JPH0985592A - Drill grinding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the rake angle of a rake surface of a cutting edge on the center side of a drill as it is distant from the rotational center. SOLUTION: A grinding wheel 7 is formed of a rotational disc, a side part grinding surface 71 is formed near the outer peripheral part on one side surface of a grinding wheel main body 73, the side part grinding surface 71 is formed into a curved surface so that the projecting amount in the perpendicular direction may be increased on the grinding wheel main body 73 as it is close to the outer peripheral end, and the side surface grinding surface on the outer peripheral end is a device for grinding a drill center side cutting edge by using the grinding wheel formed in the surface direction of the grinding wheel main body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding device for grinding a rake face of a cutting edge on the center side of a drill.

[0002]

2. Description of the Related Art Recently, a so-called spiral blade drill has been proposed in which the chisel portion at the center of the drill is eliminated and a central cutting edge having a large curvature is formed to improve cutting performance.
The central cutting edge of this spiral blade drill is formed by grinding the central part of the shank top with a grindstone made of a rotating disk, in contrast to a shank having a spiral groove and an outer peripheral cutting edge. In other words, a grinding wheel body consisting of a rotating disk with a side grinding surface formed near the outer periphery of one side surface is rotated about its own axis, and the drill is rotated from its outer circumference to its inner side. By advancing in the surface direction of the grindstone while rotating to, from the center of rotation of the drill tip to the inner end of the outer cutting edge, the rake surface of the center cutting edge is ground by the side grinding surface of the grindstone. I am trying to form.

[0003]

In the above machining method, the rake face of the cutting edge is oriented in the axial direction of the drill (the rake angle is 0) near the center of rotation, but the rake face of the outer peripheral side cutting edge is The rake angle becomes larger from the center toward the outer circumference due to the twist of the twist groove. When drilling with a drill, the outer cutting edge has a longer moving path per rotation of the drill as it approaches the outer circumference, so the rake angle increases accordingly, but there is no problem with cutting on the center side. The blade has a constant rake angle of 0 from the center of rotation to the outer peripheral side thereof, and therefore there is a problem in that the cutting performance of the central cutting edge cannot be sufficiently improved. In order to eliminate such drawbacks, the rake angle of the rake face of the central cutting edge is gradually increased so that the rake angles of both rake faces are the same at the connection part with the rake face of the outer cutting edge. It has been proposed to ensure smooth continuity at the connection between the two rake faces.

However, in order to grind such a rake face, the grindstone body rotating about its own axis must be
By advancing in the plane direction of the grindstone while rotating the drill from its outer periphery to the inner side around its own axis, in the process of forming the rake face of the center side cutting edge, the direction of advance of the drill is gradually changed. It is necessary to increase the rake angle of the rake face. In order to perform such machining, it is necessary to control the drill so that it changes its direction of movement in conjunction with rotation and advance of the drill about its own axis, but this requires a complicated control mechanism. There is a drawback that the processing apparatus becomes large-scale and the apparatus becomes expensive.

Further, even with a drill whose center side cutting edge is formed linearly in a plan view, it is desirable to increase the rake angle as it gets farther from the center of rotation, but such machining has never been performed at all. There wasn't.

The present invention has been made in order to solve such a conventional problem, and the rake face of the center side cutting edge is gradually increased from the rotation center toward the outer peripheral side, and the cutting performance of the center side cutting edge is increased. The present invention provides a drill grinding device that improves the quality.

[0007]

According to a first aspect of the present invention, a central shaft is provided coaxially with a chuck for holding a drill to be ground, a cam attached to the central shaft, and the central shaft is rotatable. A whetstone composed of a moving frame for holding, a rotating means for rotating the central shaft, a holding member held by a fixed frame and abutting on the cam surface of the cam, and a rotating disk arranged at the tip of the drill to be ground. The grinding wheel has a side grinding surface formed in the vicinity of the outer periphery of one side surface of the grinding wheel body, and the side grinding surface has a protrusion amount in the direction orthogonal to the surface of the grinding wheel body as it approaches the outer peripheral end. It is formed in a curved surface so as to increase, and the side grinding surface at the outer peripheral end is formed in the surface direction of the grindstone body.

