drill

Abstract

This invention provides a drill that can stably supply coolant near the margin, thereby suppressing margin damage. [Solution] A drill centered on a rotation axis O, comprising: a chip evacuation groove 104 extending from the tip surface 3 of the drill toward the rear end in the axial direction; a cutting edge 7 positioned on the ridge of the chip evacuation groove 104 where the surface facing the drill rotation direction T around the rotation axis O connects to the tip surface 3; a margin 81 positioned on the outer circumferential surface 8 of the drill and connected to the surface of the chip evacuation groove 104 facing the drill rotation direction T; and a coolant hole 105 extending inside the drill, wherein the coolant hole 105 has a margin outlet 105u opening into the margin 81.

Description

Technical Field

[0001] The present invention relates to a drill.

Background Art

[0002] As a conventional drill, there is known a configuration including a chip discharge groove extending from the tip surface of the drill toward the rear end side in the axial direction, a cutting edge disposed at a ridge portion where the surface facing the drill rotation direction and the tip surface in the chip discharge groove are connected, a margin disposed on the outer peripheral surface of the drill and connected to the surface facing the drill rotation direction of the chip discharge groove, and a coolant hole extending inside the drill.

[0003] Also, for example, a tip-exchangeable drill described in Patent Document 1 is known. The tip-exchangeable drill includes a steel holder, a cemented carbide drill head detachably attached to the tip of the holder, and a clamp screw for fixing the drill head to the holder. In recent years, this type of tip-exchangeable drill has attracted attention from the viewpoints of reducing tool costs due to tungsten reduction and reducing environmental impact.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Generally, in the drilling of workpieces made of stainless steel, heat-resistant steel, etc., the processed hole tends to shrink due to the increase in cutting heat, so the load on the margin that rubs against the inner peripheral surface of the processed hole tends to increase. For this reason, damage to the margin is likely to occur.

[0006] In particular, margin damage is more pronounced in replaceable-tip drills with large drill bit diameters. Note that in this specification, stainless steel and heat-resistant steel may be replaced with stainless alloys and heat-resistant alloys.

[0007] The present invention aims to provide a drill that can stably supply coolant to the margin and the outer circumference of the cutting edge (hereinafter sometimes referred to as the margin vicinity), thereby suppressing damage to the margin. [Means for solving the problem]

[0008] To solve the above problems, the present invention provides the following means.

[0009] [Aspect 1 of the present invention] A drill centered on a rotating axis, comprising: a chip evacuation groove extending from the tip surface of the drill toward the rear end in the axial direction; a cutting edge disposed on the ridge portion of the chip evacuation groove where the surface facing the direction of drill rotation around the rotating axis connects to the tip surface; a margin disposed on the outer circumferential surface of the drill and connected to the surface of the chip evacuation groove facing the direction of drill rotation; and a coolant hole extending inside the drill, wherein the coolant hole has a margin outlet opening into the margin.

[0010] In the drill of the present invention, the coolant hole has a margin outlet. Therefore, the coolant ejected from the margin outlet can efficiently cool the margin and the inner circumferential surface of the machined hole in the workpiece (hereinafter sometimes referred to as the area near the margin). Since the amount of coolant supplied to the area near the margin can be increased, cutting heat near the margin can be effectively removed (reduced), and margin damage can be suppressed.

[0011] In particular, when drilling holes in workpieces made of stainless steel, heat-resistant steel, etc., which are prone to shrinkage due to rising cutting heat, the present invention makes it possible to minimize the load on the margin that rubs against the inner circumferential surface of the machined hole. As a result, defects such as premature welding to the margin or margin loss are suppressed.

[0012] As described above, the present invention allows for a stable supply of coolant to the margin, thereby suppressing damage to the margin. In particular, even when the present invention is applied to an indexable drill with a large drill diameter, where the peripheral speed of the margin located at the outermost circumference of the drill tends to be high, the load on the margin can be effectively reduced, preventing damage to the margin. This extends tool life, reduces tool costs, and contributes to reducing environmental impact.

[0013] [Aspect 2 of the present invention] The drill according to embodiment 1, wherein the margin comprises a first margin portion arranged adjacent to the margin nozzle in the direction of drill rotation, and a second margin portion arranged adjacent to the margin nozzle on the opposite side of the direction of drill rotation.

[0014] In the above configuration, the first margin portion and the second margin portion come into contact with the inner circumferential surface of the machined hole in the workpiece during drilling. For example, in the case of a two-flute drill, the first and second margin portions are provided in pairs (two sets) spaced apart from each other in the circumferential direction, so the drill is supported at four points with respect to the inner circumferential surface of the machined hole during drilling. As a result, the excellent effects described above can be obtained from the margin nozzles, while the accuracy of the drilling process can be further improved.

[0015] [Aspect 3 of the present invention] The drill according to embodiment 1 or 2, wherein the margin nozzle is positioned away from the ridge portion where the tip surface and the margin are connected, toward the rear end in the axial direction.

[0016] In this case, the margin nozzle is positioned away from the ridge (shoulder) where the drill tip surface and the margin are connected, towards the rear end in the axial direction. Therefore, the above-mentioned effects are obtained by the margin nozzle while ensuring the strength of the shoulder.

[0017] [Aspect 4 of the present invention] The drill according to any one of embodiments 1 to 3, wherein the margin nozzle extends radially outward in the direction of the drill rotation.

[0018] [Aspect 5 of the present invention] A drill according to any one of embodiments 1 to 4, wherein the outer circumferential surface of the drill is provided with a secondary beveling surface located adjacent to the margin in the direction opposite to the drill rotation direction and radially inward from the margin, the coolant hole is groove-shaped and recessed radially inward from the margin, and has a communication channel that connects the margin outlet with the tip surface, the secondary beveling surface, or the chip discharge groove.

[0019] In this case, the coolant flowing through the margin nozzle can also be supplied to the drill tip surface, the secondary beveling surface, or the chip evacuation groove through the connecting passage. When the connecting passage connects the margin nozzle and the drill tip surface, coolant can be stably supplied to the drill tip surface, so cutting heat near the cutting area during drilling (such as the bottom of the hole and the cutting edge of the workpiece) is efficiently removed, and the cooling efficiency is improved. Also, when the connecting passage connects the margin nozzle and the secondary beveling surface, coolant can be supplied to the secondary beveling surface, so the margin adjacent to the secondary beveling surface and the inner circumferential surface of the hole can be efficiently cooled and lubricated. Furthermore, when the connecting passage connects the margin nozzle and the chip evacuation groove, chip evacuation can be improved by directing the coolant flowing through the margin nozzle to the chip evacuation groove through the connecting passage.

[0020] [Aspect 6 of the present invention] Provided is a drill according to any one of Aspects 1 to 5, comprising a chamfered surface that is disposed adjacent to the margin on the outer peripheral surface of the drill in the direction opposite to the drill rotation direction and is located radially inward of the margin, and the coolant hole has a chamfered surface jet outlet that opens to the chamfered surface.

[0021] In this case, since the coolant hole has a chamfered surface jet outlet, the coolant ejected from the chamfered surface is efficiently supplied to the vicinity of the margin on the outer peripheral surface of the drill as the drill rotates. Therefore, the cooling efficiency in the vicinity of the margin is further enhanced.

[0022] 〔Aspect 7 of the present invention〕 The drill according to Aspect 6, wherein the chamfered surface jet outlet extends in the drill rotation direction as it goes radially outward.

[0023] In this case, since the chamfered surface jet outlet extends in the drill rotation direction as it goes radially outward, the coolant ejected from the chamfered surface jet outlet is likely to stay on the outer peripheral surface of the drill. Thereby, the cooling efficiency in the vicinity of the margin is further enhanced.

[0024] 〔Aspect 8 of the present invention〕 The drill according to any one of Aspects 1 to 7, wherein the coolant hole has a tip surface jet outlet that opens to the tip surface.

[0025] In this case, since the coolant hole has a tip surface jet outlet, the coolant ejected from the tip surface jet outlet is efficiently supplied to the tip surface of the drill. Thereby, the cutting heat in the vicinity of the cutting portion during drilling is efficiently removed, and the cooling efficiency is enhanced.

[0026] 〔Aspect 9 of the present invention〕 The drill according to any one of Aspects 1 to 8, wherein in a cross-sectional view perpendicular to the rotation axis, the connection portion between the margin jet outlet and the margin forms an obtuse angle.

[0027] In this case, in a cross-sectional view of the drill, the connection between the margin nozzle and the margin is obtuse, so the above-mentioned effects are obtained by the margin nozzle while the strength of the connection is increased.

[0028] [Aspect 10 of the present invention] A drill according to any one of embodiments 1 to 9, comprising: a holder extending axially along the rotation axis; a drill head detachably attached to a drill head mounting seat located at the axial end of the holder; and a clamp screw for fixing the drill head to the drill head mounting seat.

