JP2012171040A - Cutting edge replacement type drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drilling tool that can improve dischargeability of swarf, and improving machining accuracy.SOLUTION: This cutting edge replacement type drill includes a drill body rotating around an axis. Two swarf discharge grooves for discharging swarf cut at one end of the drill body are formed on the drill body. At an end of the one-side swarf discharge groove out of the two swarf discharge grooves, a first tip is detachably mounted at a position including the axis. At an end of the other swarf discharge groove, a second tip is detachably mounted at a position distant from the axis. The first tip discharges, to the one swarf discharge groove, swarf generated by cutting a cutting object at least at two parts distant from each other in an orthogonal direction orthogonal to the direction of the axis. The second tip discharges, to the other swarf discharge groove, swarf generated by cutting the cutting object at least at two parts distant from each other in the orthogonal direction.

Description

  The present invention relates to a blade-tip replaceable drill.

  2. Description of the Related Art There is known a blade-tip replaceable drill in which a cutting tip is mounted on one tip of a drill body that rotates about an axis. Such a blade-tip-exchangeable drill is excellent in workability and economy because the blade tip can be replaced. As such a blade-tip-replaceable drill, there is a type in which one tip is arranged so as to be biased toward the axis and the other tip is placed so as to be biased toward the outer periphery of the rotation. In this type of blade-tip-replaceable drill, an axial tip (hereinafter also referred to as an inner peripheral blade) cuts the inner peripheral side of the machining hole, and an outer peripheral tip (hereinafter also referred to as an outer peripheral blade) is the outer periphery of the processing hole. Cut the side. Chips cut by each chip are discharged from two chip discharge grooves provided for each chip. In such a blade-tip-replaceable drill, the chips are divided into two and discharged, so the width of the chips is about half the radius of the machining hole. With such a configuration, chip discharge performance is improved. Furthermore, discharge property can also be improved by making a chip fine by giving a breaker to a cutting blade.

  Furthermore, a blade tip replaceable drill that improves such a technique and discharges the chips divided into four parts is known (for example, Patent Document 1 below). In patent document 1, one chip | tip divides a chip into 2 by forming the cutting blade which provided the level | step difference in the chip | tip. In other words, since the chips are divided into four by the two chips and discharged, the chips become thinner and the chip discharge performance is further improved.

JP 2003-170308 A JP 2005-532175 A WO94 / 2772 Publication

  However, these techniques leave room for improvement in terms of processing accuracy. Specifically, in the above-described technique, the inner peripheral blade cuts the inside of the machining hole, and the outer peripheral blade cuts the outer periphery. Here, due to the characteristics of the drill, the cutting speed linearly goes to zero from the outer periphery of the processed hole toward the center of the hole. For this reason, the force which acts on an inner peripheral blade becomes larger than the force which acts on an outer peripheral blade. In this way, the rotational force is likely to occur when the acting force is biased between the inner periphery and the outer periphery. Such a problem becomes conspicuous during high-speed drilling of a drill. That is, at the time of high-speed rotation processing, there is a possibility that the processing hole becomes larger than a desired size due to rotational fluctuation. In view of at least a part of the above-described problems, the problem to be solved by the present invention is to provide a cutting edge exchanging drill that can improve chip discharging performance and machining accuracy.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1] A drill body that rotates about an axis, and two chips for discharging chips cut at a cutting end that is one end of the drill body to an attachment end that is the other end A drill body formed with a chip discharge groove, a first tip detachably mounted at a position including the axis of one of the two chip discharge grooves at the cutting end, and At the cutting end, a blade tip replaceable drill comprising a second tip detachably mounted at a position away from the axis of the other chip discharge groove of the two chip discharge grooves,
The first tip cuts a cutting object in at least two locations separated from each other in an orthogonal direction orthogonal to the direction of the axis, and discharges generated chips to the one chip discharge groove,
The second tip cuts the object to be cut at at least two points apart from each other in the orthogonal direction, and discharges the generated chips into the other chip discharge groove. Expression drill.

