JP2005125433A - End mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the clogging of chips in a gash of the chips generated by a bottom blade. <P>SOLUTION: In this end mill, the gash 8 is formed in a tip side opening groove part of a chip discharge groove 4 of the tip part outer periphery of an end mill body 1, and the bottom blade 10 is formed in a tip side edge angle part of a bottom blade rake surface 9 of this gash 8. At least one of a crossing ridgeline part 15 of the bottom blade rake surface 19 and a gash bottom surface 12 and a crossing ridgeline part 16 of the gash bottom surface 12 and a gash wall surface 13, is formed in a concave curve shape in a cross section orthogonal to the extending direction of the crossing ridgeline parts 15 and 16. A radius of curvature of a concave curve formed by the cross section of these crossing ridgeline parts 15 and 16, is formed larger than the inner peripheral side on the outer peripheral side of the end mill body 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an end mill in which an outer peripheral blade is formed on the outer periphery of a tip end portion of an end mill body that is rotated around an axis, and a bottom blade is formed on the tip.

As this type of end mill, for example, in Patent Document 1, the bottom blade has a lead rake surface (for the purpose of performing machining such as drilling or pocket machining in the axial direction of the end mill with high efficiency. The outer edge rake face is extended over the rake face, the gash part is formed in a convex shape, and the boundary part where the lead rake face and the gash part intersect is formed with R. ing.
Japanese Patent Laid-Open No. 10-217024

  By the way, in the above-mentioned Patent Document 1, when forming the boundary portion between the outer peripheral edge rake face (lead rake face) extended so as to intersect the bottom edge and the gash portion with R, this boundary portion is defined as the boundary portion. Therefore, grinding is performed with a grindstone having a roundness corresponding to R, and therefore the size of R given to the boundary portion is substantially equal from the inner peripheral side to the outer peripheral side of the end mill body. However, in such a cutting with the bottom edge of the end mill, the inner end of the end mill has a small rotating diameter around the axis, so that less chips are generated, whereas the outer peripheral side has a large rotating diameter. Since the amount of chips to be produced is increased and the chips generated on the inner peripheral side are pushed out through the gash and discharged to the outer peripheral side, the boundary part on the outer peripheral side of the gash, that is, the bottom edge rake face (Patent Document 1) In this case, chips are cut at the cross ridge line between the scoop surface of the outer peripheral edge and the gasche bottom face facing the tip side of the end of the gash end mill, and at the cross ridge line part of the gasche bottom face facing the rear side in the direction of rotation of the end of the gash end mill There was a problem that clogging was likely to occur.

  Further, like the end mill described in Patent Document 1, the bottom blade is formed so as to intersect with the extension of the outer peripheral edge rake face, that is, the outer peripheral edge rake face is extended to the tip side edge ridge portion extended with the lead as it is. When the bottom blade is formed, the axial rake angle of this outer peripheral blade becomes the axial rake angle of the bottom blade as it is, and in such an end mill, the axial rake angle of the outer peripheral blade is usually 30 ° or more. The rake angle in the axial direction of the bottom blade is 30 ° or more, and it becomes impossible to secure the edge angle of the bottom blade, so that the strength of the blade edge is insufficient and the bottom blade may be damaged. Further, when the bottom blade is formed on the extension of the peripheral blade rake face in this way, the chips generated by the tip side portion of the peripheral blade at the time of side cutting of the workpiece using the tip side of the end mill main body are removed. Intrusion into the inner peripheral side of the narrow gasche along the edge may interfere with the chips generated by the bottom blade and cause chip clogging.

  The present invention has been made under such a background, can prevent clogging of chips generated in the bottom edge of the gash, and further prevent the peripheral edge while ensuring the edge strength of the bottom edge. In addition to digging, it is possible to improve the discharge of chips generated by the bottom blade and perform efficient machining not only for digging but also for side cutting and grooving of workpieces. The aim is to provide a possible end mill.

