JP2702061B2 - Drill head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting blade for drilling a deep hole in a work material made of metal or the like, and more particularly to a drill head to which a replaceable throw-away tip is attached.

[0002]

2. Description of the Related Art A deep hole cutting drill using a throw-away tip is, for example, shown in FIG.
No. 5. Two throw-away tips are detachably attached to the tip of a drill head having a path for discharging dust inside. The end face of the drill head is flat in this example. There is a gourd-shaped hole in part of the end face. Other parts also have holes. A throw-away tip is attached to the side wall of the hole. More precisely, there is a mounting seat on the side wall of the hole, and the throw-away tip is screwed into the mounting seat. A guide pad is provided on the outer surface of the cylindrical drill body in the axial direction. Two of them are provided so that the central angle is 90 °. This makes it possible to keep the position of the drill head correctly in the already drilled hole. FIG. 9 shows the shape of the throw-away tip.

The throw-away tip used here has a substantially equilateral triangle shape, and the length of one side of the triangle is, for example, 15
mm. Strictly speaking, it is a hexagon because a triangle is slightly raised at the midpoint of the side. The ridges are symmetrical, and the lengths of the six sides are equal. The angle of the ridge is 16
It is about 5 to 170 degrees. The interior angle of the vertex of the triangle is 70
It is on the order of {-75}. 58-41515
The issue has two throw-away tips so that one side of the triangle is parallel to the end face. One is attached to the outer periphery of the drill head and one is attached to the center.

[0004] Since the throw-away tip rotates around the central axis, the metal surface can be scraped. The angle of inclination of the blade on the center side is called the inner cutting edge angle. The outward inclination of the blade is called the outer cutting edge angle. When an equilateral triangular tip is attached to the end face, if the sides are parallel to the metal surface, both the inner cutting edge angle β and the outer cutting angle α become θ. This does not cut the metal. In the above example, since the sides of the triangle are angled to have an obtuse angle of 165 ° to 170 °,
α + β = 15 ° to 10 ° can be set. Here, since the inner cutting edge angle and the outer cutting edge angle are made equal, α = β = approximately 7.5 ° to 5 °.

Japanese Patent Publication No. 61-40486 also proposes a throw-away tip having a triangular and slightly mountain-shaped side as shown in FIG. This throw-away tip forms a step in the thickness direction so that cutting chips can be divided more finely. The condition that α = β = 7.5 ° to 5 ° also holds here.

Japanese Unexamined Patent Publication (Kokai) No. 59-196107 has also been devised to provide a step in the thickness direction with a regular triangular-shaped throw-away tip as shown in FIG. Again, two throw-away tips are attached to the outer and center. Again, the inner cutting edge angle and the outer cutting edge angle are equal, and α = β = 7.5 ° to 5 °.

In such a structure for mounting the throw-away tip, α = β, so that the contact of the outer throw-away tip with the metal cut surface becomes a point contact. In this case, abrasion becomes remarkable when the inner peripheral surface of the metal is shaved. Therefore, it is conceivable to make the blade surface parallel to the axial direction.

Japanese Utility Model Application Laid-Open No. 2-53316 meets such a demand. One side of the square is cut into an asymmetric chevron. It is a pentagonal chip. The three interior angles on the upper side are 110 °, 140 °, and 110 °, respectively. FIG.
FIG. 0 and FIG. 11 show a chip of Japanese Utility Model Laid-Open No. 2-53316. The mountain top WVV is formed asymmetrically so that the length ratio WV: VU = 8: 3. In this example, a step is provided in the WV. The feature of the pentagonal tip is here, but another important point is that since the side WX is mounted parallel to the axis, the WX also contacts and grinds the inside of the metal hole. WX is mounted on the outer periphery of the drill head in a direction parallel to the axis. This is different from the one in FIG. 9 in which the portion protruding from the outer periphery is one point. Since the area in contact with the metal inner surface increases, more stable cutting can be performed.

WV is the outer cutting edge and VU is the inner cutting edge.
ZWVZ = α is the outer cutting edge angle, and ΔUVZ ′ = β is the inner cutting angle.