The guide member for guiding the movable frame may be configured to guide in a direction inclined from the axial direction of the central axis.

With this structure, it is possible to easily perform grinding so that the rake angle gradually increases with the distance from the center of rotation of the rake face of the center side cutting edge curved in a plan view.

According to a second aspect of the present invention, a holding frame that reciprocates in the axial direction of the drill to be ground, a drill chuck rotatably held by the holding frame, and the drill chuck are mounted on the drill shaft. Rotating means for rotating within a certain range of rotation angle field, a grindstone consisting of a rotating disk arranged at the tip of the drill held by the drill chuck, and holding this grindstone and grinding part of this grindstone And a posture changing means for changing the posture of the
A side grinding surface is formed near the outer periphery of one side surface of the grindstone body, and the side grinding surface is formed into a curved surface so that the amount of protrusion in the direction orthogonal to the surface of the grindstone body increases as it approaches the outer peripheral end. The side grinding surface at the outer peripheral edge is formed in the surface direction of the grindstone body.

With this configuration, it is possible to easily perform grinding so that the rake angle gradually increases as the rake face of the straight cutting edge on the center side in plan view is separated from the center of rotation.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In FIGS. 1 and 2, a grindstone 7 is used.
Is the central part of the main body 73 (center point 70) formed in a disk shape
A through hole 74 through which a rotary shaft (not shown) is penetrated is formed, and a plurality of mounting holes 76 for fixing the grindstone to the device are formed in the outer peripheral portion of the center hole 74 in the circumferential direction.
A side grinding surface 71 is formed in the vicinity of the outer peripheral portion of one side surface of the grindstone body 73, and the outer peripheral end portion has a side grinding surface 71.
An outer peripheral grinding surface 72 is formed on the outer peripheral surface of the bent portion by being bent to the opposite side. The outer peripheral grinding surface 72 is
A side surface 77 opposite to the outer peripheral end of the side grinding surface 71.
Is formed on the inclined surface in the direction of increasing diameter. The side grinding surface 71 is the grinding wheel main body 7
3 is formed on an arc surface having a point 75 on the back side as the center of curvature,
Moreover, the side grinding surface 71 becomes closer to the outer peripheral end, and the grinding wheel main body 7
3 is formed into a curved surface such that the amount of protrusion in the orthogonal direction is increased, and the side grinding surface 71 at the outer peripheral end is formed in the surface direction of the grindstone body 73. That is, the side grinding surface 71 has a surface in the surface direction of the grindstone body 73 at the outer peripheral end thereof, and projects the largest in the direction orthogonal to the surface of the grindstone body 73, and the projecting amount becomes gradually smaller toward the center side. Thus, the curved surface is formed with the point 75 as the center of curvature.

The inclination angle θ of the outer peripheral grinding surface 72 is set to 20 ° in the illustrated example, and the diameter F1 of the center hole 74 is 38.
mm, the outer diameter F2 of the grindstone 7 is 154 mm, and the thickness H is 16 m.
m, the radius of curvature R of the side grinding surface 71 is 40 mm, the width B1 of the side grinding surface 71 is 8 mm, and the width of the outer peripheral grinding surface 72 (width in the surface direction of the grindstone body) B2 is set to 5 mm. The above dimensions may be appropriately set according to the size of the drill to be ground.

