JP2015188979A - end mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an end mill capable of finishing a working surface of material to be shaved in a high quality.SOLUTION: An end mill includes: a shaft-shaped end mill main body 2; a plurality of chip discharge grooves 4 which are gradually extended toward the rear side in the tool rotation direction T as proceeding to the base end side from a tip along an axial line O direction of the end mill main body 2 and are formed at an interval from each other in the circumferential direction; a plurality of outer circumferential blades 6 formed respectively on intersection ridge parts between respective wall surfaces which are turned to the front side in the tool rotation direction T on the plurality of chip discharge grooves 4; and a plurality of bottom blades which are arranged on a tip surface of the end mill main body 2, are respectively connected to tips of the plurality of outer circumferential blades 6 and are extended so as to proceed to the inner side in a radial direction from the tips. Therein, a diameter D1 of rotation locus C1 on one outer circumferential blade 6A among the plurality of outer circumferential blades 6 is larger than a diameter D2 of rotation locus C2 on outer circumferential blades 6B other than one outer circumferential 6A over the whole region along the axial line O direction on which the outer circumferential blade 6 of the end mill main body 2 is formed.

Description

  The present invention relates to an end mill.

Conventionally, as this type of end mill, for example, as shown in Patent Document 1 below, a plurality of chips are discharged on the outer periphery of the end portion of the end mill body rotated about the axis line from the end of the end mill body toward the base end side. Grooves are formed and outer peripheral blades are formed on the outer peripheral side ridges of the wall surfaces facing the tool rotation direction of these chip discharge grooves, respectively, and the end face of the end mill main body is on the inner peripheral side from the distal ends of these outer peripheral blades. There is known one in which a bottom blade extending in the direction is formed.
The end mill is fed in a direction crossing the axis while being rotated in the direction of rotation of the tool to cut the work material.

JP 2013-202748 A

However, the conventional end mill has the following problems.
That is, when side milling or deep grooving is performed on a work material using an end mill, streak-like cut marks extending in the tool feed direction are left on the work surface of the work material with an interval in the axial direction of the end mill. There was a thing. And, the quality of the machined surface is impaired by visually recognizing the difference in reflection (difference in the appearance of light and dark depending on the angle of the metallic luster) of the cut mark itself and the upper and lower machined parts sandwiching the cut mark. It was.

  This invention is made | formed in view of such a situation, Comprising: It aims at providing the end mill which can finish the processed surface of a work material in high quality.

In order to solve such problems and achieve the above object, the present invention proposes the following means.
That is, the end mill of the present invention is disposed at least at the distal end portion of the end mill body having an axial shape and the outer periphery of the end mill body, and gradually moves around the axis line from the distal end along the axial direction of the end mill body toward the proximal end side. Extending in the circumferential direction along the tool rotation direction and a plurality of chip discharge grooves formed at intervals in the circumferential direction, and the front of the tool rotation direction in the plurality of chip discharge grooves A plurality of outer peripheral blades formed at each crossing ridge line portion between each wall surface facing and the outer peripheral surface of the end mill main body, and arranged on the front end surface of the end mill main body, respectively connected to the front ends of the plurality of outer peripheral blades, A plurality of bottom blades extending from the tip to the inside in the radial direction perpendicular to the axis, and the outer peripheral blade of the end mill body is formed Of the plurality of outer peripheral blades, the diameter of the rotation trajectory centered on the axis of one of the plurality of outer peripheral blades is greater than the diameter of the rotation trajectory of the outer peripheral blades other than the one outer peripheral blade. It is large.

In order to achieve the above object, the inventor of the present invention has earnestly studied, and as a result, has obtained the following knowledge.
That is, when performing side processing or deep grooving on a work material using an end mill, the work surface of the work material is finished by a plurality of outer peripheral blades. Specifically, due to the influence of runout accuracy that occurs when the end mill is mounted on the spindle of a machine tool, etc., the work surface of the work material is finished with a different outer peripheral edge at each part along the axial direction of the end mill. Has been. For this reason, streak-like cutting marks extending in the tool feed direction are formed between the parts of the processed surfaces finished by different outer peripheral blades, and the cutting marks themselves and the reflection of the upper and lower processed surface parts sandwiching the cutting marks are reflected. The quality of the processed surface was impaired by the difference being visually recognized.

