JP2002326110A - Throw away tip for drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new throw away tip 1 for a drill with a one-tip type with two similar tips, that can be used for perforation of material of different diameter by offsetting a mounting position, while preventing reduction of a discharging function of chips in perforation, to further improve a perforating characteristic comparing with the prior art. SOLUTION: A tilting angle θ1 of a cutting edge 12b of an outer blade 12 for cutting the peripheral ridge of a hole, extending from the top 12a facing to the perforating direction in the inner direction of the tip 1 is set larger than a tilting angle θ2 of a cutting edge 11c of an inner blade 11 for cutting the central part of the hole, extending from the top 11a facing to the perforating direction in the outer direction of the tip 1, and increment of the width of the chip generated from the outer blade 12 in offsetting is controlled, thereby preventing reduction of the discharging function. A blade width Ew1 of the inner blade 11 is set larger than a blade width Ew2 of the inner blade 12, thereby increasing an offset amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drill insert for drilling used for drilling.

[0002]

2. Description of the Related Art As a drill used for drilling, in addition to a normal solid type drill integrally formed as a whole, a throw-away tip separate from a drill body (holder). There is a so-called throw-away type drill in which a cutting blade is formed on the top, and the cutting blade can be detachably attached to a tip of a holder by a screw or the like.

[0003] The above-mentioned indexable drill has two
There are a chip-type drill and a one-chip-type drill. Among them, the former two-chip type throw-away drill cuts a central portion of a hole as described in, for example, JP-A-10-29108. It is configured by mounting two chips, a tip having an inner blade and a tip having an outer blade for shaving the peripheral portion of the hole, at the tip of the holder.

In the invention described in the above publication, both an inner blade and an outer blade are formed on a single chip, and the same chip is also used as an inner blade chip or an outer blade chip depending on the mounting direction and position of the holder. It is also configured to be able to.

[0005] However, this two-chip type configuration is suitable for a large drill having a large processing diameter, but if it is to be applied to a small drill having a processing diameter of, for example, below about φ10, it is difficult to attach the tip to the tip of the holder. There are problems such as insufficient space for chip mounting or space for chip discharge, and very small screws for chip mounting, resulting in insufficient mounting strength. there were.

As the one-chip type throw-away drill, for example, as described in Japanese Patent Application Laid-Open No. H10-328918, a drilling face similar to the tip shape of a conventional solid type drill faces in the drilling direction. A pair extending from the top located on the rotation axis to both sides,
It is common to use a tip having a long blade ridge over the entire length of the radius of the processing hole.

However, in the above-mentioned chip shape, since a large cutting resistance is applied to the chip at the time of drilling, one chip is
As shown in the figure of the above-mentioned publication, it is necessary to firmly fix to the tip of the holder with two screws, and it is necessary to increase the thickness of the chip, so that a space for chip discharge is secured. There was a problem that it was not easy.

Accordingly, the inventor has previously provided an inner cutter for cutting the center of the hole and an outer cutter for cutting the peripheral portion of the hole. A one-chip type throw-away chip similar to two chips and formed on one chip in the same arrangement as that of the outer blade of the chip was developed (Japanese Patent Laid-Open No. 11-188518).

In the one-chip type throw-away insert similar to the above-described two-chip insert, the inner blade only needs to have a length sufficient to cut the center of the hole, and the outer blade also needs to cut the peripheral edge of the hole. As long as it has a length, the cutting resistance applied to the chip at the time of drilling can be reduced as compared with the conventional one-chip type.

Therefore, the thickness of the inner blade and the outer blade can be reduced, and the number of screws to be attached to the holder is one.
It can be used as a book, and a sufficient space for chip discharge can be secured.

Accordingly, the present inventors have further studied a one-chip type throw-away chip similar to the above-mentioned two chips, and have found that the structure described in the above publication has room for further improvement in terms of drilling characteristics. .

SUMMARY OF THE INVENTION An object of the present invention is to provide a new indexable insert for a drill, which is a one-chip type similar to a two-chip type and has improved drilling characteristics as compared with the conventional one.

