JPH05261614A - End mill with nick - Google Patents

Abstract

PURPOSE:To shorten a span of nick start length and thereby capacitate the extent of excellent cutting performance owing to a nick to be sufficiently showable up to the vicinity of the tip of a peripheral cutting edge by giving a maximum nick angle to a nick to be situated in a spot nearest to a tip part of the peripheral cutting edge. CONSTITUTION:In this end mill with a nick, a peripheral cutting edge 1 is intermittently formed therein, while a groove part called a nick 2 is formed in a part where the peripheral cutting edge 1 is not formed. This nick 2 makes chips to be produced by the peripheral cutting edge 1 cut off into small pieces, whereby chip resistance is reduced. In this case, a first nick 23 with a first nick angle theta is formed in a position of nick start length (a) from a tip zero position of the peripheral cutting edge 1. Another nick 22 after that is formed with a second nick angle theta at an equi-interval. In brief, the large nick angle theta1 is given to only the nearest nick 21 to the tip zero position 0 of the peripheral cutting edge 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end mill with a nick, and more particularly to a method of giving a nick angle.

[0002]

2. Description of the Related Art Generally, in an end mill with a nick, an outer peripheral blade 1 is intermittently formed as shown in FIG. 3, and a groove portion 2 called a nick is formed in a portion where the blade is not formed. Since this nick 2 divides the chips generated by the outer peripheral blade 1 into small pieces, the cutting resistance acting on the outer peripheral blade 1 is reduced, and heavy cutting is possible. Α shown in FIG.
Is a twist angle of the outer peripheral blade 1 and is represented by a tilt angle of the outer peripheral blade 1 with respect to the axis E of the end mill in the tangential direction.

Further, FIG. 2 is a view showing the details of the outer peripheral blade 1 and the nick 2, and with the vertical axis Y extending parallel to the axis E as a reference, the tip of the outer peripheral blade 1 extending spirally is taken as the origin O. There is. The spiral outer peripheral blade 1 is developed on a plane and is represented by a straight line. In FIG. 2, the angle θ formed by the direction in which the nick 2 extends and the vertical axis Y is the nick angle.

In the conventional end mill with nick,
The nick angle θ is acute, or obtuse, etc.
There are various types of end mills with nicks, which are properly used depending on the application, but the nick angle θ in each end mill is constant.

Further, the nick 2 closest to the tip side of the outer peripheral blade 1 is formed at a position a distance a from the tip origin O to the nick start length on the Y axis, and the nicks 2 from the tip side onward are the shank side. Toward the nick pitch p at equal intervals. The traveling direction of the outer peripheral blade 1 with the rotation of the end mill is shown by an arrow R in FIG.

For example, in a two-blade or four-blade nicked end mill, the front blades (peripheral blades leading in the rotational direction R) and the next blades (peripheral blades next to the front blade) adjacent to each other in the circumferential direction are used.
In and, the nick start lengths of the respective outer peripheral blades are shifted by a half of the nick pitch p, that is, by p / 2. This is for arranging the nicks in a staggered arrangement so that the next blade can reliably cut the uncut portion of the front blade.

[0007]

In the nicked end mill, the nick pitch p and the nick start length a differ depending on the diameter D of the end mill. For example, for an end mill with a nick having a twist angle α of 30 degrees and a nick angle θ of 20 degrees, the following is defined.

Diameter D Nick pitch p Nick starting length a 3 mm or more and less than 10 mm 2 mm 2.5 mm 10 mm to less than 15 mm 3 mm 4.0 mm 15 mm to less than 20 mm 3 mm 5.0 mm 20 mm to less than 25 mm 4 mm 6.0 mm 25 mm to less than 30 mm 4mm 7.0mm 30mm or more and 50mm or less 5mm 8.0mm

What is defined in this way is the outer peripheral blade 1
To prevent the inconvenience that a back metal of a sufficient size cannot be removed and a weak cutting edge that is imperfect in strength is formed due to the nick being placed in close proximity to the tip origin O of Is. For example, the outer peripheral edge shape shown in FIG. 4 is a case where the first nick 2 is formed at a position of the starting length a ″ that is shorter than the above-mentioned prescribed nick starting length a. The thick back end portion 3 of the outer peripheral blade 1 has a structure in which sufficient back metal cannot be removed, so that the strength is weak and chipping or chipping easily occurs.

Since the nick cannot be formed within the range of the nick start length a of the specified dimension at the tip portion of the end mill, the advantage of the nick cannot be utilized with respect to the cutting performance within this range. Especially for end mills with a diameter of 30 mm or more, since the starting length a is 8 mm, excellent cutting performance due to nick is not exhibited at all in the cutting process with a shallower depth, and the nick is usually not applied. Only the same cutting performance as that of the end mill will be obtained.

In view of the above-mentioned conventional technical problems, the present invention was devised to effectively solve these problems. Therefore, it is an object of the present invention to provide an end mill with a nick in which the starting length of the nick can be made shorter than in the past and the excellent cutting performance by the nick can be sufficiently exerted up to the vicinity of the tip of the outer peripheral blade.

[0012]

An end mill with a nick according to the present invention has the following structure in order to solve the conventional technical problems and achieve the object. That is,
The nick closest to the tip of the peripheral blade has the largest nick angle.

