JP4369593B2 - Throw-away drill - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a throw-away drill used for drilling.
[0002]
[Prior art and issues]
As a drill used for drilling, in addition to a normal solid type drill that is integrally formed as a whole, a cutting blade is formed on the drill body (holder) and a separate throw-away tip and drilled. There is a so-called throw-away type drill that can be detachably attached to the tip of the main body with a screw or the like.
[0003]
This throw-away type drill is classified into a two-chip type and a one-chip type. Among these, the former two-chip type throw-away type drill is described in, for example, Japanese Patent Laid-Open No. 10-29108. As described above, two tips, that is, a tip having an inner blade that cuts the central portion of the hole and a tip having an outer blade that cuts the peripheral portion of the hole are mounted on the tip of the drill body. In the invention described in the above publication, both the inner blade and the outer blade are formed on one tip, and the same tip can be used as the inner blade tip or the outer blade tip depending on the orientation and position of mounting on the drill body. It is also configured.
[0004]
However, although this two-chip type configuration is suitable for a large drill having a large machining diameter, for example, if this is applied to a small drill having a machining diameter smaller than about φ10, a tip is inserted at the tip of the drill body. There is a problem that sufficient space for mounting or chip discharge cannot be secured, or the screws for chip mounting are very small and sufficient mounting strength cannot be obtained. It was.
[0005]
On the other hand, the one-chip type throw-away drill (hereinafter referred to as “one-chip drill”) is similar to the tip shape of a conventional solid-type drill as described in, for example, Japanese Patent Laid-Open No. 10-328918. In general, a chip using a pair of tips having a long edge over the entire length of the radius of the processing hole, which extends in the drilling direction and extends from the top located on the rotation axis of the drill to both sides, is generally used.
[0006]
However, since the cutting force applied to the tip during drilling is large in the above-described tip shape, it is necessary to firmly fix one tip to the tip of the drill body with two screws as shown in the drawing of the above publication. In addition, there is a problem that it is not easy to secure a space for chip discharge correspondingly because it is necessary to increase the thickness of the chip.
[0007]
Therefore, the inventor first determines the inner blade for cutting the center portion of the hole and the outer blade for cutting the peripheral edge portion of the hole, and the inner blade of the inner blade tip and the outer blade tip of the two-chip type throwaway drill. A one-chip type throw-away tip similar to a two-chip type formed on a single chip in the same arrangement as the outer cutter has been developed (Japanese Patent Laid-Open No. 11-188518).
[0008]
In the one-chip type throw-away tip similar to the above-mentioned two tips (hereinafter abbreviated as “similar one-chip”), the inner blade only needs to have a length sufficient to cut the center of the hole, and the outer blade also has Since it suffices to have a length sufficient to cut the peripheral edge of the hole, it is possible to reduce the cutting resistance applied to the chip during drilling compared to the conventional one-chip drill, and the inner and outer blades It became possible to secure a space for chip discharge by reducing the thickness of the part and using one screw for attaching to the drill body.
[0009]
As a result of further investigation of the similar one chip and its drill body, the inventor has found that the structure described in the above publication has room for further improvement, particularly in terms of chip discharge.
[0010]
An object of the present invention is to provide a novel throw-away drill that is related to the similar one chip and has improved chip discharging performance as compared with the conventional chip.
[0011]
[Means for Solving the Problems and Effects of the Invention]
To solve the above problems, indexable drill according to claim 1 of the present invention, a throw-away comprising a first block whose inner edge is formed at the front end, and a second block outer cutter formed at the front end a chip, a throw-away drill and a drill body that Ru provided with a pair of holding pieces for clamping the cutting insert, the first block is part notch at a rear end corner portion is formed, An inner blade side flute groove for discharging chips from the inner blade and an outer blade side flute groove for discharging chips from the outer blade are formed on the peripheral surface of the drill body, the drill The main body includes a liquid passing pipe that penetrates in the axial direction and reaches one of the holding pieces, and a liquid passing groove that communicates with the liquid passing pipe and is provided on a holding surface of the holding piece. part of them overlap each other and the cut-out portion And wherein the door.
