JPH09234658A - Method and device for fine chamfering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the fine chamfering of a corner part with a simple structure, and to dispense with the cleaning work of after chamfering. SOLUTION: A grinding wheel 82 is held by a grinding wheel holding member 84, etc., and supported by an oscillating supporting member 76 in an oscillating manner. The grinding wheel 82, the grinding wheel holding member 84, the oscillating supporting member 76, etc., are pressed against a tapered surface of a work by an air cylinder, etc., by rotating the work such as a ferrule, and the grinding wheel 82 is integratedly reciprocated in the direction in which the grinding wheel 82 is across a corner part of the work.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for thread chamfering a corner portion of a work using a grindstone.

[0002]

2. Description of the Related Art Generally, when a corner portion is formed on a work by cutting or the like, thread chamfering is performed to remove a so-called edge at the corner portion. As an example of such a work, a ferrule used for connecting optical fibers to each other is shown in FIGS.

In FIG. 1, 10 is an optical fiber to be connected to each other. Each optical fiber 10 is inserted into a cylindrical ferrule 12 made of ceramic or the like, and each ferrule 12 is inserted into a cylindrical plug 14. Has been done.
Then, as shown in FIG. 2, in a state where both optical fibers 10 and both ferrules 12 are butted to each other in the axial direction,
A split sleeve 16 is fitted on the outer sides of both plugs 14, and the split sleeve 16 is housed in a housing 18 to form a connection structure between the optical fibers 10.

FIG. 3 shows the vertical sectional shape of the ferrule 12. The optical fiber 10 can be inserted into the center hole 12a of the ferrule 12, and the outer peripheral surface 12b has a cylindrical shape. Both end surfaces 12c, 12 of the ferrule 12
The periphery of d is chamfered to form a tapered surface 12.
g and 12h are formed respectively.

In this ferrule 12, the tapered surface 12
Thread chamfering is applied to the corners between g and 12h and the outer peripheral surface 12b and the corners between the tapered surfaces 12g and 12h and the end surfaces 12c and 12d (indicated by "R" in FIG. 3). Conventionally, such thread chamfering is performed by buffing or belt polishing.

[0006]

However, when the chamfering process is performed by the buffing or belt polishing, the polishing amount changes depending on whether the buff or belt is new or old, which makes stable processing difficult. is there. Further, since free abrasive grains adhere to the work holding device and the work surface by the above-mentioned polishing, a cleaning step must be provided after the processing, which disadvantageously increases the number of steps.

In view of such circumstances, it is an object of the present invention to provide a yarn chamfering method and device capable of performing a yarn chamfering process on a corner with a simple structure and not requiring a cleaning operation after the process. .

[0008]

Means for Solving the Problems As a means for solving the above problems, the present invention is a method for chamfering a corner portion of a work with a grindstone over the entire circumference, while rotating the work, While holding the grindstone so as to be swingable, the grindstone is pressed against the corner portion and is reciprocated in a direction straddling the corner portion in a direction in which the swing central axis is substantially parallel to the tangential direction of the corner portion.

According to this method, when the grindstone is reciprocally moved while straddling the corner while pressing the grindstone against the work, the reaction force received from the corner acts as a moment, and the grindstone automatically moves. Rock. By the combination of such reciprocating movement of the whetstone and swing,
The corner portion is curvedly chamfered with only a grindstone. Therefore, unlike the polishing process using a buff or a belt, the cleaning work after the process is unnecessary.

In this method, it is possible to chamfer a plurality of corner portions at the same time by moving the grindstone back and forth so as to straddle a plurality of corner portions that are close to each other.

Further, the present invention is, as an apparatus for carrying out the above method, a work holding means for holding and rotating a work, a grindstone holding member for holding a grindstone, and the grindstone holding member in the tangential direction of the corner portion. A swing support means for swingably supporting about an axis in a direction substantially parallel to and a pressing force in a direction toward the workpiece to the swing support means and the grindstone holding member to press the grindstone to the corner portion. The pressing means, and the chamfering driving means for integrally reciprocating the pressing means, the swing support means, and the grindstone holding member in a direction in which the grindstone crosses the corner portion are provided.

