JP2003225823A - End mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an end mill with superior machining accuracy and a long service life even when it is used in high-speed cutting by enhancing a fastening force and runout accuracy and improving the cutting performance of an end mill used by elongating a protrusion in three-dimensional curved surface cutting, five-axis cutting or the like for cavity cutting or the like. <P>SOLUTION: In the end mill, a cutting edge is detachably fixed by shrinkage fitting to a body comprising an adapter and a shank. It is characterized in that the cutting edge has a cutting edge part provided around an axis in one end and a tapered shaft in another end, the cutting edge part side-end diameter of the tapered shaft is smaller than the diameter of the cutting edge part, and a taper of ≤1/50 becomes thinner toward the shank side of the body. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to an end mill, and more particularly to an end mill used with a long protrusion in three-dimensional curved surface cutting such as cavity cutting and five-axis cutting.

[0002]

2. Description of the Related Art A solid end mill has been conventionally used for three-dimensional curved surface cutting such as cavity cutting using an end mill and five-axis cutting with a long cutting path. However, due to the nature of work, a small diameter end mill is projected long. In many cases, even though the cutting edge that actually contributes to cutting is small, it becomes large as a whole, and the life of the cutting edge becomes the life of the end mill as a whole, compared to the size of the cutting edge. The cost was high. Therefore, JP 2000-12
Recently, an end mill in which a blade portion is detachably fixed to a main body by shrink fitting as disclosed in Japanese Patent No. 6918 has also been used.

[0003]

However, the conventional shrink-fitting end mill has a straight shaft portion in the blade portion and a straight hole portion in the main body adapter portion, and the straight shaft portion and the straight hole portion are fitted together. I am fit,
The part that is actually fixed is not limited to the whole straight shaft, especially the cutting edge part side of the straight shaft part. There was also a problem in terms of accuracy. This is done by utilizing the thermal expansion and contraction of the mating part, and shrinkage of the adapter part varies depending on the heating temperature and cooling rate, which affects the fixing force and tool runout accuracy. It is because it exerts. In addition, this type of end mill that uses a long tool protrusion amount, especially when used in high-speed cutting,
There is a problem in that the blade portion is easily moved and sometimes falls off, inferior run-out accuracy, chipping and chipping occur, and the life is short.

[0004]

SUMMARY OF THE INVENTION The present invention has been made on the basis of the background as described above, and three-dimensional curved surface cutting such as cavity cutting,
To improve the cutting force by increasing the sticking force and runout accuracy of an end mill that is used with a long protrusion in 5-axis cutting, etc., and to provide an end mill that has a long life even when used in high-speed cutting and has excellent processing accuracy. To aim.

[0005]

In order to achieve the above object, the present invention provides an end mill in which a blade portion is detachably fixed to a main body composed of an adapter portion and a shank portion by shrink fitting. The portion has a cutting edge portion provided around the axis at one end and a tapered shaft portion at the other end, and the end diameter of the tapered shaft portion on the cutting edge side is smaller than the blade diameter of the cutting edge portion, It is an end mill characterized by having a taper of 1/50 or less that narrows toward the shank portion side. The adapter portion of the main body has a straight hole portion at one end thereof or a tapered tapered hole portion that is smaller than the taper of the tapered shaft portion of the blade portion and becomes narrower toward the shank portion side. Alternatively, the length of the tapered hole portion is longer than the length of the tapered shaft portion of the blade portion, and the inner diameter of the end portion of the straight hole portion or the tapered hole portion on the side of the cutting edge portion is smaller than the end diameter of the blade portion on the cutting edge portion side. An end mill having a diameter larger than a shank portion side end diameter of a taper shaft portion, and a taper shaft portion of the blade portion and a straight hole portion or a taper hole portion of the main body are fitted and fixed to each other.

[0006]

By applying the present invention, the fixing force and the runout accuracy are improved, and even when used in high speed cutting, the tool life is long and excellent processing accuracy can be obtained. First, according to the present invention, since the blade portion has the taper shaft portion that becomes thinner toward the shank portion side of the main body, at the time of shrinkage fitting, the ring shape is surely sequentially provided from the cutting edge side in the tool axial direction. It will stick. Here, a part of the taper shaft portion of the blade is finally fixed, but even if the fixing area is small, the surface is surely fixed, and in the direction perpendicular to the tool axis, the adapter portion The variation in shrinkage of the adapter will be suppressed as much as possible, and it will be less affected by the variation in shrinkage of the adapter part due to the heating temperature and cooling rate of shrink fit, the fixing force and runout accuracy will be improved, and stable cutting can be performed. Even when used for high-speed cutting, it has a long life and excellent processing accuracy can be obtained.