The first nick has a first nick angle and the second nick has a second nick angle that is smaller than the first nick angle. May be formed closest to.

Further, the first nick angle is 45 degrees to 9 degrees.
It is preferable that the range is up to 5 degrees.

[0015]

According to the nicked end mill of the present invention,
Since the nick closest to the tip of the outer peripheral blade is formed with a larger nick angle than other nicks, the first nick (most nick is located at a position shorter than the nick start length specified in conventional end mills with nicks). Even if a nick near the tip point) is formed, a sufficient amount of back metal can be taken for the cutting edge located on the tip side of the outer peripheral blade divided by the nick. Therefore, the nick start length can be shortened while sufficiently providing the strength of the cutting edge on the leading edge side. When the nick start length is shortened, the chip cutting effect by the nick can be obtained even if the cutting depth is shallower than that of the conventional end mill with nick.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to FIG.
Will be described. FIG. 1 is a view for explaining the shape of one outer peripheral blade in a four-blade end mill with a nick for an embodiment of the end mill with a nick according to the present invention, and is similar to FIG. It is a figure.
Therefore, the same configurations will be denoted by the same reference numerals and redundant description will be omitted. The diameter D of the nicked end mill of this embodiment is 30 mm, and the twist angle α of the outer peripheral blade 1 is 30 degrees.

A first nick 2 ₁ having a _first nick angle θ ₁ is formed at a position having a nick start length a'from the origin O of the outer peripheral edge 1. The nick start length a ′ is 5 mm, and the first nick angle θ ₁ is 90 degrees. After that Nick 2 ₂
The second nick angle θ ₂ is provided at equal intervals of the nick pitch p. Nick pitch p is 5 mm, second nick angle θ
₂ is set to 20 degrees. That is, only the nick 2 ₁ closest to the origin O of the tip of the outer peripheral blade 1 has a large nick angle θ ₁ , and the other nicks 2 ₂ have the same nick angle θ ₂ as in the prior art.

In the nicked end mill according to the present embodiment, the nicks 2 arranged on the outer peripheral blades 1 are formed so that the outer peripheral blades 1 adjacent to each other are staggered with respect to each other.
When the outer peripheral blade 1 shown in this figure is used as a reference, the tip ends of the two outer peripheral blades 1 immediately before and after the rotation direction R of the end mill are:
Nick 2 ₁ having a first nick angle theta ₁ is not provided, the start length Nick Nick 2 ₂ having a second nick angle theta ₂ to the position where the a '+ p / 2 is formed. Also,
The other outer peripheral blade 1 has the same nick 2 as the outer peripheral blade 1 having the same shape as the reference of the present drawing.

In the nicked end mill thus constructed, there is no restriction on the nick start length at the tip portion of the outer peripheral blade 1, and when it comes to the entire cutting edge, excellent cutting performance can be obtained by the nick over the entire area. .. As a result, cutting resistance can be reduced. Further, even when the depth is within the conventional nick start length a, that is, within 8 mm in the above case, excellent cutting performance by the nick 2 can be obtained.

The first nick 2 closest to the tip of the outer peripheral blade 1
_As the size of the first nick angle θ ₁ of 1 approaches the angle formed by the bottom surface of the outer peripheral blade 1 and the Y axis, the nick start length a ′ can be shortened. In this sense, the nick angle θ _{1 of the} nick 2 ₁ formed at the position closest to the tip of the outer peripheral blade ₁
Is effectively set in the range of approximately 45 to 95 degrees.

As another embodiment, it is also possible to use an end mill with a nick formed so that the nick angle gradually increases from the blade base side of the outer peripheral blade toward the tip. In this case, all the nick angles of the second and subsequent nicks may gradually change, but a plurality of nick angles may change. Also in these examples, the nick angle of the nick on the leading edge side becomes the largest, and the same effect as that of the above-described examples can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a shape of an outer peripheral edge of an end mill with a nick according to the present invention.

FIG. 2 is an explanatory view showing a shape of an outer peripheral edge of a conventional end mill with a nick.

FIG. 3 is a side view of an end mill with a nick.

FIG. 4 is an explanatory diagram when an incomplete blade is formed at the tip of the outer peripheral blade of the conventional end mill with nick.

[Explanation of symbols]

1 Outer peripheral blade 2 Nick 2 ₁ First nick 2 ₂ Second nick 3 Tip thickness part a Nick start length p Nick pitch θ Nick angle α Peripheral blade twist angle θ ₁ First nick angle θ ₂ Second nick angle R End mill rotation direction D End mill diameter E End mill shaft center Y Peripheral blade reference axis

Claims (3)

[Claims] 1. An end mill with a nick characterized in that a nick (2) located closest to the tip point (O) of the outer peripheral blade (1) has the largest nick angle (θ). 2. A first nick having a first nick angle (θ ₁ ).
(2 ₁ ) and a second nick (2 ₂ ) having a second nick angle (θ ₂ ) smaller than the first nick angle, and the first nick (2 ₁ ) is An end mill with a nick that is formed closest to the tip point (O). 3. The end mill with nick according to claim 2, wherein the first nick angle (θ ₁ ) is in the range of 45 degrees to 95 degrees.