JP2010240818A - End mill with chip breaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an end mill with a chip breaker capable of efficiently machining at a high speed without causing an accident such as a breakage in a chip breaker part, while securing excellent cut surface accuracy. <P>SOLUTION: The end mill has a plurality of peripheral blades, and a plurality of chip breakers for cutting chips from a tool tip side to a tool shank side, arranged with an interval in the periphery of a tool body to be rotated around the axis. With a view of the chip breaker and the peripheral blade in a cross sectional surface parallel with a torsion angle of the end mill, both ends of respective chip breaker, which are formed roundish, are smoothly continued to the peripheral blade adjacent to the chip breaker, and a radius of the roundness of the chip breaker on the tool tip side is smaller than the radius of the roundness of the chip breaker on the tool shank side, and a bottom end of a chip breaker groove is connected to the tool shank side roundness by a straight line or in a curved line projecting toward the chip breaker groove, or continued in combination of the straight line and the curved line projecting toward the chip breaker groove. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a nicked end mill.

  In an end mill with multiple outer peripheral edges, by providing a nick that divides the chips from the tool tip side to the tool shank side on the outer peripheral edge, the resistance during cutting is reduced and the chip disposal is good. It is known that high cutting can be performed. Further, there is also known a tool that can realize a machined surface roughness of a medium finishing level by a flat outer peripheral blade portion when sandwiched between nicks. The end mill described in Patent Documents 1 and 2 is an example. Patent Document 1 describes an end mill that attempts to secure the strength of a portion where a nick and an outer peripheral blade portion are connected by providing a large flank angle at both ends of the nick. An end mill that improves chipping resistance and machined surface roughness by rounding each connecting portion is described.

Japanese Patent Laid-Open No. 06-335814 JP 2005-131728 A

  However, as a result of detailed studies by the inventor for the purpose of achieving both an excellent semifinished surface and cutting efficiency, the optimization of the shape on both sides of the nick and the nick groove shape plays a very important role. Became clear. The shape of the nick described in Patent Document 1 has a sharp edge shape as shown in FIG. Although it is intended to secure strength by providing large flank angles at both ends of the nick, in high-efficiency machining, there is a big problem from chipping resistance. Therefore, highly efficient processing is difficult.

  In the tool described in Patent Document 2, the chipping resistance can be improved by providing rounds on both sides of the nick, but the round radius on the nick tool tip side is relatively larger than the round radius on the tool shank side. In addition, the sharpness is poor, and it tends to lead to deterioration of the processed surface roughness and generation of streaks on the processed surface. Further, as shown in FIG. 5, the nick placed in the direction perpendicular to the axis of the tool has an acute angle on the shank side of the tool, so that the strength of the nick tool shank side is weaker than the nick tool tip side. Since the nick groove shape described in Patent Document 2 is a concave arc shape as shown in FIG. 9, there is an angled portion at the boundary between the nick tool shank side and the tool tip side round connection portion. Since chipping is likely to occur when machining under high-efficiency conditions with high feed, the tool has a short cutting life and the accuracy of the machined surface deteriorates.

  The present invention has been made based on the background as described above, and is an end mill capable of performing from roughing to intermediate finishing, while maintaining good intermediate finishing surface roughness. The purpose is to provide an end mill with a nick that can achieve a machining efficiency more than double.

  In order to achieve such an object, the present inventor examined the optimum nick shape by changing the shape of the nick and repeatedly evaluating the cutting test. As a result, it was found that changing the shape of the portion where the nick is connected to the outer peripheral blade and changing the shape connecting the nick connecting portion and the bottom of the nick groove are important for solving the above problem.

  That is, among the present inventions, the first invention is an end mill in which a plurality of nicks are provided on the outer periphery of a rotary tool main body having a plurality of outer peripheral blades at intervals to sever chips from the tool tip side toward the shank side. When the nick and the outer peripheral edge are viewed on a cutting plane parallel to the torsion angle of the end mill, both ends of each nick are smoothly connected to the outer peripheral edge adjacent to the nick due to roundness. The round radius on the tool tip side is smaller than the round radius on the tool shank side of the nick, and the bottom of the nick groove is connected to the round on the tool shank side or a convex curve toward the nick groove, or the straight line and the It is an end mill with a nick characterized by connecting with a convex curve toward a nick groove.

