JP6852439B2 - End mill body of replaceable cutting edge end mill and end mill with replaceable cutting edge - Google Patents

End mill body of replaceable cutting edge end mill and end mill with replaceable cutting edge Download PDF

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JP6852439B2
JP6852439B2 JP2017024268A JP2017024268A JP6852439B2 JP 6852439 B2 JP6852439 B2 JP 6852439B2 JP 2017024268 A JP2017024268 A JP 2017024268A JP 2017024268 A JP2017024268 A JP 2017024268A JP 6852439 B2 JP6852439 B2 JP 6852439B2
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end mill
groove
axis
cutting edge
outer peripheral
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JP2018130774A (en
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隆行 萩原
隆行 萩原
秀彦 長屋
秀彦 長屋
茂 石森
茂 石森
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Mitsubishi Materials Corp
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Description

本発明は、先端外周部に形成されたインサート取付座に着脱可能に取り付けられる複数の切削インサートの外周側に向けられる切刃によって切削加工を行う円柱状の刃先交換式エンドミルのエンドミル本体、および該刃先交換式エンドミルのエンドミル本体の上記インサート取付座に切削インサートが着脱可能に取り付けられた刃先交換式エンドミルに関するものである。 The present invention relates to an end mill body of a columnar blade tip exchange type end mill that performs cutting with a cutting edge directed to the outer peripheral side of a plurality of cutting inserts that are detachably attached to an insert mounting seat formed on the outer peripheral portion of the tip. The present invention relates to a blade tip replaceable end mill in which a cutting insert is detachably attached to the insert mounting seat of the end mill main body of the blade tip replaceable end mill.

このようなエンドミル本体に複数の切削インサートが取り付けられた刃先交換式エンドミルとして、例えば特許文献１には、切削インサートのエンドミル本体基端側に隣接してエンドミル本体の軸線に交差する方向に切屑排出用の溝が形成され、この溝は、横断面が円弧状、Ｖ字形、Ｕ字形とされているものや、エンドミル本体の軸線方向に隣接する２つの切削インサートの間に溝が形成され、この溝は、横断面が円弧状、Ｖ字形、Ｕ字形とされているとともに、軸線に交差する方向に延在しているものが記載されている。 As such an end mill with a replaceable cutting edge in which a plurality of cutting inserts are attached to the main body of the end mill, for example, in Patent Document 1, for example, in Patent Document 1, chips are discharged in a direction adjacent to the base end side of the end mill main body of the cutting insert and intersecting the axis of the end mill main body. A groove is formed for the end mill, and the cross section is arcuate, V-shaped, or U-shaped, or a groove is formed between two cutting inserts adjacent to each other in the axial direction of the end mill body. The groove has an arc-shaped, V-shaped, and U-shaped cross section, and extends in a direction intersecting the axis.

このような刃先交換式エンドミルでは、チップポケットを構成する軸線方向に延びる１つの凹溝（切屑排出溝）に、複数の切削インサートが軸線方向に間隔をあけて取り付けられている場合に、切削インサートの外周側に向けられた切刃によって生成された切屑が、軸線方向に隣接する切削インサートの間の隙間からエンドミル本体の外周面に入り込んでも、上記溝内を流れてスムーズに排出されて切屑詰まりを生じることがないので、被削材の加工面やエンドミル本体と干渉して擦過することもなく、切削インサートの欠損や切屑の溶着を招くこともない。 In such an end mill with a replaceable cutting edge, when a plurality of cutting inserts are attached to one concave groove (chip discharge groove) extending in the axial direction constituting the tip pocket at intervals in the axial direction, the cutting insert Even if the chips generated by the cutting edge directed toward the outer peripheral side of the end mill enter the outer peripheral surface of the end mill body through the gap between the cutting inserts adjacent in the axial direction, they flow through the groove and are smoothly discharged and the chips are clogged. Therefore, it does not interfere with the machined surface of the work material or the end mill body and is not scratched, and the cutting insert is not chipped or chips are not welded.

特許第３２７５６９５号公報Japanese Patent No. 3275695

ところで、この特許文献１には、隣接する切削インサートは必ずしも軸線方向に互いに隙間をもって配設される必要はなく、その回転軌跡が互いに重なるように配設されていてもよいとの記載がなされているが、チップポケットとしての１つの切屑排出溝において複数の切削インサートの外周側に向けられた切刃の回転軌跡が互いに重なっていれば、隣接する切削インサートの間に軸線方向に隙間があくことはなく、その隙間から切屑がエンドミル本体の外周面に入り込むこともない。ところが、それにも関わらず、実際に１つの切屑排出溝において切削インサートの切刃の回転軌跡が互いに重なっていても、切屑の一部はエンドミル本体の外周面に入り込んで擦過することにより溶着し、最終的にはエンドミル本体の破損を招くことがある。 By the way, Patent Document 1 describes that adjacent cutting inserts do not necessarily have to be arranged with a gap in the axial direction, and may be arranged so that their rotation loci overlap with each other. However, if the rotation trajectories of the cutting edges directed toward the outer peripheral side of a plurality of cutting inserts overlap each other in one chip discharge groove as a chip pocket, there should be a gap in the axial direction between adjacent cutting inserts. There is no chip, and chips do not enter the outer peripheral surface of the end mill body through the gap. However, in spite of this, even if the rotation loci of the cutting blades of the cutting insert actually overlap each other in one chip discharge groove, a part of the chips enters the outer peripheral surface of the end mill body and is welded by being scraped. Eventually, the end mill body may be damaged.

ここで、刃先交換式エンドミルのエンドミル本体は円柱状であって、特に切り込み量を大きくする場合には切削インサートが取り付けられる先端部の切刃部も長くなるために剛性を確保し難く、切削時に振動やビビリが発生することにより、針状の微細な切屑が生成され易い。その一方で、１つの切屑排出溝において複数の切削インサートの切刃の回転軌跡を重なり合わせるには、これら複数の切削インサートをエンドミル本体の周方向にずらして取り付けなければならない。 Here, the end mill body of the replaceable cutting edge end mill has a columnar shape, and especially when the cutting amount is increased, the cutting edge portion at the tip to which the cutting insert is attached becomes long, so that it is difficult to secure the rigidity, and it is difficult to secure the rigidity at the time of cutting. Due to vibration and chattering, fine needle-shaped chips are likely to be generated. On the other hand, in order to overlap the rotation loci of the cutting edges of the plurality of cutting inserts in one chip discharge groove, the plurality of cutting inserts must be mounted so as to be offset in the circumferential direction of the end mill body.

従って、切刃の全長によって生成される幅広の大きな切屑は、切削インサートのすくい面を擦過して切屑排出溝から排出されるため、エンドミル本体の外周面に巻き込まれることはないが、上述のような針状の微細な切屑は、その一部が切屑排出溝の壁面や大きな切屑に弾かれながら周方向にずらされた切削インサートの間を通ってエンドミル本体の外周面に回り込むおそれがある。そして、このようにエンドミル本体の外周面に回り込んだ微細な切屑が、この外周面と擦過して上述のように溶着すると考えられる。 Therefore, the wide and large chips generated by the total length of the cutting edge scrape the rake face of the cutting insert and are discharged from the chip discharge groove, so that they are not caught in the outer peripheral surface of the end mill body, but as described above. There is a risk that some of the fine needle-shaped chips will pass between the wall surface of the chip discharge groove and the cutting inserts that are displaced in the circumferential direction while being repelled by the large chips and wrap around the outer peripheral surface of the end mill body. Then, it is considered that the fine chips that have wrapped around the outer peripheral surface of the end mill body in this way scrape against the outer peripheral surface and are welded as described above.