  According to the blade-tip-exchangeable drill having such a configuration, the chip can be divided into two by the first tip and discharged into the chip discharge groove. Similarly, the chip can be divided into two by the second chip and discharged into the chip discharge groove. Therefore, the chip dischargeability can be improved. In addition, each of the first tip and the second tip cuts the object to be cut at at least two points apart from each other in the orthogonal direction. Since all of the machining holes are formed by the first tip and the second tip, the second tip always cuts between the two places to be cut by the first tip. Similarly, between the two places to be cut with the second tip, cutting is always performed with the first tip. For this reason, when viewed along the orthogonal direction, the cutting edge-replaceable drill is designed so that a portion to be cut with the first tip and a portion to be cut with the second tip appear alternately. Will be cut. Therefore, the bias of the acting force acting on the first chip and the second chip is alleviated. As a result, it is possible to suppress the occurrence of rotational runout of the blade-tip replaceable drill and improve the processing accuracy.

[Application Example 2] The cutting edge replacement type drill according to Application Example 1, wherein a rake face which is a face facing the direction of rotation of one of the first tip and the second tip is A concave portion formed between two top portions as viewed from the orthogonal direction, and the one tip cuts the cutting object at two portions individually including the two top portions as the two locations. The other one of the first chip and the second chip includes a position at a position corresponding to the recess and a position at a position corresponding to the outside of the two top portions as the two positions. A cutting edge exchanging drill characterized by cutting the object to be cut.

  According to the blade-tip-exchangeable drill having such a configuration, each of the first tip and the second tip can suitably cut the object to be cut at at least two locations separated from each other in the orthogonal direction.

Application Example 3 The concave portion is a surface on the side of the cutting end of the one tip, and two surfaces which are a part of a flank surface continuous with the rake surface are 180 on the inner side of the flank surface. The blade-tip-replaceable drill according to Application Example 2, characterized in that it is formed so as to intersect with each other at an intersecting angle of at least 20 degrees.

  According to the blade-tip-exchangeable drill having such a configuration, the concave portion can be formed with a simple and compact shape. Therefore, manufacture is easy. In addition, when the tip is mounted on the drill body, a large restraint area of the clamp on the rake face can be secured, so that the clamp strength can be sufficiently secured.

Application Example 4 The one of the chips has a substantially 4n square (n is an integer of 3 or more) flat plate shape and is counted from any side forming the substantially 4n square including the arbitrary side. The blade tip replaceable drill according to any one of Application Example 2 and Application Example 3, wherein the first side and the (n + 1) th side are in a vertical positional relationship and have the same length.

  According to the blade-tip-exchangeable drill having such a configuration, one tip includes four parts having the same shape including n sides. For this reason, one chip can be used four times. Therefore, it is economical and contributes to resource saving.

[Application Example 5] The cutting edge replacement type drill according to Application Example 4, wherein a chip seat for holding the one chip is formed in the chip discharge groove to which the one chip is mounted, The longest side among the n sides formed is in contact with the first restraining surface that is the side surface of the chip seat, and the longest side among the n sides formed on the axis side is the side. A blade-tip-replaceable drill that is in contact with a second restraining surface that is a side surface of the tip seat.

Application Example 6 The blade tip replaceable drill according to any one of Application Examples 1 to 5, wherein the other tip has a regular rectangular flat plate shape.

  According to the blade-tip-exchangeable drill having such a configuration, the other tip has the same shape even when rotated by 90 degrees, 180 degrees, or 270 degrees. For this reason, one chip can be used four times. Therefore, it is economical and contributes to resource saving.

  The present invention can also be realized as a tip for a blade-replaceable drill, a tip set including a first tip and a second tip, a cutting method, etc., in addition to the blade-replaceable drill described above.

It is explanatory drawing which shows the external appearance of the blade-tip-exchange-type drill 20 as an Example of the blade-tip-exchange-type drill of this invention. It is explanatory drawing which shows the external appearance of the blade-tip-exchange-type drill 20. FIG. It is explanatory drawing which shows the shape of the 1st chip | tip 40 and the 2nd chip | tip 60. FIG. It is explanatory drawing which shows the rotation locus | trajectory of the 1st chip | tip 40 and the 2nd chip | tip 60. FIG. It is explanatory drawing which shows the rotation locus | trajectory of the 1st chip | tip 400a and the 2nd chip | tip 600a as a 1st comparative example. It is explanatory drawing which shows the rotation locus | trajectory of the 1st chip | tip 400a and the 2nd chip | tip 600a as a 2nd comparative example. It is explanatory drawing which shows the rotation locus | trajectory of the 1st chip | tip 140 and the 2nd chip | tip 160 as a modification.