[0013]

Means for Solving the Problems and Effects of the Invention
As shown in FIGS. 6 (a) and 6 (b), for example, as shown in FIGS. 6 (a) and 6 (b), the one-chip type throw-away chip has a top 11a facing the drilling direction, and a top 11a extending inward and outward of the tip 1 from the top 11a. A top portion 12a which is formed in a shape having blade ridges 11b and 11c extending downward in both directions, and the outer blade 12 also facing the drilling direction;
Blade ridges 12b and 12c extending downward from the top portion 12a in both the inward and outward directions of the tip 1 are formed, and a blade ridge 11c extending outward of the inner blade 11 and an outer blade 12c are formed.
When the inner blade 11 and the outer blade 12 are arranged such that the rotation trajectory when rotating the blade ridge 12b extending inwardly around the rotation axis Pv indicated by a dashed line in the figure intersects, A chip having a size corresponding to one processing diameter is mounted on a holder having a larger size with its mounting position offset radially outward, that is, as indicated by a black arrow in FIG. It is clear from subsequent studies by the inventor that the present invention has an advantage that it can be used for drilling (offset processing) with a diameter larger than a predetermined processing diameter by shifting the position and mounting it at the position shown in FIG. It became.

However, when the above-mentioned chip was further examined, the following facts became clear.

That is, in a drill incorporating a one-chip type throw-away tip similar to a two-tip type, conventionally, in order to discharge chips as smoothly as possible, a mounting seating surface is provided to facilitate the discharge of chips to the chip discharge side of the inner blade. Space (chip pocket)
In order to make it easy for chips to be discharged to the chip discharge side of the outer blade, the space is set as large as possible than a space (a chip pocket) provided in a stepped shape with respect to the mounting seat surface.

This is because the shape of the generated chips differs between the inner cutter and the outer cutter, and the mechanism of chip discharge differs.

That is, chips generated when a relatively large area in the center of the hole including the center of the hole corresponding to the rotation axis of the drill is cut by the inner cutter, the cutting speed by the inner cutter is reduced by the center of the hole. At 0, it increases outwardly from it, giving a three-dimensional helical shape in which cones with the vertex at the part corresponding to the center of the hole are piled up and down. In order to discharge the chips, it is necessary to maintain a continuous state without cutting as much as possible, and to continuously feed the chips into the flute grooves of the holder as the chips grow by the perforation processing.

On the other hand, chips generated when a relatively narrow region of the peripheral edge of the hole is cut by the outer cutter have a difference in the cutting speed between the rotating shaft side and the outermost peripheral side of the rotation locus of the outer cutter. Since it is not as large as the case of the inner blade, it has a band shape of a fixed width or a finely cut shape, and is easier to discharge than chips on the inner blade side.

Therefore, in the drill incorporating the above-mentioned tip, in order to discharge the three-dimensionally shaped chips from the inner cutter as smoothly as possible, the discharge space must be reduced by the fine chips from the outer cutter. It was thought that it was desirable to make the space as large as possible than the space for discharging air.

However, in the indexable insert 1 in which the inner cutter 11 and the outer cutter 12 are arranged as shown in FIGS. 6 (a) and 6 (b), particularly when the outer cutter 12 is used for the above-described offset machining, There was a case where the dischargeability of chips from the steel was reduced.

Then, the inventor examined how the chips change when the insert 1 of FIG. 6 is used for offset machining, and as a result, the insert 1 is moved radially outward to increase the machining diameter. It has been found that, when the offset is performed, the increment of the width of the chip band generated from the outer cutter 12 becomes remarkably large, and the dischargeability thereof is reduced.

In other words, in the normal machining shown in FIG. 6A, the area of the width wi ₀ of the radius r ₀ of the machining diameter is the area of the cutting by the inner cutter 11, and the three-dimensional chip The length of the generatrix of the cone substantially corresponds to the width wi ₀ . The area of the width wo _{0 is} an area of the cutting process by the outer cutter 12, and the width of the strip-shaped chip corresponds to the width wo ₀ .

