JP2003094228A - Radius end mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radius end mill which can perform high feed rate machining by improving chipping resistance of a cutting edge at a rounded corner of a radius end mill. SOLUTION: In the radius end mill having a rounded corner cutting edge of an approximately 1/4 circle at the corner portion of the tip end of the end mill, a straight line segment passing a 0 deg. point and a 90 deg. point of the rounded corner cutting edge with respect to an end cutting edge side in the axial view of the end mill inclines by 10 deg. to 50 deg. with respect to a straight line segment passing the center of the end mill and the 0 deg. point, and the maximum value of projecting height of a convex curve with respect to the straight line segment passing the 0 deg. point and the 90 deg. point is 15% to 30% of the radius of the rounded corner cutting edge.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a radius end mill used for deep engraving of contour lines such as dies.

[0002]

2. Description of the Related Art Ball end mills have been generally used for deep contouring of metal molds. Recently, there has been a strong demand for high efficiency cutting, and a radius end mill has been used instead of the ball end mill.
Compared to ball end mills, radius end mills have a shorter length at which the cutting edge contacts the work material, and with ball end mills the cutting speed cannot be obtained because the end mill tip is on the end mill axis. Radius end mills are suitable for high efficiency cutting because they have low cutting resistance and good sharpness because they can obtain sufficient cutting speed. Further, regarding the radius end mill, many improvements have been made according to the purpose of use and the like.
Japanese Patent No. 246508 discloses an example in which a corner R blade is reinforced,
Further, Japanese Patent Laid-Open No. 11-216609 discloses an example in which the machinability is improved.

On the other hand, in the processing of dies and the like, there are processing such as corner processing and processing such as deep engraving with a large amount of tool protrusion, and chatter vibration is likely to occur during cutting.
A method of lowering the feed rate that is easy to process in the C program is adopted. The method of lowering the feed rate not only reduces the machining efficiency, but also has less effect of suppressing chatter vibration,
Since the feed rate per blade decreases in proportion, the number of contact between the cutting edge and the work material increases, and wear progresses faster. Also, there is a method of reducing the cutting speed, which has a high effect of suppressing chatter vibration,
With this alone, the feed rate decreases proportionally, and the machining efficiency decreases in any case, so recently, as a means for performing high-efficiency cutting, the cutting speed is reduced, but the feed rate is increased.
That is, high-feed cutting that extremely increases the feed amount per blade is used.

[0004]

However, in the above radius end mill, if the feed amount of one blade is extremely increased,
There is a problem that the cutting load is concentrated on the corner R blades, the strength of the corner R blades cannot withstand the cutting load, and the chip is broken to reach the end of its life. In particular, when performing high feed cutting in machining with a large cutting amount such as rough machining, the cutting resistance is large,
Since the defects are more likely to occur, the cutting conditions have to be further lowered, and the state cannot be called high efficiency cutting.

[0005]

SUMMARY OF THE INVENTION The present invention has been made based on the above background, and it is an object of the present invention to provide a radius end mill which improves the fracture resistance of a corner R blade and enables high feed cutting. To aim.

[0006]

Therefore, the present invention is
In a radius end mill having an approximately 1/4 arc-shaped corner R blade in the end mill tip corner portion, a line segment passing through R0 degrees and 90 degrees of the corner R blade in the axial direction of the end mill has a line segment passing through the center of the end mill and the R0 degree. 1 for a line segment that passes through degrees
The maximum value of the protrusion amount of the convex shape with respect to a line segment that is inclined at 0 ° to 50 ° and passes through R0 ° and 90 ° of the edge line of the corner R blade is 15% to 30% of the corner R radius. It is a radius end mill characterized by.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, the inclination angle is from 10 degrees.
By setting it to 50 degrees, from the corner R blade's R0 degree to 90 degrees
The cutting will be gradually carried out gradually, the sharpness can be maintained, and the cutting resistance can be lowered. Inclination angle is 1
If it is less than 0 degree, the effect of tilting is small, and if it exceeds 50 degrees, the thickness of the corner R blade itself becomes thin, and the cutting resistance in the axial direction of the end mill causes a defect, and more preferably, 20 Is 40 to 40 degrees, and more preferably 20 to 30 degrees for three-dimensional machining because the cutting resistance in the axial direction of the end mill increases.

Next, the reason why the maximum value of the protruding amount of the convex shape is set to be 15% to 30% of the radius of the corner R is that if it is less than 15%, the effect of forming a convex curve is small and the sharpness is further improved. This is because the improvement cannot be improved, and if it exceeds 30%, the convex curve may become distorted, the convex curvature is large, and the strength is reduced. Preferably, it is 20% to 30%. When the position of the maximum value of the protrusion amount is set to R30 to 50 degrees, the convex curve may be distorted if it is outside the above range, and the sharpness is inferior, and it is connected to the end blade or the outer peripheral blade. Is not smooth, edges are likely to occur, cutting resistance increases, and abnormal wear is likely to occur. As described above, since the cutting edge strength and cutting resistance are reduced, it is possible to perform high-feed cutting with a large 1-flute feed by suppressing chipping of the corner R blade even in large-cutting operations such as rough cutting. Became.

Here, in order to further reduce the occurrence of the edge portion, the gashing of the bottom blade and the gashing of the corner R blade are performed in a series of processing, and the corner ridges of the corner R blade and the bottom blade have one convex edge. A curved line may be formed to improve the fracture resistance of the corner R blade. Further, in order to perform high efficiency cutting, it is advantageous to have a large number of blades, but in the case of a work piece with a corner portion, in a multi-blade end mill with four or more blades,
Since there are simultaneous cutting edges at the corners and chatter vibration due to resonance is likely to occur, the number of blades is preferably three. Further, it goes without saying that a long life can be achieved by applying a hard coating such as TiAlN or a Cr-based lubricating coating.
Hereinafter, the present invention will be specifically described based on Examples.

