JP2003145320A - Throwaway tip, and clamp mechanism for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly position a cutting edge 5 to improve tip installation rigidity without applying high precision polishing work to a rear end part 7 of a throwaway tip 3 or a receiving part 14 of a tip installation seat 2. SOLUTION: A cutting edge 5 is formed on the tip side of a tip body 6 in a flat form in this throwaway tip 3, it is inserted into the tip installation seat 2 on a tool body 1 to be pressed to the rear end side by a pressure means 4, and the rear end part 7 is abutted on the receiving part 14, and installed detachably. In the tip body 6, an installation hole 12 to be engaged with the pressure means 4 to receive pressure toward the rear end side, and an inner circumferential rear end side part of the installation hole 12 is formed in a recessed V-form recessed toward the rear end side. The pressure means 4 is provided with a pressure part 26 having a circular cross section to be abutted on a pair of wall surfaces 13 and 13 forming the recessed V-form of the inner circumferential rear end side part of the installation hole 12 to press the tip body 6 to the rear end side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away tip (hereinafter referred to as a tip) suitable for a throw-away type ball end mill, and a clamp mechanism therefor.

[0002]

2. Description of the Related Art A ball end mill equipped with a chip of this type and a clamp mechanism therefor is disclosed in, for example, Japanese Patent Laid-Open No. 8-
In Japanese Patent No. 252714, a groove bottom surface of a concave groove-shaped tip mounting seat formed at the tip of a tool body of a ball end mill is formed on a tip receiving surface which is recessed in an arc shape centered on the central axis of the tool body. At the same time, the rear end of the tip body provided with an arcuate cutting edge on the tip side is an arc-shaped protrusion having a radius of curvature equal to or greater than the radius of curvature of the arc of the receiving surface, and this rear end is It is proposed that a chip is attached by pressing it against a chip receiving surface. Here, in the pressing means for pressing the rear end portion of the chip toward the receiving surface side of the chip mounting seat, that is, the rear end side, the circular body portion is inserted into the mounting hole formed in the chip body and clamped. A screw is screwed into the tool body, and the conical surface of the head of the clamp screw is applied to the eccentric cone receiving surface of the tool body to bend the clamp screw. The chip is pressed against the receiving surface.

[0003]

By the way, in such a conventional chip and its clamp mechanism, in the above-mentioned pressing means, the circular body of the clamp screw has only one point on the rear end side of the inner periphery of the mounting hole of the chip body. Then, the pressing force acts on one straight line passing through this one point and the tip is pressed toward the rear end side (receiving surface side), while the rear end portion of this chip and the above receiving surface are When the radius of curvature of the rear end is equal to that of the receiving surface, surface contact is made along the arc of the radius of curvature, and when the radius of curvature of the rear end is larger than that of the receiving surface, two-point contact is made. Therefore, the contact surface or contact point is exactly symmetrical with respect to the straight line on which the pressing force acts, so that the arcuate projection of the rear end of the chip body or the arcuate recess of the chip mounting seat is received. If the surface is not formed, the attachment of the tip becomes unstable and the position of the cutting edge shifts, making it impossible to form a highly accurate machined surface especially in the finishing process, but the arc-shaped protrusion In order to accurately form the tip and the receiving surface in such a manner, it is necessary to form the tip body and the tool body and then to polish the above-mentioned projection and the receiving surface with high precision, which is often required for manufacturing these. It takes time and labor and results in high cost.

Further, as described above, the tip is held only by the arc-shaped projection at the rear end of the tip and the arc-shaped recessed portion of the tip mounting seat making surface contact or two-point contact. In the case of surface contact, along the arc of the above-mentioned radius of curvature, and also in the case of two-point contact, along the arc connecting these points, excessive load or impact load acts on the chip body during processing. In this case, the chip body may rotate around the point where the inner periphery of the mounting hole and the circular body contact with each other in the direction in which these loads act against the pressing force of the pressing means. Therefore, it is impossible to obtain high precision in finishing.

The present invention has been made under such a background, and the cutting edge can be accurately positioned without polishing the tip rear end portion or the receiving surface of the tip mounting seat with high precision. It is an object of the present invention to provide a chip and a clamp mechanism therefor capable of improving the mounting rigidity of the chip.