The present invention has been made based on such knowledge, and centered on the axis of one outer peripheral blade among the plurality of outer peripheral blades over the entire region along the axial direction in which the outer peripheral blade of the end mill body is formed. Since the diameter of the rotation trajectory is larger than the diameter of the rotation trajectory of an outer peripheral blade other than the one outer peripheral blade (hereinafter referred to as another outer peripheral blade), the work surface of the work material is finished only by the one outer peripheral blade. It is supposed to be.
That is, since the protrusion amount that one outer peripheral blade protrudes radially outward from the axis among the plurality of outer peripheral blades is larger than the protrusion amount of the other outer peripheral blades, the machining surface of the work material is Then, finishing is performed by the predetermined one outer peripheral blade.

As a result, streak-like cutting marks are formed on the processed surface of the work material, and reflection differences (differences in the appearance of light and dark metallic luster) occur on the upper and lower processed surface portions sandwiching the cutting marks. Can be reliably prevented.
Therefore, according to the present invention, it is possible to finish the processed surface of the work material with high quality.
Note that the above-described effects of the present invention cannot be obtained if two or more peripheral cutting edges for finishing are provided (since cutting marks are generated on the processing surface between the peripheral cutting edges), 1 The effect is achieved by finishing with only one outer peripheral blade.

  Moreover, in the end mill of the present invention, among the plurality of outer peripheral blades, the one outer peripheral blade protrudes more outward in the radial direction than the outer peripheral blades other than the one outer peripheral blade. It may be 30 μm.

  As described above, among the plurality of outer peripheral blades, the protrusion amount of the one outer peripheral blade toward the radially outer side with respect to the other outer peripheral blades is set in the range of 5 to 30 μm, and thus described above. The action and effect can be obtained remarkably.

Specifically, when the protruding amount is less than 5 μm, the other outer peripheral blade is more radially outward than the one outer peripheral blade due to the influence of runout accuracy that occurs when the end mill is mounted on the spindle of the machine tool or the like. The above-described effects may not be sufficiently obtained due to partial protrusions.
Further, when the protruding amount exceeds 30 μm, the ratio of the cutting load to the one outer peripheral blade for finishing is excessively increased, and there is a possibility that the one outer peripheral blade is damaged (weared or missing) at an early stage. is there.

Further, in the end mill of the present invention, a portion of the outer peripheral surface of the end mill main body that is connected to the rear of the one outer peripheral blade in the tool rotation direction is on a rotation locus centering on the axis of the one outer peripheral blade. A positioned margin may be formed.
Further, in the end mill of the present invention, the outer peripheral surface of the end mill main body is gradually moved from the one outer peripheral blade toward the rear in the tool rotating direction toward the rear portion in the tool rotating direction of the one outer peripheral blade. An outer peripheral flank that is inclined inward in the radial direction is formed, and in contact with the circumference of a rotation locus centering on the axis of the one outer peripheral blade in a cross-sectional view perpendicular to the axis, the one outer periphery An angle between the tangent line passing through the blade and a virtual straight line connecting the rear end in the tool rotation direction of the outer peripheral flank and the one outer peripheral blade may be 5 ° or less.

In this case, an outer peripheral flank surface having a margin or an extremely small clearance angle (5 ° or less) is formed behind the one outer peripheral blade for finishing machining in the tool rotation direction. The effect will result in a higher quality finish.
The “flank angle” when the above-described outer peripheral flank is formed means that the tangent line passing through the one outer peripheral blade, the rear end in the tool rotation direction on the outer peripheral flank, and the one outer peripheral blade are connected. The angle formed between the imaginary straight line and the imaginary straight line (the included angle), and when the outer peripheral flank is linear in a cross-sectional view perpendicular to the axis (planar outer flank, so-called straight line 2) and The case of a convex curve (a convex curved outer peripheral flank, so-called eccentric number 2) is included.

  In the end mill of the present invention, the width of the margin along the circumferential direction may be 0.02 to 0.2 mm.

In this case, the above-mentioned vanishing effect can be stably obtained, and the processing accuracy can be maintained well.
Specifically, if the width along the circumferential direction of the margin is less than 0.02 mm, the effect may be lost early due to initial cutting wear. Moreover, when the width along the circumferential direction of the margin exceeds 0.2 mm, the cutting resistance increases, and there is a risk of processing dimension defects and processing surface deformation.

