JP2005125465A - End mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an end mill which is prevented from chipping and breakage at the time of thrust machining, to thereby carry out machining with high efficiency. <P>SOLUTION: According to the structure of the end mill, blade contact of a gash 6a extends up to a blade backside of a peripheral cutting edge 4a in an end cutting edge 5a, and an auxiliary groove 7a is formed in a ridge portion where the gash 6a and a twisting groove 3a intersects each other. Therefore when chips produced due to cutting operation of the end cutting edge 5a is lifted along a rake face, the chips are floated from the rake face by the auxiliary groove 7a, which leads to reduction of a length of chips affecting the cutting, i.e. a contact area between each of the chips and the rake face, to thereby minimize cutting resistance. As a result, chipping and breakage of the cutting edges can be prevented at the time of thrust machining, so that feeding speed at the time of thrust machining is increased to shorten a machining time, and accordingly grooving of a metal mold can be carried out with high efficiency. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an end mill, and more particularly, to an end mill capable of performing high-efficiency processing by preventing blade chipping and breakage during piercing.

  In the dent machining of the mold using the end mill, the end mill is first driven to move in the axial direction (or the direction including the axial center) with respect to the workpiece while the end mill is driven to rotate around the axial center. Then, the end mill is laterally fed in a direction intersecting the axis (for example, a direction perpendicular to the axis).

  By the way, in the side milling of the end mill, since the side opposite to the cutting side is in an open state, it is hardly necessary to consider the chip discharge. However, in the piercing process, the chip discharge is a problem. Therefore, in an end mill that performs such thrusting, it is common to provide a gash on the rake face of the bottom blade in order to ensure the machinability of the bottom blade and the capacity of the tip room.

In particular, in this piercing process, it is necessary to prevent chipping near the outer peripheral edge of the bottom blade having a high cutting speed. Therefore, for example, Japanese Patent Application Laid-Open No. 1-216710 describes an end mill that is configured to prevent the chipping of a blade by providing a gash to the back of the outer peripheral blade to increase the edge angle of that portion. (Patent Document 1).
JP-A-1-216710 (FIGS. 1 to 4 etc.)

  However, just by providing a gash on the rake face of the bottom blade as in the above-mentioned end mill, the chip room capacity is still insufficient at the time of thrusting, and the chips can be smoothly discharged smoothly. Therefore, there was a problem that the chipping and breakage of the blade could not be prevented appropriately.

  As a result, for example, in the dent processing of the mold, in order to prevent blade chipping at the time of piercing processing, the feed speed must be delayed or step processing must be performed, and the processing time increases accordingly. There was a problem that processing efficiency deteriorated.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an end mill capable of performing high-efficiency machining by preventing blade chipping and breakage during piercing.

  In order to achieve this object, a counterbore end mill according to claim 1 is provided with a tool body rotated about an axis, a twist groove recessed by being twisted about the axis of the tool body, and along the twist groove. An outer peripheral blade, a bottom blade connected to the outer peripheral blade and formed at the bottom of the tool body, and a gash forming a rake face of the bottom blade, The tool body is provided with three or more pieces, and at least two of the bottom blades of the three or more bottom blades have a secondary groove at a ridge line portion where the gasche and the twisted groove intersect on the rake face side. It is recessed.

  According to the counterbore end mill according to claim 1, at the time of counterbore machining, at least a part of the chips generated by the cutting action of the bottom blade and rising along the rake face of the bottom blade is the bottom blade. It is lifted from the rake face by a sub-groove recessed in the ridge line portion between the ridge and the torsion groove. As a result, the chip length involved in cutting, that is, the contact area between the chip and the rake face is reduced, and the cutting resistance is reduced accordingly.

  The end mill according to claim 2 is the end mill according to claim 1, wherein the sub-groove has a separation distance between the end edge on the bottom blade side and the bottom blade with respect to the outer diameter D of the outer peripheral blade. Thus, at least at the shortest distance portion, the distance is approximately 0.12D or less.