[0006]

In order to solve the above problems and to achieve such an object, the tip of the present invention has a cutting edge formed on the tip side of a flat plate-like tip body, Is inserted into the tip mounting seat formed in the tool body and is pressed to the rear end side by the pressing means provided in the tool body, so that the rear end part of the chip body comes into contact with the receiving part of the chip mounting seat. A chip that is detachably attached to the chip attachment seat, wherein the chip body is
A mounting hole which engages with the pressing means and receives a pressing force toward the rear end side is formed, and the mounting hole has a concave V shape in which the rear end side portion of the inner periphery is recessed toward the rear end side. It is characterized by that. Further, the clamp mechanism of the present invention inserts the tip thus configured into the tip mounting seat formed in the tool body, and presses it toward the rear end side by the pressing means provided in the tool body. A chip clamping mechanism for removably attaching to the receiving portion of the chip mounting seat so that the rear end portion of the chip main body is brought into contact with the receiving portion of the chip mounting seat, wherein the pressing means has a mounting hole for the chip body. A pressing portion having a circular cross section, which is inserted into and engaged with, and abuts against the pair of concave V-shaped wall surfaces of the rear end side portion of the inner periphery of the mounting hole to press the chip body toward the rear end side. It is characterized by having.

Therefore, in the chip having such a structure, the rear end side of the inner peripheral portion of the mounting hole of the chip body is formed into a concave V-shape which is recessed toward the rear end side. The pressing portions having a circular cross section (for example, the circular body portion of the clamp screw) are respectively brought into contact with the pair of wall surfaces of the inner peripheral rear end portion of the concave V-shape, that is, the inner peripheral surface of the mounting hole and the pressing portion. Are brought into contact with each other at two points, and a pressing force acts from these two points toward the rear end side in a direction in which they are separated from each other. Therefore, it is possible to improve the mounting rigidity of the chip by increasing the number of contact points between the chip and the pressing portion, and of course, the pressing portion is in contact with the concave V-shaped wall surface of the inner periphery of the mounting hole in this way, and the chip main body. By pressing, the chip is positioned so that the concave V-shaped bisector formed by the pair of wall surfaces passes through the center of the circle formed by the cross section along the pressing direction of the pressing portion. Even if you do not perform arc-shaped high-precision polishing on the rear end of the chip body and the receiving surface of the chip mounting seat as in the past,
It is possible to accurately clamp the chip at a predetermined position.

Further, in the above-mentioned chip, since the pressing portion abuts against the pair of concave V-shaped wall surfaces on the rear end side of the inner periphery of the mounting hole to position the chip main body, the rear end portion of the chip main body is positioned. Is formed in a direction extending perpendicular to the concave V-shaped bisector formed by the rear end side portion of the inner periphery of the mounting hole, the chip body can be positioned more smoothly and with high accuracy. At the same time, the formation of the rear end portion can be further facilitated, and further cost reduction of the chip can be promoted. On the other hand, in the clamp mechanism, the receiving portion of the tip mounting seat is provided between the rear end portion of the tip body and the concave V-shaped bisector formed by the rear end portion of the inner periphery of the mounting hole. By forming the gap so as to define the gap, it is possible to further facilitate the formation of the receiving portion and the rear end portion of the chip body, and the rear end portion of the chip body and the receiving portion on both sides of the gap portion. The chip is supported at three points, that is, the abutting part of the chip and the pressing part that abuts on the rear end side portion of the inner periphery of the mounting hole via the pair of wall surfaces, so that the mounting stability of the chip can be secured. .

Furthermore, such a tip and its clamping mechanism are particularly effective when applied to the above-mentioned throw-away type ball end mill in which the tip is required to have high positioning accuracy and mounting rigidity. The cutting edge has a substantially arcuate shape, and the tool body has a substantially columnar shape centered on the axis rotated about the axis. The tip mounting seat is provided at the tip of the tool body. Is formed in the shape of a groove that is recessed along the axis, and it is suitable when the receiving portion of the chip mounting seat with which the rear end of the chip body abuts is formed on the groove bottom surface of the groove. . Further, in this case, in the tip, the center of the arc of the cutting edge having a substantially arc shape is arranged on the concave V-shaped bisector formed by the rear end side portion of the inner periphery of the mounting hole. And in the clamp mechanism, the pressing means can press the mounting hole of the chip body toward the rear end side along the axis, so that the center of the arc formed by the cutting edge is used as a tool. The chip can be clamped by being accurately positioned on the axis of the main body, and it becomes possible to perform processing with higher accuracy.