  Further, in the end mill of the present invention, the outer peripheral flank is formed with a plurality of grinding strips that reach the one outer peripheral blade and extend away from the outer peripheral blade and are parallel to each other. The strip may be inclined at an angle of 45 ° or more with respect to the tool rotation direction.

  When the cutting edge of the one outer peripheral blade is viewed microscopically, the one outer peripheral blade has a plurality of grinding strips (formed when the outer peripheral flank is ground with a grindstone during manufacture of the end mill. An uneven shape is formed by grinding lines). According to the above configuration of the present invention, since these grinding strips are greatly inclined at an angle of 45 ° or more with respect to the tool rotation direction, the above-described uneven shape of the cutting edge is transferred to the processing surface of the work material. It has become difficult.

  Specifically, in the vicinity of one outer peripheral edge, the ridge line of the grinding strip and the side wall of the grinding strip adjacent to the ridge line face the processing surface of the work material from the rear in the tool rotation direction (exposed to the processing surface). In addition, since the ridgeline and the side wall of these grinding strips can be flattened while rubbing the processed surface, finishing can be performed.

  Unlike the above configuration, for example, a plurality of grinding strips may be inclined at an angle of less than 45 ° with respect to the tool rotation direction, or may extend (parallel) along the tool rotation direction. The uneven shape of these grinding strips is easily transferred as it is to the work surface of the work material, and the unevenness difference (surface roughness) increases, so that the above-described effects may not be obtained.

  According to the end mill of the present invention, the processed surface of the work material can be finished with high quality.

It is a side view which shows the end mill which concerns on one Embodiment of this invention. It is a figure which shows the AA cross section of FIG. It is a figure which expands and shows the B section of FIG. It is a figure which shows the some grinding strip formed in the flank which continues to one outer peripheral blade, and represents the microscopic cross-sectional shape (uneven | corrugated shape) of this outer peripheral blade. It is a figure which shows the some grinding strip formed in the flank which continues to one outer peripheral blade, and represents the microscopic cross-sectional shape (uneven | corrugated shape) of this outer peripheral blade. It is the longitudinal cross-sectional view which expands and shows the process surface of the workpiece cut by the end mill, (a) The Example of this invention, (b) The conventional comparative example is shown.

Hereinafter, an end mill 1 according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the end mill 1 of the present embodiment has an end mill body 2 having an axial shape. Specifically, the end mill main body 2 has a substantially cylindrical shape, and a blade portion 3a is formed at least at a tip portion along the axis O direction of the end mill main body 2, and a portion other than the blade portion 3a is connected to the shank portion 3b. Has been.

  In the end mill 1, a cylindrical shank portion 3 b in the end mill body 2 is gripped by a main shaft of a machine tool and rotated in a tool rotation direction T around an axis O, thereby cutting a work material made of a metal material or the like. Used for machining (turning). Further, along with the rotation, a feed is given in the direction intersecting the axis O, and the side surface processing, deep grooving processing, front face cutting processing and the like are performed on the work material by the blade portion 3a.

  Here, in this specification, among the directions of the axis O of the end mill body 2, the direction toward the blade 3 a (downward in FIG. 1) is the tip side and the direction opposite to the blade 3 a (the shank 3 b side). The direction toward the upper side in FIG. A direction orthogonal to the axis O is referred to as a radial direction, and a direction around the axis O is referred to as a circumferential direction. Of the circumferential directions, the direction in which the end mill body 2 is rotated during cutting is called the tool rotation direction T (or the front of the tool rotation direction T), and the direction toward the opposite side of the tool rotation direction T is the tool rotation. It is called the rear of the direction T.

On the outer periphery of the blade portion 3a, a plurality of chip discharge grooves 4 are formed at intervals in the circumferential direction. These chip discharge grooves 4 are disposed at least at the tip of the outer periphery of the end mill body 2 and specifically correspond to the formation region of the blade 3a.
The chip discharge groove 4 opens at the distal end surface of the end mill body 2 and gradually twists and extends toward the rear in the tool rotation direction T from the distal end surface toward the proximal end side. In the end mill 1 of the present embodiment, the four chip discharge grooves 4 are formed at intervals (equal intervals or unequal intervals) in the circumferential direction.

