JPH07237018A - Drill - Google Patents

Abstract

PURPOSE:To enhance the versatility of the drill from a high hardness material to a soft material, high hardness thin-walled material, and the like, to say nothing of the boring of steel. CONSTITUTION:The tip of a drill body is provided with a cutting edge formed of an outer peripheral side web-up first cutting edge 6 extended linearly in the length of 0.2XD-0.4XD in relation to the outer diameter D of a drill, and a second cutting edge 7 reaching the rotational center C of the drill, describing a protruding curve more protrusive than the first cutting edge 6. The protruding quantity delta of the second cutting edge 7 to the first cutting edge 6 is set to be 0.01XD-0.05XD, and the radius of curvature phi in the vicinity of the top part H of the second cutting edge 7 is set to be 0.15XD-0.5XD. A chip discharge groove 2 is formed of three grooves arranged in order, and the first cutting edge 6 is formed at the tip side ridgeline part of the first groove 10. The width W3 of the third groove 12 is set to be 0.03XD-0.2XD, and the radius of curvature (r) of the second groove 11 is set to be 0.9XR-1.2XR in relation to the radius R of a circle in contact with a drill outer diameter circle ED and a drill web thickness part circle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drill which can be used not only for drilling steel materials, but also for drilling high hardness materials, aluminum materials, and high hardness thin materials.

[0002]

2. Description of the Related Art In a drill used for drilling a metal-worked material, the drill body is inserted into a drilled hole whose periphery is closed to carry out the drilling process. Is considered important. Then, as a drill for improving the shape of the cutting edge and the shape of the chip discharge groove in order to obtain such high chip disposal performance, for example, Japanese Patent Publication No. 5-32164 and Japanese Patent Publication No. 61-30845.
There is no shortage of enumerations such as those listed in the official gazette.

[0003]

However, the drills described in these publications are intended mainly for the drilling of steel materials. For example, the drills such as various alloys having higher hardness than general steel materials are used. When the above conventional drill is used for drilling hard materials, conversely soft materials such as aluminum with low hardness, or thin materials that are hard to secure the strength of processed materials This will cause problems. That is, in the case of drilling a high-hardness material, the chips are relatively finely divided, but depending on the shape of the cutting edge or the chip discharge groove, the cutting edge or the drill body may be damaged or broken due to the load during processing. There is a risk. On the other hand, in the case of drilling a soft material such as aluminum material, the load applied during processing is small and the cutting edge is unlikely to be damaged, but it is necessary to consider the welding of chips. . Further, in the case of drilling a high-hardness thin material, a drill having a cutting edge strength that can withstand high-hardness cutting and a low cutting resistance required for thin-material cutting is required.

The present invention has been made under such a background, and is applicable not only to the drilling of general steel materials but also the drilling of high hardness materials, soft materials or high hardness thin materials. It is intended to provide a highly versatile drill to be obtained.

[0005]

In order to solve the above problems and to achieve the above object, the present invention provides a chip discharge groove on a side surface of a drill body rotated about an axis from a tip end toward a base end side. Is formed, and a bottom edge of this chip discharge groove and a tip edge flank of the drill main body is a drill formed by forming a cutting edge facing the direction of rotation of the drill at the ridge line portion,
0.2 × D with respect to the outer diameter D of the drill when viewed from the tip in the axial direction
The first blade is linearly extending from the outer circumference of the drill toward the inner circumference with a length of ~ 0.4 × D, and the first cutting blade extends from the inner circumference end to the inner circumference side. And a second cutting edge reaching the drill rotation center after drawing a convex curve projecting in the drill rotation direction than the first cutting edge, and the projection amount of the second cutting edge with respect to the first cutting edge. While setting in the range of 0.01 × D to 0.05 × D with respect to the outer diameter D of the drill, the chip discharge groove is provided with bottom surfaces that are concavely curved in a cross section orthogonal to the axis, and the margin side is provided. To the heel side, the first, second, and third grooves are formed in order, and the first groove is formed so that the first cutting edge is formed at the ridge line portion where the bottom surface and the tip flank face intersect. And the width of the third groove is 0.03 × D to 0.2 with respect to the outer diameter D of the drill.
The radius of curvature of the bottom surface of the second groove is set to a range of × D, and the radius of curvature of the circle inscribed in the drill outer diameter circle and circumscribed in the drill core thickness portion is 0.9 × R ~ 1.2 x R
It is characterized in that it is set in the range of.

[0006]

In the drill having such a structure, first, the cutting edge is composed of the linear first cutting edge on the outer peripheral side and the curved second cutting edge on the inner peripheral side. By arranging the blades to the center of the core, the radial rake angle is set to the negative angle side to secure cutting edge strength, while the length is 0.2 × D to 0.4 × D with respect to the drill outer diameter D. By doing so, it is possible to prevent the cutting resistance acting on the entire cutting edge from becoming excessive.
Here, the length of the first cutting edge is 0.2 with respect to the outer diameter D of the drill.
If it is less than × D, the strength of the cutting edge cannot be secured, and there is a possibility that defects may occur particularly in the outer peripheral portion of the cutting edge, and conversely 0.4 ×
When it exceeds D, the cutting resistance acting on the entire cutting edge is increased, and a wide chip is generated by the first cutting edge, which may hinder smooth cutting of chips.