Since this tip is mounted so that the side WX faces in the axial direction, a straight line ZZ 'perpendicular to WX is parallel to the end face of the drill. With respect to WX, sides WV and VU can be set freely. Therefore, the inner cutting edge angle can be freely selected.

However, unlike the triangular chip, this chip has no rotational symmetry and can be used only once. The metal surface is cut at the top vertex WVU, but if it is worn, it will be discarded.

[0012]

The conventional throw-away insert has a disadvantage that the cutting blade surface is sharp and wear is remarkable. A long-life tip that is less prone to wear is desirable. Further, when a deep hole is drilled, it is desirable that there is a portion (such as the WX side in FIG. 10) in contact with the inner peripheral surface of the hole . Furthermore, it is preferable that it is rotationally symmetric and can be used many times by changing the blade surface. This is because the life can be extended twice or three times.

Another problem is the problem of the inner cutting edge angle β. In many cases, the throwaway tip is provided at the outside and the center. In the center part, a part of the cutting tool exists on the rotation center of the drill. Since this part does not rotate, it does not cut the metal. But because in the other portions metals Yuku been cut, so that the blade surface on the axis Yuku crushed residual protrusion of the metal. This is called interference. That is, in the cutting tool located on the central axis, a portion of the flank of the inner cutting edge that crushes the remaining convex portion of the metal on the central axis is referred to as an interference area.

The advance of the drill by one rotation is s. The eccentricity between the center of the blade and the center of rotation is ε. One rotation advance s
Is large, the portion that advances by squashing increases, and the interference area becomes wide. When the eccentricity ε is large, the crushing is reduced, so that the interference area is narrowed. Assuming that the inner cutting edge angle is β, a condition for preventing the occurrence of the interference region is given by ε / s ≧ 1 / 2π tanP (1). This is an equation that determines the range of ε / s by β. It is of course better that ε / s is wider. The smaller the inner cutting edge angle β, the less interference ε
/ S range becomes narrower. The larger the inner cutting edge angle β, the wider the range without interference. Then, is the larger the inner cutting edge angle β, the better? , And not the case say. If β is too large, a large amount of uncut portions is generated . Therefore, the value of β is desirably set to about 15 ° to 30 °. In particular, 30 ° is optimal. In the case of FIG. 9, the inner cutting edge angle β was 5 ° to 7.5 °. In the case of FIG. 10, the inner cutting edge angle β was 200.

[0015] The objects of the present invention can be summarized as follows. The blade surface itself has a long life. There should be multiple symmetry planes that can be used repeatedly by changing the plane. The inner cutting edge angle of the center blade is large. It should be about 15-30 degrees. There must be a cut plane parallel to the axial direction.

[0016]

According to the first aspect of the present invention ,
The drill head has at least the front end face of the cylindrical head body.
A also central side and the outer periphery side and the indexable same shape to drilling a deep hole is fixed to the workpiece to the same azimuth angle, respectively, each chip central side and the outer peripheral side, a 3-fold symmetry It is a hexagonal shape with short sides and long sides alternately provided,
With respect to three short sides of the six sides of the hexagonal shape , a margin is provided along the cutting edge line, which is an inclined surface or an arc surface having a width of 0.2 mm to 1 mm, and each chip has one margin.
Make sure that the short side is almost parallel to the center axis of the head body.
The chip on the center side is attached to the
One short side is located on the center axis of the head body.
It is characterized by that .

According to a second aspect of the present invention, there is provided the first aspect of the invention.
In the drill head, the inclined surface or the arc surface of the throw-away tip is formed so as to be inclined at about 1 ° to 6 ° with respect to a thickness direction line of the tip .
You .

[0018]

FIG. 1 is a plan view of a throw-away tip according to the present invention. The signs of A, B, C, D, E and F are given to the vertices of the chip. It has three-fold symmetry about O. Therefore, the extension lines of AB, CD and EF intersect at P, Q and R, and the triangle PQR is an equilateral triangle.

