JP2002046012A - Throwaway type end mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attach a throwaway tip stably. SOLUTION: Recessed sections 17a and 17a which are adjacent to the end mill body base end side of a tip rear end face 12d are provided on both outer periphery sides of the tip receiving face 13a of an end mill body 11, and wedges 18 and 18 are inserted into the recessed section 17a and 17a. The wedges 18 and 18 are clamped by a clamp screw 19 having male thread sections 19a and 19a threadedly engaged with the female thread sections 18c and 18c provided on the wedges 18 and 18. The inclination angle θ between a tip pressing face 18a and the insertion direction of the wedges 18 is set to a value satisfying an inequality 5 deg.<=θ<=30 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away type end mill in which a tip having, for example, an arc-shaped cutting edge is detachably attached to the end of an end mill body.

[0002]

2. Description of the Related Art Conventionally, as a throw-away type end mill of this type, a throw-away type ball end mill as shown in FIGS. 7 (a) and 7 (b) has been known.
A groove 3 for mounting a plate-like chip 2 having an arc-shaped cutting blade and a chip hole 2a through which a clamp bolt 7 penetrates is formed in the tip 1a of the end mill 1 from the center of the tip 1a toward the base end of the end mill body. A clamp hole 6 is formed in the chip sandwiching portions 5a and 5b on both sides of the groove 3 in a direction perpendicular to the groove 3. Then, by clamping the clamp bolt 7 screwed into the clamp hole 6, the chip holding portion 5a is inserted through the screw head receiving portion 6a.
Is pressed, whereby the chip 2 is held between the chip holding portions 5a and 5b. Here, the chip rear end surface 2c and the chip receiving surface 4 at the bottom portion of the groove 3 are formed in a flat shape in a side view.
Is attached to the chip receiving surface 4 to mount the chip 2.

[0003]

However, in the throw-away type end mill having the above-described structure, depending on the hole position accuracy of the throw-away tip 2, the tip rear end face 2c and the tip receiving face 4 do not adhere to each other and a gap is formed. Or the tip 2 is loosened during cutting, and the cutting edge position accuracy is impaired, and accordingly, the cutting accuracy may be impaired. As a result, there is a problem that the tip 2 rotates around the tip hole 2a and shifts, and the mounting rigidity of the tip 2 decreases. In addition, for example, Japanese Patent Application Laid-Open No. 8-252714 also discloses an end mill having a chip receiving surface having a concave V-shape in plan view and a tip rear end face having a convex V-shape in plan view. However, even in such a case, it is inevitable that the chip is rattled depending on the molding accuracy of the V-shape.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a throw-away type end mill capable of stably fastening a throw-away tip and having high rigidity for mounting the tip.

[0005]

Means for Solving the Problems To solve the above problems,
In order to achieve such an object, the present invention provides a tip mounting groove at the end of the end mill main body, and a clamp bolt hole orthogonal to the groove, and a chip is inserted into the groove. In a throw-away type end mill in which a clamp bolt is screwed so as to penetrate the tip hole into the clamp bolt hole and the tip is held at the tip of the end mill body, on the outer peripheral surface of the end mill body,
It is characterized in that a concave portion adjacent to the base end side of the end mill body on the chip rear end surface is provided, and the chip rear end surface is pressed by inserting a wedge into the concave portion. According to such a throw-away type end mill, in addition to the chip holding portions formed on both sides of the groove by tightening the clamp bolt to hold down the chip, the wedge presses the chip rear end face toward the end mill body front end side. , The tip rear end face and the tip pressing surface of the wedge are in close contact,
Since the rear end portion of the hole of the chip is in close contact with the shaft portion of the clamp bolt, the chip can be stably fastened and the mounting rigidity of the chip can be increased.

Further, the present invention is characterized in that the concave portions are provided at two positions adjacent to the ends of the rear end surfaces of the chips on the base end side of both end mill bodies. According to the present invention as described above, the tip can be more stably fastened as compared to the case where the wedge is inserted into one recess.

[0007] Further, the present invention is characterized in that the wedge is tightened by a clamp screw having a male screw portion screwed into a female screw portion provided in the wedge. According to the present invention, as compared with the case where the wedge is simply inserted into the concave portion, the force of the wedge chip pressing surface pressing the chip rear end surface can be increased, and the chip can be more stably fastened.

