JP2012206216A - Drill holder and edge exchangeable drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress outflow of a coolant onto the holder proximal side, stay the coolant sufficiently at a distal part of a holder body, and enhance the abrasion resistance of a cutting edge, thereby performing cutting work stably.SOLUTION: This drill holder includes: an axial holder body 2; an insert attachment seat 4 for detachably attaching at least two cutting inserts 3 which are formed inwardly and outwardly radially at the distal part of the holder body 2, and have cutting edges 3a; a plurality of chips discharge slits 6 which are formed at intervals circumferentially on a peripheral face of the holder body 2, open to a distal face 5 of the holder body 2, also include the insert attachment seat 4, and extend toward the proximal side of the axial holder body 2; a land part 12 formed between the chips discharge slits 6 adjacent circumferentially of the peripheral face of the axial holder body 2; and a coolant supply hole 7 for supplying the distal part of the holder body 2 with the coolant. A recess part 13 is formed in the distal face 5 of the holder body 2.

Description

  The present invention relates to a drill holder and a blade-tip replaceable drill using the drill holder.

  Conventionally, as this type of drill holder, for example, as shown in Patent Document 1 below, a shaft body is formed, and a diameter of the holder body that is rotated around the axis line and a tip end portion of the holder body so as to sandwich the axis line. At least two inward and outward directions, and a plurality of insert mounting seats on which cutting inserts having cutting edges are detachably mounted, and a plurality of circumferentially spaced outer peripheral surfaces of the holder body In addition, there is known one provided with a chip discharge groove that opens to the front end surface of the holder main body and includes the insert mounting seat and extends toward the base end side of the holder main body. In addition, the site | part located between the chip discharge grooves adjacent to the circumferential direction among the outer peripheral surfaces of a holder main body is called the land part.

Generally, such a drill holder is formed so as to penetrate the inside of the holder main body, and a coolant supply hole for supplying a coolant to the tip end portion of the holder main body is formed. The coolant is supplied from the coolant supply hole to the vicinity of the cutting edge of the cutting insert, so that the cutting edge is cooled and the wear resistance is enhanced, so that the sharpness is maintained and the chips generated by the cutting are removed. It is conveyed toward the base end side of the holder body through the discharge groove.
Further, as solid type drills other than the blade tip type drills, for example, those described in Patent Documents 2 to 4 below are known.

Japanese Patent Publication No.53-15234 JP 51-33372 A Japanese Utility Model Publication No. 59-183713 Japanese Utility Model Publication No. 63-47814

However, the conventional drill holder and the blade tip type drill have the following problems.
In other words, in this type of cutting edge replaceable drill, the outer peripheral surface (land portion) of the holder body made of steel or the like does not contribute to processing (including burnishing other than cutting), and therefore the normal land portion is the insert mounting seat. It is made to retreat one step inward in the diameter direction rather than the edge in the diameter direction of the cutting insert attached to. In other words, a gap is formed between the inner peripheral surface of the processed hole drilled in the work material by drilling and the land portion (see FIG. 2 of Patent Document 1). Further, the cutting blade located on the tip side of the holder in the cutting insert protrudes from the tip surface of the holder body, and a gap is formed between the tip surface and the bottom surface of the machining hole. Usually, since the clearance angle is set on the front end surface of the holder main body, the gap between the front end surface and the bottom surface of the machining hole becomes large. Due to these gaps, the coolant supplied to the tip of the holder body cools the cutting edge, contributes to the wear resistance of the cutting edge, and conveys the chips without passing through the gap. It flowed out toward the base end side of this, and a sufficient coolant effect could not be obtained. In addition, in order to obtain a sufficient coolant effect, it was necessary to secure a large amount of coolant supply.

  On the other hand, when the land portion is formed to be flush with the radially outer edge of the cutting insert for the purpose of eliminating the gap between the land portion and the inner peripheral surface of the machining hole, Although the outflow of the coolant is suppressed, the holder main body and the machining hole are rubbed with each other, a large cutting resistance is generated, and the machining quality of the hole surface is impaired.