[0010]

1 to 8 show a throw-away type ball end mill equipped with a tip and a clamp mechanism thereof according to an embodiment of the present invention. In this embodiment, the tool body 1 has a front end side (left side in FIGS. 1, 2, 4, 5, 7, and 8) as a rear end side (FIGS. 1, 2, 4, 5, 7, and 8) as shown in FIG. (Right side in Fig. 2), it has a multi-stage cylindrical shape centered on an axis O having a diameter smaller than that of the tip mounting seat 2 having a grooved shape which is recessed along the axis O toward the rear end. 2 is formed, the tip mounting seat 2 has a U-shaped cross-section that opens to the tip end surface of the tool body 1 as shown in FIG. 2 in a side view of the tool body 1. The tip mounting seat 2 is shown in FIG.
Or a chip 3 as shown in FIG. 6 is inserted, and a clamp screw 4 as a pressing means of the present embodiment is screwed into the tip end portion of the tool body 1 to be removably attached to the tip mounting seat 2. The ball end mill is a cutting blade formed on the tip side of the tip 3 by feeding the tool body 1 with the tip 3 attached thereto in a direction intersecting the axis O while rotating in the tool rotation direction T around the axis O. Cut the work piece by 5.

The tip body 3 of the tip 3 is formed by a hard material such as cemented carbide into a flat plate shape having a semi-cylindrical shape as shown in FIG. In a state where the tool body 1 is attached to the tool body (hereinafter referred to as a tip attachment state), as shown in FIGS. Further, of the peripheral surface portion of the tip body 6 located between the pair of side surfaces, a rear end portion (a portion corresponding to the plate bottom of the above-mentioned kamaboko-shaped kamaboko plate) which faces the rear end side of the tool body 1 in the above-mentioned chip attachment state. Is formed so as to extend linearly in the plan view in a direction orthogonal to the axis O in the chip mounted state, and
The semi-arcuate portion on the front end side excluding the rear end portion 7 and the portion that is in contact with the semi-circular arc portion from both ends of the semi-circular arc portion and is orthogonal to the rear end portion 7 are cut into the above-mentioned cuts. The blade 5 is formed.

Here, in the pair of side surfaces of the tip body 6 which are in the shape of a kamaboko, the flat surfaces 8 are parallel to each other except for the peripheral portion on the side facing the tool rotation direction T. The tool rotation direction T
The peripheral portion facing toward is a sloped surface 9 that is gradually recessed at a constant slope angle with respect to the flat surface 8 as it goes toward the axis O side (the inner peripheral side of the tool body 1) in the state where the chip is attached, and The inclined surfaces 9, 9 are located on one plane including the axis O. Then, in the tip 3 of the present embodiment, the peripheral edges of the inclined surfaces 9 and 9 are the cutting edges 5, and the cutting edges 5 and 5 formed on the peripheral edges of the inclined surfaces 9 and 9 are 1 has a semi-circular shape on the plane thereof, and the tip inner peripheral side end of the tool body 1 is aligned on the axis O in the tip mounted state. The rotation loci of the blades 5 and 5 around the axis O are formed into a hemisphere having a center on the axis O. Further, the inclined surfaces 9 and 9 are used as the rake surface of the cutting blades 5 and 5, and
The peripheral surface portions of the tip body 6 extending from the cutting blades 5, 5 to the rear side in the tool rotation direction T in the attached state are the flanks of the cutting blades 5, 5 respectively. As it goes toward the rear side of T, it is inclined so as to recede inside the hemisphere formed by the rotation locus.

The portion of the side surface of the chip body 6 extending from the flat surface 8 to the inclined surface 9 is the flat surface 8
Further, the breaker wall surface 10 intersects the inclined surface 9 at an obtuse angle and gradually rises from the inclined surface 9 which is a rake surface toward the center side of the hemisphere. Further, in the tip 3 of the present embodiment, the cutting edge tip 1 made of an ultra-high hardness sintered body such as a diamond sintered body or a CBN sintered body is provided on the peripheral portion of the inclined surface 9 on which the cutting blade 5 is formed.
1 is brazed and joined, and the cutting edge 5 is formed on this cutting edge tip 11. Further, the rear end 7
Of these, the central portion in the thickness direction (vertical direction in FIGS. 5 and 6) of the chip body 6 is a plane orthogonal to the axis O in the chip mounting state, and the flat surface of the plane and both side surfaces of the chip body 6 are flat. The ridge line part intersecting with the faces 8 and 8 is
The flat surfaces 8 and 8 are chamfered so as to intersect with each other at an obtuse angle.