Similarly, the extension lines of BC, DE, and AF also form an equilateral triangle. Here, the long sides are AB, CD, and EF. This length is defined as n. Short side is BC, DE, FA
It is. This length is defined as m. Let h be the length of the perpendicular from the center O to the long side AB. The perpendicular from the center O to the short side BC is defined as k. There are two types of interior angles. ∠BAF = Ψ,
Let {CBA =}. Ψ is more than 120 ゜ and ゜ is 1
20 ° or less.

Since there is a three-fold symmetry, the short sides BC, DE,
When FA rotates by 120 °, they overlap each other. Similarly, when the long sides AB, CD, and EF are rotated 120 ° about the point O, they overlap each other. A margin m is provided on the short sides BC, DE, and FA. The margin will be described later.

First, the inner cutting edge angle β will be described. Since this throw-away tip has three-fold symmetry, it has an extremely excellent feature. Assume that one of the short sides is set in the axial direction. For example, suppose that the short side BC is made parallel to the axial direction of the head body of the drill head. Then short side BC
Is perpendicular to the top surface of the head body. This is parallel to the plane of the metal to be cut. The side AF is always 30 ° with respect to this plane. That is, the inner cutting edge angle β = 30 °. This is a general principle that does not depend on the lengths m and n of the long side and the short side and the interior angles Θ and Ψ. Proof can be made easily.

AF is obtained by rotating BC by 120 °. The top surface of the head main body is obtained by rotating the same straight line BC by 90 ° about O. Therefore, the AF makes an angle of 30 ° with the top surface. Therefore, the inner cutting edge angle is always 30 °. The angle of the inner cutting edge is 5 ° to 7.5 in the past.
{10}. He explained that they are too narrow and can cause interference. s
/ Ε <2π tanβ, but when the inner cutting edge angle β is small, the range of s / ε is narrowed. That is why the angle should be between 15 ° and 30 °. In the case of the present invention, as long as one of the short sides is made parallel to the axial direction, the inclination angle of the other short side can always be 30 °. 30 ° is the optimum value for the inner cutting edge angle.

Of course, make one of the short sides parallel to the axial direction
Instead , if this is inclined by x, the inner cutting edge angle β = 30
Can be -x. By changing the inclination angle x to 0-15 °, β = 30 ° to 15 ° can be achieved.

Although the chip is hexagonal, since it has three-fold symmetry, the degree of freedom of the parameter is three. One of these concerns dimensions. There are only two free parameters for angles and dimensional ratios.

The relation among m, n, h, k, Θ, Ψ is organized. The sum of the interior angles of the hexagon is 720 °, and Θ and Ψ
Is the interior angle included in each of the three hexagonal chips, so that Θ + Ψ = 240 ゜ (2) Two radii OA (= OC = OD), OB (= O
D = OF). This is OA = (h ² + k ² + 2h k cos Ψ) ^1/2 cosec Ψ (3) OB = (h ² + k ² + 2h k cos Θ) ^1/2 cosec Θ (4) The length m of the long side (AB, CD, EF) and the length n of the short side (BC, DE, FA) are as follows: m = h (cot （+ cotΨ) + k (cosecΘ + cosecΨ) (5) n = k (Cotｔ + cotΘ) + h (cosecΘ + cosecΨ) given by (6). Since the equations (2), (5), and (6) are obtained, the number of free parameters is three. However, since the same can be said whether the size is enlarged or reduced, the ratio k /
h is freely given as a parameter. The angle is one free parameter because the sum of Θ and 角度 is 240 °.

After all, the tip of the present invention can be specified by two parameters with respect to the ratio of sides and angles.
9 has one free parameter, and has a low degree of freedom.

Now, the margin, which is also a remarkable feature of the present invention. It is provided on the rake face side of the short sides BC, DE, and AF. Of course, it may be provided on the long sides AB, CD, and EF, but since it is the short side that contacts the inner side surface of the hole as a cutting blade, it is essential to provide it on the short side.