Further, the rocking support member may be configured so that when the grindstone holding member swings from a predetermined neutral position, the grindstone holding member is given a force in the direction of returning the grindstone holding member to the neutral position. For example, even if the reciprocating speed is increased, the wobbling of the grindstone can be reliably followed.

The swing support means is provided between the swing support member and the grindstone holding member, which is connected to the pressing means and on which the grindstone holding member is swingably mounted. It is preferable that the whetstone holding member is elastically deformed as the whetstone holding member swings from the neutral position and an elastic member that urges the whetstone holding member by the elastic return force in a direction of returning to the neutral position. Is. in this case,
A swing support shaft may be provided on the swing support member, and the whetstone holding member may be swingably supported on the swing support shaft. Alternatively, the elastic member may be supported by the whetstone holding member and the swing support member. And may also be used as a swinging member that swingably connects.

As the pressing means, a movable part connected to the swing support member and a suitable position near the work are positioned, and the movable part is movable in a direction in which the grindstone comes in contact with and separates from the work. It is preferable that the movable portion is provided with an urging holding portion that supports and urges the movable portion in a direction toward the work.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of the present invention will be described. In this embodiment, description will be given of a case where a corner portion that is a boundary between the tapered surface 12h and the outer peripheral surface 12b and the end surface 12d in the ceramic ferrule 12 shown in FIG. 3 is thread chamfered with a diamond grindstone 82. To do.

As shown in FIG. 4, the yarn chamfering device in this embodiment comprises a work driving device 20 and a grindstone operating device 40.

In this embodiment, a centerless type is used as the work driving device 20. The details are shown in FIG. The work drive device 20 includes a fixed block 22 installed on a base. A main shaft 23 is rotatably supported on the fixed block 22, and a shoe 26 and a main shaft drive motor 28 are fixed. A support roller 24 is fixed to the front end of the main shaft 23, and the support roller 24 and the shoe 26 are close to each other. A backing plate 25 is fixed immediately behind the upper end of the support roller 24.

A rotating block 34 is attached to the fixed block 22 so as to be rotatable around a support shaft 32 parallel to the main shaft 23. A main shaft 35 is rotatably supported by the rotating block 34 in a direction parallel to the main shaft 23, and a pressure roller 36 is fixed to the front end of the main shaft 35.
The rear ends of both main shafts 23, 35 are connected to the output shaft of the main shaft drive motor 28 via a belt 30, and the operation of the main shaft drive motor 28 causes both main shafts 23, 35 to operate.
Further, both rollers 24 and 36 are simultaneously driven to rotate in the same direction.

A shock absorber 39 is fixed to the base end of the rotating block 34 via a bracket 33. On the other hand, the bracket 37 is provided on the fixed block 22 side.
The pressurizing cylinder 38 is fixed via the pressurizing cylinder 38, and the shock absorber 39 is pressed by the operation of the pressurizing cylinder 38 so that the pressurizing roller 36 holds the ferrule 12 as the work together with the supporting roller 24. . The sandwiched ferrule 12 is provided with the shoes 26 from the side and the backing plate 2 from the rear.
5, respectively, and in this state both rollers 24,
As the roller 36 is driven to rotate, both rollers 24, 36
The components are arranged so that the ferrule 12 sandwiched between the rollers is driven to rotate in the direction opposite to the rotation direction of the rollers 24 and 36.

In the present invention, the concrete structure of the work driving device is not limited, and for example, the work may be grasped by a chuck at the tip of the spindle and the work may be rotationally driven integrally with the spindle.

The side of the work drive device 20 is shown in FIG.
The support wall BT shown in (1) is erected, and the main body of the grindstone operating device 40 is attached to the upper part of the support wall BT.