On the other hand, the second cutting edge connected to the inner peripheral edge of the first cutting edge is projected from the first cutting edge side toward the drill rotation center side, and once in the drill rotation direction side of the first cutting edge. It is formed so as to reach the drill rotation center after drawing a curve and swelling.On the inner peripheral side of the peak of this convex curve, the radial rake angle of the second cutting edge is the radial rake of the first cutting edge. It becomes larger on the regular angle side than the angle. For this reason, it is possible to enhance the sharpness on the inner peripheral side of the cutting edge, and in combination with limiting the length of the first cutting edge, it is more certain that the cutting resistance of the entire cutting edge becomes excessive. Can be suppressed.

Further, in the present invention, the chip discharge groove is composed of first, second, and third grooves having bottom surfaces that are concavely curved in a cross section orthogonal to the axis and arranged from the margin side to the heel side. Of these, the first groove provided on the margin side of the chip discharging groove is formed so as to be continuous with the base end side of the first cutting blade, and therefore its width is the same as the length of the first cutting blade. The outer diameter D is set to 0.2 × D to 0.4 × D. Further, the bottom surface is formed to be concave in the cross section orthogonal to the axis line as described above, and by giving a predetermined tip angle to the tip side portion of this bottom surface, the intersection with the tip flank of the drill body is formed. The straight first blade is formed on the ridge portion as described above. Then, the chips generated by the first cutting blade are guided to the first groove and introduced into the second groove, which will be described later, involved in chip cutting. Further, the third groove provided on the heel side opposite to the first groove is for ensuring the strength of the drill body in the heel portion and for promoting the supply of cutting oil into the chip discharge groove. Yes, its width is 0.03 x D to 0.0 with respect to the drill outer diameter D.
It is set in the range of 2 × D. That is, if the width of the third groove is less than 0.03 × D, the wall thickness near the heel of the drill body becomes small and chips easily occur, and the supply of cutting oil into the chip discharge groove becomes easier. It can be difficult. On the contrary, when the width of the third groove exceeds 0.2 × D, the width of the second groove becomes relatively narrow, and there is a possibility that sufficient chip cutting cannot be performed.

On the other hand, the chips generated by the first cutting blade and flowing out into the first groove as described above are curled and divided while being guided by the second groove and abrading the bottom surface thereof. Here, if the curled chips are brought into sliding contact with the inner peripheral surface of the machining hole, the cutting resistance increases and the machining surface accuracy deteriorates, and efficient chip division is hindered. It is desirable to be curled as it is stored inside. Therefore, it is desirable that the chips are curled ideally so that they are inscribed in the outer diameter circle of the drill and smaller than the circle circumscribing the core thickness of the drill, and the radius of curvature of the bottom surface of the second groove is also It is desirable to set according to the radius of the circle. However, in reality, the chip thickness depending on the material of the processed material and the processing conditions, the easiness of curling of the chips depending on the outflow speed, etc. slightly change, and if the chips are forcibly curled to a small curl diameter, The chips are broken in the middle of curling, and conversely, the discharging property is impaired and the chips are clogged. On the other hand, if the curl diameter is too large, the chips will not be sufficiently curled and the cutting will not be promoted, or the chips will slide on the inner peripheral surface of the machined hole as described above, leading to an increase in cutting resistance. Will result.

Therefore, in the present invention, the radius of curvature of the bottom surface of the second groove is 0.9 × R to the radius R of the circle inscribed in the outer diameter circle of the drill and circumscribing the thick core portion of the drill.
By setting the range to 1.2 × R, it is designed to ensure the chip discharge property and to efficiently divide the chips regardless of the material of the processing material and the processing conditions. That is, by setting the radius of curvature of the second groove to be 0.9 × R or more with respect to the radius R of the circle, it is possible to prevent the chips from being broken in the middle due to the forced and rapid curl, and to obtain a good chip discharging property. On the other hand, by keeping the radius of curvature to be 1.2 × R or less, it becomes possible to sufficiently curl the chips without sliding them against the inner circumference of the machined hole.

[0011]

1 to 4 show one embodiment of the present invention. In this embodiment, the drill body 1 is made of cemented carbide and has a substantially columnar shape. A blade portion is provided at the tip of a shank (not shown), and the drill rotates from the tip of the blade portion toward the base end side. Direction (counterclockwise direction in the figure)
The two chip discharge grooves 2 and 2 twisted to the rear side are formed at equal intervals in the circumferential direction, and these chip discharge grooves 2 and 2 are formed.
And a pair of cuts facing the drill rotation direction side symmetrically with respect to the drill rotation center (intersection point of the tip flank 3 and the axis O) C of the tip flank 3 at the ridge line portion intersecting with the tip flank 3 of the drill body 1. The blades 4 and 4 are formed. In addition, cross-thinning is applied to the edge of the tip flank 3 on the rear side in the drill rotation direction, whereby the tip flank 3 is thinned so as to incline toward the base end side toward the rear in the drill rotation direction. Surfaces 5 and 5 are formed.

The cutting blade 4 has a first blade 6 extending linearly from the outer periphery of the drill body 1 toward the inner periphery as shown in FIG. And a second cutting edge 7 reaching a drill rotation center C while drawing a convex curve swelling in the drill rotation direction from the inner peripheral end of the. The length L of the first cutting blade 6 is 0.2 × D with respect to the outer diameter D of the drill.
It is set to be in the range of up to 0.4 × D, and is located on the drill rotation direction side with respect to the straight line A that passes through the drill rotation center C and is parallel to the first cutting edge 6 when viewed from the tip of the axis O direction. It is arranged so-called center up. However, it is preferable that the amount B of the center rise is set to about 0.05 × D to 0.2 × D with respect to the drill diameter D, although it depends on the material of the processed material, processing conditions and the like. Since the cutting blades 4 and 4 are formed symmetrically with respect to the center of rotation C of the drill, the first cutting blades 6 and 6 are formed parallel to each other when viewed from the front end in the direction of the axis O, and the straight line A is It will be placed in the middle.