The present invention also provides that the tip pressing surface for pressing the tip rear end face of the wedge has an inclination angle θ with respect to the insertion direction of the wedge in a range of 5 ° ≦ θ ≦ 30 °. Features. When the inclination angle θ is less than 5 °, the force of the chip pressing surface pressing the rear end face of the chip becomes weak, so that the distance for inserting the wedge into the concave portion must be long, and the size of the concave portion is large. Unnecessary space increases. When the inclination angle θ is larger than 30 °,
The size of the wedge is increased, and the size of the chip is reduced accordingly, and the rigidity of the chip is reduced.
Alternatively, in order to maintain rigidity, the size of the chip itself must be increased, and the useless space increases.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a plan view of a tip end of a throw-away type ball end mill showing one embodiment of the present invention, FIG. 2 is a side sectional view of the tip end, and FIG. 3 is a plan view showing a state where a chip is not mounted on the end mill. FIG. 4 is a cross-sectional view, FIG. 4 is a side cross-sectional view showing a state where a chip is not mounted on the end mill, FIG. 5 is a plan view of a chip mounted on the end mill, and FIG. 6 is a state where a chip is mounted on the end mill. It is a plane sectional view showing.

[0010] An end mill 11 according to an embodiment of the present invention.
Has a substantially cylindrical shape, and has a groove 13 for mounting the tip 12 from the center of the end portion 11a of the end mill body 11 toward the base end side of the end mill body 11 as shown in FIGS. Is provided. This groove 13 allows the first chip holding portion 14 to hold the chip 12 from both sides.
a, a second chip holding portion 14b is formed, and a clamp bolt hole 15 orthogonal to the first chip holding surface 14c and the second chip holding surface 14d is formed in the first chip holding portion 14a and the second chip holding portion 14b. It is formed. The clamp bolt hole 15 has an opening on the outer peripheral surface on the first chip holding portion 14a side for receiving the head 16a of the clamp bolt 16, and an opening on the outer peripheral surface on the second chip holding portion 14b side. And a hole 15c having an inner diameter larger than the inner diameter of the female screw portion 15b, opening on the groove 13 side of the receiving portion 15a and the female screw portion 15b, and into which the shaft portion 16b of the clamp bolt 16 is fitted. Is formed. The clamp bolt 16 is, as shown in FIG.
The clamp bolt hole 1 is connected to the lower end of the head 16a.
5 and a male screw 16c formed to have a smaller diameter than the shaft 16b and screwed into the female screw 15b of the clamp bolt hole 15. Hole 12 of chip 12 inserted in
c is screwed into the clamp bolt hole 15 so as to pass through.

Further, a clamp screw hole 17 is formed in a direction along the chip receiving surface 13a, adjacent to the base end side of the end mill main body of the chip receiving surface 13a disposed on the bottom surface of the groove 13. As shown in FIGS. 3 and 4, the clamp screw hole 17 is provided in the end mill main body 11 on the chip receiving surface 13a.
Recesses 17a, 17a formed in substantially cylindrical spaces for opening the wedges on the outer peripheral sides of the chip receiving surface 13a and adjoining the end mill body base end side.
And a hole 17b formed between the recesses 17a, 17a and having a smaller diameter than the recesses 17a, 17a and formed in a columnar space. Also, the recess 17
a, 17a are connected to the bottom surface of the groove 13, and the front end side of the end mill body of the recesses 17 a, 17 a is the groove 1.
It is in a state where it is connected to 3. Further, a slit 20 is provided at the center of the groove width of the chip receiving surface 13a of the groove 13 toward the base end side of the end mill main body, and the chip receiving surface 13a and the hole 17b of the clamp screw hole 17 are connected.

As shown in FIGS. 1 and 2, the wedge 18 inserted into the concave portion 17a of the clamp screw hole 17 has a substantially cylindrical shape, has a center line O eccentric from the center thereof, and has a male screw portion of the clamp screw 19. Female thread portion 18 into which 19a is screwed
c is formed. In addition, the outer peripheral surface is an arc portion 18.
b and a chip pressing surface 18a composed of a flat surface,
A chip pressing surface 18a formed of a flat surface is formed on the side opposite to the direction in which the center line O of the female screw portion 18c is eccentric. Further, the tip pressing surface 18a is connected to the end mill main body 11.
The inner thread portion 1c is inclined so as to approach the center line O of the female thread portion 18c toward the inner side.
The angle of inclination formed by the direction of the center line O of 8c, that is, the direction in which the wedge 18 is inserted is θ. Here, the inclination angle θ is set in a range of 5 ° ≦ θ ≦ 30 °.

