JP3668011B2 - Drill insert and throw-away drill using the same - Google Patents

Description

【００３５】

そして、穴壁面にツールマークが発生するかどうか並びに穴底面にヘソマークが発生するかどうかを観察した。なお一般的に、内刃インサートが芯高となっている場合にヘソマークは付かず、これに対して、適性芯高さの場合にヘソマークは発生する。したがって、表中、ツールマークが無い場合を○記号、有る場合を×記号にするのに対して、ヘソマークが有る場合を○記号、無い場合を×記号として印す。この実験結果を表１にまとめた。
【００３６】
表１から明らかなように、試料番号１は第一切刃のすくい角が過大で、第二切刃のすくい角が過少であり、そのため、内刃が芯高となりツールマークも発生してしまった。
【００３７】
試料番号２は、第二切刃のすくい角が過少であり、そのため、内刃インサートが芯高となりツールマークも発生してしまった。
【００３８】
試料番号７は、ツールマークが発生しなかったが内刃インサートの切屑処理が悪く、切削抵抗が増大していた。なお、ツールマークは付いていたが、第一切刃のランド幅が過大であったためそのマークサイズが過大であった。
【００３９】
試料番号８は、第一切刃のランド幅が過大でヘソマークが発生しなかった。他方、ツールマークも発生しなかったが切削抵抗が増大していた。
【００４０】
試料番号９は、第二切刃のすくい角が過大であり、第二切刃にチッピングが発生してしまった。
【００４１】
試料番号１０は、ツールマークが発生しなかったが内刃インサートの切屑処理が悪く、切削抵抗が増大していた。なお、ツールマークは付いていたが、第一切刃のすくい角が過少であったためそのマークサイズが過大であった。
【００４２】
これに対して本発明の範囲内である試料番号３、４、５、６はいずれも良好な結果となった。
【００４３】
【発明の効果】
叙上のように本発明は、内刃インサート、外刃インサートのラジアル荷重の合成力の方向が、工具本体の中心軸から外刃インサート側になり、これによりワークからドリル工具を抜く際に外刃インサートと穴壁とが接触したりせず、良好な仕上げ面に加工することができるという優れた効果を奏し、特に外刃インサートと内刃インサートにおいて穴底面を加工する切刃のすくい角およびランド幅を違えることにより外刃インサートと内刃インサートの切削抵抗のバランスを更に微調整したので、Ｌ／Ｄを非常に大きくした場合でも、内刃インサートが芯上がりになる方向にホルダが撓む傾向を押さえ、良好な仕上げ面に加工する。
【００４４】
さらに、切屑を巾細且つ短めに切断するので、最適な切屑処理が達成するという効果を併せ持つ。
【図面の簡単な説明】
【図１】本実施形態のドリルインサートの平面図である。
【図２】（ａ）（ｂ）はともに図１のドリルインサートの部分断面図であり、（ａ）はＣーＣ線断面図、（ｂ）はＡ−Ａ線断面図である。
【図３】図１のドリルインサートをホルダーに装着した本実施形態のスローアウェイドリルにおけるインサートの側面配置図である。
【図４】図３のスローアウェイドリルにおけるインサートの底面配置図である。
【図５】従来のドリルインサートおよびスローアウェイドリルの構成を示すの形状と配置を示す図であり、（ａ）はスローアウェイドリルのドリルインサートのみの側面配置図、（ｂ）は底面配置図である。
【図６】従来の別スローアウェイドリルにおけるインサートの側面配置図である。
【符号の説明】
１ ドリルインサート
２ 上面
３ 第一切刃
４、５ コーナーＲ部
６ 突出部
７ 外刃インサート
８ 内刃インサート
９ 第二切刃
１０ 全周ブレーカー溝
１１ ランド
Ｔ スローアウェイドリル
Ｔ１ 中心軸
Ｔ２ 側面
Ｎ 合成力方向[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a drill insert for drilling holes and a throw-away drill using the same.
[0002]
[Prior art]
As a drill tool for drilling holes, a tool in which an outer diameter outer blade insert and an inner diameter inner blade insert are detachably mounted so that mutual rotation trajectories cross at the tip of the tool body has been used. .
[0003]
FIG. 5 shows a conventional drill insert 10 used in such a drill tool and an arrangement when the drill insert 10 is mounted on a drill tool body T. FIG.
