JPH10109210A - Throw away tip for spade drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To break a chip into a proper length for improving chip processing ability by properly twisting the chip cut with a cutting edge part nearer to an outer periphery side than a chip breaker on the most outer periphery side where the chip is apt to be discharged in a slender strip in the case of drilling a metal relatively lower in hardness. SOLUTION: A part near the outer periphery of each cutting face is provided with a recessed part 14 in succession to a chip breaker 6 along cutting edges 2, 3 to form a chip abutting face 16a against which a chip cut by cutting edges 2, 3 nearer to an outer periphery side than chip breakers 9, 10 on the most outer periphery side can collide. The outside edge of the chip abutting face 16a is formed obliquely in range to a tip cutting edge 2 at a sight from the side of the cutting face 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throwaway insert for a spade drill (hereinafter also referred to as a throwaway insert or simply an insert) suitable for drilling (drilling) a large diameter or deep hole.

[0002]

2. Description of the Related Art FIG. 17 shows an example of this type of a throw-away chip 1. As shown in FIG. This is made of cemented carbide or the like, has a substantially pentagonal plate shape with a predetermined thickness, and has chip breakers 6, 7 having a predetermined width substantially parallel to both left and right tip cutting edges 2, 3. In this way, the chips generated at the time of drilling are sufficiently curled and cut and discharged, which is suitable for deep hole processing. In order to reduce the cutting resistance, the tip shown in the figure has an appropriate number (generally, 1 to 4 places) of nicks (notches) 8, 9, 10 are provided asymmetrically. When the insert 1 is used to pierce a workpiece having good machinability such as cast iron or a workpiece having relatively high hardness, chips are cut into appropriate lengths and the feed speed is reduced by the nick 8. , 9, and 10, the chips to be discharged are divided into predetermined widths at each nick, and are discharged as relatively short and thin chips.

[0003]

However, in such a chip, the workpiece to be machined is HB250 or less such as alloy steel such as SKD, SCM, SNCM, etc.
When drilling a relatively low-hardness metal material such as HB300 or less such as S50C or the like, there is a problem in the chip disposability due to the material of the workpiece. That is, when the above-mentioned tip 1 is used in such a processing, the peripheral speed is small at the portion of the tip cutting edges 2 and 3 near the central axis J, so that the chips to be cut and discharged are relatively curled, such as being appropriately curled. Although it is discharged in a good shape, the peripheral speed is high on the outer peripheral side of the cutting blades 2 and 3, and therefore, as shown in FIG.
Is easy to extend long.

[0004] That is, the chips tend to extend on the rake face 4 in the direction perpendicular to the tip cutting edge 2, but as described above, chips discharged from a portion near the outer peripheral edge of the cutting edge 2, particularly the outermost peripheral side. Chips K generated by cutting with the tip cutting edge 2 on the outer peripheral side of the nick 9 are divided into narrow pieces by the nick 9, but are elongated in a straight line without being divided by an appropriate length. Easy to be discharged. The chips K that are elongated and discharged linearly in this manner are supplied to the tool (tip holder).
This is dangerous because it is entangled with and swung around, which may cause a stop of the machine and reduce the work efficiency, and in some cases, may damage the chip. Moreover,
Such chips cause damage to the inner surface of the perforated hole, causing problems such as a reduction in dimensional accuracy. As described above, in the case of the above-mentioned conventional chip, there is a problem in the chip disposability when drilling a relatively low hardness workpiece.

The present invention has been devised in view of such a problem, and has as its object the purpose of forming a long and narrow hole when drilling a workpiece (metal) having a relatively low hardness. A spade drill throw that can cut chips at an appropriate length by appropriately twisting the chips cut at the cutting edge part on the outer peripheral side from the nick on the outermost peripheral side that is likely to be discharged, and improving the chip disposability Its purpose is to provide away chips.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a chip breaker which is recessed along the left and right tip cutting blades and has an appropriate number of nicks on the left and right tip cutting edges. In the throwaway insert for a spade drill, a concave portion is continuously provided from the chip breaker with respect to a portion near the outer periphery of each rake face, and chips cut by the tip cutting edge on the outer peripheral side from the outermost nick collide with the chip. A possible chip contact surface is formed, and the outer edge of the chip contact surface is
When viewed from the rake face side, it is continuous with an arc shape or an inclined shape with respect to the tip cutting edge. Here, the outer edge of the chip contact surface refers to an intersection (ridge line) between the rake surface and the concave portion (concave surface).