[0029] The drill with the above configuration is an indexable drill. When the present invention is applied to an indexable drill, where the drill bit diameter is large and the peripheral speed of the margin located at the outermost circumference of the drill tends to be high, the effect of suppressing damage to the margin becomes particularly remarkable. [Effects of the Invention]

[0030] According to the above-mentioned aspect of the present invention, a drill is provided that can stably supply coolant near the margin, thereby suppressing damage to the margin. [Brief explanation of the drawing]

[0031] [Figure 1] Figure 1 is a perspective view showing a replaceable-tip drill according to this embodiment. [Figure 2] Figure 2 is a front view showing a replaceable-tip drill according to this embodiment. [Figure 3] Figure 3 is a side view showing a part of the replaceable-tip drill according to this embodiment. [Figure 4] Figure 4 is a cross-sectional view (longitudinal section) showing the section IV-IV in Figure 2. [Figure 5] Figure 5 is a perspective view showing a part of the holder. [Figure 6] Figure 6 is a perspective view showing the drill head. [Figure 7]Figure 7 is a perspective view showing the drill head. [Figure 8] Figure 8 is a cross-sectional view of the drill head, specifically showing the section VIII-VIII in Figure 3. [Figure 9] Figure 9 is a side view showing the drill head of the first modified example. [Figure 10] Figure 10 is a cross-sectional view (side view) showing a part of the drill head of the second modified example. [Figure 11] Figure 11 is a cross-sectional view (side view) showing a part of the drill head of the third modified example. [Figure 12] Figure 12 is a front view showing a fourth modified example of an interchangeable-tip drill. [Figure 13] Figure 13 is a side view showing a part of a fourth modified example of an interchangeable-tip drill. [Figure 14] Figure 14 is a perspective view showing the drill head of the fourth modified example. [Figure 15] Figure 15 is a perspective view showing the drill head of the fourth modified example. [Figure 16] Figure 16 is a cross-sectional view (longitudinal section) of the drill head of the fourth modified example, specifically showing the XVI-XVI section of Figure 12. [Figure 17] Figure 17 is a cross-sectional view (cross-sectional view) of the drill head of the fourth modified example, specifically showing the XVII-XVII section of Figure 12. [Figure 18] Figure 18 is a cross-sectional view (transverse view) of the drill head of the fourth modified example, specifically showing the XVIII-XVIII section of Figure 13. [Figure 19] Figure 19 is a perspective view showing the drill head of the fifth modified example. [Figure 20] Figure 20 is a perspective view showing the drill head of the fifth modified example. [Figure 21] Figure 21 is a front view showing the drill head of the fifth modified example. [Figure 22] Figure 22 is a cross-sectional view (longitudinal section) showing the XXII-XXII section of Figure 21. [Figure 23]Figure 23 is a cross-sectional view (cross-sectional plan view) of the drill head of the fifth modified example, specifically showing the XXIII-XXIII section of Figure 22. [Modes for carrying out the invention]

[0032] An interchangeable-tip drill 100 and drill head 10 according to one embodiment of the present invention will be described with reference to Figures 1 to 8. The interchangeable-tip drill 100 and drill head 10 of this embodiment are suitable for drilling holes in workpieces made of stainless steel, heat-resistant steel, etc., which tend to generate high cutting heat. In this embodiment, the interchangeable-tip drill 100 and drill head 10 may be simply referred to as a drill or a tool.

[0033] As shown in Figure 1, the replaceable tip drill 100 has a substantially cylindrical shape with a rotation axis O as its center. The replaceable tip drill 100 comprises a shank portion 101, a drilling portion 102, a flange portion 103, a chip evacuation groove 104, and a coolant hole 105. The shank portion 101, the drilling portion 102, and the flange portion 103 are arranged coaxially with respect to the rotation axis O as a common axis. The shank portion 101, the flange portion 103, and the drilling portion 102 are arranged in this order along the direction in which the rotation axis O extends.

[0034] The replaceable-tip drill 100 also includes a substantially cylindrical holder 20 centered on a rotation axis O, a drill head 10 that can be detachably attached to a drill head mounting seat 106 of the holder 20, and a clamp screw 30 that fixes the drill head 10 to the drill head mounting seat 106. The drill head 10 is made of, for example, cemented carbide and constitutes a part (the tip) of the effective drilling portion 102. The holder 20 is made of, for example, steel and constitutes the portion of the effective drilling portion 102 other than the aforementioned part, as well as the flange portion 103 and the shank portion 101.

[0035] [Definition of direction] In this embodiment, the direction in which the rotation axis O of the drill extends is called the axial direction. The rotation axis O is the central axis of the replaceable tip drill 100 and also the central axis of the drill head 10. Of the axial directions, the direction from the shank portion 101 toward the effective drilling portion 102 is called the axial tip side, or simply the tip side, and the direction from the effective drilling portion 102 toward the shank portion 101 is called the axial rear end side, or simply the rear end side.

[0036] Furthermore, the direction perpendicular to the axis of rotation O is called the radial direction. Within the radial direction, the direction approaching the axis of rotation O is called the radially inward direction, and the direction moving away from the axis of rotation O is called the radially outward direction. Furthermore, the direction of rotation around the axis of rotation O is called the circumferential direction. Of the circumferential directions, the direction in which the drill is rotated during drilling is called the drill rotation direction T, and the direction opposite to this is called the opposite direction to the drill rotation direction T or the anti-drill rotation direction.

[0037] [Holder] As shown in Figure 1, the holder 20 extends axially along the rotation axis O. The holder 20 includes a shank portion 101, a flange portion 103, and the portion of the effective drilling portion 102 other than the tip portion (drill head 10).

[0038] The shank portion 101 is columnar in shape, extending axially around the rotation axis O, and is specifically approximately cylindrical. The shank portion 101 is positioned at the rear end of the replaceable-tip drill 100. The shank portion 101 is detachably attached and held to, for example, the spindle of a machine tool (not shown) or the chuck of a drilling machine (hereinafter abbreviated as spindle, etc.). As the shank portion 101 is rotated in the drill rotation direction T by the spindle, etc., and moved toward the tip in the axial direction, the drill cuts into the workpiece and performs drilling.

[0039] The flange portion 103 is positioned in the axial direction between the shank portion 101 and the effective drilling portion 102. The flange portion 103 is the part of the replaceable tip drill 100 with the largest outer diameter. The end face of the flange portion 103 facing the rear end is a flat surface that extends in a direction perpendicular to the rotation axis O and contacts the tip surface of a spindle or the like (not shown). The surface of the flange portion 103 facing the tip is a tapered surface that decreases in diameter towards the tip.

[0040] The effective drilling portion 102 is columnar in shape, extending axially with respect to the rotation axis O. The effective drilling portion 102 includes the tip portion of the holder 20 and the drill head 10. The effective drilling portion 102 cuts into the workpiece by the drill head 10 to perform drilling, and is inserted into the drilled hole during machining.

[0041] The chip evacuation groove 104 opens onto the tip surface (the tip surface 3 of the drill head 10, described later) and the outer circumferential surface of the effective drilling portion 102 and is groove-shaped, extending substantially in the axial direction. The chip evacuation groove 104 extends from the tip surface 3 of the drill head 10 toward the rear end in the axial direction. More specifically, the chip evacuation groove 104 extends substantially spirally toward the opposite side of the drill rotation direction T as it moves from the tip surface 3 toward the rear end. In this embodiment, the chip evacuation groove 104 is arranged across the effective drilling portion 102 and the surface facing the tip side of the flange portion 103. Although not specifically shown, the chip evacuation groove 104 may also be arranged on the outer circumferential surface of the flange portion 103. Note that the chip evacuation groove 104 only needs to be arranged on the effective drilling portion 102 and does not need to be arranged on the flange portion 103.

[0042] The chip evacuation groove 104 has a head chip evacuation groove 104a located at the tip of the chip evacuation groove 104, and a holder chip evacuation groove 104b located in the part of the chip evacuation groove 104 other than the tip. The head chip evacuation groove 104a is the part of the chip evacuation groove 104 located in the drill head 10. The holder chip evacuation groove 104b is the part of the chip evacuation groove 104 located in the holder 20. In the following description, the head chip evacuation groove 104a or the holder chip evacuation groove 104b may be simply referred to as the chip evacuation groove 104.

[0043] Furthermore, multiple chip discharge grooves 104 are provided at intervals from each other in the circumferential direction. As shown in Figure 2, in this embodiment, a pair of chip discharge grooves 104 are provided at equal pitches in the circumferential direction.

[0044] As shown in Figure 5, the coolant hole 105 is formed extending through the inside of the drill. Specifically, the coolant hole 105 extends through the inside of the holder 20 and the inside of the drill head 10. Although not shown in particular, the coolant hole 105 is provided penetrating the replaceable-tip drill 100 in the axial direction. Coolant such as cutting fluid or compressed air is supplied to the coolant hole 105 via a spindle or the like (not shown). The detailed configuration of the coolant hole 105, other than those described above, will be described separately later.

[0045] As shown in Figures 3 to 5, the drill head mounting seat 106 is located at the axial end of the holder 20. The drill head mounting seat 106 has a mounting surface 107 facing the axial end, a support surface 108 that protrudes further towards the end than the mounting surface 107 and faces in the circumferential direction, a fitting hole 109 recessed toward the rear end in the axial direction from the mounting surface 107, and a female screw hole 110 that opens into the mounting surface 107. In other words, the holder 20 has a mounting surface 107, a support surface 108, a fitting hole 109, and a female screw hole 110.

[0046] The mounting surface 107 has a planar shape that extends in a direction perpendicular to the rotation axis O. The support surface 108 faces the drill rotation direction T in the circumferential direction around the rotation axis O. In this embodiment, the support surface 108 is planar. As shown in Figure 5, the support surface 108 extends radially outward toward the drill rotation direction T. Multiple support surfaces 108 are provided at intervals from each other in the circumferential direction. In this embodiment, a pair of support surfaces 108 are provided at equal pitches in the circumferential direction.

[0047] The fitting hole 109 is a bottomed hole centered on the rotation axis O, and specifically, it is a roughly circular hole. The fitting hole 109 is located radially inward from the support surface 108 and opens to the mounting surface 107.

[0048] The female screw hole 110 opens into the mounting surface 107 and extends from the mounting surface 107 toward the rear end in the axial direction. The central axis of the female screw hole 110 extends parallel to the rotation axis O. The female screw hole 110 has a female threaded portion on its inner circumferential surface. Multiple female screw holes 110 are provided spaced apart from each other in the circumferential direction. In this embodiment, a pair of female screw holes 110 are provided at equal pitches in the circumferential direction.

