JP2010167539A - Drill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drill capable of achieving efficient coolant supply through a coolant hole. <P>SOLUTION: A pair of chip discharge grooves are formed at an outer circumference of a tip part of a drill body 1 rotated around an axis O, and the rear end of the drill body 1 is made to be a shank part 2. The coolant hole 10 is formed to pass through between the chip discharge grooves from the rear end of the shank part 2 to a tip side. The coolant hole 10 extends in a direction gradually separating from an axis O as it goes toward the tip side in a part at least from the rear end of the shank part 2 to the tip end. The diameter of the pitch circle P of the coolant hole passing through the center lines C of the coolant holes 10 with the axis O as a center in a cross section orthogonal to the axis O is increased more in a part where the coolant hole 10 is opened at the tip side of the drill body 1 than in a part where the coolant hole 10 is opened at the rear end of the shank part 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a drill with a coolant hole capable of drilling a work material while supplying coolant from a coolant hole formed in a drill body.

  In a so-called two-blade drill, such a coolant hole is formed along the axis of the drill body when the core thickness of the drill body, which is the distance between the groove bottoms of the chip discharge groove, is sufficiently large. In general, it is branched in a Y shape on the side, and opened to the tip flank surface connected to the cutting edge. However, if the depth of the chip discharge groove is increased to improve the chip discharge performance, the core thickness is reduced. Therefore, if the coolant hole is formed along the axis, the rigidity and strength of the drill body are impaired.

  Therefore, for example, in Patent Documents 1 and 2, in the shank portion on the rear end side of the drill body attached to the main shaft of the machine tool, one coolant hole is formed so as to extend along the axis, while a chip discharge groove is formed. In the tip portion, the coolant hole is branched into two and formed to extend to the tip side through a portion between the chip discharge grooves in the circumferential direction. Further, in Patent Documents 3 and 4, a pair of coolant holes are formed from the rear end of the shank portion so as to pass through the portion between the chip discharge grooves and to extend toward the front end side in parallel with the axis. What has been proposed.

JP-A-6-182613 Japanese Patent No. 3801210 Japanese Patent Laid-Open No. 11-19812 JP 2004-130411 A

  However, as in the drills described in Patent Documents 1 to 4, at least in the shank portion of the drill body, the coolant hole extends along the axis or parallel to the axis toward the tip side. If the supply pressure of the coolant from the machine side is insufficient, the coolant may stay in the shank portion and may not be efficiently supplied to the cutting site by the cutting edge on the tip side.

  In this respect, for example, in the drills described in Patent Documents 2 and 3, the coolant hole is oriented obliquely with respect to the axis on the tip side of the shank portion, and centrifugal force acts on the coolant on the tip side. However, since the coolant staying in the portion extending in the axial direction on the rear end side than this is only sent to the front end side by the negative pressure of the coolant supplied to the front end side due to this centrifugal force, An efficient supply cannot be desired.

  Further, when the coolant holes are branched into two in the drill body as in Patent Documents 1 and 2, when the branch position is shifted in the axial direction, the coolant holes are supplied to the branched coolant holes. The coolant supply pressure may change. On the other hand, if the coolant holes extend between the chip discharge grooves parallel to the axis as in Patent Documents 3 and 4, the twist angle of the chip discharge grooves cannot be increased, and chip discharge performance is impaired. .

  The present invention has been made under such a background, and in a drill formed so that a coolant hole extends between the chip discharge grooves, the coolant can be supplied more efficiently through the coolant hole. The aim is to provide a drill that can.

  In order to solve the above problems and achieve such an object, according to the present invention, a pair of chip discharge grooves extending in the axial direction are spaced apart in the circumferential direction on the outer periphery of the tip of the drill body rotated about the axis. Cutting edges are provided at the front ends of the wall surfaces of the chip discharge grooves facing the drill rotation direction, and the rear end portion of the drill body is formed as a shank portion from the rear end of the shank portion. A coolant hole is formed so as to pass between the chip discharge grooves in the circumferential direction toward the tip side of the drill body, and the coolant hole is at least a portion from the rear end of the shank portion toward the tip side. In this case, the coolant hole pin extends in a direction gradually separating from the axis line toward the tip side, and passes through the center of the coolant hole centering on the axis line in a cross section orthogonal to the axis line. The diameter of Ji circle, the coolant hole is characterized in that it is larger at the portion which opens to the distal end side of the drill body than the portion which opens at the rear end of the shank portion.

