JP2011125941A - Drill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drill preventing the chip discharging property from being impaired while sufficiently ensuring the strength and the rigidity of a drill body at a blade tip part even when the drill has a small diameter and a large ratio of L/D. <P>SOLUTION: Only one chip discharging groove 4 consisting of a main groove 7 and a sub groove 8 continuous to a forward side in the drill rotating direction extends from a fore end of the blade tip part 2 to its rear end side. A cutting blade 6 is formed on a cross-ridge part between a face to the forward side of the drill rotating direction 7 of the main groove 7 with a fore end flank 5. The sub groove 8 has the predetermined depth to the maximum outside diameter D of the blade tip part 2 formed by the cutting blade 6, and the main groove 7 has the depth larger than that of the sub groove 8 at the fore end flank 5. The groove depth is gradually smaller toward the rear end side of the blade tip part 2, and almost flat on the fore end side from the rear end of the sub groove 8. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a drill used for drilling a work material, and in particular, drilling a hole portion of a small diameter deep hole in a work material such as a printed circuit board, a minute metal part, or plastic. The present invention relates to a small-diameter drill used in the above.

  As such a small-diameter drill, for example, in Patent Document 1, there is only one chip discharge groove and it is formed so as not to include the rotation axis of the drill body, and the most distal side in the axial direction on the tip flank A drill has been proposed in which the leading edge projecting at a point is composed of one point, and the distance between the leading edge and the axis is less than (5/100) D with respect to the maximum outer diameter D of the cutting edge. Yes. Furthermore, in this patent document 1, it is connected to the drill rotation direction front side of a chip discharge groove, and while extending from the front-end | tip of a blade edge part toward a rear-end side, it is also possible to form the sub-groove part which cuts into a chip discharge groove in the middle. As described above, it has been proposed to reduce the labor and time during re-polishing by forming such a sub-groove portion to reduce the tip flank.

JP 2004-82318 A

  However, in the drill described in Patent Document 1, although the chip discharge groove does not include the axis of the drill body as described above, a hole is formed in the intersecting ridge line portion between the wall surface facing the front side in the drill rotation direction and the tip flank surface. In order to form a cutting blade having a length necessary for performing the drilling process, a certain groove depth is required. Accordingly, such a chip discharge groove extends toward the rear end side of the blade edge portion with the groove depth as it is, and for example, the groove length, that is, the effective cutting edge length L of the blade edge portion is relative to the maximum outer diameter D. The ratio L / D to be made is set to 5 or more, which may make it difficult to sufficiently ensure the strength and rigidity of the drill body on the rear end side of the blade edge portion.

  Further, like the chip discharge groove, the sub-groove portion extends while twisting toward the rear end side from the tip end of the blade tip portion in the direction of drill rotation, and is twisted at the undercut portion on the tip end side of the blade tip portion. By sharply increasing the angle, it is designed to cut up on the wall facing the rear side of the drill rotation direction of the chip discharge groove, and although it has the effect of facilitating re-polishing as described above, the chip discharge performance is improved. There is little to contribute to. Rather, because the groove width of the sub-groove portion suddenly decreases at the portion that cuts to the wall surface of the chip discharge groove, for example, when the copper foil thickness is thick in the drilling process of a printed circuit board to which copper foil or the like is attached, There also existed a problem that generation | occurrence | production of the chip clogging by the chip of this copper foil cannot be avoided.

  The present invention has been made under such a background, and even in a drill having a small diameter and a large ratio L / D, while ensuring sufficient strength and rigidity of the drill body at the cutting edge portion, chip dischargeability is achieved. The purpose is to provide a drill that does not damage it.