  According to a second invention of the present invention, in the end mill with a nick according to the first invention, when the tool diameter of the end mill is D, the round radius R1 on the tool tip side of the nick is 0.01D to 0.03D. The round radius R2 on the tool shank side is 1.5 to 2 times the round radius on the tool tip side of the nick, and the nick depth is 0.01D to 0.05D.

Since the nicked end mill of the present invention is provided with the round radius R1 on the tip end side of the nick that is smaller than the round radius R2 on the nick tool shank side, the sharpness is improved and the streaks on the machining surface can be reduced. A highly accurate machined surface can be realized.
According to the present invention, as with a luffing tool having a corrugated blade outer peripheral edge, it is possible to cut chips finely, to perform cutting with low resistance and high efficiency, and as an effect superior to the luffing tool, rough cutting Even when compared with conventional end mills with nicks at the stage, the machined surface roughness is improved even when cutting at twice the efficiency.
If the end mill with a nick according to the present invention is used, intermediate finishing and finishing are not necessarily required, and cutting is completed in one step from rough finishing, contributing to a significant reduction in processing time and reduction in tool costs. .
The nicked end mill of the present invention does not need to worry about chipping and other defects due to the new nick shape, so that it is possible to perform cutting with higher efficiency.

  If the end mill with a nick according to the present invention is configured as in the second invention, a highly efficient machining and a highly accurate machining surface can be ensured more reliably. In addition, even under machining conditions with a large single-blade feed amount, chips are divided well, cutting resistance is reduced, and cutting performance is improved.

It is a general-view figure of the end mill with a nick which is one Example of this invention. It is AA 'sectional view which looked at the nick of FIG. 1 and an outer periphery blade in the cut surface parallel to the twist angle of an end mill, and is the figure which made the connection of the roundness of the bottom end of a nick groove and the tool shank side straight. is there. In FIG. 2, it is the figure which made the convex curve toward the nick groove the connection of the bottom end of a nick groove and the roundness by the side of a tool shank which is another example of this invention. In FIG. 2, it is the figure which made the combination of the convex curve and a straight line toward the nick groove the connection of the bottom end of a nick groove and the roundness by the side of a tool shank which is another example of this invention. It is explanatory drawing of the acute angle and obtuse angle of the corner where a nick and an outer periphery blade cross | intersect with respect to the rotating shaft of an end mill. FIG. 3 is a view corresponding to a cross-sectional view taken along the line AA ′ of FIG. 2 for a conventional end mill with a nick in which the bottom end of the nick groove and the roundness on the tool shank side have a concave curve toward the nick groove. It is a figure showing the nick | nick shape described in patent document 1 which is an edge shape with a sharp connection of a nick and an outer peripheral blade part. In the nick shape of FIG. 7, it is a figure showing the nick shape described in patent document 1 which provided roundness to this nick shape. The connection between the nick and the outer peripheral blade portion is a roundness smaller than the radius of the concave arc shape forming the nick groove, and the size of the roundness is described in Patent Document 2 in which the tool tip side and the tool shank side are the same. It is a figure showing a nick shape. FIG. 10 is a diagram illustrating the nick shape described in Patent Literature 2 in which the roundness radius of the tool shank side is larger than the round radius of the tool tip side in the nick shape of FIG. 9.

  As a typical embodiment of the present invention, a nicked end mill of the present invention will be described with reference to FIGS. FIG. 1 is an overview of a nicked end mill according to an embodiment of the present invention. As shown in FIG. 1, the end mill of the present invention has a plurality of outer peripheral blades 1 with a tool diameter D, and on the outer periphery of an end mill body having a plurality of outer peripheral blades 1 from the tool tip side 2 toward the shank side 3. Nicks 4 for dividing the chips are arranged at predetermined intervals.