[0049] [Drill head] The drill head 10 is detachably attached to the drill head mounting seat 106 of the holder 20 and is rotated together with the holder 20 in the drill rotation direction T around the rotation axis O by a spindle (not shown).

[0050] As shown in Figures 6 and 7, the drill head 10 has a tip surface 3 facing the axial tip side, an outer peripheral surface 8 facing radially outward, a chip evacuation groove 104 opening on the tip surface 3 and the outer peripheral surface 8 and extending from the tip surface 3 towards the axial rear end, a rake surface 5, a relief surface 6, a cutting edge 7, a seating surface 9, a fitting portion 13, a screw insertion hole 14, and a supported surface 15. In other words, the drill has a cutting edge 7. In this embodiment, the tip surface 3 may be referred to as the drill tip surface 3, the outer peripheral surface 8 as the drill outer peripheral surface 8, and so on.

[0051] The chip evacuation groove 104 of the drill head 10 is specifically the head chip evacuation groove 104a described above. The chip evacuation groove 104 (head chip evacuation groove 104a) extends in the direction opposite to the drill rotation as it moves from the tip surface 3 toward the rear end in the axial direction.

[0052] The chip evacuation groove 104 has a thinning surface 11. The thinning surface 11 is located at the axial tip of the head chip evacuation groove 104a (chip evacuation groove 104) and is connected to the tip surface 3. Specifically, the thinning surface 11 is connected to the end of the tip surface 3 opposite to the drill rotation direction T. The thinning surface 11 extends towards the axial rear end as it is directed away from the drill rotation direction.

[0053] The rake face 5 is located at least at the tip of the chip evacuation groove 104 (head chip evacuation groove 104a) that faces the drill rotation direction T. That is, the chip evacuation groove 104 further has a rake face 5. As shown in Figure 3, the rake face 5 has a thinning rake face 51 and a main rake face 52.

[0054] The thinning rake face 51 is positioned at the radially inner end of the tip of the chip discharge groove 104. The thinning rake face 51 is connected to the radially inner end of the thinning face 11 and faces the drill rotation direction T. In this embodiment, the thinning rake face 51 has a substantially triangular planar shape.

[0055] The main rake face 52 is positioned radially outward from the thinning rake face 51. In this embodiment, the main rake face 52 has a concave curved portion. Of the main rake face 52, the concave curved portion described above has a concave curved shape that is recessed in the direction opposite to the drill rotation when viewed in a cross-sectional view perpendicular to the rotation axis O (i.e., a transverse view).

[0056] As shown in Figure 6, the relief surface 6 is positioned on the tip surface 3. That is, the tip surface 3 has a relief surface 6. The relief surface 6 has a first relief surface 61 and a second relief surface 62 positioned adjacent to the first relief surface 61 in the direction opposite to the drill rotation.

[0057] The first relief surface 61 is connected to the cutting edge 7 and extends axially toward the rear end as it moves away from the cutting edge 7 in the direction opposite to the drill rotation. The second relief surface 62 extends axially toward the rear end as it moves away from the connection point with the first relief surface 61 in the direction opposite to the drill rotation. The first relief surface 61 and the second relief surface 62 are each inclined as described above, thereby providing a relief angle. The second relief surface 62 has a larger relief angle than the first relief surface 61. That is, the amount of axial displacement per unit length along the circumferential direction of the second relief surface 62 (inclination corresponding to the relief angle) is greater than the amount of displacement of the first relief surface 61.

[0058] As shown in Figure 2, in a front view of the drill head 10 viewed from the tip side along the axial direction, the first relief surface 61 is a radially extending band (a roughly polygonal shape that is long in the radial direction), and the second relief surface 62 is roughly fan-shaped.

[0059] In this embodiment, an example was given in which the relief surface 6 has two inclined surfaces (a first relief surface 61 and a second relief surface 62) with different relief angles, but the configuration is not limited to this. The relief surface 6 may be formed by a single inclined surface, or it may have three or more inclined surfaces arranged in the circumferential direction.

[0060] As shown in Figure 6, the cutting edge 7 is positioned on the ridge of the chip evacuation groove 104 (head chip evacuation groove 104a) where the surface facing the drill rotation direction T is connected to the tip surface 3. Specifically, the cutting edge 7 is positioned on the ridge where the rake surface 5 and the flank surface 6 are connected. In other words, the rake surface 5 and the flank surface 6 are each connected to the cutting edge 7. Multiple cutting edges 7 are provided on the drill head 10, i.e., the drill, spaced apart from each other in the circumferential direction. In this embodiment, two cutting edges 7 are provided at equal pitches in the circumferential direction. That is, the drill head 10 and the replaceable tip drill 100 of this embodiment are two-blade twist drills equipped with two cutting edges 7.

[0061] The cutting edge 7 has a thinning edge 71 and a main cutting edge 72. The thinning blade 71 is positioned at the radially inner end of the cutting edge 7. The thinning blade 71 is positioned on the ridge where the thinning rake face 51 and the first relief face 61 are connected. In a front view of the drill shown in Figure 2, the thinning blade 71 extends radially outward from near the rotation axis O, following approximately the radial direction. In this embodiment, the thinning blade 71 is linear. Also, as shown in Figure 3, the thinning blade 71 extends radially outward towards the axial rear end.

[0062] The main cutting edge 72 is positioned radially outward of the thinning edge 71. The main cutting edge 72 is positioned on the ridge where the main rake face 52 and the first relief face 61 are connected. In the front view of the drill shown in Figure 2, the main cutting edge 72 has a concave curved portion that is recessed in the direction opposite to the drill rotation.

[0063] As shown in Figure 3, the main cutting edge 72 extends radially outward towards the axial rear end. The radially inner end of the main cutting edge 72 connects to the radially outer end of the thinning edge 71. As shown in Figure 6, in this embodiment, the connection portion between the main cutting edge 72 and the thinning edge 71 has a convex curved shape that protrudes in the drill rotation direction T. This convex curved portion ensures a smooth connection between the main cutting edge 72 and the thinning edge 71.

[0064] Although not specifically shown in the illustrations, the cutting edge 7 may also have honing positioned at the cutting edge of the cutting edge 7. The honing extends along the direction in which the cutting edge 7 extends (the blade length direction). In this case, the honing may be round honing or chamfer honing.

[0065] The outer surface 8 has a margin 81 and a secondary chamfering surface 82. That is, the drill head 10 and the replaceable tip drill 100 of this embodiment have a margin 81 and a secondary chamfering surface 82.

[0066] The margin 81 is positioned on the outer circumferential surface 8 of the drill head 10 and the replaceable-tip drill 100, and is connected to the surface of the chip evacuation groove 104 facing the drill rotation direction T. The margin 81 is positioned at the end of the outer circumferential surface 8 in the drill rotation direction T and extends substantially in the axial direction. Specifically, as the margin 81 moves toward the rear end in the axial direction, it extends in the direction opposite to the drill rotation direction.

[0067] As shown in Figure 7, the margin 81 and the main rake face 52 are connected to each other via the ridge (leading edge 12). The margin 81 is positioned adjacent to the leading edge 12 in the direction opposite to the drill rotation. The margin 81 is located on a cylindrical rotation trajectory (not shown) obtained by rotating the leading edge 12 around the rotation axis O. In a cross-sectional view perpendicular to the rotation axis O, the margin 81 forms an arc shape centered on the rotation axis O. The leading edge 12 may also have a back taper. In this case, the leading edge 12 is positioned slightly radially inward as it approaches the rear end in the axial direction. The other components of margin 81 will be described separately.

[0068] As shown in Figures 2 and 6, the secondary chamfering surface 82 is positioned adjacent to the margin 81 on the outer peripheral surface 8 in the direction opposite to the drill rotation, and is located radially inward from the margin 81. The circumferential dimension of the secondary chamfering surface 82 is larger than the circumferential dimension of the margin 81. During drilling, the secondary chamfering surface 82 faces the inner circumferential surface of the machined hole in the workpiece with a radial gap between them. The secondary chamfering surface 82 may also be referred to as the outer peripheral clearance portion 82.

[0069] As shown in Figure 7, the seating surface 9 faces the rear end in the axial direction. The seating surface 9 is planar, extending in a direction perpendicular to the axis of rotation O. As shown in Figures 3 and 4, when the drill head 10 is attached to the drill head mounting seat 106, the seating surface 9 contacts the mounting surface 107. This allows the drill head 10 to be supported by the drill head mounting seat 106 from the rear end in the axial direction.

[0070] As shown in Figure 7, the fitting portion 13 protrudes from the seating surface 9 toward the rear end in the axial direction. The fitting portion 13 is columnar in shape with the rotation axis O as its center, and specifically, it is cylindrical in shape that extends in the axial direction. The fitting portion 13 is inserted into the fitting hole 109 of the drill head mounting seat 106 and fitted into place. This positions the drill head 10 radially on the drill head mounting seat 106.

[0071] As shown in Figures 4, 6, and 7, the screw insertion hole 14 penetrates the drill head 10 in the axial direction. The axial tip of the screw insertion hole 14 opens to the tip surface 3, specifically to the second relief surface 62. The axial rear end of the screw insertion hole 14 opens to the seating surface 9. The screw insertion hole 14 is a multi-stage circular hole extending in the axial direction. The inner diameter of the screw insertion hole 14 decreases in stages from the drill tip surface 3 toward the axial rear end. A clamp screw 30 is inserted through the screw insertion hole 14.