[0012]
According to this configuration, the first block is provided with a notch, and the structure in which the coolant flows in the notch is used in the drill, so that the coolant can be used as an internal channel for discharging chips by using the notch as a liquid passage. It can be discharged into the flute groove on the blade side. Then, by discharging the cooling liquid into the inner blade side flute groove, it is possible to reliably discharge chips from the inner blade that are formed in an umbrella shape and are not so good in discharging performance from the hole.
[0014]
According to this configuration, the coolant can be reliably discharged into the flute groove on the inner blade side through the notch, and the liquid passage groove provided on the clamping surface of the clamping piece can also be used, for example, at the tip of the clamping piece. At the same time, the cooling holes can be discharged.
[0015]
The invention of claim 2 is the invention of claim 1, wherein the cross-sectional shape before Symbol inner blade side flutes grooves is two arcuate.
[0016]
According to this configuration, chips from the inner blade that are formed in an umbrella shape and are not so good in dischargeability fit gently into either one of the arcs, and the drill body sway in the radial direction is small and discharged. Therefore, it becomes possible to make it difficult for clogging of chips to occur.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described with reference to the accompanying drawings.
[0018]
1A and 1B are exploded perspective views of a throw-away tip and a drill main body to which the throw-away tip according to one embodiment of the present invention is attached, and FIG. 1A is an exploded perspective view seen from the front side of the tip. FIG. 1B is an exploded perspective view seen from the back side of the chip.
[0019]
With reference to these drawings, the throw-away tip 1 forms an inner blade 11 that cuts the center portion of the hole and an outer blade 12 that cuts the peripheral portion of the hole at the front end in the drilling direction. The throw-away tip 1 is formed by integrally forming a plate-like first block 13 that forms the inner blade 11 and a plate-like second block 14 that forms the outer blade 12.
[0020]
The first block 13 and the second block 14 are shaped so as to be shifted from each other in the plate surface direction, leaving a portion 15 that overlaps each other. A through-hole 1a that penetrates in the plate thickness direction at the overlapping portion 15 is formed. This through hole 1a is for inserting an attachment screw 3 for attaching the tip 1 to the drill body 2.
[0021]
The chip 1 has a first seat surface 1b and a second seat surface 1c as a pair of sandwiched surfaces on two surfaces back to back (that is, corresponding to the outer surfaces of the corner blocks 13 and 14). The through hole 1a is open to the first and second seat surfaces 1b and 1c.
[0022]
Referring to FIG. 2 , the tip 1 includes a rear seat surface 1 d received by the bottom of a pocket 23 provided at the rear portion of the drill body 2 in the drilling direction.
Further, the tip 1 has a notch portion 1g continuous between the pair of sandwiched seat surfaces 1b and 1c at the rear end corner portion of the first block 13 including the inner blade 11 .
On the other hand, with reference to FIG. 3 (b) in FIG. 3 (a), and mounting screw 3 is a side view of the drill body is a side view from a different angle of the drill body being mounted chip 1, the drill The main body 2 is provided with a shaft-shaped drill body 4 and a shank on the same axis. When the drill body 2 is attached to a tool holder (not shown), a part of the peripheral surface of the shank 5 is rotated. A flat surface 5a that functions as a stopper is formed.
[0023]
Referring to FIGS. 1 (a) and 1 (b) and FIG. 2 (a), a pair of sandwiching pieces 21 and 22 for sandwiching the tip 1 is formed at the front end of the drill body 4, and these A pocket for inserting the chip 1 is defined between the clamping surfaces 26 and 27 of the pair of clamping pieces 21 and 22. With the tip 1 inserted into the pocket 23, the mounting screw 3 is inserted into the through hole 21 a and the through hole 1 a of the holding piece 21 and screwed into the screw hole 22 a of the holding piece 22. It is pinched and fixed.
[0024]
One clamping piece 21 corresponds to the first block 13 forming the inner blade 11, and its clamping surface 26 abuts on a first clamped seat surface 1 b as the first block 13. The other clamping piece 22 corresponds to the second block 14 forming the outer blade 12, and its clamping surface 27 abuts on a second clamping seat surface 1 c as a clamping surface of the second block 14.