  The detailed shape of the nick 4 of the present invention will be described with reference to FIG. FIG. 2 is a view showing the AA ′ cross section of FIG. 1, and is a view in which the connection between the bottom end 8 of the nick groove and the round 6 on the tool shank side is a straight line. Since the end mill has a predetermined twist angle θ, the AA ′ cross section is a cross section obtained by viewing the nick and the outer peripheral edge with a cut surface parallel to the twist angle of the end mill. In the description of FIGS. 2 to 4, 6, and 9 to 10, for convenience, the radius of the arc (roundness) existing on the shank side and the tool tip side of a nick tool is set to the roundness 5 on the tool tip side. Is referred to as a round radius R1 on the tool tip side, and a round radius 6 on the tool shank side is referred to as a round radius R2 on the tool shank side. In the nicked end mill of the present invention, the nick 4 has a round 5 on the tool tip side partially having an arc with a round radius R1 on the tool tip side, and a tool shank side having a partial arc with a round radius R2 on the tool shank side. The outer peripheral blade 1 and the nick groove 9 are connected by the roundness 6. The round radius R1 on the tool tip side of the nick 4 is smaller than the round radius R2 on the tool shank side of the nick. Further, the bottom portion 7 of the nick groove 9 of the nick groove 9 has a concave shape, and is connected to the round radius R2 on the tool shank side at the bottom end 8 of the nick groove with a straight or convex curve.

  In the end mill with a nick of the present invention, there are three types of connection methods in the cross-sectional shape of the bottom end 8 of the nick groove and the round 6 on the tool shank side, and such states are shown in FIGS. FIG. 2 which has already been representatively described is an example in which the connection between the bottom end 8 of the nick groove and the roundness 6 on the tool shank side is a straight line 10. FIG. 3 is an example in which the connection between the bottom end 8 of the nick groove and the round 6 on the tool shank side is connected to the nick groove 9 by a convex curve 11. FIG. 4 is an example in which the connection between the bottom end 8 of the nick groove and the round 6 on the tool shank side is connected by a combination of a convex curve 11 and a straight line 10 toward the nick groove 9. 2 to 6 indicate the cross section of the end mill.

  FIG. 5 is an explanatory diagram of the acute angle 12 and the obtuse angle 13 at the corner where the nick 4 and the outer peripheral blade 1 intersect with the rotation axis. In the end mill with a nick according to the present invention, as shown in FIG. 5, the tool tip side 2 and the tool shank side 3 are compared with each other. Since the intersecting corner has an acute angle 12, the shape is weaker than the obtuse angle 13 on the tool tip side 2.

  Further, like the conventional end mill with a nick shown in FIG. 6, the shape of the contour forming the nick groove is a concave arc shape, that is, the bottom 9 of the nick is a concave curve toward the round 6 on the tool shank side and the nick groove. In particular, the nicked shape on the tool shank side 3 is recessed on the tool side, and the boundary connected by the rounded shape on the tool shank side and the concave arc-shaped curve 14 is conspicuous. Since there is a portion and chipping is likely to occur when machining under high-efficiency conditions with high feed, the cutting life of the tool is shortened and the accuracy of the machined surface is deteriorated. On the other hand, in the nick shape of the present invention, as illustrated in FIGS. 2 to 4, the connection between the round 6 on the tool shank side and the bottom end 8 of the nick groove is convex toward the straight line 10 or the nick groove. By connecting with the curved line 11 or the combination of the convex curve 11 and the straight line 10, the strength can be increased, and even when cutting under high-efficiency machining conditions with high feed, stable chipping does not occur Can be processed. As described above, in the present invention, how to connect the bottom end 8 of the nick groove and the round 6 on the side of the tool shank in the cross-sectional shape is one of the most important elements of the invention and greatly affects the cutting characteristics. Revealed. Focusing on the detailed part of the nick shape of the end mill and evaluating the cutting characteristics while evaluating the cutting characteristics, there is no prior art.

  In the nicked end mill of the present invention, it is desirable that the round radius R1 on the tool tip side of the nick 4 is within a range of 0.01D to 0.03D (D represents a tool diameter). This is because within this range, the strength of the tool tip side 2 connected to the nick 4 and the outer peripheral blade 1 can be more sufficiently secured, and chipping can be prevented. If the roundness radius R1 on the tool tip side is less than 0.01D, the strength is relatively weak, and chipping may occur when cutting. When the roundness radius R1 on the tool tip side exceeds 0.03D, the force that presses the machining surface toward the tool shank increases, and as a result, it becomes easy to leave a streak on the machining surface and affects the machining surface accuracy.