Further, mounting holes 12 are formed in the central portions of the both side surfaces of the chip body 6 so as to penetrate between the flat surfaces 8 in the thickness direction. As shown in FIGS. 4 and 7, in the cross section orthogonal to the thickness direction, the front end side portion of the inner peripheral portion thereof has a substantially semicircular shape, while the rear end side portion is the rear end side of the chip body 6. It has a concave V shape that is recessed toward. Here, in the chip 3 of the present embodiment, the mounting hole 12 has the flat surface 8,
8 is formed perpendicular to 8 along the thickness direction with a constant cross-sectional shape and size, and as shown in FIG.
The center X of the semicircle formed by the portion on the tip side of the inner circumference of the tool is made to coincide with the center of the hemisphere formed by the rotation locus of the cutting blade 5 located on the axis O of the tool body 1. The concave V-shape formed by the rear end side portion of the inner periphery of the mounting hole 12 is such that the bisectors of the pair of wall surfaces 13, 13 approaching each other toward the rear end side forming the V-shape coincide with the axis O. Has been

Therefore, the rear end portion 7 of the chip body 6 formed in a straight line in the direction extending orthogonally to the axis O is
Even with respect to the bisector, it is formed in a straight line in a direction extending orthogonally in the plan view, and the centers of the cutting blades 5 and 5 having a semi-arcuate shape are also formed on the inner circumference of the mounting hole 12. The center of the semicircle on the tip side is aligned with the center of the semicircle, and the semicircle is arranged on the bisector. In addition, this pair of wall surfaces 1
The included angle θ of the concave V-shape formed by 3 and 13 is 90 to 120 °.
It is desirable to set it in the range of 10 in this embodiment.
It is set to 0 °. The distance from the center X of the semicircle to the wall surfaces 13, 13 in the direction perpendicular to the wall surfaces 13, 13 is slightly larger than the radius of the semicircle.
Further, on the inner peripheral rear end side of the mounting hole 12, these wall surfaces 1
The part where 3 and 13 intersect with each other and the part where the wall surfaces 13 and 13 intersect with the semicircular part on the inner peripheral tip side of the mounting hole 12
The wall surfaces 13 and 13 are connected to each other or the wall surface 13 and the semicircular portion are connected in an arc shape in cross section so as to be in smooth contact with each other.

On the other hand, the concave groove-shaped tip mounting seat 2 to which such a tip 3 is mounted is formed so as to cut out the tip end portion of the tool body 1 in the diameter direction with respect to the axis O, and The rear end portion 7 of the chip body 6 is provided on the bottom surface of the groove.
A chip receiving portion 14 is formed so as to abut.
However, on the bottom surface of the groove, the diametrically opposite ends are formed in a plane shape orthogonal to the axis O, and the plane portions of the rear end portion 7 can come into contact with the chip receiving portions 14, 14.
In contrast to these, these chip receiving parts 14, 1
The portion on the axis O between the four is formed in a concave arc shape which is recessed toward the rear end side toward the side of the axis O, whereby the portion on the axis O in the mounted state of the chip, that is, the above-mentioned mounting of the chip 3 is performed. A gap C is formed between the flat portion of the rear end portion 7 of the chip body 6 at the portion on the bisector of the concave V formed by the rear end side portion of the inner periphery of the hole 12. Further, a pair of groove wall surfaces facing each other of the groove extending to the tip side crossing the groove bottom surface are parallel to each other and parallel to the axis O and are equally spaced from the axis O. Is sized so that the chip 3 can be inserted into the chip mounting seat 2 in a state where the flat surfaces 8 on both side surfaces of the chip body 6 are in close contact with these wall surfaces.

Further, a clamp screw hole 15 into which the above-mentioned clamp screw 4 as a pressing means is screwed is formed at the tip of the tool body 1 so as to be orthogonal to the groove wall surfaces of the concave groove formed by the chip mounting seat 2. An insertion hole 16 through which the clamp screw 4 is inserted is formed. Of these, the clamp screw hole 15 is configured such that the chip 3 is inserted into the chip mounting seat 2 by aligning the concave V-shaped bisector of the inner peripheral portion rear end side of the mounting hole 12 with the axis O as described above. With the rear end portion 7 in contact with the chip receiving portions 14, 14, the clamp screw hole 15
The center line L of the chip body 6 in the thickness direction of the chip body 6
2 is formed so as to pass through the center X and orthogonal to the axis O, and penetrates from one groove wall surface of the pair of groove wall surfaces perpendicularly to the groove wall surface to the outer periphery of the tip of the tool body 1. And a female screw portion 17 is formed on the outer peripheral side of the tip portion of the tool body 1, and the one groove wall surface side has a diameter slightly larger than the female screw portion 17,
A round hole portion 18 having substantially the same diameter as the semicircle formed by the tip of the inner peripheral portion of the mounting hole 12 is formed.