  The end mill according to claim 3 is the end mill according to claim 1 or 2, wherein the sub-groove has an end edge on the outer peripheral blade side at least approximately 0.05D with respect to the outer diameter D of the outer peripheral blade. It is configured to be separated from the outer peripheral end of the tool body by the above distance.

  The end mill according to claim 4 is the end mill according to any one of claims 1 to 3, wherein the auxiliary groove has an end edge on the axis side of the main body tool with respect to an outer diameter D of the outer peripheral blade. It is configured to be separated from the axis of the tool body by a distance of at least about 0.15D.

  The end mill according to claim 5 is the end mill according to any one of claims 1 to 4, wherein the gasche extends beyond the bottom edge so that at least two bottom edges are missing in the vicinity of the axis of the tool body. A missing gash formed, and an extending gash formed in a range not exceeding the bottom blade so as to extend the remaining bottom blade to at least the axial center of the tool body, and by the extending gash On the rake face side of the bottom blade on which the rake face is formed, or on the rake face side of the bottom blade extending to the axis of the tool body, the sub-groove is recessed, but by the missing gash The sub-groove is not recessed on the rake face side of the bottom blade where the axial center side of the tool body is missing and the rake face is formed by the missing gash.

  According to the end mill of the first aspect, the sub-groove is recessed in the ridge line portion on the rake face side of the bottom blade where the gasche and the twisted groove intersect. Therefore, there is an effect that the capacity of the chip room can be secured by the sub-groove. Furthermore, since the chip rising along the rake face can be lifted from the rake face by the sub-groove, the chip length involved in cutting, that is, the contact area between the rake face and the rake face can be reduced. Therefore, there is an effect that the cutting resistance can be reduced, and as a result, there is an effect that the chip can be discharged smoothly and the chipping and breakage at the time of piercing can be prevented. Thereby, since the feed speed at the time of piercing can be increased and the processing time can be shortened, there is an effect that, for example, dent processing of a mold can be performed with high efficiency.

  In addition, since the sub-groove has a ridge line where the gash and the twisted groove intersect, a space formed by the gash and the twisted groove exists around the sub-groove. Therefore, using such a space, it is possible to arrange a processing tool such as a grindstone so as to be opposed to the planned recessed portion of the sub-groove, and to secure a sufficient space for reciprocating the processing tool. Further, the concave groove is formed by removing the convex ridge line portion, and there is no need to perform complicated processing such as forming a concave portion on a flat surface. As a result, the sub-groove can be easily processed, and the processing cost can be reduced accordingly.

  According to the end mill of the second aspect, in addition to the effect achieved by the end mill of the first aspect, the separation distance at which the edge portion of the sub-groove on the bottom blade side is separated from the bottom blade is relative to the outer diameter D of the outer peripheral blade. Thus, at least at the shortest distance portion, the distance is about 0.12 D or less, that is, the distance that is shorter than the distance that the chips travel along the rake face before the blade separates itself. Therefore, since the chips can be lifted from the rake face by the auxiliary groove before the chips are separated from the rake face by themselves, the contact area between the chips and the rake face is reduced accordingly, and the cutting is performed. There is an effect that the resistance can be surely reduced.

  According to the end mill of the third aspect, in addition to the effect produced by the end mill according to the first or second aspect, the sub-groove has at least substantially the end edge portion on the outer peripheral blade side with respect to the outer diameter D of the outer peripheral blade. It is configured to be separated from the outer end of the tool body by a distance of 0.05D or more. Therefore, since a sufficient separation distance can be ensured between the cutting edge of the outer peripheral blade and the sub-groove, there is an effect that the cutting edge strength of the outer peripheral blade can be suppressed from being lowered due to the recessed groove. .

  Even when the sub-groove is disposed at a predetermined distance from the outer peripheral end of the tool body to the axial center as described above, the torsion groove is recessed in the rake face on the outer peripheral end side. Such twisted grooves can raise chips from the rake face and suppress an increase in cutting resistance.

