JPH0319002B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention provides an end mill body with a
This invention relates to an end mill in which a plurality of cutting edges are formed with unequal twists.

[Conventional technology]

As a conventional end mill of this type,
It is known that a plurality of cutting edges spiraling in the axial direction are formed on the outer periphery of the tip of a large-diameter cylindrical end mill body so as to be unequally twisted with respect to each other, as shown in Japanese Patent No. 5244. .

Since the cutting edges of this end mill are formed in an unequal helix, the cutting force and action time of these cutting edges vary in the circumferential direction. Therefore,
Since periodic vibrations that resonate with the end mill's natural frequency do not occur in the end mill body, the chattering phenomenon that accompanies cutting can be prevented, which has the advantage of improving cutting performance. It will be done.

[Problem that the invention seeks to solve]

However, in the conventional end mill described above, as a result of forming the cutting blades in an unequal helix, the spacing between the cutting blades is different over the entire length of the cutting blades, so when forming the cutting blades on the end mill body, The drawback is that it is difficult to determine the position that should be used as a reference point for polishing, and the manufacture itself requires a great deal of effort and skill.

In addition, the circumferential spacing of these cutting blades at the end on the tip side of the end mill body is also different, so if you try to form a bottom blade that connects to these cutting blades on the tip surface of the end mill body, it will be difficult to prevent vibrations. Even bottom cutting edges, which are less effective, are formed at positions that divide the tip surface unevenly. As a result, feed marks with different intervals are formed on the finished surface of the workpiece to be ground by the bottom blade, resulting in an undesirable appearance.

[Purpose of the invention]

This invention was made in view of the above circumstances,
It is an object of the present invention to provide an end mill that can prevent the occurrence of vibrations and the like due to cutting, and can also provide an excellent finished surface.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention forms a plurality of cutting blades with unequal twists at equal intervals in the circumferential direction of the end mill body at the tip of the end mill body, and at the same time A bottom blade extending in the radial direction on the tip surface of the continuous end mill body is formed so as to equally divide the tip surface.

[Effect]

According to the end mill having the above configuration, since the tips of the cutting blades formed at equal intervals can be used as a reference when forming the cutting blades, processing of these cutting blades is easy.

In addition, the bottom blade, which is formed to equally divide the tip surface of the end mill body, forms feed marks at equal intervals on the surface of the workpiece, so that a good finished surface can be obtained.

〔Example〕

1 to 4 show an embodiment of an end mill according to the present invention, and reference numeral 11 in the figures indicates an end mill main body.

The end mill body 11 is made of high-speed steel, cemented carbide, etc. and has an approximately cylindrical appearance, and has four cutting blades 1 twisted in the axial direction on the outer periphery of its tip.
2, 13, 14, and 15 are formed. Between these cutting edges 12, 13, 14, 15, there are chip discharge grooves 16, 17, 18, 19, respectively.
is formed. Also, this end mill body 1
1, the bottom blade 2 extends from each of the cutting blades 12 to 15 in a radial direction toward the center of rotation.
0, 21, 22, 23 are formed.

Here, the above four cutting edges 12, 13, 14, 1
5 is an end mill main body 11 as shown in FIG.
The tips 12a to 15a of the end mill body 11 are formed at equal intervals B in the circumferential direction of the end mill body 11. And these cutting blades 12
~15 are mutually different torsion angles θ ₁ , θ ₂ , θ ₃ , θ ₄
It is said that By the way, these cutting edges 12 to 15
are formed at equal intervals in the circumferential direction at the tip, and the torsion angles θ ₁ , θ ₂ , θ ₃ , and θ ₄ are set to different angles. As a result, as shown in FIG. In this case, the width of the chip discharge grooves 16 to 19 varies. In this case, if a chip discharge groove with a width dimension that is too narrow is formed, the discharge of chips will be hindered. Therefore, the difference in magnitude of these torsion angles θ ₁ , θ ₂ , θ ₃ , θ ₄ is determined by the difference between the diameter D and the total cutting edge length l when the end mill diameter D is 3 mm to 25 mm.
When the ratio (l/D) is about 3, it is desirable to set the angle to 1° to 5°.

Further, the bottom blades 20 to 23 connected to the cutting blades 12 to 15 are each formed to equally divide the tip surface 25.