本発明は、このような背景の下になされたもので、切削の際に針状の微細な切屑が生成されてエンドミル本体の外周面に回り込んでも、擦過による溶着を防ぐことが可能な刃先交換式エンドミルのエンドミル本体、および該エンドミル本体に切削インサートを着脱可能に取り付けた刃先交換式エンドミルを提供することを目的としている。 The present invention is made under such a background, and even if fine needle-shaped chips are generated during cutting and wrap around the outer peripheral surface of the end mill body, the cutting edge can prevent welding due to scratching. It is an object of the present invention to provide an end mill main body of a replaceable end mill and a cutting edge replaceable end mill in which a cutting insert is detachably attached to the end mill main body.

上記課題を解決して、このような目的を達成するために、本発明の刃先交換式エンドミルのエンドミル本体は、軸線を中心とした円柱状をなして上記軸線回りにエンドミル回転方向に回転させられ、先端外周部に形成されたインサート取付座に着脱可能に取り付けられる切削インサートの外周側に向けられる切刃によって切削加工を行う刃先交換式エンドミルのエンドミル本体であって、このエンドミル本体の先端外周部には、該エンドミル本体の先端から後端側に延びる切屑排出溝が形成されるとともに、この切屑排出溝のエンドミル回転方向を向く壁面に複数の上記インサート取付座が上記軸線方向に並んで形成されていて、これらのインサート取付座に取り付けられる上記切削インサートは周方向にずらされるとともに、外周側に向けられる上記切刃の上記軸線回りの回転軌跡が部分的に重なり合って上記軸線方向に連続し、上記エンドミル本体の外周面には、上記インサート取付座からエンドミル回転方向とは反対側に向けて延びる凹溝が形成され、この凹溝は、上記軸線回りの回転軌跡において、上記軸線方向に隣り合った上記切削インサートの外周側に向けられる上記切刃同士が重なり合う部分が最深部となるように形成され、上記凹溝は、上記軸線に沿った断面において、上記最深部となる上記軸線に平行に延びる溝底面と、この溝底面から上記軸線方向の両端側に向かうに従い互いに離れつつ外周側に延びる２つの溝壁面とを有する台形状に形成されていることを特徴とする。 In order to solve the above problems and achieve such an object, the end mill main body of the cutting edge exchange type end mill of the present invention is formed into a columnar shape centered on the axis and is rotated around the axis in the end mill rotation direction. , An end mill body of an end mill with a replaceable cutting edge that performs cutting with a cutting edge that is directed toward the outer periphery of the cutting insert that is detachably attached to the insert mounting seat formed on the outer periphery of the tip. Is formed with a chip discharge groove extending from the tip end side of the end mill body to the rear end side, and a plurality of the insert mounting seats are formed side by side in the axial direction on the wall surface of the chip discharge groove facing the end mill rotation direction. The cutting inserts attached to these insert mounting seats are shifted in the circumferential direction, and the rotation loci of the cutting edge directed to the outer peripheral side around the axis partially overlap and are continuous in the axis direction. A concave groove extending from the insert mounting seat in the direction opposite to the rotation direction of the end mill is formed on the outer peripheral surface of the end mill main body, and the concave groove is adjacent to the axial direction in the rotation locus around the axis. The portion where the cutting edges overlap each other toward the outer peripheral side of the cutting insert is formed to be the deepest portion, and the concave groove is parallel to the deepest portion in the cross section along the axis. It is characterized in that it is formed in a trapezoidal shape having a groove bottom surface extending from the groove bottom surface and two groove wall surfaces extending toward the outer peripheral side while being separated from each other toward both end sides in the axial direction.

また、本発明の刃先交換式エンドミルは、このようなエンドミル本体における上記インサート取付座に、上記切削インサートが、外周側に向けられる上記切刃の上記軸線回りの回転軌跡が部分的に重なり合って上記軸線方向に連続するように着脱可能に取り付けられていることを特徴とする。 Further, in the blade tip exchange type end mill of the present invention, the rotation locus around the axis of the cutting edge in which the cutting insert is directed toward the outer peripheral side partially overlaps with the insert mounting seat in such an end mill body. It is characterized in that it is detachably attached so as to be continuous in the axial direction.

このように構成される刃先交換式エンドミルのエンドミル本体および刃先交換式エンドミルでは、エンドミル本体の外周面に形成される凹溝が、軸線回りの回転軌跡において、軸線方向に隣り合った切削インサートの外周側に向けられる切刃同士が重なり合う部分が最深部となるように形成されているので、周方向にずらされた隣接する切削インサートの間を通ってエンドミル本体の外周面に回り込む針状の微細な切屑を、この凹溝の最深部に導いて効率的に排出することができる。従って、このような微細な切屑が擦過することによりエンドミル本体の外周面に溶着するのを確実に防ぐことができ、溶着によるエンドミル本体の破損を防止することができる。 In the end mill main body of the blade tip exchange type end mill and the blade tip exchange type end mill configured in this way, the concave groove formed on the outer peripheral surface of the end mill main body is the outer circumference of the cutting insert adjacent to each other in the axial direction in the rotation locus around the axis. Since the part where the cutting blades directed to the side overlap each other is formed to be the deepest part, a fine needle-like shape that wraps around the outer peripheral surface of the end mill body through between adjacent cutting inserts displaced in the circumferential direction. Chips can be guided to the deepest part of this concave groove and discharged efficiently. Therefore, it is possible to reliably prevent welding of such fine chips to the outer peripheral surface of the end mill body due to scratching, and it is possible to prevent damage to the end mill body due to welding.

ここで、隣接する切削インサートの間を通ってエンドミル本体の外周面に回り込む切屑は針状の微細なものであるので、上記凹溝の上記最深部まで深さは０．０７ｍｍ以上と、下限が極浅いものであればよい。逆に、この凹溝の最深部までの深さが大きすぎるとエンドミル本体の折損を招くおそれがあるので、凹溝の最深部までの深さの上限は工具径の５％程度とされるのが望ましい。 Here, since the chips that pass between the adjacent cutting inserts and wrap around the outer peripheral surface of the end mill body are fine needle-shaped ones, the depth to the deepest portion of the concave groove is 0.07 mm or more, and the lower limit is 0.07 mm or more. Anything that is extremely shallow will do. On the contrary, if the depth to the deepest part of the concave groove is too large, the end mill body may be broken. Therefore, the upper limit of the depth to the deepest part of the concave groove is about 5% of the tool diameter. Is desirable.

また、上記凹溝は、上記軸線に沿った断面において、上記最深部となる上記軸線に平行に延びる溝底面と、この溝底面から上記軸線方向の両端側に向かうに従い互いに離れつつ外周側に延びる２つの溝壁面とを有する台形状に形成されている。この凹溝の断面が特許文献１に記載されたような円弧状であると、この円弧の両端部において加工面との間隔が急に狭くなって針状の微細な切屑が噛み込まれ易くなり、やはり溶着を招くおそれがあるのに対して、凹溝が断面台形状であれば、両端部における加工面との間隔は一定の割合で小さくなるだけであるので、噛み込みを生じ難い。 Further, the concave groove extends toward the outer peripheral side while being separated from the bottom surface of the groove extending in parallel with the axis line, which is the deepest portion in the cross section along the axis line, and from the bottom surface of the groove toward both ends in the axial direction. that it is formed in a trapezoidal shape having two groove wall surface. When the cross section of the concave groove has an arc shape as described in Patent Document 1, the distance between the concave groove and the machined surface is suddenly narrowed at both ends of the arc shape, and fine needle-shaped chips are easily bitten. On the other hand, if the concave groove has a trapezoidal cross section, the distance between the both ends and the machined surface is only reduced at a constant rate, so that biting is unlikely to occur.

