JPS6389213A - End mill - Google Patents

Abstract

PURPOSE:To prevent a vibration due to cutting without any drop in tool rigidity by forming a plurality of cutting edges of unequal helix angles at the end of an end mill base at equal intervals in the circumferential direction of an end mill proper. CONSTITUTION:Cutting edges 12, 13, 14 and 15 are so formed as to have different helix angles of theta1, theta2, theta3 and theta4, and the degree thereof are taken as theta1<theta2<theta3<theta4. Cutting edges 12-15 are formed at equal intervals L from each other in a circumferential direction along the ends 12a-15a of the base of an end mill proper 11. By using the ends 12a-15a as reference points for forming cutting edges, therefore, a polishing process can be easily carried out. Also, as said cutting edges 12-15 are formed to have equal intervals L in a circumferential direction near the ends 12a-15a of the end mill proper 11 of which rigidity is most inferior, mechanical bending strength in a circumferential direction can be unified and a rigidity drop at the concerned position can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an end mill in which a plurality of cutting edges are formed in an unequal twist around the outer periphery of the tip of an end mill body.

[Prior art] As a conventional end mill of this kind, the Japanese Patent Publication No. 30-524
It is known that a plurality of cutting blades spiraling in the axial direction are formed on the outer periphery of the tip of a large-diameter cylindrical end mill body, as shown in Publication No. 4, so as to be unequally twisted with respect to each other. .

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, these cutting blades do not generate periodic vibrations that resonate with the natural frequency of the end mill body, making it possible to prevent the chattering phenomenon that accompanies cutting, thereby improving the cutting performance. You will have the advantage of being able to

[Problems to be Solved by the Invention] However, in the conventional end mill described above, as a result of forming the cutting blades in an unequal twist, the intervals between the cutting blades differ from each other over the entire length of the cutting blades. However, when forming a cutting edge on the end mill body, it is difficult to determine the position to be used as a reference point for polishing, and therefore, the manufacturing itself requires a great deal of time and effort.

Furthermore, since the intervals in the circumferential direction of these cutting blades at the end on the base end side of the end mill body are also different, the chips formed between these cutting blades are discharged d1! The inside dimensions will be different. Therefore, the mechanical bending strength of the end mill body becomes non-uniform in the circumferential direction especially in the part where the tool rigidity is poor, and the tool rigidity is further reduced.

For this reason, although there is no problem with relatively large diameter and short cutting edge lengths and light cutting, there is no problem with small diameter and long cutting edge lengths, heavy cutting (deep cutting), and high feed cutting. However, there is a problem in that the end mill itself breaks during cutting at the base end of the end mill body where the end of the cutting blade, which has poor mechanical bending strength, is located.

[Purpose of the Invention] This invention was made in view of the above circumstances, and it is possible to prevent the occurrence of vibrations caused by cutting without reducing tool rigidity. The object of the present invention is to provide an end mill that enables feed cutting.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a plurality of unequally twisted cutting blades at the proximal end of the end mill body. They are formed at equal intervals in the circumferential direction.

[Function] According to the end mill having the above configuration, the ends of the cutting blades formed at equal intervals can be used as a reference when forming the cutting blades, so that processing of these cutting blades is easy.

In addition, near the end of the cutting blade on the proximal end of the end mill body, where the tool rigidity is the lowest, these cutting blades are formed at equal intervals in the circumferential direction, making it possible to prevent a decrease in tool rigidity at that location. can.

[Embodiment] FIGS. 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 integrally formed from high-speed steel, cemented carbide cermet, etc. and has a generally cylindrical appearance, and has four cutting edges 12, 13 twisted in the axial direction on the outer periphery of its tip. 14.15 is formed. Chip discharge grooves 16°17.18.19 are formed between each of these cutting edges 12, 13, 14.15. Furthermore, bottom blades 20.21 and 22.23 are formed on the distal end surface of the end mill main body II, respectively, extending from the cutting blades 12 to 15 toward the center of rotation.

Here, as shown in FIG. 4, the four cutting edges 12.13, 14.15 have different torsion angles θ1. θ7.
θ1. It is formed at θ4. And these angles θ,
The magnitudes of ˜θ4 are θ1×θ2<θ3<θ4, respectively.