3 to 5 show the shape of a drill that grinds with the grindstone 7. The drill 1 has a pair of spiral grooves 12 formed on its shank, and the tip of the drill 1 has a point relative to the center of rotation O. A pair of cutting blades 2 are formed symmetrically, and each cutting blade 2 is a substantially straight outer peripheral cutting blade 2b and a central cutting blade that curves from the rotation center O with a large curvature and extends to the inner peripheral end of the outer peripheral cutting blade 2b. It consists of a blade 2a. Then, at the top of the drill 1, there is a flank face 2 behind the center side cutting edges 2a, 2b in the rotational direction.
1 and the back metal 11 are formed. Further, a rake face 20 (having a rake angle of 0) oriented in the axial direction of the drill 1 is formed on the center side cutting edge 2a.
0 is between the back metal 11 and the central chip guide surface 3
Are formed. A rake face 22 is formed on the outer peripheral side cutting edge 2b by the groove bottom surface of the tip of the spiral groove 12. A boundary line 35 between the rake face 22 and the rake face 20 of the center-side cutting edge 2a is formed so as to extend in the axial direction of the drill 1, and is formed between the bottom face 12a of the spiral groove 12 and the center chip guide face 3. Has a boundary line 31 formed therein.

FIGS. 7 and 8 show a grinding device using the above-mentioned grindstone 7, and this device has a moving frame 4, a guide member 44 and a fixed frame 45. The movable frame 4 rotatably holds the center shaft 30, and a sleeve 80 having a cam 8 formed thereon is fitted onto the center shaft 30 so that the center shaft 30 and the sleeve 80 can rotate relative to each other. Have been combined. The front end of the central shaft 30 is provided with a bearing 41, and the rear end thereof is provided with the sleeve 8
0 are respectively supported by the bearings 42. A flange 92 is attached to the rear end of the sleeve 80. A chuck 39 is attached to the front end portion of the central shaft 30 coaxially with the central shaft 30, and a drill 1 for grinding is mounted on the chuck 3.
Held by 9.

An operation flange 9 having an operation handle 90 serving as a rotating means is fixedly attached to the rear end of the central shaft 30, and a projection 91 formed on the operation flange 9 is a recess formed on the flange 92. The central shaft 30 fitted in 93 and fixed thereto by the rotation of the operating flange 9.
While rotating, the rotational force is transmitted to the sleeve 80 via the flange 92. A pair of recesses 93 are formed at point-symmetrical positions, and the projections 91 are alternately inserted into the recesses 93 so that the pair of cutting blades 2a can be ground alternately as will be described later. There is.

A guide member 44 is fixedly arranged on a side portion of the movable frame 4, and a protrusion 40 of the movable frame 4 is movably fitted in a guide groove 43 of the guide member 44 to move the movable frame 4 to the central shaft 30.
It is configured to guide in a direction inclined from the axial direction of the.

A bearing portion 46 is provided on the fixed frame 45, and a shaft 47 penetrating the adjusting member 48 has bearing portions 46 at both ends thereof.
Is held by the adjusting member 48 and is movable along the shaft 47 as shown by the arrow. The adjusting pin 48 can be fixed at an arbitrary position by the stop pin 49. A pin 83 is provided on the adjusting member 48.
A pressing roller (pressing member) 82 is attached by this, and the pressing roller 82 is in contact with the cam surface 87 of the cam 8. The shape of the cam surface 87 of the cam 8 changes in the axial direction, and by moving on the cam surface 87 from the set position of the pressing roller 82 (the position in contact with the cam surface 87),
As will be described later, the center shaft 30 rotates and moves along the guide groove 43, whereby the movement trajectory of the cutting edge 2a of the drill 1 held by the chuck 39 changes. Further, the shape of the cam 8 is regulated by a pressing roller 82 which is crimped onto the cam surface 87 as described later, and is formed so that the grindstone 7 abuts on the rake surface 20 of the cutting edge 2a when the drill 1 moves. Has been done.

