JP2011131337A - Clamp mechanism and cutting edge replaceable rotary tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve mounting strength to an insert mounting seat of a screw member with a screw hole, and to improve the positioning accuracy of the screw member with the screw hole at that time. <P>SOLUTION: This clamp mechanism includes: the insert mounting seat provided on a tool body; the screw member with the screw hole screwed with a female screw portion provided on the insert mounting seat and mounted to project out at least a part of a head portion from the insert mounting seat; a cutting insert locking a recessed locking portion provided on a peripheral edge of a lower opening of a through-hole to the head portion of the screw member with the screw hole; and an insert mounting screw inserted in the through-hole of the cutting insert, screwed with the screw hole of the screw member with the screw hole at the tip end, and locked to an upper opening of the through-hole of the cutting insert at the head portion. A concave curved surface portion is formed on the opening peripheral edge of the female screw portion of the insert mounting seat, and a convex curved surface portion corresponding to the concave curved surface portion is formed on a lower surface of the head portion of the screw member with the screw hole. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a clamp mechanism that detachably mounts a cutting insert with an insert mounting screw, and a blade-tip exchange type rotary tool such as a milling cutter provided with the clamp mechanism.

As a clamping mechanism for clamping a cutting insert, for example, Patent Document 1 proposes a structure having the following structure.
In this clamp mechanism, an insert mounting seat is provided in the tool body, and a screw member with a screw hole is screwed at the tip of the female thread portion of the insert mounting seat, and the head protrudes upward from the insert mounting seat. It is attached. A cutting insert is seated on the insert mounting seat with a recess engaging portion provided at a peripheral edge of a lower opening of a through hole formed in a central portion thereof being locked to a head portion of a screw member with a screw hole. Then, an insert mounting screw is inserted into the through hole of the cutting insert, and the tip thereof is screwed into the screw hole of the screw member with the screw hole. Thereby, the head of the insert mounting screw is engaged with the peripheral edge of the upper opening of the through hole of the cutting insert, and the cutting insert can be fixed to the tool body.

Japanese Patent Laid-Open No. 9-207090

By the way, in the clamp mechanism described above, the male screw portion at the tip of the screw member with the screw hole is screwed to the female screw portion formed on the insert mounting seat of the tool body, and the diameter of the screw member with the screw hole is increased. The screw member with a screw hole is fixed to the insert mounting seat by bringing the lower flat surface of the head into contact with the bottom flat surface of the concave step formed on the opening peripheral edge of the female screw portion of the insert mounting seat. .
However, the screw member with a screw used in this clamping mechanism is a very small member, and the head of the screw member with a screw hole and the contact portion of the insert mounting seat, specifically, the head of the screw member with a screw hole. The contact area between the lower flat surface and the bottom flat surface of the concave step formed on the opening peripheral edge of the female thread portion of the insert mounting seat cannot be increased. For this reason, in the above-mentioned clamp mechanism, the screw member with the screw hole cannot be screwed strongly into the female screw portion of the insert mounting seat, and the mounting strength of the screw member with the screw hole to the insert mounting seat is insufficient. There was a problem.
Further, in the above-described clamping mechanism, when the screw member with the screw hole is screwed and attached to the insert mounting seat, the play between the threads of the male screw portion of the screw member with screw hole and the female screw portion of the insert mounting seat is between. Therefore, there is a possibility that the screw member with the screw hole is fixed while being displaced from the normal position, and it is difficult to position and fix the screw member with the screw hole with respect to the insert mounting seat with high accuracy. there were.

  The present invention has been made under such a background, and can increase the mounting strength of the screw member with the screw hole to the insert mounting seat, and also improve the positioning accuracy of the screw member with the screw hole at that time. Therefore, an object of the present invention is to provide a clamp mechanism and a blade-tip-exchangeable rotary tool that can attach a cutting insert to a tool body with high strength and high accuracy.

