JP2016112663A - End mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a chip discharging property, without impairing bottom blade hardness.SOLUTION: At a tip end portion of an end mill body 1, a gash 6, which is equipped with a first gash portion 10 extending from a tip end of a chip discharging groove to an inner peripheral side, and a second gash portion 11 extending from the first gash portion 10 to the further inner peripheral side, is formed. A bottom blade is formed at least at a tip end side ridge portion of a wall surface 11A turned in an end mill rotating direction T of the second gash portion 11, and a wall surface 10A turned in an end mill rotating direction T of the first gash portion 10 extends to the opposite side to the end mill rotating direction T toward an outer peripheral side, with respect to the wall surface 11A.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an end mill in which an outer peripheral blade is formed on the outer periphery of a tip end portion of an end mill body that is rotated around an axis, and a bottom blade is formed on a tip end portion of the end mill body.

  As such an end mill, for example, in Patent Document 1, in an end mill capable of feeding the end mill main body to the axial front end side and performing vertical feed processing such as digging of a workpiece, the inner periphery of the end mill main body from the tip of the chip discharge groove is disclosed. The gash notch angle that forms the wall facing the rear side in the end mill rotation direction (opposite to the end mill rotation direction) of the gasche extending toward the side with respect to the plane perpendicular to the axis of the end mill body is toward the rear end side of the end mill body A plurality of steps that increase stepwise as the gash rake angle formed with respect to the axis line increases toward the rear end side. It has been proposed that it is composed of a gash rake face.

  According to such an end mill, while ensuring the strength at the center of the end of the end mill body where a large load is applied during vertical feed machining, the chip separation is improved by a multi-stage gash face and a gash rake face. Chip discharge property can be obtained. Of course, both of a plurality of stages of gash surfaces and a plurality of stages of gash rake faces may be provided.

JP 2006-015418 A

  By the way, instead of such vertical feed processing, when a normal end mill body is sent in a direction perpendicular to the axis line to perform groove cutting processing, or when it is sent to an oblique tip side with respect to the axis line to perform ramping processing, In the case of the tip of the outer peripheral blade or the radius end mill, the chips generated by the corner blade try to flow into the inner peripheral side of the end mill body through the gasche. On the other hand, since the chips generated by the bottom blade flow into the chip discharge groove from the gash, clogging easily occurs due to interference of these chips on the outer peripheral side of the end mill main body of the gash.

  In particular, in a multi-blade end mill having four or more bottom blades formed on the end mill body, it is difficult to form all the bottom blades to the center of the end portion of the end mill body. The bottom blade must be a short bottom blade extending from a position away from the center of the tip, but with such a short bottom blade, the gasche also extends from a position away from the center of the tip of the end mill body.

  Therefore, if the angle between the wall surface facing the end mill rotation direction of the gash of the short bottom blade and the wall surface facing the opposite side is constant, the width of the gash becomes smaller on the outer peripheral side of the end mill body, and further chip clogging occurs. Is likely to occur. On the other hand, when the width and the included angle of the gasche are increased, the thickness on the inner peripheral side of the end mill body on the side opposite to the end mill rotation direction of the bottom blade is reduced, and the bottom blade strength is reduced to cause a defect or the like. There is a fear.

  The present invention has been made under such a background, and even in a multi-blade end mill, an end mill capable of improving chip discharge performance without impairing the strength of the bottom blade on the inner peripheral side of the end mill body. The purpose is to provide.

  In order to solve the above problems and achieve such an object, according to the present invention, a chip discharge groove extending from the front end of the end mill main body to the rear end is provided on the outer periphery of the front end of the end mill main body rotated about the axis. An outer peripheral blade is formed on the outer peripheral side ridge portion of the wall surface facing the end mill rotation direction of the chip discharge groove, and the end mill body has a tip portion of the end mill body from the tip of the chip discharge groove. A gash comprising a first gash part extending toward the inner peripheral side, and a second gash part extending further from the first gash part to the inner peripheral side of the end mill body is formed, of which at least the first gash part is formed. A bottom blade is formed at the tip side edge of the wall surface facing the end mill rotation direction of the second gash portion, and the wall surface facing the end mill rotation direction of the first gash portion is Against the wall surface facing the end mill rotating direction of the second gash section, the end mill rotating direction toward the outer peripheral side of the end mill body, characterized in that it extends toward the opposite side.