  In order to solve the above problems and achieve such an object, according to the present invention, a chip discharge groove is formed on the outer periphery of the end portion of the end mill body rotated around the axis, and the end mill rotation direction of the chip discharge groove is changed. The facing surface is a rake face on the outer peripheral edge, and an outer peripheral blade is formed on the outer peripheral side ridge portion, and a gash is formed in the groove portion on the tip end side of the end mill body of the chip discharge groove. An end mill in which a surface facing the rotation direction is a bottom blade rake surface, and a bottom blade whose outer peripheral end is continuous with the tip of the outer peripheral blade is formed on a tip side ridge portion of the bottom blade rake surface, A cross ridge line portion between the bottom edge rake face and the gasche bottom face facing the tip end side of the end mill body of the gasche, and a gasche wall face facing the gasche bottom face and the rear side in the end mill rotation direction of the gasche At least one of the difference ridge line portions is formed to have a concave curve shape in a cross section perpendicular to the direction in which the cross ridge line portion extends, and the radius of curvature of the concave curve formed by the cross section of the cross ridge line portion is equal to that of the end mill body. The outer peripheral side is larger than the inner peripheral side.

  In addition, in order to prevent interference with chips generated by the outer peripheral blade while ensuring the edge strength of the bottom blade as described above, the bottom blade rake face has an axial rake angle of the bottom blade. The gash is formed so as to be convex with respect to the rake face of the outer peripheral blade so as to be smaller than the rake angle in the axial direction, and at least one of the gash bottom surface and the gash wall surface of the gash is inside the end mill body. It is desirable to have a convex curved shape that curves from the circumferential side toward the outer circumferential side. Further, when the bottom edge rake face is formed to be bent convexly with respect to the outer edge edge rake face so that the axial rake angle of the bottom edge is smaller than the axial rake angle of the outer edge edge. In this case, the cross ridge line portion between at least one of the bottom edge rake face and the gash bottom face and the outer peripheral edge rake face or the bottom face of the chip discharge groove has a cross section orthogonal to the direction in which the cross ridge line portion extends. It is desirable to have a convex curved surface that forms a curve.

  Furthermore, it is desirable that at least one of the bottom edge rake face and the gash bottom surface is at least partly concave and convex, and it is desirable that a coolant hole be opened in the gash bottom surface.

  Therefore, according to the end mill having the above-described configuration, at least one of the intersecting ridge line portion between the bottom edge rake face and the gash bottom surface and the intersecting ridge line portion between the gash bottom surface and the gash wall surface has a concave cross section, that is, a concave shape. Since it is formed in a curved surface, it is possible to curl the chips of the bottom blade flowing out toward the bottom surface and the wall surface of the gash by rubbing the rake face of the bottom blade without causing clogging. And since the radius of curvature of the concave curve formed by the cross section of at least one of the intersecting ridge lines is made larger on the outer peripheral side of the end mill body than on the inner peripheral side, the outer peripheral side of the bottom blade where the amount of generated chips increases. Then, it is possible to curl the chips more gently to reduce the resistance, and to discharge more smoothly and surely into the chip discharge groove on the outer peripheral side.

  In addition, when the bottom edge rake face is bent convexly with respect to the outer edge edge rake face so that the axial edge rake angle of the bottom edge is smaller than the axial edge rake angle of the outer edge edge, Since the axial rake angle of the bottom blade is on the negative side of the rake angle in the axial direction, the edge angle of the bottom blade must be increased to ensure the edge strength regardless of the axial rake angle of the outer peripheral blade. It is possible to prevent the bottom blade from being damaged. In this way, the bottom edge rake face is bent in a convex shape with respect to the outer edge edge rake face, so that the chips generated on the tip side of the outer edge blade enter the inner circumference side of the gash as it is, and the bottom edge There is no longer any possibility of chip clogging by interfering with the generated chips.

  On the other hand, by forming at least one of the gash bottom surface and gash wall surface of the gasche into a convex curved shape that curves from the inner peripheral side to the outer peripheral side of the end mill body, the cross-sectional area of the gasche increases toward the outer peripheral side. As the rate of increase gradually increases, chip separation of chips scraping the gash bottom surface and gash wall surface, which are convex curved surfaces, is improved. Accordingly, the chips generated by the bottom blade can be smoothly guided from the inner peripheral side where the amount of generated chips is small toward the outer peripheral side where the amount of generated chips is large, and the resistance due to the rubbing with the gash bottom surface and the wall surface can be reduced. Thus, it is possible to reliably discharge the chips of the bottom blade guided to the outer peripheral side through the chip discharge grooves having a large pocket capacity.