  In order to solve the above-described problems and achieve such an object, the clamping mechanism of the present invention includes an insert mounting seat provided in a tool body, and a male screw portion at the tip of a female screw portion provided in the insert mounting seat. A screw member with a screw hole to which at least a part of the head protrudes from the insert mounting seat, and a through-hole formed at the center of the head of the screw member with screw hole. A cutting insert that is engaged with a concave engaging portion provided at a peripheral edge of the lower opening, and is inserted into the through hole of the cutting insert, and its tip is screwed into the screw hole of the screw member with the screw hole. A clamp mechanism including an insert mounting screw for locking a head portion to an upper opening of the through hole of the cutting insert, A concave curved surface portion is formed around the opening of the female screw portion, and a convex curved surface portion corresponding to the concave curved surface portion is formed on the lower surface of the head of the screw member with a screw hole. .

  In the clamp mechanism configured as described above, the convex curved surface portion formed on the lower surface of the head portion of the screw member with the screw hole when the male screw portion at the tip of the screw member with the screw hole is screwed into the female screw portion of the insert mounting seat. Is in contact with the concave curved surface portion formed on the periphery of the opening of the female thread portion of the insert mounting seat. As described above, since the lower surface of the head of the screw member with the screw hole and the opening peripheral edge of the female screw portion of the insert mounting seat are formed in curved surfaces corresponding to each other, the mere flat surfaces described in the background art contact each other. Compared with the case, the mutual contact area can be widened. For this reason, it becomes possible to screw a screw member with a screw hole strongly with respect to the internal thread part of an insert attachment seat, and can improve the attachment strength to the insert attachment seat of a screw member with a screw hole.

  Further, as described above, the lower surface of the head portion of the screw member with the screw hole and the opening peripheral edge of the female screw portion of the insert mounting seat are formed in curved surfaces corresponding to each other, so that the screw member with the screw hole is screwed. Accordingly, when they come into strong contact with each other, the position of the opening periphery of the female thread portion of the insert mounting seat with the head portion of the screw member with the threaded hole is naturally adjusted to be on the same axis. As a result, the positioning accuracy when the screw member with the screw hole is attached to the insert mounting seat is increased.

Further, a sheet having a through-locking hole is interposed between the insert mounting seat and the cutting insert, the screw member with a screw hole is inserted into the through-locking hole of the sheet, and the concave curve Instead of being formed on the opening periphery of the female thread portion of the insert mounting seat, the surface portion may be formed on the periphery of the upper opening of the penetration locking hole of the seat.
In this case, the portion on which the cutting insert is seated can be replaced with a sheet made of another material that is stronger in strength than the tool body, and thus the cutting insert can be attached to the tool body with stronger strength. .

  As described above, according to the present invention, the mounting strength of the screw member with a screw hole to the insert mounting seat can be increased, and the positioning accuracy of the screw member with the screw hole at that time can be increased. As a result, the cutting insert can be attached to the tool body with high strength and high accuracy.

It is the perspective view which looked at the blade-tip-exchange-type milling machine which is one Embodiment of the blade-tip-exchange-type rotary tool provided with the clamp mechanism of this invention from the front-end | tip outer periphery side. It is a disassembled perspective view of the principal part of the blade-tip-exchange-type milling machine shown in FIG. It is a side view which shows the screw member with a screw hole used with the blade-tip-exchange-type milling machine shown in FIG. It is sectional drawing of the principal part of the blade-tip-exchange-type milling machine shown in FIG. It is an expanded sectional view of the V circle part of FIG. It is a perspective view which shows a part of manufacturing process of the tool main body of the blade-tip-exchange-type milling machine shown in FIG. It is the perspective view which looked at the blade-tip-exchange-type milling which is other embodiment of the blade-tip-exchange-type rotary tool provided with the clamp mechanism of this invention from the front-end | tip outer periphery side. It is a disassembled perspective view of the principal part of the blade-tip-exchange-type milling machine shown in FIG. It is sectional drawing of the principal part of the blade-tip-exchange-type milling machine shown in FIG.

FIG. 1 thru | or 6 shows the blade-tip-exchange-type milling which is one Embodiment of the blade-tip-exchange-type rotary tool provided with the clamp mechanism of this invention. FIG. 1 is a perspective view of a blade-tip replaceable milling machine as viewed from the outer peripheral side of the tip, and FIG.
The cutting edge exchange type milling cutter 1 of this embodiment is a cutting edge exchange type milling cutter used when machining a relatively tough work material such as steel, and the cutting insert 7 is a work material machining with high toughness. It is a cutting insert for.