In the above-mentioned means, the chip contact surface is formed on a vertical line extending from a substantially center of the outermost nick provided on the leading edge cutting edge to a rake surface substantially perpendicular to the leading edge cutting edge. Although it may be provided on the outer peripheral cutting edge side including or on the outer peripheral cutting edge side from the vertical line, the chip contact surface is substantially from the center of the outermost peripheral nick of the distal cutting edge to the distal cutting edge. A vertical line extending vertically on the rake face and a vertical line extending from the outer peripheral edge of the leading edge cutting edge to the rake surface substantially perpendicular to the leading edge cutting edge are provided so as to substantially exist in a range between the vertical line extending on the rake face and the vertical edge extending substantially perpendicular to the leading edge cutting edge. Is preferred. In addition, the nick on the outermost peripheral side refers to a nick that exists at a portion near the outer peripheral edge of the tip cutting edge when there are a plurality of nicks for any of the left and right tip cutting edges, but when there is one nick, That is the meaning of the nick itself.

When drilling with the spade drill indexable insert, the chips cut by the tip cutting edge extend in a direction perpendicular to the tip cutting edge, and are scooped and discharged by a chip breaker (breaker groove) provided along the cutting edge. However, the chip on the outermost side divided by the nick on the outermost side of the nicks collides with the above-mentioned chip contact surface after extending in a direction perpendicular to the cutting edge and is pressed. The outer edge of the chip contact surface is not parallel to the tip cutting edge as viewed from the rake face side, but is continuous in an arc shape or an inclined shape with respect to the tip cutting edge. Of the chips generated, those that collide with the chip contact surface are guided to the non-parallel outer edge, and are discharged by a torsional action in the width direction. Thus, the discharged chips are twisted, and in the process, are discharged while being cut into appropriate lengths by work hardening. As a result, the discharged chips are less likely to become entangled with the holder, which makes the drilling more efficient and is also effective in preventing breakage of the chips.

In the above-mentioned means, the chip contact surface includes at least a vertical line extending from a substantially center of the nick on the outermost peripheral side of the tip cutting edge to a rake surface substantially perpendicular to the tip cutting edge, and an outside of the tip cutting edge. It is particularly preferable that it be present in a range sandwiched by a vertical line extending on the rake face substantially perpendicularly to the leading edge cutting edge from the peripheral edge. That is, in the present invention, when viewed from the rake face side, the outermost peripheral side with respect to the chip contact surface having an outer edge that is not parallel to the tip cutting edge but is continuous in an arc shape or inclined with respect to the tip cutting edge. The chip cut by the cutting edge on the outer peripheral side from the nick collides to give a twisting action, and the chip has a maximum width between the two vertical lines (distance), that is, the tip cutting edge. It is considered that the length of the cutting edge existing on the outer peripheral side from the nick on the outermost peripheral side is the maximum width and extends to the rake face side substantially perpendicularly to the tip cutting edge. Therefore, if the chip contact surface exists as described above, the chip can be twisted efficiently because the chip can be subjected to the twisting action almost completely in the width direction.