Further, the insertion hole 16 is formed so as to penetrate from the other groove wall surface of the pair of groove wall surfaces to the outer periphery of the tip portion of the tool body 1 also perpendicularly to the groove wall surface, and the other groove wall surface. The side is a circular hole portion 19 which is coaxial with the center line L of the clamp screw hole 15 and has the same diameter as the circular hole portion 18, and the outer peripheral side of the tip of the tool body 1 is gradually expanded toward the opening side. A tapered portion 20 having a diameter is formed. The center line of the tapered portion 20 is located slightly rearward of the center line L of the clamp screw hole 15 and extends parallel to the center line L in a direction orthogonal to the axis O. As described above, the center line L is eccentric. In addition, between the other groove wall surface of the chip mounting seat 2 in which the insertion hole 16 is formed and the groove bottom surface in which the chip receiving portion 14 is formed, the other one of the other surfaces is formed from the groove bottom surface toward the rear end side. A slit 21 is formed along the groove wall surface. Further, on the outer periphery of the tip end of the tool body 1, chip pockets 22 and 22 having a concave curved section that is recessed so as to be substantially continuous with the breaker wall surface 10 of the tip body 6, are formed from the tip of the tool body 1 in the form of grooves. The mounting seat 2 is formed so as to extend toward the side where the cutting edge 5 is formed on both side surfaces of the chip 3 along the edge of the opening.

Further, the clamp screw 4 which is inserted into the insertion hole 16 and screwed into the clamp screw hole 15 has a male screw portion 23 which is screwed into the female screw portion 17 at one end and the other end at the other end. Has a head portion 24, and the surface of the head portion 24 facing the one end side is the tapered portion 2
The taper surface 25 has a taper angle equal to 0 and gradually expands toward the other end. Then, between the male screw portion 23 and the head portion 24, a cylindrical body portion 26 having a circular cross section is formed coaxially with the male screw portion 23 and the head portion 24. It is a pressing portion in the embodiment. The length of the circular body portion 26 is set within the range from the round hole portion 18 of the clamp screw hole 15 through the mounting hole 12 of the chip 3 to the round hole portion 19 of the insertion hole 16 in the chip mounting state. As well as
The radius is smaller than the radius of the round holes 18 and 19 or the radius of the semicircle formed by the inner peripheral tip side portion of the mounting hole 12 of the chip 3, and the center of the semicircle of the inner peripheral tip side portion of the mounting hole 12. The wall surfaces 1 and 1 forming a concave V-shape on the rear end side of the inner circumference from X
3 is substantially equal to or slightly smaller than the distance to the tip 3, and the tip 3 is mounted on the tip mounting seat 2 as described above.
And the rear end portion 7 is brought into contact with the chip receiving portions 14 and 14, and then the male screw portion 23 of the clamp screw 4 is screwed into the female screw portion 17 to make the taper surface 25 of the head portion 24.
Is in a state before contacting the tapered portion 20 of the insertion hole 16, the outer peripheral surface of the circular body portion 26 is the wall surface 13 of the mounting hole 12,
It is said that it is lightly contacted with 13.

Therefore, in the chip 3 and the clamp mechanism thereof configured as described above, the clamp screw 4 is further screwed in from this state to bring the taper surface 25 of the head portion 24 into contact with the taper portion 20 of the insertion hole 16. By pressing the tip mounting seat 2 in the thickness direction, the tip body 6 is sandwiched by the tip end portion of the tool body 1 which is divided into two by the groove mounting tip 2 so that the tip mounting seat 2 has the above-mentioned shape. The flat surfaces 8 on both side surfaces of the chip body 6 are pressed and pressed by the pair of groove wall surfaces. On the other hand, since the center line of the tapered portion 20 of the insertion hole 16 is eccentric from the center line L of the clamp screw hole 15 toward the rear end side, the tapered surface 25 of the head portion 24 of the clamp screw 4 has a tapered surface 25 of the insertion hole 16. The tip end portion of the taper portion 20 is brought into contact with and pressed against this portion. Due to the reaction force, the other end side of the clamp screw 4 itself on which the head portion 23 is formed is slightly bent toward the rear end side of the tool body 1, Accordingly, the circular body portion 26 as a pressing portion also bends toward the rear end side in the direction of the axis O, and the outer peripheral surface presses the inner peripheral rear end side portion of the mounting hole 12 of the chip body 6 toward the rear end side,
As a result, the chip 3 is also pushed toward the rear end side, so that the rear end portion 7 of the chip body 6 that is brought into contact with the chip receiving portions 14 and 14 on the groove bottom surface of the chip mounting seat 2 receives the receiving portions 14 and 14.
The chip 3 is clamped and attached to the chip mounting seat 2 by these.

