JP6089917B2 - Unequal lead end mill - Google Patents

Description

  The present invention relates to an unequal lead end mill having different twist angles of outer peripheral cutting edges.

  2. Description of the Related Art Conventionally, an end mill having a plurality of outer peripheral cutting edges that are twisted around a rotation axis that is classified as a handle mill is known. In this type of end mill, in order to prevent chatter vibration during cutting, etc., an unequal twist end mill (or a twist angle of at least one of the cutting edges is different from the twist angle of the other cutting edges) (or , Non-equal lead end mill). Further, there is an unequal division end mill in which the circumferential pitches of adjacent cutting edges are different when viewed in a cross section perpendicular to the axis. In such an unequal lead end mill and an unequal division end mill, the shape and amount of the cutting waste cut by the outer peripheral cutting edge differ for each cutting edge.

  Therefore, for example, in Patent Document 1, since a large amount of chips are produced on the wide chip discharge groove side forming the rake face on the wide pitch side of the unequal division end mill, the bottom of the wide discharge groove is in contact with the center. The discharge groove cross-sectional area as viewed in the cross section perpendicular to the axis is increased by reducing the thickness. On the contrary, since the amount of the chip on the narrow side is small, the core thickness with which the bottom of the chip discharge groove on the narrow side is in contact is increased, the discharge groove cross-sectional area in the cross section perpendicular to the axis is reduced, and the end mill rotates. A large wall thickness is secured on the direction publication side to increase the strength. Similarly, in the case of an unequal lead end mill, the core thickness with which the bottom of the discharge groove on the side where the width is increased is reduced and the core thickness with which the bottom of the discharge groove on the side where the width is reduced is increased. In addition, the shape of the discharge groove cross section seen in the cross section perpendicular to the axis is a shape that facilitates discharge of chips so that the cross-sectional area becomes large.

  Further, in Patent Document 2, as viewed in a cross section perpendicular to the axis, the bottom surface of the chip discharge groove of the unequal lead end mill forms a straight line from the position where the bottom portion of the chip discharge groove contacts the core thickness circle, and the groove bottom surface extends in the end mill rotation direction. By making it into the shape which made the sub-groove bottom part which makes | forms the straight line extended further toward a rotation direction crossing an obtuse angle at the groove bottom face, the edge strength is ensured and the chip | tip discharge | emission is improved.

  On the other hand, in Patent Document 3, a back taper similar to the back taper of the outer diameter cutting edge of the end mill is given to the core thickness side, and the distance between the axial tool outer diameter and the core thickness is made substantially constant. Thereby, by setting the outer peripheral cutting edge to a predetermined rake angle, the cutting performance of the cutting edge is ensured and tool damage is prevented. On the contrary, in Patent Document 4, the thickness of the end mill is gradually increased from the tip toward the handle (shank) side, and the strength of the end mill is increased while ensuring chip discharge.

JP 2007-136627 A JP 2009-220188 A JP 2008-264964 A International Publication Number WO2013 / 005307 A1

  However, in the end mills of Patent Documents 1 and 2, the shape of the chip discharge groove in the axial section is enlarged or the discharge performance is improved, but the chip discharge performance in the axial direction is described. It has not been. Further, even in the case of unequal lead end mills, changes in the axial direction are not described. In Patent Document 3, the depth of the axial chip discharge groove is substantially constant. Moreover, in the thing of patent document 4, the discharge groove width etc. are enlarged as a countermeasure against the increase in the core thickness, and the chip discharge groove in which the chip discharge groove width is reduced is not mentioned. On the other hand, in the case of an unequal lead end mill, there is no problem even if the shape and depth of the chip discharge groove are the same as in the case of the chip discharge groove on the side where the chip discharge groove width is increased. However, in the case of the chip discharge groove on the side where the chip discharge groove width is reduced, the chip discharge groove cross-sectional area as viewed in the direction perpendicular to the axis is gradually reduced, so that there is a problem that chips are easily clogged.

  In view of the above-mentioned problems, the object of the present invention is to improve the chip discharge performance in the axial direction of the unequal lead end mill, particularly the chip discharge performance of the chip discharge groove on the side where the chip discharge groove width is reduced. There is to make it.

  In the present invention, it has a blade part composed of a tip cutting edge and an outer peripheral twist cutting edge, and a handle part that supports the blade part, and the adjacent outer cutting edges have different twist angles, and the outer peripheral cutting edge is different from each other. A width-side discharge groove in which the width of the chip discharge groove between the blades gradually increases from the tip toward the handle portion, and a width of the chip discharge groove between the outer peripheral cutting edges from the tip toward the handle portion. In the unequal lead end mill having a reduced width side discharge groove that gradually decreases, a groove bottom depth of the wide side discharge groove gradually decreases from the tip toward the handle portion raised portion, and the reduced width side discharge groove The above-mentioned problem has been solved by providing an unequal lead end mill in which the groove bottom depth of the groove gradually increases from the tip toward the handle portion raised portion.