However, the chip contact surface of the present invention is:
As described above, it may be provided so as to substantially correspond to the range sandwiched between both vertical lines, and although there is a reduction in the twisting action, it exists in a smaller range as long as chips can be discharged while twisting. It may be provided as follows. Note that, in the present invention, the outer edge of the chip contact surface is provided with a twisting action in the width direction to the chips by being connected to the arc-shaped or inclined to the tip cutting blade as viewed from the rake face side, Therefore, the vertical distance from the tip cutting edge to the outer edge of the chip contact surface may be longer or shorter as approaching the outer peripheral cutting edge, but the outer edge of the chip contact surface is
It is preferable that the connection is made such that the vertical distance from the leading edge cutting edge becomes longer as approaching the outer peripheral edge. In this case, the torsional action in the width direction of the chips can be applied from the central axis side to the outer peripheral side, so that the chips can be discharged without being wound around the central axis side, thereby improving the chip disposability. It is.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying a throwaway tip for a spade drill according to the present invention will be described.
This will be described in detail with reference to FIGS. In the drawing, reference numeral 1 denotes a throwaway tip of the present example made of a cemented carbide or the like,
It has a substantially pentagonal plate shape having a predetermined thickness, and chip breakers 6 and 7 having a predetermined width are provided on the rake faces 4 and 5 of the left and right tip cutting edges 2 and 3 substantially parallel to the respective cutting edges 2 and 3. It is recessed in an arc shape in cross section (see FIG. 6). In this example, the left and right tip cutting edges 2,
The nicks 8, 9, and 10 are provided so as to divide the left and right cutting blades 2 and 3 into substantially equal parts at one place on one side (FIG. 2 left) and two places on the other side (FIG. 2 right). I have.

Then, the chip breakers 6 and 7 are continuous with the outer peripheral cutting edges (margins) 12 and 13 of the rake faces 4 and 5 from the chip breakers 6 and 7, and the rear ends (see FIG. 2) along the outer peripheral cutting edges 12 and 13. Upper (upper) sides are provided with concave portions (concave grooves) 14 and 15 having a narrow U-shaped or V-shaped arc-shaped cross section (see FIG. 7). The recesses 14 and 15 are formed so that the tip cutting edges 2 and 3 have substantially the same depth as the chip breakers 6 and 7 and become shallower toward the rear end (see FIG. 8). Each of the concave portions 14 and 15 is formed such that the concave portion side (wall surface side) of the boundary line (ridge line) with the rake faces 4 and 5 forms a chip contact surface.

The concave portion 14 provided on the rake face 4 of the cutting edge 2 provided with two nicks is provided at each rake face from substantially the center of the outermost nick 9 to the tip cutting edge 2 substantially perpendicularly. 4
A point P1 slightly closer to the central axis J than the vertical line S1 extending upward.
From the outer peripheral cutting edge 12 side,
Is formed so as to form a chip contact surface 16. However, a portion 16a of the chip contact surface 16 opposite to the outer peripheral cutting edge 12 and its outer edge 16s are point P
1 extends to the rear end side of the chip 1 at an inclination angle α of about 60 degrees with respect to the tip cutting edge 2, so that the outer edge 16 s of the chip contact surface 16 a becomes closer to the outer peripheral cutting edge 12 so that the tip cutting edge becomes closer. 2 are arranged so that the vertical distance d from them becomes longer (see FIGS. 2 and 4). Of the chip contact surface 16 formed by the concave portion 14, this portion 16a mainly forms a chip contact surface (shaded line portion in the figure) of the chip cut by the tip cutting edge 2 on the outer peripheral side from the nick 9 on the outermost peripheral side. It is formed as follows. The chip contact surface 16a and its outer edge 16
s is a vertical line S extending from the point P1 and extending from the outer peripheral edge 17 of the tip cutting edge 2 to the rake face 4 substantially perpendicular to the tip cutting edge 2.
It runs over two.

On the other hand, a concave portion 15 provided on the rake face 5 of the cutting blade 3 provided with one nick has a vertical shape extending from the substantially center of the nick 10 to the rake face 5 substantially perpendicular to the tip cutting blade 3. It is provided on the outer peripheral cutting edge 13 side from the point P2 on the outer peripheral cutting edge 13 side slightly from the line S3, and a portion along the inside of the concave portion 15 is formed so as to form a chip contact surface 18. However, a portion 18a of the chip contact surface 18 opposite to the outer peripheral cutting edge 13 and its outer edge 18s are inclined from the point P2 to the front cutting edge 3 at an inclination angle α of about 60 degrees with respect to the rear end side of the chip 1. This portion 18a is mainly formed so as to form a chip contact surface of the chip to be cut by the tip cutting edge 3 on the outer peripheral side from the nick 10 on the outermost peripheral side. The chip contact surface 18a and its outer edge 18s are continuous from the point P2, and are continuous from the outer peripheral edge 19 of the distal cutting edge 3 beyond the vertical line S4 extending on the rake face 5 substantially perpendicular to the distal cutting edge 3. I have.