On the other hand, the tip 1 is offset radially outward, that is, the rotation axis Pv is moved in the direction indicated by the black arrow in FIG. 6A, and is mounted at the position shown in FIG. 6B. , the radius of the machining diameter when the offset machining is increased to r _l, of the radius r _1, increased area of the cutting by the inner blade 11 in the width wi _1, and the area of the cutting by the outer cutter 12 wo Increase to ₁ .

However, in the chip 1 having the structure shown in FIG. 6, the increase in the radius of the processing diameter, that is, most of Δr = r ₁ −r ₀ is, as can be seen in these figures, the cutting by the outer cutter 12. This corresponds to an increase in the width of the area Δwo = wo ₁ −wo ₀ , and as a result, the width of the chip band from the outer cutter 12 is significantly increased. As a result, clogging occurs in the discharge space on the outer cutter 12 side, which originally has no room. It is easier to remove chips.

Therefore, as a result of further study, conventionally,
As shown in FIGS. 6 (a) and 6 (b), each of the blade ridges 11b of the inner blade 11 and the outer blade 12, all formed at substantially the same inclination angle,
11 c, 12 b, 12 c, a blade ridge 12 b extending inward of the outer blade 12, whose rotation trajectories cross each other, and an inner blade 1.
If the inclination angle of the blade ridge 11c extending outward in the first direction is made larger in the former than in the latter, and the amount of deviation of the intersection of the rotation trajectory at the time of offset is adjusted, the inner blade 11 is more inclined than before. Width increment △ wi of the cutting area
= Wi ₁ -wi ₀ is increased, and it has been found that the above-mentioned width increment Δwo of the region cut by the outer cutter 12 can be suppressed accordingly.

At this time, as shown in FIG. 6B, when the rotation locus of the inner blade 11 indicated by a two-dot chain line is superimposed on the outer blade 12, the position of the inward end 11d is: As the amount of the offset is increased, the point moves from point A to point B in FIG. 6B. At this stage,
Since the inner blade 11 and the outer blade 12 do not intersect and the holder holding the chip 1 hits the workpiece, cutting becomes impossible. In order to increase the amount of offset up to this use limit, it is conceivable to increase the blade width of the outer cutter 12, but in such a case, the width of the chips of the outer cutter 12 increases, and as described above, There is a risk that there will be a problem with evacuation.
Therefore, by making the blade width of the inner blade 11 larger than the blade width of the outer blade 12, it is possible to maintain good discharge of chips from the outer blade 12 and increase the offset amount up to the above-mentioned use limit. We have found what we can do and have completed the present invention.

That is, the invention according to claim 1 is a throwaway insert for a drill used for drilling,
An inner blade that cuts the center of the hole, and an outer blade that cuts the peripheral portion of the hole, and the inner blade and the outer blade each face the top in the drilling direction,
A blade ridge extending downwardly in both the inward and outward directions of the chip from the top portion, wherein the inclination angle of the inwardly extending blade ridge of the outer blade is the inclination of the outwardly extending blade ridge of the inner blade. An indexable insert for drilling, characterized in that the angle is larger than the angle and the blade width of the inner blade is larger than the blade width of the outer blade.

[0028]

Embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 (a) is a front view of a drill throw-away tip 1 according to an embodiment of the present invention, and FIG. 1 (b) is a bottom view showing the front end face of the tip 1 in the drilling direction. It is. FIG. 3A is a rear view of the chip 1, and FIG. 3B is a left side view of the chip 1 as seen from the front. 4A is a perspective view as viewed from the front side, and FIG. 4B is a perspective view as viewed from the back side.

As shown in these figures, the indexable insert 1 for a drill of this example has two back-to-back surfaces as a first seat surface 1b and a second seat surface 1c for attachment to a holder, and the first seat. A through hole 1a is formed so as to penetrate from the surface 1b to the second seating surface 1c, and into which a screw for attaching to the holder is inserted.