  In other words, since the groove bottom depth of the reduced width side discharge groove of the unequal lead end mill is gradually increased from the tip toward the handle cut-up portion, even if the width of the chip discharge groove gradually decreases, the axial chip discharge The decrease in the cross-sectional area of the groove is made small, constant, or gradually increased. It is preferable that the groove bottom depth of the reduced width side discharge groove is such that the axial sectional area of the chip discharge groove is constant or gradually increased. On the other hand, since the groove bottom depth of the wide-side discharge groove is gradually decreased from the tip toward the handle part cut-up part, the cross-sectional area of the axial chip discharge groove is not increased unnecessarily, and the core thickness can be secured.

  Further, in the invention described in claim 2, the core thickness diameter at which the groove bottom of the reduced width side discharge groove contacts is larger than the core thickness diameter at which the groove bottom of the wide side discharge groove contacts at the tip. An equal lead end mill was used.

  Since the core thickness of the widening side discharge groove increases from the tip to the handle, the core thickness on the tip side is small. Further, since the core thickness of the reduced width side discharge groove decreases from the tip to the handle, the core thickness on the tip side is large. Therefore, the core thickness of the entire blade portion is averaged by making the core thickness diameter of the reduced width side discharge groove larger than the core thickness diameter of the wide side discharge groove on the tip side.

  Furthermore, in the invention described in claim 3, at the position where the outer peripheral cutting edge is equally divided in the cross section in the axial direction, the core thickness diameters with which the groove bottoms of the widening side and the narrowing side discharge groove are in contact are made the same. It was an unequal lead end mill. That is, the core thickness was made the same on the equally divided surface of the outer peripheral cutting edge.

  In the present invention, the groove bottom depth of the reduced width side discharge groove is gradually increased from the tip toward the handle portion uplift portion, and the reduction in the cross-sectional area of the chip discharge groove in the axial direction is reduced or constant or increased gradually. Therefore, the chip discharge property of the narrow side discharge groove of the unequal lead end mill is improved. On the other hand, since the depth of the bottom of the wide-side discharge groove is gradually reduced to ensure the conventional chip discharge and core thickness, the strength is not lowered.

  Further, in the invention according to claim 2, since the core thickness diameter of the reduced width side discharge groove is made larger than the core thickness diameter of the wide side discharge groove on the tip side, the core thickness of the entire blade portion is averaged. In addition, the same strength and toughness as the conventional core thickness are secured, and the chip discharge performance is also improved. Furthermore, in the invention according to claim 3, since the core thickness is the same on the equally divided surface of the outer peripheral cutting edge, it is easy to ensure the core thickness strength and discharge performance, or to design, manufacture or inspect easily. .

It is a side view of an unequal lead end mill showing an embodiment of the invention. (A) of the unequal lead end mill which shows embodiment of this invention is an axial direction cross-sectional explanatory drawing of the core thick part of a wide side chip discharge groove, (b) is a width side discharge groove. It is an AA line expanded sectional view of FIG. It is a BB line expanded sectional view of Drawing 1. FIG. 3 is an enlarged cross-sectional view taken along the line CC in FIG. 1.

  Embodiments of the present invention will be described with reference to the drawings. It should be noted that the drawings are for explanation, and the shape and the like are exaggerated. 3 to 5 show changes in the cross-sectional shape with one of the cutting edges 3 facing upward for the sake of explanation. As shown in FIG. 1, in the embodiment of the present invention, the present invention is applied to a four-blade square unequal lead end mill. A four-blade square unequal lead end mill (hereinafter referred to as “end mill”) 1 is provided with a tip cutting edge (bottom cutting edge) 2 at the tip, and an outer peripheral twist cutting edge in the axial direction around the axis from the outer periphery of the bottom cutting edge. 3 and 4 are formed, and the blade part 5 is formed. Furthermore, it has a handle 6 that supports the blade. In addition, about a front-end | tip part, since it is the same as that of the past, description is abbreviate | omitted.

  The outer peripheral twist cutting blades 3 and 4 are formed as a set of two pieces in axisymmetric position, and a total of four sets are formed. The twist angles α and β of the peripheral twist cutting edges 3 and 4 adjacent to each other (alternately disposed cutting edges) are different from each other. So-called unequal leads. Chip discharge grooves 7 and 8 are provided between adjacent outer peripheral cutting edges, and outer peripheral cutting edge rake surfaces 3a and 4a are formed. The twist angle α of the cutting edge 3 is smaller than the twist angle 4 of the cutting edge 4. Thereby, the wide side discharge groove 7 is formed between the flank (back surface) 3 b of the cutting edge 3 and the rake face 4 a of the cutting edge 4. The groove width 7w of the wide-side discharge groove 7 is gradually increased from the tip toward the handle 6. On the other hand, a narrow-side discharge groove 8 is formed between the flank (back surface) 4 b of the cutting edge 4 and the rake face 3 a of the cutting edge 3. The groove width 8w of the narrow-side discharge groove 8 gradually decreases from the tip toward the handle 6.