  According to the end mill of the fourth aspect, in addition to the effect produced by the end mill according to any one of the first to third aspects, the auxiliary groove has an end edge on the axial center side of the tool body, and an outer diameter D of the outer peripheral blade. On the other hand, it is configured to be separated from the axis of the tool body by a distance of at least about 0.15D. Therefore, since the separation distance between the axial center side of the tool body or the gash surface and the secondary groove can be increased, a space for reciprocating movement of a processing tool such as a grindstone can be secured accordingly. There is an effect that the machining tool and the tool main body can be prevented from interfering with each other when the concave machining is performed.

  As a result, in the machining process for forming the sub-groove, there is a margin in the movement accuracy of the machining tool, so that advanced control can be eliminated, and the machining cost can be reduced accordingly. There is an effect. Further, there is an effect that it is possible to prevent the machining tool from inadvertently contacting the tool body and reducing the rigidity of the tool body due to the contact.

  Note that the cutting speed of the bottom blade decreases as it approaches the axial center side of the tool body, and it is not originally necessary to provide a concave groove on the rake face. Therefore, as described above, by separating the machining range of the sub-groove by a predetermined distance from the axis of the tool body, it is possible not only to prevent interference between the machining tool and the tool body at the time of concave machining, but also unnecessary. Thus, there is an effect that the processing cost can be reduced correspondingly by eliminating the need for the concave groove forming process.

  According to the end mill of the fifth aspect, in addition to the effect produced by the end mill according to any one of the first to fourth aspects, the bottom blade on which the rake face is formed by the extending gash, or the axial center of the tool body A sub-groove is formed only on the rake face side of the extended bottom blade, the axial center side of the tool body is missing due to the missing gash, and the rake face side is formed by the missing gash. Does not form minor grooves. In other words, since the secondary groove is formed only on the rake face side of the bottom blade having a relatively high rigidity and the secondary groove is not formed on the rake face side of the bottom blade having a low rigidity, the rigidity of the entire tool is reduced. Uniformity can be achieved, and as a result, the tool life can be improved.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a front view of an end mill 1 in one embodiment of the present invention, and FIG. 2 is a bottom view of the end mill 1 as viewed from the direction of arrow II in FIG. First, the overall configuration of the end mill 1 will be described with reference to FIGS. 1 and 2.

  The end mill 1 is a solid-type end mill that mainly includes a tool body 2 and torsion grooves 3a to 3c, outer peripheral blades 4a to 4c, and bottom blades 5a to 5c formed in the tool body 2. The end mill 1 is moved while being rotationally driven about the axis L by the rotational force of a machining machine such as a machining center being transmitted through a holder (not shown) that holds the shank 2 a of the tool body 2. The workpiece is cut.

  The end mill 1 of the present embodiment is particularly configured as a tool suitable for thrusting that is moved in the direction of the axis L with respect to the workpiece, and when performing such drilling, the bottom blade 5a. Chips generated by the cutting action of ˜5c can be discharged smoothly, and chipping and breakage can be effectively suppressed.

  The tool body 2 is made of a cemented carbide obtained by pressure-sintering tungsten carbide (WC) or the like. On the base side (left side in FIG. 1), as shown in FIG. In addition to being formed in a columnar shape, torsion grooves 3a to 3c, outer peripheral blades 4a to 4c, bottom blades 5a to 5c and the like are formed on the other end side (right side in FIG. 1) of the shank portion 2a.

  As shown in FIG. 1, the torsion grooves 3 a to 3 c are recessed by being twisted around the axis L of the tool body 2, and the outer peripheral blades 4 a to 4 c are along the ridge lines of the respective torsion grooves 3 a to 3 c. Is formed. In this embodiment, the outer diameters D of the outer peripheral blades 4a to 4c are D = φ12 mm, and the twist angle is 45 °. However, it is naturally possible to change this value as appropriate according to the cutting conditions.