FIG. 2 is an enlarged cross-sectional view of an equivalent short side such as the side BC, DE, or FA, which is provided with a margin m.
The front side (rake face side) is LJKG. Point G is the cutting edge line, which cuts the metal. GHI is the flank. The clearance angle δ is an angle formed by the clearance surface HI with respect to the line MN in the thickness direction (perpendicular to JL and IT). δ is 10 ° ~
30 °. Here, δ = 16 °.

In the prior art, the point G, which is the cutting edge line, and the point I, which is the ridge line on the back surface, are connected by a straight line. For this purpose, the workpiece is cut only at point G. G point would immediately blunt Maro for. However, in the present invention, since there is a margin GH (m), points G to H come into contact with the workpiece. The width of the GH is about 0.2 to 1 mm (for example, 0.4
mm). The inclination angle θ of GH with respect to MN is, for example, 4
゜. This can be in the range of 1-6 °.

The margin m is provided on the short side to reinforce the cutting edge. Since the inclination angle θ of the margin m is in the same direction as the clearance angle δ, if the inclination angle θ is equal to the clearance angle, the margin can no longer be distinguished from the clearance surface HI. Therefore, θ <δ, but δ is about 10 ° to 30 °, so the upper limit of δ is 6 °. If the lower limit of δ is 0 °, there is no escape in this portion, so it is set to 1 ° or more. Keep away from the MN even a little. Thus, the inclination angle of the margin m is about 1 ° to 6 °.

As soon as the width of the margin m is O, the flank is the same as the conventional one whose flank follows the cutting edge line G.
If the margin width m is too large, there is no escape of the blade, so that the metal to be cut cannot be cut. Optimally, 0.
4 mm, but more generally m = 0.1-1 mm

[0032]

An example will be described. In the chip of FIG. 1, the thickness is 7.5 mm, and one side of the imaginary equilateral triangle PQR is 30 mm.
And The length k of the leg of the perpendicular line from the point O to the shorter side BC, DE, FA is 11 mm. h is 8.5 mm.
The long side n is 16 mm, and the short side m is 7 mm. Ψ = 13
8 ° and Θ = 102 °. A, C, and E are cusps and are R0.5. The other B, D and F are rounded to R1.6. Long side AB, C
The diameter (= 2h) of the inscribed circle of D and EF is 17 mm.

The same embodiment is shown in FIG.
mm, θ = 4 °, δ = 16 °. JK is a ridge for breaking the chips here, and the height of JK is 0.7 mm. FIG. 3 is a sectional view. FIG. 4 is a schematic perspective view. The same reference numerals are assigned to the same ridges and points as in FIG. The front surface (wider surface) of the chip 1 is the surface on the cutting side, that is, the rake surface 2. ABCDEF is a sharp ridge. That is, it is a cutting line. Of these, margins m are formed for short sides such as BC, DE, and FA. From this (rear), the flank faces (BB'CC ',
CC'D'D,..., AA'B'B) 3.4. The margin m is formed in a part of the flank 3. A bolt hole 5 is drilled in the center of the chip 1.

In the above, all the throw-away chips have been described. The throw-away tip is used by being fixed to the tip mounting plate with bolts. FIG. 5 shows that the throw-away tip 1 is attached to the tip mounting plate 6 with screws 7.
FIG. FIG. 6 is a front view of the same. The chip mounting plate 6 is an elongated plate-shaped member. In some cases, two or three throw-away tips are attached to one drill, but all of them are used in a state attached to the tip attachment plate 6. All chips have the same azimuth. And this throwaway chip 1
The side of the drill head body center axis (that is, the center of rotation)
When used as the inner blade located at
The center axis ZZ 'passes through the short side AF of the chip 1.
To the head body 9 . At the intersection Z, the linear velocity of the blade with respect to the metal becomes O, so that a problem of interference occurs.

The chip mounting plate has a recess 8 having a shape substantially equal to that of the chip. The chip fits perfectly into this. Then, the chip 1 is fixed by the screw 7. The chip 1 cannot be rotated because it is fitted in the recess 8.