  In order to solve the above-described problems and achieve such an object, the present invention provides a main groove on the outer periphery of the tip of the drill body rotated about the axis, and a front of the main groove in the drill rotation direction. A single chip discharge groove composed of a secondary groove on the side is formed so as to extend from the front end of the blade edge part toward the rear end side, and the drill rotation direction of the main groove in the chip discharge groove A cutting edge is formed at the intersecting ridge line portion between the surface facing the front side and the tip flank surface of the blade edge portion, and the sub-groove is formed on the tip edge with respect to the maximum outer diameter of the blade edge portion formed by the cutting blade. While the fixed groove depth is made from the flank face toward the rear end side of the cutting edge portion, the main groove has a groove depth deeper than the groove depth of the auxiliary groove at the tip flank face, and the cutting edge. The groove depth gradually becomes shallower toward the rear end side of the section, and the tip end is farther than the rear end of the sub-groove. Characterized in that it Kireaga' the side.

  In the drill configured as described above, among the chip discharge grooves formed only on the outer periphery of the cutting edge part, the main groove has a groove depth deeper than that of the auxiliary groove on the tip flank of the cutting edge part. A cutting blade having a length necessary for drilling can be formed at the intersecting ridge line portion of the surface facing the front side in the drill rotation direction and the tip flank. On the other hand, the groove depth of the main groove gradually becomes shallower toward the rear end side, and the main groove is cut to the outer peripheral side at the front end side than the rear end of the sub groove. On the end side, the drill body can be prevented from being greatly cut out on the radially inner peripheral side.

  On the other hand, the secondary groove is connected to the front side of the main groove in the direction of drill rotation, and extends from the tip flank face of the blade edge part toward the rear end side, beyond the raised part of the main groove, to the rear end side. Therefore, the effective cutting edge length L of the cutting edge is determined by the position of the rear end of the sub-groove. And even if there is no main groove on the rear end side of the cutting edge part beyond the cut-off portion of the main groove in this way, a certain groove depth is secured in the chip discharge groove by this sub groove, and the chip discharge property is maintained. In addition, the core thickness of the drill body can be made constant, and the core thickness is not greatly cut out on the radially inner peripheral side on the rear end side of the cutting edge as described above. For this reason, a large core thickness can be obtained, which makes it possible to give high strength and rigidity to the cutting edge portion.

  Here, in order to form such a chip discharge groove, the sub-groove is formed so as to extend with a constant groove width from the tip flank face toward the rear end side of the blade edge portion, and a drill for the sub-groove is formed. By forming the main groove so as to extend in parallel with the sub-groove from the tip flank so that the portion on the drill rotation direction front side of the main groove overlaps the portion on the rear side in the rotation direction, the tip of the cutting edge portion On the flank side, it is possible to secure a large groove width in the chip discharge groove excluding the overlapping part from the sum of the groove width of the main groove and the auxiliary groove, while the main groove can However, since the groove width of the overlapping sub-grooves is increased to the above-described constant groove width, it is possible to ensure the chip discharge property more reliably. Of course, when the actual chip discharge groove is formed, after forming the main groove, the sub-groove may be formed in parallel so as to overlap the drill rotation direction side.

  The length of the main groove in the axial direction is preferably in the range of 40 to 90% of the length of the sub-groove, and if the main groove is longer than this, the drill body on the rear end side of the cutting edge portion. On the other hand, if it is shorter than this, the depth of the main groove becomes shallower as it goes to the rear end side, which may impair chip discharge. Further, on the tip side of the cutting edge until the main groove is cut off, the sub-groove is formed in the range of 100 to 200 ° from the center of the groove width of the main groove toward the front side in the drill rotation direction around the axis. If the area where the sub-groove is formed is larger than this, the entire width of the chip discharge groove becomes too large, and the strength and rigidity of the drill body may be impaired on the tip side of the cutting edge. On the contrary, if the range in which the sub-groove is formed is smaller than this, the cross-sectional area of the chip discharge groove is also reduced, and there is a possibility that the chip discharge performance cannot be maintained.

  As described above, according to the present invention, it is possible to improve the strength and rigidity of the drill body on the rear end side of the blade edge part while maintaining good chip dischargeability, for example, a thick copper foil Even when a small hole with a small diameter is drilled on a printed circuit board, it is possible to prevent clogging and prevent breakage and the like.

It is a side view of the blade edge | tip part of the drill main body which shows one Embodiment of this invention. It is the sectional side view which showed typically the blade edge | tip part shown in FIG. It is XX expanded sectional drawing in FIG. It is YY expanded sectional drawing in FIG. It is ZZ expanded sectional drawing in FIG.