  The bottom blades 5a to 5c are connected to the outer peripheral blades 4a to 4c, respectively, and are formed to have a clearance angle of 2 ° 30 'at the bottom of the tool body 2 (right side in FIG. 1). As shown in FIG. 1 and FIG. 2, these bottom blades 5 a to 5 c have contact with the blades of the gash 6 a to 6 c up to the back of the outer peripheral blade 4, and the bottom blades 5 a to 5 c are caused by the respective gash 6 a to 6 c. Each rake face is formed.

  In the present embodiment, the rake angle of the bottom blades 5a to 5c is 3 °, the second angle is 5 ° 30 ', and the third angle is 13 °, and the gashes angles of the gashes 6a to 6c are 45 °. The opening angle is 60 °. However, it is naturally possible to change these values as appropriate according to the cutting conditions.

  As shown in FIG. 1, sub-grooves 7a and 7b are recessed in the rake face of the bottom blades 5a and 5b. The sub grooves 7a and 7b are concave portions for lifting chips rising along the rake face of the bottom blades 5a and 5b from the rake face, and the twist grooves 3a and 3b and the gashes 6a and 6b intersect. It is recessed in the ridgeline. Here, the detailed configuration of the sub-grooves 7a and 7b will be described with reference to FIG.

  FIG. 3 is a partial view of the end mill 1 viewed from the direction of arrow III in FIG. In addition, since the subgroove 7b provided in the scoop surface side of the bottom blade 5b has the same configuration as the subgroove 7a, the description thereof is omitted.

  As described above, the bottom blade 5a has the contact of the gash 6a up to the back of the outer peripheral blade 4a, and the secondary groove 7a is formed at the ridge line portion where the gash 6a and the twist groove 3a intersect as shown in FIG. It is recessed.

  Therefore, when chips generated by the cutting action of the bottom blade 5a rise along the rake face, the chips can be lifted from the rake face by the auxiliary groove 7a. Thus, the contact area between the chips and the rake face can be reduced, and the cutting resistance can be reduced accordingly. As a result, it is possible to smoothly discharge chips and prevent chipping or breakage during piercing.

  Further, since the auxiliary groove 7a is provided with a ridge line portion where the gash 6a and the twisted groove 3a intersect, a space formed by the gash 6a and the twisted groove 3a exists around the auxiliary groove 7a. Therefore, using such a space, a processing tool such as a grinding wheel can be disposed opposite to the planned recess portion of the sub-groove 7a, and a space for reciprocating the processing tool can be secured. Furthermore, the recessing process of the sub-groove 7a may be performed by scraping the convex ridgeline part, and for example, it is not necessary to perform a complicated process such as recessing a recess in a plane. As a result, the sub-groove 7a can be easily processed, so that the processing cost can be reduced accordingly.

  Here, the separation distance H at which the edge of the sub-groove 7a on the bottom blade 5a side (upper side in FIG. 3) is separated from the bottom blade 5a is at least the shortest distance portion with respect to the outer diameter D of the outer peripheral blades 4a to 4c. In this case, it is preferable to configure so as to be approximately 0.12D or less. As a result, the chips can be lifted from the rake face by the sub-groove 7a before the chips are separated from the rake face by themselves, so that the contact area between the chips and the rake face is reduced accordingly. This is because cutting resistance can be surely reduced.

  The reason why the separation distance H is about 0.12D or less is as follows. That is, normally, the maximum cutting amount (feed amount per rotation) in thrusting is about 2% of the outer diameter D of the outer peripheral blades 4a to 4c, and the chips are about 6 times longer than the cutting amount. It is thought that after going up along the rake face for a while, the blades themselves are separated. Therefore, by setting the separation distance H to approximately 0.12D or less, the separation distance H can be set to a distance shorter than the distance traveled along the rake face until the chips separate themselves from the blade.

  In this embodiment, the separation distance H is H = 0.5 mm (= 0.042D). However, it is naturally possible to change this value as appropriate according to the cutting conditions.