Furthermore, these cutting blades 12 to I6 are formed at equal intervals L.. in the circumferential direction of the end mill body 11 at the proximal end 12a=16a of the end mill body It. Incidentally, these cutting edges 12 to 15 are formed at equal intervals in the circumferential direction at the proximal end portions 12a to 16a, and have a twist angle θ1. Ot, 03. As a result of setting θ4 to different angles, as shown in FIG. 4, the chip discharge grooves 16 to 19 have different widths on the tip side of the cutting blade. 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, these torsion angles θ1. θ
2. θ3. As for the difference in size of θ4, when the end mill diameter is 3non to 25 mm, the ratio i/
l in those with D) of about 3.

It is desirable to set the angle to ~5°.

In the end mill having the above configuration, the cutting blades 12 to
16 end mill body summer 1 proximal end 12a = 16
a are formed at equal intervals L... in the circumferential direction of the end mill main body 11, so that these cutting edges 1
By using the ends 12a=16a of Nos. 2 to 16 as a reference when forming the cutting edge, the polishing process can be easily performed.

In addition, near the ends 12a=16a of the cutting blades 12 to 16 on the base end side of the end mill body 11, which has the lowest tool rigidity,
These cutting blades 12 to I6 are formed at equal intervals L in the circumferential direction, similar to a general end mill having equally twisted cutting blades, so that the mechanical bending strength in the circumferential direction can be made uniform. Therefore, it is possible to prevent a decrease in tool rigidity at the relevant portion of the end mill body 11.

Furthermore, the cutting blade 1 is placed at the tip of the end mill body 11, which is most likely to cause vibration and chatter due to cutting resistance from the bottom blade.
Since the difference between the intervals between 2 and 16 is the largest, an excellent vibration-proofing effect can also be obtained.

Therefore, excellent cutting performance without vibration or chatter can be obtained even when applied to items with small diameters and long cutting edges, or items that perform heavy cutting (deep cutting) or high-feed cutting.

For this reason, it can be used especially for high-speed cutting where vibration and chatter are likely to occur due to the tool rigidity, but when applied to end mills made of cemented carbide or cermet, where the cutting edge is easily chipped, there is a noticeable Effects can be obtained.

In addition, in the above example, a solid type end mill made entirely of high-speed steel or cemented carbide was described, but a brazing type in which a cutting tip with a cutting edge is brazed to the end mill body is not applicable. There may be. In addition, the end mill of the above embodiment has four cutting edges! 2~
However, the number of cutting edges is not limited to four as long as it is plural. In addition, 4 cutting edges 1
All twist angles θ1 from 2 to 16. θ1. θ3. Although θ4 is set to a different angle, only the helix angle of the negative cutting edge may be formed to be different from the helix angle of the other cutting edges, and two types of helix angles θ5 and θ may be formed. may be formed alternately in the circumferential direction.

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. In any case, in this invention, if a plurality of cutting blades with unequal twists are formed at equal intervals in the circumferential direction of the end mill body at the proximal end of the end mill body, a similar result can be obtained. Effects can be obtained.

[Effects of the Invention] As explained above, according to the end mill of the present invention,
Since a plurality of cutting blades with unequal twists are formed at equal intervals in the circumferential direction of the end mill body at the proximal end of the end mill body, the ends of the cutting blades formed at equal intervals can be By using this as a reference when forming cutting edges, these cutting edges can be easily processed. In addition, these cutting edges are formed at equal intervals in the circumferential direction near the end of the cutting edge on the proximal end of the end mill body, which has the lowest tool rigidity.
It is possible to prevent a decrease in tool rigidity at this location.

Therefore, it is possible to obtain excellent cutting performance without vibration or chatter, especially when applied to small diameters with long cutting edges, heavy cutting (deep cutting), and high feed cutting. .

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention. FIG. 1 is a side view, FIG. 2 is a fixation view taken along the line ■-■ in FIG. -[[Fixed sectional view, FIG. 4 is a developed view of the cutting blade. 1! ...End mill body, 12a, l3a, l4a, 15a-=-=cutting blade end, θ1. θ,, θ1. θ4...Twist angle.

Claims (1)

[Claims] In an end mill in which a plurality of spiral cutting blades are formed on the outer periphery of the tip of the end mill body, the plurality of cutting blades are connected to the proximal end side of the end mill body. An end mill characterized in that the end portions are formed at equal intervals in the circumferential direction of the end mill body.