Replaceable tip drill and drill head

Abstract

The present invention provides an interchangeable-tip drill and drill head that can stably supply coolant to the tip surface of the drill head, thereby improving cooling efficiency. [Solution] The device comprises a holder 20, a drill head 10, a clamp screw 30, a coolant hole 105, and a chip discharge groove 104. The drill head 10 has a cutting edge 7 positioned on the ridge where the surface of the chip discharge groove 104 facing the drill rotation direction T connects to the tip surface 3, and a screw insertion hole 14 that penetrates the drill head 10 axially. The clamp screw 30 is inserted through the screw insertion hole 14 and screwed into the female screw hole of the drill head mounting seat 106. The coolant hole 105 has a holder flow path extending inside the holder 20 and a head flow path 105b extending inside the drill head 10 and communicating with the holder flow path. The head flow path 105b has a tip surface outlet 105m that 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.

Description

Technical Field

[0001] The present invention relates to an insertable drill and a drill head.

Background Art

[0002] As a conventional insertable drill, there is known a configuration including a steel holder, a carbide drill head detachably attached to the tip of the holder, a clamp screw for fixing the drill head to the holder, and coolant holes extending inside the holder and inside the drill head (for example, Patent Document 1). In recent years, this type of insertable drill has attracted attention from the viewpoints of reducing tool costs by tungsten reduction and reducing environmental impact.

[0003] In an insertable drill, a plurality (for example, two) of clamp screws for fixing the drill head to the holder are provided, whereby the drill head can be firmly fastened to the holder. However, since a plurality of screw insertion holes for inserting the clamp screws are opened on the tip surface of the drill head, it is difficult to secure a space for opening the coolant hole on the tip surface of the drill head. If the coolant cannot be stably supplied to the tip surface of the drill head, there is a risk that the cutting heat generated during drilling cannot be efficiently removed (reduced).

[0004] Therefore, in Patent Document 1, oil holes that branch into two inside the cutting head are provided at the tool center of the tool body (holder) and the cutting head (drill head), and the branch part of the oil hole communicates with the bolt hole (screw insertion hole), and the outlet of the oil hole is formed by the inlet part of the bolt hole. According to Patent Document 1, the coolant can be supplied from the oil hole through the inlet part of the bolt hole to the tip surface of the cutting head.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] In recent years, there has been an increasing trend in the use of stainless steel and heat-resistant steel as workpiece materials. When drilling stainless steel and heat-resistant steel, cutting heat tends to increase more easily. Therefore, there is a need to stably supply coolant to the tip surface of the drill head to improve cooling efficiency. In this specification, stainless steel and heat-resistant steel may be replaced with stainless steel alloys and heat-resistant alloys.

[0007] The present invention aims to provide an interchangeable tip drill and drill head that can stably supply coolant to the tip surface of the drill head and improve cooling efficiency. [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] The drill head comprises a holder extending axially along the axis of rotation, a drill head detachably attached to a drill head mounting seat located at the axial end of the holder, a clamp screw for fixing the drill head to the drill head mounting seat, coolant holes extending inside the holder and inside the drill head, and a chip evacuation groove extending from the front surface of the drill head toward the rear end in the axial direction, wherein the drill head has a ridge portion where the surface of the chip evacuation groove facing the drill rotation direction around the axis of rotation and the front surface are connected. A replaceable tip drill having a cutting edge positioned thereon and a screw insertion hole that penetrates the drill head axially, wherein the clamp screw is inserted through the screw insertion hole and screwed into a female screw hole of the drill head mounting seat, and the coolant hole has a holder flow path extending inside the holder and a head flow path extending inside the drill head and communicating with the holder flow path, wherein the head flow path has a tip surface nozzle that opens in a region of the tip surface located between the screw insertion hole and the cutting edge around the rotation axis.

[0010] In the replaceable-tip drill of the present invention, the head flow path extending inside the drill head has a tip surface nozzle that opens in the region of the drill tip surface between the screw insertion hole and the cutting edge around the rotation axis. Coolant supplied from the holder flow path to the head flow path is ejected to the tip surface of the drill head through the tip surface nozzle.

