JPS6140413Y2 - - Google Patents

Description

[Detailed explanation of the idea]

This invention relates to an indexable end mill having four or more cutting tips. Conventionally, as this type of indexable end mill, the ones shown in FIGS. 1 and 2, or FIGS. 6 and 7, respectively, are known. The indexable end mill shown in FIGS. 1 and 2 has a
Four chip discharge grooves F ₁ extending in the axial direction,
F ₂ , F ₃ , F ₄ are formed respectively, and chip discharge grooves F ₁ ,
Cutting blade chips a ₁ , a ₂ , a 3 : c ₁ , c ₂ , c _{3 for} three pieces each are placed on the wall facing the rotation direction of F ₃ in the chip evacuation groove.
Two cutting blade chips b ₁ , b ₂ :d ₁ , d ₂ are detachably mounted on the wall facing the rotational direction of F ₂ and F ₄ by tightening bolts 2, respectively. In addition, as shown in FIG. 3, the cutting edge tip a ₁ ,
a ₂ , a ₃ and cutting blade tips c ₁ , c ₂ , c ₃ are arranged at the same distance from the tip of the end mill body 1, respectively, and cutting blade tips b ₁ , b ₂ and cutting blade tips d ₁ , d ₂ are arranged in the same way. However, when cutting is performed using such an indexable end mill, there is a problem in that vibrations are large, which deteriorates the cutting surface and also causes damage to the cutting edge portion of the cutting tip. The applicant investigated the cause of the vibration and came to the conclusion that the main cause was the continuous cutting in the axial direction of the cutting tip. That is,
Since the end mill is cantilevered with one end supported, the frequency of vibration of the end mill body 1 differs depending on whether an impact is applied to the front end side or when an impact is applied to the rear end side. Therefore, when a shock is applied to the tip side and then to the rear edge side, the vibration caused by the impact applied to the tip side is canceled out by the impact applied to the rear edge side, and the rear edge side Only the vibrations caused by the impact applied to the object remain, and the vibrations are not amplified by the two impacts. However _, in the above _- mentioned conventional end mill, as shown in _FIG . It is designed to be cut. In such continuous cutting, there is little difference in the frequency of vibration of the end mill body 1 due to the impact of each cutting edge tip a ₁ , a ₂ , a ₃ , and therefore the vibration of the end mill body 1 is amplified, causing vibration during cutting. The end mill was beginning to vibrate a lot. In addition, in this product, the three cutting blade tips a ₁ , a ₂ , a ₃ and the cutting blade tips c ₁ , c ₂ , c ₃ are arranged at the same distance from the tip of the end mill body 1. The cutting blade tips b ₁ , b ₂ and the cutting blade tips d ₁ , d ₂ for the two pieces are also the same, so as shown in FIG. As a result, the number of cutting edges is twice as many as actually required, which increases tool costs.Furthermore, the number of chip evacuation grooves F ₁ , F ₂ ,
Since F ₃ and F ₄ extend in the axial direction of the end mill body 1, the rigidity of the end mill body 1 is reduced.
There was a problem that vibration was further promoted. On the other hand, the indexable end mill shown in FIGS. 6 and 7 has tip pockets P ₁ to P ₁₂ formed on the outer periphery of the tip of the end mill body 11, and a wall surface facing the rotation direction of these tip pockets P ₁ to P ₁₂ . It is made up of circular cutting blade tips q ₁ to _{q 12} that are removably attached to each other by tightening bolts 12, and these cutting blade tips q ₁ to _{q 12} are rotated in the direction of rotation as shown in FIG. The cutting edges q 1 to q 12 are arranged on an imaginary spiral L having a positive lead angle at a pitch interval of πD/4+α (D is the diameter of the end mill), thereby aligning each cutting edge tip q ₁ to q ₁₂ in the axial direction and They are shifted in the circumferential direction to disperse the impact caused by each cutting edge tip q ₁ to q ₁₂ . However, in this case as well, there are three cutting blade chips that are adjacent to each other in the circumferential direction, for example, cutting blade chips q ₁ ,
Q ₅ and q ₉ continuously cut in the axial direction as the end mill rotates, which has the disadvantage of large vibrations. In addition, in this product, each cutting edge tip q ₁ ~
Since q ₁₂ is placed on the virtual spiral L, the 10th