The short side BC of this chip is inside the head body 9
It is fixed so as to be parallel to the center axis ZZ '. In this case, the inner cutting edge angle β always becomes 30 °. This is the optimal angle where interference does not easily occur. The outer cutting edge angle α is an angle that can be freely given. This is generally between 5 ° and 15 °. The inner cutting edge angle β may be 15 ° to 30 °. In order to deviate from 30 °, the shape of the depression 8 is changed so that the short side B
C must not be parallel to the central axis ZZ 'of the head body 9 .

FIGS. 7 and 8 show a state in which the chip 1 and the chip mounting plate 6 are actually mounted on the head body 9 of the drill head. This is an example of attaching three throwaway chips. The head body 9 is a cylindrical member and has a hollow portion 1.
There is 0, through which chips and oil pass.
The front end face of the drill head 9 has quadrant openings 11 and 12.
There is. Two places on the wall surface of the opening 12 are the chip mounting seat 13,
It is 14. This is the center axis Z of the head body 9.
A vertical wall parallel to Z '. A chip mounting seat 15 is also formed at one location on the wall surface of the opening 11.

The chip 1 is mounted on the chip mounting plate 6, and the mounting plate 6 is fixed to the chip mounting seats 13 to 15 by screws 16, 17, 18.

The chip of the chip mounting seat 13 of the most innermost is header
It is located on the central axis side of the metal body 9 and has the slowest linear velocity and proceeds near the center of the metal hole. This is called the center chip. The tip of the tip mounting seat 15 between the center side of the head main body 9 and the outer peripheral side has an intermediate linear velocity.
This is called an intermediate chip Δ. Outermost tip mounting seat 14
The tip has the highest linear velocity because the cutting edge contacts the inner peripheral surface of the hole of the metal to be cut . This is referred to as an outer peripheral chip Λ. center
The rotation speeds of the side chip Γ, the intermediate chip Δ, and the outer peripheral chip Λ are naturally the same. However, since the distance from the center axis line ZZ 'is different, the linear velocity is different.

Guide pads 19 and 20 parallel to the axial direction are fixed to the side surface of the head body 9 by screws. This is a member that contacts the inner surface of the hole when a deep hole is drilled in the metal.

The same chip is attached to the center chip Γ, the intermediate chip Δ, and the outer chip Λ so that they have the same orientation. Therefore, the outer cutting edge angle α and the inner cutting angle β are equal for the three chips. It is a hexagonal chip having a long side and a short side, both of which contribute to cutting. Head body
When the drill head is rotated about the center axis ZZ 'of the cutting edge 9, the trajectories of the cutting edges of the tips Γ, Δ, Λ are determined to overlap each other. Then, deep holes can be made in the metal without leaving any excess.

Since there is a margin m on the short side, the contact area between the cutting edge line and the metal hole is increased, and wear of the cutting edge is prevented.

Although the center tip 方向, the outer tip Λ, and the intermediate tip Δ appear to have opposite cutting edge directions, this is not the case. Since the drill rotates clockwise,
The center chip Γ and the outer chip Λ are fixed in the direction in which the rake face can be seen in FIG. The intermediate chip Δ has the rake face on the back side in FIG. That is, the intermediate tip Δ is the center tip Γ
And the outer peripheral side chip Λ is installed in the opposite direction. Therefore, the direction of the cutting edge looks opposite. If you look at the direction of rotation, you can see that it is facing the same direction.

In the outer peripheral side chip 側, the short side is the central axis Z.
Since it is parallel to Z ', the contact with the inner peripheral surface of the metal hole to be cut is not a point contact but a line contact. In this regard, it's the one in Fig. 9.
Is also better. This is because only a point contact is made at one corner of the chip.

The number of chips may be two. In this case, one outer peripheral chip is attached to one opening, and one central chip is attached to the other opening. When the drill is rotated, the trajectory of the outer peripheral tip and the trajectory of the central tip need only overlap.