[0072] Multiple screw insertion holes 14 are provided at intervals from each other in the circumferential direction. In this embodiment, a pair of screw insertion holes 14 are provided at equal pitches in the circumferential direction. The central axis (not shown) of each screw insertion hole 14 extends in the axial direction. That is, the central axis of each screw insertion hole 14 and the rotation axis O of the drill extend parallel to each other.

[0073] As shown in Figure 4, the screw insertion hole 14 has a large-diameter hole portion 14a located at the front end of the screw insertion hole 14, a small-diameter hole portion 14b located at the rear end of the screw insertion hole 14, and a tapered hole portion 14c located between the large-diameter hole portion 14a and the small-diameter hole portion 14b in the axial direction.

[0074] The large-diameter hole portion 14a is circular in shape and extends axially with respect to the central axis of the screw insertion hole 14. The large-diameter hole portion 14a is the opening on the tip side of the screw insertion hole 14 and opens onto the second relief surface 62 of the drill tip surface 3.

[0075] The small-diameter hole 14b is circular in shape and extends axially around the central axis of the screw insertion hole 14. The inner diameter of the small-diameter hole 14b is smaller than the inner diameter of the large-diameter hole 14a. The small-diameter hole 14b is the opening at the rear end of the screw insertion hole 14 and opens to the seating surface 9.

[0076] The tapered hole portion 14c has a tapered shape centered on the central axis of the screw insertion hole 14, and its inner diameter decreases (reduces in diameter) as it moves toward the rear end in the axial direction. The tip end of the tapered hole portion 14c is smoothly connected to the rear end of the large diameter hole portion 14a. The rear end of the tapered hole portion 14c is smoothly connected to the tip end of the small diameter hole portion 14b. The tapered hole portion 14c constitutes a stepped portion located on the inner circumferential surface of the screw insertion hole 14. A part of the clamp screw 30 (the tapered portion 31b described later) contacts and is locked into the tapered hole portion 14c (stepped portion).

[0077] As shown in Figures 3 and 7, the supported surface 15 is positioned in the circumferential direction between the chip discharge groove 104 (head chip discharge groove 104a) and the secondary beveling surface 82. The supported surface 15 faces the direction opposite to the drill rotation direction around the rotation axis O. In this embodiment, the supported surface 15 is planar. Specifically, the supported surface 15 is polygonal, and in the illustrated example, it is approximately trapezoidal. The supported surface 15 extends radially outward toward the drill rotation direction T.

[0078] Multiple support surfaces 15 are provided at intervals from each other in the circumferential direction. In this embodiment, a pair of support surfaces 15 are provided at equal pitches in the circumferential direction. As shown in Figure 3, the support surfaces 15 contact the support surface 108 of the drill head mounting seat 106, which faces the drill rotation direction T. As a result, the drill head 10 is supported by the drill head mounting seat 106 from the direction opposite to the drill rotation direction.

[0079] [Clamping screws] As shown in Figures 1, 2, and 4, a clamp screw 30 for fastening the drill head 10 and the holder 20 is inserted into the screw insertion hole 14. The clamp screw 30 is inserted into the screw insertion hole 14 and is screwed into the female screw hole 110 of the drill head mounting seat 106 while in contact with the stepped portion (tapered hole portion 14c in this embodiment) located on the inner circumferential surface of the screw insertion hole 14 from the axial tip side. In this way, the drill head 10 is detachably fixed to the drill head mounting seat 106.

[0080] With the clamp screw 30 screwed into the female screw hole 110, the screw axis of the clamp screw 30 (not shown) is approximately aligned with the central axis of the screw insertion hole 14. However, this is not the only option; with the clamp screw 30 screwed into the female screw hole 110, the screw axis of the clamp screw 30 may be positioned slightly in the anti-drill rotation direction relative to the central axis of the screw insertion hole 14. In this case, the clamp screw 30 presses against the stepped portion (tapered hole portion 14c) on the inner circumferential surface of the screw insertion hole 14 in the anti-drill rotation direction, thereby stabilizing the contact between the supported surface 15 of the drill head 10 and the support surface 108 of the drill head mounting seat 106. That is, the mounting state of the drill head 10 to the drill head mounting seat 106 becomes more stable.

[0081] As shown in Figure 4, the clamp screw 30 has a substantially multi-stage cylindrical shape and extends in the axial direction. The clamp screw 30 has a screw head 31 located at the tip of the clamp screw 30 and a screw shaft portion 32 located on the part of the clamp screw 30 other than the tip.

[0082] The screw head 31 is roughly cylindrical and extends in the axial direction. The screw head 31 has the largest outer diameter among the clamp screws 30. The outer diameter of the screw head 31 is smaller than the inner diameter of the large diameter hole portion 14a of the screw insertion hole 14, and larger than the inner diameter of the small diameter hole portion 14b.

[0083] The screw head 31 has a locking hole 31a into which a work tool is locked, and a tapered portion 31b located on the rear end portion of the outer circumferential surface of the screw head 31. The locking hole 31a is concave, recessed from the top surface facing the axial tip side of the screw head 31 toward the rear end. The tapered portion 31b decreases in outer diameter (reduces in diameter) as it is directed toward the rear end in the axial direction. When the clamp screw 30 is inserted through the screw insertion hole 14 and screwed into the female screw hole 110, the tapered portion 31b contacts the tapered hole portion 14c from the axial tip side and from the inside in the diameter direction of the hole perpendicular to the central axis of the screw insertion hole 14.

[0084] The screw shaft portion 32 is roughly cylindrical and extends in the axial direction. The outer diameter of the screw shaft portion 32 is smaller than the outer diameter of the screw head 31. Also, the outer diameter of the screw shaft portion 32 is smaller than the inner diameter of the small diameter hole portion 14b of the screw insertion hole 14. The axial tip of the screw shaft portion 32 is connected to the axial rear end of the screw head 31. The screw shaft portion 32 has a male thread on its outer circumferential surface. The screw shaft portion 32 is screwed into the female screw hole 110.

[0085] [Coolant holes and margins] Here, the coolant holes 105 of this embodiment will be described in detail. The components of the margin 81 will also be described. The coolant hole 105 has a holder flow path 105a extending inside the holder 20 and a head flow path 105b extending inside the drill head 10 and communicating with the holder flow path 105a. That is, the holder 20 has the holder flow path 105a, and the drill head 10 has the head flow path 105b.

[0086] As shown in Figures 1 and 5, the holder channel 105a is located in at least the portion of the holder 20 that constitutes the effective drilling portion 102 (in other words, the portion of the effective drilling portion 102 other than the drill head 10). The holder channel 105a is located between a pair of circumferentially adjacent chip discharge grooves 104 (holder chip discharge groove 104b) in the effective drilling portion 102. The holder channel 105a extends in the direction opposite to the drill rotation as it approaches the rear end in the axial direction.

[0087] In this embodiment, the holder channel 105a extends across the effective drilling portion 102, the flange portion 103, and the shank portion 101, that is, along the entire axial length of the holder 20. The holder channel 105a is provided to penetrate the holder 20 in the axial direction. The axial rear end of the holder channel 105a opens to the rear end face of the shank portion 101. However, this is not limited to this configuration, and although not specifically shown, for example, the holder channel 105a may be located only in the effective drilling portion 102 and the flange portion 103, and the axial rear end of the holder channel 105a may open to the end face facing the rear end of the flange portion 103.

[0088] The holder channel 105a has a plurality of branch channels 105c arranged at intervals from each other in the circumferential direction. Each branch channel 105c is located between adjacent chip discharge grooves 104 in the circumferential direction. In this embodiment, a pair of branch channels 105c are provided at equal pitches in the circumferential direction. The plurality of branch channels 105c merge with each other at the connection portion with the head channel 105b (within the fitting hole 109, described later). Specifically in this embodiment, two branch channels 105c are connected to each other at the axial end of each branch channel 105c.

[0089] Furthermore, the holder channel 105a has multiple linear channels 105d and 105e that extend at an inclination with respect to the rotation axis O. Specifically, in this embodiment, each branch channel 105c has two linear channels 105d and 105e. The multiple linear channels 105d and 105e are arranged side by side in the axial direction and are connected to each other. Of the multiple linear channels 105d and 105e, one linear channel 105d and the other linear channels 105e extend in different directions (i.e., have different inclinations).

[0090] Of the multiple straight channels 105d and 105e, the straight channel 105d located at the very front opens into the fitting hole 109 of the drill head mounting seat 106. Specifically, the axial ends of each straight channel 105d of the pair of branched channels 105c open into the bottom surface and inner circumferential surface of the fitting hole 109, respectively. That is, the holder channel 105a has a holder-side connection port 105f that opens into the fitting hole 109, and the holder-side connection port 105f is located at the front of the straight channel 105d. The straight channel 105d is connected to the head channel 105b via the holder-side connection port 105f.

[0091] Of the multiple straight channels 105d and 105e, the other straight channel 105e located at the rearmost end opens to the rear end face of the shank portion 101. Specifically, the axial rear ends of each of the other straight channels 105e of the pair of branched channels 105c each open to the rear end face of the shank portion 101. That is, the holder channel 105a has a coolant inlet 105g that opens to the rear end face of the shank portion 101, and the coolant inlet 105g is located at the rear end of the other straight channels 105e. Coolant flows into each coolant inlet 105g through the inside of a spindle or the like (not shown). In this embodiment, the inner diameter of one straight channel 105d is smaller than the inner diameter of the other straight channel 105e, which is located further to the rear end than the first straight channel 105d.

[0092] Although not specifically shown in the figures, in addition to the above configuration of this embodiment, the holder channel 105a may have multiple curved channels that extend in a curved shape. The multiple curved channels are arranged in a line in the axial direction and connected to one another. Alternatively, the holder channel 105a may be formed by combining straight channels and curved channels.

