JPH042745Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an end mill in which a plurality of peripheral cutting edges and a plurality of bottom cutting edges are formed in the end mill body.

[Prior Art] Conventionally, when cutting grooves or stepped portions in a workpiece, an end mill having a main body integrally formed with a bottom blade and a peripheral blade has been used.

This end mill has a cylindrical end mill body made of high-speed steel, etc., and a plurality of bottom blades extending in the radial direction are formed on the tip surface of the end mill body at positions that equally divide the tip surface. , a plurality of outer circumferential cutters are formed, each of which has its tip connected to the outer circumferential end of the bottom cutter and whose axial direction extends toward the proximal end, and the radial rake angles of these outer circumferential cutters are equal angles to each other. It is said that

In the conventional end mill configured as described above, the end mill main body is rotated and the peripheral cutter and bottom cutter cut the side and bottom surfaces of the workpiece, respectively, thereby machining grooves, steps, etc.

[Problems to be solved by the invention] However, in the above conventional end mill,
Since the outer circumferential cutters have the same radial rake angle, the magnitude of the cutting force acting on the end mill body by these outer circumferential cutters is equal to each other. Therefore, cutting forces of equal magnitude from these peripheral blades regularly act on the end mill body.

For this reason, in the conventional end mill mentioned above,
Due to certain cutting conditions such as rotation speed, the end mill body resonates with the constant periodic vibration caused by the cutting force of the peripheral blade, generating small amplitude vibrations and chatter.
As a result, there was a problem in that not only the outer peripheral cutting edge and the bottom cutting edge were damaged, but also the finished surface roughness deteriorated.

[Purpose of the invention] This invention was made in view of the above circumstances.
The object of the present invention is to provide an end mill that can prevent small vibrations caused by cutting force from occurring in the end mill body.

[Means for Solving the Problems] The end mill of this invention has a radial rake angle of at least one of the plurality of peripheral blades formed on the outer periphery of the tip of the end mill body, by adjusting the radial rake angle of at least one of the peripheral blades of the other peripheral blades. This is set at a different angle from the radial rake angle.

[Function] In the end mill of this invention having the above-mentioned configuration, the magnitude of the cutting force acting on the end mill body differs depending on the peripheral cutters having different radial rake angles. Therefore, cutting forces of different magnitudes are sequentially applied to the end mill body. As a result, regular vibrations that would cause the end mill body to resonate are not generated in the end mill body, so vibrations and chatter caused by the cutting force are prevented from occurring.

[Embodiment] FIGS. 1 and 2 show a first embodiment of the end mill of this invention, and reference numeral 1 in the figures indicates the end mill body of this end mill.

The end mill main body 1 is made of high-speed steel, cemented carbide, etc. and has a substantially cylindrical appearance, and has four bottom blades 2 extending in the radial direction on its tip surface and spaced at equal intervals in the circumferential direction. It is formed. Further, on the outer periphery of the end mill main body 1, the tip portion is attached to the bottom blade 2...
Four outer circumferential blades 3, 4, 5, and 6 are formed at equal intervals in the circumferential direction, continuing from the outer circumferential end of the blade and spiraling toward the base end.

As shown in FIG. 1, these peripheral blades 3
6, the radial rake angles of the peripheral cutters 3 and 5, which are axially symmetrical, are each _α1 . On the other hand, the radial rake angles of the outer peripheral cutters 4 and 6 located between the outer peripheral cutters 3 and 5 are each set to α ₂ .
Here, the magnitudes of these radial rake angles α ₁ and α ₂ are set to be α ₁ >α ₂ .

In the end mill having the above configuration, the radial rake angles α 1 and α 2 of the peripheral blades 3, 5 and 4, 6, etc. are set to different angles, so that the radial rake angles α ₁ and α ₂ of the peripheral blades 3, 5 and 4, 6, etc. The cutting force is different between the outer peripheral blades 3 and 5 and the outer peripheral blades 4 and 6.

As a result, in this end mill, cutting forces of different magnitudes are applied to the end mill body 1 alternately, so that regular vibrations that cause the end mill body 1 to resonate are not generated. Therefore,
Since vibration and chatter caused by the cutting force described above do not occur, the cutting edge does not break at any rotation speed, and excellent finished surface roughness can be obtained [Other Examples ] Figures 3 to 5 show a second embodiment of this invention, and the same components as those shown in Figures 1 and 2 are given the same reference numerals and their explanations are omitted. .