As shown in FIG. 1, the cutting edge replaceable milling machine 1 has a tool body 2 having a substantially disk shape centered on an axis O ₁ , and the tool body 2 has a base along the axis O ₁ in the radial center. An attachment portion 3 extending to the end side and having a tool attachment hole 3a is provided, and the blade tip replaceable milling cutter 1 is attached to a spindle of a machine tool (not shown) through the attachment portion 3. On the tip side of the tool body 2, a blade part 4 having a diameter larger than that of the attachment part 3 is provided, and when the blade tip replaceable milling cutter 1 is rotated in the tool rotation direction T around the axis O ₁ , The blade portion 4 is used for cutting a work material.

Further, at the end of the tool body 2 on the tip side along the direction of the axis O ₁ , a tip pocket 6 that is notched on the outer surface of the tool body 2 and opens toward the tip side and radially outward is spaced in the circumferential direction. A plurality of openings are formed. In the chip pocket 6, a base 8 having a shape corresponding to the outer shape of the cutting insert 7 is provided on the rear side in the tool rotation direction T. That is, here, since the cutting insert 7 is a plate-like body having a regular heptagon shape, the tip portion of the base 8 has a shape that forms a part of a regular hexagonal column.

As shown in FIG. 2, an insert mounting seat 10 for mounting the cutting insert 7 is provided on the front surface of the base 8 in the tool rotation direction T.
The insert mounting seat 10 is provided with a ring-shaped bottom surface 11 that forms a flat surface parallel to the axis O ₁ of the tool body 2, and is provided on the tool body mounting portion 3 side of the bottom surface 11 so as to stand up from the bottom surface. Wall surfaces 12A and 12B are provided with an angle and a predetermined interval. A female screw portion 13 is formed at the center of the bottom surface 11, and a screw member 15 with a screw hole is screwed into the female screw portion 13.

3 is a side view of the screw member 15 with a threaded hole, FIG. 4 is a cross-sectional view of the main part of the blade-tip-exchangeable milling cutter, and FIG. 5 is an enlarged cross-sectional view of the V-circle portion of FIG.
As shown in FIG. 3, the screw member 15 with the screw hole includes a male screw part 16 screwed to the female screw part 13 of the insert mounting seat 10 and a head set larger than the outer diameter of the male screw part 16. 17. A screw hole 18 is formed at the center of the head 17, and the screw hole 18 is formed so as to reach the center of the male screw part 16 in the length direction. As shown in FIG. 4, a hexagonal hole 19 for clamping that is used when the screw member 15 with a screw hole is screwed to the female screw portion 13 is formed further on the tip side of the screw hole 18. The hexagonal hole 19 for clamping does not necessarily have this shape, and may be a + shape or a − shape.

The head 17 of the screw member 15 with the screw hole has an upper and lower two-stage structure composed of a lower diameter enlarged portion 17A and an upper small diameter portion 17B. On the lower surface of the enlarged diameter portion 17A, a convex curved surface portion 17AA is formed so as to gradually decrease in diameter as it goes downward from the upper end. The small-diameter portion 17B is formed to have a diameter substantially the same as the outer diameter of the lower male screw portion 16. The screw member 15 with the screw hole is fixed at a proper position with respect to the insert mounting seat 10 by the male screw portion 16 being screwed into the female screw portion 13. At this time, the height of the small diameter portion 17B is set so that the upper portion of the small diameter portion 17B protrudes upward from the bottom surface 11 of the insert mounting seat 10.
On the other hand, a concave curved surface portion 13AA corresponding to the convex curved surface portion 17AA is formed at the opening peripheral edge of the female screw portion 13 of the insert mounting seat 10.

  That is, as shown in FIG. 5, the screw member 15 with the screw hole has screw threads 15 corresponding to each other when the male screw portion 16 is screwed into the female screw portion 13 and is fixed to the insert mounting seat 10 at a proper position. The convex curved surface portion 17AA of the holed screw member 15 and the concave curved surface portion 13AA of the insert mounting seat 10 are contacted with a ring-shaped curved band D instead of a point or a line.