  Furthermore, a convex curved surface in which the cross section perpendicular to the direction in which the cross ridge line portion extends forms a convex curve at the cross ridge line portion between at least one of the bottom rake face and the gash bottom face and the bottom face of the outer peripheral rake face or the chip discharge groove By making it into a shape, it becomes possible to facilitate smooth chip discharge by improving the chip separation from the gasche toward the chip discharge groove. Furthermore, if at least one of the bottom blade rake face and the gash bottom surface on which the chips generated by the bottom blade scrape is made to have an uneven shape, chips on the bottom blade rake surface and the gash bottom surface are formed. The contact area can be reduced to reduce the resistance caused by scratching. Here, to make the cross-section of the bottom edge rake face or the gash bottom as described above, the surface itself is formed into a corrugated shape, or a dot-like projection or recess is formed on the face. do it.

  In addition, when the coolant hole is opened on the bottom surface of the gash, it is possible to further improve the chip discharging property by a coolant such as cutting fluid or air ejected from the coolant hole. Since the contact area of the chips scraping the gash bottom surface is reduced due to the opening of the surface, the resistance due to scratching can be further reduced. In addition, the end mill having a gash shape having the above-described configuration can be formed by grinding with a grindstone as in the above-mentioned Patent Document 1, but particularly when the bottom edge scoop surface and the gash bottom surface are uneven. For example, an end mill main body having a desired shape may be formed by injection molding and sintering an end mill material such as cemented carbide.

  1 to 3 show a first embodiment of the present invention. In the present embodiment, the end mill body 1 is formed by injection molding and sintering an end mill material such as cemented carbide as described above, and the rear end of the end mill body 1 is a circle centered on the axis O. A columnar shank portion 2 and a front end portion are a cutting edge portion 3, and an outer periphery of the cutting blade portion 3, that is, an outer periphery of a front end portion of the end mill main body 1, opens to the front end of the end mill main body 1 and is on the rear end side. A plurality of chips (four in this embodiment) are formed at equal intervals in the circumferential direction around the axis O toward the rear side in the end mill rotation direction T and twisted at a constant twist angle.

  And the surface which faces the end mill rotation direction T side of these chip discharge grooves 4 is the outer peripheral edge scoop surface 5, and the outer peripheral edge 6 is formed on the outer peripheral side ridge. Accordingly, the outer peripheral blade 6 is given an axial rake angle according to its twist angle at which the chip discharge groove 4 is twisted about the axis O, and the axial rake angle of the outer peripheral blade 6 is usually 30 as described above. It is set to a positive angle of more than °. The outer peripheral blade rake face 5 usually has a cross section orthogonal to the axis O between the outer peripheral blade 6 and the bottom surface 7 of the chip discharging groove 4 where the chip discharging groove 4 is most recessed on the inner peripheral side of the end mill body 1. It is formed in the shape of a concave curved surface that is recessed rearward in the end mill rotation direction T, whereby the outer peripheral blade 6 is given a positive rake angle (0 ° or negative angle in some cases) according to cutting conditions and the like.

  On the other hand, a gash 8 is formed in the open groove portion on the tip end side of the end mill body 1 of the chip discharge groove 4 twisted about the axis O in this way. This gash 8 is provided on the outer peripheral blade rake face 5 side of the open groove portion of the chip discharge groove 4, that is, on the rear side in the end mill rotation direction T, along the outer peripheral blade rake face 5 from the inner peripheral side of the end mill body 1 to the outer peripheral side. The surface facing the end mill rotation direction T side is a bottom blade rake surface 9, and the outer peripheral edge is at the tip side ridge portion of the bottom blade rake surface 9. A bottom blade 10 that is continuous with the tip of the outer peripheral blade 6 is formed. The end mill of the present embodiment is a square type end mill in which the bottom blade 10 intersects the outer peripheral blade 6 with an angle so that the outer peripheral end and the distal end are continuous. It is also possible to apply the present invention to a radius type end mill in which 10 is continuous while drawing a convex curve such as a 1/4 arc on the outer peripheral edge 6.

  Here, the bottom edge rake face 9 is substantially parallel to the axis O so that the tip side of the outer edge rake face 5 is smaller than the axial rake angle of the outer edge 6. Accordingly, the rake angle in the axial direction of the bottom blade 10 is set to around 0 °. Further, the flat surface formed by the bottom edge rake face 9 is also disposed at a position substantially including the axis O, whereby the bottom edge 10 is substantially along a straight line intersecting the axis O when viewed from the front in the direction of the axis O. The rake angle in the radial direction is set to about 0 °. Then, the bottom blade rake face 9 is formed so that the axial rake angle of the bottom blade 10 is smaller than the axial rake angle of the outer peripheral blade 6 in this way. In the present embodiment, the surface 5 is formed so as to be bent in a convex shape so as to intersect an obtuse angle with each other at the intersecting ridge line portions 11.