The grindstone operating device 40 includes a substrate 42, which is fixed to the upper side surface of the support wall BT. A pair of guide bars 44 extending in a diagonal direction close to the vertical direction is fixed to the side surface of the substrate 42, and a slide table 46 is attached so as to be slidable along the guide bars 44. An air cylinder 47 is fixed to the upper end portion of the base plate 42, and the tip end of the telescopic rod 48 is connected to the slide table 46. The slide table 46 is slidably driven by the telescopic operation of the air cylinder 47. ing.

The slide table 46 has a direction orthogonal to the sliding direction (oblique direction close to the horizontal direction).
In addition, a drive conversion device 50 as shown in FIGS. 6 and 7 is provided. This drive conversion device 50 includes a cylinder 52
The reciprocating drive shaft 54 is rotatably supported in the cylinder 52 via a bearing 53. The reciprocating drive shaft 54 is connected to an output shaft of a chamfering drive motor (chamfering drive means) 56 via a speed reducer 55.

On the other hand, a telescopic rod 58 is held at the tip of the cylinder 52. The telescopic rod 58 has a central axis X2 parallel to the central axis X1 of the reciprocating drive shaft 54, and both central axes X1 and X2 are eccentric by a predetermined dimension at a position and orientation which is the same as the central axis at the tip of the cylinder 52. It is supported so that it can slide in any direction. Then, the rear end of the telescopic rod 58 (the left end in FIG. 6) and the reciprocating drive shaft 54
Is connected to the front end (right end in the figure) via a ball joint 60. As the reciprocating drive shaft 54 is driven to rotate by the operation of the chamfer drive motor 56, the telescopic rod 58 causes the telescopic rod 58 to move to the piston. I am exercising.

The outer peripheral surface of the reciprocating drive shaft 54 is
A groove 61 extending in a direction parallel to the axial direction is provided, and a pin 62 fitted in the groove 61 is fixed to the side wall of the cylinder 52. The rod 58 is prevented from rotating.

A support arm 64 extends obliquely downward from the tip of the telescopic rod 58. A grip portion 65 is provided at the tip of the support arm 64.
The air cylinder (pressing means) 66 shown in FIGS.
Is gripped. As shown in FIG. 9A, a piston 70 is housed in the cylinder body 68 of the air cylinder 66 so as to be vertically movable, and a head side chamber (a space above the piston 70) is provided at the upper end of the cylinder body 68. The air supply plug 72 which faces is fixed, and the air having a constant pressure is sent from the air supply plug 72, so that the piston 70 is urged downward by the pressure.

The means for urging the piston 70 downward is not limited to this, and for example, as shown in FIG.
The compression coil spring 71 may be inserted in the head side chamber.

A piston rod 74 extends downward from the piston 70, and a swing support member 76 is fixed to the lower end of the piston rod 74 by a pin 75. The lower end portion of the swing support member 76 branches into a front side wall 76f and a rear side wall 76r which are separated from each other in the front and rear direction. Both side walls 7
6f and 76r are in the front-back direction (left-right direction in FIG. 9A);
Both ends of a swing support shaft 78 extending in the tangential direction of the corner portion are fixed, and a rear grindstone holding member 80 is supported to be swingable about the swing support shaft 78.

The upper half portion 80a of the rear side grindstone holding member 80
Has a thickness dimension slightly smaller than the spacing dimension between the both side walls 76f, 76r, and the lower half portion 80b has a smaller thickness dimension and a larger width dimension than the upper half portion 80a. Then, the upper half portion 80a is formed by the side walls 76f, 7f.
The rear grindstone holding member 80 is supported so as to be swingable around the swing support shaft 78 in a state in which the swing support shaft 78 penetrates the upper half portion 80a while being fitted between the 6r.