  1 to 5 show an embodiment of the drill of the present invention. In this embodiment, the drill body 1 is formed in a substantially multi-stage cylindrical shape centering on the axis O with a hard material such as cemented carbide, and a rear end side (right side in FIGS. 1 and 2) not shown is a shank portion. In addition, on the tip side of the shank portion (on the left side in FIGS. 1 and 2), a cutting edge portion 2 having a substantially long cylindrical shape having a smaller diameter than the shank portion is coaxially and integrally formed through a taper portion 3. Is formed.

  In such a drill, the shank portion is attached to the main shaft of the machine tool, and is rotated around the axis O in the drill rotation direction T and sent to the front end side in the axis O direction. Small holes and deep holes are drilled in work materials such as fine metal parts and plastics. Since the small-diameter deep hole is formed in this way, the drill of this embodiment has, for example, a maximum outer diameter D of the cutting edge portion 2 described below of about 0.05 to 0.5 mm and an effective cutting edge length of the cutting edge portion 2 ( The groove length L), which will be described later, is about 1.4 to 7.0 mm, and has an extremely fine blade edge portion 2 in which L / D is in the range of 5 or more.

  Only one chip discharge groove 4 is formed on the outer periphery of the blade edge portion 2. This chip discharge groove 4 opens at the tip flank 5 of the tip of the cutting edge 2, that is, the tip of the drill body 1, and extends while twisting to the rear side in the drill rotation direction T around the axis O toward the rear end side. The cutting edge 6 is formed so as to reach the front end side slightly of the taper portion 3, and the cutting edge 6 is formed at the intersecting ridge line portion between the surface of the chip discharge groove 4 facing the front side of the drill rotation direction T and the front end relief surface 5. Is formed. Therefore, the drill of this embodiment is a single-blade drill in which only one cutting blade 6 is formed. The diameter of the circle formed by the outer peripheral end of the cutting blade 6 around the axis O is the maximum of the cutting edge portion 2. The outer diameter is D.

  3 and 4, the chip discharge groove 4 is formed so as to be continuous with the main groove 7 located on the rear side in the drill rotation direction T and on the front side in the drill rotation direction T of the main groove 7. And a secondary groove 8. Among these, the minor groove 8 has a groove depth (the virtual cylinder described above) with respect to the maximum outer diameter D of the cutting edge portion 2, that is, with respect to a virtual cylindrical surface having a diameter of the maximum outer diameter D around the axis O. (Groove depth from the surface) is made constant, for example, within a range of 10 to 40% of the maximum outer diameter D, and from the tip flank 5 slightly toward the tip side of the tapered portion 3 as described above. It extends so as to reach the outer peripheral surface (second surface) of the blade edge 2 at its rear end.

  On the other hand, in the main groove 7, the groove depth with respect to the maximum outer diameter D (groove depth from the virtual cylindrical surface) is deeper than the sub-groove 8 at the portion opened to the tip flank 5. The groove depth gradually decreases toward the rear end side, and is formed so as to be cut off to the outer peripheral side at the tip end side of the blade edge portion 2 rather than the rear end of the sub-groove 8 slightly at the tip end side of the taper portion 3. Yes. Therefore, the cutting edge 6 is formed at the intersection ridge line portion between the surface facing the front side of the drill rotation direction T and the tip flank 5 of the bottom surface 7A of the main groove 7 located on the rear side of the drill rotation direction T. It will be.

  Here, in the present embodiment, the main groove 7 is formed so that the entire bottom surface 7A forms a concave arc shape in a cross section perpendicular to the axis O as shown in FIGS. It is symmetrical with respect to a straight line C connecting the center of the arc and the axis O of the drill body 1, and this straight line C is the center of the groove width of the main groove 7. The main groove 7 has a constant radius as the radius of the concave arc formed by the cross section of the bottom surface is the same as the distance from the axis O of the center of the main groove 7 from the tip flank 5 toward the rear end side of the cutting edge 2. The groove depth is gradually reduced by being formed so as to decrease in proportion, and accordingly, the groove width gradually decreases with the straight line C as the center as it goes to the rear end side. .