[0011] By supplying coolant to the aforementioned area of ​​the drill tip, it is prevented from immediately flowing out into the chip evacuation groove adjacent to the screw insertion hole in the direction opposite to the drill rotation. As a result, the coolant tends to remain near the drill tip. In addition, the coolant is ejected from the tip surface nozzle to the part of the drill head tip surface closest to the cutting edge. Therefore, the cutting heat near the cutting area is efficiently removed (reduced) by the coolant, and the cooling efficiency is improved.

[0012] Furthermore, the present invention offers a high degree of freedom in designing the opening shape and area of ​​the nozzle on the tip surface. For example, in the case of a configuration where 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 described in Patent Document 1 (Japanese Patent No. 4703940), the opening shape of this nozzle is circular, and the opening area is based on the diameter of the screw head of the clamp screw, thus offering little design freedom.

[0013] On the other hand, in the present invention, the opening shape of the tip surface nozzle can be freely set in the region between the screw insertion hole and the cutting edge, for example, as a slit, oval, elliptical, polygonal, or groove shape. Furthermore, there is a high degree of freedom in the opening area and layout of the tip surface nozzle. According to the present invention, it is possible to increase the amount of coolant supplied to the tip surface of the drill and to secure a wider range of coolant supply.

[0014] Therefore, the present invention makes it possible to more effectively enhance the cooling and lubricating effects of the coolant depending on the application of the drill and cutting conditions. For example, even when drilling workpieces of materials that tend to generate a lot of heat during drilling, such as stainless steel and heat-resistant steel, it is possible to efficiently remove the heat and improve the cooling efficiency.

[0015] As described above, the present invention makes it possible to stably supply coolant to the tip surface of the drill head and improve cooling efficiency. This extends tool life, reduces tool costs, and contributes to reducing environmental impact.

[0016] [Aspect 2 of the present invention] The replaceable tip drill according to Embodiment 1, wherein, in a front view of the drill with the tip surface viewed from the tip side in the axial direction, the tip surface nozzle extends in a direction intersecting the circumferential direction around the rotation axis.

[0017] In this case, the tip surface nozzle 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 can be positioned to avoid the vicinity of the screw insertion hole through which the clamp screw is inserted and the cutting edge, while ensuring a large opening area of ​​the tip surface nozzle. This makes it possible to stably increase the amount of coolant supplied to the tip surface of the drill.

[0018] Furthermore, the coolant ejected from the nozzle on the tip surface is supplied to the drill tip surface 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, efficiently removing cutting heat and improving cooling efficiency.

[0019] [Aspect 3 of the present invention] The replaceable tip drill according to embodiment 2, wherein the radial end of the tip surface nozzle reaches the radial outer edge or radial inner edge of the tip surface.

[0020] In this case, the coolant ejected from the tip surface nozzle can be used to cool the drill tip surface, as well as to cool other parts of the drill. Specifically, if the radially outer end of the tip surface nozzle reaches the radially outer edge of the drill tip surface, the coolant ejected from the tip surface nozzle can be used to cool the margin of the drill's outer surface and the inner surface of the machined hole in the workpiece. Furthermore, if the radially inner end of the tip surface nozzle reaches the radially inner edge of the drill tip surface, the coolant ejected from the tip surface nozzle can be used to cool the thinning rake face and the thinning edge.

[0021] [Aspect 4 of the present invention] The tip surface has a relief surface connected to the cutting edge. The relief surface includes a first relief surface connected to the cutting edge and extending toward the rear end side in the axial direction as it goes from the cutting edge toward the reverse drill rotation direction around the rotation axis, and a second relief surface disposed adjacent to the first relief surface in the reverse drill rotation direction and extending toward the rear end side in the axial direction as it goes toward the reverse drill rotation direction. The tip surface coolant outlet is such that more than half of the opening area of the tip surface coolant outlet is disposed on the second relief surface. The replaceable tip drill according to any one of Aspects 1 to 3.

[0022] In this case, more than half of the opening area of the tip surface coolant outlet is disposed on the second relief surface that is away from the cutting edge. For this reason, while obtaining the above-described excellent effects by the tip surface coolant outlet, the tip strength of the cutting edge can be ensured.

[0023] 〔Aspect 5 of the present invention〕 The chip discharge groove has a thinning surface disposed at the axial tip of the chip discharge groove and connected to the tip surface. The head flow path has a thinning jet outlet that opens to the thinning surface. The replaceable tip drill according to any one of Aspects 1 to 4.