  Further, the round radius R2 on the tool shank side of the nick 4 of the nicked end mill of the present invention is preferably in the range of 1.5 to 2 times the tool diameter D. Thereby, the nick 4 and the outer peripheral blade 1 are connected well, and the strength of the tool shank side 3 of the nick groove 9 can be sufficiently secured to prevent chipping, so that high-efficiency machining with high feed can be performed. If the round radius R2 on the tool shank side of Nick 4 is less than 1.5 times the tool diameter D, the strength is insufficient. When the round radius R2 on the tool shank side of the nick 4 exceeds twice the tool diameter D, the cutting resistance increases, so that any chipping tends to occur.

The nick depth H of the nicked end mill of the present invention is preferably within a range of 0.01D to 0.05D. When the nick depth H is less than 0.01D, a single blade feed amount cannot be increased. In that case, it is difficult for the nick 4 to work effectively. For example, when the single blade feed amount is larger than the nick depth H, chips are connected and high feed becomes difficult. On the other hand, when the single blade feed amount is smaller than the nick depth H, high feed cannot be performed. On the other hand, when the nick depth H exceeds 0.05D, the strength of the cutting edge becomes weak and chipping may occur.
By the nick depth H in this range, the chips are more favorably divided, the cutting resistance is reduced, and high-efficiency machining is further ensured.

  2 to 4, three nick groove contours are representatively shown. However, in the present invention, the radius R1 on the tool tip side is the radius on the tool shank side in any nick 4. Although smaller than R2 is an essential condition, the values of the round radius R1 on the tool tip side and the round radius R2 on the tool shank side for each nick 4 need not be the same for all nicks 4. However, since it is usual to use a grindstone in the grinding process when forming the nick groove 9, it is convenient to grind with the same grindstone shape in the manufacture of the end mill with nick, and therefore it can be said that substantially the same dimensions are desirable.

  Both Patent Document 1 and Patent Document 2 are inventions characterized by a nick shape, but the conventional examples 1 to 4 manufactured and evaluated based on the shape of these inventions are columns of effects described in Table 1 of the Examples. As can be seen from the above, it has been clarified that each has the following problems.

  The shape of the nick described in Patent Document 1 has a sharp edge shape such that the shape in which the nick 4 and the outer peripheral blade portion 1 are connected is illustrated in FIG. Although it is intended to secure strength by providing large flank angles at both ends of the nick, in high-efficiency machining, there is a big problem from chipping resistance. In particular, when cutting under high-efficiency conditions, if the edge portion 15 is sharp with a sharp edge as shown in FIG. 7, the possibility of chipping is high, leaving streaks on the processed surface. As a result, there is a problem that sufficient processed surface roughness cannot be obtained. In addition, Patent Document 1 has a description that the sharp edge may be rounded (R), but it is only an idea that rounding may be done in a common sense range, and the basic shape is It remains in the shape of FIG. 7 and 8 indicate cross sections of the end mill.

  As the purpose of the present invention, it is important in an end mill with a nick for achieving a machining efficiency (single blade feed amount, rotation speed) more than twice that of the conventional product while maintaining the surface finish of the intermediate finish. That is, it is not enough to just round the common sense, and the shape where the nick 4 and the outer peripheral blade 1 are connected, including the relationship between the roundness of the tool tip side 2 and the tool shank side 3, is considered. Thus, how to connect with the nick groove 9 is important. The nicked end mill of the present invention has an optimum size of the round radius R1 on the tool tip side and the round radius R2 on the tool shank side, and the mutual relationship between the round radius R1 on the tool tip side and the round radius R2 on the tool shank side. As a result of investigating the relationship between the nick groove bottom 7 and the nick shank side roundness 6, the sharpness to obtain the roughness of the finished surface that could not be achieved with the conventional shape was ensured. In addition, it has succeeded in achieving a compatible effect that is optimal for Nick's chipping resistance.