  The present invention has been made in view of such circumstances, and without increasing the cutting resistance, the coolant is prevented from flowing out to the holder base end side, and the coolant is applied to the tip end portion of the holder body. An object of the present invention is to provide a drill holder and a blade-tip-replaceable drill that can be sufficiently retained and that can stably perform cutting by increasing the wear resistance of the cutting edge.

In order to achieve the above object, the present invention proposes the following means.
That is, the present invention has an axial shape and is formed with at least two holder main bodies that are rotated around the axis, and at the distal end of the holder main body, at the radially inner and outer sides so as to sandwich the axis. A plurality of insert mounting seats on which cutting inserts having cutting edges are detachably mounted, and a plurality of circumferentially spaced outer peripheral surfaces of the holder main body, which are open at the front end surface of the holder main body and the insert mounting A chip discharge groove including a seat and extending toward the proximal end of the holder main body, a land portion formed between adjacent chip discharge grooves in the circumferential direction of the outer peripheral surface of the holder main body, and the holder A drill holder having a coolant supply hole that is formed so as to penetrate the inside of the main body and supplies coolant to the tip of the holder main body, and a recess is formed in the tip surface of the holder main body It is characterized in that is.
Moreover, the blade-tip-exchangeable drill of the present invention is characterized by including the above-described drill holder and the cutting insert.

According to the drill holder of the present invention and the blade-tip replaceable drill using the drill holder, since the concave portion is formed on the front end surface of the holder body (hereinafter sometimes referred to as the holder front end surface), the following effects are produced.
That is, a part of the coolant supplied from the coolant supply hole to the tip of the holder body passes through the gap between the holder tip surface and the land portion and the inner peripheral surface of the processing hole, and the base end of the holder body. At this time, the coolant stays in the recess formed on the front end surface of the holder. That is, the coolant that has flowed into the recess remains in the recess, so that the coolant is always supplied to the tip surface.

  In this way, since the coolant outflow to the holder base end side is suppressed, the coolant tends to stay at the tip of the holder main body, and therefore the coolant supply to the tip of the holder main body without increasing the coolant supply amount. A sufficient amount can be secured to improve the wear resistance of the cutting edge.

  In addition, the front end surface of the holder body is one step backward from the cutting edge located on the holder front end side of the cutting insert attached to the insert mounting seat, and the clearance angle is set on the front end surface, A gap is also formed between the holder tip surface and the bottom surface of the processing hole. According to the present invention, the above-described retention action of the recesses makes it easier for coolant to be supplied from the gap toward the cutting insert, and the coolant flows out to the land portion and the chip discharge groove without cooling or lubricating the cutting edge. Such a thing is suppressed.

Therefore, according to the present invention, the tool life of the cutting insert can be extended, and stable cutting can be performed.
Further, according to this configuration, for example, the land portion does not need to be brought into contact with the inner peripheral surface of the machining hole for the purpose of suppressing the outflow of the coolant to the holder base end side, so that the cutting resistance does not increase. .

  Moreover, the drill holder of this invention WHEREIN: The said recessed part is good also as forming the space | interval in the intersection ridgeline of the front end surface of the said holder main body, and the said land part.

  In this case, since the concave portion is formed on the front end surface of the holder main body with an interval between the intersecting ridge lines between the front end surface and the land portion, the coolant temporarily stored in the concave portion is more likely to be on the land portion. It is difficult to get on. Specifically, for example, unlike the present invention, when the concave portion is formed to open on the intersecting ridge line, the coolant temporarily stored in the concave portion passes through the concave portion from the holder front end surface on the land portion. It is easy to be guided to the land, and it may be easy to get on the land portion. On the other hand, according to the present invention, since the concave portion is not on the intersecting ridge line, that is, does not open to the land portion, it is possible to reliably suppress the coolant from running from the holder front end surface onto the land portion.