[0024] In this case, the head flow path has a thinning jet outlet that opens to the thinning surface. The coolant ejected from the thinning jet outlet is supplied to the thinning blade disposed at the radially inner end of the cutting edge, the thinning rake surface adjacent to the thinning blade, and the drill tip surface. Among the cutting edges, the thinning blade and the thinning rake surface, etc., where the cutting resistance tends to be large, can be efficiently cooled by the coolant ejected from the thinning jet outlet. Thereby, the loss of the thinning blade and the crater wear of the thinning rake surface can be suppressed. Also, it becomes possible to ensure a larger amount of coolant supply to the drill tip surface, and the effects of the present invention described above become more remarkably prominent.

[0025] 〔Aspect 6 of the present invention〕 The drill head mounting seat has a mounting surface facing the tip side in the axial direction and a fitting hole recessed from the mounting surface toward the rear end side in the axial direction. The drill head faces the rear end side in the axial direction and has a seating surface that contacts the mounting surface and a fitting portion that protrudes from the seating surface toward the rear end side in the axial direction and fits into the fitting hole. The holder flow path has a holder-side connection port that opens inside the fitting hole, and the head flow path is disposed inside the fitting portion and has a head-side connection port that is connected to the holder-side connection port. The cutting-edge replaceable drill according to any one of Aspects 1 to 5.

[0026] In the above configuration, the fitting structure between the fitting hole of the drill head mounting seat and the fitting portion of the drill head is utilized to connect the holder-side connection port of the holder flow path and the head-side connection port of the head flow path. Therefore, it is easy to arrange the coolant hole without interfering with the screw insertion hole through which the clamp screw is inserted or the female screw hole to which the clamp screw is screwed, and the degree of freedom in drill design is increased.

[0027] 〔Aspect 7 of the present invention〕 A plurality of chip discharge grooves are provided at intervals in the circumferential direction, the holder flow path has a plurality of branch flow paths arranged at intervals in the circumferential direction, each of the branch flow paths is located between the adjacent chip discharge grooves in the circumferential direction, and the plurality of branch flow paths merge with each other at the connection portion with the head flow path. The cutting-edge replaceable drill according to any one of Aspects 1 to 6.

[0028] In this case, a plurality of branch flow paths ensure a sufficient coolant flow rate flowing in the holder, and at the connection portion between the holder flow path and the head flow path, these branch flow paths are merged. Thereby, it becomes easy to suppress the interference between the screw insertion hole through which the clamp screw is inserted or the female screw hole to which the clamp screw is screwed, and the coolant hole.

[0029] 〔Aspect 8 of the present invention〕 The holder channel has a plurality of linear channels that extend inclined with respect to the rotation axis, the plurality of linear channels are arranged in the axial direction and connected to one another, and one of the plurality of linear channels located at the tip is connected to the head channel, as described in any one of embodiments 1 to 7.

[0030] In this case, the holder channel is formed by connecting multiple straight channels that are inclined with respect to the axis of rotation. This simplifies the structure of the holder channel and facilitates the manufacture of the holder.

[0031] [Aspect 9 of the present invention] The replaceable tip drill according to any one of embodiments 1 to 8, wherein the coolant hole has a coolant storage chamber located inside the holder and connected to the holder flow path.

[0032] In this case, the coolant storage chamber is a hollow chamber formed inside the holder, which stores the coolant. 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 are more stably achieved.

[0033] [Aspect 10 of the present invention] A drill head that is detachably attached to a drill head mounting seat of a holder and rotated together with the holder around a rotation axis, the drill head having: a chip evacuation groove extending from the tip surface of the drill head toward the rear end in the axial direction; a cutting edge positioned on the ridge of the chip evacuation groove where the surface facing the drill rotation direction around the rotation axis connects with the tip surface; a screw insertion hole that penetrates the drill head axially and through which a clamp screw is inserted; and a head flow path that extends inside the drill head and communicates with a holder flow path that extends inside the holder, wherein the head flow path has a tip surface nozzle that opens in a region of the tip surface located between the screw insertion hole and the cutting edge around the rotation axis.