また、同じく特許文献１に記載されたように断面がＶ字形やＵ字形の溝では、断面台形の凹溝に比べて同じ断面積を確保するには溝深さを深くしなければならなくなるおそれがあってエンドミル本体の剛性を一層損なうことになり、しかもＶ字形の断面では最深部を起点にエンドミル本体の折損が生じ易くなる。これに対しても、断面台形状の凹溝であれば、溝深さを深くしなくても断面積を確保することができ、また溝底面と２つの溝壁面とは鈍角に交差するので、その交差稜線部からエンドミル本体に折損が生じるおそれも少ない。 Further, as also described in Patent Document 1, in a groove having a V-shaped or U-shaped cross section, the groove depth may have to be increased in order to secure the same cross-sectional area as compared with a concave groove having a trapezoidal cross section. Therefore, the rigidity of the end mill body is further impaired, and in the V-shaped cross section, the end mill body is likely to be broken starting from the deepest part. On the other hand, if the groove has a trapezoidal cross section, the cross-sectional area can be secured without increasing the groove depth, and the bottom surface of the groove and the two wall surfaces of the groove intersect at an obtuse angle. There is little possibility that the end mill body will be broken from the crossed ridgeline.

さらに、上述のように切り込み量を大きくする場合には、切削インサートとして長辺と短辺を有する平行四辺形や長方形等の四角形板状のものが用いられ、そのすくい面とされる一方の四角形面の長辺に形成された切刃が外周側に向けられるとともに、このすくい面とは反対側の他方の四角形面が着座面とされてインサート取付座のエンドミル回転方向を向く取付座底面に密着させられ、この取付座底面に、凹溝の溝底面から後端側に延びる上記溝壁面が交差することになる。 Further, when increasing the depth of cut as described above, a quadrangular plate such as a parallelogram or a rectangle having a long side and a short side is used as the cutting insert, and one of the quadrangles as the rake face is used. The cutting edge formed on the long side of the surface is directed to the outer peripheral side, and the other quadrangular surface on the opposite side of the rake surface is used as the seating surface and is in close contact with the bottom surface of the mounting seat facing the end mill rotation direction of the insert mounting seat. The bottom surface of the mounting seat intersects the wall surface of the groove extending from the bottom surface of the groove of the concave groove toward the rear end side.

そこで、このような切削インサートにおけるインサート取付座への着座安定性を確保するには、上記軸線に沿った断面において、上記凹溝の溝底面から後端側に延びる上記溝壁面が該溝底面の後端側への延長線に対してなす傾斜角を、上記凹溝の溝底面から先端側に延びる上記溝壁面が該溝底面の先端側への延長線に対してなす傾斜角よりも小さくして、インサート取付座の取付座底面と凹溝の後端側に延びる溝壁面との交差稜線が、切削インサートの他方の長方形面の外周側に向けられる長辺に沿うようにするのが望ましい。 Therefore, in order to ensure the seating stability of such a cutting insert on the insert mounting seat, the groove wall surface extending from the groove bottom surface of the concave groove to the rear end side in the cross section along the axis line is the groove bottom surface. The inclination angle formed with respect to the extension line to the rear end side is made smaller than the inclination angle formed by the groove wall surface extending from the groove bottom surface of the concave groove to the tip end side with respect to the extension line to the tip end side of the groove bottom surface. Therefore, it is desirable that the intersecting ridge line between the bottom surface of the mounting seat of the insert mounting seat and the groove wall surface extending to the rear end side of the concave groove is along the long side of the other rectangular surface of the cutting insert toward the outer peripheral side.

なお、この場合には、上記軸線に沿った断面において、上記凹溝の溝底面から後端側に延びる上記溝壁面が上記溝底面の後端側への延長線に対してなす傾斜角を４５°以下とすることにより、この後端側に延びる溝壁面と溝底面との交差角をより大きくして、その交差稜線部への切削抵抗による応力集中を抑制し、この交差稜線部を起点とするエンドミル本体の折損等を一層確実に防止することができる。 In this case, in the cross section along the axis, the inclination angle formed by the groove wall surface extending from the groove bottom surface of the concave groove to the rear end side with respect to the extension line to the rear end side of the groove bottom surface is 45. By setting the temperature to ° or less, the intersection angle between the groove wall surface extending to the rear end side and the groove bottom surface is made larger, stress concentration due to cutting resistance on the intersection ridge is suppressed, and this intersection ridge is used as the starting point. It is possible to more reliably prevent breakage of the end mill body.

以上説明したように、本発明によれば、エンドミル本体の振動やビビリによって針状の微細な切屑が生成されて周方向にずらされた切削インサートの間からエンドミル本体の外周面に回り込んでも、軸線回りの回転軌跡において切刃が重なり合う部分に最深部を有する凹溝によって効率的に排出することができ、このような切屑が擦過してエンドミル本体の外周面に溶着することにより破損を生じるのを防止することができる。 As described above, according to the present invention, even if needle-shaped fine chips are generated by vibration or chattering of the end mill body and wrap around from between the cutting inserts displaced in the circumferential direction to the outer peripheral surface of the end mill body. It can be efficiently discharged by the concave groove having the deepest part in the portion where the cutting edges overlap in the rotation locus around the axis, and such chips are scraped and welded to the outer peripheral surface of the end mill body, resulting in damage. Can be prevented.

本発明の刃先交換式エンドミルのエンドミル本体の一実施形態を示す斜視図である。It is a perspective view which shows one Embodiment of the end mill main body of the edge exchange type end mill of this invention. 図１に示す実施形態の正面図である。It is a front view of the embodiment shown in FIG. 図１に示す実施形態の側面図である。It is a side view of the embodiment shown in FIG. 図１に示す実施形態の平面図である。It is a top view of the embodiment shown in FIG. 図１に示すエンドミル本体に切削インサートを取り付けた本発明の刃先交換式エンドミルの一実施形態を示す斜視図である。It is a perspective view which shows one Embodiment of the cutting edge exchange type end mill of this invention which attached the cutting insert to the end mill main body shown in FIG. 図５に示す実施形態の正面図である。It is a front view of the embodiment shown in FIG. 図５に示す実施形態の側面図である。It is a side view of the embodiment shown in FIG. 図５に示す実施形態の平面図である。It is a top view of the embodiment shown in FIG. 図５ないし図８に示す実施形態における凹溝と切削インサートのすくい面の軸線回りの回転軌跡を示す図である。5 is a diagram showing a rotation locus around the axis of the concave groove and the rake face of the cutting insert in the embodiment shown in FIGS. 5 to 8. 図５ないし図８に示す実施形態における凹溝と切削インサートの着座面の軸線回りの回転軌跡を示す図である。5 is a diagram showing a rotation locus around the axis of the concave groove and the seating surface of the cutting insert in the embodiment shown in FIGS. 5 to 8.

図１ないし図４は、本発明の刃先交換式エンドミルのエンドミル本体の一実施形態を示すものであり、図５ないし図１０は、この実施形態のエンドミル本体に切削インサートを取り付けた本発明の刃先交換式エンドミルの一実施形態を示すものである。本実施形態のエンドミル本体１は、鋼材等の金属材料により形成されて、先端部（図３および図４、図７および図８において左側部分）が後端部（図３および図４、図７および図８において右側部分）よりも僅かに小径とされた軸線Ｏを中心とする多段円柱状をなしている。 1 to 4 show an embodiment of an end mill main body of the end mill with a replaceable cutting edge of the present invention, and FIGS. 5 to 10 show a cutting edge of the present invention in which a cutting insert is attached to the end mill main body of the present embodiment. It shows one embodiment of a replaceable end mill. The end mill main body 1 of the present embodiment is formed of a metal material such as a steel material, and the front end portion (left portion in FIGS. 3 and 4, 7 and 8) is the rear end portion (FIGS. 3 and 4, 7). And, in FIG. 8, it has a multi-stage columnar shape centered on the axis O, which is slightly smaller in diameter than the right side portion).

