JP2010179424A - Roughing end mill - Google Patents

Abstract

In a roughing end mill having an outer peripheral edge that is wavyly uneven, a load acting on the outer peripheral edge is reduced to suppress an increase in cutting resistance.
Roughing in which an outer peripheral edge 6 is formed on the outer periphery of a tip end portion of an end mill body rotated about an axis O, and a corrugation is formed in the end mill rotation direction T while being twisted in a twisting direction. In the end mill, the waveform formed by the outer peripheral blade 6 in the length along the torsional direction of the outer peripheral blade 6 is concave from the peak portion 6A of the portion where this waveform is convex. The length A up to the valley bottom 6B of the portion to be is made longer than the length B from the valley bottom 6B to the peak 6A of the portion where the waveform on the rear end side in the axis O direction becomes convex next.
[Selection] Figure 2

Description

  The present invention relates to a roughing end mill used for intermediate finishing of a work material, in which an outer peripheral edge that is corrugated in the end mill rotation direction is formed on the outer periphery of a tip end of an end mill body that is rotated around an axis. It is.

  As this type of roughing end mill, for example, Patent Document 1 has a substantially spirally extending cutting edge (outer peripheral cutting edge) positioned at a uniform radial distance from the central axis of the main body, and at least one cutting edge is It has been proposed to have a substantially sinusoidal shape and have rake faces alternately provided with positive and negative rake corners.

  In such a luffing end mill, since the thickness of the chip changes between a convex portion and a concave portion of the sine curve formed by the cutting edge, good chip disposability can be obtained. Further, in this Patent Document 1, if all the sinusoidal blades are located at the same distance from the center axis of the cutting tool (that is, if the height on the radius along the cutting blade is uniform), the workpiece Is also described that the surface is molded relatively smoothly.

JP-A-62-68217

  By the way, in the luffing end mill described in Patent Document 1, the cutting edge is formed in a sinusoidal shape in the direction along the spiral of the cutting edge so as to be uneven in the end mill rotation direction T. Therefore, as shown in FIG. 3, the sine curve is concave from the peak portion 10A of the convex portion of the sine curve formed by the cutting edge 10 toward the rear end side in the axis O direction of the end mill (right side in FIG. 3). The length from the valley bottom 10B to the valley bottom 10B and the length from the valley bottom 10B to the peak 10A of the next convex sine curve toward the rear end side in the axis O direction follow this spiral. The lengths A and B in the same direction are equal to each other at half of one wavelength of the sine curve.

  However, when the length from the summit portion 10A to the valley bottom portion 10B and the length from the valley bottom portion 10B to the next summit portion 10A are viewed in the direction of the axis O of the end mill, the rear end from the summit portion 10A in the direction of the axis O The length b from the valley bottom 10B to the next peak 10A at the rear end side is twisted with respect to the axis O at the twist angle θ with respect to the length a up to the valley bottom 10B on the side. Since the reference line L is uneven, the length becomes longer. That is, assuming that the depth (amplitude of the sine curve) in the direction perpendicular to the reference line L from the peak 10A to the valley bottom 10B of this sine curve is δ, 1 / of the wavelength along the axis O direction of the sine curve. The length a becomes shorter by δ · sin θ than the length of 2, and the length b becomes longer by δ · sin θ.

  However, among these, the portion of the length b from the corrugated valley bottom 10B to the next peak crest 10A on the rear end side has a twist angle of the cutting edge 10 with respect to the axis O as shown in FIG. When the length b of the weakly twisted cutting edge 10 in the direction of the axis O is increased, the cutting resistance is increased. That is, on the contrary, in the portion of the length a where the twist angle is larger than the twist angle θ, the cutting edge 10 is gradually cut into the work material from the peak portion 10A toward the valley bottom portion 10B. On the other hand, in the portion of the length b, the cutting edge 10 bites into the work material at a stroke, and if the length of the portion in the direction of the axis O is long, the load acting on the cutting blade 10 is also increased. It will be big.