The second cutting edge 7 extends from the inner peripheral end of the first cutting edge 6 toward the inner peripheral side at the intersection of the inner peripheral edge of the thinning surface 5 and the tip flank 3 and is located at the drill rotation center C. It is formed to reach. Here, the second cutting edge 7 is once drilled with respect to the extension line of the first cutting edge 6 from the inner peripheral end of the first cutting edge 6 toward the drill rotation center C side in the end view in the direction of the axis O. It is formed so as to project along a convex curve in the rotation direction side, and then to extend to the inner peripheral side, cross the extension line, and reach the drill rotation center C. And by forming in this way, the radial rake angle of the second cutting edge 7 is the diameter of the first cutting edge 6 toward the drill rotation center C side on the inner peripheral side from the top H of the convex curve. It is formed so as to gradually become larger on the regular angle side than the direction rake angle. In addition, the protrusion amount δ of the top H of the second cutting edge 7 is 0.01 × D to 0.1 × D from the first cutting edge 6 with respect to the outer diameter D of the drill in the tip view in the direction of the axis O in the present embodiment. The range is 05 × D. The convex curve formed by the second cutting edge 7 when viewed from the front end in the direction of the axis O is a radius of curvature φ of 0.15 × D to 0.5 × D with respect to the drill outer diameter D in the vicinity of the top H.
Is formed. Furthermore, this second cutting edge 7
It is desirable that the convex curve formed by the arrow when viewed from the front end in the direction of the axis O be formed in a spiral shape whose radius of curvature gradually changes as the distance from the inner peripheral end side of the first cutting blade 6 increases. Furthermore, a portion of the inner peripheral side of the second cutting edge 7 reaching the drill rotation center C may be formed in a linear shape to form a third cutting edge.

On the other hand, the chip discharge groove 2 connected to the base end side of the cutting edge 4 has a margin 8 of the drill body 1 as shown in FIG.
The first groove 10, the second groove 11, and the third groove 12 are arranged in this order from the side toward the heel 9 side. These first, second, and third grooves 10, 11, 12 are
The drill body 1 is formed so as to be twisted according to the twist of the chip discharge groove 2 with a substantially constant width from the tip end toward the base end side. Further, the bottom surfaces 10A, 11A, 12A of the respective grooves 10, 11, 12 are all formed in a concave curved surface shape as shown in FIG. Has been done.

Of the grooves 10 to 12, the first groove 10 located on the margin 8 side is formed with the first cutting edge 6 at the ridge line where the bottom surface 10A and the tip flank 3 of the drill body 1 intersect. Therefore, the width W of the first groove 10 is
₁ is in the range of 0.2 × D to 0.4 × D with respect to the outer diameter D of the drill in accordance with the length L of the first cutting blade 6. Further, the bottom surface 10A of the first groove 10 and the margin 8 on the side surface of the drill body 1 are formed so as to intersect each other at an obtuse angle. Further, the bottom surface 10A of the first groove 10 is formed so as to be curved in a cross section orthogonal to the axis O as described above, and a predetermined tip angle is formed in a portion on the tip side of the first groove 10. By attaching it, the linear first blade 6 as described above is formed. On the other hand, the width W _{3 of} the third groove 12 located on the heel 9 side opposite to the first groove 10 is 0.03 × with respect to the drill outer diameter D.
It is set within the range of D to 0.2 × D, and the three grooves 10 to
It is formed to be the narrowest of the twelve. Further, in the present embodiment, the third groove 12 is arranged such that the bottom surface 12A thereof extends substantially in the radial direction with respect to the axis O in the cross section orthogonal to the axis O, as shown in FIG.

The second groove 11 arranged between these first and third grooves 10 and 12 is the groove which is recessed most radially inward of the drill body 1 among the three grooves 10 to 12, Therefore, the core thickness T of the drill of this embodiment is determined by the depth of the second groove 11. The size of the core thickness T depends on the material of the processed material, processing conditions, etc., but the drill diameter D
On the other hand, it is desirable to set it to about 0.1 × D to 0.35 × D. In the present embodiment, the bottom surface 11A of the second groove 11 is formed so as to have a substantially arc shape in a cross section orthogonal to the axis O, and the radius r of this arc.
Is 0.9 × R to 1.2 × R with respect to the radius R of the circle E _R inscribed in the outer diameter circle E _D of the drill and circumscribing the circle E _T formed by the drill core thickness portion 13 in the cross section. It is set to fall within the range. However, the drill outer diameter circle E _D here is a circle whose diameter is the drill outer diameter D with the axis O as the center in a cross section orthogonal to the axis O, and the drill core thickness portion 13
A circle E _T formed by is a circle having the core thickness T as a diameter with the axis O as the center in the same cross section. In addition, this second groove 1
The bottom surface 11A of 1 may be a concave curved surface having a radius of curvature within the above range even if its cross section is not a strict circular arc.