  Further, since the recesses are formed with a space between the intersecting ridge lines, the coolant whose flow velocity has decreased due to the staying action of the recesses is positioned rearward in the tool rotation direction instead of being difficult to go radially outward. It becomes easy to be supplied to the cutting insert of the insert mounting seat. Therefore, the effects described above can be obtained remarkably.

  In the drill holder according to the present invention, a plurality of the recesses may be formed.

  In this case, the above-mentioned staying action by the recess is obtained at a plurality of locations on the front end surface of the holder body, the pressure loss is sufficiently increased, and the outflow of the coolant from the front end surface is effectively suppressed.

  Further, in the drill holder of the present invention, a plurality of fan-shaped portions are formed on the distal end surface of the holder main body so as to be spaced apart from each other in the circumferential direction, and the concave portions are formed corresponding to the fan-shaped portions. It is good as well.

  In this case, a chip discharge groove is disposed between the adjacent fan-shaped portions so as to be spaced apart in the circumferential direction on the holder front end surface, and an insert mounting seat is formed in the chip discharge groove. That is, an insert mounting seat is arranged behind the fan-shaped portion in the tool rotation direction, and a cutting insert is mounted on the insert mounting seat. According to the present invention, since the concave portion is formed corresponding to the fan-shaped portion, the coolant temporarily stored in the concave portion is easily supplied to the cutting insert located at the rear in the tool rotation direction.

  According to the drill holder and the blade-tip replaceable drill of the present invention, the coolant is prevented from flowing out to the holder proximal end side without increasing the cutting resistance, and the coolant is sufficiently retained at the distal end portion of the holder main body. Therefore, stable cutting can be achieved by increasing the wear resistance of the cutting edge.

It is a perspective view which shows the blade-tip-exchange-type drill which concerns on one Embodiment of this invention. It is a front view which shows the blade-tip-exchange-type drill which concerns on one Embodiment of this invention. It is a figure which shows the AA cross section in the front-end | tip part of the holder main body of FIG. It is a figure which shows the BB cross section in the front-end | tip part of the holder main body of FIG. It is a figure which expands and shows the front-end | tip part of the holder main body in FIG. It is the perspective view which looked at the front-end | tip part of the blade-tip-exchange-type drill which concerns on one Embodiment of this invention from the substantially side. It is a figure which expands and shows the fan-shaped part of the holder front end surface in FIG. It is a figure which expands and shows the fan-shaped part of the holder front end surface in FIG.

Hereinafter, the drill holder 1 which concerns on one Embodiment of this invention, and the blade-tip-exchange-type drill 10 using the same are demonstrated with reference to FIGS.
The drill holder 1 and the blade-tip replaceable drill 10 according to the present embodiment drill holes in a work material made of steel or the like by drilling.

As shown in FIGS. 1 and 2, the drill holder 1 has an axial shape, a holder body 2 that is rotated around the axis O, and a radial direction so that the axis O is sandwiched between the distal ends of the holder body 2. At least two are formed on the inner side and the outer side, and a plurality of insert mounting seats 4 on which cutting inserts 3 having cutting edges are detachably mounted, and a plurality of outer peripheral surfaces of the holder body 2 are formed at intervals in the circumferential direction. Among the outer peripheral surface of the holder main body 2 and the chip discharge groove 6 that opens to the front end surface 5 of the holder main body 2 and includes the insert mounting seat 4 and extends toward the proximal end side of the holder main body 2, A land portion 12 formed between adjacent chip discharge grooves 6 and a coolant supply hole 7 that is formed so as to penetrate the inside of the holder body 2 and supply coolant to the tip portion of the holder body 2 are provided. ing. Further, the blade tip replaceable drill 10 includes the drill holder 1 and the cutting insert 3.
In the following description, a direction perpendicular to the direction of the axis O may be referred to as a radial direction, and a direction around the axis O may be referred to as a circumferential direction.