  The shape of the nick described in Patent Document 2 corresponds to a round radius R1 on the tool tip side and a round radius R2 on the tool shank side of the present invention as shown in FIG. 9 as a shape connecting the nick and the outer peripheral blade portion. It is a shape that coincides with the point that the portion is arcuate. However, as in the present invention, what is the round radius R1 on the tool tip side and the round radius R2 on the tool shank side, and the mutual sizes of the round radius R1 on the tool tip side and the round radius R2 on the tool shank side are There is no recognition of the relationship, and the recognition is limited to an arc smaller than the radius of the concave arc shape forming the nick groove. Further, the decisive difference from the present invention is that the nick described in Patent Document 2 requires a large concave arc shape (radius R3 in FIGS. 9 and 10). According to the evaluation of the present inventor, the concave arc shape has a nick shape on the tool shank side 3 that is indented or angled on the tool side. Unbearable in strength. This is also clear from the results of Examples (Table 1) of Conventional Examples 3 and 4 in which a cutting test was performed with an end mill having a nick shape described in Patent Document 2. In addition, the oblique line of FIG. 9, FIG. 10 shows the cross section of an end mill.

  The nicked end mill of the present invention is connected continuously from the roundness on the tool shank side to the bottom end of the nick groove by a straight line or a convex curve toward the nick groove, or by a combination of the straight line and the convex curve. ing. The strength of the nick due to this shape is significantly higher than the nick shape described in Patent Document 2 in which a concave arc-shaped recess is provided toward the nick groove.

  The desirable shape of the nick 4 of the present invention that can be understood from the embodiment of the present invention and the partial role of the shape are summarized as follows. The roundness radius R1 on the tool tip side is particularly necessary for ensuring sharpness and maintaining the surface roughness after securing the strength, and the range is 0.01D to 0.00 when the tool diameter is D. 05D is desirable. A more desirable range is 0.01D to 0.03D. The round radius R2 on the tool shank side is preferably 1.1 to 2.5 times the round radius R1 on the tool tip side, mainly for the purpose of ensuring the chipping resistance of the nick 4. A more desirable range of the round radius R2 on the tool shank side is 1.5 to 2.0 times the round radius R1 on the tool tip side. However, the effects of the round radius R1 on the tool tip side and the round radius R2 on the tool shank side described here are not exhibited independently, but are satisfied when the overall requirements for the nick shape are satisfied.

An object of the present invention is to provide an end mill with a nick that can maintain a surface roughness of a semi-finished surface and can realize a machining efficiency (single blade feed amount, rotation speed) that is twice or more that of a conventional product. As a result of studying various nick shapes in a nicked end mill to achieve this, the nick shape is a slight difference in the nick strength and sharpness (the sharpness also affects the surface roughness of the workpiece), and chips. It has been found that this has an effect on the fragmentation and chip discharge. As a result of examining the shape of the nick including the conventional example in the embodiment of the present invention, in particular, the shape from the nick groove to the outer peripheral blade and the shape connecting the nick and the outer peripheral blade are large to achieve the object of the present invention. I found out there was an effect.
Hereinafter, the present invention will be described in detail with reference to the following examples, but the present invention is not limited thereto.

Example 1
End mill shape conditions common to the present invention example, comparative example, and conventional example are a square end mill, a blade diameter of 10 mm, a core thickness of 6.5 mm, a peripheral rake angle of 0 degree, a helix angle of 43 degrees, and a number of blades of 4 A sheet was prepared with Nicks arranged in a staggered pattern on the outer peripheral blade. The radius radius R1 on the tool tip side of the nick of the square end mill, the radius radius R2 on the nick tool shank side, the nick depth being changed, and the shape connecting the bottom end of the nick nick groove and the roundness on the tool shank side As a comparative example of the present invention, the round shape radius R1 on the tool tip side and the radius on the tool shank side based on the shape described in Patent Document 1 and Patent Document 2 and the description in Patent Document 1 described above What gave R2 and what made round radius R2 by the side of a tool shank larger than round radius R1 by the side of a tool tip of the above-mentioned patent documents 2 were produced as a conventional example.