Further, in this embodiment, the second groove 11 is formed.
Is the rotation center C of the drill as viewed from the front end in the direction of the axis O.
An imaginary straight line F that passes through and extends in a direction perpendicular to the first blades 6 and 6
And a distance S between the straight line G that is parallel to the virtual straight line F and is in contact with the concave curve formed by the bottom surface 11A of the second groove 11 is
The outer diameter D of the drill is 0.1 × D or less. That is, as shown in FIG. 1, in a front end view in the direction of the axis O, with respect to an arc-shaped concave curve formed by the ridge line portion 14 intersecting the bottom surface 11A of the second groove 11 and the thinning surface 5,
Similarly, when a virtual straight line F extending in a direction perpendicular to the first blades 6 and 6 through the drill rotation center C when viewed in the direction of the axis O, that is, a virtual straight line F orthogonal to the straight line A at the drill rotation center C is assumed. , The second groove 1 seen from this virtual straight line F
The distance S between the groove bottom of No. 1 (contact point between the concave curve formed by the intersecting ridge line portion 14 and the straight line G) and the virtual straight line F is 0.1 × D.
The settings are as follows. However, in FIG. 1, although the intersecting ridge line portion 14 does not intersect the virtual straight line F and the straight line G and the groove bottom Q are located rearward of the virtual straight line F in the drill rotation direction, on the contrary, the intersecting ridge line portion 14 is virtual. Straight line F
In some cases, the straight line G and the groove bottom Q may be located on the side of the virtual straight line F on the drill rotation direction side by intersecting with. Even in such a case, however, it is desirable that the distance S between the virtual straight line F and the straight line G be 0.1 × D or less.

On the other hand, FIG. 2 is a side view of the drill taken in a direction orthogonal to the axis O and the first blades 6 and 6, that is, the arrow X direction in FIG. 1, as shown in FIG. In this side view, a virtual circle E _C with a diameter equal to the drill outer diameter D is drawn around the center of rotation C of the drill at the tip of the drill body 1, and this virtual circle E _C and the second chip discharge groove 2 in the side view are drawn. Let P be the intersection of the groove 11 with the ridgeline on the tip side, that is, the intersection of the imaginary circle E _C and the ridge 14 in the present embodiment, this intersection P is the ridgeline in the direction of the axis O in FIG. When projected on 14, the position of the projected intersection point P is the drill rotation center C when viewed from the front end in the direction of the axis O.
From the outer diameter D of the drill to the outer peripheral side of the range of D / 3. That is, in FIG. 1 when viewed from the front end in the direction of the axis O, the diameter of the drill rotation center C (axis O) is 2/3 ×
Assuming a circle E _O of D, the ridge line portion 1 in FIG.
The intersection point P projected on 4 is located on the outer peripheral side of the circle E _O.

However, depending on the inclination of the thinning surface 5, the intersection P with the virtual circle E _C in FIG.
Ridge 1 where the bottom surface 11A of 1 and the thinning surface 5 intersect
4 may be located on the ridge line portion 15 where the bottom surface 12A of the third groove 12 and the thinning surface 5 intersect, but even in such a case, FIG.
, The intersection point P is on the outer peripheral side from the range of D / 3 with respect to the drill outer diameter D from the drill rotation center C, that is, the circle E.
_It is desirable to be placed outside _O.

In the drill having such a construction, the cutting edge 4 is composed of a linear first cutting edge 6 located on the outer peripheral side and a convex curved second cutting edge 7 located on the inner peripheral side. By arranging the first cutting edge 6 to be centered upward and setting the radial rake angle to the negative angle side, it is possible to secure high strength for the entire cutting edge 4. On the other hand, by setting the length L of the first cutting edge 6 to 0.2 × D to 0.4 × D with respect to the drill outer diameter D, the radial rake angle of the first cutting edge 6 is thus increased. By setting the negative angle, it is possible to prevent the sharpness of the entire cutting edge 4 from being dulled, and it is possible to prevent the cutting resistance acting on the entire cutting edge 4 from becoming excessive.

Further, the second cutting edge 7 formed on the inner peripheral side of the first cutting edge 6 projects so as to draw a convex curve with a projection amount δ toward the drill rotation direction side with respect to the first cutting edge 6. After that, it is formed so as to reach the drill rotation center C. Therefore, on the inner peripheral side of the top H of this convex curve, the radial rake angle of the second cutting edge 7 is the radial rake of the first cutting edge 6. It will be set to be larger on the regular angle side than the angle. Therefore, since it becomes possible to give the second cutting edge 7 a sharp cutting edge on the inner peripheral side of the top H, the length L of the first cutting edge 6 is set within a predetermined range as described above in the drill having the above configuration. Combined with the limitation to the above, it is possible to more effectively suppress and reduce the cutting resistance that acts on the entire cutting edge 4. Therefore, according to the drill having the above-mentioned structure, it is possible to prevent the cutting edge 4 from being damaged due to the high cutting edge strength for a processed material having high hardness such as various alloys. With respect to such a soft processed material, it is possible to maintain sharpness and prevent occurrence of welding and the like. Further, it becomes possible to deal with the drilling of a high hardness thin material which requires sufficient cutting edge strength and low cutting resistance without any trouble.