Here, since the end diameter of the taper shaft portion on the cutting edge portion side is smaller than the blade diameter of the cutting edge portion, the portion to be shrink-fitted can be specified from the end portion of the taper shaft portion on the cutting edge portion side. Moreover, by making the tip diameter of the main body adapter portion smaller than the blade diameter of the cutting edge portion, there is an effect of preventing interference with the work material during cutting. Also, the taper of the taper shaft of the blade becomes smaller toward the shank of the main body.
The reason why it is set to 50 or less is to make the direction of the sticking force as close as possible to the direction perpendicular to the tool axis, and when it exceeds 1/50, the force tends to be applied in the direction of pushing out the blade portion. Here, the reason why the shank portion is made thinner toward the shank portion side is in consideration of the ease of attaching and detaching the blade portion.

Next, in the body adapter, the shape of the hole of the body adapter that fits the taper shaft of the blade is straight or smaller than the taper of the taper shaft of the blade and narrows toward the shank. The reason why the taper is made is to securely secure the taper shaft portion of the blade portion in the ring axial direction from the side of the cutting edge portion in the tool axial direction. Further, the length of the straight hole portion or the tapered hole portion is made longer than the length of the taper shaft portion of the blade portion in order to specify the portion to be shrink-fitted from the end of the taper shaft portion on the side of the cutting blade portion. Further, the inner diameter of the end on the cutting edge side of the straight hole or the tapered hole is smaller than the diameter on the cutting edge side of the taper shaft of the blade, and is larger than the end diameter of the tapered shank on the shank side. This is to make the interference in the radial direction of the tool appropriate by fitting.

Here, the blade portion has a taper shaft, and the inner diameter of the straight hole portion or the tapered hole portion of the main body adapter on the cutting edge side is smaller than the end diameter of the taper shaft portion of the blade portion on the cutting edge side. Since it is larger than the end diameter of the tapered shaft portion on the shank side, it can be fixed by a press-fitting method as well as a shrink fitting method. Also, the shape of the taper shaft portion of the blade portion and the straight hole portion or the taper hole portion of the main body adapter portion is the shape of the portion which is actually fixed by shrink fitting, and the other portions do not interfere with each other. Instead, it is within the scope of the present invention. Furthermore, in the main body, even if the adapter part and shank part are made of the same steel material and are integrated, the shank part is made of cemented carbide or steel material with high rigidity, and is connected to the adapter part by screws, spigots, brazing or other methods. It may be a combination. This connection is for accurate integration without disturbing the rotational balance, and the run-out is small even if the end-neck dimension of the end mill is lengthened and the protrusion is increased, and the runout is small. Deflection and deformation can be prevented. In particular, when a cemented carbide is used, vibration resistance is improved, chatter vibration during cutting is suppressed, and life is improved in addition to the above. Hereinafter, description will be made based on examples.

(Example 1) FIG. 1 shows Example 1 of the present invention, in which a blade portion 1 and a main body 2 are detachably fixed by shrink fitting, a blade diameter of 10 mm, a blade length of 15 mm, a total length of 165 mm, and two balls. It is an end mill with a blade, and the cutting edge part 3 has TiAl
It is coated with N film. FIG. 2 shows the blade portion 1, which is made of ultrafine particle cemented carbide and has a length of 35 mm,
The taper shaft portion 4 for fixing is provided at the end of the cutting edge portion 3,
Taper is 1/100, cutting edge 3 side end diameter is 6.01 mm,
The length is 20 mm. FIG. 3 is a main body 2 of Example 1 of the present invention and is an axial sectional view thereof. The main body 2 is composed of an adapter portion 5 and a shank portion 6, and has a tip diameter of 9.8 mm and extends linearly from the tip to the end portion of a straight shank having a diameter of 16 mm with a gradient of 3 °. The length of the taper under neck is 59 mm, and the length including the shank 6 is 15 mm.
It is 0 mm. The adapter part 5 is made of special steel having a high coefficient of thermal expansion and is within a range of 35 mm from the tip of the main body 2. A straight hole portion 7 that fits into the tapered shaft portion 4 of the blade portion 1 is provided, and its inner diameter is 5.99 mm and its length is 25 mm.
Further, the shank portion 6 is a K-type cemented carbide, and both are connected by a spigot and a screw. When manufacturing this end mill, the main body is finished with the special steel part and the cemented carbide part fastened together, so concentricity and cylindricity are 0.00
The value is 2 mm or less, which is a sufficient value for high-speed cutting.