The cutting edge angle β in this embodiment is 132 degrees. Further, through holes 20 and 2 for inserting set screws for fixing to the holder H as shown in FIG.
0 is drilled. The notch 21 at the center on the rear end side of each of the chips 1 as viewed from the front is a positioning portion when the chip 1 is attached to the holder H.

Next, such an embodiment of the present invention is mounted on a holder and a relatively low-hardness metal such as S45C or S45C is used.
A case in which a hole having a HB of about 300 or less such as 50C is drilled will be described (see FIG. 9). That is, the chips discharged while being narrowly divided by the nicks 8, 9 and 10 are basically discharged in a direction perpendicular to the leading edge cutting edges 2 and 3. At this time, the cutting edges 2, 3 inside the outermost nicks 9, 10
Chips are cut by the chip breakers 6 and 7 provided in parallel with the cutting blades 2 and 3 because the peripheral speed of the cutting blades at that portion is low. It is cut off at an appropriate length without much extension, and is discharged almost without problems. That is, as shown in FIG. 9, for example, on the rake face 4 side of the cutting edge 2 provided with two nicks, the chips K1 and K2 cut by the cutting edge 2 inside the nick 9 on the outermost peripheral side are: Since the peripheral speed of the cutting blade at that portion is also low, it is scooped by the chip breaker 6 provided in parallel with the cutting blade 2 and collides with the tip of the holder H. The nicks are also discharged at the cutting blade 3 provided with one nick.

On the other hand, chips to be cut by the cutting edges 2 and 3 outside the outermost nicks 9 and 10 extend substantially perpendicularly to the cutting edges 2 and 3 and from the chip breakers 6 and 7 to the respective recesses 14 and 3. 1
Step into 5. And nick is 2 as shown in FIG.
On the rake face 4 side of the provided cutting edge 2, the outer peripheral cutting edge 1
2 is pressed against the chip contact surface 16a on the opposite side. Since the chip contact surface 16a and its outer edge 16s are connected to the tip cutting edge 2 in an inclined manner, the strip-shaped chip K collides with the inclined portion 16a from the side near the point P1. Then, as shown in FIG. 10, the chip K is subjected to a twisting action so that the portion near the axis in the width direction is pressed against the chip contact surface 16a and its outer edge 16s, and becomes outward as indicated by the arrow in the figure. . In this manner, the chips K continuously discharged by the torsional action are twisted and discharged as shown in FIG. Chip K as shown in FIG.
Becomes

Further, on the rake face 5 side of the cutting blade 3 provided with one nick, as shown in FIG.
Although not only the inclined chip contact surface 18a formed by the concave portion 15 and the outer edge 18s thereof but also a part thereof is pressed against the chip breaker 7a parallel to the cutting edge 3, the chip K still has the width as shown in FIG. It is continuously discharged by receiving a twisting action in the direction of the arrow so that the portion near the axis in the direction becomes outward. In this manner, the pieces are successively cut at a certain length and discharged as described above.

As described above, the chips K cut by the cutting edges outside the outermost nicks 9 and 10 are continuously discharged while being subjected to a twisting action on one side during the discharging process. At a certain torsion angle, the chips are cut, and as a result, the chips are cut into pieces having an appropriate length. Thus, the chip controllability is improved, and entanglement with the holder H, breakage of the chip, and deterioration of the accuracy of the inner surface of the hole to be drilled are prevented.

In the previous example, on the rake face 5 side of the cutting edge 3 provided with one nick, the outer edge 18s of the chip contact surface 18a is raked from substantially the center of the nick 10 to a direction substantially perpendicular to the tip cutting edge 3. 5 is provided so as to continue from the point P2 closer to the outer periphery than the vertical line S3 extending on the outer periphery side. As described above, this is similar to the rake face side of the cutting blade provided with two nicks. It is preferable that the vertical line S3 be provided so as to continue from the portion closer to the central axis to the outer peripheral side than the vertical line S3. This is because the twist can be efficiently given to the chips.