  On the other hand, the sub-groove 8 has a convex arc shape centered on the axis O as shown in FIGS. 3 to 5 in a cross section in which the bottom surface 8A is orthogonal to the axis O, as opposed to the main groove 7 in this embodiment. Since the groove depth is constant, the bottom surface 8A of the secondary groove 8 is twice as long as the groove depth of the secondary groove 8 from the maximum outer diameter D over the entire length of the cutting edge portion 2. It will be located on a cylindrical surface having a diameter minus the thickness. In addition, the groove width of the sub-groove 8 gradually increases toward the rear end side as opposed to the groove width of the main groove 7 gradually decreasing until the position where the main groove 7 is cut off. A constant groove width is formed on the rear end side from the cut-out position.

  The chip discharge groove 4 composed of the main groove 7 and the sub-groove 8 has, for example, the constant groove depth and the sub-groove 8 having the constant groove width as described above on the outer periphery of the blade edge portion 2 with respect to the axis O Next, the main groove 7 whose groove depth gradually decreases to the rear side of the drill rotation direction T of the sub-groove 8, and the portion in front of the drill rotation direction T is the drill rotation direction T of the sub-groove 8. The straight line C, which extends in parallel with the sub-groove 8 from the front flank 5 so as to overlap with the rear side portion, that is, the center C of the groove width becomes the sub-groove 8 as the main groove 7 moves toward the rear end side. It can be obtained by forming it so as to be twisted with respect to the axis O along a trajectory of a twist angle equal to the twist angle. Of course, the sub-groove 8 may be formed after the main groove 7 is formed. If possible, the main groove 7 and the sub-groove 8 are simultaneously formed to obtain the chip discharge groove 4 having such a shape. You may do it.

  In the present embodiment, the straight line C which is the center of the groove width of the main groove 7 is forward of the drill rotation direction T of the main groove 7 in each cross section orthogonal to the axis O as shown in FIGS. A trajectory of twisting toward the rear end side with a twist angle equal to the twist angle of the sub-groove 8 so as to coincide with the wall surface 8B on the rear side in the drill rotation direction T of the sub-groove 8 overlapping the side portion. . Accordingly, the main groove 7 in the present embodiment has a groove depth shallower toward the rear end side of the cutting edge portion 2, and is a portion on the front side in the drill rotation direction T with respect to the straight line C overlapping the sub groove 8. Is first cut to the bottom surface 8A of the sub-groove 8, and then the portion of the straight line C on the rear side in the drill rotation direction T is cut to the outer peripheral surface of the cutting edge portion 2 on the rear end side.

  Similarly, in each cross section orthogonal to the axis O, the sub-groove 8 is centered with respect to the axis O from the straight line C, which is the center of the groove width of the main groove 7, toward the front side of the drill rotation direction T around the axis O. The angle α is formed to be in the range of 100 to 200 °, and in the present embodiment, the central angle α is 180 °. Here, since the straight line C coincides with the wall surface 8B on the rear side in the drill rotation direction T of the sub-groove 8 as described above, the sub-groove 8 in the present embodiment has this central angle α as shown in FIG. Is formed in the range of 180 ° around the axis O.

  Further, as shown in FIG. 2, in the direction of the axis O, the groove length L of the auxiliary groove 8 from the foremost end of the cutting edge portion 2 to the rear end where the auxiliary groove 8 cuts to the second surface, that is, the effective cutting of the cutting edge portion 2 is performed. Similarly, the groove length M of the main groove 7 from the leading edge of the blade edge 2 to the rear end where the main groove 7 cuts to the second surface is set to a range of 40 to 90% with respect to the blade length. As shown in FIG. 2, the drill of this embodiment is configured such that the outer diameter of the rear end portion is slightly smaller than the outer diameter of the tip portion of the blade edge portion 2 through the step portion 2A. It is an undercut type drill, and the main groove 7 is cut to the bottom surface 8A of the sub-groove 8 on the rear end side with respect to the stepped portion 2A, and further cut to the second face on the rear end side. Has been.