The chip 1 on the first seating surface 1b
1 for drilling around the rotation axis Pv.
(B) A rake face in which, when rotated in the direction indicated by the solid arrow, the portion on the front side of the rotation is recessed by one step from the first seating surface 1b in the rotation direction. 13
As a result, a projection 13 having a smaller thickness than the portion where the through hole 1a is formed is formed. The front flank 13b, which is a side surface on the front side in the drilling direction, of the projection 13 and the rake face 13a are formed. , The above-described inner blade 11 is formed.

Similarly, in a portion of the second seating surface 1c which is on the front side of rotation, the portion is a rake face 14a which is set back by one step from the second seating surface 1c in the rotation direction. The projection 1 is thinner than the portion where the through hole 1a is formed.
4 is formed, and a front flank 14b, which is a side surface on the front side in the drilling direction, of the protrusion 14 and the rake surface 14a.
The above-mentioned outer blade 12 is formed by the intersection ridge.

Further, a space formed in front of the rake face 13a and having a step difference from the first seating surface 1b is used to form a space for discharging chips from the inner cutter 11 with respect to the holder. A chip pocket, which is also formed in front of the rake face 14a and has a step difference from the second seating surface 1c, is provided between the holder and the space for discharging chips from the outer cutter 12. Chip pockets.

As described above, the inner blade 11 has a top 11a facing in the drilling direction, and a blade ridge 11 extending downward from the top 11a in both the inward and outward directions of the chip 1.
b, 11c.

On the other hand, the outer blade 12 also has a top portion 12a facing in the drilling direction as described above, and a tip 1 from the top portion 12a.
Are formed in a shape having blade ridges 12b and 12c extending downward and inclining both inward and outward directions.

The inner cutter 11 and the outer cutter 12 are used to cut the center of the hole by the inner cutter 11 and the peripheral edge of the hole by the outer cutter 12 almost simultaneously to perform smooth drilling. The tops 11a and 12a are arranged at substantially the same height in the drilling direction.

Further, the inner cutter 11 and the outer cutter 12 are arranged as shown in FIG.
(A) As shown by a two-dot chain line in (b), when the tip 1 is rotated about the rotation axis Pv, the tip 1 c extends outward of the inner cutter 11, and the tip 1 c extends inward of the outer cutter 12. The rotation trajectories of the extending blade ridges 12b are arranged so as to intersect with each other, and the inclination angle of the blade ridges 12b (θ ₁ in FIG. 1A) is set as described above in order to enhance the chip dischargeability as described above. Edge 11
c tilt angle of greater than [FIG 1 (a) θ ₂ in] (theta ₁
> Θ ₂ ).

That is, in the normal processing shown in FIG. 2A, the area of the width Wi ₀ of the radius R ₀ of the processing diameter is the area of the cutting by the inner cutter 11, and the area of the width Wo ₀ . Is an area of the cutting process by the outer cutter 12, and the outer cutter 1
The width of the strip of the chip leaving the 2 corresponds to the width Wo _0.

On the other hand, the tip 1 is offset radially outward, that is, the rotation axis Pv is moved in the direction indicated by the black arrow in FIG. 2A, and is mounted at the position shown in FIG. 2B. , the radius of the machining diameter when the offset machining is increased to R _l, of the radius R _l, increased area of the cutting by the inner blade 11 in the width Wi _1, and the area of the cutting by the outer cutter 12 Wo Increase to ₁ . In this case, the inclination angle theta ₁ of the blade edge 12b as described above, the inclination angle of the blade edge 11c theta ₂
Therefore, the amount of deviation at the time of offset between the intersections of the rotational trajectories of the two blade edges 12b and 11c is adjusted.

More specifically, as compared with the case where the inclination angles θ ₁ and θ _{2 of the two} blade ridges 12b and 11c are equal, the above-mentioned intersection position is located radially outward and the amount of deviation of the intersection position is smaller. Increment of the radius of the machining diameter, that is, the increment of the width of the region of the cutting operation by the inner cutter 11 occupying △ R = R ₁ -R ₀ △ Wi
= Wi ₁ -Wi ₀ increases, and the relative increase in the width of the area of the cutting process by the outer cutter 12, that is, the increase in the width of the chip band from the outer cutter 12 △ Wo = Wo ₁ -Wo has hitherto been achieved. Can be suppressed.