[0093] As shown in Figures 6 to 8, the head channel 105b is provided through the drill head 10. The axial end of the head channel 105b (the communication channel 105v, described later) opens to the tip surface 3. The axial rear end of the head channel 105b opens to the rear end surface of the fitting portion 13. In addition, the radially outer end of the head channel 105b opens to the outer circumferential surface 8.

[0094] The head flow path 105b has an introduction flow path 105h connected to the holder flow path 105a for introducing coolant from the holder flow path 105a into the head flow path 105b, and a margin flow path 105t connected to the introduction flow path 105h and opening to the margin 81.

[0095] The introduction channel 105h extends axially inside the drill head 10. The introduction channel 105h is a circular hole centered on the rotation axis O. The axial rear end of the introduction channel 105h is located inside the fitting portion 13 and opens to the rear end surface of the fitting portion 13. The axial rear end of the introduction channel 105h is a head-side connection port 105k that is connected to the holder-side connection port 105f of the holder channel 105a. That is, the head channel 105b has a head-side connection port 105k. In addition, the axial tip of the introduction channel 105h is located away from the tip surface 3 towards the rear end (see Figure 16, etc.). In this embodiment, the bottom of the hole located at the axial tip of the introduction channel 105h is a hemispherical shape that is concave toward the tip.

[0096] The margin channel 105t extends radially outward from the connection point with the introduction channel 105h. As shown in Figure 8, in a cross-sectional view perpendicular to the rotation axis O, the margin channel 105t has a concave curve shape that is recessed in the direction opposite to the drill rotation. Multiple margin channels 105t are provided at intervals from each other in the circumferential direction. In this embodiment, a pair of margin channels 105t are provided at equal pitches in the circumferential direction.

[0097] As shown in Figures 6 and 7, the margin channel 105t has a cross-sectional shape (meaning the shape of the cross-section perpendicular to the direction in which the channel extends, and the same applies hereinafter) that is a slit shape, a polygonal shape such as a flattened rectangle, an oval shape, or an ellipse shape. The axial dimension of the margin channel 105t is larger than the circumferential dimension of the margin channel 105t.

[0098] As shown in Figures 6 to 8, the radial outer end of the margin flow path 105t is a margin outlet 105u that opens into the margin 81. That is, the head flow path 105b (coolant hole 105) has a margin outlet 105u. Multiple margin outlets 105u are provided at intervals from each other in the circumferential direction. In this embodiment, a pair of margin outlets 105u are provided at equal pitches in the circumferential direction.

[0099] The margin nozzle 105u opens between the circumferential ends of the margin 81. The margin nozzle 105u extends along the margin 81, specifically extending in the anti-drill rotation direction as it approaches the axial rear end. The margin nozzle 105u is positioned away from the ridge where the tip surface 3 and the margin 81 are connected, towards the axial rear end. The margin nozzle 105u is also positioned away from the ridge where the seating surface 9 and the margin 81 are connected, towards the axial tip. As shown in Figure 8, the margin nozzle 105u extends radially outward in the direction of drill rotation T.

[0100] Furthermore, as shown in Figures 6 to 8, the margin 81 has a first margin portion 81a positioned adjacent to the margin nozzle 105u in the drill rotation direction T, and a second margin portion 81b positioned adjacent to the margin nozzle 105u on the opposite side of the drill rotation direction T. The first margin portion 81a and the second margin portion 81b each extend in the direction opposite to the drill rotation direction as they are toward the rear end in the axial direction.

[0101] In this embodiment, the first margin portion 81a and the second margin portion 81b are located on the same cylindrical rotational trajectory obtained by rotating the leading edge 12 around the rotation axis O. That is, the radial position of the first margin portion 81a and the radial position of the second margin portion 81b are the same. Furthermore, the circumferential dimension (margin width) of the first margin portion 81a is larger than the circumferential dimension of the second margin portion 81b. Note that the second margin portion 81b may be positioned radially inward of the first margin portion 81a by several tens of micrometers.

[0102] In this embodiment, the head passage 105b (coolant hole 105) is groove-shaped, recessed radially inward from the margin 81, and has a communication passage 105v that connects the margin outlet 105u and the tip surface 3. The communication passage 105v is located adjacent to the margin outlet 105u on the axial tip side of the margin outlet 105u. The communication passage 105v extends in the direction of drill rotation T as it moves axially toward the tip side from the connection point with the margin outlet 105u. In the illustrated example, the circumferential dimension (groove width dimension) of the communication passage 105v is the same as the circumferential dimension (opening width dimension) of the margin outlet 105u. The axial tip of the communication passage 105v opens to the drill tip surface 3.

[0103] [Effects of this embodiment] In the indexable drill 100 and drill head 10 of this embodiment described above, the coolant hole 105 has a margin outlet 105u. Therefore, the coolant ejected from the margin outlet 105u can efficiently cool the margin 81 and the inner circumferential surface of the machined hole in the workpiece (hereinafter sometimes referred to as the area near the margin 81). Since the amount of coolant supplied to the area near the margin 81 can be increased, cutting heat near the margin 81 can be effectively removed (reduced), and damage to the margin 81 can be suppressed.

[0104] In particular, when drilling holes in workpieces made of stainless steel or heat-resistant steel, which are prone to shrinking due to rising cutting heat, this embodiment makes it possible to keep the load on the margin 81 that rubs against the inner circumferential surface of the machined hole to a minimum. As a result, problems such as premature welding to the margin 81 or damage to the margin 81 are suppressed.

[0105] As described above, according to this embodiment, coolant can be stably supplied near the margin 81, thereby suppressing damage to the margin 81. In particular, even when the present invention is applied to an indexable drill 100, which has a large drill diameter and where the peripheral speed of the margin 81 located at the outermost circumference of the drill tends to be high, the load on the margin 81 can be effectively reduced and damage to the margin 81 can be prevented. As a result, tool life can be extended, tool costs can be reduced, and environmental impact can be reduced.

[0106] In this embodiment, the margin 81 has a first margin portion 81a arranged adjacent to the drill rotation direction T of the margin nozzle 105u, and a second margin portion 81b arranged adjacent to the opposite side of the drill rotation direction T of the margin nozzle 105u.

[0107] In the above configuration, the first margin portion 81a and the second margin portion 81b come into contact with the inner circumferential surface of the machined hole in the workpiece during drilling. In the case of a two-blade drill as in this embodiment, the first margin portion 81a and the second margin portion 81b are provided in pairs (two sets) spaced apart from each other in the circumferential direction, so the drill is supported at four points with respect to the inner circumferential surface of the machined hole during drilling. As a result, the excellent effects described above can be obtained with respect to the margin nozzle 105u, while the accuracy of the drilling process can be further improved.

[0108] Furthermore, if the second margin portion 81b is positioned radially inward by several tens of micrometers compared to the first margin portion 81a, the first margin portion 81a will primarily contact the inner circumferential surface of the machined hole, and contact between the second margin portion 81b and the inner circumferential surface of the machined hole will be suppressed. As a result, the contact resistance between the margin 81 and the inner circumferential surface of the machined hole is reduced. In addition, when the drill moves radially within the machined hole due to runout or the like, the second margin portion 81b, along with the first margin portion 81a, will contact the inner circumferential surface of the machined hole, thus maintaining a good machining position for the drill.

[0109] Furthermore, in this embodiment, the margin nozzle 105u is positioned away from the ridge (shoulder) where the drill tip surface 3 and the margin 81 are connected, towards the rear end in the axial direction. Therefore, the above-mentioned effects are obtained by the margin nozzle 105u while ensuring the strength of the shoulder.

[0110] Furthermore, in this embodiment, the margin outlet 105u extends radially outward towards the drill rotation direction T. This prevents the coolant ejected from the margin outlet 105u from immediately flowing in the opposite direction of drill rotation and makes it easier for it to remain near the margin 81. As a result, the cooling efficiency near the margin 81 is further improved.

[0111] In this embodiment, the coolant hole 105 is groove-shaped, recessed radially inward from the margin 81, and has a communication channel 105v that connects the margin outlet 105u and the tip surface 3. In this case, the coolant flowing through the margin outlet 105u can also be supplied to the drill tip surface 3 through the communication channel 105v. Because coolant can be stably supplied to the drill tip surface 3, cutting heat near the cutting area during drilling (such as the bottom of the hole in the workpiece and the cutting edge 7) is efficiently removed, and the cooling efficiency is improved.

[0112] In this embodiment, the holder channel 105a has a holder-side connection port 105f that opens into the fitting hole 109, and the head channel 105b is located inside the fitting portion 13 and has a head-side connection port 105k that is connected to the holder-side connection port 105f.

[0113] In the above configuration, the fitting structure between the fitting hole 109 of the drill head mounting seat 106 and the fitting portion 13 of the drill head 10 is used to connect the holder-side connection port 105f of the holder flow path 105a and the head-side connection port 105k of the head flow path 105b. Therefore, it is easy to position the coolant holes 105 without interfering with the screw insertion holes 14 through which the clamp screws 30 are inserted or the female screw holes 110 into which the clamp screws 30 are screwed, thereby increasing the freedom of drill design.

[0114] In this embodiment, multiple chip discharge grooves 104 are provided spaced apart from each other in the circumferential direction, and the holder flow path 105a has multiple branched flow paths 105c arranged spaced apart from each other in the circumferential direction, each branched flow path 105c is located between adjacent chip discharge grooves 104 in the circumferential direction, and the multiple branched flow paths 105c merge with each other at the connection point with the head flow path 105b.

[0115] In this case, multiple branched passages 105c ensure sufficient coolant flow within the holder 20, and these branched passages 105c are merged at the connection point between the holder passage 105a and the head passage 105b. This makes it easier to suppress interference between the screw insertion hole 14 through which the clamp screw 30 is inserted, the female screw hole 110 into which the clamp screw 30 is screwed, and the coolant hole 105.