  An outer peripheral blade 6 is formed on each cross ridge line portion between each wall surface facing the front in the tool rotation direction T in the plurality of chip discharge grooves 4 and the outer peripheral surface of the end mill body 2. The wall surface of the chip discharge groove 4 is a rake face of the outer peripheral blade 6.

  Specifically, the outer peripheral blade 6 is located at the rear end in the tool rotation direction T among the wall surface (inner surface of the groove) of the chip discharge groove 4 and faces the front in the tool rotation direction T, and the blade portion 3a. Are formed at the intersecting ridge line portion with the outer peripheral flank 5 facing outward in the radial direction.

  Four outer peripheral blades 6 are formed on the blade portion 3a at intervals in the circumferential direction. These outer peripheral blades 6 are leads equal to the respective chip discharge grooves 4 adjacent to the front in the tool rotation direction T of each outer peripheral blade 6, and gradually toward the rear in the tool rotation direction T toward the proximal end side of the end mill body 2. It is twisted and extended. A rotation locus formed by rotating the outer peripheral blade 6 around the axis O is a substantially cylindrical surface centered on the axis O.

  Four outer peripheral flank surfaces 5 are formed between the four chip discharge grooves 4 on the outer peripheral surface of the blade portion 3a. The outer peripheral flank 5 is gradually inclined inward in the radial direction from the outer peripheral blade 6 toward the rear in the tool rotation direction T. The width of the outer peripheral flank 5 is substantially constant along the extending direction of the outer peripheral blade 6.

  A groove-like (concave) gash 7 is formed at the tip of the chip discharge groove 4 so as to cut out the wall surface of the chip discharge groove 4 inward in the radial direction. The gash 7 extends along the radial direction at the tip of the chip discharge groove 4, and the radially inner end is disposed in the vicinity of the axis O.

  A bottom blade (tip blade) 9 is formed on each of the front edge side crests of the wall surface facing forward in the tool rotation direction T in the gash 7 (ridge line portion extending in the radial direction along the front edge of the wall surface). . The wall surface of the gash 7 is a rake face of the bottom blade 9.

  Specifically, the bottom blade 9 is located at the rear end portion in the tool rotation direction T of the wall surface (the inner surface of the groove) of the gash 7 and faces the front in the tool rotation direction T, and the tip of the blade portion 3a. It is formed at the intersection ridgeline part with the tip flank 8 facing the side.

  The plurality of bottom blades 9 are disposed on the front end surface of the end mill main body 2, are connected to the front ends of the plurality of outer peripheral blades 6, and extend from the front ends toward the inside in the radial direction. The set of the continuous outer peripheral edge 6 and the bottom edge 9 forms a series of cutting edges so as to form an L shape in which the long side is twisted. A convex curved corner blade may be formed between the outer peripheral edge 6 and the bottom edge 9 in the series of cutting edges.

  In addition, the rotation locus formed by the bottom blade 9 rotating around the axis O is very slight toward one base plane orthogonal to the axis O or gradually toward the base end side in the axis O direction as it goes radially inward. It is located on one concave conical surface that is recessed.

  Four tip flank surfaces 8 are formed between the tip portions (gash 7) of the four chip discharge grooves 4 on the tip surface of the blade portion 3a. The tip flank 8 is gradually inclined toward the base end side in the direction of the axis O as it goes rearward from the bottom blade 9 in the tool rotation direction T.

Although not particularly illustrated, a coolant hole serving as a coolant (oil-based or water-soluble cutting agent) flow path may be formed inside the end mill body 2. The coolant hole opens at the base end face of the end mill body 2 and extends toward the tip end side, branches from the trunk path into a plurality of branches, and opens at the chip discharge groove 4 and the tip end face of the blade portion 3a.
The end mill 1 of the present embodiment configured as described above is a square end mill having a blade portion 3a having four cutting edges. The number of cutting blades of the blade portion 3a (the number of sets of the bottom blade 9 and the outer peripheral blade 6 constituting one continuous cutting blade) is not limited to the four blades described in the present embodiment.