In the above drill, the length L of the first cutting edge 6 of the cutting edge 4 is 0.2 × D to 0.4 × with respect to the drill outer diameter D.
Although the range is D, the length L of the first blade 6 is 0.2 ×
If it is less than D, the strength of the cutting edge cannot be ensured, and there is a possibility that the outer edge of the cutting edge 4 may be damaged. On the contrary, when the length L of the first cutting blade 6 exceeds 0.4 × D, the portion where the radial rake angle is on the negative angle side becomes too large and the cutting resistance acting on the entire cutting blade 4 increases. In addition, the long first blade 6 produces wide chips, which may impair the chip breaking property. Furthermore, in the above-mentioned drill, the amount B of the centering of the first cutting blade 6 is set to 0.05 × D.
Although it is set to 0.02 × D, if the amount of core rising B is too small, the strength of the cutting edge becomes insufficient. On the contrary, if the amount B of center rising is too large, the rake angle of the first blade 6 in the radial direction becomes small. The cutting angle may become too large on the negative angle side, resulting in excessive cutting resistance. Therefore, regarding the amount B of the centering of the first blade 6,
It is desirable to set within the above range.

Further, in the above-mentioned drill, the protruding amount δ from the first cutting edge 6 of the convex curve drawn by the second cutting edge 7 of the cutting edge 4 is 0.01 × D-0. Although it is set to 05 × D, if the protrusion amount δ is smaller than 0.01 × D, the above-described effect of suppressing the cutting resistance by the second cutting edge 7 may not be sufficiently achieved. is there.
On the other hand, when the protrusion amount δ exceeds 0.05 × D, the formation of the second groove 11 of the chip discharging groove 2 is hindered and the first end of the chip discharging groove 2 is formed. Between the groove 10 and the second groove 11, a standing wall is formed so as to be continuous from the inner peripheral end of the first cutting blade 6 to the portion of the second cutting edge 7 to the top H, whereby the first wall is formed. The introduction of chips from the groove 10 into the second groove 11 may be hindered. Furthermore, if the radius of curvature φ in the vicinity of the apex H of the convex curve formed by the second cutting edge 7 is too small, the apex H becomes a sharp shape and chips or the like are likely to occur, and conversely the radius of curvature φ is too large. And the second cutting edge 7 becomes closer to a flat shape, and the cutting edge 4
The sharpness as a whole may not be expected. Therefore, the radius of curvature φ of the second cutting edge 7 is preferably set in the range of 0.15 × D to 0.5 × D as in the present embodiment.

On the other hand, in the drill having the above structure, the chip discharge groove 2 is composed of the first, second and third grooves 10, 11 and 12, of which the first groove 10 is the bottom surface 10A thereof. The first cutting edge 6 is formed on the ridge line intersecting with the tip flank surface 3, and as shown in FIG. 4, the chips K produced by the cutting edge 4 in particular are the first Flowing out into the groove 10 and rubbing the bottom surface 10A of the first groove 10,
The curl is ready. Further, the bottom surface 10A
While being guided to the inner peripheral side of the second groove 11 and fed to the second groove 11, the second groove 11 is curled by slidingly contacting the bottom surface 11A of the second groove 11 and receiving frictional resistance.

Here, the curl diameter of the chip K guided in the second groove 11 is determined by the easiness of curl of the chip K itself and the radius of curvature r of the bottom surface 11A of the second groove 11, If the latter radius of curvature r is too large, the chips K will not be sufficiently curled and will not be divided. On the contrary, if the curvature radius r of the bottom surface 11a of the second groove 11 is too small,
The chips K are rapidly and forcibly curled to a small diameter, so that they are broken in the middle of the curl, which impairs the dischargeability and results in chip clogging. On the other hand, chip K
Is preferably curled in the state that it is housed in the chip discharge groove 2 as shown in FIG. 4, and if it is curled with a diameter larger than this, the chip K hits the inner peripheral surface of the machining hole and rubs, This causes an increase in cutting resistance, damages the machined surface to deteriorate surface accuracy, or hinders smooth cutting of chips. However, in order for the chips K to be curled in the state where they are stored in the chip discharge groove 2, the chips K
The curl diameter must be equal to or less than the diameter R of the circle E _R that is inscribed in the inner circumference circle of the machined hole, that is, the circle E _D in the outer diameter of the drill and the circle E _T formed by the drill core thickness portion 13.

On the other hand, in the drill having the above structure, the bottom surface 11A of the second groove 11 is considered in consideration of the material of the processed material, the thickness of the chips K, the easiness of curling of the chips K itself due to the outflow speed and the like. The radius of curvature r of is 0.9 with respect to the radius R of the circle E _R.
By setting × R to 1.2 × R, it is possible to curl the chip K sufficiently without sliding it against the inner peripheral surface of the machined hole while maintaining the chip discharging property while avoiding the rapid and forced curl. ,
It enables the reliable division. That is, by setting the radius of curvature r of the bottom surface 11A of the second groove 11 to be 0.9 × R or more with respect to the radius R of the circle E _R , the chips K are forcibly and rapidly curled. It is possible to prevent the chips K from being broken on the way, maintain a good chip discharging property, and avoid the occurrence of chip clogging. On the other hand, the radius of curvature r is 1.2 with respect to the radius R of the circle E _R.
By setting it to be less than or equal to × R, it is possible to efficiently curl the chips K by efficiently curling the chips K without slidingly contacting the inner peripheral surface of the processed hole, and promoting efficient chip disposal.

Further, on the heel 9 side of the chip discharging groove 2 on the side opposite to the first groove 10 with the second groove 11 interposed therebetween, the bottom surface of the second groove 11 in a cross section orthogonal to the axis O. Third groove 1 with bottom surface 12A intersecting 11A at an obtuse angle
2 is formed. Therefore, in the above drill,
It is possible to avoid forming a thinned portion between the second groove 11 that curls the chips K and the heel 9 on the outer periphery of the drill body 1, and the chips K may be slidably contacted with the second grooves 11. It is possible to prevent chipping or the like from occurring near the heel 9 when curled. Also, such a third groove 12
By forming the holes, the cutting oil supplied at the time of drilling passes through the third groove 12 in the chip discharge groove 2 and the cutting edge 4
Since it easily enters the side, it is possible to further improve the dischargeability of the chips K, and it is possible to efficiently cool and lubricate the cutting edge 4 and prevent welding or the like from occurring.