  Table 1 shows the serial number for each of the present invention example, comparative example, and conventional example. Among the present invention examples 1, 2, and 3, the nick radius R1 on the tool tip side is 0.025D (actual size is 0). .25 mm, the same shall apply hereinafter), the radius R2 of the nick on the tool shank side is 1.6 times (0.4 mm) of the radius R1, the nick depth is 0.03 times (0.3 mm) of D, and the nick groove The shape connecting the bottom end and the roundness on the tool shank side is changed. Inventive Examples 4 and 5 were prepared with the same specifications as in Inventive Example 1 except that the round radius R2 on the tool shank side was 1.6 times the radius R1, and the round radius R1 on the tool tip side was not. In Invention Example 4, the round radius R1 on the tool tip side is 0.01D (0.1 mm), and in Invention Example 5, the round radius R1 on the tool tip side is 0.03D (0.3 mm). Invention Examples 6 and 7 were prepared with the same specifications as in Invention Example 1 except for the round radius R2 on the tool shank side. In the present invention 6, the round radius R2 on the tool shank side is 1.5 times the radius R1, and in the inventive example 7, the round radius R2 on the tool shank side is 2.0 times the radius R1. Examples 8 and 9 of the present invention were prepared with the same specifications as Example 1 of the present invention except for the nick depth, and Example 8 of the present invention had a nick depth of 0.01 times (0.1 mm) D, and Example 9 of the present invention. The nick depth was 0.05 times D (0.5 mm).

  Examples 10 to 15 of the present invention exemplify examples in the range around claim 2 of the present invention showing the optimum range of the nick shape of the present invention. Among them, Examples 10 and 11 of the present invention investigated the influence of R1 by setting the round radius R2 on the tool shank side to 1.6 times the radius R1. Except for the rounding radius R1 on the tool tip side, the same specifications as those of Example 1 were produced. In the inventive example 10, the round radius R1 on the tool tip side is 0.008D (0.08 mm), and in the inventive example 11, the round radius R1 on the tool tip side is 0.034D (0.34 mm). Invention Examples 12 and 13 were obtained by investigating the influence of the round radius R2 on the tool shank side. In the inventive example 12, the round radius R2 on the tool shank side is 1.3 times the radius R1, and in the inventive example 13, the round radius R2 on the tool shank side is 2.5 times the radius R1. Inventive Examples 14 and 15 were prepared with the same specifications as in Inventive Example 1 except for the nick depth, and the influence of the nick depth was examined. Among them, in Example 14 of the present invention, the nick depth was 0.008 times (0.08 mm) of D, and in Example 15 of the present invention, the nick depth was 0.07 times (0.7 mm) of D.

  Comparative Example 1 was produced with the same specifications as Example 1 except that the round radius R2 on the tool shank side was the same as the round radius R1 on the tool tip side and 0.025 times (0.25 mm) D. In Comparative Example 2, the round radius R1 on the tool tip side is 0.04 times (0.4 mm) of D, the round radius R2 on the tool shank side is 0.25 mm, and the radius is smaller than the round radius R1 on the tool tip side. The same specifications as those of Invention Example 1 were produced. Comparative Example 3 was produced with the same specifications as Example 1 of the present invention except that the connection between the bottom end of the nick groove and the roundness on the tool shank side was a concave arc-shaped curve toward the nick groove.

  Conventional Example 1 is a nick shape described in Patent Document 1 having an edge shape in which the connection between the nick and the outer peripheral blade is sharp, and the shape is shown in FIG. It was produced with the same specifications as Example 1 of the present invention except that the tool tip side and the tool shank side of Nick were not rounded.

  Conventional example 2 is the nick shape described in Patent Document 1 that the nick shape in FIG. 7 may be rounded, and the shape is shown in FIG. Conventional Example 1 except that the radius R1 on the tool tip side of Nick is set to 0.005 times (0.05 mm) of D and the radius R2 of the tool shank side is set to 1 time (0.05 mm) of radius R1. And the same specifications.

  In Conventional Example 3, the connection between the nick and the outer peripheral edge is a round smaller than the radius of the concave arc shape forming the nick groove, and the size of the round is the same on the tool tip side and the tool shank side. The described nick shape is shown in FIG. The connection between the nick and the outer peripheral edge is a concave arc, the round radius R1 on the nick tool tip side is 0.025 times (0.25 mm) of D, the round radius R2 on the tool shank side is the round radius R1 on the tool tip side It was produced as the same specification as Example 1 of the present invention except that it was provided in the same manner.

