JP2558677Y2 - End mill - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end mill which has no chatter even when used at a high cutting speed and has good durability.

[0002]

2. Description of the Related Art End mills are widely used for processing dies and various parts.
In particular, roughing with a large cutting amount is performed as the first step of the cutting process, and the end mill for roughing is required to have no chatter even at a large cutting amount and cutting speed.

[0003] Conventionally, various end mills for roughing which have improved rake and flank shapes have been proposed as chatter-free roughing end mills. Did not. In addition, chipping easily occurs due to the large cutting amount,
It is desired to extend the life.

Accordingly, an object of the present invention is to provide an end mill which is free from chatter even at a large cutting amount and cutting speed and is suitable for roughing with a long life.

[0005]

Means for Solving the Problems In view of the above object, as a result of intensive research, the present inventor has made a rake face on each of the outer peripheral blades so as to make the shape of the cutting edge part corrugated, and also to make a shape from the tool tip part. By making the rake angle fluctuation pattern a cycle consisting of a relatively gentle change and a relatively rapid change, it was discovered that chatter does not occur even at a large cutting amount and cutting speed, and that the life is long. I came up with the present invention.

That is, in the end mill of the present invention, the rake face of each outer peripheral blade is subjected to corrugation processing so that the shape of the cutting edge becomes corrugated, and the rake angle is formed along the outer peripheral blade from the tip end. Periodically fluctuating, the fluctuation pattern of the rake angle, a cycle having a region that decreases with a relatively gentle curve and a region that increases with a relatively steep curve repeats, and in a relatively gentle curve region The rake angle starts at 0 ° or a relatively small negative angle and gradually decreases toward the negative minimum value. And then rapidly returns to the departure angle.

[0007]

FIG. 1 shows a side view of an end mill according to an embodiment of the present invention, and FIG. 2 shows the end mill as viewed from the tip. The end mill of this embodiment has four blades, and each outer peripheral blade 1 has a rake face 2 and a flank 3. In addition, the groove | channel 5 is formed in the front-end | tip part so that the length of the bottom blade 4 may differ from four pieces. For this reason, chatter when cutting with the bottom blade 4 is prevented.

As shown in FIG. 3, in an arbitrary cross section of the end mill, the rake angle α has a shape different for each peripheral blade. This is because, as will be described later, the pitch of the rake angle of each outer peripheral blade and the phase shift of the rake angle between the outer peripheral blades are set so as to be an indivisible ratio (ratio that is not an integer). is there.

The rake face 2 and the flank face 3 are processed into a corrugated surface, but as shown in FIG. 4, the waveform of the rake face 2 has a relatively large fluctuation width. The waveform of the flank 3 is not shown in the drawing because the fluctuation width is relatively small. Although the waveform of the rake face 2 and the waveform of the flank face 3 are both effective in preventing chatter, the effect of the rake face 2 is overwhelmingly large.

Due to the waveforms on the rake face 2 and the flank face 3, the cutting edge 6 having a shape as shown in FIG.
Is obtained. The rake angle and the relief angle periodically fluctuate along the waveform pattern of the cutting edge 6, and FIG. 5 specifically shows the state.

As shown in FIG. 5, the rake angle α is, in order from the tip end of the end mill, a region A of relatively gradual change.
And a cycle of a relatively rapidly changing region B are repeated. Specifically, in the area A, the angle changes from a point a having 0 ° or a relatively small negative rake angle α to a point b having a negative minimum value with a gentle curve, and in the area B, the point b From a point d to a point of a positive maximum value in a relatively steep curve, and returns from the point d to the point a rapidly. Thus, the curve of the rake angle α in one cycle is asymmetric.

On the other hand, the clearance angle β changes with a relatively smaller fluctuation width than the rake angle α. The clearance angle β is the rake angle α
Unlike, the curves in each cycle need not be asymmetric.

With respect to the rake angle α, the size at the point b (the minimum point) is -6 ° to -20 °, preferably -10 ° to
−15 °, and the magnitude at the point d (maximum point) is +3
° to + 10 °, preferably + 3 ° to + 6 °. Note that the point a is preferably set to 0 ° to -6 °. The pitch of the rake angle α varies depending on the size and the number of teeth of the end mill. For example, in the case of a 4-flute end mill having a diameter of 6 to 20 mm, the pitch is preferably 0.8 to 3 mm. At this time, the ratio of the region A / the region B is preferably about 2 to 1. In addition, diameter 6
In the case of a 3-flute end mill of ~ 20 mm, the pitch is 0.1 mm.
5 to 2 mm is preferred. At this time, the ratio of the region A / the region B is preferably about 2 to 1.