  Here, the sub-groove 7a has an end edge portion on the outer peripheral blade 4a side (left side in FIG. 3) of the tool body 2 at a distance W1 of at least about 0.05D or more with respect to the outer diameter D of the outer peripheral blades 4a to 4c. It is preferable to be configured to be separated from the outer end (outer end of the bottom blade 5a) toward the axis L side (right side in FIG. 3). Thereby, since a sufficient separation distance can be secured between the outer peripheral blade 4a and the sub-groove 7a, it is possible to prevent the cutting edge strength of the outer peripheral blade 4a from being lowered due to the concave formation of the sub-groove 7a. is there.

  In this embodiment, the separation distance W1 is W1 = 1.2 mm (= 0.1D). However, it is naturally possible to change this value as appropriate according to the cutting conditions.

In this way, even when the auxiliary groove 7a is disposed at a distance W1 from the outer peripheral blade 4a to the axis L side (right side in FIG. 3), the rake face on the outer peripheral blade 4a side (left side in FIG. 3) (ie As shown in FIG. 3, the twist groove 3a is recessed in the rake face on the left side of FIG. 3 with respect to the sub groove 7a), so that the chips rising along the rake face on the outer peripheral blade 4a side. Is raised from the rake face by the torsion groove 3a, the contact area between the chips and the rake face is reduced, and the increase in cutting resistance is suppressed. Here, the auxiliary groove 7a is formed on the axis L side (FIG. 3). The right edge) is preferably configured to be separated from the axis L by a distance W2 of at least about 0.15D or more with respect to the outer diameter D of the outer peripheral blades 4a to 4c. Thereby, the separation distance between the axial center L side of the tool main body 2 or the gash surface and the auxiliary groove 7a can be increased, and a space for reciprocating movement of a processing tool such as a grindstone can be ensured accordingly. Therefore, when performing the concave machining of the sub-groove 7a, it is possible to prevent the machining tool from interfering with the axis L side of the tool body 2 or the gash surface.

  As a result, in the machining step for forming the sub-groove 7a, there is a margin in the movement accuracy of the machining tool, so that advanced control can be eliminated, and the machining cost can be reduced accordingly. it can. In addition, it is possible to prevent the machining tool from inadvertently contacting the tool body 2 or the like during the machining and reducing the rigidity of the tool body 2 due to the contact.

  In this embodiment, the separation distance W2 is W2 = 3.6 mm (= 0.3D). However, it is naturally possible to change this value as appropriate according to the cutting conditions.

  Note that the cutting speed of the bottom blade 5a decreases as it approaches the axis L side (the right side in FIG. 3) of the tool body 2, and the concave groove 7a is not originally required on the rake face. Therefore, as shown in FIG. 3, the machining range of the sub-groove 7a is limited to a range that is separated from the axis L of the tool body 2 by the distance W2, thereby preventing interference between the machining tool and the tool body 2 during the recessing machining. Not only can this be prevented, but the unnecessary machining of the sub-grooves 7a can be eliminated, thereby reducing the amount of machining and reducing the machining cost accordingly.

  Returning to FIG. 1 and FIG. As shown in FIG. 2, the gash 6a and the gash 6c are recessed beyond the bottom blade 5c and the bottom blade 5b so as to ensure the capacity of the chip pocket. 2 is missing near the axis L. On the other hand, the gash 6b is recessed in a range that does not exceed the bottom blade 6a so as to enable piercing, whereby the bottom blade 5a extends beyond the axis L of the tool body 2. .

  Therefore, as shown in FIG. 2, the rake face side and the flank face side of the bottom blade 5c are greatly shaved by the gash 6a and the gash 6c. Therefore, the bottom blade 5a and the bottom blade 5b disposed between the gash 6b and In comparison, the rigidity is relatively low. Therefore, in the end mill 1 of the present embodiment, as shown in FIG. 4, the sub-groove is not provided in the rake face side of the bottom blade 5c. FIG. 4 is a partial view of the end mill 1 viewed from the direction of arrow IV in FIG. 2 facing the bottom blade 5c.