A. Example:
A-1. Schematic configuration of the blade-tip replaceable drill 20:
An embodiment of the present invention will be described. FIGS. 1 and 2 show the appearance of a blade-tip replaceable drill 20 as an embodiment of the blade-tip replaceable drill according to the present invention. FIG. 2 is a view of the blade-tip replaceable drill 20 shown in FIG. 1 as viewed from the opposite side. The blade tip replaceable drill 20 is a throw-away tip type drill that rotates about an axis OL. As shown in FIGS. 1 and 2, the blade tip type drill 20 includes a drill body 30, a first tip 40, and a second tip 60. In the following description, a direction orthogonal to the axis OL is also referred to as an orthogonal direction OD.

  In the drill body 30, two chip discharge grooves 31 and 32 are formed from the cutting end CE of the drill body 30 toward the attachment end AE and reaching the substantially central portion. The cutting end CE is an end portion on the side where the drill body 30 cuts an object to be cut. The attachment end AE is the end opposite to the cutting end CE. The chip discharge grooves 31 and 32 discharge chips cut on the cutting end CE side of the drill body 30 to the attachment end AE side. In the present embodiment, the chip discharge grooves 31 and 32 are formed in a spiral shape along the axis OL. However, the shape of the chip discharge grooves 31 and 32 is not particularly limited. For example, the chip discharge grooves 31 and 32 may be formed in a linear shape along the axis OL.

  A first tip 40 and a second tip 60 are detachably attached to the ends of the chip discharge grooves 31 and 32 on the cutting end CE side. The first tip 40 and the second tip 60 come into contact with the object to be cut, and cut the object to be cut by rotation about the axis OL of the blade-tip replaceable drill 20.

  As shown in FIG. 2, the first chip 40 has a substantially dodecagonal flat plate shape. As shown in FIG. 1, the second chip 60 has a substantially regular rectangular flat plate shape. When viewed from the cutting end CE side, the first tip 40 and the second tip 60 are arranged substantially in a straight line in the orthogonal OD direction with the axis OL interposed therebetween. The direction in which the first chip 40 and the second chip 60 are arranged is also referred to as a first orthogonal direction OD1. The first chip 40 is disposed closer to the axis OL than the second chip 60. The second chip 60 is arranged farther from the axis OL than the first chip 40. That is, the first tip 40 cuts the inner peripheral side of the processing hole, and the second tip 60 cuts the outer peripheral side of the processing hole. For this reason, the first chip 40 is also referred to as an inner peripheral blade. The second tip 60 is also referred to as an outer peripheral blade.

  As shown in FIG. 2, a rake face 41 is formed on the front side in the rotational direction around the axis OL of the first chip 40. Further, on the cutting end CE side of the first tip 40, a flank 42 that is continuous with the rake face 41 is formed. Similarly, as shown in FIG. 1, a rake face 61 is formed on the front side in the rotational direction of the second chip 60. A flank 62 is formed on the cutting end CE side of the second tip 60. Of the orthogonal directions OD, the direction in which the rake face 41 is viewed from the front is also referred to as a second orthogonal direction OD2.

A-2. The shape of the first chip 40 and the second chip 60:
The shapes of the first chip 40 and the second chip 60 described above are shown in FIG. In FIG. 3, the cutting end CE of the blade-tip replaceable drill 20 is viewed from the orthogonal direction OD, specifically, the second orthogonal direction OD2 (see FIG. 2), which is the direction in which the rake face 41 is viewed from the front. Show. A part of the second chip 60 is shown as a perspective view. As shown in the drawing, the first tip 40 which is an inner peripheral blade is mounted in the chip discharge groove 31 at a position including the axis OL. Moreover, the 2nd chip | tip 60 which is an outer periphery blade is mounted | worn with the chip discharge groove | channel 32 (illustration omitted) in the position away from the axis line OL.

  When viewed from the second orthogonal direction OD2, the first chip 40 has a substantially dodecagonal shape having vertices V1 to V12. Here, the “corner” includes the apex of the recess. Further, “substantially” means that each vertex includes a chamfered shape. In FIG. 3, the j-th vertex (j is an integer from 1 to 12) in the clockwise direction counting from the vertex V1 including the vertex V1 is Vj. A cutting edge 49 is formed on the outer edge of the rake face 41 of the first tip 40 having such a shape. The first tip 40 is mounted in the chip discharge groove 31 so that the cutting edge 49 protrudes from the end of the drill body 30 on the cutting end CE side. A breaker may be appropriately formed on the rake face 41 and the flank face 42.