このエンドミル本体１の上記先端部は、上記切削インサートが取り付けられる切刃部２とされるとともに、上記後端部はシャンク部３とされる。こうしてエンドミル本体１の切刃部２に切削インサートが取り付けられて構成された本実施形態の刃先交換式エンドミルは、シャンク部３が工作機械の主軸に把持されて軸線Ｏ回りにエンドミル回転方向Ｔに回転されつつ、この軸線Ｏに交差する方向に送り出されて、被削材に溝加工や肩削り加工を施す。 The tip portion of the end mill main body 1 is a cutting edge portion 2 to which the cutting insert is attached, and the rear end portion is a shank portion 3. In the blade tip exchange type end mill of the present embodiment in which the cutting insert is attached to the cutting edge portion 2 of the end mill main body 1 in this way, the shank portion 3 is gripped by the spindle of the machine tool and the end mill rotation direction T is around the axis O. While being rotated, it is sent out in a direction intersecting the axis O, and the work material is grooved or shoulder-cut.

切刃部２の外周部には、エンドミル本体１の先端に開口して後端側に延びる切屑排出溝４が、後端側に向かうに従いエンドミル回転方向Ｔとは反対側に捩れるように、周方向に間隔をあけて複数条形成されており、本実施形態では２条の切屑排出溝４が周方向に等間隔に形成されている。そして、これらの切屑排出溝４のエンドミル回転方向Ｔを向く壁面には複数のインサート取付座５が形成されていて、本実施形態では各切屑排出溝４ごとに４つのインサート取付座５が、切屑排出溝４の捩れに合わせて後端側に向かうに従いエンドミル回転方向Ｔとは反対側に向けて周方向にずらされるようにして階段状に並んで形成されている。 On the outer peripheral portion of the cutting edge portion 2, a chip discharge groove 4 that opens at the tip of the end mill body 1 and extends toward the rear end side is twisted in the direction opposite to the end mill rotation direction T toward the rear end side. A plurality of rows are formed at intervals in the circumferential direction, and in the present embodiment, two chip discharge grooves 4 are formed at equal intervals in the circumferential direction. A plurality of insert mounting seats 5 are formed on the wall surface of these chip discharge grooves 4 facing the end mill rotation direction T. In the present embodiment, four insert mounting seats 5 are formed for each chip discharge groove 4. The discharge grooves 4 are formed in a staircase pattern so as to be displaced in the circumferential direction toward the side opposite to the end mill rotation direction T toward the rear end side in accordance with the twist of the discharge groove 4.

これらのインサート取付座５は、エンドミル回転方向Ｔを向く長方形状の取付座底面５ａと、この取付座底面５ａの内周縁からエンドミル回転方向Ｔに延びてエンドミル本体１の外周側を向く取付座壁面５ｂと、最先端のインサート取付座５を除いて、取付座底面５ａの先端縁からエンドミル回転方向Ｔに延びて後端側を向く取付座壁面５ｃとを備えている。取付座底面５ａは後端側に向かうに従いエンドミル回転方向Ｔとは反対側に向かうように僅かに傾斜しており、この取付座底面５ａの中央部にはネジ孔５ｄが垂直に形成されている。 These insert mounting seats 5 have a rectangular mounting seat bottom surface 5a facing the end mill rotation direction T and a mounting seat wall surface extending from the inner peripheral edge of the mounting seat bottom surface 5a in the end mill rotation direction T and facing the outer peripheral side of the end mill body 1. Except for the state-of-the-art insert mounting seat 5, the mounting seat wall surface 5c extends from the tip edge of the mounting seat bottom surface 5a in the end mill rotation direction T and faces the rear end side. The bottom surface 5a of the mounting seat is slightly inclined so as to face the side opposite to the rotation direction T of the end mill toward the rear end side, and a screw hole 5d is vertically formed in the central portion of the bottom surface 5a of the mounting seat. ..

このようなインサート取付座５に取り付けられる切削インサート１０は、超硬合金等の硬質材料により、本実施形態では上述のように長辺と短辺を有する平行四辺形または長方形の四角形板状に形成されている。このような切削インサート１０は、一方の四角形面がエンドミル回転方向Ｔに向けられるすくい面１０ａとされて、その２つの長辺に主切刃１０ｂが形成されるとともに、２つの短辺には、主切刃１０ｂがエンドミル本体１の外周側に向けられたときに、この主切刃１０ｂのエンドミル本体１先端側に向けられるコーナ刃１０ｃに連なるように副切刃１０ｄが形成されている。なお、主切刃１０ｂは、上記コーナ刃１０ｃから離れるに従い着座面１０ｅとされる他方の四角形面に向けて延びるように傾斜している。 The cutting insert 10 attached to the insert mounting seat 5 is formed of a hard material such as cemented carbide in the shape of a parallelogram or a rectangular quadrangular plate having a long side and a short side as described above in the present embodiment. Has been done. In such a cutting insert 10, one rectangular surface is a rake surface 10a whose end mill rotation direction T is directed, and a main cutting edge 10b is formed on the two long sides thereof, and the two short sides are formed on the two short sides. When the main cutting blade 10b is directed toward the outer peripheral side of the end mill main body 1, the secondary cutting blade 10d is formed so as to be connected to the corner blade 10c directed toward the tip end side of the end mill main body 1 of the main cutting blade 10b. The main cutting edge 10b is inclined so as to extend toward the other quadrangular surface to be the seating surface 10e as the distance from the corner blade 10c increases.

また、すくい面１０ａの中央部から上記着座面１０ｅの中央部にかけては、切削インサート１０を貫通する貫通孔が形成されており、着座面１０ｅは、この貫通孔の中心線に垂直な平面状とされている。さらに、すくい面１０ａと着座面１０ｅに交差する切削インサート１０の４つの側面は逃げ面とされ、本実施形態の切削インサート１０は、この逃げ面がすくい面から離れるに従い内方に後退するように傾斜したポジティブタイプの切削インサートとされている。ここで、この逃げ面とされる側面には捩れが与えられていて、これにより着座面１０ｅがなす四角形は、図９および図１０に示すようにすくい面１０ａに対向する方向から見た透視図において、その長辺が上記コーナ刃１０ｃ側から離れるに従い該主切刃１０ｂに近づくように傾斜している。 Further, a through hole penetrating the cutting insert 10 is formed from the central portion of the rake face 10a to the central portion of the seating surface 10e, and the seating surface 10e has a flat shape perpendicular to the center line of the through hole. Has been done. Further, the four side surfaces of the cutting insert 10 intersecting the rake face 10a and the seating surface 10e are set as flanks, and the cutting insert 10 of the present embodiment retracts inward as the flanks move away from the rake face. It is said to be an inclined positive type cutting insert. Here, a twist is given to the side surface to be the flank, and the quadrangle formed by the seating surface 10e is a perspective view seen from a direction facing the rake surface 10a as shown in FIGS. 9 and 10. The long side thereof is inclined so as to approach the main cutting blade 10b as the distance from the corner blade 10c side increases.