Furthermore, the cutting blades 12 to 15 and the bottom blades 20 to 23
There are linear small cutting edges 26, 27, 28, 29 each having a slightly positive axial angle.
is formed. And these small cutting blades 26,
The length dimension L of 27, 28, and 29 is each 1 mm or less.

In the end mill having the above configuration, the tips 12a to 16a of the cutting blades 12 to 16 are arranged at equal intervals B...
These tips 12a
By using the cutting edges 12 to 16a as a reference when forming the cutting edges, the cutting edges 12 to 16 can be easily polished. In addition, since it is easy to form the bottom edges 20 to 23, including during re-sharpening, it is possible to obtain good axial runout accuracy for these bottom edges 20 to 23. 20-23
Since the chisel does not wear out prematurely, a long tool life can be obtained.

In addition, since the bottom blades 20 to 23 are formed on the tip surface 25 of the end mill body 11 so as to equally divide the tip surface 25, equally spaced feed marks are formed on the surface of the workpiece. Combined with the vibration damping effect of the unequal twist end mill, it is possible to obtain a good finished surface. For this reason, although it can be used for high-speed cutting that is prone to vibration and chatter due to its excellent tool rigidity, it has a remarkable effect when applied to end mills made of cemented carbide or cermet, whose cutting edges are prone to chipping. can be obtained.

In addition, a small cutting blade 26 is provided with a slight positive axial angle between the bottom blades 20 to 23 and the cutting blades 12 to 15.
29, it is possible to prevent the corner portion between the bottom blade and the cutting blade from chipping. Also,
By appropriately adjusting the length dimension L of the small cutting blades 26 to 29, the tips 12a to 16a of the cutting blades 12 to 15 are
Since the interval B in can be adjusted, it is possible to easily form the tips 12a to 15a at equal intervals.

In the above embodiments, a solid type end mill made entirely of high-speed steel or cemented carbide was described, but it is also possible to use a brazed type end mill in which a cutting tip with a cutting edge is attached to the end mill body. Good too. Further, in the end mill of the above embodiment, four cutting blades 12 to 16 are formed, but the number of cutting blades is not limited to four as long as it is plural.

Furthermore, although the twisting direction of each cutting edge is set so that the rake angle of the cutting edge is a positive rake angle, the twisting direction may be reversed.

〔Effect of the invention〕

As explained above, in the end mill of the present invention, a plurality of cutting blades with unequal twists are formed at equal intervals in the circumferential direction of the end mill body at the distal end of the end mill body, and The bottom blades that extend in the radial direction on the tip surface of the end mill body are formed so as to equally divide the tip surface, so the ends of the cutting blades formed at equal intervals can be By using it as a reference, it is possible to easily process these cutting edges.

In addition, the bottom blade that equally divides the tip surface of the end mill body forms feed marks at equal intervals on the surface of the workpiece, so a good finished surface can be obtained. Furthermore, if the bottom cutting edge is re-ground by the same amount, the clearance angles will become equal to each other, so high runout accuracy in the axial direction can be obtained, and as a result, a long tool life can be obtained.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention, FIG. 1 is a side view, and FIG. 2 is a side view of FIG. 1.
A line view, FIG. 3 is an enlarged view of the tip, and FIG. 4 is a developed view of the cutting blade. 11... End mill body, 25... Tip surface, 12,
13, 14, 15...cutting blade, 12a, 13a, 14
a, 15a...tip of cutting blade, 20, 21, 22,
23...Bottom blade, 26, 27, 28, 29...Small cutting blade,
θ ₁ , θ ₂ , θ ₃ , θ ₄ ...Torsion angle.

Claims (1)

[Claims] 1 A plurality of bottom blades extending in the radial direction are formed on the tip surface of the cylindrical end mill body, and a plurality of bottom blades extending in the axial direction are formed on the outer periphery of the end mill body, continuous with the bottom blades, and spirally drawn in the axial direction, and at least one helix angle is different from the other. In an end mill in which a plurality of cutting edges are formed with different helix angles, the plurality of cutting edges are formed at equal intervals in the circumferential direction of the end mill body at the tip of the end mill body, and the bottom edge is formed at equal intervals in the circumferential direction of the end mill body. An end mill characterized in that the end face of the end mill body is formed to be equally divided.