  When viewed from the second orthogonal direction OD2, the rake face 41 of the first chip 40 is attached to the chip discharge groove 31 while being inclined at a predetermined angle with respect to the first orthogonal direction OD1. Specifically, the vertex V1 is located closer to the cutting end CE than the vertex V2. In addition, the vertex V2 is located closer to the attachment end AE than the vertex V3. Further, the vertex V3 is located closer to the cutting end CE than the vertex V4. With this shape, the vertex V1 and the vertex V3 form a top portion. Hereinafter, the vertex V1 is also referred to as a top portion 43 and the vertex V3 is also referred to as a top portion 44.

  A substantially V-shaped recess 45 is formed between the top 43 and the top 44. The bottom of the recess, that is, the vertex V <b> 2 is also referred to as the bottom 46. Further, the surface formed between the vertex V1 and the vertex V2 in the flank 42 of the first chip 40 is also referred to as a surface 42a. Of the rake face 41 of the first chip 40, the face formed between the vertex V2 and the vertex V3 is also referred to as a face 42b. In this embodiment, the surface 42a and the surface 42b are flat. The recess 45 is formed by intersecting the surface 42a and the surface 42b of the flank 42 of the first chip 40 at an intersection angle θ of 180 degrees or more. The intersection angle θ is an intersection angle on the inner side of the flank 42. In other words, when viewed from the second orthogonal direction OD2, the side ridge between the vertices V1 to V2 of the rake face 41 and the side ridge between the vertices V2 to V3 are 180 degrees or more. A recess 45 is formed at the intersection.

  In the first chip 40, the shapes formed by the vertices V1 to V4 are the shapes formed by the vertices V4 to V7, the shapes formed by the vertices V7 to V10, and the shapes formed by the vertices V10 to V1, respectively. Same shape. That is, if the shape formed by the vertices V1 to V4 is rotated 90 degrees to the right, the shape is formed by the vertices V4 to V7. Similarly, if the shape of the vertices V1 to V4 is rotated 180 degrees to the right, The shape is formed by the vertices V7 to V10. When the shapes of the vertices V1 to V4 are rotated 270 degrees to the right, the shape formed by the vertices V10 to V1 is obtained. In other words, the approximate dodecagon of the first chip 40 is counted from any side forming the approximate dodecagon including the arbitrary side, and the first side and the fourth side are perpendicular to each other. It is a positional relationship and has the same length.

  When the cutting edges 49 of the vertices V1 to V4 are worn or damaged, the first chip 40 having such a shape is rotated by 90 degrees and remounted in the chip discharge groove 31 for a total of four times. Can do. Therefore, it is economical and contributes to resource saving.

  A through hole 48 is formed at the center of the rake face 41 of the first chip 40 having such a shape. The through hole 48 is a hole for inserting a clamp screw (not shown). That is, the first chip 40 is detachably attached to the chip discharge groove 31 by the clamp screw inserted into the through hole 48.

  The first chip 40 is accommodated in a chip seat 33 formed in the chip discharge groove 31. The chip seat 33 has a shape in which the inner side of the chip discharge groove 31 is cut out in order to accommodate and hold the first chip 40. Of the side surfaces of the chip seat 33, the first constraining surface 34 that is the side surface on the attachment end AE side and the second constraining surface 35 that is the side surface on the axis OL side are matched to the inclination of the first chip 40. It is formed with an inclination.

  In the state where the first chip 40 is accommodated in the chip seat 33 and attached to the chip discharge groove 31 by the clamp screw, among the three sides on the attachment end AE side formed by the vertices V7 to V10 of the first chip 40 The longest side, that is, the side formed by the vertices V9 to V10 is in contact with the first constraining surface 34. Similarly, of the three sides on the axis OL side formed by the vertices V4 to V7 of the first chip 40, the longest side, that is, the side formed by the vertices V6 to V7 is the second constraining surface 35. Abut. That is, the chip seat 33 firmly restrains the first chip 40 by contacting the first chip 40 with the first restraining surface 34 and the second restraining surface 35.

  As described above, the first chip 40 abuts on the first restraining surface 34 at the longest side among the sides on the attachment end AE side, and the second restraining surface at the longest side among the sides on the axis OL side. Since it contacts 35, it is mounted in the chip discharge groove 31 with a high restraining force. For this reason, high rigidity of the chip seat 33 including the first chip 40 is obtained, and the processing accuracy can be increased.