[0046]

According to the present invention, each throw-away chip has three-fold symmetry and alternately has short sides and long sides.
Square in shape, the margin is an inclined surface or arcuate surface of the width of 0.2mm~1mm along the cutting edge line with <br/> the short side of three of the six sides of the hexagonal shape provided, the margin One short side provided with is almost parallel to the center axis of the head body
As a result, the contact area of the cutting edge with the cutting inner peripheral surface of the work material increases,
In addition, the cutting edge can be strengthened to reduce wear and damage of the cutting edge. The margin on the short side is determined by the cutting blade
It is the short side that comes into contact with the cutting inner peripheral surface of the work material,
This is because it is easier to wear than the long side. The inclined surface or
The arc surface is about 1 ゜ to 6 ゜ with respect to the thickness direction line of the chip
It is good to Each throw-away tip is paired three times.
Since there are three cutting blades with good nomenclature, loosen the screws and
Re-use by turning the cap 120 degrees and fixing it again
Yes, that is, can be used three times.

As described above, each chip has a margin.
One short side provided is almost parallel to the center axis of the head body
And attached to the head body
The other short side of the chip has a margin
Because it is located on the center axis,
The angle of the inner cutting edge is
The phenomenon in which the blade surface crushes the remaining convex part of the metal)
It is difficult to get an angle. In this case,
When one short side is parallel to the center axis of the head body
Means that the inner cutting edge angle is always 30 °,
It is most suitable as a rake angle, and the short side
Even if it is slightly tilted with respect to the center axis of the
If the angle is between 0 and 15 degrees,
Inner cutting edge angle.

As described above, the inner cutting edge angle of the center side tip is dried.
Because the angle can be set so that interference does not easily occur,
Head that receives a strong thrust load such as crushing
The tip of the insert on the center axis of the main body is dull and damaged
Can be prevented and the life can be extended. Also, the outer circumference
Side tip is mounted at the same azimuth as the center tip
The one short side with a margin is the head body
Is located almost parallel to the center axis of the workpiece.
The contact area with
It is possible to reduce the occurrence of abrasion and damage of the dies.

Further , the throw-away tip is attached to the head body.
When mounting on a chip, attach each chip to one short side.
Position it so that it is almost parallel to the center axis of the pad body.
The chip can be positioned easily,
Can be easily mounted.

[Brief description of the drawings]

FIG. 1 is a plan view of a throw-away tip of the present invention.

FIG. 2 is an enlarged sectional view of a short side of the throw-away tip of the present invention.

FIG. 3 is a cross-sectional view passing through a bolt hole of the throw-away tip of the present invention.

FIG. 4 is a perspective view of the throw-away tip of the present invention.

FIG. 5 is a plan view showing a state in which the throw-away tip is attached to a tip attachment plate.

FIG. 6 is a front view showing a state in which the throw-away tip is attached to a tip attachment plate.

FIG. 7 is a plan view of a tip mounted on a drill head.

FIG. 8 is a front view of a state where the tip is attached to a drill head.

FIG. 9 is a front view of a triangular throw-away tip according to a known example.

FIG. 10 is a front view of a pentagonal throwaway tip according to a known example.

FIG. 11 is a perspective view of a pentagonal throw-away tip according to a known example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 throw-away tip 2 rake face 3 flank face 4 flank face 5 bolt hole 6 chip mounting plate 7 screw 8 dent 9 head body 10 cavity 11 opening 12 opening 13 chip mounting seat 14 chip mounting seat 15 chip mounting seat m margin

Claims (2)

(57) [Claims] 1. At least a front end face of a cylindrical head body.
A also central side and the outer periphery side and the indexable same shape to drilling a deep hole is fixed to the workpiece to the same azimuth angle, respectively, each chip central side and the outer peripheral side, a 3-fold symmetry It is a hexagonal shape with short sides and long sides alternately provided,
With respect to three short sides of the six sides of the hexagonal shape , a margin is provided along the cutting edge line, which is an inclined surface or an arc surface having a width of 0.2 mm to 1 mm, and each chip has one margin.
Attached to the head body so that the short sides are almost parallel
And the other short side of the center chip is the head body.
A drill head that is positioned on the center axis . 2. The drill head according to claim 1, wherein the inclined surface or the arc surface of the throw-away tip is formed to be inclined at about 1 ° to 6 ° with respect to a thickness direction line of the tip .