The clamp screw 19 is, as shown in FIG.
Male thread 1 screwed into female thread 18c of wedge 18
9a, 19a, and a shaft portion 19b connected to the lower ends of the male screw portions 19a, 19a and having a smaller diameter than the male screw portions 19a, 19a.
The a and 19a are provided with screw grooves of opposite directions to form a double screw. The wedges 18 and 18 inserted in the recesses 17a and 17a of the clamp screw hole 17 are simultaneously tightened to the inside of the end mill body 11. .

As shown in FIG. 5, the tip 12 is formed in a substantially disk shape from a hard material such as a cemented carbide, and has a hole 12 through which the clamp bolt 16 is inserted at a substantially central portion thereof.
c is formed, and the rake face 1 of the chip 12 is formed.
An arc-shaped cutting blade 12b coaxial with the hole 12c is formed at the side ridge of 2a. The tip rear end face 12d has a flat shape in a side view, and includes a parallel portion 12e and an inclined portion 12f in a plan view.
It is located at both ends of 2e, and is inclined so as to be inclined toward the tip end of the chip 12 as it moves away from the parallel portion 12e. At this time, the inclination of the inclined portion 12f corresponds to the tip pressing surface 18a of the wedge 18,
The inclination angle with respect to e is θ. The thickness of the chip 12 is slightly smaller than the groove width of the groove 13 in the penetrating direction of the clamp bolt 16, and the chip holding surfaces 15 c and 15 d are formed.
The size is such that it can be inserted between them.

In the indexable end mill having the above-described structure, the tip 12 is mounted as follows. First, insert the chip 12 into the groove 13 and insert the chip rear end face 12d.
Until it contacts the chip receiving surface 13a. Next, the clamp bolt 16 is inserted into the clamp bolt hole 15 so as to penetrate the hole 12c of the chip 12, and screwed.

Then, the screwed clamp bolt 16
Receiving part 1 of the clamp bolt hole 15 by the head 16a of
5a is pressed, whereby the first chip holding portion 14a of the end mill main body 11 is elastically deformed so as to approach the second chip holding portion 14b. Here chip receiving surface 1
Since the slit 20 having a predetermined length is provided from the center of the groove width of 3a toward the base end side of the end mill body, elastic deformation such that the first chip holding portion 14a approaches the second chip holding portion 14b side. Is easy to proceed smoothly. At this time, as shown in FIG.
By the tightening of No. 6, the force A for pressing the tip side from the hole 12c of the chip 12 from both the first chip holding portion 14a and the second chip holding portion 14b and the force B for pressing the rear end side from the hole 12d of the chip 12 receive. However, at this stage, a gap is formed between the tip rear end surface 12d and the tip receiving surface 13a or between the rear end portion of the hole 12c of the tip 12 and the shaft portion 16b of the clamp bolt 16. .

Next, the wedges 18, 18 are moved toward the inside of the end mill body 11 by tightening the clamp screw 19, which is a double screw. As a result, as shown in FIG. 6, the inclined portion 12f of the tip rear end surface 12d receives a force C pressed from the chip pressing surface 18a of the wedge 18, and the inclined portion 12f and the chip pressing surface 18d
a adheres. In addition, a component force of the force C received by the inclined portion 12f of the tip rear end face 12d acts toward the front end side of the end mill main body, so that the rear end portion of the hole 12c of the tip 12 is pressed against the shaft portion 16b of the clamp bolt 16. D
Then, the rear end portion of the hole 12c and the clamp bolt 16
Is tightly attached, and the chip 12 is stably fixed.

In the throw-away type ball end mill configured as described above, when the tip 12 is mounted,
In addition to pressing down the chip 12 by the first chip holding portion 14a and the second chip holding portion 14b, by tightening the clamp screw 19, the chip pressing surface 18a of the wedge 18 makes the inclined portion 12f of the chip rear end surface 12d the end of the end mill main body. Side, the inclined portion 12f and the chip pressing surface 18a are in close contact with each other.
Since the rear end side portion c is brought into close contact with the shaft portion 16b of the clamp bolt 16, the tip 12 can be stably fastened,
The mounting rigidity of the insert 12 is increased, and stable cutting edge position accuracy can be obtained.

The inclination angle θ formed by the tip pressing surface 18a of the wedge 18 and the insertion direction of the wedge 18 is 5 ° ≦ α ≦ 30.
Since it is set in the range of ゜, the chip 12
Can be stably fastened. That is, when the inclination angle θ is less than 5 °, the force C by which the chip pressing surface 18a presses the inclined portion 12f of the chip rear end surface 12d becomes weak, so that the distance for inserting the wedge 18 into the recess 17a must be long. In addition, the useless space increases due to the size of the concave portion 17a. When the inclination angle θ is 30
If it is larger than ゜, the size of the wedge 18 increases, and the size of the chip 12 decreases accordingly, and the rigidity of the chip 12 decreases. Alternatively, in order to maintain rigidity, the size of the chip 12 itself must be increased, and a useless space increases.