Next, the operation of this device will be described. The drill 1 to be ground is held by the chuck 39, and the adjusting member 48 is fixed at a predetermined position by a locking pin 49 so as to draw a predetermined movement locus according to the shape of the cutting edge 2a.
In this state, the movable frame 4 is urged along the guide groove 43 in the direction away from the grindstone 7 by means of a spring or the like, so that the pressing roller 82 is pressure-bonded to the cam surface 87 at a predetermined position. And the projection 9 of the operation flange 9
When the handle 90 is rotated in a state in which 1 is fitted in the recessed portion 93, the cam 8 rotates together with the central shaft 30, and the cam surface 8
The pressing roller 82 that is pressure-bonded to the cam 7 causes the cam 8 to move along the guide groove 43 as the outer diameter of the cam 8 increases.
It will be pushed in the direction of approaching. This makes the moving frame 4
Moves along the guide groove 43, and the pressing roller 82 spirally moves on the cam surface 87, so that the drill 1 advances in an oblique direction while rotating toward the grindstone 7.
The grindstone 7 rotates at a constant position and comes into contact with the rake face 20 of the curved cutting edge 2a near the center of the drill 1 while gradually increasing the contact surface from the center toward the outer periphery. , By this, spiral rake face 2
0 is ground.

The grinding process of the rake face 20 will be described with reference to FIGS.
It will be explained by. First, FIG. 3 and FIG. 4 as a drill.
And has a shape in which the rake face 20 of the central cutting edge 2a and the central chip guide surface 3 are not formed, and is brought into contact with the rotating center O of the tip of the rotating grindstone 7. Then, the drill 1 is rotated around its own axis from the outer circumference to the inner circumference of the grindstone 7. At this time, the orientation of the drill 1 is such that the tip inclined surface 72 of the side shape of the drill 1 and the outer peripheral surface of the grindstone 7 are substantially in the same direction, as shown by the phantom line in FIG. As a result, in the vicinity of the rotation center O of the drill 1, as shown in phantom lines in FIG. 6A and FIG. 3, the outer peripheral grinding surface 72 of the grindstone 7 grinds the central chip guide surface 3 and the side grinding surface. The rake face 20 of the center side cutting edge 2 is ground by 71. Since the rake face 20 formed at this time is only near the outer peripheral end of the outer peripheral ground surface 71, the rake angle becomes zero.

From this state, the drill 1 advances and rotates, and the abutting portion (grinding portion) of the side grinding surface 71 extends from the rotation center O in FIG. 5 to the point 61 → 62 → 63 → on the center side cutting edge 2a. 6
4 → 65, the grindstone 7 increases the depth of the rake face 20 along the curved shape of the center side cutting edge 2a in FIG. 3 and increases the rake angle while increasing the rake angle.
Grind 0. At the same time as this grinding, the outer peripheral grinding surface 72
As a result, the central chip guide surface 3 is ground. When reaching the end portion of the center side cutting edge 2a, as shown in phantom lines in FIGS. 3 and 4 and FIG. 6 (b),
The rake face 20 is ground by most of the outer peripheral ground surface 71, and the rake face 20 having the same rake angle as the rake face 22 at the inner peripheral end of the outer peripheral cutting edge 2b is ground. Therefore, as shown in FIGS. 4 and 5, the center side cutting edge 2a
The rake face 20 and the rake face 22 of the outer peripheral side cutting edge 2b are smoothly continuous, and the boundary line 35 between them is oriented in the axial direction of the drill 1.

The side grinding surface 71 may be formed as a curved surface similar to the side grinding surface 71 on the surface opposite to the grindstone 7, that is, on the tip side surface 77 of the bent portion. The central chip guide surface 3 may be ground after the rake surface 20 of the side cutting edge 2a is ground.

FIGS. 6 (c) and 6 (d) show the cross-sectional shape of the outer peripheral side cutting edge 2b at positions further on the outer peripheral side (positions C-C and D-D in FIG. 4). This shows that the rake angle of the rake face 22 is increased (the degree of increase of the rake angle is slightly exaggerated for clarity).