Lower half portion 80b of the rear side grindstone holding member 80
Holds the grindstone 82 with the front grindstone holding member 84. More specifically, as shown in FIG. 10, the front grinding wheel holding member 84 is provided with a bolt insertion hole 84h that penetrates the front grinding wheel holding member 84 in the front-rear direction, and the lower half portion 80b is provided with the bolt insertion hole 84h.
The screw hole 80h is formed in the same direction as the above, and the bolt 85 is inserted into the bolt insertion hole 84b while the lower half portion 80b and the front grindstone holding member 84 sandwich the grindstone 82 from the front and rear.
And is screwed into the screw hole 80b. As a result, the rear wheel grindstone holding member lower half portion 80b and the front wheel grindstone holding member 84 are fastened, and the grindstone 82 is held by them while the lower end of the grindstone 82 projects below the grindstone holding members 80, 84. Has been done.

A lower end of a linear spring (elastic member) 86 is fixed to the front grinding wheel holding member 84 in a state of penetrating the front grinding wheel holding member 84, and the upper end of the linear spring 86 is swingably supported by a bolt 98. It is fixed to the member 76. Linear spring 8
No. 6 has a straight shape in a non-deformed state, and is attached so that the lower surface of the grindstone 82 becomes the straight shape at the position (neutral position) orthogonal to the piston rod 74. From this neutral position, the grindstone holding member 80 is provided. , 48 and the grindstone 82 rock and elastically deform (see FIG. 11).

A ring 88 is provided at the front end of the cylinder 52.
Is fixed, and the base end (upper end) of the reinforcing arm 89 is fixed to this ring 88. This reinforcing arm 89 is
The ring 88 extends substantially parallel to the support arm 64, and its tip 89a is in contact with the rear side surface (right side surface in FIG. 12) of the swing support member 76.

This yarn chamfering device is equipped with a control device 90 as shown in FIG. This control device 90
It is composed of a microcomputer and the like, and is configured to perform the following control operation. A control signal is output to the spindle drive motor 28 to control its rotary operation.

A control signal is output to the air switching valve of the pneumatic circuit 92 to control the expansion / contraction operation of the air cylinder 47 connected thereto and the rotation operation of the chamfer drive motor 56.

Next, the operation of the entire apparatus including the control operation of the control apparatus 90 will be described with reference to the graph and time chart of FIG. 14 and FIG.

First, in the work drive device 40, the spindle drive motor 28 operates in response to the output signal of the control device 90 with the ferrule 12 set between the rollers 24 and 36. As a result, both rollers 24 and 36 rotate, and the ferrule 12 rotates in a predetermined direction.

On the other hand, when a control signal is output from the control device 90 to the air switching valve of the pneumatic circuit 92, the air cylinder 47 expands, and the slide table 46, the chamfering drive motor 56, the drive conversion device 50, and the air cylinder 66. ,
The rocking support member 76, the grindstone holding member 84, and the grindstone 82 slidably move integrally downward, and the lower surface of the grindstone 82 makes line contact with the tapered surface 12h of the ferrule 12, as shown by the solid line in FIG. At this time, if the ferrule 12 is driven to rotate in the direction of arrow R in FIG. 12, for example,
A reaction force acts on the grindstone 82 and the grindstone holding members 80, 84 from the ferrule 12 in the direction of arrow F in the figure, but the lower end 89a of the reinforcing arm 89 contacts the rear grindstone holding member 80 from the opposite side. Therefore, the rigidity of the grindstone holding members 80, 84 and the air cylinder 66 as a whole against the reaction force is maintained high.

Next, when the chamfering drive motor 56 is operated and the reciprocating drive shaft 54 is rotationally driven, the movement thereof is converted into a piston movement of the telescopic rod 58a in the front-back direction (left-right direction in FIG. 6), and the support arm. The grindstone 82 is reciprocally driven integrally with the 64, the air cylinder 66, the grindstone holding members 80, 84, etc. in a direction substantially parallel to the lower surface thereof.