[0004]
This drill insert 10 is a polygonal plate-like body, and shows one in which a cutting edge is formed on the ridge side portion of the upper surface 11, and two pieces are provided on the tool body T of one throw-away drill as shown in the same figure. The outer blade insert 12 and the inner blade insert 13 are mounted with the upper surfaces 11 and 11 facing in the same rotational direction, respectively. Further, among the cutting blades formed on the outer blade insert 12 and the inner blade insert 13, the rotation trajectory of the cutting blade that becomes the bottom cutting blade 15 intersects, and covers from the center axis T 1 to the side surface T 2 of the tool body T. To do.
[0005]
FIG. 5B shows a combined force N of radial load forces generated in each of the outer blade insert 12 and the inner blade insert 13 when cutting is performed by a throw-away drill equipped with the drill insert 10. As shown in the figure, in the conventional drill insert 10, the radial load applied to the inner blade insert 13 is generated from the central axis T1 along the bottom cutting edge 15 of the inner blade insert 13, whereas the outer blade insert 13 12 is generated in the reverse rotation direction (+ direction) based on the radius connecting the corner R portion 14 and the center axis T1 of the tool body T due to the cutting resistance received by the corner R portion 14 cutting the outer wall.
[0006]
As a result, the resultant force N of the radial load force is deflected in the direction of the inner blade insert 13, that is, in a direction in which the hole diameter is reduced during processing, and when the drill tool is removed from the workpiece, the outer blade insert 12 If it comes in contact with the wall and damages the finished surface, and the corner R portion 14 of the outer blade insert 12 hits the wall strongly when fast-feeding out, the corner R portion of the outer blade insert 12 increases when it comes off by cutting feed. There was a possibility that the damage of 14 will become large.
[0007]
Therefore, the present inventor previously protruded the protruding portion 6 having a pair of corner R portions 4 and 5 at the corner portion of the cutting edge that cuts the bottom surface in the outer blade insert 7 as shown in FIG. By adjusting the cutting resistance balance between the outer blade insert 7 and the inner blade insert 8, the outer blade insert 7 and the hole wall do not come into contact with each other when the drill tool T (throw away drill) is pulled out from the workpiece. Developed and commercialized a throw-away drill that can be machined to a good finished surface.
[0008]
[Problems to be solved by the invention]
The prior art shown in FIG. 6 shows a very excellent processing performance with a normal L / D holder. However, since the resistance of the outer blade is considerably larger than that of the inner blade, when the L / D is made very large, the holder tends to bend in the direction in which the inner blade insert rises to the center. There was a risk of damage to the holder and tool marks due to chipping or reduction of the machining diameter.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventor has conducted earnest research and cuts the outer blade insert and the inner blade insert by changing the rake angle and the land width of the cutting edge for machining the bottom surface of the hole in the outer blade insert and the inner blade insert. It has been found that the above problem can be effectively solved by finely adjusting the balance of resistance.
[0010]
That is, the present invention provides an outer side provided with a second cutting edge that cuts the bottom surface on the outer diameter side with a rake angle of 20 ° to 30 ° and a land width of 0.1 mm or less at the tip of a cylindrical tool body. A blade insert, and an inner blade insert having a rake angle of 5 ° to 13 °, a land width of not less than the land width of the second cutting blade and not more than 0.2 mm, and a first blade for cutting the bottom surface on the inner diameter side; It is an object of the present invention to provide a throw-away drill that is detachably mounted so that both rotation trajectories intersect .
[0011]
The present invention also provides a drill insert that can be used as an inner blade insert or an outer blade insert of such a throw-away drill.
[0012]
[Action]
The drill insert according to the present invention is such that a protrusion having a pair of corner R portions (4) and (5) is formed at a polygonal corner, and the protrusion is a hole at the tip of the tool body. By using it as an outer blade insert on the outer diameter side so as to face the bottom side, the radial load direction of the outer blade insert is directed to the rotation direction side (-direction), so that the resultant force direction is changed from the central axis to the outer blade. Head toward the insert side.
[0013]
Therefore, the tool body is bent toward the outer blade insert, and as a result, the machining diameter is increased. Therefore, when pulling out the throw-away drill from the machining hole, the drill tool can be pulled out of the workpiece without the outer blade insert and the hole wall contacting each other.