However, in the chip 3 having the above-mentioned structure, the rear end side portion of the inner periphery of the mounting hole 12 pressed by the circular body portion 26 as the pressing portion is formed in a concave V shape which is recessed toward the rear end side. Therefore, the circular body portion 26 comes into contact with the inner peripheral rear end side portion of the mounting hole 12 at two points on each of the wall surfaces 13 forming the concave V-shape. For this reason, first, the number of contact points between the circular body portion 26 and the inner periphery of the mounting hole 12 is increased and the circular body portion 26 is increased as compared with the conventional case where the pressing portion and the inner periphery of the mounting hole are in contact with each other at only one point. From the above wall 13,1
The pressing force acting on 3 does not act on one straight line from the above-mentioned one point as in the conventional case, but the direction of separating from the two contact points of the wall surfaces 13 and 13 and the circular body 26 toward the rear end side. Since it acts in two directions toward, it is possible to improve the mounting rigidity of the tip 3 to the tip mounting seat 2, and the tip 3 may move during cutting and the processing accuracy may be impaired. It is possible to prevent such a situation.

Further, in the tip 3 and the clamp mechanism thereof having the above-mentioned constitution, the rear end side portion of the inner periphery of the mounting hole 12 is formed in the concave V shape, and the pressing force by the circular body portion 26 is applied to the wall surfaces 13 and 13. By acting in two directions from the two contact points with the chip 3, the chip 3 is moved to these wall surfaces 13, 1
3 is pushed and moved by the circular body 26 so as to be pressed uniformly, so that the concave V-shaped bisector formed by the rear end side portion of the inner periphery of the mounting hole 12, that is, the bisector of the wall surfaces 13 and 13 described above. However, the tip 3 is positioned so as to match the direction in which the tip 3 is pressed by the pressing means through the center of the circular body portion 26, that is, the direction toward the rear end side of the tool body 1 along the axis O. Therefore, it is not necessary to grind both the rear end portion and the receiving surface with high precision as in the case of securing the positioning accuracy of the tip between the rear end portion of the conventional chip body and the receiving surface side of the chip mounting seat. As a result, the time and labor required for manufacturing the tip 3 and the tool body 1 can be reduced, while the tip 3 can be accurately arranged at a predetermined position, which results in low cost and low positioning accuracy. It becomes possible to provide the high tip 3 and its clamp mechanism.

In this way, the chip 3 is thus divided into two halves of a concave V shape formed by the rear end side portion of the inner periphery of the mounting hole 12 regardless of the molding precision of the rear end portion and the chip receiving surface as in the conventional case. By positioning by the line, according to the chip 3 having the above-described configuration, the rear end portion 7 of the chip body 6 extends orthogonally to the bisector, which is the easiest to mold, as in the present embodiment. Can be formed in any direction. Therefore, tip 3
Cheaper chip 3 to further reduce manufacturing cost
And the rear end portion 7 of the tip body 6 extends in the direction orthogonal to the bisector, so that the bisector coincides with the axis of the tool body 1 as described above. As described above, it becomes possible to smoothly move the chip body 6 when it is pushed, and the positioning accuracy of the chip 3 can be improved. Further, particularly when the rear end portion 7 of the chip body 6 is formed in a straight line extending in the direction orthogonal to the bisector in the plan view as in the present embodiment, an excessive load or load is applied to the chip body 6 during processing. Even when an impact load is applied, the tip body does not rotate and deviate as in the case of a conventional tip having a rear end portion formed into an arcuate projection.