  The present invention has been made under such a background, and in a roughing end mill having a cutting edge (outer peripheral edge) that is undulated as described above, the load acting on the outer peripheral edge is reduced and the cutting resistance is increased. The object is to provide a luffing end mill capable of suppressing the above.

  In order to solve the above-mentioned problems and achieve such an object, the present invention provides an end mill rotation direction on the outer periphery of the end portion of the end mill body rotated about the axis line from the front end of the end mill body toward the rear end side. A chip discharge groove that twists to the rear side is formed, and a wall surface facing the end mill rotation direction of the chip discharge groove is defined as a rake face, and a ridge portion on the outer peripheral side of the rake face is directed in a direction in which the chip discharge groove is twisted. A roughing end mill in which an outer peripheral blade that forms a waveform while twisting and is uneven in the direction of rotation of the end mill is formed, and the waveform formed by the outer peripheral blade is a length along the twist direction of the outer peripheral blade. The length from the peak of the convex part to the bottom of the valley where the waveform on the rear end side in the axial direction is concave is the length from the bottom of the valley to the bottom of the valley in the axial direction. Part to become Wherein the of being longer than the length up to the summit portion.

  In the luffing end mill configured in this way, the length from the peak of the corrugation to the bottom of the rear end on the length along the twist direction of the outer peripheral blade is the next from the bottom to the rear end. Since it is made longer than the length up to the peak, the length in the axial direction of the weakly twisted portion as described above is smaller than that of a roughing end mill in which these lengths are equal as in Patent Document 1. On the contrary, the length in the axial direction of the portion that is short and strongly twisted can be increased. For this reason, while reducing the load caused by the weakly twisted portion biting the work material at a stretch, the outer peripheral blade can be gradually cut as much as possible in the long strong twisted portion, Cutting resistance can be suppressed.

  However, even if the weakly twisted portion is shortened and the strongly twisted portion is lengthened in this way, if the strongly twisted portion is too long, the twist angle of the strongly twisted portion is close to the twist angle of the waveform reference line. As a result, the effect of making the outer peripheral blade uneven is impaired, and the weakly twisted portion extends from the bottom of the valley to the next peak so that the waveform becomes steep and convex, which may reduce the cutting edge strength. There is. Therefore, in the length along the torsional direction of the outer peripheral blade, the length from the top of the portion where the waveform is convex to the bottom of the valley where the waveform is concave on the rear end side in the axial direction. Is preferably 1.3 times or less the length from the bottom of the valley to the peak of the portion where the corrugation on the rear end side in the axial direction becomes the next convex.

  In particular, in the length along the axial direction, the corrugation formed by the outer peripheral blade, the bottom of the valley where the corrugation is concave on the rear end side in the axial direction from the peak of the convex portion of the corrugation Is approximately equal to the length from the bottom of the valley to the peak of the portion where the waveform on the rear end side in the axial direction is the next convex, the load and cutting resistance acting on these portions The cutting force and load acting on one wavelength of the outer peripheral blade can be effectively reduced. However, even though these lengths are not strictly equal, it is only necessary to match within a range of about 5% of one wavelength along the axial direction of the waveform.

  As described above, according to the present invention, it is possible to reduce the load caused by the weakly twisted portion on the outer peripheral edge that is wavyly concave and convex, and to suppress the cutting resistance by the strongly twisted portion. It is possible to smoothly perform the intermediate finishing of the cutting material.

It is a side view which shows one Embodiment of this invention. It is an expanded view explaining the waveform shape of the outer periphery blade in embodiment shown in FIG. It is an expanded view explaining the waveform shape of the cutting edge (outer peripheral blade) of the conventional luffing end mill.

  In the luffing end mill of the present embodiment, the end mill body 1 is integrally formed in a substantially cylindrical shape centering on the axis O with a hard material such as cemented carbide, and the rear end side (right side in FIG. 1) is the end mill body. 1 is a shank portion 2 for mounting on a spindle of a machine tool, and a tip end side (left side in FIG. 1) is a cutting edge portion 3, and an end mill rotating direction indicated by a symbol T around an axis O by the machine tool. The workpiece is cut by the cutting blade portion 3 by being fed out while being rotated.