In the drill having the above construction, the width W ₃ of the third groove 12 is 0.03 × D to the outer diameter D of the drill.
Although it is set within the range of 0.2 × D, when the width W ₃ of the third groove 12 is less than 0.03 × D, the third groove 12 becomes too narrow and the above-mentioned effect is obtained. This is because there is a risk of disappearing. On the contrary, when the width W ₃ exceeds 0.2 × D, the width of the second groove 11 becomes relatively narrow and the area in which the chip K slides is reduced, so that the chip K is sufficiently curled. There is a risk that the friction resistance sufficient to cause the cutting will not be given and the chip-dividing property will be impaired.

As described above, according to the drill having the above structure,
The cutting blade 4 is composed of the first and second cutting blades 6 and 7, and the chip discharge groove 2 connected to the base end side of the cutting blade 4 is the first,
By comprising the second and third grooves 10, 11 and 12, the cutting blade 4 and the drill body 1 are secured in strength while giving a sharp cutting edge to the cutting blade 4 and maintaining a good chip discharging property. However, it becomes possible to curl the chips K sufficiently and efficiently divide and process them. As a result, a versatile drill that can handle not only general steel drilling but also drilling of high hardness materials such as various alloys, soft materials such as aluminum, or high hardness thin materials It becomes possible to provide.

In addition to this, in the drill of the present embodiment, when viewed from the front end in the direction of the axis O, a virtual straight line F passing through the center of the drill rotation C and extending in a direction perpendicular to the first blades 6 and 6,
The distance S between the straight line G that extends parallel to the virtual straight line F and that is in contact with the concave curve formed by the bottom surface 11A of the second groove 11 is
The outer diameter D of the drill is 0.1 × D or less. However, when the straight line G is located on the front side in the drill rotation direction with respect to the virtual straight line F, that is, when the groove bottom Q of the second groove 11 is deeper than the virtual straight line F, the distance S therebetween is S. Is too large, the groove depth of the second groove 11 becomes deep,
Therefore, the chips K introduced from the first groove 10 are not sufficiently contacted with the bottom surface 11A of the second groove 11, and the chips K
Curl may be hindered. On the other hand, conversely, as shown in FIG. 1, when the straight line G is located on the rear side in the drill rotation direction with respect to the virtual straight line F, that is, the groove bottom Q of the second groove 11 is at a position shallower than the virtual straight line F. In this case, if the distance S is too large, the groove depth of the second groove 11 also becomes shallow, which causes a problem that curled chips K are difficult to be discharged.

Therefore, in this embodiment, the distance S between the virtual straight line F and the straight line G is set to 0.1 × D as described above,
By preventing the groove depth of the second groove 11 from becoming too deep or too shallow, it is possible to more reliably achieve both maintenance of chip discharge performance and efficient chip separation. Of. Therefore, by adopting such a configuration, it becomes possible to perform more stable chip disposal, and it is possible to promote smoother drilling.

By the way, the chips produced by the cutting blade 4 of the drill having such a structure are
It flows out in a fan shape with a radius of D / 2 centering on the center of rotation C of the drill at the tip of the drill, and as described above, the chip discharge groove 2
The first groove 10 guides and curls the second groove 11. That is, the generated chips draw a fan-shaped locus along the arc of the virtual circle E _C shown in FIG.
Will be introduced in. However, if the chips thus introduced into the chip discharge groove 2 make sliding contact only with the inner peripheral side portion of the second groove 11, the chips and the bottom surface 11 of the second groove 11 are in contact.
The area of sliding contact with A becomes small, which may make it difficult to curl the chips sufficiently and efficiently divide them.

Therefore, in the drill of the present embodiment, as shown in FIG. 2, in the side view of the drill from a direction orthogonal to the axis O and the first cutting edge 6, the drill rotation center C at the tip of the drill body 1 is centered, A virtual circle E _C having a diameter equal to the outer diameter D of the drill, that is, a radius D / 2 is drawn, and the virtual circle E _C and the second or third groove 11, 12 of the chip discharge groove 2 in the side view described above.
When the intersection point P with the tip side ridge line portions 14 and 15 is projected on the tip side ridge line portions 14 and 15 of the second or third grooves 11 and 12 in the axis O direction tip view, the axis line O direction tip view. In the above, the projected position of the intersection point P is arranged on the outer peripheral side of the drill outer diameter D from the drill rotation center C with respect to D / 3. That is, the projected intersection point P is the center of rotation of the drill C when viewed from the front end in the direction of the axis O.
Is arranged on the outer peripheral side of a circle E _O having a diameter of ⅔ × D, and by adopting such a configuration, the chips guided to the chip discharge groove 2 and the second chip. Groove 1
The sliding contact area with 1 is ensured sufficiently.