Here, when more than half of the lower surface of the grindstone 82 is in contact with the tapered surface 12h of the ferrule 12, the lower surface of this grindstone 82 is kept parallel to the tapered surface 12h, and both are in line contact, When more than half of the lower surface of the grindstone 82 protrudes toward the ferrule outer peripheral surface 12b side, the reaction force of the corner portion which is the boundary between the outer peripheral surface 12b and the tapered surface 12h acts on the grindstone 82 as a moment about the swing support shaft 78. The grindstone 82, together with the grindstone holding members 80 and 84, is tilted about the swing support shaft 78 as the linear spring 86 is bent and elastically deformed (see the left two-dot chain line in FIG. 15). On the contrary, when more than half of the lower surface of the grindstone 82 is separated toward the ferrule end surface 12d, the reaction force of the corner portion which is the boundary between the end surface 12d and the tapered surface 12h acts on the grindstone 82 as a moment, and the grindstone 82 Together with the holding members 80 and 84, the swing support shaft 78 is rotated in the opposite direction and tilted (see the right two-dot chain line in FIG. 15).

That is, the grindstone 82 has a tapered surface 12h.
And the outer peripheral surface 12b and the end surface 12d oscillate in a direction in which the surface which is about to move and the lower surface of the grindstone approach in parallel when straddling the corners (for example, the grindstone 82 is the tapered surface 1).
When moving from 2h to the outer peripheral surface 12b, the outer peripheral surface 12
b is rocked in the direction in which the lower surface of the grindstone 82 approaches parallel)
Therefore, by the swinging and reciprocating movement of the grindstone 82, the corner portion is favorably curved and thread-chamfered. Moreover, unlike the conventional thread chamfering process by buffing or belt polishing, there is no risk of loose abrasive grains adhering to the surface of the ferrule 12 or the like, and a cleaning process after processing is unnecessary.

Next, the second embodiment will be described with reference to FIGS.
7 will be described. In these figures, the structure from the main body of the grindstone operating device 40 to the air cylinder 66 is the same as that of the first embodiment, and the description thereof is omitted.

The rocking support member 76 is provided with a screw hole 76a penetrating it vertically. A male screw 74a is formed at the lower end of the piston rod 74 of the air cylinder 66. The male screw 74a is screwed into the upper half of the screw hole 76a, and a nut 93 attached to the male screw 74 causes the piston rod 74 to move. And the swing support member 76 are connected.

A bolt 95 is attached to the lower half of the screw hole 76a.
Is screwed into the swing support member 7 by the bolt 95.
6, the upper ends of a pair of left and right leaf springs 94 are fixed,
The lower ends of the leaf springs 94 are fixed to the upper half portion 80a of the rear grindstone holding member 80 by bolts 96. That is, the rocking support member 76 and the rear grindstone holding member 80 are connected only by the leaf springs 94.
While the grindstone holding members 80 and 84 swing with respect to the swing support member 76 while accommodating the elastic deformation of No. 4, the lower surface of the grindstone 82 and the axial direction of the air cylinder 66 are orthogonal to each other from the neutral position (the illustrated position). When the whetstone holding members 80, 84 swing, a force in the direction of returning the whetstone holding members 80, 84 to the neutral position is applied by the leaf spring 94.

Thus, in the present invention, the swing support member 7
6 and the whetstone holding members 80, 84 are not directly connected, the rocking support member 76 is formed only by the elastic member via the elastic member.
It is also possible to connect the grindstone holding members 80 and 84.

The embodiment of the present invention is not limited to the above, and the following embodiment can be taken as an example.

(1) FIG. 15 shows a case where two corner portions sandwiching the tapered surface 12h are chamfered at the same time, but the present invention is the case where only one corner portion is chamfered or they are close to each other. It is also effective when chamfering three or more corners at the same time. When simultaneously chamfering two corners, as shown in FIG. 15, the lower surface of the grindstone 82 at the neutral position is substantially parallel to the work surface (tapered surface 12h in FIG. 15) sandwiching both corners. By pressing the grindstone 82 against the work surface with the grindstone 82 facing to and reciprocating so as to straddle both corners, both corners can be evenly and simultaneously chamfered.

