JP3833975B2 - Radius end mill for high feed cutting - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an improvement of a radius end mill used for contour processing of a die or the like, and more particularly to high feed cutting.
[0002]
[Prior art]
Conventionally, ball end mills are generally used for contour processing of dies and the like. Recently, the demand for high-efficiency cutting has increased, and a radius end mill has been used instead of the ball end mill. The radius end mill has a shorter cutting edge length where the cutting edge comes into contact with the work material compared to the ball end mill, and the ball end mill cannot obtain the cutting speed because the end mill tip is on the end mill axis. On the other hand, since a radius end mill can obtain a sufficient cutting speed, it has a low cutting resistance and good sharpness, and is suitable for high-efficiency cutting. Further, the radius end mill has been improved in a number of ways depending on the purpose of use thereof. For example, JP-A-7-246508 discloses an example in which a corner R blade is reinforced, and JP-A-11-216609. Japanese Patent Publication discloses an example in which the machinability is improved.
[0003]
When machining dies, etc., there are machining of corners and machining of large tool protrusions such as deep engraving, and chatter vibration is likely to occur during cutting. The method is taken. The method of lowering the feed rate not only reduces the machining efficiency but also has the effect of suppressing chatter vibration, and the single blade feed amount decreases proportionally, increasing the number of contact between the cutting edge and the work material, and the progress of wear. Becomes faster. In addition, there is a method of reducing the cutting speed, which has a high chatter vibration suppressing effect, but with this alone, the feed speed is reduced proportionally, and in any case, the machining efficiency is lowered, so recently, as a means for performing high-efficiency cutting, Although the cutting speed is lowered, the feed speed is increased, that is, high feed cutting that extremely increases the one-blade feed amount has begun to be used.
[0004]
[Problems to be solved by the invention]
However, in the radius end mill, when the feed rate per blade is increased, the cutting load is concentrated near the boundary of the corner R blade, and the strength of the corner R blade cannot withstand the cutting load, and the life due to chipping or chipping is lost. There was a problem of reaching. In addition, when high-feed cutting is performed, the cutting resistance increases and the thickness of the chips increases, which makes it difficult for chips to be discharged to the outside, causing the chips to bite, and causing chipping and chipping. As a countermeasure, the feeding speed is lowered.
[0005]
[Object of the present invention]
The present invention has been made based on the background as described above, and improves the chipping resistance of the corner R blade and improves the discharge of the chips generated by the corner R blade. An object of the present invention is to provide a radius end mill that makes it possible.
[0006]
[Means for Solving the Problems]
Therefore, in the present invention, in a radius end mill having a corner R edge having a substantially arc shape at the end mill tip corner, the intersection of the corner R edge and the bottom edge of the end mill is A, and the corner R edge and the end mill When the intersection point of the outer peripheral blade is B, the rake face of the corner R blade passes through the intersection points A and B, and the rake face of the corner R blade is cut from the intersection point A to the intersection point B. convex curve der towards is, intersection point a, the maximum protrusion of the convex curve to the line segment AB connecting the B is, high feed, characterized in that located in the intersection point a side of the midpoint of the line segment AB This is a radius end mill for cutting.