing the vibration of the sub-shaft 3. Further, in this case, the rigidity of the bolt 16 can be increased by spraying ceramic or adding a cemented carbide alloy to the bolt 16. Therefore, when the vibration generated by the sub-shaft 3 is transmitted to the bolt 16 through the compression spring 8, the vibration of the bolt itself can be suppressed, thereby effectively absorbing the vibration and mitigating the vibration of the sub-shaft 3.

314542.ptd Page 15 1248387 V. INSTRUCTION DESCRIPTION (ίο) THIRD EMBODIMENT Fig. 3 shows an abrasive tool according to a third embodiment of the present invention. In Figure 3, the same component symbols represent the same or functionally similar components. In this third embodiment, the structure of the grinding wheel is different from the grinding wheel structure of the first or second embodiment. As shown in Fig. 3, in the grinding wheel 5, a gently rising wall portion 5 1 b extending diagonally upward is formed along the outer peripheral edge portion of the fitting surface 5 1 a of the fitting member 51, and the sub-shaft 3 is formed. The flange portion 31 is attached to the other peripheral portion. Further, the fitting member 51 has an axially extending through hole 5 1 c formed therein, which is open toward the fitting surface 5 1 a and the grinding stone 50. The fitting member 5 1 is fixed to the flange portion 31 of the sub-shaft 3 through a fixing screw 9 that is centered on the fitting member 51. In this case, during operation, when the centrifugal force generated by the rotating grinding wheel 5 causes the grinding fluid to move outward, the rising wall portion 5 1 b on the outer peripheral portion of the fitting member 51 of the grinding wheel 5 will be Prevent the abrasive fluid from spilling outward. Next, the polishing fluid (as indicated by the arrow mark in Fig. 3) on the fitting surface 51a flows through the through hole 5 1 c of the fitting member 51 and is introduced into the grinding stone 50. In this manner, the abrasive fluid will be reliably supplied to the workpiece to avoid wear of the grinding wheel 5 due to the lack of abrasive fluid. Further, the '' high pitch chattering' of the sub-shaft 3 is apt to occur when the grinding wheel 5 has a large diameter and is polished using the entire surface such as the large grinding wheel 5. In this case, the area where the grinding wheel 5 comes into contact with the workpiece becomes larger, and the grinding fluid becomes insufficient, and as a result, the abrasion of the grinding wheel 5 is more likely to occur.

314542.ptd Page 16 1248387 V. INSTRUCTION DESCRIPTION (11) However, according to the third embodiment of the present invention, since the grinding fluid can be surely supplied to the workpiece, the occurrence of high-frequency sound generated by the vibration of the sub-shaft 3 will It can be prevented, and the wear of the grinding wheel 5 can also be prevented. In the first and second embodiments described above, a shaft pin or bolt is used to transmit torque from the main shaft to the sub shaft, however, the present invention is not limited to these examples. The retainer 40 of the bearing 4 may have a polygonal cross section such as a hexagonal cross section, and each cross sectional shape of the fitting hole 2 a of the main shaft 2 and the upper cylinder 30 of the sub shaft 3 may correspond to the retainer The shape of the cross-sectional shape of 40. In this case, the torque of the main shaft 2 will be transmitted to the sub-shaft 3 through the bearing 4. Modifications to the teachings of the present invention, as well as other embodiments, may be made without departing from the spirit and scope of the invention. The described embodiments and examples are to be considered as illustrative only and not limiting of the invention. Therefore, the scope of the invention is indicated by the scope of the appended claims, rather than the description. Therefore, it is apparent that those skilled in the art can modify the structure, the sequence, the materials and the like while still having the scope of the present invention.

314542.ptd Page 17 1248387 BRIEF DESCRIPTION OF THE DRAWINGS [Brief Description of the Drawings] In order to make the present invention more fully understood, the following description of the embodiments of the invention and The examples are provided as a reference, and the drawings are not drawn to scale. Fig. 1 is a cross-sectional front view of an abrasive tool according to a first embodiment of the present invention. Fig. 2 is a cross-sectional front view of the abrasive tool according to the second embodiment of the present invention. Figure 3 is a cross-sectional front view of an abrasive tool in accordance with a third embodiment of the present invention. 1 Grinding tool 2 Spindle 2a Mounting hole 2b Pin hole 2c Lower end face 3 Sub-shaft 3 a Central through hole 3b Threaded part 4 Bearing 5 Grinding wheel 6 Shaft pin 6 a Reverse end 7 Nut 7a Hole 8 Compression spring 9 Fixing bolt 10 Oil seal 15 Diameter steam seal 16 Bolt 16a Hexagon insert 16b Anti-rotation part 17 Buckle 18 Collar 20 Handle 22 Lower cylinder 30 Upper cylinder