[0116] In this embodiment, the holder channel 105a has a plurality of linear channels 105d and 105e that extend at an inclination with respect to the rotation axis O, and the plurality of linear channels 105d and 105e are arranged side by side in the axial direction and connected to each other, and one of the linear channels 105d located at the tip of the plurality of linear channels 105d and 105e is connected to the head channel 105b.

[0117] In this case, the holder channel 105a is formed by connecting multiple straight channels 105d and 105e that are inclined with respect to the rotation axis O. The structure of the holder channel 105a can be simplified, and the manufacturing of the holder 20 becomes easier.

[0118] [Other components included in the present invention] The present invention is not limited to the embodiments described above, and modifications to the configuration, etc., are possible without departing from the spirit of the invention, as described below. In the illustrations of modified examples, the same reference numerals are used for the same components as in the embodiments described above, and the main differences will be described below.

[0119] Figure 9 is a side view showing a drill head 10A, which is a first modification of the drill head 10 described in the above-described embodiment. Although not specifically shown, the drill head 10A is detachably attached to the drill head mounting seat 106 of the holder 20. The drill head 10A constitutes the tip of the effective drilling portion 102 of the replaceable tip drill 100. As shown in Figure 9, the first modification of the drill head 10A differs from the drill head 10 of the above-described embodiment in the configuration of the head flow path 105b.

[0120] Specifically, in this first modified example, the head passage 105b (coolant hole 105) does not have a connecting passage 105v. That is, when a margin outlet 105u is provided, a connecting passage 105v does not need to be provided. According to the first modification described above, the structure of the drill head 10A is simplified, and the strength of the ridge (shoulder) portion to which the drill tip surface 3 and the margin 81 are connected is further increased.

[0121] Figure 10 is a cross-sectional view (horizontal cross-section) showing a part of the drill head 10B of the second modified example. More specifically, Figure 10 shows an enlarged view of the area near the radial outer end of the margin flow channel 105t (near the margin outlet 105u) in a cross-sectional view (horizontal cross-section) perpendicular to the rotation axis O of the drill head 10B.

[0122] In this second modified example, as shown in Figure 10, the connection between the margin nozzle 105u and the margin 81 forms an obtuse angle in a cross-sectional view perpendicular to the axis of rotation O. Specifically, in this cross-sectional view, the connection between the margin nozzle 105u and the first margin portion 81a is formed in a chamfered shape, thus forming an obtuse angle. Furthermore, in this cross-sectional view, the connection between the margin nozzle 105u and the second margin portion 81b is formed in a chamfered shape, thus forming an obtuse angle.

[0123] According to the second modification described above, in a cross-sectional view of the drill, the connection between the margin nozzle 105u and the margin 81 is obtuse, so that the above-mentioned effects can be obtained by the margin nozzle 105u while increasing the strength of the connection.

[0124] Figure 11 is a cross-sectional view (horizontal cross-section) showing a part of the drill head 10C of the third modified example. More specifically, Figure 11 shows an enlarged view of the area near the radial outer end of the margin flow channel 105t (near the margin outlet 105u) in a cross-sectional view (horizontal cross-section) perpendicular to the rotation axis O of the drill head 10C.

[0125] As shown in Figure 11, in this third modification, the head passage 105b, i.e., the coolant hole 105, is groove-shaped, recessed radially inward from the margin 81, and has a communication passage 105w that connects the margin outlet 105u and the second chamfering surface 82. Specifically, the communication passage 105w is groove-shaped, recessed radially inward from the second margin portion 81b, and extends in the circumferential direction. The end of the communication passage 105w in the drill rotation direction T is connected to the margin outlet 105u, and the end of the communication passage 105w in the opposite direction of drill rotation is connected to the second chamfering surface 82.

[0126] In the third modified example described above, the coolant flowing through the margin outlet 105u can also be supplied to the secondary chamfering surface 82 through the communication channel 105w. Because coolant can be supplied to the secondary chamfering surface 82, the margin 81 adjacent to the secondary chamfering surface 82 and the inner circumferential surface of the machined hole can be efficiently cooled and lubricated.

[0127] Furthermore, although not specifically shown in the figures, the head passage 105b, i.e., the coolant hole 105, may have a groove shape that is recessed radially inward from the margin 81, and may have a communication passage that connects the margin outlet 105u and the chip discharge groove 104. Specifically, the communication passage has a groove shape that is recessed radially inward from the first margin portion 81a and extends in the circumferential direction. The end of the communication passage in the drill rotation direction T is connected to the chip discharge groove 104 (head chip discharge groove 104a), and the end of the communication passage in the opposite direction of drill rotation is connected to the margin outlet 105u. In this case, the chip discharge performance can be improved by directing the coolant flowing through the margin outlet 105u to the chip discharge groove 104 through the communication channel.

[0128] Furthermore, although not specifically shown in the figures, the head passage 105b may be connected to the introduction passage 105h and have a secondary chamfer passage that opens to the secondary chamfer (outer peripheral clearance portion) 82. The radial outer end of the secondary chamfer passage is a secondary chamfer outlet (outer peripheral clearance portion outlet) that opens to the secondary chamfer 82. In other words, the head passage 105b (coolant hole 105) may further have a secondary chamfer outlet. Note that a part of the secondary chamfer passage may be connected to the margin passage 105t. The secondary chamfer passage may branch off from the margin passage 105t.

[0129] In this case, since the coolant hole 105 has a secondary beveling surface outlet, the coolant ejected from the secondary beveling surface 82 is efficiently supplied to the vicinity of the margin 81 of the drill outer surface 8 as the drill rotates. As a result, the cooling efficiency near the margin 81 is further enhanced.

[0130] Furthermore, the second cutting surface nozzle may extend radially outward in the direction of drill rotation T. In this case, the coolant ejected from the secondary bevel outlet is more likely to remain on the outer surface 8 of the drill. This further improves the cooling efficiency near the margin 81.

[0131] Figures 12 to 18 show the fourth modified example of the drill head 10D and the replaceable tip drill 100. The drill head 10D is detachably attached to the drill head mounting seat 106 of the holder 20. The drill head 10D constitutes the tip of the effective drilling portion 102 of the replaceable tip drill 100. As shown in Figures 12 to 18, the drill head 10D of the fourth modified example differs from the drill heads 10, 10A, 10B, and 10C described above in the configuration of the head flow path 105b of the coolant hole 105. Note that in Figures 12 to 18, the margin flow path 105t, margin outlet 105u, and communication flow path 105v described above are omitted from the illustration.

[0132] As shown in Figures 12 to 18, in this fourth modification, the head channel 105b (coolant hole 105) has a front surface channel 105i connected to the introduction channel 105h and opening to the front surface 3, and a thinning channel 105j connected to the introduction channel 105h and opening to the thinning surface 11.

[0133] As shown in Figure 16, the tip surface channel 105i is connected to the tip portion of the introduction channel 105h. The tip surface channel 105i extends radially outward from the connection point with the introduction channel 105h toward the tip in the axial direction. Also, as shown in Figure 18, the tip surface channel 105i extends radially outward from the connection point with the introduction channel 105h toward the drill rotation direction T. Multiple tip surface channels 105i are provided at intervals from each other in the circumferential direction. In the illustrated example, a pair of tip surface channels 105i are provided at equal pitches in the circumferential direction.

[0134] The tip surface channel 105i has a cross-sectional shape that is slit-shaped, a polygonal shape such as a flattened rectangle, an oval shape, or an ellipse shape. The radial dimension of the tip surface channel 105i is larger than the circumferential dimension of the tip surface channel 105i. A portion of the tip surface channel 105i may be connected to the margin channel 105t. The tip surface channel 105i may also branch off from the margin channel 105t.

[0135] As shown in Figures 12, 14, and 16, the axial tip of the tip surface flow path 105i is a tip surface nozzle 105m that opens onto the drill tip surface 3. That is, the head flow path 105b (coolant hole 105) has a tip surface nozzle 105m. Multiple tip surface nozzles 105m are provided spaced apart from each other in the circumferential direction. In the illustrated example, a pair of tip surface nozzles 105m are provided at equal pitches in the circumferential direction.

[0136] The tip surface nozzle 105m opens in a region of the tip surface 3 located between the screw insertion hole 14 and the cutting edge 7 around the rotation axis O. Specifically, this region refers to the part of the tip surface 3 located in the direction of drill rotation T of the screw insertion hole 14 and the direction of cutting edge 7 opposite to the drill rotation direction, that is, the part sandwiched between the screw insertion hole 14 and the cutting edge 7 in the circumferential direction.

[0137] More specifically, in the fourth modification, the tip surface nozzle 105m opens across the first relief surface 61 and the second relief surface 62 of the tip surface 3. Furthermore, in the tip surface nozzle 105m, more than half of the opening area of ​​the tip surface nozzle 105m is located on the second relief surface 62.

[0138] As shown in Figure 12, in a front view of the drill with the tip surface 3 viewed from the axial tip side, the tip surface nozzle 105m extends in a direction intersecting the circumferential direction around the rotation axis O. In the illustrated example, the tip surface nozzle 105m extends substantially in the radial direction in a front view of the drill. More specifically, in a front view of the drill, the tip surface nozzle 105m extends towards the drill rotation direction T as it moves radially outward.

[0139] The opening shape of the tip surface nozzle 105m corresponds to the shape of the flow channel cross-section of the tip surface flow channel 105i, and can be a slit shape, a polygonal shape such as a flattened rectangle, an oval shape, or an ellipse shape. The radial dimension of the tip surface nozzle 105m is made larger than the circumferential dimension of the tip surface nozzle 105m.