On the other hand, with respect to the clearance angle β, the fluctuation range (difference between the maximum value and the minimum value) is 3 ° to 30 ′, preferably 3 ° to 1 °.
The pitch is preferably about 0.8 to 3 mm for the same four-flute end mill as described above, and is preferably about 0.5 to 2 mm for a three-flute end mill.

The rake angle α is determined by the cutting edge 6 of the outer peripheral blade 1.
When the straight line along the rake face 2 coincides with the radial direction of the end mill, the angle is 0 °, when the rake face 2 extends at an acute angle is minus, and when the rake face 2 extends at an obtuse angle, it is plus. The clearance angle β is defined as 0 ° when the tangent at the cutting edge of the outer peripheral blade 1 and the straight line along the flank 3 coincide.

For the purpose of preventing chatter, each outer peripheral edge (point 11, FIG. 3 in FIG. 3) in an arbitrary cross section of the end mill is used.
It is preferable that the rake angles α of 12, 13, 14) are not the same. For this purpose, the ratio is set so that the pitch of the rake angle α of each outer peripheral blade and the phase shift of the rake angle α between the outer peripheral blades cannot be divided. For example, if the pitch of the rake angle α is 1 mm, and if the phase shift is 0.3 mm, the waveform of the cutting edge portion 6 of each outer peripheral blade 1 will not return to the same state within the range of the blade length. Further, if the phase of the clearance angle β in each of the outer peripheral blades 1 is shifted, the clearance angle β of each of the outer peripheral blades in an arbitrary cross section of the end mill.
They cannot be the same.

The present invention is not limited to a four-flute end mill,
For example, it can be applied to a three-flute end mill. Also in this case, each outer peripheral edge has a corrugated rake face and a flank face 3, and the rake angle α and the flank angle β change periodically in a pattern similar to that shown in FIG.

It is preferable that the rake angle α of the outermost edge, which is the most distal, is set to the size of the point c in order to improve the bite into the work material.

Although the reason why the above-mentioned effect is obtained in the present invention is not always clear, since the change pattern of the rake angle α is asymmetric in each cycle, cutting by the outer peripheral edge becomes locally non-uniform. This is probably because the non-uniformity cancels out as a whole, and a stable cutting is obtained.

When the end mill according to the present invention is used, the Cr-Cr—
When a work material made of a steel material such as Mo steel is cut, the life is increased 1.5 times or more without causing chatter. This is considered to be because chipping of the outer peripheral edge was significantly reduced.

[0021]

As described in detail above, the end mill of the present invention has an outer peripheral edge whose rake angle fluctuates periodically, so that there is no chatter even at a large cutting amount and cutting speed. In addition, since the chips are scattered well and chipping of the cutting edge due to biting of the chips is prevented, the life is significantly increased. Such an end mill is particularly suitable for roughing.

[Brief description of the drawings]

FIG. 1 is a side view showing an end mill according to an embodiment of the present invention.

FIG. 2 is a plan view showing a tip portion of the end mill of FIG.

FIG. 3 is a sectional view taken along line XX of FIG. 1;

FIG. 4 is a partially enlarged view showing a wave-shaped cutting edge portion of an outer peripheral blade of the end mill.

FIG. 5 is a graph showing a variation pattern of a rake angle and a clearance angle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Outer peripheral blade 2 ... Rake surface 3 ... Flank surface 4 ... Bottom blade 5 ... Groove 6 ... Blade edge

Claims (4)

(57) [Scope of request for utility model registration] 1. The rake face of each outer peripheral edge is subjected to corrugation processing.
An end mill with the shape of the cutting edge part having a waveform
The rake angle from the tip along each peripheral cutting edge is cyclically varied, the variation pattern of the rake angle has a region decreases at a relatively gentle curve, and an area for increasing a relatively steep curve Ri name repeatedly cycle, relatively boiled
In gentle curves, the rake angle is 0 ° or relatively small
Start from a negative angle and go to a negative minimum
In a relatively steep curve area,
A sharp curve from the minimum value of minus to the maximum value of plus
An end mill , which increases and then returns sharply to said starting angle . 2. The end mill according to claim 1 , wherein
The negative minimum value in each cycle of the rake angle is in the range of −6 ° to −20 °, and the positive maximum value is ++
An end mill having a range of 3 ° to + 10 ° and a pitch of each cycle of 0.8 to 3 mm. 3. The end mill according to claim 1, wherein the clearance angle also fluctuates from the tip portion along each outer peripheral edge, and a variation width of the clearance angle is smaller than a variation width of the rake angle. End mill characterized by the following. 4. The end mill according to claim 1 , wherein a phase of the rake angle of each of the outer peripheral blades is such that the rake angle of each of the outer peripheral blades is not the same in an arbitrary cross section of the end mill. An end mill characterized by being set to a value that is indivisible to the pitch of the end mill.