[0034] According to the drill head of the present invention, the same excellent effects as those of the replaceable-tip drill of the present invention described above can be obtained. [Effects of the Invention]

[0035] According to the above-described aspect of the present invention, an interchangeable tip drill and drill head are provided that can stably supply coolant to the tip surface of the drill head and improve cooling efficiency. [Brief explanation of the drawing]

[0036] [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 (longitudinal section) of the drill head, specifically showing the section VIII-VIII in Figure 2. [Figure 9] Figure 9 is a cross-sectional view (longitudinal section) of the drill head, specifically showing the section IX-IX in Figure 2. [Figure 10] Figure 10 is a cross-sectional view of the drill head, specifically showing the XX cross-section in Figure 3. [Figure 11] Figure 11 is a perspective view showing the drill head of the first modified example. [Figure 12] Figure 12 is a perspective view showing the drill head of the first modified example. [Figure 13] Figure 13 is a front view showing the drill head of the first modified example. [Figure 14] Figure 14 is a cross-sectional view (longitudinal section) showing the XIV-XIV section of Figure 13. [Figure 15] Figure 15 is a cross-sectional view (cross-sectional plan view) of the drill head of the first modified example, specifically showing the XV-XV section of Figure 14. [Figure 16] Figure 16 is a perspective view showing the drill head of the second modified example. [Figure 17] Figure 17 is a perspective view showing the drill head of the second modified example. [Figure 18] Figure 18 is a cross-sectional view of the drill head of the second modified example. [Figure 19] Figure 19 is a side view showing the drill head of the third modified example. [Figure 20] Figure 20 is a cross-sectional view showing a portion of the drill head of the fourth modified example. [Figure 21] Figure 21 is a cross-sectional view (horizontal view) showing a part of the drill head of the fifth modified example. [Modes for carrying out the invention]

[0037] 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 10. 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.

[0038] 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.

[0039] 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.

[0040] [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.

[0041] 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.

[0042] [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).

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] As shown in Figure 5, the coolant hole 105 extends through the interior of the drill. Specifically, the coolant hole 105 extends through the interior of the holder 20 and the interior of the drill head 10. Although not shown in particular, the coolant hole 105 is provided through 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] [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).

[0055] 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.

[0056] 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.

[0057] 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 axially towards the rear end as it is directed away from the drill rotation direction.

[0058] 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.

[0059] 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.

[0060] 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).

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] As shown in Figures 7 and 8, 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 extending 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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).

[0082] 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.

[0083] 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.

[0084] [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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] [Coolant holes] Here, the coolant hole 105 of this embodiment will be described in detail. 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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).

[0095] 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.

[0096] 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.

[0097] 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.

[0098] As shown in Figures 6 to 10, the head channel 105b is provided to penetrate the drill head 10 in the axial direction. The axial tip end of the head channel 105b 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.

[0099] The head channel 105b has an introduction channel 105h connected to the holder channel 105a for introducing coolant from the holder channel 105a into the head channel 105b, an end-face channel 105i connected to the introduction channel 105h and opening to the end-face 3, and a thinning channel 105j connected to the introduction channel 105h and opening to the thinning surface 11.

[0100] 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. 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.

[0101] As shown in Figure 8, 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 10, 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 spaced apart from each other in the circumferential direction. In this embodiment, a pair of tip surface channels 105i are provided at equal pitches in the circumferential direction.

[0102] The tip surface channel 105i 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 radial dimension of the tip surface channel 105i is larger than the circumferential dimension of the tip surface channel 105i.

[0103] As shown in Figures 2, 6, and 8, the axial tip of the tip surface flow channel 105i is a tip surface nozzle 105m that opens onto the drill tip surface 3. That is, the head flow channel 105b has a tip surface nozzle 105m. Multiple tip surface nozzles 105m are provided at intervals from each other in the circumferential direction. In this embodiment, a pair of tip surface nozzles 105m are provided at equal pitches in the circumferential direction.

[0104] 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.

[0105] More specifically, the nozzle 105m of this embodiment opens across the first relief surface 61 and the second relief surface 62 of the nozzle surface 3. Furthermore, more than half of the opening area of ​​the nozzle 105m is located on the second relief surface 62.

[0106] As shown in Figure 2, 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 this embodiment, 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.