  The rake face 61 of the second chip 60 has a substantially square shape when viewed from the direction opposite to the second orthogonal direction OD2. A cutting edge 69 is formed on the outer edge portion of the rake face 61 of the second tip 60 having such a shape. The second tip 60 is mounted in the chip discharge groove 32 (not shown) so that the cutting edge 69 protrudes from the end of the drill body 30 on the cutting end CE side. In addition, the second chip 60 is mounted in the chip discharge groove 32 such that the rake face 61 has two opposite sides of a substantially square shape perpendicular to the axis OL. Note that breakers may be appropriately formed on the rake face 61 and the flank face 62.

  When the cutting edge 69 on one side of the substantially square shape is worn or damaged, the second tip 60 having such a shape is rotated by 90 degrees and mounted again in the chip discharge groove 32 for a total of four times. Can be reused. Therefore, it is economical and contributes to resource saving.

  A through hole 68 is formed at the center of the rake face 61 of the second chip 60 having such a shape. The through hole 68 is a hole for inserting a clamp screw (not shown). That is, the second chip 60 is detachably attached to the chip discharge groove 32 by the clamp screw inserted into the through hole 68.

  The second chip 60 is accommodated in a chip seat 36 formed in the chip discharge groove 32. The tip seat 36 has a shape in which a part of the chip discharge groove 32 on the cutting end CE side is cut away in order to receive and hold the second tip 60. Of the side surfaces of the chip seat 36, the side surface on the mounting end AE side is the angle that contacts the side on the mounting end AE side of the rake face 61 of the second chip 60 when accommodated in the second chip 60, that is, the axis OL. It is formed at an angle orthogonal to the angle. Similarly, of the side surfaces of the chip seat 36, the side surface on the axis line OL side is the angle that contacts the side on the axis line OL side of the rake face 61 of the second chip 60 when accommodated in the second chip 60, that is, the axis line It is formed parallel to OL.

  In the second tip 60, the extension line obtained by extending the side of the rake face 61 on the cutting end CE side in the orthogonal direction OD1 is between the top 43, 44 and the bottom 46 of the first tip 40 in the axis OL direction. It mounts | wears with the chip discharge groove | channel 32 so that it may be located in.

A-3. Rotation locus of the first chip 40 and the second chip 60:
FIG. 4 shows the rotation trajectory between the flank 42 of the first chip 40 and the flank 62 of the second chip 60 described above. FIG. 4 is a locus diagram viewed from the second orthogonal direction OD2, that is, the direction in which the rake face 41 is viewed from the front. In the drawing, a locus corresponding to the rotation radius r about the axis OL of the first chip 40 and the second chip 60 is shown. As illustrated, the position of the end portion on the cutting end CE side of the second tip 60 in the axis OL direction is located between the top portions 43 and 44 and the bottom portion 46 of the first tip 40.

  For this reason, the cutting with the blade tip type drill 20 is performed as follows. First, the first tip 40 located on the cutting end CE side with respect to the second tip 60 comes into contact with the object to be cut, and a portion including the top 43 and a portion including the top 44 in the orthogonal direction OD. The cutting objects in the inner peripheral cutting areas IA1 and IA2 that are separated from each other are cut.

  After that, when the cutting surface of the cutting object reaches the position of the second chip 60, the second chip 60 positioned on the attachment end AE side of the first chip 40 cuts the remaining part of the cutting object. To do. Specifically, since the first tip 40 has already cut the inner peripheral cutting region IA1 and the region A3 in the locus of the second tip 60, the second tip 60 is in this region. The object to be cut is not cut. That is, the second tip 60 swings the inner peripheral cutting area IA1 and the area A3. Therefore, as a result, the second chip 60 is positioned between the portion on the outer peripheral side (opposite side to the axis OL) from the first chip 40 and the top 43 and the top 44 of the first chip 40. The cutting object in the outer peripheral edge cutting regions OA1 and OA2 separated from each other in the orthogonal direction OD is cut by a portion corresponding to the portion including the bottom portion 46 to be cut.

  Thus, the 1st chip | tip 40 cuts a cutting target object in the inner peripheral blade cutting area | region IA1 and IA2 which were mutually separated in orthogonal direction OD. The chips cut in the inner peripheral cutting areas IA1 and IA2, that is, the chips divided into two, are discharged into the chip discharge groove 31. Similarly, the second tip 60 cuts the object to be cut in the outer peripheral edge cutting areas OA1 and OA2 that are separated from each other in the orthogonal direction OD. Chips cut in the peripheral edge cutting areas OA1 and OA2, that is, chips divided into two parts are discharged into the chip discharge groove 32.