  Conventional Example 4 is the nick shape described in Patent Document 2 in the case where the radius of roundness on the shank side is larger than the radius of roundness on the tool tip side in the nick shape of FIG. 9, and the shape is shown in FIG. . The connection between the nick and the outer peripheral edge is a concave arc, the nick radius R1 on the tool tip side is 0.01 times (0.1 mm) of D, and the radius R2 on the tool shank side is 1.3 times the radius R1 ( 0.13 mm), and the same specifications as in Conventional Example 3 were prepared.

  Conventional example 5 has a conventional nicked end mill shape in which the connection between the bottom end of the nick groove and the roundness on the tool shank side is a concave arc curve toward the nick groove. It was produced with the same specifications as Example 1 of the present invention except that the tool tip side and the tool shank side of Nick were not rounded. Conventional Example 6 has a general shape of a conventional tool.

  In Table 1, the nick shape “straight link” is a straight line that connects the bottom end of the nick groove and the round radius R2 on the tool shank, and the “convex curve” is a curve that is convex toward the nick groove. The tool shank side round radius R2 is connected to the bottom end of the nick groove. “Line + convex curve” is a combination of a straight line and a convex curve toward the nick groove, and the round radius R2 on the tool shank side. Is connected to the bottom end of the nick groove, and the "concave arc" is a conventional example of connecting the round radius R2 on the nick tool shank side and the bottom end of the nick groove with a concave arc or concave curve. It is.

  The cutting test conditions were the same for all sample numbers. The work material is a block material of stainless steel SUS304. The rotation speed of the end mill is 4000 rpm / min (cutting speed 120 m / min), the axial depth of cut is 10 mm, and the radial depth of cut is 4 mm. used. In this type of conventional end mill, the average feed speed when the average surface roughness is ensured is around 500 mm / min. Therefore, in order to evaluate the machining efficiency of the present invention, the feed speed is 500 mm / min (single blade feed). The feed rate was gradually increased from the amount 0.03 mm / min) to find the limit of feed. Therefore, if the feed rate is 1000 mm / min) or higher and there is no problem of chipping or deterioration of the machined surface roughness, it can be said that the target of the machining efficiency is twice or more than the conventional one.

  As an evaluation standard, when a defect such as chipping occurs or when the average surface roughness Ra of the work surface of the work material reaches 4 μm or more, the cutting is stopped, and the feed rate at that time is set to the limit feed rate (mm / Min). When the limit feed rate was 1300 mm / min, there were no defects such as chipping, and the average processed surface roughness Ra of the processed surface was 4 μm or less, and indicated as “good” by ○. When the limit feed speed was 1600 mm / min, there were no problems such as chipping, and the average machined surface roughness Ra of the machined surface was 4 μm or less, which was indicated by “◎” as “high-speed feed good”. When the limit feed speed was 1300 mm / min or less and the chipping or average surface roughness Ra exceeded 4 μm, the average processed surface roughness Ra of the processed surface at that time was measured and marked with x. Table 1 shows the specifications and results of each sample.

  From Table 1, in all of inventive examples 1 to 15, when the limit feed speed was 1300 mm / min, there was no chipping or chipping, and high-feed machining was possible with an average surface roughness Ra of 4 μm or less. In particular, in Examples 1, 2, 3, 5, 6, 7, and 9 of the present invention, when the limit feed speed is 1600 mm / min, there is no defect such as chipping, and the average processed surface roughness Ra of the processed surface is 2 It was below 0.0μm, and a high-efficiency and high-accuracy machining surface with high feed could be secured.

  In Comparative Example 1, chipping occurred when the feed rate was 1000 mm / min. This means that the roundness on the tool tip side and the tool shank side of Nick is the same, and R2 is as small as 0.25 mm, so that the strength is insufficient. In Comparative Example 2, after cutting at a feed rate of 800 mm / min, streaks were left on the processed surface of the work material, and the average surface roughness Ra was 4.98 μm (over 4 μm). This is because the roundness at the tip of Nick's tool is larger than the roundness at the tool shank, so the force that presses the machining surface against the tool shank increases, leaving streaks on the machining surface and increasing the average surface roughness Ra. Indicates. In Comparative Example 3, the bottom of the nick groove is connected to the round shape on the shank side of the tool by a concave arc having a lower strength, and the strength is insufficient. Therefore, when machining at a feed rate of 900 mm / min, the nick tool shank Chipping occurred in the groove on the side.