[0014]
In particular, according to the present invention, the cutting force of the outer blade insert can be reduced by setting the rake angle of the used cutting blade facing the bottom surface of the hole to 20 ° to 30 ° and the land width to 0.1 mm or less. Adjust in the direction to decrease, and on the other hand, use the inner blade insert facing the bottom of the hole The rake angle of the cutting blade is 5 ° to 13 ° and the land width is not less than the outer blade insert and not more than 0.2 mm Thus, the cutting force of the outer blade insert was adjusted to increase. Thereby, when L / D is made very large, there exists an effect | action which suppresses the tendency for a holder to bend in the direction in which an inner blade insert goes up.
[0015]
Further, as another action of the drill insert of the present invention and the throw-away drill using the drill insert, the inner corner R portion of the corner R portion constituting the protruding portion of the outer blade insert facing the hole bottom side is the hole bottom. Since the chip from the side is divided, the chip on the outer blade insert side is formed with a narrow width, but the cross-sectional shape in the width direction of the chip is curved by the protrusion formed close to the cutting blade of the corner R portion Formed. As a result, even if the width is narrow, the chips are cut short.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0017]
FIG. 1 shows a drill insert 1 according to the present embodiment. This drill insert 1 has a polygonal shape, and cutting edges are formed on the ridges of the upper surface 2. Of these cutting edges, a point with respect to the center axis of the insert is shown. Two sides having a symmetrical relationship are formed in a U-shape as the first blade 3, and the remaining two sides are second cutting blades, each having one pair, that is, a corner portion of the polygon. The corner R portions 4 and 5 are formed, and a protruding portion 6 slightly protruding outward is formed.
[0018]
Here, the corner R portions 4 and 5 refer to those in the range of 60 ° to 105 ° in which the angle formed by the straight line continuous to the curved portion is close to a right angle.
[0019]
Further, along the cutting edge at the edge of the upper surface 2, an R-grooved all-round breaker groove 10 is formed inside the land 11. The rake angle and land between the first cutting edge and the second cutting edge are as follows. The width is different. That is, as shown in FIG. 2B, the second cutting edge 9 has a rake angle α2 of 20 ° to 30 ° and a land width W2 of 0.1 mm or less. On the other hand, the rake angle α1 of the first blade 3 is set to 5 ° to 13 ° and the land width W1 is set to be equal to or larger than the land width W2 of the second cutting blade 9 as shown in FIG.
[0020]
Next, FIG. 3 and FIG. 4 show the arrangement of the inserts in the throw-away drill T of this embodiment equipped with the drill insert 1. FIG. 3 is a perspective view seen from the side of the side T2, and FIG. 4 is a view seen from the bottom side of the holder. In FIG. 3, the outer blade insert 7 indicated by the dotted line is for indicating the relationship between the locus of the outer blade insert 7 and the locus of the inner blade insert 8, and the position where the outer blade insert 7 indicated by the solid line is rotated by 180 °. Is shown.
[0021]
As shown in these drawings, two drill inserts 1 having the same shape are mounted on one holder as an outer blade insert 7 and an inner blade insert 8, and both upper surfaces 2 are mounted in the same rotational direction. That is, as shown in FIG. 4, the upper surface 2 of the outer blade insert 7 and the upper surface 2 of the inner blade insert 8 are oriented in the opposite direction of 180 °. And it installs so that the rotation locus | trajectory of the bottom cutting edge 9 may intersect and it may cover from the center axis | shaft T1 of the holder of the throwaway drill T to the side surface T2.
[0022]
At that time, as the outer blade insert 7, the first blade 3 is mounted on the side surface T 2, and the second cutting blade is mounted so that the protruding portion 6 is on the hole bottom outer end side. The first blade 3 is mounted with the blade 3 facing toward the bottom of the hole.
[0023]
In FIG. 4, the straight arrows indicate the radial load force applied to the outer blade insert 7 and the radial load applied to the inner blade insert 8 during the cutting process for the drill insert 1 installed as the upper blade insert 7 and the inner blade insert 8. The direction of the resultant force (the resultant force direction N) as the sum of forces is shown. As shown in FIG. ) Occurs.