  The holder main body 2 is formed of steel or the like, and a base end side (upper right side in FIG. 1) in the axis O direction is a shank portion 8, and a front end side (lower left side in FIG. 1) of the shank portion 8. The blade portion 11 having a smaller diameter than the shank portion 8 is formed through a flange portion 9 having a larger diameter than the shank portion 8. The flange portion 9 has the largest diameter at the base end side, and the tip end portion of the flange portion 9 is gradually inclined inward in the radial direction along the axis O direction toward the tip end side. And is smoothly connected to the base end portion of the blade portion 11.

  This cutting edge exchanging drill 10 is configured so that the shank portion 8 of the holder main body 2 is gripped by a main spindle of a machine tool (not shown) and rotated around the axis O in the tool rotation direction T. Cut into the work material and drill the work material. As shown in FIG. 2, the tool rotation direction T in the present embodiment is a counterclockwise direction in a circumferential direction centering on the axis O when the cutting edge-replaceable drill 10 is viewed from the front end side in the axis O direction. It has become.

  In FIG. 1, the outer circumferential surface of the holder body 2 is gradually twisted toward the rear in the tool rotation direction T as it goes from the distal end of the blade portion 11 to the flange portion 9 toward the proximal end side from the distal end of the holder. The chip discharge groove 6 is formed to extend in a spiral shape. In the present embodiment, a pair of chip discharge grooves 6 are formed so as to sandwich the axis O. In the cross section perpendicular to the direction of the axis O of the chip discharge groove 6, the wall surface facing the front in the tool rotation direction T is a straight line, and the portion other than the wall surface is a concave curve (see FIG. 5).

  1 and 5, a portion of the outer peripheral surface of the holder main body 2 that is located between the chip discharge grooves 6 adjacent in the circumferential direction is a land portion 12. The land portion 12 is connected to the outer peripheral edge of the distal end surface 5 of the holder body 2 via a cross ridge line 14, and gradually twists toward the rear in the tool rotation direction T from the cross ridge line 14 toward the base end side. Thus, it is formed to extend in a spiral shape. In the present embodiment, a pair of land portions 12 are formed so as to sandwich the axis O corresponding to the pair of chip discharge grooves 6.

  The insert mounting seat 4 has a polygonal hole shape or a circular hole shape, and is formed on a wall surface facing the front in the tool rotation direction T at the tip portion of the chip discharge groove 6. In this embodiment, the insert mounting seat 4 is formed in two (a pair) in total, one for each chip discharge groove 6 so as to sandwich the axis O.

Among these insert mounting seats 4, one insert mounting seat 4 </ b> A located radially outward is formed to open in the distal end surface 5 and the land portion 12 of the holder body 2. Further, the other insert mounting seat 4 </ b> B positioned inward in the radial direction is disposed in the vicinity of the axis O and is open to the distal end surface 5 of the holder body 2.
As described above, a plurality of insert mounting seats 4 that are disposed rotationally asymmetrically with respect to the axis O are formed at the tip of the holder body 2.

  The cutting insert 3 is made of cemented carbide or the like and has a polygonal plate shape or a circular plate shape. In the present embodiment, the cutting insert 3 has a square plate shape, and the insert mounting seat 4 is formed so as to be cut into a square hole. Of the pair of square surfaces facing the thickness direction, the cutting insert 3 has a surface facing one side as a rake surface and a surface facing the other as a seating surface. Further, the side surface of the cutting insert 3 that faces the side direction perpendicular to the thickness direction is a flank surface. The intersecting ridge line between the rake face and the flank face of the cutting insert 3 is the cutting edge.