  As described above, the auxiliary grooves 7a and 7b are recessed only on the rake face side of the bottom blades 5a and 5b having relatively high rigidity, and the auxiliary groove is provided on the rake face side of the bottom blade 5c having relatively low rigidity. Since the rigidity of each of the bottom blades 5a to 5c can be made uniform by not forming the recesses, only some of the bottom blades are chipped early compared to the other bottom blades. It is possible to improve the tool life of the end mill 1 as a whole by suppressing defects.

  Next, a cutting test performed using the end mill 1 configured as described above will be described with reference to FIG. In this cutting test, the thrust resistance value generated in the direction of the axis L when the end mill 1 is rotated around the axis L and the workpiece is moved in the direction of the axis L is performed. It is a test to measure.

  Detailed specifications of the cutting test are as follows: Work material: JIS-S50C, machine used: vertical machining center, cutting method: thrusting, cutting oil: not used (air blow), processing depth: 6 mm, presence or absence of pilot hole: None.

In this cutting test, step processing is not performed, and the cutting speed is in the range from 60 m / min (3185 min ⁻¹ ) to 120 m / min (6370 min ⁻¹ ), and the feed amount is 0.06 mm / rotation. To 0.18 mm / rotation (see FIG. 5).

  For the cutting test, the end mill 1 (hereinafter referred to as “the product of the present invention”) described in the above example was used. For comparison, a similar cutting test was performed on a conventional product having no sub-groove. The outer diameter D of the present invention product is D = φ6 mm, and the specifications of the auxiliary grooves 7a, 7b (separation distances H, W1, W2 from the outer peripheral blades 4a, 4b, etc.) are H = 0.25 mm (= 0), respectively. 0.042D), W1 = 1.2 mm (= 0.1 D), and W2 = 1.8 mm (= 0.3 D). Moreover, the sub-groove is not provided on the rake face side of the bottom blade 5c as described in the above embodiment (see FIG. 4). The difference between the product of the present invention and the conventional product is only the presence or absence of the auxiliary groove, and the other materials, dimensions, etc. are the same.

  FIG. 5 is a diagram showing the results of the cutting test. In FIG. 5, the “No.” column indicates the measurement No. It shows that measurement was performed for 12 types of cutting conditions. The values in the “maximum value” column and “average value” column indicate the maximum value and average value of the thrust resistance value measured from the start to the end of the piercing in each cutting condition. ing.

  Further, the “change rate” column of the product of the present invention indicates the change rate of the thrust resistance value of the product of the present invention with respect to the conventional product. For example, the “change rate” is “−25.3%” This shows that the thrust resistance value of the product of the present invention was reduced by 25.3% than the value of the thrust resistance value of the conventional product under the same cutting conditions.

  As shown in FIG. 5, the value of the thrust resistance value in the product of the present invention has a slight variation, but both the maximum value and the average value are smaller than the value of the thrust resistance value in the conventional product. The thrust resistance value is reduced by about 8% to 20% regardless of the cutting speed and the feed amount.

  That is, according to the product of the present invention, the sub-grooves 7a and 7b are recessed on the rake face side, whereby the chips are lifted from the rake face by the sub-grooves 7a and 7b, and the length of the chips involved in cutting. That is, it was confirmed that the contact area between the chips and the rake face can be reduced, and as a result, the cutting resistance can be reduced.

  In addition, measurement No. 1-No. In each cutting test shown in No. 12, no chipping or breakage of the bottom blades 5a to 5c was observed. That is, the auxiliary grooves 7a and 7b are recessed based on the separation distances H, W1 and W2 (see FIG. 3) shown in the above embodiment, and the auxiliary blades on the rake face side of the bottom blade 5c having relatively low rigidity are provided. In the case where the groove is not provided, the rigidity of the end mill 1 (bottom blades 5a to 5c, outer peripheral blades 4a to 4c, etc.) does not decrease due to the recessed grooves of the auxiliary grooves 7a and 7b. In addition, it was confirmed that the chip dischargeability can be secured at the same time.