[0107] 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.

[0108] In this embodiment, 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 portion between the tip surface 3 and the thinning surface 11, near the axis of rotation O). Furthermore, 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).

[0109] As shown in Figure 9, 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 10, the thinning channel 105j extends radially outward from the connection point with the introduction channel 105h toward the direction of anti-drill rotation. Multiple thinning channels 105j are provided spaced apart from each other in the circumferential direction. In this embodiment, 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.

[0110] 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 tip surface channel 105i. The circumferential dimension of the thinning channel 105j is smaller than the circumferential dimension of the tip surface channel 105i.

[0111] As shown in Figures 2, 6, and 9, the axial tip of the thinning channel 105j is a thinning nozzle 105n that opens onto the thinning surface 11. That is, the head channel 105b has a thinning nozzle 105n. Multiple thinning nozzles 105n are provided spaced apart from each other in the circumferential direction. In this embodiment, a pair of thinning nozzles 105n are provided at equal pitches in the circumferential direction. The tip surface nozzles 105m and thinning nozzles 105n are arranged alternately in the circumferential direction.

[0112] 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.

[0113] As shown in Figure 2, 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 this embodiment, 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.

[0114] 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.

[0115] The opening shape of the thinning nozzle 105n is not limited to the configuration of this embodiment. Although not specifically shown, the thinning nozzle 105n may be circular, a regular polygon, or the like when viewed from the front of the drill.

[0116] [Effects of this embodiment] In the replaceable tip drill 100 and drill head 10 of this embodiment described above, the head flow path 105b extending inside the drill head 10 has a tip surface outlet 105m that 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. Coolant supplied from the holder flow path 105a to the head flow path 105b is ejected onto the tip surface 3 of the drill head 10 through the tip surface outlet 105m.

[0117] 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 (reduced) by the coolant, and the cooling efficiency is improved.

[0118] Furthermore, in this embodiment, 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 the above-mentioned Patent Document 1 (Japanese Patent Publication 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 the degree of freedom in design is low.

[0119] On the other hand, in this embodiment, 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 this embodiment, the amount of coolant supplied to the drill tip surface 3 can be increased, and a wider range of coolant supply can be secured.

[0120] Therefore, in this embodiment, the cooling and lubricating effects of the coolant can be more effectively enhanced depending on the application of the drill and cutting conditions. For example, even when drilling workpieces of materials that tend to generate a lot of heat during drilling, such as stainless steel and heat-resistant steel, the heat can be efficiently removed and the cooling efficiency can be improved.

[0121] As described above, according to this embodiment, coolant can be stably supplied to the tip surface 3 of the drill head 10, thereby improving cooling efficiency. This extends tool life, reduces tool costs, and contributes to reducing environmental impact.

[0122] In this embodiment, when viewing the tip surface 3 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.

[0123] 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.

[0124] 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.

[0125] In this embodiment, more than half of the opening area of ​​the tip surface nozzle 105m is located on the second relief surface 62.

[0126] 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.

[0127] In this embodiment, the head flow path 105b has a thinning nozzle 105n that opens to 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 effects of this embodiment described above even more pronounced.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] [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.

[0135] Figures 11 to 15 show 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 Figures 11 to 15, the first modification drill head 10A differs from the drill head 10 of the above-described embodiment in the configuration of the head flow path 105b of the coolant hole 105.

[0136] Specifically, in this first modified example, the head channel 105b does not have a thinning channel 105j and a thinning nozzle 105n. Furthermore, the introduction channel 105h of the head channel 105b has an enlarged diameter section 105p located at the front end of the introduction channel 105h, with an inner diameter larger than that of the rear end of the introduction channel 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.

[0137] 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.

[0138] As shown in Figures 14 and 15, 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.

[0139] 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.

[0140] As shown in Figures 11 to 13, the second channel 105r is groove-shaped and opens into the drill tip surface 3. In this first 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.

[0141] As shown in Figure 13, 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 in the radial direction. 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 14, the tip surface nozzle 105m extends towards the axial rear end as it moves radially outward.

[0142] As shown in Figures 11 to 13, 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 first modified example, the tip surface nozzle 105m opens only on the second flank surface 62 of the tip surface 3. That is, the entire opening area of ​​the tip surface nozzle 105m is located on the second flank surface 62. The tip surface nozzle 105m is located at the end of the second flank surface 62 in the drill rotation direction T.