  As shown in FIG. 2, the end mill 1 of the present embodiment includes a plurality of outer peripheral blades 6 over the entire region along the axis O direction in which the outer peripheral blade 6 of the end mill body 2 is formed (that is, over the entire region of the blade portion 3 a). Among them, the diameter D1 of the rotation trajectory C1 around the axis O in one outer peripheral blade 6A is the rotation trajectory in the outer peripheral blade 6B other than the one outer peripheral blade 6A (hereinafter also referred to as other outer peripheral blade 6B). It is larger than the diameter D2 of C2.

Specifically, in the present embodiment, four outer peripheral blades 6 are provided on the blade portion 3a of the end mill body 2, and the radial position of one outer peripheral blade 6A among these outer peripheral blades 6 is other than the outer peripheral blade 6A. It arrange | positions in the radial direction outer side with respect to the radial direction position in the other (three) outer peripheral blades 6B. In other words, the distance (radius) from the axis O along the radial direction of one outer peripheral blade 6A is made larger than the distance (radius) from the axis O along the radial direction of the other outer peripheral blade 6B.
In addition, the radial position (distance from the axis O along the radial direction to each outer peripheral blade 6B, that is, the radius) of the other outer peripheral blades 6B is the same.

  Moreover, the protrusion amount P by which one outer peripheral blade 6A protrudes radially outward from the other outer peripheral blades 6B among the plurality of outer peripheral blades 6 is set within a range of 5 to 30 μm.

  Further, in FIG. 3, the outer peripheral flank 5 </ b> A disposed at a portion of the outer peripheral surface of the end mill body 2 that is connected to the rear of the tool rotating direction T of one outer peripheral blade 6 </ b> A is connected to the tool rotating direction T In this respect, the outer peripheral flank 5A has the same configuration as the outer peripheral flank 5B connected to the rear in the tool rotation direction T of the other outer peripheral blade 6B. However, it has a special configuration (different configuration) in the following points.

That is, in a cross-sectional view perpendicular to the axis O shown in FIG. 3, the tool rotation of the tangent line L passing through the circumference of the rotation locus C1 of one outer peripheral blade 6A and passing through the one outer peripheral blade 6A and the tool of the outer peripheral flank 5A is performed. An angle (that is, a relief angle) θ sandwiched between a virtual straight line (corresponding to a straight line portion indicated by reference numeral “5A (5)” in FIG. 3) connecting the rear end of the direction T and the one outer peripheral blade 6A. It is set to a small angle of 5 ° or less. Specifically, the clearance angle (angle θ) at the outer peripheral flank 5A of one outer peripheral blade 6A is set smaller than the clearance angle at the outer peripheral flank 5B of the other outer peripheral blade 6B.
The “angle (relief angle) θ” in the present specification refers to the tangent L passing through the one outer peripheral blade 6A, the rear end of the tool rotation direction T on the outer peripheral flank 5A, and the one outer peripheral blade. 6A is an angle (an included angle) θ formed between the imaginary straight line 6A and the imaginary straight line 6A, the outer peripheral flank 5A is a straight line in a cross-sectional view perpendicular to the axis O shown in FIG. And the case where the outer peripheral flank 5A has a convex curve shape (the convex outer peripheral flank 5A, so-called eccentric second).
In the example of the present embodiment, as shown in the drawing, the outer peripheral flank 5A has a second straight line.

  More specifically, in FIG. 3, the outer peripheral flank 5 </ b> A has first to third flank surfaces whose escaping angles increase stepwise (sequentially) from one outer peripheral blade 6 </ b> A toward the rear in the tool rotation direction T. The angle θ indicates a clearance angle formed between the first clearance surface portion adjacent to the peripheral blade 6A on the peripheral clearance surface 5A and the tangent L. In the illustrated example, of the first to third flank portions of the outer peripheral flank 5A, the first and second flank portions are arranged between the rotation trajectories C1 and C2 along the radial direction, and the third flank The surface portion is located on the rotation locus C2 and intersects the rotation locus C2.

Although not particularly illustrated, the outer peripheral flank 5A is positioned on the rotation locus C1 of one outer peripheral blade 6A instead of the first flank portion (that is, partially coincides with the rotation locus C1). A margin may be formed. That is, the margin is arranged at a position corresponding to the first flank portion adjacent to the rear of the outer peripheral blade 6A in the tool rotation direction T in the outer peripheral flank 5A shown in FIG. It is formed so as to form part of the surface.
When a margin is formed on the outer peripheral flank 5A, the width along the circumferential direction of the margin is preferably set within a range of 0.02 to 0.2 mm.