  As described above, according to the end mill of the present invention, the capacity of the chip room can be secured by the auxiliary grooves 7a and 7b, and the contact area between the chips and the rake face can be reduced to reduce the cutting resistance. Since it can be reduced, chips can be discharged smoothly, and chipping and breakage during piercing can be prevented. As a result, step machining at the time of thrusting can be made unnecessary, and the feed rate in the axial direction can be increased, so that the machining time can be shortened accordingly, for example, the depression of the mold. Processing and the like can be performed with high efficiency.

  The present invention has been described based on the embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be easily made without departing from the spirit of the present invention. It can be guessed.

  For example, in the present embodiment, the case where the end shape of the end mill 1 is configured as a square end has been described. However, the end shape is not necessarily limited to this end shape. For example, the end mill 1 can be configured as a radius end. Similarly, in the present embodiment, the case where the end mill 1 is configured with three blades has been described, but it is naturally possible to configure the end mill 1 with four or more blades.

It is a front view of the end mill in one example of the present invention. It is the bottom view of the end mill 1 seen from the arrow II direction of FIG. FIG. 3 is a partial view of the end mill viewed from the direction of arrow III in FIG. FIG. 4 is a partial view of the end mill viewed from the direction of arrow IV in FIG. It is the figure which showed the result of the cutting test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 End mill 2 Tool main body 3a-3c Twist groove | channel 4a-4c Peripheral blade 5a-5c Bottom blade 6a, 6c Gash (gash for omission)
6b Gash (Gash for extension)
7a, 7b Sub-groove L Axis line H Separation distance W1 between the edge on the bottom blade side of the sub-groove and the bottom blade W1 Separation distance between the edge on the outer-blade side of the sub-groove and the outer edge of the tool body W2 Separation distance between the edge of the secondary groove on the axis side of the main body tool and the shaft center

Claims (5)

A tool body rotated about an axis, a twist groove recessed by being twisted around the axis of the tool body, an outer peripheral blade formed along the torsion groove, and the tool main body connected to the outer peripheral blade In an end mill provided with a bottom blade formed on the bottom of the gas and a gash forming a rake face of the bottom blade,
Three or more bottom blades are provided on the tool body, and at least two of the bottom blades of the three or more bottom blades have a ridge line where the gash and the twist groove intersect on the rake face side. An end mill characterized in that a sub-groove is provided in the part.   The sub-groove has a distance of about 0.12D or less at least in the shortest distance portion with respect to the outer diameter D of the outer peripheral blade with respect to the outer edge D of the outer peripheral blade. The end mill according to claim 1, wherein the end mill is configured as follows.   The sub-groove is configured such that an end edge portion on the outer peripheral blade side is separated from the outer peripheral end of the tool body by a distance of at least about 0.05 D with respect to the outer diameter D of the outer peripheral blade. The end mill according to claim 1 or 2, characterized in that.   The sub-groove is configured such that an end portion on the axis line side of the main body tool is separated from the axis of the tool main body by a distance of at least about 0.15D with respect to the outer diameter D of the outer peripheral blade. The end mill according to any one of claims 1 to 3, wherein the end mill is provided. The gash has a missing gash formed beyond the bottom edge so that at least two bottom edges are missing near the axis of the tool body, and the remaining bottom edge extends at least to the axis of the tool body. An extension gash formed in a range not exceeding the bottom blade to be installed,
On the rake face side of the bottom blade where the rake face is formed by the extending gash, or on the rake face side of the bottom blade extended to the axis of the tool body, the auxiliary groove is recessed. ,
The axial center side of the tool body is missing due to the missing gash, and the sub-groove is not recessed on the rake face side of the bottom blade where the rake face is formed by the missing gash. The end mill according to any one of claims 1 to 4.

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