  In such an end mill, a wall surface facing the end mill rotation direction of the first gash portion extending from the tip of the chip discharge groove on the outer peripheral side of the tip end of the end mill body to the inner peripheral side of the gash is further from the first gash portion. The wall surface facing the end mill rotation direction of the second gash portion extending toward the inner peripheral side extends toward the opposite side of the end mill rotation direction toward the outer peripheral side of the end mill body, so that groove cutting or ramping is performed. It is possible to suppress the chips generated by the tip of the outer peripheral blade and the corner blade during processing from flowing into the inner peripheral side of the end mill body.

  Further, in addition to this, the outer peripheral side of the end mill body with respect to the wall surface facing the direction opposite to the end mill rotation direction of the second gash portion with respect to the wall surface facing the direction opposite to the end mill rotation direction of the second gash portion. The width in the circumferential direction of the first gash part can be made larger than the case where the second gash part is directly extended to the outer periphery side of the end mill body by forming it so as to extend in the end mill rotation direction as it goes toward it can. For this reason, even if the chips generated by the bottom blade flow to the outer peripheral side, it is possible to avoid interference with the chips generated by the tip of the outer peripheral blade or the corner blade. On the other hand, since it is not necessary to enlarge the second gash part on the inner peripheral side, the strength of the bottom blade can be ensured.

  Therefore, according to such an end mill, the end mill body is a multi-blade end mill in which four or more bottom blades are formed at intervals in the circumferential direction at the tip portion of the end mill body. Even if it extends from a position away from the center of the part, it is possible to perform stable cutting while preventing the bottom blade from being damaged. Further, by forming the wall surface of the second gash portion facing the end mill rotating direction so as to extend toward the side opposite to the end mill rotating direction toward the outer peripheral side of the end mill body, It is possible to more reliably prevent the chips generated by the blade from flowing into the second gash portion on the inner peripheral side of the end mill body.

  As described above, according to the present invention, it is possible to prevent chip clogging by improving chip discharging performance while preventing chipping due to insufficient strength of the bottom blade, and stable cutting can be performed. It becomes.

It is a perspective view which shows one Embodiment of this invention. It is a side view of embodiment shown in FIG. It is an enlarged front view of embodiment shown in FIG. FIG. 3 is a ZZ enlarged sectional view in FIG. 2.

  1 to 4 show an embodiment of the present invention. In the present embodiment, the end mill main body 1 is formed in a substantially cylindrical shape centering on the axis O by a hard material such as cemented carbide, and the rear end portion (the upper right portion in FIG. 1 and the upper portion in FIG. 2) is a circle. The shank portion 2 remains in a columnar shape, and the tip portion (lower left portion in FIG. 1, lower portion in FIG. 2) is a cutting edge portion 3.

  In such an end mill, the shank portion 2 is gripped by the spindle of the machine tool and rotated in the end mill rotation direction T around the axis O, and is usually fed in a direction perpendicular to the axis O to perform groove cutting. Or is sent to the tip side obliquely with respect to the axis O and used for ramping. In some cases, as described in Patent Document 1, it is sent along the axis O to the tip side to perform longitudinal feed processing.

  On the outer periphery of the cutting edge portion 3, a plurality of (six in this embodiment) chip discharge grooves twisted in the direction opposite to the end mill rotation direction T around the axis O from the front end to the rear end side of the end mill body 1. 4 are formed at equal intervals in the circumferential direction, and outer peripheral blades 5 having a rake face as the wall surface are respectively formed on the outer peripheral side ridges of the wall surfaces of the chip discharge grooves 4 facing the end mill rotation direction T. ing. These outer peripheral blades 5 are arranged so that the rotation locus around the axis O forms one cylindrical surface with the axis O as the center.