In the conventional grindstone, as shown in phantom lines in FIG. 2, the side grinding surface 79 is formed in the surface direction of the grindstone main body 73. When grinding is performed in the same manner as above using the grindstone, the grindstone has a center of rotation. Even if it moves from O to the outer peripheral side along the center side cutting edge 2a, the rake angle of the rake surface 20 is always constant and the rake surface 40 oriented in the axial direction of the drill is formed.
At the inner peripheral edge of b, the rake angle of the rake face 22 of the outer peripheral side cutting edge 2b is significantly different, and therefore, as shown in FIGS. 4 and 5, the boundary line 35 between both rake faces is inclined toward the center of the drill 1. It becomes the boundary line 36. Along with this, the boundary line between the central chip guide surface 3 and the bottom surface 12a of the spiral groove 12 is also the line 31.
To the boundary line 37.

By changing the rake face of the cutting edge in this way, the rake angle was 0 on the inner peripheral side from the point 65, but when the point 65 was reached, as shown in FIG. It changes to a rake face with a large rake angle, so the cutting action by the cutting edge 2 of the drill 1 becomes discontinuous, the machinability deteriorates with difficult-to-cut materials, and welding occurs depending on the work material. This causes the inconvenience and causes a trouble in discharging the chips.

If the side grinding surface 79 shown in FIG. 2 is set so as to match the rake angle of the rake surface 22 at the inner peripheral end of the outer peripheral cutting edge 2b from the beginning, the rake surface as described above will be obtained. Can be prevented, but in that case, the rake face of the center side cutting edge 2a near the center of rotation O also has a large rake angle. There is a problem that the strength of the blade 2a becomes weak.

After grinding the rake face 20 at the center, the handle 90 is rotated in the opposite direction to return the moving frame 4 to its original position by the force of the spring. The movable frame 4 is stopped accurately at its original position by a stopper (not shown). Next, the operation flange 9 is slightly retracted in the axial direction to remove the projection 91 from the recess 93, and rotated by 180 ° and fitted into the other recess 93, the cam 8 is left as it is, and the central shaft 30 and the drill coaxial therewith. 1 rotates 180 °. When the same operation as above is performed in this state, the rake face 2 of the other cutting edge 2a of the drill 1 is
Zero grinding is performed.

Since the curvature of the cutting edge 2a differs depending on the thickness of the drill, the stop position of the adjusting member 48 is changed according to the curvature, and the spiral locus of the pressing roller 82 moving on the cam surface 87 is changed. To adjust.

As described above, in this apparatus, the rake face of the curved cutting edge having a complicated shape can be ground by a simple operation of simply rotating the operation handle 90. Further, by changing the shape of the cam in the axial direction and adjusting the position of the pressing member with respect to the cam, it is possible to accurately grind curved cutting edges of various shapes with the same device.

In FIGS. 7 and 8, the drill 1 is constructed to be moved diagonally along the guide groove 43 by the guide member 44, so that the drill 1 can be diagonally advanced simultaneously with rotation. However, instead of providing the guide member 44 as described above, the drill 1 may be guided in a direction orthogonal to the central axis instead of advancing diagonally.

9 to 11 show an embodiment of another device for grinding the drill 1, which is a holding frame (moving frame) that reciprocates along a guide groove 50 formed in the upper surface of the device body 5. ) 55 and a rotation means for rotating the pair of drill chucks 39 attached to the holding frame 55 within the range of a constant rotation angle around the axis of the drill 1, and the tip of the drill 1 held by the drill chuck 39. Stone 7 placed on the floor
And Further, a stopper 50a is provided near the guide groove 50, and the holding frame 55 is provided at a position where the tip of the drill 1 for advancing and grinding the holding frame 55 contacts the grindstone 7.
The tip surface 56a of the base portion 56 is brought into contact with the stopper 50a so that a predetermined amount of grinding is performed.