(2) In the first embodiment, the linear spring 86, which is an elastic member, may be omitted and only the rear grindstone holding member 84 may be swingably supported by the swing support member 76. If the reciprocating speed is sufficiently low, thread chamfering can be performed. However, as described above, if the biasing force of the linear springs 86 and the leaf springs 94 is applied to the grindstone in the direction to always keep the grindstone in the neutral position, the grindstone 82 can be applied to this even when the reciprocating speed of the grindstone 82 is high. The swing of 82 can be reliably followed.

(3) In the present invention, the work may be any one as long as it has a corner portion over the entire circumference, and its kind and material are not limited. For example, the present invention can be effectively applied to thread chamfering of a liquid spray nozzle. Further, the material of the tool and the like may be freely set according to the type and material of the work. For example, when processing a metal workpiece, it is possible to use a normal grindstone other than diamond.

(4) In the present invention, the mechanism for reciprocally driving the grindstone 82 and the like is not particularly limited, and a cam mechanism, a rack and pinion mechanism or the like can be applied.

[0050]

INDUSTRIAL APPLICABILITY As described above, the present invention is a method for chamfering a corner portion of a work with a grindstone over the entire circumference. While rotating the work, the grindstone is held while being swingable. The rocking central axis is to press the grindstone against the corner portion in a direction substantially parallel to the tangential direction of the corner portion and reciprocate in the direction straddling the corner portion, and as an apparatus for carrying out this method,
Work holding means for holding and rotating a work, a whetstone holding member for holding a whetstone, and a swing support for swingably supporting the whetstone holding member around an axis in a direction substantially parallel to the tangential direction of the corner portion. Means, pressing means for applying a pressing force in the direction toward the workpiece to the swing support means and the grindstone holding member to press the grindstone against the corner portion, the pressing means, the swing support means, and the grindstone holding means. Since the grindstone integrally includes a member and a chamfering drive means for reciprocating the grindstone in a direction straddling the corner portion, the corner portion can be simply moved by pressing the grindstone against the work surface to reciprocate. There is an effect that the thread chamfering process can be satisfactorily performed and a cleaning work such as removal of loose abrasive grains after the process can be omitted.

Further, when there are a plurality of corner portions that are close to each other, the plurality of corner portions can be processed at the same time by moving the grindstone back and forth so as to straddle these corner portions, thereby further improving the processing efficiency. The effect which can be raised is acquired.

Further, the swing support member may be configured so that when the grindstone holding member swings from a predetermined neutral position, the grindstone holding member is given a force in the direction of returning the grindstone holding member to the neutral position. For example, even if the reciprocating speed is increased, it is possible to reliably follow the swing of the grindstone.

Specifically, as the swing support means, a swing support member connected to the pressing means and to which the grindstone holding member is swingably mounted, and the swing support member and the grindstone holding member are provided. And an elastic member that is provided between them and that elastically deforms as the whetstone holding member swings from the neutral position and urges the whetstone holding member by the elastic return force in the direction of returning to the neutral position. According to the present invention, it is possible to obtain the effect that the grindstone can perform a favorable swinging motion with a simple structure.

In the yarn chamfering device,
The surface of the grindstone in the neutral position is pressed in such a direction that the surface of the grindstone is almost parallel to the surface of the work sandwiched between the two corners, and the pressing means is pressed so as to straddle the two corners. According to the method of integrally reciprocating the supporting means and the grindstone holding member, it is possible to obtain an effect that the two corner portions can be efficiently and favorably thread chamfered by one processing operation.

[Brief description of drawings]

FIG. 1 is a perspective view showing a connection structure of optical fibers.

FIG. 2 is a cross-sectional view showing the connection structure.

FIG. 3 is a cross-sectional view of a ferrule used in the connection structure.

FIG. 4 is an overall front view of the yarn chamfering device according to the first embodiment of the present invention.

FIG. 5 is a perspective view showing an example of a work driving device which constitutes the yarn chamfering device.

FIG. 6 is a partial sectional front view showing a chamfering driving means in the yarn chamfering device.

FIG. 7 is a plan view of the chamfering driving means.

FIG. 8 is a front view of an air cylinder, a swing support member, and a grindstone holding member provided in the yarn chamfering device.