Therefore, clogging in the discharge space on the side of the outer cutter 12, which originally has no allowance, is suppressed, and a decrease in chip discharge performance is prevented.

The specific range of the two inclination angles θ ₁ and θ ₂ is not particularly limited, but the inclination angle θ of the blade edge 12b is
₁ is about 15 to 25 °, and the inclination angle θ ₂ of the blade ridge 11c is 5 to
Preferably, it is about 15 °.

When the inclination angle θ ₁ is less than the above range, the difference between the inclination angle θ ₂ and the inclination angle θ ₂ becomes small. At times, the effect of the present invention of suppressing the remarkable increase in the width of the chip band discharged from the outer cutter 12 is not sufficiently obtained, so that there is a possibility that the discharge property of the chip from the outer cutter 12 may be reduced. is there.

On the other hand, when the inclination angle θ ₁ exceeds the above range, the load applied to the top 12a of the outer cutter 12 increases, which may cause chipping or the like, and may be cut by the outer cutter 12. Since the material to be cut does not curl well, the outflow of chips becomes worse, and the cutting performance of the outer cutter 12 may be reduced.

Taking these facts into consideration, it is more preferable that the inclination angle θ _{1 be} around 20 ° even in the above range.

When the inclination angle θ ₂ is less than the above range,
The load applied to the top 11a of the inner blade 11 may be reduced, and the cutting performance of the inner blade 11 may be reduced.

On the other hand, when the inclination angle θ ₂ exceeds the above range, the difference from the inclination angle θ 1 becomes small and the effect of the present invention cannot be sufficiently obtained. There is a possibility that the discharge property of the water may decrease. Also, the inner blade 11
In addition to the possibility that the load applied to the top 11a of the inner blade 11 becomes large, causing a breakage, etc., a space for curling the chips neatly in the drilling direction of the inner cutter 11 and discharging the chips as a three-dimensional shape as described above, Since it cannot be secured with a sufficient size, there is a possibility that the chip discharge performance of the inner blade 11 may be reduced.

Taking these facts into consideration, it is more preferable that the inclination angle θ _{2 be} in the range of 6 to 12 ° in particular.

The inner blade 11 and the outer blade 12 are set so that [the blade width Ew ₁ of the inner blade 11> the blade width Ew ₂ of the outer blade 12]. The reason for setting these blade widths in this manner is as follows.

As shown in FIG. 2B, when the rotational locus of the inner blade 11 indicated by a two-dot chain line is superimposed on the outer blade 12, the position of the inward end 11d is determined by the amount of offset. Is gradually increased from point A to point B in FIG. At this stage, the inner blade 11
Since the holder holding the chip 1 does not intersect with the outer blade 12 and hits the workpiece, cutting becomes impossible. In order to increase the amount of offset to this use limit, the outer cutter 12
It is also contemplated to increase the blade width Ew ₂ of, but when doing so, there is a possibility that out problems in chip discharge performance as the width of the chips of the outer cutter 12 is increased above. Therefore, the blade width Ew ₁ undercutter 11 to be larger than the blade width Ew ₂ of the outer cutter, with a to maintain good ejection of the chips of the outer cutter 12, increasing the amount of offset to the usage limit can do.

The above two blade widths Ew₁, Ew_TwoEspecially limited
Although not specified, the blade width Ew of the inner blade 11 ₁Is the blade width of the outer blade 12
Ew_TwoIt is preferably larger by 10% to 30%. Inside
Blade width Ew of blade 11₁Is the blade width Ew of the outer blade 12._Two10% than
If the blade widths are equal,
The present invention that makes the amount of offset larger than
Is not sufficiently obtained, while the blade width E of the inner blade 11 is hardly obtained.
w₁Is the blade width Ew of the outer blade 12._TwoMore than 30% larger than
In case, the blade width Ew of the outer blade_TwoIs too short to use limit
There is a problem that the width of the set does not increase.