  As shown in FIG. 2A, the depth 7 d of the groove bottom 7 a of the wide side discharge groove 7 is gradually reduced from the tip toward the handle part raising portion 11. Further, as shown in FIG. 2 (b), the groove bottom 8 a depth 8 d of the reduced width side discharge groove 8 gradually increases from the tip toward the handle portion raised portion 12. Therefore, as shown in FIGS. 2 and 3, the core thickness 13a of the core thickness 13 with which the groove bottom 7a contacts as viewed in the cross section perpendicular to the axis of the wide side discharge groove 7 is the center with which the groove bottom 8a of the narrow side discharge groove 8 contacts. The thickness 14 is larger than the core thickness diameter 14a. Therefore, the pitch between the cutting edges is small between the flank face of the cutting edge 3 and the rake face of the cutting edge 4 (wide-side discharge groove), and the clearance between the flank face of the cutting edge 4 and the rake face of the cutting edge 3 is small. The interval (narrow width side discharge groove) 8 is largely divided unevenly.

  Then, in the middle of the blade portion 2, as shown in FIGS. 2 and 4, the core thickness diameter 13b of the wide side discharge groove 7 is made the same as the core thickness diameter 14b of the narrow side discharge groove 8. Therefore, the pitch between the cutting edges is between the flank face of the cutting edge 3 and the rake face of the cutting edge 4 (wide side discharge groove) 7, and between the flank face of the cutting edge 4 and the rake face of the cutting edge 3. (Narrow side discharge groove) 8 is the same and is divided equally.

  Further, in the vicinity of the rounded-up portion 11 of the blade portion 2, as shown in FIGS. 2 and 5, the core thickness diameter 13 c of the wide side discharge groove 7 is made larger than the core thickness diameter 14 c of the narrow width side discharge groove 8. Therefore, the pitch between the cutting edges is between the flank face of the cutting edge 4 and the rake face of the cutting edge 3 from the flank face of the cutting edge 3 and the rake face of the cutting edge 4 (wide side discharge groove) 7. (Narrow width side discharge groove) 8 is a small unequal division.

  The groove cross-sectional area of the chip groove in the axial cross section in the wide-side discharge groove 7 becomes shallower as the lateral width becomes wider. On the other hand, in the reduced width side discharge groove 7, the groove depth becomes deeper as the lateral width becomes narrower. Thereby, the change of the cross-sectional area of the chip discharge groove can be reduced or made constant, and chip discharge becomes easy. In particular, the narrow width side discharge groove has a problem that the groove width becomes narrow on the handle portion side, so that there has been a problem that the chip is likely to be clogged in the past. Sexually improves. Further, since the core thickness diameter on the wide side discharge groove side is increased from the small diameter to the large diameter toward the handle portion, the core thickness on the handle portion side where the cutting amount increases becomes thick and the strength can be secured. On the other hand, the core thickness diameter of the reduced width side discharge groove is changed from a large diameter to a small diameter toward the handle portion. However, since the cutting amount is smaller on the handle portion side, the strength is not insufficient. Thus, the core thickness strength can be sufficiently secured.

  Moreover, although the front-end | tip part was made into unequal division and the intermediate part was made into equal division, it is good also considering one side of a front-end | tip part or a handle part side as equal division. In the embodiment of the present invention, the square end mill has been described, but it goes without saying that the present invention can be applied to an unequal lead end mill having an outer peripheral twisted cutting edge such as a ball end mill or a radius end mill.

DESCRIPTION OF SYMBOLS 1 Unequal lead end mill 2 Tip cutting edge 3, 4 Outer periphery twist cutting edge 5 Blade part 6 Handle part 7 Wide side discharge groove 7a Groove bottom discharge groove bottom 7d Wide side discharge groove bottom depth 8 Short side discharge Groove 8a Groove bottom of the narrow side discharge groove 8d Groove bottom depth of the narrow side discharge groove 11, 12 Round-up portions 13a, 13b, 13c Core thickness diameters of the wide side discharge grooves 14a, 14b, 14c Core thickness α, β Twist angle of outer peripheral cutting edge

Claims (3)

A cutting portion having a cutting edge formed by a tip cutting edge and a peripheral twisting cutting edge; and a handle portion supporting the cutting edge, the twisting angles of the adjacent peripheral cutting edges being different from each other, and chips between the peripheral cutting edges A widened discharge groove in which the width of the discharge groove gradually increases from the tip toward the handle portion, and a reduced width in which the width of the chip discharge groove between the outer peripheral cutting edges gradually decreases from the tip toward the handle portion. In an unequal lead end mill having a side discharge groove,
The groove bottom depth of the wide-side discharge groove gradually decreases from the tip toward the handle portion cut-up portion, and the groove bottom depth of the narrow-width discharge groove gradually increases from the tip toward the handle portion cut-up portion. Unequal lead end mill characterized by   2. The unequal lead according to claim 1, wherein a core thickness diameter with which a groove bottom of the reduced width side discharge groove contacts is larger than a core thickness diameter with which the groove bottom of the wide side discharge groove contacts with the tip. End mill.   The center thickness diameter which the groove bottoms of the said wide width side and the width reduction side discharge groove contact is made the same in the position where the said outer periphery cutting edge becomes an equal division in an axial cross section. Unequal lead end mill.

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