As shown in the figure, each cutting edge tip q ₁ to _{q 12} cuts a different part of the workpiece W, but
Since circular chips are used, if the axial pitch interval between axially adjacent cutting blade chips is too wide, large irregularities will occur on the cutting surface of the workpiece W. Therefore, it is necessary to narrow the pitch interval in the axial direction between cutting edges that are adjacent to each other in the axial direction, which increases the number of required cutting edges and increases the tool cost. Furthermore, as the number of cutting blade chips increases, the number of chip pockets increases, causing a decrease in the rigidity of the end mill body 11. This idea was made to solve the above problem, and it is possible to suppress the vibration of the end mill body due to the impact caused by the cutting tip during cutting, and also to reduce tool costs and improve the rigidity of the end mill body. The purpose is to provide a throw-away type end mill that can. The feature of this invention is that four or more polygonal cutting tips are arranged so as to satisfy all of the following A to C. A The cutting blade tips are offset from each other in the axial direction and circumferential direction of the end mill body. B. Each cutting edge tip has a rotation locus on a plane including the axis of the end mill main body of the linear portion on the outer circumferential side thereof, which continues in a straight line to form one outer circumferential edge. C The number of each cutting blade tip is the largest when three cutting blade tips adjacent to each other in the rotational direction are arranged in the order of front end - rear end - front end or rear end - front end - rear end. An embodiment of this invention will be described below with reference to FIGS. 11 to 15. Note that FIG. 11 is a partially omitted front view of the indexable end mill according to this invention, and FIG. 12 is a bottom view thereof. Reference numeral 21 in the figure is an end mill main body, and this end mill main body 21 includes a shank portion 21a on the rear end side,
It consists of a blade portion 21b on the tip side. The outer periphery of the blade portion 21b is marked with symbols A, B, C, in order from the tip side.
Four chip pockets with the letter D are formed. On each wall surface of the chip pockets A, B, C, and D facing the direction of rotation, square cutting chips of the same shape and size are removably attached by tightening bolts 22, respectively. As shown in Fig. 13, these cutting blade tips,..., are arranged sequentially in the direction opposite to the rotational direction, with the cutting blade tip located at the most distal side as a reference. . In other words, these cutting blade tips,... When arranged from the leading end to the trailing end,
This is called alternating arrangement. ), and are shifted in the axial direction and circumferential direction of the end mill main body 21, respectively. The pitch interval in the axial direction between cutting blade chips that are adjacent to each other in the axial direction (for example, between the cutting blade chips), that is, the pitch interval from the tip of the straight portion 23 of the cutting blade tip to the tip of the straight portion 23 of the cutting blade tip is all are made equal, and the cutting edge tip (,
, ) is made equal to the length of the straight line portion 23. As shown in FIG. 14, the cutting edges adjacent to each other in the axial direction are
1, the rotation trajectory of the nose portion 24 on one rear end side overlaps with the rotation trajectory of the nose portion 24 on the other tip side, and the rotation trajectory of the straight portion 23 continues in a straight line. It's summery. Therefore, the blade length of the peripheral blade formed by the cutting blade chips, . . . is equal to the sum of the lengths of the straight portions 23. In this case, since each cutting edge tip,,, is the same shape and size,
The blade length of the peripheral blade is also equal to the product of the length of the straight portion 23 and the number of chips. On the other hand, pitch intervals in the circumferential direction between circumferentially adjacent cutting blade tips (for example, between cutting blade tips) are all set to be equal. Therefore, as shown in FIG. 12, when viewed from the bottom, each cutting edge tip,
, , have the same pitch interval in the circumferential direction. However, when cutting is performed using such an indexable end mill, the 14th