  The cutting insert 3 is formed with an attachment hole penetrating in the thickness direction. In addition, a screw hole is formed in the wall surface facing the front in the tool rotation direction T in the insert mounting seat 4. Then, the clamp screw is inserted into the mounting hole of the cutting insert 3 and the clamp screw is screwed into the screw hole of the insert mounting seat 4 so that the cutting insert 3 is detachably mounted on the insert mounting seat 4.

  In a state where the cutting insert 3 is mounted on the insert mounting seat 4, the rake face of the cutting insert 3 faces the front in the tool rotation direction T, and the seating surface faces the wall facing the front in the tool rotation direction T in the insert mounting seat 4. Sit down. In this embodiment, the cutting insert 3 mounted on one insert mounting seat 4A and the cutting insert 3 mounted on the other insert mounting seat 4B are common products having the same configuration.

  5 to 8, the cutting insert 3 mounted on one insert mounting seat 4 </ b> A has one cutting edge 3 a from the tip surface 5 to the tip among the plurality of cutting edges formed on the outer peripheral edge of the rake face. The other cutting edge 3b is protruded from the land part 12 outward in the radial direction. Further, the cutting insert 3 mounted on the other insert mounting seat 4B has one cutting edge 3a projecting from the distal end surface 5 toward the distal end side.

  1-5, the coolant supply hole 7 is arrange | positioned so as to correspond between the chip | tip discharge grooves 6 adjacent to the circumferential direction of the holder main body 2 (namely, radial direction inner side of the land part 12). In the present embodiment, a pair of coolant supply holes 7 are formed so as to sandwich the axis O corresponding to the pair of land portions 12. The coolant supply hole 7 is formed so as to gradually twist toward the rear in the tool rotation direction T from the holder front end toward the base end side.

  Although not particularly shown, these coolant supply holes 7 are opened in the base end face of the shank portion 8. In FIG. 2, one of the coolant supply holes 7 has one coolant supply hole 7 </ b> A that opens to the front end surface 5 of the holder body 2. Specifically, the one coolant supply hole 7 </ b> A is opened so as to be positioned in front of the tool rotation direction T of the one insert mounting seat 4 </ b> A on the tip surface 5 of the holder body 2. Of these coolant supply holes 7, the other coolant supply holes 7 </ b> B open to the chip discharge groove 6 toward the tip of the holder body 2. Specifically, the other coolant supply hole 7B is opened at the tip of the chip discharge groove 6 where the other insert mounting seat 4B is arranged.

  As shown in FIGS. 2, 7, and 8, a plurality of fan-shaped portions 16 are formed on the distal end surface 5 of the holder body 2 so as to be spaced apart from each other in the circumferential direction. Specifically, the front end surface 5 of the holder main body 2 is formed such that a virtual circular surface is cut out in a plurality of chip discharge grooves 6 in a circumferential shape at intervals in the circumferential direction. The remaining fan-shaped part other than the part is the fan-shaped part 16.

  In this embodiment, a pair of fan-shaped portions 16 are formed so as to sandwich the axis O corresponding to the pair of chip discharge grooves 6, and the fan-shaped portions 16 are connected and integrated so as to connect the central angle portions of each other. It has become. The fan-shaped portions 16 are different in size and shape.

  Specifically, among the pair of fan-shaped portions 16, the fan-shaped portion 16 (see FIG. 8) located in front of the tool rotation direction T of one insert mounting seat 4A is the tool rotation direction T of the other insert mounting seat 4B. It is larger than the fan-shaped part 16 (refer FIG. 7) located in front. Moreover, one coolant supply hole 7A is opened in the fan-shaped part 16 located in the front of the tool rotation direction T of one insert mounting seat 4A among the pair of fan-shaped parts 16.

  As shown in FIGS. 3 and 4, in the cross section along the axis O direction of the holder main body 2, the fan-shaped portion 16 gradually increases from the radial center (inward) toward the outer side toward the proximal end side ( It is formed to be inclined toward the lower side in FIGS. In FIG. 6, the fan-shaped portion 16 is formed so as to be gradually inclined toward the proximal end side (lower side in FIG. 6) of the holder body 2 as it goes rearward in the tool rotation direction T. Thereby, the clearance angle is given to the holder front end surface 5.