Further, as Conventional Example 2, the blade has a straight shaft, the main body adapter has a straight hole, and the straight shaft and the straight hole are fitted together in a straight manner. A shrink-fit end mill was prepared, and a cutting test was performed together with Example 1 of the present invention to evaluate the cutting state. Here, as a cutting state, a cutting sound is a sound generated during cutting due to chatter and vibration of the tool, and is influenced by tool rigidity and cutting conditions. The surface quality is evaluated comprehensively by measuring the roughness, peeling and gloss of the cut surface. All of these are affected by tool mounting rigidity and cutting edge runout accuracy when the cutting characteristics of the cutting edge are the same. As for the cutting conditions, a structural carbon steel S50C material was used for the work piece, and the protruding amount from the machine tool was fixed at 75 mm, and the cutting speed was 150 m / min and the feed rate was 1600.
mm / min, incision 1 mm, pick feed 3 mm, dry straight cutting.

As a result, Example 1 of the present invention had good cutting noise and good surface properties, whereas Conventional Example 2 had a higher cutting noise than Example 1 of the present invention, and the machined surface had a chamfered surface. Was observed, and there were several chippings on the cutting edge. Inventive Example 1 showed remarkable improvement in cutting noise and surface quality as compared with Conventional Example 2, and it could be confirmed that tool mounting rigidity and cutting edge runout accuracy were significantly improved.

(Embodiment 2) Next, as Embodiment 3 of the present invention, a blade having the same shape as that of Embodiment 1 of the present invention and the same blade portion as that of Embodiment 1 of the present invention is used, and the main body is as shown in FIG. In addition, the adapter part 5 of the main body 2 becomes thinner toward the shank part 6 side 1 /
A taper hole 8 having a 500 taper and an inner diameter on the cutting edge side end of 5.99 mm was manufactured, and the same cutting test and evaluation as in Example 1 were performed. As a result, Example 3 of the present invention is
More stable cutting was possible as compared with Example 1 of the present invention. this is,
It is presumed that the fixing area is wider than that of the first example of the present invention, and the tool mounting rigidity and the run-out accuracy of the cutting edge are further improved.

Although the end mill of the present invention example showed a superior value as compared with the conventional example, it is obvious that it is due to the synergistic effect of the good fixation rigidity and the fixation accuracy obtained in the present invention example. Although the ball end mill has been illustrated in the above embodiments, it goes without saying that a square blade or any other shape can be applied.

[0015]

As described above, according to the present invention, in the three-dimensional curved surface cutting such as the cavity cutting and the five-axis cutting, the sticking force and the runout accuracy of the end mill used with a long protrusion are improved to improve the cutting performance. It was possible to provide an end mill that has a long life even when used in high-speed cutting and has excellent machining accuracy.

[Brief description of drawings]

FIG. 1 shows a side view of Example 1 of the present invention.

FIG. 2 shows a side view of the blade of FIG.

3 shows an axial cross section of the body of FIG.

FIG. 4 shows an axial sectional view of Example 3 of the present invention.

[Explanation of symbols]

1 blade 2 body 3 cutting edge 4 Taper shaft 5 Adapter part 6 Shank part 7 Straight hole 8 Taper hole

Claims (2)

[Claims] 1. An end mill in which a blade portion is detachably fixed to a main body composed of an adapter portion and a shank portion by shrink fitting, the blade portion having a cutting edge portion provided at one end around an axis, It has a taper shaft portion at the end, and the taper shaft portion has a taper of 1/50 or less whose end diameter on the cutting edge portion side is smaller than that of the cutting edge portion and becomes narrower toward the shank portion side of the main body. An end mill that is characterized by 2. The end mill according to claim 1, wherein the adapter portion of the main body has a straight hole at one end thereof or a taper that is smaller than the taper of the taper shaft portion of the blade portion and becomes narrower toward the shank portion side. The straight hole or the tapered hole has a length longer than the taper shaft length of the blade, and the inner diameter of the end of the straight hole or the tapered hole on the cutting edge side is the taper of the blade. It is configured to be smaller than the cutting edge side end diameter of the shaft portion and larger than the shank portion side end diameter of the taper shaft portion, by fitting the taper shaft portion of the blade portion and the straight hole portion or the taper hole portion of the main body. An end mill characterized by being fixed.