  Further, in FIG. 2, the outer peripheral flank 5B has first and second flank surfaces whose flank angle increases stepwise (sequentially) from the other outer peripheral blade 6B toward the rear in the tool rotation direction T. In the outer peripheral flank 5B, the flank angle of the first flank portion disposed adjacent to the outer peripheral blade 6B is larger than the angle θ of the outer peripheral flank 5A.

  As shown in FIG. 4, the outer peripheral flank 5 </ b> A connected to one outer peripheral blade 6 </ b> A has a plurality of grindings that reach the one outer peripheral blade 6 </ b> A and extend away from the outer peripheral blade 6 </ b> A and are parallel to each other. Article 10 is formed. These grinding strips 10 are grinding lines formed when the outer peripheral flank 5A is ground with a grindstone when the end mill 1 is manufactured. The plurality of grinding strips 10 extend at an angle (inclination angle) α of 45 ° or more with respect to the tool rotation direction T.

  Moreover, these grinding strips 10 are inclined with respect to the tool rotation direction T, so that in a cross-sectional view perpendicular to the tool rotation direction T (see the EE cross section and the FF cross section in FIG. 4), The ridgeline of each grinding strip 10 also extends in a direction intersecting with the tool rotation direction T at an angle α with respect to the tool rotation direction T. The ridge line of the grinding strip 10 and the side wall of the grinding strip 10 adjacent to the ridge line are opposed to the work surface of the work material from the rear in the tool rotation direction T and can be contacted. Therefore, in the vicinity of the outer peripheral edge 6A, the ridge line and the side wall of the grinding strip 10 are involved in cutting to finish the processed surface.

According to the end mill 1 of this embodiment described above, one outer peripheral blade among the plurality of outer peripheral blades 6 extends over the entire region along the axis O direction (the entire blade portion 3a) where the outer peripheral blade 6 of the end mill body 2 is formed. Since the diameter D1 of the rotation trajectory C1 in 6A is larger than the diameter D2 of the rotation trajectory C2 in the other outer peripheral blade 6B, the processing surface of the work material is finished only by the one outer peripheral blade 6A. .
That is, since the protrusion amount that one outer peripheral blade 6A protrudes outward in the radial direction from the axis O among the plurality of outer peripheral blades 6 is larger than the protrusion amount of the other outer peripheral blade 6B. The processed surface is finished by the predetermined one outer peripheral edge 6A.

As a result, streak-like cutting marks are formed on the processed surface of the work material, and the difference in reflection (brightness and darkness of the metallic luster of the upper and lower processing surfaces between the cutting marks). It is possible to reliably prevent the difference in appearance).
Therefore, according to this embodiment, it is possible to finish the processed surface of a work material in high quality.
In addition, the above-mentioned effect by this embodiment cannot be obtained if the outer peripheral blade 6A for finishing is provided two or more (Because a cutting trace arises in the processing surface between these outer peripheral blades 6A). ) The effect is achieved by finishing with only one outer peripheral edge 6A.

Moreover, in this embodiment, since the protrusion amount P which one outer peripheral blade 6A protrudes toward the outer side of radial direction rather than the other outer peripheral blade 6B among several outer peripheral blades 6 is 5-30 micrometers. The obtained effects can be obtained remarkably.
Specifically, when the protrusion amount P is less than 5 μm, the other outer peripheral blade 6B is more than the one outer peripheral blade 6A due to the influence of runout accuracy that occurs when the end mill 1 is mounted on the spindle of the machine tool or the like. There is a possibility that the above-described effects may not be sufficiently obtained, for example, by partially protruding outward in the radial direction.
Further, when the protruding amount P exceeds 30 μm, the ratio of the cutting load to the one outer peripheral edge 6A for finishing is excessively large, and the one outer peripheral edge 6A is damaged early (worn or missing). There is a risk.