  As shown in FIGS. 2, 5, 7, and 8, a concave portion 13 is formed on the front end surface 5 of the holder body 2. The recess 13 is formed at a distance from the intersecting ridge line 14 between the tip surface 5 of the holder body 2 and the land portion 12. A plurality of recesses 13 are formed on the holder front end surface 5. In the present embodiment, these recesses 13 have a triangular hole shape, and are arranged at intervals.

  Further, the recess 13 is formed corresponding to the fan-shaped portion 16 of the holder front end surface 5. In the present embodiment, a total of two concave portions 13 (one pair) are formed, one for each fan-shaped portion 16. The recess 13 is disposed behind the insert mounting seat 4 in the corresponding fan-shaped portion 16 in the tool rotation direction T.

  As shown in FIG. 2, when the front end surface 5 of the holder main body 2 is viewed from the front, the concave portion 13 in the present embodiment has an equilateral triangle shape with three corners having an R shape. One side of the side extends substantially parallel to the cutting edge 3 a of the cutting insert 3 located in front of the recess 13 in the tool rotation direction T. Moreover, the recessed part 13 formed in the fan-shaped part 16 located ahead of the tool rotation direction T of one insert mounting seat 4A among a pair of recessed parts 13 is behind the tool rotation direction T of one coolant supply hole 7A. Has been placed.

  3 and 4, the bottom surface of the recess 13 (the back surface facing the front end side of the holder) is gradually inclined toward the base end side of the holder body 2 from the radial center (inward) toward the outer side. Is formed. Further, a concave curved surface portion 13a having a concave curved section is formed between the bottom surface of the concave portion 13 and a peripheral wall formed around the bottom surface, and the bottom surface is interposed via the concave curved surface portion 13a. And the peripheral wall are connected smoothly.

As described above, according to the drill holder 1 and the blade-tip replaceable drill 10 of the present embodiment, since the concave portion 13 is formed on the distal end surface 5 of the holder body 2, the following effects are produced.
That is, a part of the coolant supplied from the coolant supply hole 7 to the tip of the holder main body 2 passes through the gap between the holder tip surface 5 and the land portion 12 and the inner peripheral surface of the machining hole. Although it tends to flow out toward the base end side of the main body 2, the coolant stays in the recess 13 formed on the holder front end surface 5. That is, the coolant that has flowed into the recess 13 stays in the recess 13 so that the coolant is always supplied to the front end side of the holder.

  In this way, since the coolant outflow to the holder base end side is suppressed, the coolant tends to stay at the tip end portion of the holder main body 2, and accordingly, without increasing the coolant supply amount, A sufficient amount of coolant is ensured, and the wear resistance of the cutting edges 3a and 3b can be improved.

  Further, as shown in FIG. 6, the front end surface 5 of the holder main body 2 is retracted by one step from the cutting edge 3 a located on the front end side of the holder of the cutting insert 3 attached to the insert mounting seat 4. Since the clearance angle is set in the front end surface 5, a gap is also formed between the holder front end surface 5 and the bottom surface of the machining hole (the back surface facing the holder base end side). According to the present embodiment, the retention action of the recess 13 described above makes it easier for coolant to be supplied from the gap toward the cutting insert 3, and on the land portion 12 without cooling or lubricating the cutting edges 3 a, 3 b. And outflow into the chip discharge groove 6 are suppressed.

Therefore, according to this embodiment, the tool life of the cutting insert 3 can be extended, and stable cutting can be performed.
Further, according to this configuration, for example, the land portion 12 does not need to be brought into contact with the inner peripheral surface of the machining hole for the purpose of suppressing the outflow of the coolant to the holder base end side, so that the cutting resistance may be increased. Absent.

