JPH0453850Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to an end mill used when performing groove processing or stepped processing on a workpiece.

[Prior Art] Generally, when performing groove processing or stepped processing on a workpiece, various types of end mills are used, each of which has a plurality of cutting edges formed along the axial direction on the outer periphery of the tool body. There is.

FIGS. 4 and 5 show, among this type of end mill, a conventional end mill called a solid type in which the cutting blade is integrally formed on the outer periphery of the end mill body.

This end mill 1 has a substantially cylindrical end mill body 2 made of high-strength steel, cemented carbide, etc., and a plurality of cutting blades 3 (four in the figure) each extending approximately spirally along the axial direction on the outer circumference of the end mill body 2. It is formed integrally in a striped manner. Here, these plurality of cutting blades 3 are formed at equal intervals along the circumferential direction of the end mill main body 2, dividing the circumference into four equal parts, as shown in FIG. There is. Furthermore, front cutting edges 4 are formed on the tip surface of the end mill main body 2, and are connected to the cutting edges 3 and extend approximately to the center of the tip surface.

The conventional end mill 1 having the above configuration is rotated around an axis and fed in the axial direction or in a direction perpendicular to the axis, so that the cutting edge 3... and the front cutting edge 4... The side and bottom surfaces of the workpiece are cut.

[Problems to be solved by the invention] However, in the conventional end mill 1 described above, since the cutting blades 3 are formed at equal intervals along the circumferential direction of the end mill body 2,
During cutting, these cutting blades 3 sequentially apply an impact to the workpiece surface at equal time intervals, and the reaction force of this impact acts on the end mill body 2 as a constant periodic vibration. The end mill main body 2 resonates with this constant period of vibration, which causes chatter in the end mill 1 itself and the workpiece material, resulting in damage to the cutting blade 3 and the finish of the workpiece surface. There was a problem that the surface accuracy deteriorated.

In addition, the chatter of the end mill 1 and the workpiece increases the cutting resistance of the cutting blades 3, resulting in an increase in the mechanical power required for cutting.

The purpose of this invention is to solve the problems that conventional end mills have.

[Means for Solving the Problems] The end mill of this invention has a plurality of cutting edges extending parallel to each other from the distal end toward the proximal end on the outer periphery of the end mill body. At a position where the circumference of the end mill body is divided into unequal parts, that is, in a plane perpendicular to the axis of the end mill body, the angle formed by the line connecting at least one of the adjacent cutting blades and the axis is The angle is different from the angle formed by the line connecting each of the adjacent cutting edges and the axis. Note that the cutting blades being parallel here means that the circumferential spacing between the cutting blades does not change from the tip to the base of the end mill body, that is, the cutting blades are parallel in the developed view. Say something.

[Function] In the end mill having the above configuration, the plurality of cutting blades are formed at positions that divide the circumference of the end mill body into unequal parts, so that the interval between the cutting impacts that these cutting blades give to the workpiece surface is reduced. becomes irregular.
Therefore, the reaction force of this impact acting on the end mill body also becomes irregular, so that resonance does not occur in the end mill body, and therefore, no vibration occurs in the end mill itself or the work material. Further, since no chatter is generated in the end mill or the workpiece, there is no increase in the cutting resistance of the cutting blade due to the chatter. The reason why the cutting blades are parallel in this invention is that if they were not parallel, the chip discharge grooves formed between the cutting blades would be extremely wide and narrow. In particular, more chips are discharged from the chip evacuation groove between the cutting blades where the angle of the line connecting each of the cutting edges and the axis of the end mill is larger than the others; If the groove is narrower at the base end of the end mill, there is a risk of chip clogging.

[Example] Fig. 1 shows an example of an end mill of this invention, and parts common to those shown in Figs. 4 and 5 are given the same reference numerals and their explanations are omitted.