[0143] In this first 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.

[0144] As shown in Figures 13 and 14, 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.

[0145] The first modified drill head 10A and the replaceable-tip drill 100 equipped therewith, as described above, also provide the same excellent effects as those of the previously described embodiment.

[0146] In this first modification, the radial end of the nozzle 105m reaches the radial outer edge or radial inner edge of the nozzle 3.

[0147] 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.

[0148] Figures 16 to 18 show a second modified example of the drill head 10 described in the above embodiment, which is a drill head 10B. Although not specifically shown, the drill head 10B is detachably attached to the drill head mounting seat 106 of the holder 20. The drill head 10B constitutes the tip of the effective drilling portion 102 of the replaceable tip drill 100. As shown in Figures 16 to 18, the drill head 10B of the second modified example differs from the drill heads 10 and 10A described above in the configuration of the head flow path 105b and margin 81 of the coolant hole 105. Note that in Figures 16 to 18, the tip surface flow path 105i, tip surface nozzle 105m, thinning flow path 105j, and thinning nozzle 105n described above are not shown.

[0149] Specifically, in this second modification, the head channel 105b is connected to the introduction channel 105h and has a margin channel 105t that opens into the margin 81. The margin channel 105t extends radially outward from the connection point with the introduction channel 105h. As shown in Figure 18, 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 spaced apart from each other in the circumferential direction. In the illustrated example, a pair of margin channels 105t are provided at equal pitches in the circumferential direction.

[0150] As shown in Figures 16 and 17, the margin channel 105t has a cross-sectional shape such as a slit, 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. A portion of the margin channel 105t may be connected to a tip surface channel 105i or a thinning channel 105j, which are not shown.

[0151] As shown in Figures 16 to 18, the radial outer end of the margin channel 105t is a margin outlet 105u that opens into the margin 81. That is, the head channel 105b has a margin outlet 105u. Multiple margin outlets 105u are provided at intervals from each other in the circumferential direction. In the illustrated example, a pair of margin outlets 105u are provided at equal pitches in the circumferential direction.

[0152] 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 18, the margin nozzle 105u extends radially outward in the direction of drill rotation T.

[0153] Furthermore, as shown in Figures 16 to 18, 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.

[0154] In this second modified example, 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. In the illustrated example, the circumferential dimension (margin width) of the first margin portion 81a is larger than the circumferential dimension of the second margin portion 81b. The second margin portion 81b may be positioned radially inward of the first margin portion 81a by several tens of micrometers.

[0155] Furthermore, in this second modification, the head channel 105b is groove-shaped, recessing radially inward from the margin 81, and has a communication channel 105v that connects the margin nozzle 105u and the tip surface 3. The communication channel 105v is located adjacent to the margin nozzle 105u on the axial tip side of the margin nozzle 105u. The communication channel 105v extends in the direction of drill rotation T as it moves axially toward the tip side from the connection point with the margin nozzle 105u. In the illustrated example, the circumferential dimension (groove width dimension) of the communication channel 105v is the same as the circumferential dimension (opening width dimension) of the margin nozzle 105u. The axial tip of the communication channel 105v opens to the drill tip surface 3.

[0156] The drill head 10B of the second modified example described above and the replaceable-tip drill 100 equipped therewith also provide the same excellent effects as those of the previously described embodiment and the first modified example.

[0157] In this second modification, the head flow path 105b has a margin outlet 105u that opens into the margin 81.

[0158] In general, when drilling workpieces made of stainless steel or heat-resistant steel, the machining hole tends to shrink due to the rise in cutting heat, which increases the load on the margin that rubs against the inner surface of the machining hole. As a result, welding to the margin occurs prematurely, or the margin is damaged. In particular, with indexable insert drills where the drill bit diameter is large, the peripheral speed of the margin located at the outermost circumference of the drill also increases, and the load on the margin also increases, making the margin more susceptible to damage.