  Moreover, since the recessed part 13 is formed in the front end surface 5 of the holder main body 2 at a distance from the intersecting ridge line 14 between the front end surface 5 and the land part 12, the coolant temporarily stored in the recessed part 13. However, it is more difficult to get on the land portion 12. Specifically, for example, unlike the present embodiment, when the recess is formed to open on the intersecting ridge line 14, the coolant temporarily stored in the recess passes through the recess from the holder front end surface 5. There is a possibility that it is easy to be guided on the land portion 12 and it is easy to get on the land portion 12. On the other hand, according to the present embodiment, the recess 13 is not on the intersecting ridge line 14, that is, is not open to the land portion 12, so that the coolant can be effectively prevented from climbing from the holder front end surface 5 onto the land portion 12. .

  Further, since the recesses 13 are formed at intervals in the intersecting ridge lines 14, the coolant retained in the recesses 13 is positioned behind the tool rotation direction T instead of being difficult to go outward in the radial direction. It becomes easy to be supplied to the cutting insert 3 of the insert mounting seat 4. Therefore, the effects described above can be obtained remarkably.

  In addition, since a plurality of recesses 13 are formed, the above-described staying action by the recesses 13 is obtained at a plurality of locations on the tip surface 5 of the holder main body 2, and the amount of coolant on the holder tip side is sufficiently increased. The coolant outflow from 5 is effectively suppressed.

  In addition, a plurality of fan-shaped portions 16 are formed on the distal end surface 5 of the holder body 2 so as to be spaced apart from each other in the circumferential direction, and a chip discharge groove 6 is provided between the fan-shaped portions 16 adjacent in the circumferential direction. And an insert mounting seat 4 is formed at the tip of the chip discharge groove 6. That is, the insert mounting seat 4 is disposed behind the fan-shaped portion 16 in the tool rotation direction T, and the cutting insert 3 is mounted on the insert mounting seat 4. According to the present embodiment, since the concave portion 13 is formed corresponding to the fan-shaped portion 16, the coolant temporarily stored in the concave portion 13 is located behind the tool rotation direction T. It becomes easy to be supplied to.

  Further, in the present embodiment, at least two insert mounting seats 4 are formed at the distal end portion of the holder body 2 so as to sandwich the axis O between the radially inner side and the radially outer side. That is, among these insert mounting seats 4, the cutting speed of the cutting insert 3 mounted on one insert mounting seat 4A positioned radially outward is mounted on the other insert mounting seat 4B positioned radially inward. The cutting speed of the cutting insert 3 is increased.

And according to this embodiment, the recessed part 13 is arrange | positioned at the back of the tool rotation direction T of one coolant supply hole 7A in the fan-shaped part 16 located ahead of the tool rotation direction T of one insert mounting seat 4A. Therefore, the coolant that has flowed out of the one coolant supply hole 7A is easily captured by the recess 13 and the above-described staying action by the recess 13 causes the cutting insert 3 mounted on the one insert mounting seat 4A. A sufficient amount of coolant is secured. That is, since the coolant can be sufficiently supplied to the radially outer cutting insert 3 that requires a large amount of coolant supply with a high cutting speed, lubrication and cooling action by the coolant can be obtained more effectively. .
In this embodiment, the recess 13 is positioned not only in the fan-shaped portion 16 positioned in front of the tool rotation direction T of one insert mounting seat 4A but also in the tool rotation direction T of the other insert mounting seat 4B. Since it is formed also in the fan-shaped part 16, coolant can fully be supplied with respect to each cutting insert 3 with which these insert mounting seats 4A and 4B are mounted | worn.