In the end mill 10 of this example, the cutting blade divides the circumference into equal parts along the circumferential direction of the end mill body 2 in a plane perpendicular to the axis O of the end mill body 2 shown in FIG. formed in position. That is, if the cutting blades are respectively 11a, 11b, 11c, and 11d in clockwise order along the circumferential direction of the end mill body 2, then the lines connecting the cutting blades 11a, 11b and the axis O, respectively, are Both the angle and the angle formed by the line connecting the cutting edges 11c, 11d and the axis O are both α ₁ , and the angle formed by the line connecting the cutting edges 11b, 11c and the axis O, respectively, and the cutting edge 11
The angles formed by the lines connecting d and 11a with the axis O are both angles α ₂ which are larger than the angle α ₁ . Note that these cutting edges 11a, 11b, 11
c and 11d are formed parallel to each other, and therefore, each cutting edge extends from the distal end of the end mill body 2 toward the proximal end while maintaining the above-mentioned angular relationship.

Here, the angles α ₁ and α ₂ are desirably set so that the difference between the angle α ₁ and the angle α ₂ is within the range of 5° to 20°. That is,
If the difference between the angles α ₂ and α ₁ is less than 5°, the unequal amount between each cutting edge will be too small to obtain a sufficient effect, and if the difference exceeds 20°, each cutting edge will be too small. This is because the unbalance of the cutting resistance acting on the blade becomes too large, which may lead to damage to the cutting edge, which is particularly subjected to large cutting resistance.

Therefore, in the case of such an end mill 10, since the cutting edges 11a, 11b, 11c, and 11d are formed at positions that divide the circumference of the end mill body 2 into unequal parts, these cutting edges 11a, 11
The intervals between the impacts b, 11c, and 11d give to the surface to be machined during cutting become irregular. Therefore, the reaction force of this impact acting on the end mill body 2 also becomes irregular, so that resonance does not occur in the end mill body 2. Therefore, the end mill 10 itself and the workpiece material do not generate chatter, so there is no risk of chipping of the cutting edge, and in addition, the finished surface accuracy of the machined surface can be improved.

Furthermore, since no vibration occurs in the end mill 10 itself or the workpiece material, there is no increase in the cutting resistance of the cutting blade caused by this vibration, thereby reducing the mechanical power required for cutting. I can do it.

Furthermore, in FIG. 1, there is a cutting edge 11b which has the longest cutting edge length and receives a larger cutting load than other cutting edges, and a cutting edge 11a preceding this cutting edge 11b.
If the angle α ₁ between the end mill 1 and the
0 It is also possible to make the cutting balance as a whole uniform. By the way, in the end mill having such a configuration, the angle α2 formed by the line connecting the axis O and the cutting blades 11d and 11a and the line connecting the axis O and the cutting blades 11b and 11c is equal to the angle α2 between the axis O and the cutting blades 11a and 11c.
b and the axis O and the cutting blades 11c and 11d.
Therefore, the distance between the cutting blades in the circumferential direction of the end mill is also set to be larger than the angle α2 formed by the line connecting the cutting blades 11d, 11a and the cutting blades 11b, 1.
The distance 1c is larger than the distance between the cutting edges 11a, 11b and the cutting edges 11c, 11d. For this reason, the amount of chips produced by each cutting edge also varies depending on the cutting edge 11a,
The number of cutting edges 11c is greater than that of cutting edges 11b and 11d.

On the other hand, in the end mill 10 having the above configuration, each cutting edge is formed in parallel, so the angle α2 is
Between the cutting edges 11d and 11a and the cutting edges 11b and 11
The chip evacuation groove formed between c
It is larger than the chip evacuation groove formed in between, and extends from the tip end of the end mill 10 to the base end side. That is, over the entire length of the cutting edge, the chip evacuation grooves of the cutting blades 11a, 11c, which generate a large amount of chips, are different from those of the cutting blades 11b, 1, which generate a small amount of chips.
The groove is formed wider than the chip discharge groove 1d, which prevents chip clogging and the like from occurring and facilitates smooth chip discharge.

By the way, if the cutting edges are not formed parallel, the chip evacuation groove narrows at the base end of the end mill body, and when a large amount of chips generated at the tip side moves toward the base end, the groove width will increase. There is a big risk that it will become insufficient and cause a blockage.

In the above embodiment, the angles α ₁ , α ₁ and the angles α ₂ , α ₂ between the cutting edges facing each other with respect to the axis O were set to be equal to each other, but this is not limiting, and the total The angles between the cutting edges may be set to different angles such that the difference between the maximum value and the minimum value is within the range of 5° to 20°. In this case, as mentioned above, by setting the angle between the longest cutting edge and the preceding cutting edge to be small, it is possible to obtain an even better effect of making the overall cutting balance more uniform. can.