In the previous example, the outermost nicks 9, 1
As the outer edges 16s, 18s of the chip contact surfaces 16a, 18a, on which the chips cut by the leading edge cutting edge on the outer peripheral side from 0 can collide, approach the respective outer peripheral cutting edges 12, 13 at an inclination angle α, the leading edge cutting edges 2, Although the straight line is inclined and connected linearly so that the vertical distance d from 3 becomes long, as shown in FIG. 15, the width of the outer peripheral cutting edge 12 portion of the chip breaker 6 is locally expanded in an arc shape. By providing the recess 24, a chip contact surface 26a against which chips cut by the tip cutting edge on the outer peripheral side from the nick 9 on the outermost peripheral side may collide may be used. In this case, the outer edge 26s of the chip contacting surface 26a is formed in an arc shape and connected so that the vertical distance from the tip cutting edge 2 becomes longer as approaching the outer peripheral cutting edge 12. In addition, FIG. As shown, the concave portion 34 is provided with the tip cutting edge 2 on the outer peripheral side of the nick 9 on the outermost peripheral side.
The inclination angle α of the outer edge 36 s of the chip contact surface 36 a against which the chips to be cut can collide with the tip cutting edge 2 is opposite to that of the previous example.
It may be linked as. In this way, the chips are twisted in the opposite direction. 15 and 16, the same reference numerals are given to portions common to FIG.

Further, in the previous example, the concave portion does not protrude from the rear end of the chip. However, the concave portion may penetrate. Also, the number of nicks is appropriately set according to the drill blade diameter (outer diameter of the cutting blade), but the present invention can be embodied regardless of the number. The direction in which the outer edge of the chip contact surface against which the chips cut by the tip cutting edge on the outer peripheral side from the nick on the outermost peripheral side can collide with each other is inclined at an angle or tangent angle of 30 to 75 with respect to the tip cutting blade. It is appropriate to set it in the range of degrees.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment shown in FIGS. 1 to 8, the drill has a cutting edge diameter of 20 mm and the tip cutting edge is lowered by 0.4 mm.
In the case where the width of the chip breaker along this is 3.5 mm and the arc radius of the cross section is 3 mm, the chip contact surface against which the chips cut by the tip cutting edge on the outer peripheral side from the outermost nick can collide. The width of the concave portion formed on each cutting edge side is 3.
5 mm (constant radius of the cross section is about 2 mm constant), the length toward the rear end is about 7 mm, and the concave portion is formed so as to be narrow, and the SCM415 (HB
A block of about 200) was perforated under the following cutting conditions, and the state of the discharged chips was observed. In addition,
The vertical distance between the vertical line S1 on the rake face 4 side of the cutting edge provided with two nicks and the point P1 is about 1 mm, and the vertical line S3 on the rake face 5 side of the cutting edge provided with one nick. The vertical distance from the point P2 was about 2 mm.

Spindle speed: 320 rpm (cutting speed (V): 20 m / min), feed speed (f): 0.3 m
m / rev (96 mm / min). Spindle speed: 640 rpm (cutting speed (V): 40 m
/ Min), feed rate (f): 0.25 mm / rev
(160 mm / min). Spindle speed: 960 rpm (cutting speed (V): 60 m
/ Min), feed rate (f): 0.25 mm / rev
(240 mm / min).

As a result, it was confirmed that, under any of the cutting conditions (1) to (3), the chip was moderately １ ／ to の of the whole chip and had a twist as shown in FIG. In this processing, direct visual observation is dangerous and impossible. Therefore, when the chip or the finished surface after the processing is observed, there is no damage, and there is almost no damage on the inner surface of the drilled hole. On the other hand, in the comparative example having no concave portion, such twisted chips were hardly observed. In addition, scratches were observed on the inner surface of the perforated hole. These things are
This is to demonstrate the effect of the present invention.