A-4. effect:
The above-described blade-tip-replaceable drill 20 can divide the chips into two by the first tip 40 and discharge them into the chip discharge groove 31. Similarly, the chip can be divided into two by the second chip 60 and discharged into the chip discharge groove 32. Therefore, the chips become thinner and the discharge property can be improved. Moreover, the first tip 40, which is the inner peripheral blade, cuts the cutting object at two locations in the inner peripheral blade cutting areas IA1, IA2 that are separated from each other in the orthogonal direction OD. Similarly, the second tip 60, which is an outer peripheral blade, cuts the cutting object at two locations in the outer peripheral blade cutting areas OA1 and OA2 that are separated from each other. For this reason, when viewed along the orthogonal direction OD from the outer peripheral side to the axis OL side, the blade-tip replaceable drill 20 cuts the cutting target object by arranging the outer peripheral blade, the inner peripheral blade, the outer peripheral blade, and the inner peripheral blade. Will be. Therefore, the bias of the acting force acting on the inner peripheral blade and the outer peripheral blade is alleviated. As a result, it is possible to suppress the occurrence of rotational shake of the blade tip replaceable drill 20 and improve the processing accuracy. For example, even if the blade-tip replaceable drill 20 is used at high speed rotation, it is possible to perform cutting with high accuracy while suppressing rotational shake.

  On the other hand, such an effect cannot be obtained with the cutting edge replacement drill as a comparative example. FIG. 6 shows the trajectories of the first tip 400a and the second tip 600a of the blade-tip-exchangeable drill as the first comparative example. In this example, the first tip 400a that is an inner peripheral blade relatively cuts the inner peripheral blade cutting area IA11 on the inner peripheral side. The second tip 600a, which is an outer peripheral blade, cuts the outer peripheral blade cutting area OA11 on the relatively outer peripheral side. That is, since the first chips 400a and 600b each generate one chip, the chip dischargeability is poor as compared with the cutting edge replaceable drill 20 of the present application.

  Moreover, the locus | trajectory of the 1st chip | tip 400b of the blade-tip-exchange-type drill as a 2nd comparative example and the 2nd chip | tip 600b is shown in FIG. In this example, the first tip 400b, which is an inner peripheral blade, includes a curved portion 410b that is curved in an S shape. For this reason, the chips cut by the first tip 400b are divided into two parts by the inner peripheral cutting area IA21 on the outer peripheral side of the bending portion 410b and the inner peripheral cutting area IA22 on the axis OL side of the bending portion 410b. Is discharged.

  Similarly, the 2nd chip | tip 600b which is an outer periphery blade is provided with the curved part 610b curved in S shape. For this reason, the chips cut by the second chip 600b are divided into two parts by the outer peripheral cutting area OA21 on the outer peripheral side of the bending portion 610b and the outer peripheral cutting area OA22 on the axis OL side of the bending portion 610b. Discharged.

  Thus, in the second comparative example, chips are divided into four parts and discharged. For this reason, in the 2nd comparative example, the chip | tip discharge | emission property is improving compared with the 1st comparative example. However, when viewed along the orthogonal direction OD from the outer peripheral side to the axis OL side, in this example, the first tip 400a and the second tip 600b are the outer peripheral blade, the outer peripheral blade, the inner peripheral blade, and the inner periphery. The object to be cut is cut with the blades. According to such a configuration, during cutting, a large force acts on the inner peripheral blade in a biased manner compared to the outer peripheral blade, so that rotational shake is likely to occur. For this reason, there is a possibility that the processed hole becomes larger than a desired size due to the rotational vibration generated during the processing. According to the cutting edge replaceable drill 20 of the present application, occurrence of such a problem can be effectively suppressed.

  Further, in the above-described blade-tip replaceable drill 20, in the first tip 40, the surface 42a and the surface 42b of the flank 42 are crossed at a crossing angle θ of 180 degrees or more with respect to a general square tip, Only the shape in which the recessed part 45 is formed is given. For this reason, the shape of the rake face 41 can be simplified. Therefore, the manufacture of the first chip 40 is easy. Such an effect is also achieved when a shape in which the above-described recess is formed is given to a chip having another shape, for example, a general diamond-shaped chip. Moreover, a large restraint surface for mounting the first chip 40 on the first restraint surface 34 and the second restraint surface 35 can be secured, and a sufficient strength of the clamp can be secured. On the other hand, if the chip shape is complicated, the area of the two surfaces to be constrained must be reduced, and the clamp strength may not be obtained.