[0159] According to the second modification described above, since the head flow path 105b has a margin outlet 105u, the margin 81 and the inner circumferential surface of the machined hole in the workpiece (hereinafter sometimes referred to as the area around the margin 81) can be efficiently cooled by the coolant ejected from the margin outlet 105u. Since the amount of coolant supplied to the margin 81 can be increased, the cutting heat around the margin 81 can be effectively removed (reduced), and damage to the margin 81 can be suppressed.

[0160] Furthermore, the margin 81 has a first margin portion 81a positioned adjacent to the drill rotation direction T of the margin nozzle 105u, and a second margin portion 81b positioned adjacent to the margin nozzle 105u on the opposite side of the drill rotation direction T.

[0161] 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 the second modified example above, 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.

[0162] 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.

[0163] Furthermore, 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. As a result, the above-mentioned effects are obtained by the margin nozzle 105u while ensuring the strength of the shoulder.

[0164] Furthermore, since the margin outlet 105u extends radially outward and toward the drill rotation direction T, the coolant ejected from the margin outlet 105u is prevented from immediately flowing in the opposite direction of drill rotation and is more likely to remain near the margin 81. This further improves the cooling efficiency near the margin 81.

[0165] Furthermore, the head flow path 105b is groove-shaped, recessing radially inward from the margin 81, and has a communication flow path 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.

[0166] Figure 19 is a side view showing the third modified drill head 10C. Although not specifically shown, the drill head 10C is detachably attached to the drill head mounting seat 106 of the holder 20. The drill head 10C constitutes the tip of the effective drilling portion 102 of the replaceable tip drill 100. As shown in Figure 19, the drill head 10C of the third modified example differs from the drill head 10B described above in part in the configuration of the head flow path 105b. Note that in Figure 19, the tip surface flow path 105i, tip surface nozzle 105m, thinning flow path 105j, and thinning nozzle 105n described above are not shown.

[0167] Specifically, in this third modification, the head flow path 105b does not have a connecting flow path 105v. That is, when a margin outlet 105u is provided, a connecting flow path 105v does not need to be provided. According to the third modification described above, the structure of the drill head 10C is simplified, and the strength of the ridge (shoulder) where the drill tip surface 3 and the margin 81 are connected is further increased.

[0168] Figure 20 is a cross-sectional view (horizontal cross-section) showing a part of the drill head 10D of the fourth modified example. More specifically, Figure 20 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 10D.

[0169] In this fourth modified example, as shown in Figure 20, 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.

[0170] According to the fourth 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.

[0171] Figure 21 is a cross-sectional view (horizontal cross-section) showing a part of the drill head 10E of the fifth modified example. More specifically, Figure 21 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 10E.

[0172] As shown in Figure 21, in this fifth 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.

[0173] In the fifth modification 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.

[0174] 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.

[0175] Furthermore, although not specifically shown in the figures, the head channel 105b may be connected to the introduction channel 105h and have a secondary chamfering channel that opens to the secondary chamfering surface (outer peripheral clearance portion) 82. The radial outer end of the secondary chamfering channel is a secondary chamfering outlet (outer peripheral clearance portion outlet) that opens to the secondary chamfering surface 82. In other words, the head channel 105b may further have a secondary chamfering outlet.

[0176] In this case, since the head passage 105b 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 on the outer surface 8 of the drill as the drill rotates. As a result, the cooling efficiency near the margin 81 is further enhanced.

[0177] 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.

[0178] 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 are more stably achieved.

[0179] Furthermore, the head flow path 105b may have a thinning nozzle 105n instead of a tip surface nozzle 105m.

[0180] 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.

[0181] 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]

[0182] The indexable drill and drill head of the present invention enable a stable supply of coolant to the tip surface of the drill head, thereby improving cooling efficiency. This extends tool life, reduces tool costs, and contributes to reducing environmental impact. Therefore, it has industrial applicability. [Explanation of Symbols]

[0183] 3…Tip surface 6...Escape 7…Cutting edge 8...Outer surface 9…Seat surface 10, 10A, 10B, 10C, 10D, 10E… Drill heads 11...Thinning surface 13…Matching part 14…Screw insertion hole 20... Holder 30... Clamp screws 61...First escape route 62...Second escape route 81... Margin 82...Second bevel (outer clearance area) 100... Replaceable tip drill 104...Chip discharge groove 105... Coolant hole 105a...Holder flow path 105b... Head channel 105c... Branch channel 105d, 105e… straight channel 105f...Holder side connection port 105k... Head-side connection port 105m…Tip surface spout 105n... Thinning nozzle 105u... Margin nozzle 106... Drill head mounting base 107…Mounting surface 109…Matching hole 110...Female screw hole O... Rotation axis T...Drill rotation direction