[0026]

As is apparent from the above description, according to the indexable insert for a spade drill according to the present invention, when drilling a metal having a relatively low hardness, the outermost periphery which is elongated and straight and tends to be discharged. Since the chips to be cut at the cutting edge portion outside the nick on the side can be twisted, the chips can be cut at an appropriate length, and the chip handling property can be significantly improved. As a result, it is possible to prevent the chips from being entangled with the holder, prevent the machine from being stopped and prevent the chips from being damaged, and improve the processing efficiency and extend the life of the chips.

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment embodying a throwaway tip for a spade drill according to the present invention.

FIG. 2 is a view of the chip of FIG. 1 as viewed from the rake face side of a cutting blade having two nicks.

FIG. 3 is a view of the chip of FIG. 1 as viewed from the rake face side of a cutting blade where one nick is provided.

FIG. 4 is an enlarged view of a main part of FIG. 2;

FIG. 5 is an enlarged view of a main part of FIG. 3;

FIG. 6 is a sectional view taken along line AA of FIG. 4;

FIG. 7 is a sectional view taken along line BB of FIG. 4;

FIG. 8 is a sectional view taken along line CC of FIG. 4;

FIG. 9 is a view for explaining a state of each chip cut and discharged by the chip of FIG. 1, showing a state in which nicks are attached to a holder as viewed from the rake face side of two cutting blades.

FIG. 10 is a sectional view taken along line DD of FIG. 9;

FIG. 11 is a diagram showing a state where chips cut by the outer cutting edge of the outermost nick in FIG. 9 are twisted and discharged.

FIG. 12 is an external view of chips that have been twisted, separated, and discharged.

FIG. 13 is a view seen from a rake face illustrating a torsional action of a chip having a single nick and having a cutting edge cut on an outer peripheral side thereof.

FIG. 14 is a sectional view taken along line EE of FIG. 13;

FIG. 15 is a diagram of another embodiment viewed from the rake face side.

FIG. 16 is a diagram of another embodiment viewed from the rake face side.

FIG. 17 is a perspective view of a conventional throwaway tip for a spade drill.

FIG. 18 is a view for explaining a state in which chips to be cut at the outer peripheral portion of the tip cutting edge extend and are discharged when piercing with the tip of FIG. 17;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Indexable insert for spade drill 2,3 Tip cutting edge 4,5 Rake surface 6,7 Chip breaker 8,9,10 Nick 9,10 Nick on outermost peripheral side 14,15,24,34 Recess 16a, 18a, 26a , 36a Chip contact surface 16s, 18s, 26s, 36s Chip contact surface outer edge 17, 19 Outer edge of tip cutting edge K, K1, K2 Chip S1, S2, S3, S4 Vertical line

Claims (4)

[Claims] 1. A spade drill indexable insert in which a chip breaker is recessed along the left and right tip cutting edges and an appropriate number of nicks are provided on the left and right tip cutting edges, near the outer periphery of each rake face. For the part, a concave portion is provided continuously from the chip breaker to form a chip contact surface against which a chip cut by the tip cutting edge on the outer peripheral side from the outermost peripheral nick can collide, and an outer edge of the chip contact surface. But,
A throw-away insert for a spade drill, characterized in that it is connected in an arc shape or an inclined shape with respect to the tip cutting edge when viewed from the rake face side. 2. The chip contact surface includes a vertical line extending from a substantially center of a nick on the outermost peripheral side of the tip cutting edge to a rake surface substantially perpendicular to the tip cutting edge, and a tip extending from an outer peripheral edge of the tip cutting edge. The indexable insert for a spade drill according to claim 1, wherein the insert is provided substantially corresponding to a range sandwiched between a vertical line extending on a rake surface substantially perpendicular to the cutting edge. 3. The chip contact surface includes at least a vertical line extending from a substantially center of the nick on the outermost peripheral side of the tip cutting edge to a rake surface substantially perpendicular to the tip cutting edge, and an outer peripheral edge of the tip cutting edge. The indexable insert for a spade drill according to claim 1, wherein the insert is located in a range sandwiched by a vertical line extending on the rake surface substantially perpendicular to the leading edge cutting edge. 4. The indexable insert for a spade drill according to claim 1, wherein the outer edge of the chip contact surface is connected so that the vertical distance from the tip cutting edge becomes longer as approaching the outer peripheral cutting edge.