On the other hand, in the ball end mill equipped with the clamp mechanism of this embodiment, the tip receiving portions 14, 14 with which the rear end portion 7 of the tip 3 abuts on the tip mounting seat 2 at the tip of the tool body 1. However, by denting the portion of the groove bottom surface of the chip mounting seat 2 on the axis O on the rear end side, a halving of a concave V-shape formed by the inner peripheral rear end portion of the mounting hole 12 of the chip 3 is formed. The portion C on the line is formed so as to define a gap C with the flat portion of the rear end portion 7. For this reason, the entire bottom surface of the groove is set at the rear end portion 7 of the chip 3.
The tip mounting seat 2 can be formed more easily and the manufacturing cost of the tool body 1 can be reduced as compared with the case where the tip mounting seat 2 is formed so as to surely come into close contact with the flat surface portion. Further, by defining the gap C in this way, the rear end portion 7 of the chip 3 and the chip receiving portion 14 of the chip mounting seat 2 are formed.
Although the contact area itself with the clamp screw 4 decreases, the pressing force exerted by the circular body portion 26 of the clamp screw 4 on the chip body 6 from the wall surfaces 13 and 13 in the two directions separating from each other toward the rear end side is the two directions. It is received by the chip receiving portions 14, 14 of the chip mounting seat 2 arranged above, and the circular body portion 26 as a pressing portion, the rear end portion 7 of the chip 3 and the chip receiving portions 14, 14 are received. Since the chip body 6 is supported at three points with the abutting part of, that is, the chip 3 is attached by three-point support by an isosceles triangle symmetrically arranged with respect to the axis O, The mounting stability of the chip 3 is not impaired, and the chip mounting rigidity can be improved as described above. When defining the gap C in this way, in addition to recessing the groove bottom surface of the chip mounting seat 2 as in the present embodiment, the rear end portion 7 of the chip 3 is recessed on the above bisector. However, the groove bottom surface may be flat, or both the groove bottom surface and the rear end portion 7 may be recessed.

Therefore, the chip 3 configured as described above
And since the clamping mechanism for the chip 3 can improve the mounting rigidity and the positioning accuracy of the chip 3 and secure the mounting stability in this way, the chip 3 is not cut like the present embodiment. The blades 5 and 5 are formed in a substantially arc shape, while the tool body 1 is formed into a substantially cylindrical shape centered on the axis O rotated about the axis O, and the tip is attached to the tip of the tool body 1. The mounting seat 2 is formed in the shape of a groove that is recessed along the axis O, and the rear end portion 7 of the chip body 6 abuts on the groove bottom surface of this groove 1
4 and 14, that is, it is more effective when the above configuration is applied to the insert of the throw-away type ball end mill and its clamp mechanism.

Particularly, in the tip 3, the center of the cutting blades 5, 5 having an arc shape, that is, the center of the hemisphere formed by the rotation loci of the cutting blades 5, 5 is set to the tip body 6 as described above.
Center X of the tip side portion forming a semicircular cross section of the inner periphery of the mounting hole 12 of
The clamp screw 4 as a pressing means in the clamp mechanism along the axis O by arranging the clamp screw 4 as the pressing means in the clamp mechanism. By bending the mounting hole 12 of the chip body 6 toward the rear end along the axis O by the circular body 26 as the pressing portion. Since the centers of the cutting blades 5, 5 can be accurately positioned on the axis of the tool body 1 by the above-described positioning action due to the contact with the wall surfaces 13, 13 having a character, even if the ball end mill has higher positioning accuracy. It is possible to surely satisfy such a requirement even for a finish for which mounting rigidity is required. In this way, in the tip 3 detachably attached to the tool body 1 by the clamp mechanism, in order to accurately arrange the center of the arcuate cutting edge on the above-mentioned bisector, that is, the axis O, the tip 3 is With the tool body 1 clamped,
The cutting edges 5 and 5 may be sharpened and formed.

By the way, in this embodiment, the wall surface 13,
Angle V of the concave V-shape on the rear end side of the inner circumference of the mounting hole 12 by 13
However, if the included angle θ is too large, the direction of the pressing force acting on the wall surfaces 13 becomes close to parallel, which is the case when the pressing force acts on one point in the conventional case. There is a possibility that it will not change and the above-mentioned effects will not be sufficiently achieved. On the other hand, conversely, if the included angle θ of the wall surfaces 13, 13 is too small, the wall surfaces 13, 13
The pressing force acting on the chip 3 does not press the tip 3 toward the rear end side, but strongly acts in the direction of expanding the wall surfaces 13 and 13, and of course the mounting strength of the chip 3 is impaired, and in some cases, There is a possibility that a crack may occur in the chip body 6 from the bottom of the concave V-shape. For this reason,
The included angle θ is preferably set in the range of 90 to 120 ° as in the present embodiment.

Further, in the chip 3 of this embodiment, the inner periphery of the mounting hole 12 is formed in a concave V shape on the rear end side, while the front end side is substantially semicircular, but the rear end side is concave. The shape of the tip side is not limited as long as it is formed in a V shape,
For example, the cross section of the mounting hole 12 may be formed in a triangular shape having a concave V-shaped portion that is recessed toward the rear end side, a quadrilateral shape such as a rhombus, or a square shape. Further, although the tip and the clamp mechanism thereof having the above-mentioned configuration are effective when applied to the throw-away type ball end mill as described above, they are applied to the tip and the clamp mechanism of the throw-away type cutting tool other than this. Of course, it is possible.