[0025]
The sandwiched seat surfaces 1b and 1c of the blocks 13 and 14 are arranged back to back with the rake surfaces 13a and 14a, respectively. Chip pockets 21b and 22b for chip disposal are formed above the rake surfaces 13a and 14a and on the side of the sandwiching pieces 21 and 22, respectively.
[0026]
In addition, spiral flute grooves 24 and 25 are formed on the peripheral surface of the drill body to discharge chips during drilling to the outside of the processing hole.
[0027]
Furthermore, a large-diameter first liquid passage pipe 6 having a hole through which a coolant flows is formed so as to penetrate the center from the end of the shank 5 to the base end of the drill body. The clamping surface 26 of the clamping piece 21 that communicates with the fluid passage pipe 6 and reaches the bottom of the pocket 23 from the base end of the drill body communicates with the second fluid passage pipe 7. A liquid passage groove 8 having a circular arc shape in section extending from the end to the tip is formed.
[0028]
As a major feature of the present invention, the liquid passage groove 8 is partially overlapped with the notch portion 1g of the chip 1. The notch portion 1g is used as a liquid passage, and the coolant is used for discharging chips. It can discharge | emit into the inner blade side flute groove 24 [refer FIG.1 (b)]. Then, by discharging the coolant into the inner blade side flute 24 groove, it is possible to reliably discharge chips from the inner blade that are formed in an umbrella shape and are not so good in discharging performance. .
[0029]
Further, the present invention is characterized by the cross-sectional shape of the flute groove in order to improve the chip disposal on the inner blade side. Hereinafter, this feature will be described.
[0030]
Referring to FIG. 9 which is a VV sectional view of FIG. 1, the sectional shape of the inner blade side flute groove 24 of the drill body 2 is formed in a two-arc shape. As a result, chips from the inner blade, which are formed in an umbrella shape and are not so good in discharge, are gently fitted into either one of the arcs, and the drill body is swayed in the radial direction and discharged. Therefore, it becomes possible to make it difficult to generate clogging of chips.
[0031]
Hereinafter, other features of the present invention will be described.
[0032]
Referring to FIG. 4 which is a sectional view taken along the line II of FIG. 1 and FIG. 5 which is a sectional view taken along the line II-II, the tip 1 has a front clearance angle α1 of the inner blade 11 greater than a front clearance angle α2 of the outer blade 12. Is also big.
[0033]
This point will be described below. The inner cutter 11 of the tip 1 needs to increase the front clearance angle α1. This is because the drilling direction angle of the trajectory being processed (spiral motion trajectory) at a specific point on the cutting edge increases toward the inside. On the other hand, the outer cutter 12 may have a smaller front clearance angle than the inner cutter because the drilling direction angle of the trajectory being processed (spiral motion trajectory) at a specific point on the cutting blade is larger toward the outer side. For example, referring to FIG. 6, the angle α1 with respect to the drilling direction in the spiral movement locus L1 at the point P1 of the inner blade during drilling is greater than the angle α2 with respect to the drilling direction in the spiral motion locus L2 of the point P2 of the outer blade. Therefore, in order to avoid interference with the bottom surface of the hole on the inner blade 11 side, a large clearance angle is required. On the other hand, a relatively small clearance angle may be used on the outer blade 12 side.
[0034]
Therefore, in the present invention, focusing on this point, the blade edge angle can be increased by making the front clearance angle of the outer blade 12 smaller than the front clearance angle α1 of the inner blade 11. Thereby, the intensity | strength of the outer blade 12 which has a corner part can be improved.
[0035]
The size of the front clearance angle α1 of the inner blade and the front clearance angle α2 of the outer blade is not particularly limited as long as the relationship α1> α2, but the front clearance angle α1 of the inner blade is 9˜. It is preferable that the front clearance angle α2 of the outer blade is within a range of 12 ° and 6 ° to 10 °.
[0036]
When the front clearance angle β1 of the inner blade is less than 9 °, interference with the hole bottom tends to occur, and when it exceeds 12 °, the strength of the cutting blade tends to decrease. Further, when the front clearance angle α2 of the outer blade is less than 6 °, there is a tendency that interference with the hole bottom tends to occur. On the other hand, when it exceeds 10 °, the strength of the cutting blade tends to decrease.