このような切削インサート１０は、すくい面１０ａをエンドミル回転方向Ｔに向けて上記着座面１０ｅを取付座底面５ａに密着させるとともに、４つの側面のうちエンドミル本体１の内周側に向けられる側面を取付座壁面５ｂに当接させ、また最先端のインサート取付座５に取り付けられる切削インサート１０を除いてエンドミル本体１の先端側に向けられる側面を取付座壁面５ｃに当接させ、１つの主切刃１０ｂをエンドミル本体１の切刃部２の外周側に向けて突出させてインサート取付座５に着座させられ、上記貫通孔に挿通されたクランプネジ１１をネジ孔５ｄにねじ込むことによって着脱可能にエンドミル本体１に取り付けられる。 In such a cutting insert 10, the rake face 10a is directed in the end mill rotation direction T, the seating surface 10e is brought into close contact with the mounting seat bottom surface 5a, and the side surface of the four side surfaces that is directed toward the inner peripheral side of the end mill body 1 is formed. The side surface of the end mill body 1 is brought into contact with the mounting seat wall surface 5c, except for the cutting insert 10 attached to the state-of-the-art insert mounting seat 5, which is brought into contact with the mounting seat wall surface 5b. The blade 10b is projected toward the outer peripheral side of the cutting edge portion 2 of the end mill main body 1 and is seated on the insert mounting seat 5, and can be attached and detached by screwing the clamp screw 11 inserted through the through hole into the screw hole 5d. It is attached to the end mill body 1.

このようにして１つの切屑排出溝４に形成された複数のインサート取付座５に取り付けられた切削インサート１０は、互いに干渉しないようにインサート取付座５と同じく後端側に向かうに従いエンドミル回転方向Ｔとは反対側に向けて周方向にずらされることになる。このとき、これらの切削インサート１０では、その外周側に向けられた主切刃１０ｂが、図９に示されるように軸線Ｏ方向に隣接する切削インサート１０同士で、軸線Ｏ回りの回転軌跡において先端部と後端部とで部分的に重なり合って軸線Ｏを中心とする概略円筒面状をなすように配置される。 The cutting inserts 10 attached to the plurality of insert mounting seats 5 formed in one chip discharge groove 4 in this way are directed toward the rear end side like the insert mounting seats 5 so as not to interfere with each other, and the end mill rotation direction T. It will be shifted in the circumferential direction toward the opposite side. At this time, in these cutting inserts 10, the main cutting edge 10b directed to the outer peripheral side thereof is the tip of the cutting inserts 10 adjacent to each other in the axis O direction in the rotation locus around the axis O as shown in FIG. The portion and the rear end portion partially overlap each other and are arranged so as to form a substantially cylindrical surface centered on the axis O.

そして、このように軸線Ｏ方向に隣接する切削インサート１０同士で部分的に重なり合った主切刃１０ｂに対し、上記エンドミル本体１の切刃部２の外周面には、インサート取付座５からエンドミル回転方向Ｔとは反対側に向けて延びる凹溝６が形成されており、この凹溝６は、軸線Ｏ回りの回転軌跡において図９に示すように、軸線Ｏ方向に隣り合った切削インサート１０の外周側に向けられる主切刃１０ｂ同士が重なり合う部分が最深部となるように形成されている。ここで、この凹溝６の上記最深部まで深さＡは、本実施形態では０．０７ｍｍ以上とされている。 Then, with respect to the main cutting edge 10b in which the cutting inserts 10 adjacent to each other in the axis O direction partially overlap each other, the end mill rotates from the insert mounting seat 5 on the outer peripheral surface of the cutting edge portion 2 of the end mill main body 1. A concave groove 6 extending toward the side opposite to the direction T is formed, and the concave groove 6 is a cutting insert 10 adjacent to the cutting insert 10 in the axis O direction as shown in FIG. 9 in the rotation locus around the axis O. The deepest portion is formed so that the portion where the main cutting blades 10b facing the outer peripheral side overlap each other is the deepest portion. Here, the depth A to the deepest portion of the concave groove 6 is 0.07 mm or more in the present embodiment.

また、この凹溝６は、軸線Ｏに沿った断面において、上記最深部となる軸線Ｏに平行に延びる溝底面６ａと、この溝底面６ａから軸線Ｏ方向の両端側に向かうに従い互いに離れつつ外周側に延びる２つの溝壁面６ｂ、６ｃとを有する台形状に形成されている。このうち、軸線Ｏに沿った断面において、凹溝６の溝底面６ａから後端側に延びる溝壁面６ｂが溝底面６ａの後端側への延長線Ｌ１に対してなす傾斜角θ１は、凹溝６の溝底面６ａから先端側に延びる溝壁面６ｃが溝底面６ａの先端側への延長線Ｌ２に対してなす傾斜角θ２よりも小さくされており、この傾斜角θ１は４５°以下とされている。 Further, the concave groove 6 has a groove bottom surface 6a extending in parallel with the axis line O, which is the deepest portion in the cross section along the axis line O, and an outer circumference while being separated from each other from the groove bottom surface 6a toward both ends in the axis line O direction. It is formed in a trapezoidal shape having two groove wall surfaces 6b and 6c extending to the side. Of these, in the cross section along the axis O, the inclination angle θ1 formed by the groove wall surface 6b extending from the groove bottom surface 6a of the concave groove 6 to the rear end side with respect to the extension line L1 to the rear end side of the groove bottom surface 6a is concave. The groove wall surface 6c extending from the groove bottom surface 6a of the groove 6 to the tip end side is made smaller than the inclination angle θ2 formed with respect to the extension line L2 of the groove bottom surface 6a toward the tip end side, and this inclination angle θ1 is set to 45 ° or less. ing.

なお、この傾斜角θ１は、本実施形態では上述したすくい面１０ａに対向する方向から見た透視図において着座面１０ｅの外周側に向けられる長辺がコーナ刃１０ｃ側から離れるに従い主切刃１０ｂに近づくように傾斜したときの傾斜角と略等しく設定されており、従ってインサート取付座５の取付座底面５ａと凹溝６の溝壁面６ｂとの交差稜線部は、図１０に示すように着座面１０ｅの外周側に向けられる長辺に対して略平行に、僅かにエンドミル本体１の内周側に位置するように配置される。 In the present embodiment, the inclination angle θ1 is determined by the main cutting blade 10b as the long side directed toward the outer peripheral side of the seating surface 10e is separated from the corner blade 10c side in the perspective view seen from the direction facing the rake surface 10a described above. The inclination angle is set to be substantially equal to the inclination angle when the insert mounting seat 5 is tilted so as to approach, so that the intersecting ridge line portion between the mounting seat bottom surface 5a of the insert mounting seat 5 and the groove wall surface 6b of the concave groove 6 is seated as shown in FIG. It is arranged so as to be slightly parallel to the long side of the surface 10e facing the outer peripheral side and slightly on the inner peripheral side of the end mill main body 1.

また、本実施形態では、複数のインサート取付座５からエンドミル回転方向Ｔとは反対側に延びる複数の凹溝６は軸線Ｏ方向に連続しており、すなわち先端側の凹溝６の溝壁面６ｂと、その後端側に隣接する凹溝６の溝壁面６ｃとは交差している。さらに、１つの切屑排出溝４のエンドミル回転方向Ｔを向く壁面に形成されたインサート取付座５からエンドミル回転方向Ｔとは反対側に向けて延びる凹溝６は、本実施形態では一定の上記深さＡおよび断面形状で、この１つの切屑排出溝４のエンドミル回転方向Ｔとは反対側に隣接した切屑排出溝４に連通している。 Further, in the present embodiment, the plurality of concave grooves 6 extending from the plurality of insert mounting seats 5 on the side opposite to the end mill rotation direction T are continuous in the axis O direction, that is, the groove wall surface 6b of the concave groove 6 on the tip side. And the groove wall surface 6c of the concave groove 6 adjacent to the rear end side intersect. Further, the concave groove 6 extending from the insert mounting seat 5 formed on the wall surface of one chip discharge groove 4 facing the end mill rotation direction T toward the side opposite to the end mill rotation direction T has a constant depth in the present embodiment. A and the cross-sectional shape of the one chip discharge groove 4 communicate with the chip discharge groove 4 adjacent to the side opposite to the end mill rotation direction T.