  In addition, it is preferable that the curvature radii of the convex curved surface portion 17AA of the screw member 15 with the screw hole and the concave curved surface portion 13AA of the insert mounting seat 10 are the same, but it is not always necessary to be the same. Even if the radius of curvature is set to be slightly larger than the other side, when they come into contact with a predetermined pressing force, at least one of them is elastically deformed so that it comes into contact with the ring-shaped curved zone D. If there is enough.

The cutting insert 7 is attached by an insert attachment screw 20 on the upper side of the insert attachment seat 10 to which the screw member 15 with the screw hole is attached.
As shown in FIG. 2, the cutting insert 7 is formed in a regular heptagonal flat plate shape by a hard material such as cemented carbide, and includes an insert body 21 having a through hole 21a at the center thereof. The insert body 21 includes a pair of front and back rake faces 22 each having a regular heptagonal shape when viewed from the front, and a plurality of rake faces 22 that are arranged around the rake faces 22 on the front and back sides and that intersect with the rake faces 22. And a plurality of cutting blades 24 which are formed on the ridge line of the rake face 22 and the outer peripheral face 23 and which make a pair on the front and back. The rake face 22 includes a seating surface 25 provided on the outer periphery of the through hole 21a, and a breaker portion 26 that inclines so as to gradually protrude outward in the thickness direction from the seating surface 25 toward the outer periphery.
Here, the cutting blades 24 arranged on each side of the rake face 22 are rotationally symmetric with respect to each other about the center axis of the rake face 22.

That is, the cutting insert 7 of this embodiment has a cutting edge 24 formed on the intersecting ridge line of the rake face 22 and the outer peripheral face 23 so as to protrude outward in the thickness direction from the seating face 25. A breaker portion 26 that is inclined with a predetermined inclination angle is formed between the blade 24 and the seating surface 25 so as to be relatively wide. For this reason, the chip can be easily cut by the breaker portion 26, and as described above, the cutting insert can be processed even with a work material rich in toughness.
In addition, when the cutting insert 7 is attached to the insert mounting seat 10, two of the seven outer peripheral surfaces 23 of the insert body are brought into contact with the wall surfaces 12A and 12B of the insert mounting seat 10, respectively.

As shown in FIGS. 4 and 5, a concave locking portion 27 is formed at the periphery of the lower opening of the through hole 21 a of the insert body 21, and the concave locking portion 27 has a head of the screw member 15 with the screw hole. The small-diameter portion 17B is inserted. Here, the center axis O ₂ of the screw hole with the screw member 15, the wall surface 12A of the insert attaching seat 10 with respect to the central axis O ₃ of the cutting insert 7 which coincides with the central axis of the through hole 21a, toward the corner of the 12B Is eccentric by a predetermined amount d. Therefore, the diameter of the open end of the concave locking portion 27 is substantially set to a value obtained by adding twice the predetermined amount d which is an eccentricity to the outer diameter of the small diameter portion 17B of the head portion of the screw member 15 with the screw hole. Yes.
That is, here, the head small-diameter portion 17 </ b> B of the screw member 15 with the screw hole is locked only to a part of the inner peripheral surface of the concave locking portion 27 of the insert body 21.

As shown in FIG. 2, the insert mounting screw 20 is composed of a lower male screw portion 20a and an upper head portion 20b, and a lower surface of the head portion 20b gradually increases in a tapered shape as it goes upward. It has become. The insert mounting screw 20 has a male screw portion 20a inserted into the through hole 21a of the cutting insert 7 and the tip thereof is screwed into the screw hole 18 of the screw member 15 with screw hole. At this time, the head locking portion 20bb of the insert mounting screw 20 is locked to the ring-shaped locking portion 21bb formed at the periphery of the upper opening of the through hole 21a of the cutting insert 7, thereby cutting the cutting insert. 7 is attached to the insert mounting seat 10. Moreover, the cutting insert 7 is removed from the insert attachment part 20 by removing the attachment screw 22.
That is, the clamp mechanism C of this embodiment includes the insert mounting seat 10, the screw member 15 with the screw hole, the cutting insert 7, and the insert mounting screw 20.