[0024]
The throw-away drill T configured as described above is configured such that the protrusion 6 having a pair of corner R portions 4 and 5 is disposed on the outer bottom end side of the outer blade insert 7, so The direction of the load is directed to the rotational direction side (− direction), and thus the resultant force direction N is directed from the central axis T1 to the outer blade insert 7 side. Therefore, the holder of the throw-away drill T bends toward the outer blade insert 7 side. As a result, the throw-away drill T can be pulled out from the workpiece without the outer blade insert 7 and the hole wall contacting each other.
[0025]
Further, according to the above throwaway drill T, the outer blade insert 7 and the inner blade insert 8 can be adjusted by changing the rake angle and land width of the cutting edges (second cutting edge, first cutting edge) for machining the bottom surface of the hole. The balance of cutting resistance between the blade insert 7 and the inner blade insert 8 is further finely adjusted, and when the L / D is very large, the tendency of the holder to bend in the direction in which the inner blade insert 8 rises to the center is suppressed. It is configured as follows.
[0026]
In other words, the rake angle α2 of the used cutting edge (second cutting edge 9) of the outer blade insert 7 facing the bottom of the hole is set to 20 ° to 30 ° and the land width W2 is set to 0.1 mm or less. The cutting force of the insert 7 is adjusted to decrease, and on the other hand, the rake angle α1 of the used cutting edge (first blade 3) of the inner blade insert 8 facing the hole bottom is set to 5 ° to 13 ° and the land width By adjusting W1 to be equal to or greater than outer blade insert 7 and equal to or less than 0.2 mm, the cutting resistance of outer blade insert 7 was adjusted to increase. This is because when the L / D is very large, the holder tends to bend in the direction in which the inner blade insert 8 is raised.
[0027]
Further, as another action of the throw-away drill T of the present invention, the corner R portions 4 and 5 constituting the protruding portion 6 of the outer blade insert 7 facing the hole bottom side are continuous with the first blade. No inner corner R portion 5 cuts chips from the hole bottom side.
[0028]
When the rake angle α2 of the used cutting edge (second cutting edge 9) of the outer blade insert 7 is less than 20 °, the effect of reducing the cutting resistance of the outer blade insert 7 is insufficient, and on the other hand, it exceeds 30 °. There is a risk that the cutting edge strength will be insufficient.
[0029]
In addition, when the rake angle α1 of the used cutting edge (first blade 3) of the inner blade insert 8 is less than 5 °, there are problems such as an increase in cutting resistance, poor sharpness and easy welding.
[0030]
When the land width W2 of the used cutting edge (second cutting edge 9) of the outer blade insert 7 is larger than 0.1 mm, the effect of reducing the cutting resistance of the outer blade insert 7 is insufficient. When the land width W1 of the used cutting edge (the first cutting edge 3) is larger than 0.2 mm, there are problems such as an increase in cutting resistance, poor sharpness, and easy welding. Furthermore, when the land width W2 of the used cutting edge (second cutting edge 9) of the outer blade insert 7 is larger than the land width W1 of the used cutting edge (first blade 3) of the inner blade insert 8, the outer blade insert 7 The effect of reducing the cutting resistance is insufficient.
[0031]
As mentioned above, although embodiment of this invention was illustrated with the figure, this invention is not limited to the said embodiment, As long as it does not deviate from the objective of invention, it can be set as arbitrary forms. For example, the outline shape of the drill insert 1 may be a polygonal shape other than a quadrangle, and the shapes of the outer blade insert and the inner blade insert may be different.
[0032]
[Experimental example]
Hereinafter, experimental examples of the present invention will be described.
[0033]
For the throw-away drill T of FIG. 3 using the drill insert 1 of FIG. 1, the rake angles and land widths of the first and second cutting edges of the drill insert 1 are set as shown in Table 1, respectively. Cutting was performed under conditions.
[0034]
[Table 1]

[0035]

Then, it was observed whether or not a tool mark was generated on the hole wall surface and whether or not a chin mark was generated on the bottom surface of the hole. In general, when the inner blade insert has a core height, the tick mark is not attached, whereas, when the inner blade insert has an appropriate core height, the thigh mark is generated. Therefore, in the table, when there is no tool mark, it is marked as ◯ symbol, and when it is present, it is marked as X symbol, whereas when there is a chin mark, it is marked as ○ symbol, and when there is no tool mark, it is marked as X symbol. The results of this experiment are summarized in Table 1.