3 to 5, in this end mill, four cutting edges 11, 12, 13, and 14 formed on the outer peripheral surface of the end mill body 1 have different helix angles θ ₁ , θ ₂ , θ ₃ and θ ₄ . The radial rake angles of the axially symmetrical peripheral blades 11 and 13 of these peripheral blades 11 to 14 are each a positive angle α ₃ . On the other hand, the radial rake angles of the peripheral blades 12 and 14 located between the peripheral blades 11 and 13 are each a negative angle -α ₄ .

In the end mill having the above configuration, since the helix angles θ ₁ , θ ₂ , θ ₃ , and θ ₄ of the peripheral blades 11 to 14 are different from each other, the circumferential spacing between the peripheral blades 11 to 14 also depends on the end mill body. 1 becomes continuously different from the distal end to the proximal end. As a result, cutting forces of different magnitudes are applied to the end mill body 1 at irregular time intervals.
Therefore, according to the end mill of this example, due to the synergistic effect with the action due to the unequal twist described above,
An even better vibration damping effect than that shown in FIGS. 1 and 2 can be obtained.

Further, FIGS. 6 and 7 show a third embodiment of this invention, and the end mill of this example has four peripheral blades 21, 22, 23, 24 with equal helix angles θ. They are formed at positions that divide the circumference unequally. That is, the outer peripheral blade 2
1 and the peripheral blade 22 and the peripheral blade 23 and the peripheral blade 24 are spaced apart from each other by an interval L ₂ in the circumferential direction, and the peripheral blade 22 and the peripheral blade 23 and the peripheral blade 24 and the peripheral blade 21 are spaced apart from each other by the distance L _{1 .} are formed with a shorter distance L ₂ between them.

The radial rake angle of the peripheral blades 21 and 23 is a negative angle −α ₅ , and the other peripheral blades 22 and 2
The radial rake angle of No. 4 is a negative angle _-α6 . Here, these radial rake angles −α ₅ , −α ₆
The magnitude of each is −α ₅ <−α ₆ .

Even with the end mill of this example having the above configuration, the same effects as those shown in FIGS. 3 to 5 can be obtained.

In addition, in the above-mentioned examples, explanations have been given of those having four peripheral blades 3 to 4, 11 to 14, and 21 to 24, but the invention is not limited to this, and it is possible to have a plurality of peripheral blades. If so, the same can be applied.

[Effects of the invention] As explained above, the end mill of this invention has the following advantages:
Since the radial rake angle of at least one of the plurality of peripheral blades is set to a different angle from the radial rake angle of the other peripheral blades, cutting forces of different magnitudes may act on the end mill body. become. Therefore, for this end mill,
Since regular periodic vibrations that cause resonance do not occur in the end mill body, the cutting edge does not break at any rotation speed, and excellent finished surface roughness can be obtained.

[Brief explanation of the drawing]

Figures 1 and 2 show the first embodiment of the end mill of this invention, with Figure 1 being a front view and Figure 2 being a front view.
The figure is a side view, Figures 3 to 5 show a second embodiment of this invention, Figure 3 is a front view, Figure 4 is a side view, Figure 5 is a side development view of the peripheral blade, Figures 6 and 7 show a third embodiment of this invention.
FIG. 6 is a front view, and FIG. 7 is a side development view of the peripheral blade. 1... End mill body, 2... Bottom blade, 3, 4,
5, 6, 11, 12, 13, 14, 21, 22,
23, 24...Peripheral cutter, α ₁ , α ₂ , α ₃ , −α ₄ , −α ₅
，
−α ₆ ... Radial rake angle, θ, θ ₁ , θ ₂ , θ ₃ , θ ₄
...Torsion angle.

Claims (1)

[Scope of utility model registration request] In an end mill in which a plurality of peripheral blades extending in the axial direction are formed on the outer periphery of the tip of the end mill body, the radial rake angle of at least one of the peripheral blades is different from the radial rake angle of the other peripheral blades. An end mill characterized by being set at an angle.