  Further, a groove-like gash 6 extending from the tip of each chip discharge groove 4 toward the inner peripheral side is formed at the tip of the end mill body 1. As shown in FIG. 2, these gashes 6 have a V-shape that becomes narrower in the circumferential direction toward the rear end side of the end mill body 1 as shown in FIG. Even when viewed from the front in the direction of the axis O, the opening is formed in a V-shape that becomes narrower in the circumferential direction toward the inner peripheral side of the end mill body 1. Further, the gasche 6 is formed such that the groove depth toward the rear end side in the axis O direction gradually becomes shallower toward the inner peripheral side of the end mill body 1.

  Furthermore, as shown in FIG. 2, some of the gashes 6A of these gashes 6 extend longer toward the inner peripheral side of the end mill body 1, while the remaining gashes 6B are more than the gashes 6A. The end mill body 1 is formed so as to extend to the inner peripheral side. In the present embodiment, two partial gashes 6A extending in the left and right directions in FIG. 2 extend in the inner peripheral side so as to cross each other beyond the axis O, and the remaining four gashes 6B are formed along the axis O. The inner periphery of the gash 6A communicates with the inner periphery of the part of the gash 6A. In the end mill of this embodiment, the end mill body 1 is formed in a 180 ° rotationally symmetric shape with respect to the axis O.

  Further, a portion between the gasches 6 adjacent in the circumferential direction on the tip surface of the end mill body 1 is a tip flank 7. The tip flank 7 of the present embodiment is composed of first and second tip flank surfaces 7A and 7B whose flank angle increases stepwise toward the opposite side of the end mill rotation direction T. Furthermore, a bottom edge 8 having a rake face as a wall surface is formed on each edge ridge portion of the wall surface facing the end mill rotation direction T of each gash 6 that is an intersecting ridge line with the tip flank 7. Yes. In the present embodiment, these bottom blades 8 are formed at equal intervals in the circumferential direction, and are linearly located on one plane perpendicular to the axis O, or provided with a watermark angle, so that the end mill body 1 has a straight angle. As it goes to the inner peripheral side, it forms a straight line slightly inclined toward the rear end side in the direction of the axis O.

  Here, as described above, some of the gashes 6A extend to the inner peripheral side of the end mill main body 1 and the remaining gashes 6B are formed to extend shortly. The two partial bottom blades 8 formed on the wall surface facing T are long bottom blades 8A extending longer than the remaining bottom blades 8 formed on the wall surface facing the end mill rotation direction T of the remaining gash 6B, In this embodiment, as shown in FIG. 2, they are formed so as to cross each other over the axis O. The remaining four bottom blades 8 other than these long bottom blades 8A are short bottom blades 8B.

  However, these long bottom blades 8A and some of the above-mentioned gashes 6A do not cross each other, and there is a tip flank 7 (first tip) connected to these long bottom blades 8A between the long bottom blades 8A. When the flank surfaces 7A) intersect with each other, a short intersecting ridge line portion 9 orthogonal to the axis O is formed. Further, the short bottom blade 8B has an axis O that is longer than the long bottom blade 8A when the inner peripheral portion of the remaining gash 6B in which the short bottom blade 8B is formed communicates with the inner peripheral portion of the partial gash 6A. It has an inner peripheral edge at a distant position.

  The gash 6 includes a first gash part 10 in which a part of the gash 6A and the remaining gash 6B extend from the tip of the chip discharge groove 4 toward the inner peripheral side of the end mill body 1, and the first gash 6 The second gash part 11 extends further from the gash part 10 to the inner peripheral side of the end mill body 1. Further, the bottom blade 8 is formed on the tip side ridge portion of the wall surface 11 </ b> A in which both the long bottom blade 8 </ b> A and the short bottom blade 8 </ b> B face the end mill rotation direction T of the second gash portion 11 of each gash 6. Yes.