[0037]
Next, referring to FIG. 7 which is a cross-sectional view taken along the line III-III of FIG. 1 and FIG. 8 which is a cross-sectional view taken along the line IV-IV, the end faces of the sandwiching pieces 21 and 22 The angle γ1 is smaller than the clearance angle γ2 of other portions. With such a configuration, the chip 1 is prevented from entering between the end face of the drill body 2 and the bottom of the hole even when chips are instantaneously directed toward the bottom of the hole. Therefore, the chip dischargeability is good.
[0038]
The clearance angle γ1 of the portion adjacent to the chip pockets 21b and 22b and the clearance angle γ2 of other portions are not particularly limited as long as the relationship of γ1 <γ2, but the chip pocket 21b, The clearance angle γ1 of the portion adjacent to 22b is preferably in the range of 0 ° to 5. When the clearance angle γ1 of the portion adjacent to the chip pockets 21b and 22b is less than 0 °, there is a tendency that interference with the hole bottom tends to occur. On the other hand, when the clearance angle γ1 exceeds 5 °, the end surface of the drill body 2 and the hole bottom There is a tendency for chips to enter easily.
[0039]
In addition, it is not necessary to have both of the sandwiching pieces 21 and 22 to have such a configuration of the end face, and only one of them may be provided.
[0040]
Next, referring to FIG. 3, the drill body 2 has an overhang amount α that protrudes the upper ridge line 27 of the outer blade side chip pocket 21 b to the outer side of the upper ridge line 25 a of the upper ridge line 25 a of the outer blade side flute groove 25. (W> 0). Thereby, it can suppress that the diameter of a chip becomes large by forming a roof (overhang | projection part) in the upper part of the outer blade side chip pocket 21b. Thereby, it is possible to make chip discharge | emission property favorable.
[0041]
The overhang amount w is not particularly limited, but is preferably in the range of 0.5 to 1.2 mm. If w is less than 0.5 mm, the effect of reducing the chip diameter is weak, while if it is greater than 1.2 mm, the chip discharge tends to deteriorate.
[0042]
Note that the configurations of the throw-away tip and the throw-away tip drill body of the present invention are not limited to the examples of the drawings described above, and the design is changed as appropriate without departing from the scope of the present invention. be able to.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a throw-away tip and a drill body according to an embodiment of the present invention, where (a) is a view seen from the back side of the tip, and (b) is a view seen from the front side of the tip. It is.
2A is a perspective view seen from the front side of the chip, and FIG. 2B is a perspective view seen from the back side.
FIG. 3A is a front view of the drill body, and FIG. 3B is a side view of the drill drill body.
4 is a cross-sectional view taken along the line II of FIG.
5 is a cross-sectional view taken along the line II-II in FIG.
6 is an explanatory diagram for illustrating a mode of spiral movement during processing at a specific point of the cutting edge with respect to the chip of FIG. 1; FIG.
7 is a cross-sectional view taken along the line III-III of FIG.
8 is a sectional view taken along line VI-VI in FIG.
9 is a cross-sectional view taken along the line VV in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tip 2 Drill main body 1a Through-hole 11 Inner blade 12 Outer blade 13 First block 14 Second block 24 Inner blade side flute groove 25 Outer blade side flute groove 1g Notch parts 21 and 22 Clamping pieces 6 and 7 Through hole 8 Flow groove

Claims (2)

A first block whose inner edge is formed at the front end, the throw-away tip and a second block outer cutter formed at the front end,
A throw-away drill and a drill body that Ru provided with a pair of holding pieces for clamping the cutting insert,
The first block has a notch formed at the rear end corner,
On the peripheral surface of the drill body, an inner blade side flute groove for discharging chips from the inner blade and an outer blade side flute groove for discharging chips from the outer blade are formed,
The drill body includes a liquid passing pipe that penetrates in the axial direction and reaches one of the holding pieces, and a liquid passing groove that communicates with the liquid passing pipe and is provided on a holding surface of the holding piece. A throw-away drill characterized in that a part of the cutout portion and the cutout portion overlap each other . Indexable drill according to claim 1, wherein the cross-sectional shape before Symbol inner blade side flutes grooves is two arcuate.

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