[0140] In this fourth modification, the radial inner end of the tip surface nozzle 105m is positioned radially outward from the radial inner edge of the tip surface 3 (the boundary between the tip surface 3 and the thinning surface 11, near the axis of rotation O). Also, the radial outer end of the tip surface nozzle 105m is positioned radially inward from the radial outer edge of the tip surface 3 (the ridge portion where the tip surface 3 and the outer peripheral surface 8 are connected).

[0141] As shown in Figure 17, the thinning channel 105j is connected to the axial tip of the introduction channel 105h. The thinning channel 105j extends radially outward from the connection point with the introduction channel 105h toward the axial tip. Also, as shown in Figure 18, the thinning channel 105j extends radially outward from the connection point with the introduction channel 105h toward the anti-drill rotation direction. Multiple thinning channels 105j are provided at intervals from each other in the circumferential direction. In the illustrated example, a pair of thinning channels 105j are provided at equal pitches in the circumferential direction. The tip surface channels 105i and the thinning channels 105j are arranged alternately in the circumferential direction.

[0142] The thinning channel 105j has a cross-sectional shape that is slit-shaped, a polygonal shape such as a flattened rectangle, an oval shape, or an ellipse shape. The radial dimension of the thinning channel 105j is larger than the circumferential dimension of the thinning channel 105j. Also, the radial dimension of the thinning channel 105j is smaller than the radial dimension of the front surface channel 105i. The circumferential dimension of the thinning channel 105j is smaller than the circumferential dimension of the front surface channel 105i. A portion of the thinning channel 105j may be connected to the margin channel 105t. The thinning channel 105j may branch off from the margin channel 105t.

[0143] As shown in Figures 12, 14, and 17, the axial tip of the thinning channel 105j is a thinning outlet 105n that opens onto the thinning surface 11. That is, the head channel 105b (coolant hole 105) has a thinning outlet 105n. Multiple thinning outlets 105n are provided at intervals from each other in the circumferential direction. In the illustrated example, a pair of thinning outlets 105n are provided at equal pitches in the circumferential direction. The tip surface outlets 105m and thinning outlets 105n are arranged alternately in the circumferential direction.

[0144] The thinning nozzle 105n opens at the radial inner end of the thinning surface 11. Specifically, the thinning nozzle 105n opens at the portion of the thinning surface 11 adjacent to the thinning scoop surface 51.

[0145] As shown in Figure 12, in a front view of the drill with the tip surface 3 viewed from the axial tip side, the thinning nozzle 105n extends in a direction intersecting the circumferential direction around the rotation axis O. In the illustrated example, the thinning nozzle 105n extends substantially in the radial direction in a front view of the drill. More specifically, in a front view of the drill, the thinning nozzle 105n extends in the direction opposite to the drill rotation as it moves radially outward.

[0146] The opening shape of the thinning nozzle 105n corresponds to the shape of the flow path cross-section of the thinning flow path 105j, and can be a slit shape, a polygonal shape such as a flattened rectangle, an oval shape, or an ellipse shape. The radial dimension of the thinning nozzle 105n is larger than the circumferential dimension of the thinning nozzle 105n. Also, the radial dimension of the thinning nozzle 105n is smaller than the radial dimension of the tip surface nozzle 105m. The circumferential dimension of the thinning nozzle 105n is smaller than the circumferential dimension of the tip surface nozzle 105m.

[0147] The opening shape of the thinning nozzle 105n is not limited to the above configuration. Although not specifically shown in the diagram, the thinning nozzle 105n may be circular, a regular polygon, or the like when viewed from the front of the drill.

[0148] In the drill head 10D and replaceable tip drill 100 of the fourth modified example described above, the head passage 105b (coolant hole 105) has a tip surface nozzle 105m that opens onto the tip surface 3. Coolant supplied from the holder passage 105a to the head passage 105b is ejected onto the tip surface 3 of the drill head 10 through the tip surface nozzle 105m. As a result, coolant is efficiently supplied to the drill tip surface 3. This efficiently removes (reduces) cutting heat near the cutting area during drilling (such as the bottom of the hole in the workpiece and the cutting edge 7), thereby improving cooling efficiency.

[0149] Furthermore, the tip surface nozzle 105m opens in the region of the drill tip surface 3 between the screw insertion hole 14 and the cutting edge 7 around the rotation axis O. By supplying coolant to the aforementioned area of ​​the drill tip surface 3, it is prevented from immediately flowing out into the chip evacuation groove 104 adjacent to the screw insertion hole 14 in the direction opposite to the drill rotation. As a result, the coolant tends to remain near the drill tip surface 3. In addition, the coolant is ejected from the tip surface nozzle 105m to the part of the drill head 10 tip surface 3 that is close to the cutting edge 7. Therefore, the cutting heat near the cutting area is efficiently removed by the coolant, and the cooling efficiency is improved.

[0150] Furthermore, in the fourth modification described above, there is a high degree of freedom in designing the opening shape and opening area of ​​the tip surface nozzle 105m. For example, in the case of a configuration in which only the entrance portion of the bolt hole (the opening of the screw insertion hole) on the tip surface of the drill is used as the coolant nozzle, as in Patent Document 1 (Patent No. 4703940), the opening shape of this nozzle is circular, and the opening area is based on the diameter dimension of the screw head of the clamp screw, so there is little freedom in the design.

[0151] On the other hand, in the fourth modification described above, the opening shape of the tip surface nozzle 105m can be freely set in the region between the screw insertion hole 14 and the cutting edge 7, for example, to be slit-shaped, oval-shaped, elliptical-shaped, polygonal-shaped, or groove-shaped. Furthermore, there is a high degree of freedom in the opening area and layout of the tip surface nozzle 105m. According to the fourth modification described above, the amount of coolant supplied to the drill tip surface 3 can be increased, and a wider range of coolant supply can be secured.

[0152] Therefore, in the fourth modified example described above, the cooling and lubricating effects of the coolant can be more effectively enhanced depending on the application of the drill and the cutting conditions. For example, even when drilling workpieces of materials that tend to generate a lot of cutting heat during drilling, such as stainless steel and heat-resistant steel, the cutting heat can be efficiently removed and the cooling efficiency can be improved.

[0153] As described above, according to the fourth modified example, coolant can be stably supplied to the tip surface 3 of the drill head 10D, thereby improving cooling efficiency. This extends tool life, reduces tool costs, and contributes to reducing environmental impact.

[0154] Furthermore, in a front view of the drill, with the tip surface 3 viewed from the tip side in the axial direction, the tip surface nozzle 105m extends in a direction that intersects with the circumferential direction around the rotation axis O.

[0155] In this case, the tip surface nozzle 105m extends in a direction intersecting the circumferential direction (i.e., a direction including the radial component) when viewed from the front of the drill. Therefore, the tip surface nozzle 105m can be positioned to avoid the vicinity of the screw insertion hole 14 through which the clamp screw 30 is inserted and the cutting edge 7, while ensuring a large opening area of ​​the tip surface nozzle 105m. This makes it possible to stably increase the amount of coolant supplied to the drill tip surface 3.

[0156] Furthermore, the coolant ejected from the tip surface nozzle 105m is supplied to the drill tip surface 3 over a wide area in the radial direction, and then, as the drill rotates, it is also supplied over a wide area in the circumferential direction. This allows the coolant to spread throughout the entire drill tip surface 3, efficiently removing cutting heat and improving cooling efficiency.

[0157] Furthermore, in the case of the tip surface nozzle 105m, more than half of the opening area of ​​the tip surface nozzle 105m is located on the second relief surface 62.

[0158] In this case, more than half of the opening area of ​​the tip surface nozzle 105m is located on the second relief surface 62, which is away from the cutting edge 7. Therefore, the above-mentioned excellent effects can be obtained from the tip surface nozzle 105m while ensuring the cutting edge strength of the cutting edge 7.

[0159] Furthermore, the head passage 105b (coolant hole 105) has a thinning nozzle 105n that opens onto the thinning surface 11. The coolant ejected from the thinning nozzle 105n is supplied to the thinning blade 71 located at the radially inner end of the cutting edge 7, the thinning rake surface 51 adjacent to the thinning blade 71, and the drill tip surface 3. The thinning blade 71 and the thinning rake surface 51, which tend to have high cutting resistance among the cutting edges 7, can be efficiently cooled by the coolant ejected from the thinning nozzle 105n. This suppresses chipping of the thinning blade 71 and crater wear of the thinning rake surface 51. In addition, it becomes possible to secure a larger amount of coolant supply to the drill tip surface 3, making the above-mentioned effects even more pronounced.

[0160] Figures 19 to 23 show the drill head 10E of the fifth modified example. Although not specifically shown, the drill head 10E is detachably attached to the drill head mounting seat 106 of the holder 20. The drill head 10E constitutes the tip of the effective drilling portion 102 of the replaceable tip drill 100. As shown in Figures 19 to 23, the drill head 10E of the fifth modified example differs from the drill head 10D of the fourth modified example in the configuration of the head flow path 105b. Note that in Figures 19 to 23, the margin flow path 105t, margin outlet 105u, and communication flow path 105v, etc., described above are omitted from the illustration.

[0161] Specifically, in this fifth modification, the head passage 105b (coolant hole 105) does not have a thinning passage 105j and a thinning outlet 105n. Furthermore, the introduction passage 105h of the head passage 105b has an enlarged diameter section 105p located at the front end of the introduction passage 105h, with an inner diameter larger than that of the rear end of the introduction passage 105h. The rear end portion of the enlarged diameter section 105p has an inner diameter that increases (expands) as it moves toward the front end in the axial direction. The front end portion of the enlarged diameter section 105p has an inner diameter that decreases (contracts) as it moves toward the front end in the axial direction.