  In the drill constructed as described above, first, the chip discharge groove 4 formed in the cutting edge portion 2 is only one, so that the portion where the drill body 1 is notched by the chip discharge groove 4 is small, and the core thickness is reduced. It can be enlarged, and high strength and rigidity can be secured in the blade edge portion 2. Further, in the drill having the above-described configuration, the chip discharge groove 4 is composed of a main groove 7 and a sub groove 8, and the sub groove 8 has a constant groove depth with respect to the maximum outer diameter D of the cutting edge portion 2. On the other hand, the main groove 7 is deeper at the front end flank 5 than the sub-groove 8, but gradually becomes shallower toward the rear end side and is cut off at the front end side than the rear end of the sub-groove 8. On the rear end side, the portion where the drill body 1 is notched to the radially inner peripheral side can be further reduced, and the core thickness can be further increased to improve the strength and rigidity.

  On the other hand, since the main groove 7 has the largest groove depth on the tip flank 5, drilling is performed on the cross ridge line portion between the surface facing the front side of the drill rotation direction T and the tip flank 5 of the bottom surface 7 </ b> A. Therefore, it is possible to reliably form the cutting blade 6 having a length necessary for the above. The chips generated by the cutting blade 6 are sent out from the main groove 7 having a large groove depth to the rear end side where the groove depth gradually decreases. The sub-grooves 8 are connected to each other, and the cross-sectional area of the chip discharge groove 4 can be sufficiently secured, so that good chip discharge performance can be maintained.

  Therefore, according to the drill having the above-described configuration, the strength and rigidity of the drill main body 1 on the rear end side of the blade edge portion 2 can be improved while maintaining such excellent chip dischargeability. The above ratio L / D of the blade edge portion 2 is large when a hole portion of a small diameter deep hole is formed in a printed circuit board on which a thick copper foil is pasted even in the drilling process to such a printed circuit board. However, it is possible to prevent the clogging of the copper foil due to the chips and increase the resistance or breakage of the cutting edge portion 2, thereby enabling stable and efficient drilling.

  In particular, in the drill of the present embodiment, the chip discharge groove 4 forms a sub-groove 8 having a constant width from the tip flank 5 toward the rear end side of the blade edge portion 2, and then the drill rotation direction of the sub-groove 8. Since the main groove 7 is formed in parallel with the sub-groove 8 so that the portion on the rear side in the drill rotation direction T of the main groove 7 overlaps the portion on the rear side of the T, the main groove 7 By overlapping the sub-groove 8, the groove width of the sub-groove 8 is conversely increased at the portion where the groove depth of the main groove 7 becomes shallow and cuts. For this reason, even in the portion where the main groove 7 is cut off, it is possible to prevent the chip discharging performance from being significantly impaired and to cause chip clogging, and to promote more smooth and stable drilling.

  In the present embodiment, the groove length M of the main groove 7 in the axis O direction is in the range of 40 to 90% of the groove length L of the sub-groove 8, that is, the groove length of the chip discharge groove 4. This also makes it possible to improve the strength and rigidity of the blade edge portion 2 while ensuring the chip discharge performance. That is, if the ratio of the groove length M of the main groove 7 is larger than this range, the main groove 7 extends to the rear end side, the drill body 1 is cut away, and the strength of the cutting edge portion 2 is increased. If the rigidity is less than the above range, the groove depth of the main groove 7 is abruptly decreased toward the rear end side. Even if is formed, there is a possibility that the chip discharging property is impaired.

  Further, in the present embodiment, on the tip side of the cutting edge portion 2 where the main groove 7 exists, the sub-groove 8 is a drill from the straight line C that is the center of the groove width of the main groove 7 in the cross section orthogonal to the axis O. The central angle α with the axis O as the center is formed in the range of 100 to 200 ° toward the front side in the rotation direction T, and this also improves the chip discharge performance and the strength and rigidity of the blade edge 2. It is possible to ensure both. That is, if the sub-groove 8 is formed so large that the central angle α exceeds the above range, the drill body 1 is largely cut off at the tip side of the cutting edge portion 2 together with the main groove 7, There is a possibility that the strength and rigidity necessary for cutting the cutting material cannot be ensured. On the contrary, if the range in which the auxiliary groove 8 is formed is smaller than the above range, good chip dischargeability can be obtained. There is a risk that it will not be possible.