  In the drill configured in this way, the coolant hole extends in a direction gradually separating from the axis as it goes to the tip side at least at a portion from the rear end of the shank portion toward the tip side. The coolant supply pressure does not change as in the case where the coolant hole extending along the axis is branched, and the centrifugal force is quickly applied to the coolant supplied to the shank from the machine tool side to the tip side. Can be pumped.

  Moreover, the coolant hole has a diameter of the coolant hole pitch circle passing through the center of the coolant hole in a circle centering on the axis in a cross section orthogonal to the axis, the tip of the drill body being more than the portion opening at the rear end of the shank. Since it is enlarged at the portion opening to the side, the coolant discharge pressure from the tip of the drill body can be surely made higher than the supply pressure at the rear end of the shank. Accordingly, it is possible to efficiently supply the coolant to the cutting site by the cutting blade.

  Here, the coolant hole is formed so as to extend in a straight line or a broken line formed of multi-stage bent lines, thereby facilitating the formation of the coolant hole in the drill body, and particularly formed so as to extend in a broken line. In this case, even if the twist angle of the chip discharge groove is large, this can be dealt with.

  Further, the coolant hole may extend in a direction gradually separating from the axis as it goes toward the tip side over the entire length of the drill body, but on the tip side of the drill body away from the shank part, it may be partially or entirely In particular, it may have a portion extending in a direction parallel to the axis or in a direction approaching the axis as it goes toward the tip side. However, in this case, it is desirable that the inner diameter of the coolant hole in this portion is smaller than the inner diameter of the portion extending in a direction gradually separating from the axis from the rear end to the front end side of the shank portion. More efficient supply can be achieved without impairing the discharge pressure of the coolant.

  As described above, according to the present invention, the coolant supplied from the machine tool side is quickly pressurized by centrifugal force without being retained in the shank portion and fed to the tip side, and is high from the tip side of the drill body. It is possible to efficiently supply the cutting portion with the cutting edge with the discharge pressure, and it is possible to promote smooth drilling by ensuring cooling and lubrication of the cutting blade and the work material at the cutting portion.

It is a perspective view which shows one Embodiment of this invention. It is a top view of embodiment shown in FIG. It is a side view of embodiment shown in FIG. It is a front view of embodiment shown in FIG. It is a rear view of embodiment shown in FIG. It is YY sectional drawing in FIG.

  In this embodiment, the drill body 1 is integrally formed in a substantially multi-stage columnar shape centering on the axis O with a steel material or the like, and the rear end side (the right side in FIGS. 2 and 3) is the shank portion 2. Further, a cutting edge portion 3 is formed on the distal end side (left side in FIGS. 2 and 3) via a flange portion 4. A pair of chip discharge grooves 5 are formed on the outer periphery of the cutting edge portion 3 on the opposite sides of the axis O, open to the tip flank 6 of the drill body 1 and move in the drill rotation direction T toward the rear end side. It is formed to reach the flange 4 so as to be twisted toward the rear side.

  In the present embodiment, insert mounting seats 7 are formed at the tips of the wall surfaces of the chip discharge grooves 5 facing the drill rotation direction T so as to open to the tip flank 6, respectively. A cutting insert 8 made of a hard material such as cemented carbide is detachably attached with its cutting edge 9 protruding from the tip flank 6. The insert mounting seat 7 and the cutting insert 8 are arranged so as to be shifted from the inner peripheral side and the outer peripheral side of the drill body 1, and the rotation trajectories around the axis O of the cutting edges 9 overlap each other. Form holes in the material.