The base portion 56 of the holding frame 55 is the guide groove 5.
It is fitted in 0 and can reciprocate along the guide groove 50, and the cylindrical portion 97 is rotatably held by the holding portion 57 above this base portion, and the drill chuck 39 is rotatably held at the rear portion of this cylindrical portion 97. The driven gears 95 are integrally mounted on the front portion. A drill chuck 39 is mounted on the front side of the driven gear 95 via a flange 96. A connecting member 58 is provided on the upper portion of the holding portion 57.
The tubular body 86 is attached via the
5 is rotatably penetrated, a drive side gear 85 is attached to the front part of the shaft 15, and the drive side gear 85 meshes with the driven side gear 95.

A flange 88 is formed on the rear portion of the cylindrical body 86, a sleeve 16 is fixed to the rear portion of the shaft 15, and an operation handle 18 protruding rearward is attached to an arm 19 of the sleeve 16. . This operation handle 1
The operation shaft 17 of No. 8 has its distal end inserted through the arm 19 and fitted into a recess 89 formed in the flange 88, thereby preventing the sleeve 16 and the shaft 15 from rotating. Further, as shown in FIG. 11, the flange 88 is formed with the arc-shaped guide groove 14 on the rotation locus of the operation shaft 17. The operation shaft 17 is configured to be movable in its axial direction by an appropriate mechanism (not shown).

The operation handle 18, drive side gear 85,
The driven gear 95 and the like form a rotating means. That is, the operation shaft 1 is grasped by grasping the operation handle 18 with a hand.
7 is retracted in its axial direction to remove its tip from the recess 89, and by fitting it into the guide groove 14, it is moved along the guide groove 14 within a certain rotation range, thereby rotating the shaft 15. be able to. When the drive-side gear 85 integrated with the shaft 15 rotates, the driven-side gear 95 also rotates, and the drill chuck 39 integrated with the driven gear 95 also rotates.

The drive side gear 85 and the driven side gear 9 are
The ratio of the number of teeth to 5 is set to 1: 2, whereby the rotation of the operation handle 18 is decelerated to 1/2 so that precise rotation can be performed during grinding of the drill.

As shown in FIG. 9, the grindstone 7 has its rotating shaft 7
0a is held by the tip of the holding arm 52, and the holding arm 52 is held rotatably around a shaft 51 attached to the apparatus body 5. A retaining pin 53 is attached to the base end portion of the holding arm 52, and these retaining arms 54a and 54b.
A posture changing means is constituted by and. That is, by rotating the holding arm 52 around the shaft 51, the locking hole 5 formed in the main body 5 at the position of the solid line or the position of the phantom line in FIG.
The stopper pin 53 is fixed by being inserted into the 4a and 54b, whereby the grindstone 7 is placed in two inclined postures, a solid line state (first inclined state) and an imaginary line state (second inclined state). I am able to hold. Further, the grindstone 7 is rotatably driven around the rotary shaft 70a by a rotating means (not shown).

In the above example, the rotational force from the operating handle 18 is transmitted by the gears 85 and 95, but the operating handle is attached to the tubular portion 97 or the like so that the tubular portion 97 can be rotated directly. May be.

Next, with the above-mentioned apparatus, FIG. 12 and FIG.
A method of grinding the drill 1 shown in 3 will be described. The drill 1a is different from the outer peripheral side cutting edge 2b similar to the above in that an inner center side cutting edge 2c is formed in a straight line in a plan view. First, drill 1a for grinding
Is held by the chuck 39 as shown in the drawing, and the grindstone 7 locks the stop pin 53 in the locking hole 54a.
The state of the solid line in FIG. 7 is maintained, and the grindstone 7 is rotated by the driving means (not shown). Then, the holding frame 55 is advanced along the guide groove 50, and the flank is ground as the first step. In the first step, the grindstone 7 has its rotation axis 70a orthogonal to the axis of the drill 1a, the drill 1a is not rotated while being held by the chuck 39, and the outer peripheral surface of the grindstone 7 is cut by one of the drills 1a. The flank of the blade is applied in the circumferential direction of the drill 1a to perform grinding. Then, the amount of cutting by the grinding is regulated by the front end surface 56a of the holding frame 55 hitting the stopper 50a (see FIG. 10).