  Here, in this embodiment, at the corner portion where each bottom blade 8 and the outer peripheral blade 5 intersect, at the tip outer peripheral side ridge portion of the wall surface 10A facing the end mill rotation direction T of the first gash portion 10, A corner blade 12 having a convex curve shape such as a quarter arc connected to the bottom blade 8 and the outer peripheral blade 5 is formed. That is, the end mill of this embodiment is a radius end mill, and the wall surface 10 </ b> A facing the end mill rotation direction T of the first gash portion 10 is a rake face of the corner blade 12.

  Furthermore, the wall surface 10A facing the end mill rotation direction T of the first gash part 10 is the outer periphery of the end mill body 1 with respect to the wall surface 11A facing the end mill rotation direction T of the second gash part 11 as shown in FIG. It extends so that it may go to the opposite side to the end mill rotation direction T as it goes to the side. On the other hand, the wall surface 10B facing the direction opposite to the end mill rotation direction T of the first gash part 10 is also changed to the wall surface 11B facing the side opposite to the end mill rotation direction T of the second gash part 11 as shown in FIG. In contrast, the end mill body 1 extends in the end mill rotation direction T toward the outer peripheral side of the end mill body 1.

  The wall surfaces 10A and 11A facing the end mill rotation direction T of the first and second gash portions 10 and 11 and the wall surfaces 10B and 11B facing the opposite side of the end mill rotation direction T are formed in a planar shape. The wall surfaces 10A and 11A and the wall surfaces 10B and 11B extend in directions that intersect each other at an obtuse angle. However, the bottom of the valley where the wall surfaces 10A, 10B, 11A, and 11B intersect in the first and second gash portions 10 and 11 is formed in a concave curved surface that is continuous with these planes.

  Further, the virtual ridge line (valley line) formed by the extended surfaces of the wall surfaces 10A and 10B and the wall surfaces 11A and 11B that are planar as described above is more than the virtual ridge line of the wall surfaces 10A and 10B of the first gash portion 10. In addition, the virtual ridgeline between the wall surfaces 11A and 11B of the second gash portion 11 is configured so that the inclination with respect to the axis O becomes gentle. However, these virtual ridge lines are not continuous, and as shown in FIG. 1, the virtual ridge lines between the wall surfaces 10A and 10B of the first gash portion 10 rather than the virtual ridge lines between the wall surfaces 11A and 11B of the second gash portion 11. Is located on the outer peripheral side of the end mill body 1.

  Further, in the first gash portions 10 of the respective gash 6, the included angles formed by the wall surface 10 </ b> A and the wall surface 10 </ b> B around the virtual ridge line are equal to each other. Similarly, also in the second gash portions 11 of each gash 6, the angle between the wall surface 11A and the wall surface 11B about the virtual ridge line is equal to each other, and the wall surface of the first gash portion 10 is also the same. It is made smaller than the included angle formed by 10A and 10B. Further, in the present embodiment, the wall surface 11A facing the end mill rotation direction T of the second gash portion 11 is slightly opposite to the end mill rotation direction T as it goes to the outer peripheral side of the end mill body 1 as shown in FIG. Thus, the bottom blade 8 and the corner blade 12 are given a negative radial rake angle.

  Note that in all the gash 6 including a part of the gash 6A and the remaining gash 6B, as shown in FIG. 4, in the cross section orthogonal to the axis O as shown in FIG. 4, the contact P1 between the circle C1 inscribed in the first gash part 10 of the part of the gash 6A and the first gash part 10 is the second gash part 11 (in FIG. It is located on the opposite side of the end mill rotation direction T from the contact point P2 between the circle C2 inscribed in the second gash part 11) of the gash 6A and the second gash part 11.