[0162] The tip surface channel 105i of the head channel 105b has a first channel 105q connected to the introduction channel 105h, a second channel 105r opening to the tip surface 3, and a third channel 105s connecting the first channel 105q and the second channel 105r. In this fifth modified example, a portion of the tip surface channel 105i may be connected to the margin channel 105t. The tip surface channel 105i may also branch off from the margin channel 105t.

[0163] As shown in Figures 22 and 23, the first channel 105q is connected to the enlarged diameter portion 105p of the introduction channel 105h. Specifically, the first channel 105q is connected to the tip portion of the enlarged diameter portion 105p. The first channel 105q extends radially outward from the connection point with the enlarged diameter portion 105p. Specifically, as the first channel 105q extends radially outward, it extends in the direction of drill rotation T.

[0164] The first channel 105q has a cross-sectional shape that is slit-shaped, a polygonal shape such as a flattened rectangle, an oval shape, or an ellipse shape. The radial dimension of the first channel 105q is larger than the circumferential dimension of the first channel 105q. Furthermore, the axial dimension of the first channel 105q decreases as it extends radially outward. That is, the cross-sectional area of ​​the first channel 105q decreases as it extends radially outward. Multiple first channels 105q are provided at intervals from each other in the circumferential direction. In the illustrated example, a pair of first channels 105q are provided at equal pitches in the circumferential direction.

[0165] As shown in Figures 19 to 21, the second channel 105r is groove-shaped and opens into the drill tip surface 3. In this fifth modified example, the second channel 105r is the tip surface nozzle 105m. Multiple tip surface nozzles 105m (second channel 105r) are provided spaced apart from each other in the circumferential direction. In the illustrated example, a pair of tip surface nozzles 105m are provided at equal pitches in the circumferential direction.

[0166] As shown in Figure 21, in a front view of the drill with the tip surface 3 viewed from the axial tip side, the tip surface nozzle 105m (second flow path 105r) extends substantially radially. That is, in this front view of the drill, the tip surface nozzle 105m extends in a direction intersecting the circumferential direction around the rotation axis O. More specifically, in a front view of the drill, the tip surface nozzle 105m extends towards the drill rotation direction T as it moves radially outward. Also, as shown in Figure 22, the tip surface nozzle 105m extends towards the axial rear end as it moves radially outward.

[0167] As shown in Figures 19 to 21, the tip surface nozzle 105m (second flow path 105r) opens in the region of the tip surface 3 located between the screw insertion hole 14 and the cutting edge 7 around the rotation axis O. In this fifth modification, the tip surface nozzle 105m opens only on the second relief surface 62 of the tip surface 3. That is, the entire opening area of ​​the tip surface nozzle 105m is located on the second relief surface 62. The tip surface nozzle 105m is located at the end of the second relief surface 62 in the drill rotation direction T.

[0168] In this fifth modification, the radial end of the tip surface nozzle 105m reaches either the radial outer edge (the ridge portion where the tip surface 3 and the outer peripheral surface 8 are connected) or the radial inner edge (the boundary portion between the tip surface 3 and the thinning surface 11, near the axis of rotation O) of the tip surface 3. In the illustrated example, the radial inner end of the tip surface nozzle 105m reaches the radial inner edge of the tip surface 3. Also, the radial outer end of the tip surface nozzle 105m reaches the radial outer edge of the tip surface 3. That is, the radial inner end of the tip surface nozzle 105m opens to the thinning surface 11, and the radial outer end of the tip surface nozzle 105m opens to the outer peripheral surface 8.

[0169] As shown in Figures 21 and 22, the third channel 105s connects the axial end of the first channel 105q to the groove bottom of the second channel 105r. Multiple third channels 105s are provided spaced apart from each other along the direction in which the second channel 105r extends. In the illustrated example, five third channels 105s are arranged side by side between a pair of first channels 105q and second channels 105r. Each third channel 105s is circular in shape. The central axis of the hole of each third channel 105s (not shown) extends radially outward as it approaches the axial end. That is, the central axis of the hole of each third channel 105s extends at an inclination with respect to the axis of rotation O.

[0170] The drill head 10E of the fifth modified example described above and the replaceable-tip drill 100 equipped therewith also provide the same excellent effects as those of the previously described embodiments and each of the modified examples.

[0171] In this fifth modification, the radial end of the nozzle 105m on the tip surface reaches the radial outer edge or radial inner edge of the tip surface 3.

[0172] In this case, the coolant ejected from the tip surface nozzle 105m can be used to cool the drill tip surface 3, as well as to cool other parts of the drill other than the drill tip surface 3. Specifically, if the radially outer end of the tip surface nozzle 105m reaches the radially outer edge of the drill tip surface 3, the coolant ejected from the tip surface nozzle 105m can be used to cool the margin 81 of the drill outer peripheral surface 8 and the inner peripheral surface of the machined hole in the workpiece. Also, if the radially inner end of the tip surface nozzle 105m reaches the radially inner edge of the drill tip surface 3, the coolant ejected from the tip surface nozzle 105m can be used to cool the thinning rake face 51 and the thinning blade 71.

[0173] Furthermore, the head flow path 105b may have a thinning nozzle 105n instead of a tip surface nozzle 105m.

[0174] Furthermore, although not specifically shown in the figures, the coolant hole 105 may have a coolant storage chamber located inside the holder 20 and connected to the holder flow path 105a. In this case, the coolant storage chamber is a hollow chamber formed inside the holder 20, which stores the coolant. Specifically, the coolant storage chamber can be, for example, a cylindrical chamber that is located inside the shank portion 101 and extends in the axial direction. By providing such a coolant storage chamber, the amount of coolant ejected can be stably increased, and the effects described above according to the present invention can be achieved more stably.

[0175] In the embodiments and modifications described above, the replaceable tip drill 100 is given as an example of a two-flute twist drill, but it is not limited to this. The replaceable tip drill may be a one-flute or a drill with three or more flutes. Accordingly, the number of screw insertion holes 14, clamp screws 30, and each coolant outlet may be changed as appropriate. However, the number of these is not limited to the same number as the number of cutting edges 7 of the drill.

[0176] Furthermore, the present invention is not limited to application to the above-described replaceable-tip drill 100, but may also be applied to a solid drill in which the effective drilling portion and the shank portion are integrally formed. However, when the present invention is applied to an indexable drill with a large drill bit diameter, where the peripheral speed of the margin located at the outermost circumference of the drill tends to be high, the effect of suppressing damage to the margin becomes particularly remarkable.

[0177] The present invention may be combined in any way that does not depart from the spirit of the invention, as described in the above embodiments and modifications, and the configurations may be added, omitted, substituted, or otherwise modified. Furthermore, the present invention is not limited by the above embodiments, but is limited only by the claims. [Industrial applicability]

[0178] The drill of the present invention allows for a stable supply of coolant near the margin, thereby suppressing margin damage. This extends tool life, reduces tool costs, and contributes to a lower environmental impact. Therefore, it has industrial applicability. [Explanation of Symbols]

[0179] 3…Tip surface 7…Cutting edge 8...Outer surface 10, 10A, 10B, 10C, 10D, 10E… Drill heads 20... Holder 30... Clamp screws 81... Margin 81a...First margin section 81b...Second margin section 82...Second bevel (outer clearance area) 100... Replaceable tip drill (drill) 104...Chip discharge groove 105... Coolant hole 105m…Tip surface spout 105u... Margin nozzle 105V...Connecting channel 106... Drill head mounting base O... Rotation axis T...Drill rotation direction

Claims

1. A drill centered on the axis of rotation, A chip evacuation groove extending from the tip surface of the drill toward the rear end in the axial direction, A cutting edge is positioned on the ridge of the chip discharge groove where the surface facing the direction of drill rotation around the rotation axis and the tip surface are connected, A margin is provided on the outer circumferential surface of the drill and connected to the surface of the chip evacuation groove facing the direction of drill rotation, The drill comprises a coolant hole extending inside the drill, The coolant hole has a margin outlet that opens into the margin. drill.

2. The margin is The first margin portion of the margin nozzle is arranged adjacent to the first margin portion in the direction of drill rotation, The margin nozzle has a second margin portion that is positioned adjacent to it on the opposite side of the drill rotation direction, The drill according to claim 1.

3. The margin nozzle is positioned away from the axial rear end portion of the ridge where the tip surface and the margin are connected. The drill according to claim 1 or 2.

4. The margin nozzle extends radially outward in the direction of the drill rotation. The drill according to claim 1 or 2.

5. The outer circumferential surface of the drill is provided with a secondary fretboard adjacent to the margin in the direction opposite to the drill rotation and located radially inward from the margin, The coolant hole is groove-shaped, recessed radially inward from the margin, and has a communication channel that connects the margin outlet with the tip surface, the second bevel surface, or the chip discharge groove. The drill according to claim 1 or 2.

6. The outer circumferential surface of the drill is provided with a secondary fretboard adjacent to the margin in the direction opposite to the drill rotation and located radially inward from the margin, The coolant hole has a second bevel outlet that opens into the second bevel surface. The drill according to claim 1 or 2.

7. The aforementioned second beveling surface nozzle extends radially outward in the direction of the drill rotation. The drill according to claim 6.

8. The coolant hole has a tip surface nozzle that opens to the tip surface, The drill according to claim 1 or 2.

9. In a cross-sectional view perpendicular to the axis of rotation, the connection between the margin nozzle and the margin forms an obtuse angle. The drill according to claim 1 or 2.

10. A holder extending axially along the aforementioned rotation axis, A drill head is detachably attached to a drill head mounting seat located at the axial end of the holder, The system includes a clamp screw for securing the drill head to the drill head mounting base. The drill according to claim 1 or 2.

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