  On the outer periphery of the cutting blade portion 3, there are a plurality of (four in this embodiment) chip discharge grooves 4 that are twisted to the rear side in the end mill rotation direction T around the axis O from the front end toward the rear end. It is formed at equal intervals in the circumferential direction. And the cross ridgeline part of the wall surface which faces the end mill rotation direction T side of these chip discharge grooves 4 and the outer peripheral surface (outer peripheral flank surface) of the cutting edge part 3 connected to the end mill rotation direction T rear side, that is, the above wall surface An outer peripheral edge 6 having this wall surface as an outer peripheral edge rake face 5 is formed on the outer peripheral side ridge portion, as in the case of the chip discharge groove 4, toward the rear side in the end mill rotation direction T around the axis O as a whole. It is formed to be twisted.

  In addition, a gash 7 is formed so that the inner peripheral side of the tip side opening of each chip discharge groove 4 is shaved and widened at the tip of the cutting edge 3, that is, the most distal end of the end mill body 1. A wall surface facing the end mill rotation direction T side of the gasche 7 is a bottom edge rake surface 8. Further, at the tip side ridge portion of the wall surface facing the end mill rotation direction T side of the chip discharge groove 4 including the bottom blade rake face 8, the axis line extends from the tip of the outer peripheral blade 6 toward the axis O in the radial direction. A bottom blade 9 extending to the vicinity of O is formed.

  Here, as shown in FIG. 2, the outer peripheral edge 6 has a constant twist angle θ with respect to the axis O, and a reference line L that twists toward the rear side in the end mill rotation direction T toward the rear end side in the axis O direction. Thus, the corrugations are uneven with a width equal to the front side and the rear side in the end mill rotation direction T. However, the rotation trajectory of the outer peripheral blade 6 around the axis O is formed in a cylindrical shape centered on the axis O, that is, the outer diameter of the outer peripheral blade 6 is constant.

  Accordingly, the actual twist angle of the outer peripheral blade 6 is gradually increased from the peak portion 6A of the undulating convex portion of the corrugated shape formed by the outer peripheral blade 6 toward the rear end side in the axis O direction with the constant twist angle θ as a reference. It becomes the maximum at the intermediate portion 6a between the peak portion 6A and the valley bottom portion 6B of the concave and convex portions. Further, the torsion angle of the outer peripheral blade 6 gradually decreases from the intermediate portion 6a toward the valley bottom portion 6B of the concave portion on the rear end side in the axis O direction (the rear side in the end mill rotation direction T). It becomes a constant twist angle θ. That is, from the peak portion 6A toward the rear end side, between the intermediate portion 6a and the valley bottom portion 6B, the torsion angle of the outer peripheral blade 6 is equal to or greater than a certain twist angle θ formed by the reference line. It becomes a twisted part.

  Next, as it goes to the rear end side in the axis O direction beyond the valley bottom 6B, the torsion angle of the outer peripheral blade 6 becomes smaller than the constant torsion angle θ, and the valley bottom 6B and the next uneven projection The intermediate portion 6b with the summit portion 6A is minimum. Further, the twist angle gradually increases from the intermediate portion 6b toward the rear end side, and the constant twist angle θ is again reached at the next peak portion 6A, and this is repeated. These intermediate portions 6a and 6b are strictly located between the peak portion 6A and the valley bottom portion 6B in the reference line L direction or the axis O direction, or between the valley bottom portion 6B and the next peak portion 6A. It does not have to be located.

  Accordingly, the twist angle of the outer peripheral blade 6 is not more than the constant twist angle θ from the valley bottom 6B toward the rear end side in the axis O direction (rear side in the end mill rotation direction T) up to the next peak portion 6A. It becomes a part of weak twist. In addition, in these peak part 6A and valley bottom part 6B, the twist angle of the outer periphery blade 6 is equal to the fixed twist angle (theta) used as the said reference | standard. Moreover, the waveform which this outer periphery blade 6 makes | forms has comprised the smooth uneven | corrugated curve shape in this embodiment.