このように構成されたエンドミル本体１および該エンドミル本体１に切削インサート１０を取り付けた刃先交換式エンドミルでは、上述のようにエンドミル本体１の切刃部２外周面に形成される凹溝６が、軸線Ｏ回りの回転軌跡において、軸線Ｏ方向に隣り合った切削インサート１０の外周側に向けられる主切刃１０ｂ同士が重なり合う部分が最深部となるように形成されており、エンドミル本体の振動やビビリによって針状の微細な切屑が生成された場合に、これが周方向にずらされた隣接する切削インサート１０の間を通ってエンドミル本体１の外周面に回り込んでも、この凹溝６の最深部に導いて効率的に排出することが可能となる。 In the end mill main body 1 configured as described above and the cutting edge replaceable end mill in which the cutting insert 10 is attached to the end mill main body 1, the concave groove 6 formed on the outer peripheral surface of the cutting edge portion 2 of the end mill main body 1 is formed as described above. In the rotation locus around the axis O, the portion where the main cutting blades 10b facing the outer peripheral side of the cutting inserts 10 adjacent to each other in the axis O direction overlap each other is formed to be the deepest part, and the end mill body vibrates and chatters. When needle-shaped fine chips are generated by the tool, even if they pass between adjacent cutting inserts 10 displaced in the circumferential direction and wrap around to the outer peripheral surface of the end mill main body 1, the deepest portion of the concave groove 6 is formed. It is possible to guide and efficiently discharge.

従って、上記構成のエンドミル本体１および刃先交換式エンドミルによれば、このような針状の微細な切屑が擦過することによってエンドミル本体１の切刃部２外周面に溶着するのを確実に防ぐことができ、溶着によるエンドミル本体１の破損を防止することが可能となる。なお、本実施形態では、凹溝６がエンドミル回転方向Ｔとは反対側に隣接した切屑排出溝４に連通しているので、この隣接した切屑排出溝４に微細な切屑を排出することができるが、例えば凹溝６の深さＡをエンドミル回転方向Ｔとは反対側に向かうに従い漸次浅くして、肩削り加工の際などに凹溝６が露出したときに排出されるようにしてもよい。 Therefore, according to the end mill body 1 and indexable Endomi le above configuration prevents the welding by such needle-like fine chips are scraping the cutting edge portion 2 the outer peripheral surface of the end mill body 1 securely This makes it possible to prevent damage to the end mill body 1 due to welding. In the present embodiment, since the concave groove 6 communicates with the chip discharge groove 4 adjacent to the side opposite to the end mill rotation direction T, fine chips can be discharged to the adjacent chip discharge groove 4. However, for example, the depth A of the recessed groove 6 may be gradually made shallower toward the side opposite to the end mill rotation direction T so that the recessed groove 6 is discharged when the recessed groove 6 is exposed, such as during shoulder cutting. ..

また、凹溝６の最深部である溝底面６ａまでの深さ（本実施形態では、先端側の凹溝６の溝壁面６ｂと、その後端側に隣接する凹溝６の溝壁面６ｃとの交差稜線からの深さ）Ａは、排出される切屑が針状の微細なものであるので、下限は極浅く上述のように０．０７ｍｍ以上であればよい。一方、この凹溝６の深さＡが深くなりすぎるとエンドミル本体１の剛性不足が助長されて折損を招くおそれがあるので、凹溝６の最深部である溝底面６ａまでの深さの上限は工具径（切削インサート１０の外周側に向けられる主切刃１０ｂの回転軌跡がなす上記円筒面の直径）の５％程度とされるのが望ましい。 Further, the depth to the groove bottom surface 6a, which is the deepest portion of the concave groove 6, (in the present embodiment, the groove wall surface 6b of the concave groove 6 on the tip side and the groove wall surface 6c of the concave groove 6 adjacent to the rear end side Since the chips discharged from the (depth) A from the crossed ridgeline are fine needle-shaped ones, the lower limit is extremely shallow and may be 0.07 mm or more as described above. On the other hand, if the depth A of the concave groove 6 becomes too deep, insufficient rigidity of the end mill body 1 may be promoted and breakage may occur. Therefore, the upper limit of the depth to the groove bottom surface 6a, which is the deepest part of the concave groove 6, is reached. Is preferably about 5% of the tool diameter (the diameter of the cylindrical surface formed by the rotation locus of the main cutting edge 10b directed to the outer peripheral side of the cutting insert 10).

なお、本実施形態では、上述のように複数の凹溝６が軸線Ｏ方向に隣接しており、このときの凹溝６の深さＡは、隣接する凹溝６の溝壁面６ｂ、６ｃ同士の交差稜線から最深部である溝底面６ａまでの深さとなる。また、このように凹溝６が連続せず、間にエンドミル本体１の切刃部２の円筒面状の外周面が残されている場合は、この外周面から最深部である溝底面６ａまでの深さが凹溝６の深さＡとなる。 In the present embodiment, as described above, a plurality of concave grooves 6 are adjacent to each other in the axis O direction, and the depth A of the concave grooves 6 at this time is the groove wall surfaces 6b and 6c of the adjacent concave grooves 6. It is the depth from the crossing ridgeline of the above to the deepest groove bottom surface 6a. Further, when the concave groove 6 is not continuous and a cylindrical outer peripheral surface of the cutting edge portion 2 of the end mill main body 1 is left between them, the outer peripheral surface to the deepest groove bottom surface 6a. Is the depth A of the concave groove 6.

さらに、凹溝６の断面形状は、特許文献１に記載されたような円弧状やＶ字形、Ｕ字形であってもよいが、凹溝６の断面が円弧状の場合に上述のように深さＡを浅くすると、この円弧の両端部において加工面との間隔が急に狭くなって針状の微細な切屑が噛み込まれ易くなり、やはり溶着を招くおそれがある。また、凹溝６の断面がＶ字形やＵ字形では、断面台形の凹溝６に比べて同じ断面積を確保するためには溝深さを深くしなければならなくなるおそれがあってエンドミル本体１の剛性を一層損なうことになる。さらに、Ｖ字形断面の凹溝では最深部を起点にエンドミル本体１の切刃部２に折損が生じ易くなる。 Further, the cross-sectional shape of the concave groove 6 may be an arc shape, a V shape, or a U shape as described in Patent Document 1, but when the cross section of the concave groove 6 is an arc shape, it is deep as described above. When the value A is made shallow, the distance from the machined surface is suddenly narrowed at both ends of the arc, and fine needle-shaped chips are likely to be bitten, which may also lead to welding. Further, when the cross section of the concave groove 6 is V-shaped or U-shaped, the groove depth may have to be increased in order to secure the same cross-sectional area as compared with the concave groove 6 having a trapezoidal cross section, and the end mill main body 1 The rigidity of the is further impaired. Further, in the concave groove having a V-shaped cross section, the cutting edge portion 2 of the end mill main body 1 is likely to be broken starting from the deepest portion.