  Furthermore, in the present embodiment, the bottom surface 8A of the sub-groove 8 has a convex curved surface curved in the circumferential direction of the drill body so as to form a convex arc centered on the axis O in a cross section orthogonal to the axis O. As a result, a larger core thickness can be ensured particularly on the rear end side of the blade edge portion 2 where the main groove 7 is cut off, and this can also contribute to improvement in strength and rigidity. On the other hand, the main groove 7 has a concave curved surface in which the bottom surface 7A forms a concave arc that is recessed toward the axis O in the cross section orthogonal to the axis O, for example, the bottom surface 8A of the sub-groove 8 In this way, a larger groove depth can be ensured if the cross-sectional area is the same as in the case of a convex curved surface shape, so that it is possible to improve the chip dischargeability.

  In addition, although this embodiment demonstrated the case where this invention was applied to the undercut type drill in which the outer diameter of the blade edge | tip part 2 becomes smaller one step | paragraph through the level | step-difference part 2A toward the rear end side, this blade edge | tip part 2 was demonstrated. The present invention can be applied to a back taper type drill whose outer diameter gradually decreases toward the rear end side, and can also be applied to a straight type drill in which the outer diameter of the blade edge portion 2 is constant. In any of these types, the sub-groove 8 only needs to have a constant groove depth with respect to the maximum outer diameter D of the cutting edge 6 of the cutting edge portion 2.

DESCRIPTION OF SYMBOLS 1 Drill main body 2 Cutting edge part 4 Chip discharge groove 5 Tip flank 6 Cutting edge 7 Main groove 8 Secondary groove O Axis line of drill main body T Drill rotation direction D Maximum outer diameter of cutting edge part 2 (diameter of cutting edge 6)
L Groove length of the auxiliary groove 8 in the axis O direction (the groove length of the chip discharge groove 4 and the effective cutting edge length of the cutting edge 2)
M Groove length of the main groove 7 in the direction of the axis O C A sub-groove 8 is formed from the straight line α which is the center of the groove width of the main groove 7 in the cross section perpendicular to the axis O toward the front side of the drill rotation direction T. Center angle around the axis O

Claims (4)

  On the outer periphery of the cutting edge portion on the tip end side of the drill body rotated about the axis, a single chip discharge groove consisting of a main groove and a secondary groove connected to the front side in the drill rotation direction of the main groove is the cutting edge portion of the cutting edge portion. The cutting edge is formed so as to extend from the front end toward the rear end side, and the cutting edge is formed on the intersecting ridge line portion between the wall surface facing the front side in the drill rotation direction of the main groove and the front end flank of the cutting edge portion. The sub-groove has a constant groove depth from the tip clearance surface toward the rear end side of the blade edge portion with respect to the maximum outer diameter of the blade edge portion formed by the cutting blade. The main groove has a groove depth deeper than the groove depth of the sub-groove on the tip flank, and the groove depth gradually becomes shallower toward the rear end side of the blade edge portion. A drill characterized by being cut off at the front end side of the rear end.   The chip discharge groove is formed on a portion on the rear side in the drill rotation direction of the sub-groove that extends with a constant groove width from the tip flank to the rear end side of the cutting edge. The drill according to claim 1, wherein the drill is formed so as to extend in parallel with the sub-groove from the tip flank by overlapping portions on the front side in the rotation direction.   The length of the said main groove in the said axial direction is made into the range of 40 to 90% of the length of the said subgroove, The drill of Claim 1 or Claim 2 characterized by the above-mentioned.   The sub-groove is formed within a range of 100 to 200 ° from the center of the groove width of the main groove toward the front side in the drill rotation direction around the axis line on the tip side of the cutting edge portion. The drill according to any one of claims 1 to 3.

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