  The blade tip replaceable drill 20 includes two separated tips, that is, a first tip 40 that is an inner peripheral blade and a second tip 60 that is an outer peripheral blade. For this reason, different materials can be used for the inner peripheral blade and the outer peripheral blade. Specifically, a material that can withstand high speed machining can be used for the outer peripheral blade, and a material that can withstand low speed and high load can be used for the inner peripheral blade. Thus, if the material according to the difference in the characteristic of the inner peripheral side and outer peripheral side of a drill is used, the high functionalization and lifetime improvement of the blade-tip-exchange-type drill 20 can be achieved.

B. Variations:
B-1: Modification 1:
In the above-described embodiment, the configuration in which the recesses 45 are formed by intersecting the surfaces 42a and 42b of the flank 42 of the first chip 40 at an intersection angle θ of 180 degrees or more is described. What is necessary is just to set a shape suitably. The concave portion only needs to have a shape in which a part of the portion acting as the cutting blade 49 is recessed toward the attachment end AE side when viewed from the direction in which the rake face 41 is viewed from the front.

  A modification of the recess is shown in FIG. FIG. 7 shows rotation trajectories of the first chip 140 and the second chip 160 as a modification. In this example, the first chip 140 is arranged such that the flank 142 of the first chip 140 is in a positional relationship parallel to the flank 162 of the second chip 160. That is, the first chip 140 is installed such that the flank 142 is parallel to the orthogonal direction OD. In the first chip 140, a substantially U-shaped recess 145 is formed between the tops 143 and 144.

  The height of the flank 162 of the second tip 160 in the axis OL direction is set at a position higher than the bottom 146 of the recess 145 and lower than the tops 143 and 145 with respect to the attachment end AE side. Similar to the embodiment, the first tip 140 cuts the object to be cut at the two inner peripheral edge cutting regions IA1 and IA2 that are separated from each other in the orthogonal direction OD. Similarly, the 2nd chip | tip 160 cuts a cutting target object in the outer peripheral blade cutting area | region OA1 and OA2 which were mutually separated in orthogonal direction OD. Even in this case, the chip can be divided into four parts in the same manner as in the embodiment to improve the chip dischargeability. Moreover, the bias of the acting force acting on the inner peripheral blade and the outer peripheral blade can be reduced.

B-2: Modification 2:
In the above-described embodiment, at one mounting position of the first tip 40, there is one recess formed at a location that acts as the cutting edge 49 of the first tip 40. However, two or more recesses may be formed in the first chip 40. If it carries out like this, a chip can be divided | segmented further finely and the discharge property of a chip can be improved more. For example, when two concave portions are formed, the first chip 40 divides the chips into three.

B-3: Modification 3:
When the recess is formed in a substantially U shape as in Modification 1 or when the recess is formed in two or more as in Modification 2, the shape of the rake face of the first chip is approximately 4n square ( n may be any integer of 4 or more. Here, the first side and the (n + 1) th side are in a vertical positional relationship and counted from any side that forms a substantially 4n square, including the arbitrary side, and have the same length. Thus, the shape of the rake face is preferably formed. In this way, the first chip can be used four times as in the above-described embodiment. The above-described embodiment is a case where n = 3. However, the number of times the first chip is used may be set as appropriate. For example, the shape of the rake face of the first chip may be a substantially 3n square and may be used three times.

  Further, in this case, the longest side of the n sides formed on the attachment end AE side of the approximately 4n square is the first restraining surface 34 of the chip seat 33 formed in the chip discharge groove 31. The longest side among the n sides formed on the axis OL side may be in contact with the second restraining surface 35 of the chip seat 33. If it carries out like this, the chip | tip seat 33 can restrain a 1st chip | tip firmly like an Example.

B-4: Modification 4:
In the above-described embodiment, the inner peripheral blade (for example, the first chip 40) is configured to include the concave portion, but the chip in which the concave portion is formed between the two top portions may be the outer peripheral blade. In this case, if the height of the flank of the inner peripheral blade in the direction of the axis OL is higher than the bottom of the recess formed in the outer peripheral blade with respect to the attachment end AE side, it is set at a position lower than the two tops. Good. Even in this case, each of the inner peripheral blade and the outer peripheral blade can cut the object to be cut at two positions separated from each other in the orthogonal direction OD.