In addition, as a method of processing the concave curved surface portion 13AA on the opening peripheral edge of the female screw portion 13 of the insert mounting seat 10, an end mill E whose tip is formed in an arc shape is used as shown in FIG. There is a method in which the end mill E or the tool body 2 is rotated around the central axis O ₂ while being inserted obliquely with respect to the central axis O ₂ . When there are a large number of insert mounting seats 10 as in this embodiment, the end mill E is kept parallel to the central axis O ₂ of the female thread portion 13 due to the narrow interval between adjacent bases 8. In some cases, the concave curved surface portion 13AA cannot be processed. In this case, the processing method is effective.

  As described above, according to the cutting edge exchange type rotary tool according to this embodiment, the cutting insert 7 can be attached to the tool body 2 as follows.

First, the tip of the male screw part 16 of the screw member 15 with screw hole is screwed with the female screw part 13 of the insert mounting seat 10, and a hexagon wrench (not shown) is fitted into the hexagon hole 19 and rotated to thereby rotate the screw with screw hole. The male screw portion 16 of the member 15 is screwed into the female screw portion 13.
At this time, first, the convex curved surface portion 17AA on the lower surface of the head diameter-expanded portion 17 of the screw member 15 with the screw hole is disposed at a certain distance from the concave curved surface portion 13AA of the insert mounting seat 10 or is convex. Only a part of the curved surface portion 17AA in the circumferential direction is in contact with the concave curved surface portion 13AA.
Thereafter, as the male screw portion 16 of the screw member 15 with the screw hole is screwed into the female screw portion 13, the distance between the convex curved surface portion 17AA and the concave curved surface portion 13AA is narrowed, and the entire circumferential direction of the convex curved surface portion 17AA is a concave curved surface portion. 13AA will be contacted. At this time, the position of the head 17 of the screw member 15 with the screw hole is adjusted with respect to the opening peripheral edge of the female thread portion 13 of the insert mounting seat 10 so as to be naturally the same axis. As a result, the positioning accuracy when the screw member 15 with the screw hole is attached to the insert attachment seat 10 can be improved.

  Further, as described above, since the lower surface of the head portion 17 of the screw member 15 with the screw hole and the opening peripheral edge of the female screw portion 13 of the insert mounting seat 10 are formed in curved surfaces corresponding to each other, mere flat surfaces are formed. Compared with the case of contact, the mutual contact area can be increased. Therefore, the screw member 15 with the screw hole can be strongly screwed into the female screw portion 13 of the insert mounting seat 10, and thereby the mounting strength of the screw member 15 with the screw hole to the insert mounting seat 10 can be increased. Can be increased.

  As for the screw member 15 with the screw hole mounted as described above, the small diameter portion 17B of the head projects upward from the bottom surface 11 of the insert mounting seat 10. The concave locking portion 27 is fitted to the protruding small-diameter portion 17B of the head, and the seating surface 25 is brought into contact with the bottom surface of the insert mounting seat 10, and two of the seven outer peripheral surfaces 23 are arranged. The cutting insert 7 is attached to the insert mounting seat 10 so as to contact the wall surfaces 12A and 12B.

In this state, the male screw portion 20a at the tip of the insert mounting screw 20 is inserted into the through hole 21a of the cutting insert 7, and the tip is screwed into the screw hole 18 of the screw member 15 with the screw hole. Then, the insert mounting screw 20 is fixed to the screw member 15 with the screw hole by fitting and rotating a wrench (not shown) in the engagement hole 20bb on the upper surface of the head of the insert mounting screw 20. At this time, the locking portion 20bb of the insert mounting screw 20 comes into contact with the ring-shaped locking portion 21bb of the cutting insert 7 and strongly presses the cutting insert 7 downward.
According to the clamp mechanism C, the small diameter portion 17B of the head of the screw member 15 with the screw hole is protruded upward from the bottom surface 11 of the insert mounting seat 10, and the concave shape of the cutting insert 7 is projected on the small diameter portion 17B of the protruding head. Since the engaging portion 27 is fitted, even if the cutting insert 7 is damaged, it is possible to prevent the cutting insert 7 from being scattered outward due to the centrifugal force.