Further, in the present embodiment, in a cross-sectional view perpendicular to the axis O, between the tangent line L that passes through the circumference of the rotation locus C1 of one outer peripheral blade 6A and passes through the one outer peripheral blade 6A, and the outer peripheral flank 5A Since the formed angle θ is 5 ° or less, or the margin is formed on the outer peripheral flank 5A so as to be positioned on the rotation locus C1 of one outer peripheral blade 6A, the following effects are obtained.
That is, in this case, the outer peripheral flank 5A having a margin or an extremely small clearance angle (5 ° or less) is formed behind the tool rotation direction T of one outer peripheral blade 6A for finishing. The surface will be finished to a higher quality by the vanish effect.

In the case where a margin is provided on the outer peripheral flank 5A, if the width along the circumferential direction of the margin is 0.02 to 0.2 mm, the above-described vanishing effect can be stably obtained and the processing accuracy can be improved. Is maintained well.
Specifically, if the width along the circumferential direction of the margin is less than 0.02 mm, the effect may be lost early due to initial cutting wear. Moreover, when the width along the circumferential direction of the margin exceeds 0.2 mm, the cutting resistance increases, and there is a risk of processing dimension defects and processing surface deformation.

Further, since the plurality of grinding strips 10 formed on the outer peripheral flank 5A are inclined at an angle α of 45 ° or more with respect to the tool rotation direction T, the following effects are obtained.
That is, when the cutting edge of one outer peripheral blade 6A is viewed microscopically as shown in FIG. 4, the one outer peripheral blade 6A is formed with uneven shapes by a plurality of grinding strips 10 along the blade length direction. ing. According to the configuration described in the present embodiment, since the grinding strip 10 is greatly inclined at an angle α of 45 ° or more with respect to the tool rotation direction T, the uneven shape of the cutting edge is the work material. It is difficult to be transferred to the processed surface.

  Specifically, in the vicinity of the outer peripheral edge 6A, the ridge line of the grinding strip 10 and the side wall of the grinding strip 10 adjacent to the ridge line face the processing surface of the work material from the rear in the tool rotation direction T (with respect to the processing surface). The ridgeline and the side wall of the grinding strip 10 can be flattened while rubbing the processed surface and finished.

  In addition, the extending direction of the plurality of grinding strips 10 formed on the outer peripheral flank 5A is not limited to the above-described angle α of 45 ° or more, for example, inclined at an angle α of less than 45 °, It may extend along (in parallel with) the tool rotation direction T.

Here, FIG. 5 shows a modification of the present embodiment. In this modification, the plurality of grinding strips 10 extend in parallel to the tool rotation direction T (that is, the angle α is 0 °).
However, in this case, as shown in the GG cross section and the HH cross section of FIG. 5, the uneven shape of the plurality of grinding strips 10 appearing at the cutting edge of the outer peripheral blade 6A is rearward in the tool rotation direction T from the outer peripheral blade 6A. Will continue at the same position along the blade length direction. Specifically, an imaginary straight line (a straight line indicated by a two-dot chain line in FIG. 5) extending along the tool rotation direction T through the ridge line (vertex of the convex line) of the grinding line 10 in the GG cross section of FIG. It passes through the ridge line of the grinding strip 10 in the HH cross section located behind the GG cross section in the tool rotation direction T.

  That is, when the angle α is less than 45 ° or 0 ° compared to the case where the angle α is set to 45 ° or more, the ridge line and the side wall of the grinding strip 10 face the processing surface of the work material. Since the uneven shape of the plurality of grinding strips 10 is easily transferred as it is to the processed surface of the work material and the unevenness difference (surface roughness) is increased, the above-described effects may not be obtained. .

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above-described embodiment, the end mill 1 has been described using a four-blade square end mill, but the present invention is not limited to this. That is, the number of blades of the end mill 1 may be three blades other than four blades, or five or more blades. The end mill 1 may be a radius end mill other than the square end mill.

  In addition, in the range which does not deviate from the meaning of this invention, you may combine each structure (component) demonstrated by the above-mentioned embodiment, a modified example, a note, etc., addition of a structure, omission, substitution, others It can be changed. Further, the present invention is not limited by the above-described embodiments, and is limited only by the scope of the claims.

  Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to this embodiment.

As an example of the present invention, the four-blade end mill 1 described in the above-described embodiment was manufactured. Specifically, in the end mill body 2 made of cemented carbide and having an outer diameter of the blade portion 3a of φ25 mm, the radial position of one outer blade 6A among the plurality of outer blades 6 over the entire area of the blade portion 3a. However, what was arrange | positioned in the radial direction outer side rather than the radial position of the other three outer periphery blades 6B was prepared.
On the other hand, as an end mill of a conventional comparative example, all the peripheral positions in the radial direction of the four outer peripheral blades formed on the blade portion were set to be the same, and the other specifications were the same as those in the above-described example.