Claims

1. A holder extending axially along the axis of rotation, A drill head is detachably attached to a drill head mounting seat located at the axial end of the holder, A clamp screw for fixing the drill head to the drill head mounting base, Coolant holes extending inside the holder and inside the drill head, The drill head comprises a chip evacuation groove extending from the tip surface toward the rear end in the axial direction, The aforementioned drill head is 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, The drill head has a screw insertion hole that penetrates it axially, The clamp screw is inserted through the screw insertion hole and screwed into the female screw hole of the drill head mounting seat. The coolant hole is A holder channel extending inside the holder, It has a head channel that extends inside the drill head and communicates with the holder channel, The head flow path has a tip surface nozzle that opens in a region of the tip surface located between the screw insertion hole and the cutting edge around the rotation axis. Replaceable tip drill.

2. In a front view of the drill, with the tip surface viewed from the axial tip side, the tip surface nozzle extends in a direction intersecting the circumferential direction around the rotation axis. The replaceable tip drill according to claim 1.

3. The radial end of the nozzle on the tip surface reaches the radial outer edge or radial inner edge of the tip surface. The replaceable tip drill according to claim 2.

4. The aforementioned tip surface has a relief surface that is connected to the cutting edge, The aforementioned relief surface is, A first relief surface is connected to the cutting edge and extends toward the rear end in the axial direction as it moves from the cutting edge toward the anti-drill rotation direction around the rotation axis, It has a second relief surface, which is positioned adjacent to the first relief surface in the direction opposite to the drill rotation, and which extends toward the rear end in the axial direction as it is directed toward the direction opposite to the drill rotation, The aforementioned tip surface nozzle has more than half of its opening area located on the second relief surface. The replaceable tip drill according to any one of claims 1 to 3.

5. The chip discharge groove has a thinning surface located at the axial end of the chip discharge groove and connected to the end surface, The head flow path has a thinning nozzle that opens to the thinning surface. The replaceable tip drill according to any one of claims 1 to 3.

6. The aforementioned drill head mounting base is A mounting surface facing the axial end, It has a fitting hole recessed in the axial direction toward the rear end from the mounting surface, The aforementioned drill head is A seating surface facing the rear end side in the axial direction and in contact with the mounting surface, It has a fitting portion that protrudes from the seating surface toward the rear end in the axial direction and fits into the fitting hole, The holder channel has a holder-side connection port that opens into the inside of the fitting hole, The head channel is located inside the fitting portion and has a head-side connection port connected to the holder-side connection port. The replaceable tip drill according to any one of claims 1 to 3.

7. Multiple chip discharge grooves are provided at intervals from each other in the circumferential direction. The holder channel has a plurality of branch channels arranged at intervals from each other in the circumferential direction. Each of the aforementioned branch channels is located between adjacent chip discharge grooves in the circumferential direction. The multiple branch channels merge with each other at the connection point with the head channel. The replaceable tip drill according to any one of claims 1 to 3.

8. The holder flow path has a plurality of straight flow paths that extend at an inclination with respect to the rotation axis, Multiple of the aforementioned linear channels are arranged in a line in the axial direction and are connected to one another. Of the multiple linear channels, one linear channel located at the very front is connected to the head channel. The replaceable tip drill according to any one of claims 1 to 3.

9. The coolant hole is located inside the holder and has a coolant storage chamber connected to the holder flow path. The replaceable tip drill according to any one of claims 1 to 3.

10. A drill head that is detachably attached to the drill head mounting seat of a holder and rotates together with the holder around a rotation axis, A chip evacuation groove extending from the tip surface of the drill head 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, The drill head has a screw insertion hole through which a clamp screw is inserted, The drill head has a head channel that extends inside the drill head and communicates with a holder channel that extends inside the holder, The head flow path has a tip surface nozzle that opens in a region of the tip surface located between the screw insertion hole and the cutting edge around the rotation axis. Drill head.

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