In the present embodiment, a double screw clamp screw is used. However, the present invention is not limited to this. A normal clamp screw may be used, and the means for tightening the wedge is not limited to the clamp screw. . Although the ball end mill has been described in the present embodiment, the present invention can be applied to an end mill to which a square type chip having a straight cutting edge is mounted.

[0021]

As described above, according to the present invention,
A concave portion is provided adjacent to the base end side of the end mill main body on the chip rear end surface, and the chip rear end surface is pressed by inserting a wedge into the concave portion, so that when the chip is mounted, the chip is held down by the chip holding portion. In addition, by tightening the wedge, the wedge presses the rear end face of the chip against the front end side of the end mill body, so that the tip pressing surface of the wedge and the rear end face of the chip are in close contact with each other. Since the tip is brought into close contact with the portion, the tip can be stably fastened, and the rigidity of the tip mounting can be increased. Therefore, rattling of the tip can be prevented and stable blade tip position accuracy can be obtained. Further, the recess may be provided at two places adjacent to both ends of the rear end face of the chip, so that the chip can be more stably fastened as compared with the case where the wedge is inserted in one place. Further, the wedge may be configured to be tightened by a clamp screw having a male screw portion to be screwed into a female screw portion provided on the wedge, and may be more stably than simply inserting the wedge into the concave portion. Wedges can be attached. Further, the inclination angle θ formed by the tip pressing surface of the wedge and the insertion direction of the wedge is 5 ° ≦ α ≦
Since the angle is set in the range of 30 °, the tip pressing surface of the wedge can obtain a stable force for pressing the rear end face of the tip, and the tip can be stably fastened.

[Brief description of the drawings]

FIG. 1 is a plan view of a tip portion of a throw-away type ball end mill showing one embodiment of the present invention.

FIG. 2 is a side cross-sectional view of a tip portion of a throw-away type end mill showing one embodiment of the present invention.

FIG. 3 is a plan cross-sectional view of a tip end showing a state in which a tip is not mounted on a throw-away type end mill showing one embodiment of the present invention.

FIG. 4 is a side cross-sectional view of a tip end showing a state in which a tip is not mounted on a throw-away type end mill showing one embodiment of the present invention.

FIG. 5 is a plan view of a tip mounted on a throw-away type end mill showing one embodiment of the present invention.

FIG. 6 is a plan sectional view showing a state in which a tip is mounted on a throw-away type end mill showing one embodiment of the present invention.

FIG. 7 (a) is a side sectional view of a tip portion showing a conventional throw-away type end mill, and FIG. 7 (b) is a plan view of the tip portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 End mill 12 Tip 12c hole 12d Tip rear end face 12e Flat portion 12f Inclined portion 13 Groove 13a Chip receiving surface 14a First chip holding portion 14b Second chip holding portion 15 Clamp bolt hole 16 Clamp bolt 17 Clamp screw hole 17a Concave portion 18 Wedge 18a Tip pressing surface 18c Female thread 19 Clamp screw 19a Male thread θ Tilt angle

Claims (4)

[Claims] 1. A tip mounting groove and a clamp bolt hole orthogonal to the groove are provided at a tip end of an end mill body. A chip is inserted into the groove, and a chip hole is inserted into the clamp bolt hole. In a throw-away type end mill in which a clamp bolt is screwed so as to penetrate and a tip is held at a distal end portion of an end mill main body, a concave portion adjacent to a base end side of the end mill main body at a tip rear end surface is provided in a bottom surface portion of the groove. A throw-away end mill, wherein a rear end face of the chip is pressed by inserting a wedge into the recess. 2. The throw-away type end mill according to claim 1, wherein the concave portion is provided at two locations adjacent to the base end side of the end mill main body at both ends of a tip rear end surface. . 3. The indexable end mill according to claim 1, wherein the wedge is tightened by a clamp screw having a male screw portion screwed into a female screw portion provided on the wedge. Indexable end mill. 4. The indexable end mill according to claim 1, wherein an inclination angle θ between a tip pressing surface for pressing a tip rear end face of the wedge and an insertion direction of the wedge is 5; A throw-away type end mill characterized by being set in the range of ゜ ≦ θ ≦ 30 ゜.