That is, as described above, the chips draw a fan-shaped locus along the virtual circle E _C in the side view of the drill,
The intersection P in this side view shows the position where the outer peripheral edge of the generated chips hits the ridge line portions 14 and 15 on the tip side of the second or third groove 11 and 12, and this is the tip side in the axis O direction. When viewed from above, the chips are slidably in contact with the portions of the grooves 11 and 12 on the inner peripheral side of the position of the intersection P projected on the ridge portions 14 and 15. Therefore, if the position of the intersection point P projected in the front end view in the direction of the axis O is arranged on the outer peripheral side of the circle E _O , the guided chips are removed by the second groove 11.
It is possible to ensure a sufficient contact area between the two by sliding over substantially the entire bottom surface 11A, and the chip dividing effect by the second groove 11 can be more reliably achieved. On the contrary, the position of the intersection point P in the front end view is the circle E _O.
If it is on the inner peripheral side, the guided chips may not be sufficiently slidably contacted with the second groove 11.

As described above, depending on the inclination of the thinning surface 5 and the like, the intersection point P in the side view of the drill is not on the ridge line portion 14 of the second groove 11 but on the ridge line portion 15 of the third groove 12.
Although it may be positioned above, in such a case, the guided chips contact the entire bottom surface 11A of the second groove 11 and make sliding contact therewith. If the position of the intersected point P is on the outer peripheral side of the circle E _O , the curl of the chips is not hindered.

Next, the more preferable length L of the first blade 6 is
The protrusion amount δ of the second cutting edge 7 and the radius of curvature φ near the top H,
The radius of curvature r of the bottom surface 11A of the second groove 11, the second groove 11
The depth (the distance S between the virtual straight line F and the straight line G), the core thickness T, and the core rising amount B will be described according to the type of the processed material. However, the depth of the second groove 11, that is, the distance S, is negative when the straight line G is on the virtual rotation line F side in the drill rotation direction, and conversely, the straight line G is behind the virtual straight line F on the drill rotation direction side. A certain case is positive. First, in the case of drilling a general steel material, the length L of the first cutting blade 6 is set to about 0.3 × D, and the protrusion amount δ and the radius of curvature φ of the second cutting blade 7 are set to 0.3. 02xD to 0.04xD and 0.3
The radius of curvature r of the second groove 11 is about xD to 0.4xD.
Is 1.2 with respect to the radius R of the circle E _R which is inscribed in the drill outer diameter circle E _D and which is inscribed in the circle E _T of the drill core thickness portion 13.
The depth (distance S) of the second groove 11 should be approximately −R.
It is about 0.1 × D, and the core thickness T is 0.25 × D to 0.2.
It is preferable that the center rising amount B is set to 3 × D and the center rising amount B is set to 0.12 × D to 0.15 × D. With such a setting, while the strength of the cutting edge 4 is sufficiently maintained, it is possible to cope with the enlargement of chips due to spring back and the like, and it is possible to obtain good cutting performance.

In the case of drilling a high hardness material, the length L of the first cutting edge 6 is set to about 0.25 × D, and the protrusion amount δ and the curvature radius φ of the second cutting edge 7 are set to 0, respectively. 0.01 x D to 0.0
2 × D and 0.4 × D to about 0.5 × D, the second groove 1
The radius of curvature r of 1 is about 0.9 × R with respect to the radius R, the depth (distance S) of the second groove 11 is about + 0.1 × D, and the core thickness T is 0.3 × D. ~ 0.35 x D, the amount of core rise B
Is preferably set to 0.15 × D to 0.18 × D. That is, in the case of a high hardness material, the chips are relatively easy to be divided into small pieces, and the expansion of the chips after cutting is small. Therefore, the setting is mainly made to secure the strength of the cutting edge 4 and the strength of the drill body 1 in this way. Good to do. Furthermore, in the case of a soft material such as an aluminum material, the length L of the first cutting blade 6 is set to 0.4.
The projection amount δ and the curvature radius φ of the second cutting edge 7 are about 0.03 × D to 0.05 × D and 0.15 × D, respectively.
˜0.3 × D, the radius of curvature r of the second groove 11 is about 0.9 × R with respect to the radius R, the distance S is 0, and the core thickness T is 0.1 × D. It is preferable to set the center rising amount B to 0.15 × D and to 0.05 × D to 0.08 × D. In the case of a soft material, it is preferable that the cutting is easy, and the material hardness is also set so that sharpness is important.

Further, in the case of drilling a high hardness thin material having a high hardness but a low strength of the processed material itself, the length L of the first cutting blade 6 is set to about 0.2 × D, The protrusion amount δ and the radius of curvature φ of the cutting edge 7 are each 0.01 × D to 0.0.
2 × D and 0.4 × D to about 0.5 × D, the second groove 1
The radius of curvature r of 1 is about 0.9 × R with respect to the radius R, the distance S is about + 0.1 × D, and the core thickness T is 0.2 × D.
0.25 x D, the amount B of the core rise is 0.15 x D to 0.18
It is preferably xD. In drilling such a high-hardness thin-walled material, sufficient cutting edge strength that can withstand cutting of a high-hardness material and low cutting resistance required for cutting a thin-walled material, that is, sharp sharpness is required. Therefore, it is desirable to adopt such a setting.

[0039]

As described above, according to the present invention,
The cutting edge is composed of a first cutting edge and a second cutting edge, and while the cutting edge strength is secured by the first cutting edge, the second cutting edge has a convex curved shape protruding more than the first cutting edge. Thus, it is possible to reduce the cutting resistance while maintaining the sharp cutting edge as a whole.
In addition to this, by constructing the chip discharge groove from the first, second, and third grooves, the mutual action of each groove allows the chips to be sufficiently curled while maintaining good chip discharge performance. This makes it possible to more efficiently divide and process chips. As a result, a versatile drill that can handle not only general steel drilling but also drilling of high hardness materials such as various alloys, soft materials such as aluminum, or high hardness thin materials It becomes possible to provide.