これに対して、本実施形態では、凹溝６は、軸線Ｏに沿った断面において、最深部となる軸線Ｏに平行に延びる溝底面６ａと、この溝底面６ａから軸線Ｏ方向の両端側に向かうに従い互いに離れつつ外周側に延びる２つの溝壁面６ｂ、６ｃとを有する台形状に形成されているので、その軸線Ｏ方向の両端部における加工面との間隔は一定の割合で小さくなるだけであり、微細な切屑の噛み込みを生じ難い。また、断面がＶ字形やＵ字形の凹溝と比べて深さＡを浅くしても断面積を確保し易く、さらに溝底面６ａと２つの溝壁面６ｂ、６ｃとは鈍角に交差するので、その交差稜線部からエンドミル本体１に折損が生じるおそれもない。なお、溝底面６ａは、凹溝６の深さＡが深くなりすぎなければ、溝壁面６ｂ、６ｃに連なる断面凹曲線状であってもよい。 On the other hand, in the present embodiment, the concave groove 6 has a groove bottom surface 6a extending parallel to the axis line O, which is the deepest portion in the cross section along the axis line O, and both ends of the groove bottom surface 6a in the axis line O direction. Since it is formed in a trapezoidal shape having two groove wall surfaces 6b and 6c extending toward the outer peripheral side while being separated from each other as it goes toward it, the distance between the machined surfaces at both ends in the axis O direction is reduced by a constant ratio. Yes, it is difficult for fine chips to get caught. Further, it is easy to secure the cross-sectional area even if the depth A is shallower than that of the V-shaped or U-shaped concave groove, and the groove bottom surface 6a and the two groove wall surfaces 6b and 6c intersect at an obtuse angle. There is no possibility that the end mill main body 1 will be broken from the intersecting ridge line portion. The groove bottom surface 6a may have a concave curved cross section connected to the groove wall surfaces 6b and 6c as long as the depth A of the concave groove 6 is not too deep.

さらに、本実施形態では、上記切削インサート１０として長辺と短辺を有する平行四辺形または長方形の四角形板状のものが用いられ、その一方の四角形面がすくい面１０ａとしてエンドミル回転方向Ｔに向けられ、このすくい面１０ａの２つの長辺のうちの１つがエンドミル本体１の外周側に向けられて切削に使用される。このため、切り込み量を大きくする場合でも、少ない数の切削インサート１０によって対応が可能である。 Further, in the present embodiment, the cutting insert 10 is a parallelogram or a rectangular quadrangular plate having a long side and a short side, and one of the quadrangular surfaces is directed to the end mill rotation direction T as a rake surface 10a. Then, one of the two long sides of the rake face 10a is directed toward the outer peripheral side of the end mill main body 1 and used for cutting. Therefore, even when the depth of cut is increased, it is possible to deal with it by using a small number of cutting inserts 10.

ここで、切削インサート１０の他方の四角形面は、インサート取付座５のエンドミル回転方向Ｔを向く取付座底面５ａに密着する着座面１０ｅとなるが、このとき例えば凹溝６の断面形状が、溝底面６ａの長さが長くて溝壁面６ｂの上記傾斜角θ１が溝壁面６ｃの傾斜角θ２と等しい等脚台形であると、この着座面１０ｅのエンドミル本体１外周側に向けられる長辺と、インサート取付座５の取付座底面５ａと凹溝６との間隔（溝底面６ａとの間隔）が大きくなって、切削インサート１０を支持する部分が小さくなり、切削インサート１０の取付安定性が損なわれるおそれがある。 Here, the other quadrangular surface of the cutting insert 10 is a seating surface 10e that is in close contact with the bottom surface 5a of the mounting seat facing the end mill rotation direction T of the insert mounting seat 5. At this time, for example, the cross-sectional shape of the concave groove 6 is a groove. If the length of the bottom surface 6a is long and the inclination angle θ1 of the groove wall surface 6b is an isosceles trapezoid equal to the inclination angle θ2 of the groove wall surface 6c, the long side of the seating surface 10e facing the outer peripheral side of the end mill body 1 and The distance between the bottom surface 5a of the mounting seat 5 of the insert mounting seat 5 and the concave groove 6 (distance between the bottom surface 6a of the groove) becomes large, the portion supporting the cutting insert 10 becomes small, and the mounting stability of the cutting insert 10 is impaired. There is a risk.

これに対して、本実施形態では、軸線Ｏに沿った断面において、凹溝６の溝底面６ａから後端側に延びる溝壁面６ｂが溝底面６ａの後端側への延長線Ｌ１に対してなす傾斜角θ１が、凹溝６の溝底面６ａから先端側に延びる溝壁面６ｃが溝底面６ａの先端側への延長線Ｌ２に対してなす傾斜角θ２よりも小さくされている。そして、これにより、インサート取付座５の取付座底面５ａと凹溝６の後端側に延びる溝壁面６ｂとの交差稜線は、切削インサート１０の着座面１０ｅの外周側に向けられる長辺に沿う方向に延びるように形成されるので、上述のような等脚台形の断面と比べて切削インサート１０を支持する部分を大きくして取付安定性を確保することができる。 On the other hand, in the present embodiment, in the cross section along the axis O, the groove wall surface 6b extending from the groove bottom surface 6a of the concave groove 6 to the rear end side is relative to the extension line L1 to the rear end side of the groove bottom surface 6a. The inclination angle θ1 formed is smaller than the inclination angle θ2 formed by the groove wall surface 6c extending from the groove bottom surface 6a of the concave groove 6 toward the tip end side with respect to the extension line L2 of the groove bottom surface 6a toward the tip end side. As a result, the intersecting ridge line between the bottom surface 5a of the mounting seat 5 of the insert mounting seat 5 and the groove wall surface 6b extending toward the rear end side of the concave groove 6 is along the long side of the cutting insert 10 toward the outer peripheral side of the seating surface 10e. Since it is formed so as to extend in the direction, the portion supporting the cutting insert 10 can be made larger than the above-mentioned isosceles trapezoidal cross section to ensure mounting stability.

特に、本実施形態では、図９および図１０に示したように切削インサート１０をすくい面１０ａに対向する方向から見た透視図において、着座面１０ｅの外周側に向けられる長辺がコーナ刃１０ｃ側から離れるに従い主切刃１０ｂに近づくように傾斜しており、上記傾斜角θ１は、この透視図における主切刃１０ｂに対する着座面１０ｅの外周側に向けられる長辺の傾斜角と略等しく設定されている。このため、インサート取付座５の取付座底面５ａと凹溝６の溝壁面６ｂとの交差稜線部は、図１０に示したように着座面１０ｅの外周側に向けられる長辺に略平行に延びることになるので、これらの長辺と交差稜線部の間隔を小さな一定間隔として、切削インサート１０の取付安定性を一層向上させることができる。 In particular, in the present embodiment, as shown in FIGS. 9 and 10, in the perspective view of the cutting insert 10 viewed from the direction facing the rake face 10a, the long side facing the outer peripheral side of the seating surface 10e is the corner blade 10c. The inclination angle θ1 is set so as to approach the main cutting edge 10b as the distance from the side increases, and the inclination angle θ1 is set to be substantially equal to the inclination angle of the long side of the seating surface 10e with respect to the main cutting edge 10b in this perspective view. Has been done. Therefore, the intersecting ridge line portion between the bottom surface 5a of the mounting seat 5 of the insert mounting seat 5 and the groove wall surface 6b of the concave groove 6 extends substantially parallel to the long side facing the outer peripheral side of the seating surface 10e as shown in FIG. Therefore, the mounting stability of the cutting insert 10 can be further improved by setting the distance between these long sides and the intersecting ridges to a small constant distance.

さらに、本実施形態では、上記傾斜角θ１が４５°以下とされていて、軸線Ｏに沿った断面における凹溝６の溝底面６ａと溝壁面６ｂとの交差角は１３５°以上の鈍角となる。このため、これら凹溝６の溝底面６ａと溝壁面６ｂとの交差稜線部に切削抵抗による応力が集中するのを防ぐことができ、この交差稜線部を起点としてエンドミル本体１の切刃部２に折損が生じるのも確実に防止することができる。なお、傾斜角θ２についても４５°以下とされるのが望ましい。 Further, in the present embodiment, the inclination angle θ1 is 45 ° or less, and the intersection angle between the groove bottom surface 6a of the concave groove 6 and the groove wall surface 6b in the cross section along the axis O is an obtuse angle of 135 ° or more. .. Therefore, it is possible to prevent stress due to cutting resistance from concentrating on the intersecting ridge line portion between the groove bottom surface 6a and the groove wall surface 6b of the concave groove 6, and the cutting edge portion 2 of the end mill main body 1 starts from this intersecting ridge line portion. It is possible to surely prevent the breakage of the blade. It is desirable that the inclination angle θ2 is also 45 ° or less.