  In the end mill (radius end mill) configured as described above, when the above-described grooving or ramping is performed, the chips generated by the corner blade 12 first flow into the first gash portion 10 on the outer peripheral side of the end mill body 1. The wall surface 10A facing the end mill rotation direction T of the first gash portion 10 which is the rake face of the corner blade 12 is relative to the wall surface 11A facing the end mill rotation direction T of the second gash portion 11 on the inner peripheral side. Since it extends toward the opposite side to the end mill rotation direction T as it goes toward the outer peripheral side, it is possible to suppress trying to enter the second gash part 11 by pushing out the chips that flow into the outer peripheral side. .

  Furthermore, in addition to the wall surface 10 </ b> A extending toward the opposite side to the end mill rotation direction T toward the outer peripheral side with respect to the wall surface 11 </ b> A, the side opposite to the end mill rotation direction T of the first gash portion 10. The wall surface 10 </ b> B facing the side extends toward the end mill rotation direction T toward the outer peripheral side of the end mill body 1 with respect to the wall surface 11 </ b> B facing the side opposite to the end mill rotation direction T of the second gash part 11. Therefore, the width of the first gash part 10 or the included angle formed by the wall surfaces 10A, 10B of the first gash part 10 around the virtual ridge line is extended to the outer peripheral side of the second gash part 11 as it is. It can be made larger.

  In particular, in the present embodiment, some of the plurality of gashes 6 are extended to the inner peripheral side of the end mill body 1 while the remaining gash 6B is within the end mill body 1 more than some of the gashes 6A. When the remaining gash 6B extends shortly to the peripheral side and the wall surfaces 11A and 11B of the second gash part 11 on the inner peripheral side extend to the outer peripheral side with the same sandwich angle, the outer periphery of the end mill body 1 The width of the gash 6B on the side becomes too smaller than a part of the gash 6A, and chip clogging is more likely to occur.

  On the other hand, in order to prevent the width of the gash 6B on the outer peripheral side from being reduced in this way, the sandwiching angle of the remaining gash 6B is made larger from the inner peripheral side to the outer peripheral side than a part of the gash 6A. In particular, in a multi-blade end mill having six bottom blades 8 as in the present embodiment, the remaining gash 6B having a larger included angle on the inner peripheral side of the end mill body 1 and the gash 6 adjacent to the end mill rotation direction T side. The thickness of the end mill main body 1 is reduced, and the strength of the bottom blade 8 with the wall surface 11A facing the end mill rotation direction T of the gasche 6 adjacent to the end mill rotation direction T side as a rake face is impaired, resulting in defects. May occur.

  On the other hand, according to the end mill having the above-described configuration, it is possible to ensure the capacity by increasing the included angle of the first gash portion 10 as described above without increasing the included angle of the second gash portion 11. Can do. For this reason, even if it is a multi-blade end mill in which four or more, especially six or more bottom blades 8 are formed at intervals in the circumferential direction as in this embodiment, the strength of the bottom blade 8 is not impaired. Chips generated by the bottom blade 8 and flowing from the second gash part 11 to the first gash part 10 can be prevented from interfering with the chips generated by the corner blade 12, and the occurrence of chip clogging is prevented. Thus, it is possible to obtain a good chip discharge property and perform stable cutting such as grooving or ramping.

  Further, since the wall surface 10A of the first gash part 10 extends to the side opposite to the end mill rotation direction T with respect to the wall surface 11A of the second gash part 11, the chips generated by the bottom blade 8 are the first. The chip separation when flowing into the gash portion 10 can be improved, and the chip discharge performance can be improved also by this. In FIG. 4, the valley bottom portion forming the concave curved surface shape of the first gash portion 10 intersects the wall surface 11 </ b> A facing the end mill rotation direction T of the second gash portion 11, and the concave portion has a concave curved surface. However, the planar wall surface 10A of the first gash part 10 may intersect the wall surface 11A as it is.

  Further, in the present embodiment, negative radial rake angles are given to the bottom blade 8 and the corner blade 12, and the end mill as the wall surface 11 </ b> A and the wall surface 10 </ b> A themselves that are rake faces move toward the outer peripheral side of the end mill body 1. Since it extends toward the opposite side to the rotational direction T, the inclination of the wall surface 10A, which is the rake face of the corner blade 12, toward the opposite side to the end mill rotational direction T can be further increased. It becomes possible to reliably suppress the inflow of chips into the second gash portion 11. In addition, the blade angle of the corner blade 12 can be increased to improve the cutting edge strength.