When grinding of one flank is completed, the holding frame 55
Is slightly retracted, the operation handle 18 is pulled in the axial direction to remove the tip end of the operation shaft 17 from the recess 89 of the flange 88, and is rotated once around the shaft 15, and the tip end of the operation shaft 17 is engaged with the recess 89 again. Stop it. One rotation of the operating handle 18 rotates the shaft 15 and the drive-side gear 9 that are integral therewith, and the driven gear 95 and the drill 1a that rotates integrally with the driven gear 95 rotate 180 ° accordingly. Therefore, the holding frame 55 is advanced again and the other flank 23 is ground in the same manner as above.

Then, as a second step, the land portion is ground. In the second step, the grindstone 7 removes the stopper pin 53 from the locking hole 54a and rotates the arm 52 around the shaft 51 to lock the arm 52 in the locking hole 54b, so that the second line shown by the phantom line in FIG. The grindstone 7 is rotated while maintaining the inclined posture of 2. The rotation axis 70a of the grindstone 7 is orthogonal to the axis of the drill 1a, and the outer peripheral surface of the grindstone 7 is ground in the circumferential direction of the drill 1a against the land portion of one cutting edge of the drill 1a.

At the time of the grinding, the operation handle 18 is pulled in the axial direction to remove the tip end of the operation shaft 17 from the concave portion of the flange 88 and fit it into one end portion of the guide groove 14. Then, the operating shaft 17 is moved along the guide groove 14 to rotate the shaft 15 within a certain range. With respect to the rotation range in which the guide groove 14 is formed, the drill 1a rotates by half the rotation range, and the grindstone 7 grinds the land 11, the recess 3a and the rake face 20a during that period. That is, in FIGS. 12 and 13, the grindstone 7 contacts the land portion 11 in the state shown by the line 7a in FIG. 12, and the drill 1a rotates counterclockwise from that state, whereby the grindstone 7 shows the state shown by the line 7b. The outer peripheral surface 72 of the grindstone 7 grinds the concave portion 3a, and the side grinding surface 7
The rake face 20a is ground with 1.

When the recess 3a and the rake face 20a are being ground, the land 11 is ground only on the end side (chip discharge groove side) of the broken line 44 in FIG. The shaving amount of the portion 11 is very small.

As described above, when the drill 1a is slightly advanced while rotating the guide handle 14 by the operation of the operating handle 18, the land portion 11 and the concave portion 3a are ground by the outer peripheral surface of the grindstone 7. At the same time, the rake face 20a is ground by the side grinding face 71. The land portion 11 is largely curved at the portion indicated by the broken line 44, and the land portion 11 as a whole is configured to form a substantially conical peripheral surface having the apex center point O of the drill 1a as its apex.

As described above, the advantage of using the above-mentioned grindstone 7 is exhibited even in a drill in which the central cutting edge 2c is formed in a linear shape. That is, since the depth of the rake face 20a gradually increases as the distance from the rotation center O increases, when the grinding is performed by the side grinding surface 71, the rake angle increases as the distance from the rotation center O increases. The center side cutting edge 2a has excellent cutting performance.
Is formed.

Since the drill 1a is rotated within a half rotation range of the rotating operation of the operating handle 18, the rotating operation of the drill 1a can be precisely performed by the operating handle 18. . Further, as shown in FIG. 14, the outer peripheral surface of the rotary grinder is a rotary shaft 70.
It is also possible to use a machine having a surface parallel to a and to perform the grinding by inclining the rotary shaft 70a with respect to the axis of the drill 1a. In this case, the side grinding surface may be appropriately inclined so that the rake surface is ground by the side grinding surface of the grindstone 7 (side grinding surface 71 in FIG. 1).