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In high-feed cutting that increases the feed amount per tooth, the cutting amount in the tool axis direction is 35% or less of the corner radius, and when performing high-feed cutting that increases the feed amount per blade, It occurs from the vicinity of the intersection A due to the phase relationship of the cutting edges, and flows obliquely upward, that is, in the vicinity of the intersection B. Therefore, in order to combine the corner R blade with strength and good machinability, in the present invention, the corner R blade is raked in a cross-sectional view of the rake face of the corner R blade passing through two points A and B. The surface is a convex curve from the intersection A to the intersection B, the cutting edge strength is improved, chips are quickly separated from the rake face, cutting resistance can be reduced, and machinability is improved . As described above, the cross-sectional view of cutting the rake face of the corner R blade through the two points of intersection A and B is the direction of generation and flow of chips, and the shape of the rake face of the corner R blade is This is because it can be observed at a glance. For the convex curve, for the same reason as described above, the greater the curvature of the convex curve, the better the machinability. Therefore, the curvature of the convex curve is gradually changed from the intersection A to the intersection B, and the curvature is increased. Is preferably located on the intersection A side from the midpoint of the line segment AB which is a part mainly involved in cutting, and the average curvature of the convex curve on the intersection A side from the midpoint of the line segment AB That is, it is desirable that the curvature of the approximate arc of the convex curve on the intersection A side is larger than that on the intersection B side. In the vicinity of the maximum protrusion of the convex curve, the length of contact with the chips is shortened and the cutting resistance is reduced, so that the best cutting performance can be obtained. It is also effective that the maximum protruding portion of the convex curve exists at a position of 35% or less of the R radius, that is, the maximum protruding portion of the convex curve is located on the intersection A side from the midpoint of the line segment AB. Since better machinability is obtained, a great effect is obtained in reducing chatter vibration. In high-feed cutting that extremely increases the feed amount per tooth, as described above, the cutting amount in the tool axis direction is 35% or less of the corner radius in a general part. By making the rake face on the intersection A side, which is the part used mainly, into a convex curve, the part used mainly at the time of cutting can surely obtain strength and machinability . A concave portion or a straight portion may exist in the vicinity of the intersection B of the corner R blade, and since this portion is not a portion that is mainly used at the time of cutting, there is little influence in high-feed cutting and is within the scope of the present invention. Needless to say. In the case of high-feed cutting, the cutting load is larger than that of general cutting, and the cutting load is concentrated on a weak portion of the corner R blade as a whole, resulting in a defect. Moreover, when the maximum protrusion part of the convex curve of a rake face exists in the intersection A side, the thickness of the rake face with respect to line segment AB by the intersection A side becomes thicker than the intersection B side. Therefore, from the strength balance, the thickness of the average flank on the intersection B side with respect to the line segment AB may be made thicker than the intersection A side. As a whole, the corner R blade has a good balance of strength and resistance. The deficiency can be improved. In order to obtain the strength of the corner R blade, the rake angle of the corner R blade is preferably a negative angle in the tool radial direction, and the range is preferably −15 ° to −40 ° in consideration of strength and machinability. If the rake angle in the tool radial direction is a negative angle of less than 15 °, the cutting edge strength is insufficient and chipping is likely to occur. If the rake angle in the tool radial direction exceeds 40 °, the cutting edge strength increases, but the cutting performance decreases. Will increase chatter vibrations and cutting surface roughness . The rake angle that balances the strength and machinability of the R blade at a high level is more preferably -20 ° to -35 °. In order to perform high-efficiency cutting, it is advantageous to have a large number of blades. However, in the case of a workpiece with a corner corner, a multi-blade end mill with four or more blades has a simultaneous cutting blade at the corner. It is easy to generate chatter vibration due to resonance, so the number of blades is preferably 3 blades. Needless to say, 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.