As shown in the figure, each cutting blade tip,,,, is designed to cut alternately on the front end side and the rear end side of the end mill body 21, so that the end mill body is affected by the impact when cutting one cutting blade tip. 21
The frequency of vibration of the end mill body 21 differs significantly from the frequency of vibration of the end mill body 21 due to the impact during cutting of other cutting blade tips adjacent to the rear in the rotational direction. Therefore, the vibration caused by the impact of one cutting blade tip is canceled out by the impact of the other cutting blade tip adjacent to the rear in the rotational direction, thereby achieving a high vibration damping effect and reducing the cutting of the end mill body 21. It can suppress the vibrations of time. Moreover, in this embodiment, a plurality of cutting blade tips are not unevenly distributed on a part of the outer periphery of the end mill main body 21 when viewed from the bottom, and the cutting blade chips .
are arranged at equal pitches, so a large unbalanced load does not act on the end mill body 21.
This prevents the end mill main body 21 from greatly bending and vibrating, and the vibration of the end mill main body 21 can be further suppressed. In addition, according to this indexable end mill, the cutting edge tip forming the outer peripheral edge,
Since they are offset from each other in the axial direction, a peripheral edge with a long edge length can be obtained with a certain cutting edge tip. In other words, the number of cutting edges can be reduced to obtain a constant edge length of the peripheral edge,
This makes it possible to reduce tool costs.
In particular, in this embodiment, the length of the outer peripheral cutter is made equal to the sum of the lengths of the straight portions 23 of each cutting edge tip, . The blade length can be made the longest. Moreover, as the number of cutting blade chips decreases, the number of chip pockets decreases, thereby improving the rigidity of the end mill body. Next, another embodiment of this invention shown in FIGS. 16 to 20 will be described. Here, only the arrangement of the cutting blade tips will be described, and the same parts as in the above embodiment will be denoted by the same reference numerals, and their explanation will be omitted. Moreover, it goes without saying that the same effects as those of the above-mentioned embodiments can be obtained in the embodiments described below. The indexable end mills shown in FIGS. 16 to 21 are those in which the length of the peripheral cutting edge is required to be long, and therefore the number of cutting blade chips is eight. These eight cutting blade tips are
Straight section 2 of cutting blade tips adjacent in the rotational direction (for example, cutting blade tips; and;...)
The pitches are arranged so that the sum of all the pitch intervals between the tips of 3 becomes the maximum, and under such conditions, the minimum pitch interval among the pitch intervals is as large as possible. By arranging them in this manner, the cutting blade tips are perfectly alternately arranged. In the indexable end mill of this embodiment, the minimum pitch interval in the axial direction between the cutting blade tips adjacent to each other in the rotational direction is made as large as possible, so that a higher vibration damping effect can be obtained. Alternatively, sufficient space can be secured between adjacent tip pockets in the rotational direction, thereby preventing the tip pockets from being formed in a state where they intersect with each other. The rigidity can be further improved, and the improved rigidity of the end mill main body 21 and the large vibration damping effect combine to suppress the vibration of the end mill main body 21 even more effectively. Note that the arrangement of the cutting blade tips that maximizes the sum of the pitch intervals in the axial direction between cutting blade tips that are adjacent to each other in the rotation direction, and also maximizes the minimum pitch interval in the axial direction, is as follows. When there are 4 to 10 blade chips, there are things like the following table. In the following table, the pitch interval represents the pitch interval in the axial direction between the tips of the straight portions 23, 23 of circumferentially adjacent cutting blade tips.