  Of course, the configuration in which the inner peripheral blade and the outer peripheral blade cut the object to be cut at two positions apart from each other in the orthogonal direction OD can also be realized in a shape other than the concave portion. For example, instead of the inner peripheral blade including the concave portion, the outer peripheral blade may include a convex portion protruding toward the cutting end CE. In this case, what is necessary is just to set it as the structure which the convex part of an outer peripheral blade cuts between the area | regions which an inner peripheral blade cuts. Alternatively, the inner peripheral blade may be provided with a convex portion that protrudes toward the cutting end CE. In this case, what is necessary is just to set it as the structure which the convex part of an inner peripheral blade cuts between the area | regions which an outer peripheral blade cuts. Of course, depending on the height relationship between the inner peripheral blade and the outer peripheral blade in the axis OL direction, either the inner peripheral blade or the outer peripheral blade may be provided with a concave portion, and the other may be provided with a convex portion. In this case, it is desirable that the concave portion and the convex portion are arranged in a reversed manner. Alternatively, the inner peripheral blade and / or the outer peripheral blade may have both a concave portion and a convex portion.

  As mentioned above, although embodiment of this invention was described, elements other than the element corresponding to the element described in the independent claim among the components in embodiment mentioned above are additional elements, are abbreviate | omitted suitably, or Combinations are possible. In addition, the present invention is not limited to such an embodiment, and it is needless to say that the present invention can be implemented in various modes without departing from the gist of the present invention. For example, the present invention can be realized as a tip for a blade-tip replaceable drill, a tip set including a first tip and a second tip, a cutting method, or the like in addition to the blade-tip replaceable drill described above.

DESCRIPTION OF SYMBOLS 20 ... Blade-replaceable drill 30 ... Drill main body 31, 32 ... Chip discharge groove 33, 36 ... Tip seat 34 ... First restraint surface 35 ... Second restraint surface 40, 140 ... First tip 41 ... Rake surface 42 42a, 42b, 142 ... Flank 43, 44, 143, 144 ... Top 45, 145 ... Recess 60, 160 ... Second tip 61 ... Rake face 62 ... Flank OL ... Axis OD ... Orthogonal direction OD1 ... First Orthogonal direction OD2 ... second orthogonal direction CE ... cutting end AE ... mounting end

Claims (6)

A drill body that rotates about an axis, and is formed with two chip discharge grooves that discharge chips cut at a cutting end that is one end of the drill body to an attachment end that is the other end. A drill body, a first tip detachably mounted at a position including the axis of one of the two chip discharge grooves at the cutting end, and the cutting end, A blade tip replaceable drill comprising a second tip detachably mounted at a position away from the axis of the other chip discharge groove of the two chip discharge grooves,
The first tip cuts a cutting object in at least two locations separated from each other in an orthogonal direction orthogonal to the direction of the axis, and discharges generated chips to the one chip discharge groove,
The second tip cuts the object to be cut at at least two points apart from each other in the orthogonal direction, and discharges the generated chips into the other chip discharge groove. Expression drill. The blade tip replaceable drill according to claim 1,
The rake face, which is the face facing the direction of rotation of one of the first chip and the second chip, includes a recess formed between two top portions when viewed from the orthogonal direction. ,
The one tip cuts the object to be cut at two parts including the two top parts as the two places,
The other one of the first chip and the second chip is a portion at a position corresponding to the concave portion and a portion at a position corresponding to the outside of the two top portions as the two locations. A cutting edge replaceable drill characterized by cutting the object to be cut.   The recess is a surface on the side of the cutting end of the one tip, and two surfaces which are a part of a flank surface connected to the rake surface have an intersecting angle of 180 degrees or more on the inner side of the flank surface. The blade tip replaceable drill according to claim 2, wherein the drill is exchanged so that   The one chip has a substantially 4n square (n is an integer of 3 or more) flat plate shape, and the first side is counted from any side forming the substantially 4n square including the arbitrary side. The blade tip replaceable drill according to any one of claims 2 and 3, wherein the n + 1th side is in a vertical positional relationship and has the same length. The blade-tip-exchangeable drill according to claim 4,
In the chip discharge groove for mounting the one chip, a chip seat for holding the one chip is formed,
The longest side among the n sides formed on the attachment end side is in contact with the first restraining surface which is the side surface of the chip seat,
The longest side of the n sides formed on the axis side is in contact with a second restraining surface that is a side surface of the tip seat.   The blade tip exchange drill according to any one of claims 1 to 5, wherein the other tip has a regular rectangular flat plate shape.

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