１ エンドミル本体
２ 切刃部
３ シャンク部
４ 切屑排出溝
５ インサート取付座
５ａ 取付座底面
５ｂ、５ｃ 取付座壁面
６ 凹溝
６ａ 溝底面
６ｂ、６ｃ 溝壁面
１０ 切削インサート
１０ａ すくい面
１０ｂ 主切刃（エンドミル本体１の外周側に向けられる切刃）
１０ｅ 着座面
Ｏ エンドミル本体１の軸線
Ｔ エンドミル回転方向
Ａ 凹溝６の深さ
θ１ 軸線Ｏに沿った断面において、凹溝６の溝底面６ａから後端側に延びる溝壁面６ｂが溝底面６ａの後端側への延長線Ｌ１に対してなす傾斜角
θ２ 軸線Ｏに沿った断面において、凹溝６の溝底面６ａから先端側に延びる溝壁面６ｃが溝底面６ａの先端側への延長線Ｌ２に対してなす傾斜角 1 End mill body 2 Cutting edge part 3 Shank part 4 Chip discharge groove 5 Insert mounting seat 5a Mounting seat bottom surface 5b, 5c Mounting seat wall surface 6 Concave groove 6a Groove bottom surface 6b, 6c Groove wall surface 10 Cutting insert 10a Scooping surface 10b Main cutting edge Cutting edge directed toward the outer peripheral side of the end mill body 1)
10e Seating surface O Axis of end mill body 1 T End mill rotation direction A Depth of concave groove 6 θ1 In the cross section along the axis O, the groove wall surface 6b extending from the groove bottom surface 6a of the recessed groove 6 to the rear end side is the groove bottom surface 6a. Inclination angle θ2 with respect to the extension line L1 to the rear end side In the cross section along the axis O, the groove wall surface 6c extending from the groove bottom surface 6a of the concave groove 6 to the tip end side is an extension line L2 to the tip end side of the groove bottom surface 6a. Tilt angle with respect to

Claims (5)

軸線を中心とした円柱状をなして上記軸線回りにエンドミル回転方向に回転させられ、先端外周部に形成されたインサート取付座に着脱可能に取り付けられる切削インサートの外周側に向けられる切刃によって切削加工を行う刃先交換式エンドミルのエンドミル本体であって、
このエンドミル本体の先端外周部には、該エンドミル本体の先端から後端側に延びる切屑排出溝が形成されるとともに、この切屑排出溝のエンドミル回転方向を向く壁面に複数の上記インサート取付座が上記軸線方向に並んで形成されていて、
これらのインサート取付座に取り付けられる上記切削インサートは周方向にずらされるとともに、外周側に向けられる上記切刃の上記軸線回りの回転軌跡が部分的に重なり合って上記軸線方向に連続し、
上記エンドミル本体の外周面には、上記インサート取付座からエンドミル回転方向とは反対側に向けて延びる凹溝が形成され、
この凹溝は、上記軸線回りの回転軌跡において、上記軸線方向に隣り合った上記切削インサートの外周側に向けられる上記切刃同士が重なり合う部分が最深部となるように形成され、
上記凹溝は、上記軸線に沿った断面において、上記最深部となる上記軸線に平行に延びる溝底面と、この溝底面から上記軸線方向の両端側に向かうに従い互いに離れつつ外周側に延びる２つの溝壁面とを有する台形状に形成されていることを特徴とする刃先交換式エンドミルのエンドミル本体。 A cutting blade that forms a columnar shape centered on the axis, is rotated in the end mill rotation direction around the axis, and is detachably attached to the insert mounting seat formed on the outer peripheral portion of the tip. It is the end mill body of the end mill with replaceable cutting edge for processing.
A chip discharge groove extending from the tip of the end mill body to the rear end side is formed on the outer peripheral portion of the tip of the end mill body, and a plurality of the insert mounting seats are provided on the wall surface of the chip discharge groove facing the end mill rotation direction. It is formed side by side in the axial direction,
The cutting inserts attached to these insert mounting seats are shifted in the circumferential direction, and the rotation loci of the cutting edge directed to the outer peripheral side around the axis partially overlap and are continuous in the axis direction.
A concave groove extending from the insert mounting seat in the direction opposite to the rotation direction of the end mill is formed on the outer peripheral surface of the end mill body.
The concave groove is formed so that the deepest portion of the rotation locus around the axis is the portion where the cutting blades facing the outer peripheral side of the cutting inserts adjacent to each other in the axis direction overlap each other .
The concave groove has a groove bottom surface extending parallel to the axis line, which is the deepest part in the cross section along the axis line, and two groove bottom surfaces extending toward the outer peripheral side while being separated from each other toward both ends in the axial direction. The end mill body of an end mill with a replaceable cutting edge, which is formed in a trapezoidal shape having a groove wall surface. 上記凹溝の上記最深部まで深さが０．０７ｍｍ以上であることを特徴とする請求項１に記載の刃先交換式エンドミルのエンドミル本体。 The end mill main body of the end mill with a replaceable cutting edge according to claim 1, wherein the depth to the deepest portion of the concave groove is 0.07 mm or more. 上記軸線に沿った断面において、上記凹溝の溝底面から後端側に延びる上記溝壁面が該溝底面の後端側への延長線に対してなす傾斜角は、上記凹溝の溝底面から先端側に延びる上記溝壁面が該溝底面の先端側への延長線に対してなす傾斜角よりも小さくされていることを特徴とする請求項１または請求項２に記載の刃先交換式エンドミルのエンドミル本体。 In the cross section along the axis, the inclination angle formed by the groove wall surface extending from the groove bottom surface of the concave groove to the rear end side with respect to the extension line to the rear end side of the groove bottom surface is from the groove bottom surface of the concave groove. The cutting edge replaceable end mill according to claim 1 or 2 , wherein the groove wall surface extending to the tip side is made smaller than the inclination angle formed with respect to the extension line of the groove bottom surface to the tip side. End mill body. 上記軸線に沿った断面において、上記凹溝の溝底面から後端側に延びる上記溝壁面が上記凹溝の溝底面の後端側への延長線に対してなす傾斜角が４５°以下とされていることを特徴とする請求項１から請求項３のうちいずれか一項に記載の刃先交換式エンドミルのエンドミル本体。 In the cross section along the axis, the inclination angle formed by the groove wall surface extending from the groove bottom surface of the concave groove to the rear end side with respect to the extension line of the groove bottom surface to the rear end side of the concave groove is 45 ° or less. The end mill main body of the end mill with a replaceable cutting edge according to any one of claims 1 to 3, wherein the end mill body is characterized by the above. 請求項１から請求項４のうちいずれか一項に記載の刃先交換式エンドミルのエンドミル本体における上記インサート取付座に、上記切削インサートが、外周側に向けられる上記切刃の上記軸線回りの回転軌跡が部分的に重なり合って上記軸線方向に連続するように着脱可能に取り付けられていることを特徴とする刃先交換式エンドミル。 A rotation locus around the axis of the cutting edge in which the cutting insert is directed toward the outer peripheral side on the insert mounting seat in the end mill main body of the blade tip exchange type end mill according to any one of claims 1 to 4. An end mill with a replaceable cutting edge, characterized in that the blades are partially overlapped and detachably attached so as to be continuous in the axial direction.
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