[Table] In this case, when the number of chips is an even number, all the cutting edges are completely alternately arranged, and when the number of chips is an odd number, the cutting edges are placed in a completely alternating arrangement. Except for the blade tips, they are arranged alternately. It goes without saying that the arrangement may be reversed to that shown in the above table, for example, when the number of chips is four. Further, as an arrangement for simply maximizing the number of alternate arrangements, there is the following arrangement. In this case as well, as in the table above, when the number of chips is even, the chips are completely alternated, and when the number is odd, they are placed in 1
Except for one place, the other parts are arranged alternately. A reverse arrangement is also possible. The following table is similar to the previous table.

[Table] As is clear from these two tables,
Arranging more than two cutting chips so as to maximize the number of alternating chips means that when the number of chips is an even number, they are completely alternated, and when the number of chips is an odd number, all but one are alternated. In the above embodiment, the shapes of the cutting chips are square and of the same shape and size, but this is not limited to this, and each cutting chip may have a different shape. Also, the shape may be a polygonal shape such as a triangle, rhombus, parallelogram, or pentagon. Furthermore, either negative chips or positive chips may be used. The arrangement of the cutting chips is not limited to the above two tables, and what is important is to maximize the number of alternating chips. The number of chips is also
The number of the chip pockets may be 11 or more. Furthermore, the pitch between the chips in the circumferential direction when viewed from the bottom may be unequal.
1. In this case, it is preferable that they do not cross each other in order to prevent a decrease in the rigidity of the end mill body 21. As described above, according to the throw-away end mill of this invention, four or more polygonal cutting tips are A. shifted from each other in the axial and circumferential directions of the end mill body, B. the rotation locus of the linear portion on the outer periphery side on a plane including the axis of the end mill body is continuous on a straight line to form one peripheral force, C. three cutting tips adjacent in the rotation direction are arranged in a front end-rear end-front end or rear end-front end-front end arrangement.
Since the arrangement satisfies all of the above requirements, namely, that on the rear end side and that the number of arrangements is the largest, it is possible to suppress vibration during cutting, and it is also possible to obtain effects such as reducing tool costs and improving the rigidity of the end mill body.

[Brief explanation of the drawing]

Figures 1 to 5 show an example of a conventional indexable end mill, and Figure 1 is a front view thereof;
Fig. 2 is a bottom view of the end mill, Fig. 3 is a developed view showing the arrangement of the cutting tips, Fig. 4 is a drawing showing the cutting order of the cutting tips, and Fig. 5 shows the cutting process and the main body of the end mill. Figures 6 to 10 show other examples of conventional throw-away type end mills, and Figure 6 is a partially omitted front view of the end mill. 7
The figure is a bottom view, Figure 8 is a developed view showing the arrangement of the cutting blade tip, Figure 9 is a view similar to Figure 4, and Figure 10 is a view similar to Figure 4.
11 to 15 show an embodiment of this invention, FIG. 11 is a partially omitted front view, FIG. 12 is a bottom view, and FIG. 13 is a diagram similar to FIG. 5.
The figure is a developed view showing the arrangement of the cutting blade tips, Figure 14 is a diagram showing the cutting order of the cutting blade tips, and Figure 15 is a diagram showing the cutting process status, as well as the arrangement of the cutting blade tips on a plane containing the axis of the end mill body. 16 to 21 show other embodiments of this invention, and FIG. 16 is a partially omitted front view,
Fig. 17 is a bottom view, Fig. 18 is a view similar to Fig. 13, Fig. 19 is a view similar to Fig. 14, and Fig. 18 is a view similar to Fig. 14.
FIG. 0 is a diagram similar to FIG. 15, and FIG. 21 is a diagram showing the cutting process and the arrangement of the cutting blade chips when viewed from the shank side. 21... End mill body, 23... Straight section,
,,,,,,,... Cutting tip.

Claims (1)

[Claims for Utility Model Registration] 1. On the outer periphery of the tip of the rod-shaped end mill body,
In a throw-away end mill in which four or more polygonal cutting tips are removably attached and have a straight section and a nose section and form an outer peripheral edge, the cutting tips are arranged in the following A to C manner.
A throw-away end mill that is characterized by being arranged to satisfy all of the following. A The cutting blade tips are offset from each other in the axial direction and circumferential direction of the end mill body. B. Each cutting edge tip has a rotation locus on a plane including the axis of the end mill main body of the linear portion on the outer circumferential side thereof, which continues in a straight line to form one outer circumferential edge. C The number of each cutting blade tip is the largest when three cutting blade tips adjacent to each other in the rotational direction are arranged in the order of front end - rear end - front end or rear end - front end - rear end. 2. The peripheral edge formed by the rotation locus is
Utility model registration claim 1, characterized in that the length of the blade is approximately equal to the sum of the lengths of the straight parts forming the outer peripheral edge of each cutting edge tip.
Throw-away end mill described in section. 3. Each of the cutting edge tips has a shape in which the total sum of the pitch intervals in the axial direction between the tips of the straight parts of the circumferentially adjacent cutting edge tips is the largest, and the circumferentially adjacent cutting edge According to claim 1 or 2 of the utility model registration claim, the blade tip is arranged so that the smallest pitch interval in the axial direction between the tips of each straight portion of the blade tip is the largest. Throwaway end mill listed.