[Brief description of drawings]

FIG. 1 is a view of a drill as viewed from the front end in the direction of the axis O showing an embodiment of the present invention.

FIG. 2 is a side view of the drill in the direction of arrow X in FIG.

3 is a cross-sectional view orthogonal to the axis O of the embodiment shown in FIG.

4 is a cross-sectional view showing a state in which a chip K is curled according to the embodiment shown in FIG.

[Explanation of symbols]

1 Drill Main Body 2 Chip Discharge Groove 3 Tip Relief Surface 4 Cutting Edge 5 Thinning Surface 6 First Blade 7 Second Cutting Edge 8 Margin 9 Heel 10 First Groove 11 Second Groove 12 Third Groove 10A, 11A, 12A First, second, third groove 10
Bottom surface of 12 13 Core thickness portion 14 Tip side ridge line portion of second groove 11 (ridge line portion intersecting with thinning surface 5) 15 Tip edge side ridge line portion of third groove 12 (cross ridge portion intersecting with thinning surface 5) O The axis of rotation of the drill C The center of rotation of the tip of the drill D The outer diameter of the drill L The length of the first cutting edge B The amount of centering of the first cutting edge H The vertex of the second cutting edge 7 The amount of protrusion of the second cutting edge 7 φ Curvature radius of the second cutting edge W ₁ Width of the first groove 10 W ₃ Width of the third groove 12 E _D Drill outer diameter circle E _T Circle formed by the core thickness portion E _R Drill outer diameter circle E _D drill rotation center C of the street first change to the radius of curvature a axis O direction leading end view of the radius r bottom 11A of the second groove 11 of the circle R circle E _R inscribed in the circle E _T of core thickness portion 13 with inscribed in Straight line parallel to blades 6 and 6 Straight line A passing through the drill rotation center C in the O-axis O direction tip view
A virtual straight line G that is orthogonal to the second groove 1 that is parallel to the virtual straight line F when viewed in the O-axis end direction
Straight line S passing through groove bottom Q of No. 1 Distance between virtual straight line F and straight line G (depth of second groove 11) E _C Virtual circle of diameter D centered on drill rotation center C in side view of drill P Virtual circle E _C and ridge 14 and 1 in side view of drill
Intersection with 5 E _O A circle with a diameter of 2/3 × D centered on the center of rotation C of the drill when viewed in the direction of the _O axis

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Inoue 1528, Nakashinda, Yokoi, Kobe, Anpachi-gun, Gifu Prefecture Mitsubishi Materials Corporation Gifu Works

Claims (5)

[Claims] 1. A chip discharge groove is formed on a side surface of a drill body rotated around an axis from a tip end toward a base end side, and a ridge line intersecting a bottom surface of the chip discharge groove and a tip flank of the drill body. Is formed with a cutting edge that faces the direction of rotation of the drill, and the cutting edge has a length of 0.2 × D to 0.4 × D with respect to the outer diameter D of the drill in the axial direction tip view, and the outer circumference of the drill. From the inner peripheral end of this first blade extending linearly from the inner peripheral side toward the inner peripheral side, and from the inner peripheral end of this first blade toward the inner peripheral side in the drill rotation direction than the above first blade It is composed of a second cutting edge that reaches the center of rotation of the drill after drawing a protruding convex curve, and the amount of projection of this second cutting edge with respect to the first cutting edge is 0.01 with respect to the drill outer diameter D. It is set in the range of × D to 0.05 × D, while the chip discharge groove is formed in a cross section orthogonal to the axis. Te,
It is composed of first, second, and third grooves having bottom surfaces that are concavely curved and arranged in order from the margin side to the heel side. The first groove is a ridge line portion where the bottom surface of the groove and the tip flank face intersect. And the width of the third groove is set in the range of 0.03 × D to 0.2 × D with respect to the drill outer diameter D, and the second groove is further formed. The radius of curvature of the bottom surface is set within the range of 0.9 × R to 1.2 × R with respect to the radius R of the circle inscribed in the outer diameter circle of the drill and circumscribed in the thick core portion of the drill. Characteristic drill. 2. The amount of centering of the first cutting edge is set in the range of 0.05 × D to 0.2 × D with respect to the drill outer diameter D. The drill according to 1. 3. A radius of curvature of a convex curve drawn by the second cutting edge is set in a range of 0.15 × D to 0.5 × D with respect to the outer diameter D of the drill in the axial tip view. The drill according to claim 1 or 2, wherein 4. A virtual straight line extending in a direction perpendicular to the first cutting edge passing through the drill rotation center in the axial direction end view, and a bottom surface of the second groove extending parallel to the virtual straight line. 4. The drill according to claim 1, wherein the distance between the straight line tangent to the concave curve and the outer diameter D of the drill is 0.1 × D or less. 5. An imaginary circle having a diameter equal to the outer diameter D of the drill is drawn around a drill rotation center at the tip of the drill body in a side view of the drill from a direction orthogonal to the axis and the first blade, The intersection of this virtual circle and the tip side ridge line portion of the second or third groove of the chip discharge groove in the side view is on the tip side ridge line portion of the second or third groove in the axial direction tip view. When projected on the axial direction, the projected position of the intersection is located on the outer peripheral side of the drill outer diameter D with respect to the drill outer diameter D from the center of rotation of the drill. The drill according to any one of claims 1 to 4.