  In the roughing end mill having the above-described configuration, the corrugated outer peripheral blade 6 has a waveform along the twist direction of the outer peripheral blade 6, that is, the length along the reference line L direction as shown in FIG. , The length A from the peak 6A to the valley bottom 6B on the rear end side in the axis O direction is longer than the length B from the valley bottom 6B to the peak 6A on the rear end side in the axis O direction. ing. That is, in the direction along the reference line L, the length A of the strong twist portion is longer than the length B of the weak twist portion.

  However, in the present embodiment, the lengths A and B of the strong and weakly twisted portions are the length A of the strongly twisted portion from the peak portion 6A to the valley bottom portion 6B on the rear end side in the axis O direction. The length B is 1.3 times or less the length B of the weakly twisted portion from 6B to the next peak portion 6A on the rear end side in the axis O direction. Further, particularly in the present embodiment, the waveform formed by the outer peripheral blade 6 is a strong twist portion from the peak 6A to the valley bottom 6B on the rear end side in the axis O direction in the length along the axis O direction. And the length b of the weakly twisted portion from the valley bottom portion 6B to the next peak portion 6A on the rear end side in the axis O direction are made substantially equal to each other.

  In addition, although the corrugated shape and twist angle of each outer peripheral blade 6 and the twist angle and the change thereof, and the lengths A and B are different, the outer peripheral blades 6 adjacent to each other in the circumferential direction, The phase of the waveform shape formed by both outer peripheral blades 6 is shifted in the direction of the axis O. That is, the peak part 6A, the valley bottom part 6B, and the intermediate parts 6a and 6b are shifted in the direction of the axis O between the adjacent outer peripheral blades 6 with the same interval therebetween.

  For example, in the present embodiment in which the four outer peripheral blades 6 are formed at equal intervals in the circumferential direction, the phases of the outer peripheral blades 6 positioned on opposite sides of the axis O are matched and adjacent in the circumferential direction. In the peripheral blades 6, a crest portion 6 </ b> A of one outer peripheral blade 6 and a valley bottom portion 6 </ b> B of the other outer peripheral blade 6, and a valley bottom portion 6 </ b> B of one outer peripheral blade 6 and a crest portion 6 </ b> A of the other outer peripheral blade 6. The positions in the direction of the axis O may be the same, and the positions of the peak portions 6A, the valley bottom portions 6B, and the intermediate portions 6a and 6b of the outer peripheral blades 6 are the same in the direction of the axis O. Thus, the phase of all the outer peripheral blades 6 may be shifted.

  In the luffing end mill configured as described above, not only a good chip disposal property is ensured by the outer peripheral blade 6 that is wavyly uneven, but the length in the reference line L direction along the twist of the outer peripheral blade 6 as described above. , The length A of the strongly twisted portion from the corrugated peak 6A to the valley bottom 6B on the rear end side is the length B of the weak twist from the valley bottom 6B to the next peak 6A on the rear end. In particular, the resistance caused by the weakly twisted portion biting the work material can be suppressed. On the other hand, since the outer peripheral blade 6 can be gradually cut into the work material as much as possible by the strongly twisted portion having the length A increased, the sharpness of the outer peripheral blade 6 as a whole is improved. The cutting resistance can be suppressed, and these make it possible to smoothly perform the intermediate finishing of the work material.

  Further, in this embodiment, the length A along the reference line L of the portion to be strongly twisted from the peak 6A to the valley bottom 6B on the rear end side in the axis O direction is the length A along the axis O from the valley bottom 6B. Even if it is longer than the length B of the weakly twisted portion up to the next peak portion 6A on the rear end side, the length A is 1.3 times or less than the length B. Further, it can be prevented that the weakly twisted portion becomes too short and the rising edge from the valley bottom portion 6B to the next peak portion 6A becomes too steep to impair the cutting edge strength. On the other hand, even in a portion that is strongly twisted, it is possible to prevent the sharpness from being lost due to the twist angle becoming gentle and close to the twist angle of the reference line L.