  Further, the recess 13 has an equilateral triangle shape with three corners having an R shape (that is, adjacent peripheral walls are smoothly connected among the inner surfaces of the recess 13). The bottom surface and the peripheral wall are smoothly connected via the concave curved surface portion 13a. That is, the inner surface of the recess 13 is not formed with a portion such as a trough formed by crossing different planes, for example. Therefore, local stress concentration in the recess 13 is prevented, and the holder The mechanical strength of the main body 2 is ensured.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, in the above-described embodiment, the chip discharge groove 6, the land portion 12, the coolant supply hole 7, and the fan-shaped portion 16 are formed in pairs, but the chip discharge groove 6, the land portion 12, and the coolant supply. The number of the holes 7 and the fan-shaped portions 16 is not limited to the above-described embodiment.
Moreover, although the insert mounting seat 4 was formed one by one in the front-end | tip part of each chip discharge groove 6, it is not limited to the above-mentioned embodiment also about the number of insert mounting seats 4, Each chip A plurality (for example, two) of the discharge grooves 6 may be formed.

  Moreover, when the front end surface 5 of the holder body 2 is viewed from the front, the concave portion 13 has a triangular shape. However, the shape of the concave portion 13 is not limited to the above-described embodiment. That is, for example, the recess 13 may be formed in a polygonal shape other than the triangular shape, a circular shape, a groove shape, or the like. In addition, it is preferable that the inner surface of the recessed part 13 does not have the trough part formed so that planes may cross | intersect, for example, consists only of a concave curved surface, or a concave curved surface and a plane.

In addition, although the plurality of recesses 13 are formed on the front end surface 5 of the holder body 2, the present invention is not limited to this, and only one recess 13 may be formed on the front end surface 5. However, in this case, in order to sufficiently obtain the above-described staying action, it is preferable that the recess 13 is formed so as to have an opening area and a volume greater than or equal to a predetermined amount on the holder front end surface 5.
Moreover, you may form integrally so that a mutual mutual edge part may be connected by the several recessed part 13 being closely arranged.

  Moreover, in the above-mentioned embodiment, although it was supposed that the cutting insert 3 which is a common product was each mounted | worn with respect to several insert mounting seat 4A, 4B, it is not limited to this, Each insert mounting seat 4A, 4B is attached. Correspondingly, the cutting inserts 3 having different shapes may be mounted.

DESCRIPTION OF SYMBOLS 1 Drill holder 2 Holder main body 3 Cutting insert 3a, 3b Cutting blade 4 Insert mounting seat 5 End face of holder main body 6 Chip discharge groove 7 Coolant supply hole 10 Cutting edge replaceable drill 12 Land part 13 Recessed part 14 End face and land of holder main body Intersecting ridgeline with part 16 Fan-shaped part O Axis line

Claims (5)

A holder body that has an axial shape and is rotated around an axis;
An insert mounting seat on which a cutting insert having a cutting edge is detachably mounted at the distal end portion of the holder main body at least two radially inward and outward so as to sandwich the axis;
A plurality of circumferentially spaced outer peripheral surfaces of the holder body, and a chip discharge groove that opens toward the distal end surface of the holder body and includes the insert mounting seat and extends toward the proximal end side of the holder body. ,
Of the outer peripheral surface of the holder body, a land portion formed between the chip discharge grooves adjacent in the circumferential direction,
A drill holder provided with a coolant supply hole, which is formed so as to penetrate the inside of the holder body, and supplies a coolant to a tip portion of the holder body,
A drill holder characterized in that a concave portion is formed on a tip surface of the holder body. The drill holder according to claim 1,
The said recessed part is formed at intervals in the intersection ridgeline of the front end surface of the said holder main body, and the said land part, The drill holder characterized by the above-mentioned. The drill holder according to claim 1 or 2,
A drill holder, wherein a plurality of the recesses are formed. The drill holder according to claim 3,
A plurality of fan-shaped portions are formed on the front end surface of the holder body so as to be spaced apart from each other in the circumferential direction,
The said recessed part is formed corresponding to the said fan-shaped part, The drill holder characterized by the above-mentioned.   An edge-replaceable drill comprising the drill holder according to any one of claims 1 to 4 and the cutting insert.

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