  In this embodiment, when the present invention is applied to a radius end mill in which a convex curved corner blade 12 is formed between the outer peripheral blade 5 and the bottom blade 8 on the outer peripheral end of the end mill body 1. However, the present invention can also be applied to a square end mill in which the outer peripheral edge 5 and the bottom edge 8 intersect with each other at an angle. In such a case, the wall surface 10 </ b> A facing the end mill rotation direction T of the first gash part 10 may intersect the tip part of the outer peripheral blade 5.

  In the present embodiment, the included angle in the first gash part 10 of each gash 6 is equal to the included angle in the second gash part 11, but at least one of these included angles is gasshed. The size may be different between the six. For example, with respect to the sandwiching angle of the first gash part 10 of the remaining gash 6B where the short bottom blade 8B is formed, the sandwiching of the first gash part 10 of the part of the gash 6A where the long bottom blade 8A is formed If the corners are widened to increase the width, the chip discharging performance of the long bottom blade 8A that generates more chips than the short bottom blade 8B can be further improved.

  Furthermore, with respect to the included angle of the second gash part 11 of the remaining gash 6B where the short bottom blade 8B is formed, the second gash part 11 of the part of the gash 6A where the long bottom blade 8A is formed is sandwiched. If the angle is reduced to make the width narrower, the wall thickness between the part of the gash 6A extending to the vicinity of the axis O on the inner peripheral side of the end mill main body 1 and the gash 6 adjacent to the end mill rotation direction T side becomes larger. It is possible to secure higher strength to the bottom blade 8 formed on the gasche 6 adjacent to the end mill rotation direction T side.

DESCRIPTION OF SYMBOLS 1 End mill main body 3 Cutting blade part 4 Chip discharge groove 5 Outer peripheral blade 6 Gash 7 Tip flank 8 Bottom blade 10 1st gash part 10A Wall surface 10B 1st gash part facing the end mill rotation direction T of the first gash part 10 10 is a wall surface facing away from the end mill rotation direction T 11 Second gash portion 11A A wall surface facing the end mill rotation direction T of the second gash portion 11B 11B is the opposite side of the end mill rotation direction T of the second gash portion 11 Wall facing 12 Corner edge O End mill body 1 axis T End mill rotation direction

Claims (4)

A chip discharge groove extending from the front end of the end mill main body to the rear end side is formed on the outer periphery of the end mill main body rotated about the axis, and the outer peripheral side edge of the wall facing the end mill rotation direction of the chip discharge groove. An outer peripheral blade is formed on the
The end portion of the end mill main body includes a first gash portion extending from the tip of the chip discharge groove toward the inner peripheral side of the end mill main body, and further from the first gash portion to the inner peripheral side of the end mill main body. A gash having a second gash part extending is formed, and a bottom blade is formed at a ridge part on the tip side of the wall surface facing the end mill rotation direction of at least the second gash part,
The wall surface facing the end mill rotation direction of the first gash part is directed to the side opposite to the end mill rotation direction toward the outer peripheral side of the end mill body with respect to the wall surface facing the end mill rotation direction of the second gash part. End mill characterized by extending like   The wall surface facing the direction opposite to the end mill rotation direction of the first gash portion is the end mill toward the outer peripheral side of the end mill body with respect to the wall surface facing the direction opposite to the end mill rotation direction of the second gash portion. The end mill according to claim 1, wherein the end mill extends in a rotational direction.   The end mill according to claim 1 or 2, wherein four or more bottom blades are formed at a distal end portion of the end mill main body at intervals in the circumferential direction.   The wall surface facing the end mill rotation direction of the second gash portion extends toward the opposite side of the end mill rotation direction toward the outer peripheral side of the end mill main body. The end mill as described in any one of these.

Images