  Moreover, particularly in the present embodiment, the lengths A and B along the reference line L, which is the direction of twisting of the outer peripheral blade 6, satisfy A> B, whereas the strong twist along the axis O direction. The length a of the portion a and the length b of the weakly twisted portion are a≈b and are substantially equal. Therefore, this effectively balances the resistance and load acting on the strongly twisted portion and the weakly twisted portion in the direction of the axis O, so that the load and cutting resistance acting on the outer peripheral edge 6 for one wavelength are effectively obtained. It becomes possible to reduce it.

  However, even in such a case, even if the lengths a and b of the strong / weak twist portions in the axis O direction are not strictly equal, for example, the length of one wavelength along the axis O direction of the waveform It suffices if the values match within a range of about 5% or less with respect to a + b. In order to make the length a equal to the length b, the twist angle θ of the reference line L and the depth (waveform) from the peak 6A to the valley bottom 6B in the direction perpendicular to the reference line L of the waveform. The length A of the strongly twisted portion along the reference line L may be made longer by 2 · δ tan θ than the length B of the weakly twisted portion.

DESCRIPTION OF SYMBOLS 1 End mill main body 3 Cutting edge part 4 Chip discharge groove 5 Peripheral blade rake face 6 Peripheral blade 6A Corrugated peak part which outer peripheral blade 6 makes 6B Corrugated valley bottom part which outer peripheral blade 6 makes 9 Bottom edge O End mill main body 1 axis T End mill Rotational direction L Reference line of the outer peripheral blade 6 forming a waveform θ Torsion angle of the reference line L of the outer peripheral blade 6 A Torsion of the outer peripheral blade 6 from the peak 6A toward the rear end side in the axis O direction to the valley bottom 6B (reference line) L) Length along B B Length along the twist (reference line L) of the outer peripheral blade 6 from the valley bottom 6B toward the rear peak side in the direction of the axis O to the next peak crest 6A a From the peak 6A to the axis O Length along the axis O direction from the valley bottom 6B toward the rear end side in the direction b Length along the axis O direction from the valley bottom 6B toward the rear end side in the axis O direction to the next peak 6A

Claims (3)

  A chip discharge groove that twists toward the rear side in the end mill rotation direction from the front end of the end mill body toward the rear end side is formed on the outer periphery of the end portion of the end mill main body rotated about the axis. A roughing end mill having a facing wall as a rake face, and an outer peripheral edge that is undulated in the direction of rotation of the end mill by forming a waveform while twisting toward the direction in which the chip discharge groove is twisted at the ridge on the outer peripheral side of the rake face The corrugation formed by the outer peripheral blade has a length along the twist direction of the outer peripheral blade, and the corrugation on the rear end side in the axial direction from the peak of the convex portion of the corrugation is concave. The length from the bottom of this portion to the bottom of the valley is longer than the length from the bottom of the valley to the top of the top of the portion where the waveform on the rear end side in the axial direction becomes convex. Grayed end mill.   In the length along the torsional direction of the outer peripheral blade, the length from the peak of the portion where the waveform is convex to the bottom of the valley where the waveform is concave on the rear end side in the axial direction is 2. A length of 1.3 times or less of the length from the bottom of the valley to the peak of the next convex portion of the waveform on the rear end side in the axial direction. Roughing end mill as described in.   In the length along the axial direction, the waveform formed by the outer peripheral blade extends from the peak of the portion where the waveform is convex to the bottom of the valley where the waveform is concave on the rear end side in the axial direction. 2. The roughing end mill according to claim 1, wherein the length is substantially equal to the length from the bottom of the valley to the top of the peak where the waveform on the rear end side in the axial direction is the next convex. .

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