(Example 1) Ultrafine particle cemented carbide, blade diameter 1
Comparative Example 1 using a radius end mill having a radius of 2 mm, a radius of corner R of 2 mm, and three blades, and an inclination angle of 3 shown in FIG.
Is 5 degrees, invention example 2 is 10 degrees, invention example 3 is 20 degrees, invention example 4 is 30 degrees, invention example 5 is 40 degrees, invention example 6 is 50 degrees, and comparative example 7 is 60 degrees.
Of high degree is manufactured, and HRC4 is used for the work material as cutting specifications.
0 prehardened steel, length 150mm, width 18m
m, depth 30 mm, groove-shaped pocket processing with a side wall angle of 3 degrees, rotation speed 2600 rotations, feed speed 1250 mm / m
in, 1 blade feed amount was 0.16 mm / blade, end mill axial pitch was 0.6 mm, tool protrusion length was 65 mm, contouring was performed by air blow, and the damaged state was observed.

As a result, the invention examples 2 to 6 have a depth of 30 m.
Up to m, that is, one shape could be processed, and the original processed shape was obtained. In particular, in the inventive examples 3 and 4, chatter vibration was very small, and the cutting state was stable. In addition to slight micro-chipping being observed in Inventive Example 6, the wear width was small due to normal wear and the machined surface was good, but Inventive Example 5 was slightly
A rattling vibration occurred and the cutting noise was loud. In Comparative Example 1, both chatter vibration and cutting noise were larger than at the beginning of cutting,
In the damaged state of the end mill after the completion of the 1-shape machining, a large chipping was found on the corner R blade, and the initially machined shape was not obtained. Further, in Comparative Example 7, the thickness of the corner R blade itself became too thin, and the corner R blade was chipped at the initial stage of cutting, and the life was reached.

(Embodiment 2) With the same specifications as the radius end mill of the present invention example 1, the maximum value 4 of the convex shape of the corner R blade 1 shown in FIG.
5%, 20% as Inventive Example 9 and 2 as Inventive Example 10
5%, Inventive Example 11: 30%, Comparative Example 12: 3
5%, that is, 0.3 mm, 0.4 mm, 0.5 mm, 0.
6 mm and 0.7 mm were manufactured, and the same cutting test and evaluation as in Example 1 were performed. As a result, Example 8 of the present invention
In the present invention examples 9 to 11, chatter vibration was very small, the cutting state was stable, and the damaged state of the end mill was In Comparative Example 12, a slight amount of chipping was observed, and the wear width was small due to normal wear, and the processed surface was good.

(Embodiment 3) With the same specifications as the radius end mill of the present invention example 1, the position of the maximum projection amount 4 of the corner R blade 1 shown in FIG. Example 14 is R30 degree part, and invention example 15 is R35.
Example 1, Example 40 of the present invention has R40 degrees, Example 17 of the invention has R45 degrees, Example 18 of the invention has R50 degrees, and Example 19 of the invention has R55 degrees. The same cutting test and evaluation were performed. as a result,
For all end mills, up to a depth of 30 mm, ie
It was possible to machine one shape, and the original machined shape was also obtained. Here, in particular, in Examples 14 to 18 of the present invention, chatter vibration was very small, the cutting state was stable, the end mill damage state was normal wear, the wear width was small, and the machined surface was good. Inventive Example 13 is a connection with the outer peripheral blade, and Inventive Example 19
Has an edge portion connected to the bottom blade, and the convex curve of the corner R blade is slightly distorted, which causes some chatter vibration and chipping of the edge portion.

(Example 4) With the same specifications as the radius end mill of the present invention example 1, as a present invention example 20, a series of the mash processing of the bottom blade 2 and the corner R blade 1 shown in FIG. Example 1 was carried out in which the corner ridges of the corner R blade 1 and the bottom blade 2 formed one convex curve.
The same cutting test was performed. As a result, not only chipping is suppressed due to the absence of edge parts, chip discharge is improved, chatter vibration is reduced by one layer, the cutting state is more stable, and the end mill damage state after the completion of 1-shape machining is The normal wear also reduced the wear width by one layer.

[0015]

From the above results, by applying the invention of the present application, it is possible to use the corner R blades even in the machining such as rough machining, which is used for the deep engraving of contour lines such as dies, and the like. It was possible to provide a radius end mill capable of performing high-efficiency cutting with a large amount of feed by one blade.

[Brief description of drawings]

FIG. 1 shows an axial view of an example of the invention.

[Explanation of symbols]

1 corner R blade 2 bottom blade 3 Corner R blade tilt angle 4 Maximum amount of protrusion 5 R0 degree 6 R 90 degrees

Claims (2)

[Claims] 1. A radius end mill having a corner R blade having a substantially quarter arc shape at the end corner portion of the end mill, wherein a line segment passing through R0 degrees and 90 degrees of the corner R blade in the axial direction of the end mill is With respect to a line segment passing through the center of the end mill and the R0 degree, the maximum value of the protruding amount of the convex shape with respect to the line segment passing through the R0 degree and 90 degrees of the cutting edge ridge of the corner R blade is A radius end mill having a corner radius of 15% to 30%. 2. The radius end mill according to claim 1, wherein the position of the maximum value of the protrusion amount of the corner R blade is R30.
Radius end mills characterized by being located at degrees to 50 degrees.