9A is a cross-sectional view taken along the line AA of FIG. 8, and FIG. 9B is a cross-sectional front view showing a modified example of the pressing means instead of the air cylinder.

FIG. 10 is a sectional view taken along line BB of FIG. 8;

FIG. 11 is a front view showing a state in which the grindstone holding member is inclined with respect to the swing support member.

FIG. 12 is a side view of an air cylinder, a swing support member, a grindstone holding member, and a reinforcing arm.

FIG. 13 is a block diagram showing a control device installed in the yarn chamfering device and a control target thereof.

FIG. 14 is a graph and a time chart showing a control operation of the control device.

FIG. 15 is a front view showing an operation in which the grindstone swings while being reciprocally driven in the yarn chamfering device.

FIG. 16 is a front view showing a main part of a yarn chamfering device according to a second embodiment of the present invention.

FIG. 17 is a sectional view taken along line CC of FIG. 16;

[Explanation of symbols]

 12 Ferrule (Work) 12h Tapered Surface (Work Surface) 20 Work Drive Device 40 Grindstone Operating Device 66 Air Cylinder (Pressing Means) 68 Cylinder Body (Biasing Holding Part) 70 Piston (Movable Part) 71 Compression Coil Spring (Biasing Hold) 74 piston rod (movable part) 76 swing support member 78 swing support shaft 80 rear grindstone holding member 82 grindstone 84 front grindstone holding member 86 linear spring (elastic member) 94 leaf spring (elastic member)

Claims (8)

[Claims] 1. A method for chamfering a corner portion of a work with a grindstone over the entire circumference, wherein the work is rotated while the grindstone is held so as to be swingable, and the central axis of the swing is the corner. A method for thread chamfering, characterized in that a grindstone is pressed against a corner portion in a direction substantially parallel to the tangential direction of the portion and is reciprocated in a direction straddling the corner portion. 2. The thread chamfering method according to claim 1, wherein the grindstone is reciprocally moved so as to straddle a plurality of corner portions which are close to each other. 3. An apparatus for thread-chamfering a corner portion of a work with a grindstone over the entire circumference, the work holding means for holding and rotating the work, a grindstone holding member for holding the grindstone, and the grindstone holding. A swing support means for swingably supporting the member about an axis in a direction substantially parallel to the tangential direction of the corner portion, and a pressing force in a direction toward the work is applied to the swing support means and the grindstone holding member. And a chamfer drive means for integrally reciprocating the pressing means, the rocking support means, and the grindstone holding member in the direction in which the grindstone crosses the corner portion. A yarn chamfering device characterized in that 4. The thread chamfering device according to claim 3, wherein when the grindstone holding member swings from a predetermined neutral position, a force is applied to the grindstone holding member in the direction of returning the grindstone holding member to the neutral position. A yarn chamfering device, characterized in that the swinging support means is configured to provide the same. 5. The yarn chamfering apparatus according to claim 4, wherein the swing support means is a swing support member connected to the pressing means and the grindstone holding member is swingably attached to the swing support means. Provided between the support member and the grindstone holding member, the grindstone holding member is elastically deformed as the grindstone holding member swings from the neutral position and the elastic return force causes the grindstone holding member to return to the neutral position. A yarn chamfering device, comprising: an elastic member for urging. 6. The yarn chamfering apparatus according to claim 5, wherein the swing support member is provided with a swing support shaft, and the whetstone holding member is swingably supported on the swing support shaft. Thread chamfering device. 7. The yarn chamfering apparatus according to claim 5, wherein the elastic member is also used as a connecting member for swingably connecting the grindstone holding member and the swing support member. Processing equipment. 8. The yarn chamfering apparatus according to any one of claims 3 to 7, wherein the pressing means is a movable portion connected to the swing support means, and is positioned at an appropriate position near the workpiece. Thread chamfering, comprising: the movable portion movably supported in a direction in which the grindstone approaches and separates from the work, and a biasing holding portion that applies a biasing force to the movable portion in a direction toward the work. Processing equipment.