FIG. 7 is a perspective view of a blade-tip replaceable milling tool, which is another embodiment of the blade-tip replaceable rotary tool provided with the clamp mechanism of the present invention, as viewed from the outer periphery of the tip. FIG. FIG. 9 is a cross-sectional view of the main part of the blade tip replaceable milling cutter shown in FIG.
For convenience of explanation, the same components as those described in the embodiment are given the same reference numerals, and the description thereof is omitted.

  The blade tip replaceable milling cutter 30 of this embodiment is different from that of the above-described embodiment in that a sheet 42 having a through locking hole 41 is interposed between the insert mounting seat 40 and the cutting insert 7, and Instead of the concave curved surface portion 50 corresponding to the convex curved surface portion 17AA of the screw member 15 with the screw hole being formed at the opening peripheral edge of the female screw portion 13 of the insert mounting seat 30, the upper opening of the penetration locking hole 41 of the seat 41 is formed. It is the point formed in the periphery. Note that the bottom surface of the insert mounting seat 40 having a substantially regular heptagon shape is formed flat.

That is, in this embodiment, the seat 42 is interposed between the insert mounting seat 40 and the cutting insert 7, so that the portion on which the cutting insert 7 is seated is another material stronger than the tool body 2. In this respect, the cutting insert 7 can be attached to the tool body 2 with higher strength.
In this embodiment also, the insert mounting seat 30 of the screw member 15 with the screw hole is provided by providing the concave curved surface portion 50 corresponding to the convex curved surface portion 17AA on the periphery of the upper opening of the through-hole 41 of the seat 41. Similar to the above-described embodiment, it is possible to increase the mounting strength of the screw member and to increase the positioning accuracy of the screw member 15 with the screw hole at that time.

In addition, this invention is not limited to the above-mentioned embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, in the above-described embodiment, a regular heptagonal flat plate is used as the cutting insert 7, but is not limited to this, and a simple heptagonal flat plate cutting insert or other regular polygon or simple polygon is used. The present invention is also applicable to those using a flat cutting insert.

  Moreover, although the said embodiment demonstrated the example which applied the clamp mechanism C of this invention to the blade-tip-exchange-type milling machine, this invention is not limited to this, This invention is applied also to other blade-tip-exchange-type rotary tools, such as an end mill. Applicable.

DESCRIPTION OF SYMBOLS 1 Cutting-edge-exchange-type mill 2 Tool main body 4 Blade part 6 Tip pocket 7 Cutting insert 8 Base 10 Insert mounting seat 11 Bottom surface 12A, 12B Wall surface 13 Female thread part 13AA Concave curved surface part 15 Screw member with screw hole 16 Male thread part 17 Head 17AA Convex curved surface portion 18 Screw hole 20 Insert mounting screw 20a Male screw portion 21 Insert body 21a Through hole 21bb Ring-shaped locking portion 24 Cutting blade 25 Seating surface 27 Concave locking portion T Tool rotation direction (rotation direction)
C Clamp mechanism

Claims (3)

An insert mounting seat provided on the tool body;
A screw member with a screw hole to which a male screw portion at a tip is screwed to a female screw portion provided in the insert mounting seat, and at least a part of a head portion is mounted to protrude from the insert mounting seat;
A cutting insert for locking a concave locking portion provided at a peripheral edge of a lower opening of a through hole formed in a central portion on the head of the screw member with the screw hole,
Insert mounting that is inserted into the through hole of the cutting insert, the tip of which is screwed into the screw hole of the screw member with the screw hole, and the head is locked to the upper opening of the through hole of the cutting insert A clamping mechanism comprising a screw,
A concave curved surface portion is formed at the periphery of the opening of the female screw portion of the insert mounting seat,
A clamping mechanism, wherein a convex curved surface portion corresponding to the concave curved surface portion is formed on a lower surface of the head portion of the screw member with a screw hole. Between the insert mounting seat and the cutting insert, a sheet having a through-hole is provided,
The screw member with a screw hole is inserted through the through-holding hole of the sheet,
2. The concave curved surface portion is formed at a peripheral edge of an upper opening of the through-locking hole of the seat, instead of being formed at an opening peripheral edge of the female screw portion of the insert mounting seat. The clamp mechanism described in 1.   A cutting edge replaceable rotary tool comprising the clamp mechanism according to claim 1.

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