Further, in the above embodiment, only the so-called solid type end mill 10 has been described, but the invention is not limited to this. Cutting blade tips are provided at the same positions as the cutting blades 11a, 11b, 11c, and 11d on the outer periphery of the end mill body 2. Similar effects can be obtained even if the parts are fixed together by brazing or the like. Furthermore, the number of cutting edges is not limited to four, and the end mill may have more or less than four cutting edges.

[Experiment example] The end mill according to this invention is a solid type made of cemented carbide, and each of the four cutting edges has a first
The one with an outer diameter of 20φ formed at the positions α ₁ = 81° and α ₂ = 99° in the figure is also used as a conventional end mill, which is a solid type made of cemented carbide with the same diameter and the four cutting edges are mutually connected. Those formed at equal intervals along the circumferential direction were prepared.

Then, each of these two end mills performs one-sided cutting of the workpiece (material: SCM440) under the conditions listed below, and each end mill receives each cutting force in the X, Y, and Z directions (unit: Kg). ) was measured. Here, the X component force is the component force in the direction along the feed direction, the Y component force is the component force in the direction perpendicular to the side surface of the workpiece, and the Z component force is the direction perpendicular to the bottom surface of the workpiece material. The components of force are shown respectively.

Cutting conditions: Cutting speed: 30m/min (rotation speed: 1194r.pm) Table feed: U = 200, 400 Feed per tooth: Sz = 0.04, 0.08 Depth of cut: 10mm, cutting width: 1,6mm 2nd The figure shows the experimental results of the end mill according to this invention, and FIG. 3 shows the experimental results of the conventional end mill.

From Figures 2 and 3, it can be seen that in conventional end mills, the values of component forces in all directions change at a constant cycle, and the amplitudes (strengths of impact) are large. It can be seen that in the end mill according to this invention, the changes in the values of all component forces are irregular, and the values and amplitudes of each component are also smaller.

[Effects of the invention] As explained above, the end mill of this invention has the following advantages:
A plurality of cutting edges extending from the distal end toward the proximal end are formed on the outer periphery of the end mill body at positions that divide the circumference of the end mill body into unequal parts.
There is no occurrence of chatter in the end mill itself or the work material, and thus the finished surface accuracy of the machined surface can be improved. Furthermore, since no chatter occurs in the end mill or the workpiece, there is no increase in the cutting resistance of the cutting blade due to this chatter, and therefore the mechanical power required for cutting can be reduced. . Furthermore, by forming each cutting edge parallel to each other, a chip evacuation groove corresponding to the amount of chips generated is formed along the entire length of the cutting blade, which has the advantage of facilitating smooth chip evacuation. You can also get it.

[Brief explanation of the drawing]

Figure 1 is a front view showing an embodiment of the end mill of this invention, Figure 2 is a diagram showing the cutting force during a cutting test using the end mill according to this invention, and Figure 3 is a diagram showing the cutting force during a cutting test using a conventional end mill. The diagrams illustrating the cutting force, FIGS. 4 and 5, show a conventional end mill, with FIG. 4 being a side view and FIG. 5 being a front view. 2... End mill body, 10... End mill,
11, 11a, 11b, 11c, 11d...cutting blades.

Claims (1)

[Claims for Utility Model Registration] (1) In an end mill in which a plurality of cutting blades are formed on the outer periphery of a substantially cylindrical end mill body from the tip end toward the base end, the cutting blades are:
They are formed so that they are parallel to each other, and in a plane perpendicular to the axis of the end mill body, an angle formed by a line connecting at least one of the adjacent cutting blades and the axis line is different from that of the other adjacent cutting blades. An end mill characterized in that the end mill is formed at an angle that is different from the angle formed by a line connecting the cutting blade and the above-mentioned axis. (2) Utility model registration claim No. 1, characterized in that the difference between the maximum and minimum angles formed by the lines connecting each of the adjacent cutting edges and the axis is within the range of 5° to 20°. The end mill according to item 1.