  Further, in the drill body 1, a pair of coolant holes 10 extend from the rear end surface of the shank portion 2 toward the front end side and reach the cutting edge portion 3 beyond the flange portion 4. And extending so as to pass between the chip discharge grooves 5 in the circumferential direction, and penetrating through the tip flank 6 so as to open to the rear side in the drill rotation direction T of each insert mounting seat 7. As shown in FIG. 2, these coolant holes 10 extend at least in a portion from the rear end to the front end side of the shank portion 2 and gradually away from the axis O toward the front end side.

  That is, in the present embodiment, these coolant holes 10 have a circular cross section, and are opened at the rear end face of the shank portion 2 at a symmetrical position with respect to the axis O, from the open end to the front end side of the rear end face. While maintaining a constant cross-sectional shape, each is gradually separated from the axis O so as to extend in the drill rotation direction T and extends linearly. However, these coolant holes 10 are asymmetric with respect to the axis O as shown in FIGS. 4 and 5 at portions other than the opening end on the rear end face.

  Further, the coolant hole 10 extending to the tip side while being separated from the axis O in this way is slightly reduced in diameter by one step at a position before reaching the tip flank 6 (position of the YY cross section in FIG. 3). The portion of the end face that extends linearly from the opening end is bent at an obtuse angle in the drill rotation direction T side, and is linearly extended away from the axis O and opened to the tip flank 6. That is, it is formed in a polygonal line shape. In this embodiment, the coolant hole 10 thus opened to the front flank 6 is also disposed at a symmetrical position with respect to the axis O, but the radial distance from the axis O is the open end on the rear end surface of the shank portion 2. It is larger than the interval.

  That is, the center line C of each coolant hole 10 having a circular cross section is located on one coolant hole pitch circle P centered on the axis O at the opening end of the rear end surface of the shank portion 2 and the opening end of the front end flank 6. The diameter D of the coolant hole pitch circle P is larger than the diameter D1 of the coolant hole pitch circle P on the rear end face shown in FIG. D3 is made large.

  In the present embodiment, even at the position of the YY cross section where the coolant hole 10 bends, the center line C of the coolant hole 10 is on one coolant hole pitch circle P centered on the axis O as shown in FIG. Further, the diameter D2 is larger than the diameter D1 and substantially equal to the diameter D3. However, the pair of coolant holes 10 are not disposed at symmetrical positions with respect to the axis O as shown in FIG.

  In the drill constructed as described above, the shank portion 2 is held on the main spindle of the machine tool, and coolant is supplied from the machine tool side to the coolant hole 10 opened in the rear end face, and the drill body 1 is rotated around the axis O. When the drill hole is rotated at a high speed in the drill rotation direction T, the coolant hole 10 extends in a direction away from the rear end surface with respect to the axis O, so that centrifugal force acts quickly on the supplied coolant. As a result, pressure is applied to the tip side to feed the coolant.

  The diameter D of the coolant hole pitch circle P, which is the radial distance between the coolant holes 10 with respect to the axis O, has diameters D2 and D3 on the front end side larger than the diameter D1 on the rear end side. Since the diameter D3 of the coolant hole pitch circle P on the flank 6 is larger than the diameter D1 of the coolant hole pitch circle P on the rear end surface of the shank portion 2, the supply pressure of the coolant supplied in this way is impaired. However, the coolant can be ejected from the tip flank 6 with a high pressure, and can be efficiently supplied to the cutting edge 9 or the cutting part of the workpiece, that is, the bottom of the machining hole. For this reason, while being able to cool and lubricate these cutting blades 9 and a work material effectively, it also becomes possible to discharge | emit chips smoothly through the chip discharge groove | channel 5 with the coolant supplied by the high voltage | pressure, and stable hole. Dawn processing can be achieved.