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Claims (1)

1248387 VI. Patent application scope 1. An abrasive tool with a vibration damping device for a machine tool, the grinding tool comprising: a spindle having a handle and a lower cylindrical portion, the handle being detachably assembled An output shaft of the machine tool, the lower cylindrical portion is disposed at a lower end of the handle and has a mounting hole; and a sub-shaft having an upper cylinder, a flange portion, and a central through hole, the upper cylindrical system Slidably supported in the mounting hole by a bearing interposed therebetween, the flange portion is disposed at a lower end of the upper cylinder and is equipped with a grinding wheel formed in the sub-shaft and facing An axial extension; wherein the upper cylinder of the sub-shaft has a pair of elongated apertures disposed opposite to each other in the radial direction, the elongated apertures being elongated in the axial direction and formed by penetrating the thickness of the upper cylinder, a shaft pin is inserted through the elongated holes, and the opposite ends of the shaft pin are fixed to the lower cylindrical portion; wherein the central through hole of the sub shaft has a threaded portion formed therein, a nut Fitted into the threaded portion, a compression spring is disposed between the shaft pin and the nut in the central through hole, one end of the compression spring is pressed against the outer peripheral surface of the shaft pin, and the other end is pressed against An upper end surface of the nut; wherein a vibration damping member is disposed to mitigate vibration of the sub shaft during operation. 2. An abrasive tool having a vibration dampening device for a machine tool, the grinding tool comprising: 314542.ptd Page 20 1248387 VI. Patent application: A main shaft having a shank and a lower cylindrical portion, the shank being detachably mounted on an output shaft of the machine tool, the lower cylindrical portion being disposed And a sub-shaft having an upper cylinder, a flange portion, and a central through hole, the upper cylinder system being slidably supported by the bearing interposed therebetween In the assembly hole, the flange portion is disposed at a lower end of the upper cylinder and is equipped with a grinding wheel formed in the sub-shaft and extending in the axial direction; wherein a bolt is inserted into the center of the sub-shaft a top end of the through hole, to prevent the sub-axis from falling off the main shaft, a threaded portion of the bolt is mounted on a bottom wall portion of the mounting hole of the main shaft, and the bolt is disposed at a central through hole of the sub-shaft An upper open end for transmitting torque from the main shaft to the sub-shaft; wherein the central through-hole of the sub-shaft has a threaded portion formed therein, and a nut is fitted into the threaded portion in the central portion A compression spring is arranged between the bolt and the nut in the perforation, one end of the compression spring is pressed against the bolt, and the other end is pressed against the upper end surface of the nut; wherein a vibration-damping member is disposed to operate The vibration of the sub-shaft is moderated during the period. 3. The abrasive tool of claim 1 or 2, wherein the vibration-damping member is an oil seal, the oil seal is disposed at a lower opening of the mounting hole of the spindle, and a lip portion of the oil seal contacts The outer circumference of the upper cylinder. 314542.pld Page 21 1248387 6. Patent application scope 4. The abrasive tool of claim 1 or 2, wherein the bearing is composed of a pair of rolling elements and a retaining ring, the retaining ring can be rotated Each of the rolling elements is freely supported, and the gap between the outer diameter of the retainer and the inner diameter of the mounting hole of the main shaft is 0.05 to 0.3 mm, and the vibration-damping member is lubricated and inserted by grease It is formed by a bearing placed between the assembly hole of the main shaft and the upper cylinder of the sub-shaft. 5. The abrasive tool of claim 1 or 2, wherein the vibration-damping member is formed by the shaft pin or bolt, and the shaft pin or bolt has been thermally sprayed with ceramic or cemented carbide alloy Outer perimeter. 6. The abrasive tool of claim 1 or 2, wherein the grinding wheel has a cup-shaped cross section, the cup-shaped cross section is open to the bottom side, and the flange portion of the sub-axis is assembled At a peripheral portion of the outer surface of the fitting surface, the outer peripheral portion of the fitting surface has a gently rising wall portion formed along the periphery thereof, and the fitting surface has a through hole extending through the fitting surface in the axial direction. 314542.ptd Page 22