[0029]

As described above, according to the tip and the clamp mechanism of the present invention, it is easy to form the tip mounting seat of the tip body or the tool body to reduce the cost, but the tip is high. Positioning accuracy and mounting rigidity can be provided, and in particular, the present invention can be applied to a throw-away type ball end mill to enable smooth and highly accurate machining.

[Brief description of drawings]

FIG. 1 is a plan view of a throw-away type ball end mill provided with an embodiment of a clamp mechanism of the present invention.

FIG. 2 is a side view of a tip end portion of the throw-away type ball end mill shown in FIG.

3 is a front view of the tip end portion of the throw-away type ball end mill shown in FIG. 1. FIG.

FIG. 4 is a plan view of the throw-away tip 3 according to the embodiment of the present invention.

5 is a side view of the throw-away tip 3 shown in FIG.

FIG. 6 is a front view of the throw-away tip 3 shown in FIG.

FIG. 7 is a YY cross-sectional view in FIGS. 2 and 3.

FIG. 8 is a ZZ sectional view in FIGS. 1 and 3.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Tool main body 2 Tip mounting seat 3 Throw-away tip 4 Clamp screw (pressing means) 5 Cutting edge 6 Tip body 7 Rear end 12 of tip body 6 Mounting hole 13 Mounting hole 12 Concave V shape formed by rear end side of inner periphery Wall surface 14 Tip receiving portion 26 Circular body of clamp screw 4 (pressing portion) O Tool body 1 axis T Tool rotation direction X Center of mounting hole 12 (center of arcuate cutting edge 5) C Tip body 6 Gap between the rear end portion 7 and the bottom surface of the groove of the chip mounting seat 2 The angle between the concave V-shapes formed by the wall surfaces 13 and 13

Continued front page    (72) Inventor Masaya Tsuchiya             1511 Furumagi, Ishishita-cho, Yuki-gun, Ibaraki Prefecture             Mitsubishi Materials Corporation Tsukuba Works F-term (reference) 3C022 KK02 KK11 KK14 MM06                 3C046 EE01

Claims (6)

[Claims] 1. A cutting edge is formed on the tip side of a flat plate-shaped tip body, is inserted into a tip mounting seat formed on the tool body, and is pushed toward the rear end side by a pushing means provided on the tool body. By doing so, the rear end of the chip body is brought into contact with the receiving portion of the chip mounting seat, which is a throw-away chip removably mounted on the chip mounting seat, wherein the chip body has: A mounting hole that engages with the pressing means and receives a pressing force toward the rear end side is formed, and the mounting hole has a concave V-shape in which the rear end side portion of the inner periphery is recessed toward the rear end side. A throw-away tip that is characterized as being. 2. A rear end portion of the chip body is formed in a direction extending orthogonal to a bisector of a concave V-shape formed by a rear end side portion of an inner periphery of the mounting hole. The throw-away tip according to claim 1. 3. The cutting edge has a substantially arcuate shape, and the center of the arc is arranged on a concave V-shaped bisector formed by the rear end side portion of the inner periphery of the mounting hole. The throw-away tip according to claim 1 or 2, which is characterized. 4. The throw-away tip according to any one of claims 1 to 3 is inserted into a tip mounting seat formed on a tool body, and a rear end side is provided by a pressing means provided on the tool body. By pressing to bring the rear end of the chip body into contact with the receiving portion of the chip mounting seat,
A throwaway tip clamp mechanism detachably attached to the tip attachment seat, wherein the pressing means is inserted into and engaged with an attachment hole of the tip body, and a rear end portion of the inner periphery of the attachment hole is engaged. A throwaway tip clamping mechanism comprising: a pressing section having a circular cross section, which is in contact with a pair of concave V-shaped wall surfaces and presses the tip body toward the rear end side. 5. The receiving portion of the chip mounting seat has a gap between it and the rear end portion of the chip body at a portion on the bisector of a concave V-shape formed by the rear end side portion of the inner periphery of the mounting hole. The clamping mechanism for the throw-away tip according to claim 4, wherein the clamping mechanism is formed so as to be defined. 6. The tool body has a substantially columnar shape centered on the axis which is rotated about the axis, and the tip mounting seat is recessed along the axis at the tip of the tool body. The receiving portion of the chip mounting seat with which the rear end of the chip body abuts is formed on the groove bottom surface of the concave groove, and the pressing means inserts the mounting hole of the chip body into the mounting hole. The clamp mechanism for the throw-away tip according to claim 4 or 5, wherein the clamp mechanism is capable of being pressed toward the rear end side along the axis.