[0036]
As is clear from Table 1, sample No. 1 has an excessively rake angle for the first blade and an excessively rake angle for the second blade, so that the inner blade becomes the core height and tool marks are generated. It was.
[0037]
In Sample No. 2, the rake angle of the second cutting edge was too small, so that the inner blade insert became a core height and a tool mark was also generated.
[0038]
In Sample No. 7, no tool mark was generated, but the chip treatment of the inner blade insert was poor, and the cutting resistance was increased. Although the tool mark was attached, the mark size was excessive because the land width of the first blade was excessive.
[0039]
In sample No. 8, the land width of the first blade was too large and no tick marks were generated. On the other hand, no tool mark was generated, but the cutting resistance increased.
[0040]
In sample number 9, the rake angle of the second cutting edge was excessive, and chipping occurred on the second cutting edge.
[0041]
In Sample No. 10, no tool mark was generated, but the chip treatment of the inner blade insert was poor, and the cutting resistance was increased. Although the tool mark was attached, the mark size was excessive because the rake angle of the first blade was too small.
[0042]
On the other hand, sample numbers 3, 4, 5, and 6 within the scope of the present invention all gave good results.
[0043]
【The invention's effect】
As described above, in the present invention, the direction of the combined force of the radial load of the inner blade insert and the outer blade insert is from the center axis of the tool body to the outer blade insert side. The blade insert and the hole wall do not come into contact with each other and have an excellent effect of being able to be machined into a good finished surface. Especially, the rake angle of the cutting edge for machining the bottom of the hole in the outer blade insert and the inner blade insert and Since the balance of cutting resistance between the outer blade insert and the inner blade insert is further finely adjusted by changing the land width, the holder bends in the direction in which the inner blade insert rises even when L / D is very large. Suppress the trend and process to a good finished surface.
[0044]
Furthermore, since the chips are cut narrowly and shortly, it has the effect of achieving optimum chip treatment.
[Brief description of the drawings]
FIG. 1 is a plan view of a drill insert according to an embodiment.
2A and 2B are partial cross-sectional views of the drill insert of FIG. 1, FIG. 2A is a cross-sectional view taken along the line CC, and FIG. 2B is a cross-sectional view taken along the line AA.
3 is a side view of the insert in the throw-away drill of the present embodiment in which the drill insert of FIG. 1 is mounted on a holder. FIG.
4 is a bottom plan view of an insert in the throw-away drill of FIG. 3. FIG.
5A and 5B are diagrams showing the configuration and arrangement of a conventional drill insert and a throwaway drill, wherein FIG. 5A is a side arrangement view of only the throw insert of the throwaway drill, and FIG. 5B is a bottom arrangement view. is there.
FIG. 6 is a side view of an insert in another conventional throw-away drill.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Drill insert 2 Upper surface 3 First all blades 4, 5 Corner R part 6 Protruding part 7 Outer blade insert 8 Inner blade insert 9 Second cutting blade 10 Whole circumference breaker groove 11 Land T Throw away drill T1 Center axis T2 Side surface N Composite Force direction

Claims (2)

A first blade for cutting the bottom surface on the inner diameter side when used as an inner blade insert at the edge of a polygonal plate-like body, a pair adjacent to the first blade and a corner portion of the polygon In the drill insert comprising a protruding portion having a corner R portion (4) and (5), and a second cutting blade for cutting the bottom surface on the outer diameter side for use as an outer blade insert , the second cutting blade The rake angle is 20 ° to 30 ° and the land width is 0.1 mm or less, the rake angle of the first blade is 5 ° to 13 °, and the land width is equal to or larger than the land width of the second cutting blade. Drill insert characterized by being 0.2 mm or less . An outer blade insert having a second cutting edge for cutting the bottom surface on the outer diameter side with a rake angle of 20 ° to 30 ° and a land width of 0.1 mm or less at the tip of the cylindrical tool body, and a rake angle An inner blade insert having a first blade that cuts the bottom surface on the inner diameter side with a land width of not less than 5 ° to 13 ° and a land width of not less than the land width of the second cutting blade and not more than 0.2 mm. A throw-away drill mounted so that both rotation trajectories intersect.

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