In this example, the inner blade 11 extends outward.
The blade edge 11c descends in the drilling direction as described above.
Not only is it inclined, but also the rake face 13a
In both cases, as shown in FIG.
On the other hand, it is inclined backward (tilt angle θ _Three) To make the edge 11
b.

With this arrangement, a larger space for chip discharge is provided in front of the rake face 13a to allow the chips to curl more smoothly in this space, and to be smoother along the receding slope of the rake face 13a. Another advantage is that it can be discharged into the flute groove of the holder.

With the above arrangement, the component force in the direction of pressing the chip 1 in the direction of the outer blade 12 out of the cutting resistance generated at the time of drilling becomes large. There is also an advantage that the working diameter of the drilling can be maintained at a predetermined value against the component force in the direction of pressing the inward in the radial direction.

The chip 1 of this example provided with the above-mentioned components has a pocket 2 between a pair of holding pieces 21 and 22 at the tip of the holder 2 as shown by, for example, solid arrows in FIGS. 5 (a) and 5 (b).
3 while being inserted and positioned,
The screw 3 is inserted through the through hole 21a of the chip 1 and the through hole 1a of the chip 1 and screwed into the screw hole 22a of the holding piece 22, thereby being fixed to the tip of the holder 2 and used for drilling. .

In this fixed state, the rake face 13
The space for chip discharge formed between the holding pieces 22 and 21 on the front surface of each of the holders 2 and 21 is a holder 2.
Are communicated with the spiral flute grooves 24 and 25 formed on the peripheral surface of the inner blade, whereby chips from the inner cutter 11 and the outer cutter 12 are smoothly discharged through the flute grooves 24 and 25 to the outside of the holes. You.

The configuration of the indexable insert for a drill according to the present invention is not limited to the above-described example of the drawing, and the design can be changed as appropriate without changing the gist of the present invention.

[Brief description of the drawings]

FIG. 1A is a front view of a drill throw-away tip according to an embodiment of the present invention, and FIG.
It is a bottom view which shows the front end surface which faces the perforation direction of the said chip | tip.

FIGS. 2 (a) and 2 (b) show changes in the rotation trajectories of the inner cutter and the outer cutter and the change of the inner cutter and the outer cutter of the example of FIG. It is the schematic explaining the change of the cutting range.

3 (a) is a rear view of the chip of the example of FIG. 1, and FIG. 3 (b) is a left side view of the chip as viewed from the front of FIG. 1 (a).

FIG. 4A is a perspective view of the chip of the example of FIG. 1 as viewed from the front side, and FIG. 4B is a perspective view as viewed from the back side.

5 (a) is an exploded perspective view of the structure of attaching the chip of the example of FIG. 1 to the tip of the holder, as viewed from the front side of the chip, and FIG. 5 (b) is an exploded view as viewed from the rear side. It is a perspective view.

FIGS. 6 (a) and (b) show changes in the rotation trajectories of the inner cutter and the outer cutter, and the cutting range of the inner cutter and the outer cutter during the normal machining and the offset machining of the conventional insert. It is a schematic diagram explaining a change.

[Explanation of symbols]

1 Slow drill away tip 11 inner cutter 12 outer cutter 11a, 12a apex 11b, 11c, 12b, 12c blade edges theta _1, theta ₂ inclination angle Ew _1, Ew ₂ blade width

Claims (1)

[Claims] An indexable insert for drilling used in drilling, comprising: an inner blade for cutting a central portion of a hole; and an outer blade for cutting a peripheral portion of the hole. And a blade ridge extending downward and inclining in both the inward and outward directions of the chip from the apex, and the angle of inclination of the inwardly extending blade ridge of the outer blade is directed outward of the inner blade. A throw-away insert for a drill, characterized in that the angle of inclination of the extending blade ridge is larger than the blade width of the inner blade, and the blade width of the inner blade is larger than the blade width of the outer blade.