[0008]
【Example】
Example 1
FIG. 1 shows a first example of the present invention, which is a radius end mill having a blade diameter of 10 mm, a corner radius R of 2 mm, and a three-blade, made of an ultrafine particle cemented carbide coated with a TiAlN coating. The rake face 2 of the corner radius blade 1 It is the principal part enlarged view seen from the side. Further, FIG. 2 cuts the rake face 2 of the corner R blade 1 through two points of the intersection A of the corner R blade 1 and the bottom blade 3 and the intersection B of the corner R blade 1 and the outer peripheral blade 4 of FIG. It is sectional drawing by a plane, and the rake face 2 of the corner R blade 1 is a convex curve from the intersection A to the intersection B, and the maximum position of the curvature of the convex curve is on the intersection A side 6 from the middle point 5 of the line segment AB. Located, the curvature of the approximate arc of the convex curve on the intersection A side 6 is larger than the midpoint 5 of the line segment AB compared to the intersection B side 7, and the maximum protrusion 8 of the convex curve is larger than the midpoint 5 of the line segment AB. About 10% of the line segment AB is located at the intersection A side 6 and the rake angle of the corner R blade 1 is set to −25 ° in the end mill radial direction. Further, the rake face 2 on the intersection A side 6 in FIG. 2 is formed to be convex. By forming it in a convex shape, the rake face 2 on the intersection A side 6 forms chips, shortens the contact when discharging, and allows smooth chip discharge . The thickness 10 of the flank 9 on the intersection B side 7 in FIG. 2 with respect to the line segment AB is thicker than the intersection A side 6, whereby the strength of the entire corner R blade 1 can be increased. Using Example 1 of the present invention, HRC40 pre-hardened steel was used as the cutting material, the rotation speed was 1680 min-1, the feed rate per tooth was 0.625 mm / tooth, and the feed rate was 4200 mm / min. A pocket process having an axial pitch of 0.6 mm and a tool protrusion amount of 40 mm, a length of 100 mm, a width of 65 mm, a depth of 30 mm and a side wall with a gradient of 3 ° was contoured by air blow, and the damage state was observed . As a comparison, the radius end mills described in JP-A-7-246508 and JP-A-11-216609 described in the prior art are manufactured as the conventional examples 2 and 3 with the same dimensions as the present invention example 1, and the above cutting test is performed. Added to. In Example 1 of the present invention, chatter vibration is very small even in the pocket corner portion, and the cutting state is stable, and the tool damage state after the completion of one shape machining is normal wear and the wear width is up to 30 mm. There were few and the processed surface was also favorable. On the other hand, in the conventional example 2, since the feed amount per blade is large, chipping occurs at the time of the third pass machining in which the cutting in the tool axis direction is 1.8 mm, and chatter vibration becomes large at the time of pocket corner partial machining. The cutting noise was loud, and the damaged state of the tool after completion of one-shape machining was already lost due to the chipping of the corner R blade, and the original machining shape could not be obtained. Further, in Conventional Example 3, chipping occurs at the corner R blade at the initial stage of cutting, chatter vibration increases, and when 30% of the pocket processing shape is processed, that is, when the depth is 9 mm, chipping increases and the service life is increased. It became.
[0009]
(Example 2)
As Example 4 of the present invention, the same specifications as in Example 1 of the present invention were produced, in which the maximum protruding portion of the convex curve was located on the intersection B side from the midpoint of the line segment AB. The same cutting was performed. As a result, up to a depth of 30 mm, that is, one-shaped machining was possible, and the tool damage state after machining was normal wear without causing chipping, but slightly chatter vibration was generated compared to Example 1 of the present invention. However, traces of chatter vibration were seen on the machined surface.
[0010]
【The invention's effect】
From the above results, by applying the present invention, the radius end mill improves the chipping resistance of the corner R blade and improves the discharge of chips generated by the corner R blade, thereby enabling high-feed cutting. Could be provided.
[Brief description of the drawings]
FIG. 1 is an enlarged view of a main part of Example 1 of the present invention.
FIG. 2 is a cross-sectional view through intersections A and B in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Corner R blade 2 Rake face 3 Bottom blade 4 Peripheral blade 5 Middle point 6 of line segment AB Intersection A side 7 Intersection B side 8 Maximum protrusion 9 Flank 10 Thickness with respect to line segment AB Corner R blade and bottom blade intersection B Intersection of corner R blade and outer peripheral blade

Claims (1)

In a radius end mill having a corner radius R edge at the end mill tip corner, the intersection point of the corner R blade and the bottom edge of the end mill is A, and the intersection point of the corner R blade and the outer peripheral edge of the end mill is B. The rake face of the corner R blade is a convex curve from the intersection A to the intersection B in a cross-sectional view passing through the two points of intersection A and B and cutting the rake face of the corner R blade. The radius end mill for high feed cutting , wherein the maximum protrusion of the convex curve with respect to the line segment AB connecting the intersection points A and B is located on the intersection point A side from the midpoint of the line segment AB .

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