[0046]

As described above, according to the present invention, the rake of the cutting edge on the center side of the drill is raked by the device using the conventional rotary disk type grindstone whose side grinding surface is formed into a predetermined curved surface. Since the surface is automatically machined so that the rake angle gradually increases as the distance from the center of rotation increases, it is possible to inexpensively manufacture with a simple configuration. Moreover, the curved center side cutting edge can be easily ground by the invention of claim 1, and the straight center side cutting edge can be easily machined by the invention of claim 2.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view of a grindstone showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of an outer peripheral portion of the grindstone of FIG.

FIG. 3 is a plan view of a drill ground by the grindstone.

FIG. 4 is a side view of FIG. 3;

5 is an enlarged explanatory view of a rotation center portion of FIG.

6A is a sectional view taken along the line AA in FIG. 3, and FIG.
4 is a sectional view taken along the line BB of FIG. 4, (c) is a sectional view taken along the line CC of FIG.
(D) is the DD sectional view taken on the line of FIG.

FIG. 7 is an explanatory horizontal sectional view showing an embodiment of the device of the present invention.

FIG. 8 is a sectional view taken along line EE of FIG. 7;

FIG. 9 is a front explanatory view showing another embodiment of the device of the present invention.

10 is an enlarged vertical cross-sectional view of a main part of FIG.

FIG. 11 is a right side view of FIG.

FIG. 12 is a plan view showing another example of a drill.

13 is a vertical cross-sectional view of the tip of the drill shown in FIG.

FIG. 14 is a schematic explanatory view showing still another embodiment of the device of the present invention.

[Explanation of symbols]

 1 Drill 2 Cutting Edges 2a, 2c Center Side Cutting Edge 2b Peripheral Side Cutting Edge 4 Moving Frame 5 Device Main Body 7 Grinding Stone 8 Cam 18,90 Operation Handle 20,20a Center Side Cutting Edge Scooping Surface 22 Outer Side Cutting Edge Rake Surface 39 Drill Chuck 44 Guide Member 52 Grindstone Holding Arm 55 Holding Frame 71 Side Grinding Surface 72 Peripheral Grinding Surface 73 Grindstone Body 75 Curvature Center 82 Pressing Member

Claims (3)

[Claims] 1. A central shaft coaxially provided on a chuck for holding a drill to be ground, a cam attached to the central shaft, a moving frame for rotatably holding the central shaft, and a guide for the moving frame. A guide member, a rotating means for rotating the central shaft, a holding member held by a fixed frame and abutting against the cam surface of the cam, and a grindstone made of a rotating disk arranged at the tip of the drill to be ground. The grinding wheel has a side grinding surface formed in the vicinity of the outer peripheral portion of one side surface of the grinding wheel main body, and the side grinding surface increases in the amount of protrusion in the direction orthogonal to the surface of the grinding wheel main body as it approaches the outer peripheral end. As described above, the drill grinding device is characterized in that it is formed into a curved surface, and the side grinding surface at the outer peripheral end is formed in the surface direction of the grindstone body. 2. The guide member for guiding the moving frame,
The drill grinding device according to claim 1, wherein the drill grinding device is configured to guide in a direction inclined from the axial direction of the central axis. 3. A holding frame that reciprocates in the axial direction with respect to the drill to be ground, a drill chuck rotatably held by the holding frame, and a constant rotation of the drill chuck about the axis of the drill. Rotating means for rotating within the Kakuno range, a grindstone consisting of a rotating disk arranged at the tip of the drill held by the chuck for drilling, and holding this grindstone and changing the attitude of the grinding part of this grindstone With the attitude changing means, the grindstone has a side grinding surface formed in the vicinity of the outer peripheral portion of one side surface of the grindstone main body, and the side grinding surface is in a direction orthogonal to the surface of the grindstone main body as it approaches the outer peripheral end. The drill grinding device is characterized in that it is formed into a curved surface so as to increase the amount of protrusion, and the side grinding surface at the outer peripheral edge is formed in the surface direction of the grindstone body.