  Further, in the present embodiment, the coolant hole 10 extends linearly from the rear end surface of the shank portion 2 toward the front end side, then bends at the front end side, extends again linearly, and opens to the front end flank 6. It is formed in a polygonal line shape, and when the chip discharge groove 5 is twisted around the axis as in this embodiment, even if the twist angle is large or the twist angle is changed in the middle, The coolant hole 10 can be formed easily corresponding to this. In addition, since the coolant holes 10 in each part are linear, it is easy to form the coolant holes 10 themselves.

  Furthermore, in the present embodiment, the tip side portion of the coolant hole 10 thus formed in a polygonal line has a slightly smaller inner diameter than the rear end side portion extending from the rear end surface of the shank portion 2, and the tip flank 6. Therefore, the coolant sprayed from the tip flank 6 can be further pressurized and supplied to the cutting edge 9 and the cutting site of the work material more efficiently. In addition, since the coolant is further pressurized in the tip side portion in this way, the coolant hole 10 in this portion extends in parallel with the axis O, or partially or entirely moves toward the axis O toward the tip side. It may extend in the approaching direction.

  However, in the present embodiment, the coolant hole 10 is formed in the shape of a polygonal line formed by bending in multiple stages as described above. However, when the twist angle of the chip discharge groove 5 is gentle, the shank portion 2 is viewed from the rear end surface. You may form so that it may space apart from the axis line O, extending in a straight line until it reaches the tip flank 6. Further, in the present embodiment, the pair of coolant holes 10 are opened on the rear end surface of the shank portion 2 so as to be positioned on the coolant hole pitch circle P, for example, along the conventional axis O. For example, when used in a machine tool for supplying coolant to a drill with a coolant hole formed, a shallow spot face is formed on the rear end surface of the shank portion 2 in the range including the open ends of the pair of coolant holes 10 around the axis O. And you may make it the coolant hole 10 open in the bottom face.

  Further, in the present embodiment, the pair of coolant holes 10 are the coolant holes having the same diameters D1 to D3 at the rear end surface of the shank portion 2, the position of the YY cross section where the coolant hole 10 bends, and the front end flank 6. Although the center is located on the pitch circle P, these coolant holes 10 may be on different coolant hole pitch circles P at each position in the axis O direction, and in some cases, one coolant hole. 10 extends at least in the direction from the rear end to the front end side of the shank portion 2 and gradually away from the axis O toward the front end side, and the diameter of the coolant hole pitch circle P opens to the rear end of the shank portion 2. It may be made larger at the portion that opens to the tip flank 6 than the portion that does.

DESCRIPTION OF SYMBOLS 1 Drill main body 2 Shank part 3 Cutting edge part 5 Chip discharge groove 6 Tip flank 9 Cutting edge 10 Coolant hole O Axis line of drill main body T Drill rotation direction C Center line of coolant hole 10 P Coolant hole pitch circle D1-3 Coolant Diameter of hole pitch circle P

Claims (3)

  A pair of chip discharge grooves extending in the axial direction are formed on the outer periphery of the tip end of the drill body rotated about the axis at intervals in the circumferential direction, and these chip discharge grooves are formed at the end of the wall surface facing the drill rotation direction. Cutting edges are provided respectively, and the rear end portion of the drill main body is a shank portion. From the rear end of the shank portion toward the front end side of the drill main body, a coolant hole is formed in the chip discharge groove in the circumferential direction. The coolant hole extends in a direction gradually separating from the axial line toward the front end side at least in a portion from the rear end to the front end side of the shank portion. The diameter of the coolant hole pitch circle passing through the center of the coolant hole with the axis as the center in an orthogonal cross section is such that the coolant hole opens at the rear end of the shank portion. Drill characterized in that it is larger at the portion which opens to the distal end side of the drill body than minute.   2. The drill according to claim 1, wherein the coolant hole extends in a straight line shape or a broken line shape composed of multiple straight lines.   The coolant hole has a portion extending in a direction parallel to the axis line or a direction approaching the axis line toward the tip side on the tip side of the drill body, and in this portion, the coolant hole The drill according to claim 1 or 2, wherein an inner diameter is made smaller than an inner diameter of a portion from the rear end of the shank portion toward the front end side.

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