  Then, using the end mills of these examples and comparative examples, the work material: SKD11 (60HRC) is cut, and the state of unevenness along the axis O direction in the longitudinal section of the work surface of the work material is confirmed. did. The cutting conditions were as follows: cutting speed: 75 m / min, feed per tooth: 0.1 mm / tooth, axial direction (axis O direction) cutting: 30 mm, radial direction (radial direction) cutting: 0.2 mm.

As shown in the test results shown in FIG. 6, in the example of FIG. 6A, the processed surface of the work material (work) was formed in a substantially linear cross section, and no cutting trace was observed.
On the other hand, in the comparative example of FIG. 6B, the uneven shape appeared clearly on the processed surface of the work material, and a plurality of cutting marks (cutting lines) M were confirmed.

DESCRIPTION OF SYMBOLS 1 End mill 2 End mill main body 4 Chip discharge groove 5A Outer peripheral flank of one outer peripheral blade 6 Outer peripheral blade 6A One outer peripheral blade 6B Other outer peripheral blades (outer peripheral blades other than one outer peripheral blade)
9 Bottom edge 10 Grinding strip C1, C2 Rotating locus D1, D2 Diameter L Tangential O Axis P Projection amount T Tool rotation direction α angle (Inclination angle of grinding strip)
θ angle (clearance angle)

Claims (6)

A shaft-shaped end mill body,
Of the outer periphery of the end mill body, it is disposed at least at the distal end portion, and gradually extends toward the rear in the tool rotation direction in the circumferential direction along the axis line from the distal end along the axial direction of the end mill body toward the proximal end side. A plurality of chip discharge grooves formed at intervals in the circumferential direction;
A plurality of outer peripheral blades formed respectively at the crossing ridge line part of each wall surface facing the front of the tool rotation direction in the plurality of chip discharge grooves and the outer peripheral surface of the end mill body;
A plurality of bottom blades disposed on the front end surface of the end mill body, respectively connected to the front ends of the plurality of outer peripheral blades, and extending from the front end toward the inside in the radial direction perpendicular to the axis,
The diameter of the rotation trajectory centered on the axis of one outer peripheral blade among the plurality of outer peripheral blades is the one other than the one outer peripheral blade over the entire region along the axial direction in which the outer peripheral blade of the end mill body is formed. An end mill characterized in that it is larger than the diameter of the rotation trajectory of the outer peripheral blade. The end mill according to claim 1,
Of the plurality of outer peripheral blades, the one outer peripheral blade protrudes outward in the radial direction from the outer peripheral blades other than the one outer peripheral blade, and has a protrusion amount of 5 to 30 μm. End mill. The end mill according to claim 1 or 2,
In the outer peripheral surface of the end mill main body, a margin that is located on a rotation locus centering on the axis of the one outer peripheral blade is formed in a portion that continues to the rear of the one outer peripheral blade in the tool rotation direction. End mill characterized by that. The end mill according to claim 1 or 2,
Of the outer peripheral surface of the end mill body, the one outer peripheral blade is connected to the rear of the tool rotation direction toward the rear in the tool rotation direction and gradually toward the inner side in the radial direction. An inclined outer flank is formed,
In a cross-sectional view perpendicular to the axis,
A tangent line that is in contact with the circumference of the rotation trajectory centered on the axis of the one outer peripheral blade and passes through the one outer peripheral blade;
An end mill characterized in that an angle sandwiched between a rear end of the outer peripheral flank in the tool rotation direction and a virtual straight line connecting the one outer peripheral blade is 5 ° or less. The end mill according to claim 3, wherein
The end mill is characterized in that a width of the margin along the circumferential direction is 0.02 to 0.2 mm. The end mill according to claim 4, wherein
The outer peripheral flank is formed with a plurality of grinding strips that reach the one outer peripheral blade and extend in a direction away from the outer peripheral blade and are parallel to each other,
The plurality of grinding strips are inclined at an angle of 45 ° or more with respect to the tool rotation direction.

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