  In Conventional Example 1, chipping occurred when processing at a feed rate of 600 mm / min, and the average surface roughness Ra was 4.94 μm. This indicates that the tip is not rounded on the tool tip side and the tool shank side of the nick, so that the strength is weak and chipping occurs in the high feed processing. Conventional Example 2 was a case where the nick shape of Conventional Example 1 was provided with roundness on the tool tip side and the tool shank side, and chipping occurred when machining at a feed rate of 700 mm / min. In Conventional Example 3, chipping occurred on the nick tool shank side when machining at a feed rate of 800 mm / min. This is because the round radius R2 on the tool shank side of Nick is the same as the round radius R1 at the tip of the tool, and the strength is weaker, and the connection between Nick and the outer peripheral blade becomes concave, resulting in further insufficient strength And indicates that chipping has occurred.

Conventional Example 4 is a case where the roundness on the tool shank side is larger than the roundness on the tool tip side of Nick in the nick shape of Conventional Example 3. When the feed rate was 700 mm / min, chipping occurred in the groove portion on the nick tool shank side, and the average surface roughness Ra was 5.23 μm. This indicates that the connection between the nick and the outer peripheral edge is concave, the strength is insufficient, and chipping occurs under high efficiency conditions.
In Conventional Example 5, chipping occurred when processing at a feed rate of 500 mm / min, and the processed surface roughness was 5.39 μm. This is because the nick tool tip side and tool shank side are not rounded, and the outer edge and the bottom end of the nick groove are connected by a concave arc, so the nick strength is weak and chipping occurs in high feed processing. Indicates.
In Conventional Example 6, when processed at a feed rate of 600 mm / min, the processed surface average surface roughness Ra was 5.33 μm. This indicates that the nicked tool tip side and the tool shank side are large in roundness and the resistance applied to the machining surface is large, so that streaks are generated on the machining surface and the surface roughness is deteriorated.

The nicked end mill of the present invention cuts the chips finely in the same way as a luffing tool with a corrugated peripheral blade by a combination of a characteristic nick shape and peripheral blade, and processes at a feed rate more than twice that of the conventional shape. It becomes possible to do. The nicked end mill of the present invention does not need to worry about chipping and other defects, and the surface finish is improved even if it is cut at a high feed rate in the rough cutting process stage, so intermediate finishing and finishing are always required This contributes to a significant reduction in machining time and tool costs.
The main workpiece to be cut of the nicked end mill of the present invention is, for example, mild steel, structural steel or stainless steel, and is particularly suitable for cutting of parts.

DESCRIPTION OF SYMBOLS 1 Perimeter blade 2 Tool tip side 3 Tool shank side 4 Nick 5 Tool round end round 6 Tool shank round 7 Nick groove bottom 8 Nick groove bottom 9 Nick groove 10 Straight line 11 Convex curve 12 Acute angle 13 Obtuse angle 14 Concave arc-shaped curve 15 Edge portion D Tool diameter R1 Tool tip side round radius R2 Tool shank side round radius R3 Concave radius R
θ Twist angle of tool outer peripheral edge b Parallel line to end mill twist angle H Nick depth

Claims (2)

On the outer periphery of the rotary tool body having a plurality of outer peripheral blades, in an end mill in which a plurality of nicks for separating chips from the tool tip side toward the shank side are arranged at intervals,
When the nick and the outer peripheral blade are viewed in a cutting plane parallel to the twist angle of the end mill, both ends of each nick are smoothly connected to the outer peripheral blade adjacent to the nick by rounding,
The round radius on the tool tip side of each nick is smaller than the round radius on the tool shank side of the nick,
The bottom end of the nick groove is connected to the roundness on the tool shank side with a straight line or a convex curve toward the nick groove, or connected with a combination of the straight line and a convex curve toward the nick groove. A nicked end mill.   When the tool diameter of the nicked end mill is D, the round radius on the nick tool tip side is 0.01D to 0.03D, and the round radius on the nick tool shank side is 1. The end mill with a nick according to claim 1, wherein the nick depth is 0.01D to 0.05D at 5 to 2 times.

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