  The bottom edge rake face 9 may be formed over the entire width of the outer peripheral edge rake face 5 in the radial direction of the end mill body 1 on the tip side of the chip discharge groove 4. In this case, the bottom edge 10 Is formed in a straight line so as to substantially follow the straight line as described above over its entire length. Further, the bottom edge rake face 9 may be formed only on the inner peripheral side of the outer peripheral edge rake face 5 in the radial direction. In this case, the inner peripheral side of the bottom edge 10 is substantially along the straight line. On the other hand, the outer peripheral side of the bottom blade 10 is formed at the ridge portion on the tip side of the outer peripheral blade rake face 5, and a cross section perpendicular to the axis O of the outer peripheral blade rake face 5 is formed. As described above, when it is formed in a concave curved shape that is recessed toward the rear side in the end mill rotation direction T, it is formed in a concave curve shape that is recessed toward the rear side in the end mill rotation direction T with respect to the straight line when viewed from the front in the axis O direction. Become.

  Further, a bottom surface of the gash 8 facing the front end side of the end mill body 1, that is, a gash bottom surface 12 is formed on the bottom edge rake face 9 on the rear end side of the end mill body 1 and in the end mill rotation direction T side. Further, a gash wall surface 13 facing the rear side in the end mill rotation direction T is formed on the end mill rotation direction T side so as to face the bottom blade rake surface 9, and these gash bottom surface 12 and gash wall surface 13 and the bottom blade rake surface are formed. 9 defines the concave groove formed by the gash 8. In the present embodiment, both the gash bottom surface 12 and the gash wall surface 13 are formed in a convex curved shape that curves from the inner peripheral side to the outer peripheral side of the end mill body 1.

  That is, as shown in FIG. 2, the gash bottom surface 12 of the end mill body 1 is curved while drawing a single convex curved surface that protrudes toward the outer periphery of the end as it goes from the inner periphery to the outer periphery. It is formed to face the rear end side. Accordingly, the groove depth of the groove formed by the gash 8 by the gash bottom surface 12 is gradually increased from the inner peripheral side to the outer peripheral side of the end mill main body 1, and the depth of the groove is gradually increased. To be. In addition, in this embodiment, the portion on the outer peripheral side of the gash bottom surface 12 forms a flat surface that smoothly contacts the convex curved surface and extends to the outer peripheral side of the rear end, and intersects the ridge line portion 14 with the bottom surface 7 of the chip discharge groove 4. In FIG. 1, the angle is made to intersect with an obtuse angle.

  Further, the gash wall surface 13 is curved so as to draw a convex curved surface that protrudes rearward in the end mill rotation direction T from the inner peripheral side to the outer peripheral side of the end mill body 1, and the end mill rotation of the chip discharge groove 4 The obtuse angle intersects the wall surface facing the rear side in the direction T with an angle. Accordingly, the gap between the gash wall surface 13 and the flat bottom rake face 9, that is, the groove width of the groove formed by the gash 8, gradually increases from the inner peripheral side toward the outer peripheral side of the end mill body 1. Moreover, the rate of enlargement is gradually increased. In other words, the groove formed by the gash 8 is configured such that the groove width and the groove depth are gradually reduced, that is, narrowed toward the inner peripheral side of the end mill body 1.

  Of the bottom edge rake face 9, the gash bottom face 12, and the gash wall face 13 that define the gash 8, the cross ridge line portion 15 between the bottom edge rake face 9 and the gash bottom face 12 in the present embodiment is shown in FIG. 3. As shown in FIG. 2, the curved surface is formed in a concave curved surface that smoothly contacts the bottom edge scoop surface 9 and the gash bottom surface 12 so as to form a concave curve in a cross section orthogonal to the direction in which the intersecting ridge line portion 15 extends. In the cross section, the radius of curvature R of the concave curve formed by the intersecting ridge line portion 15 is made larger on the outer peripheral side of the end mill body 1 than on the inner peripheral side. In particular, in the present embodiment, the concave curve is concave. As a circular arc, the radius R of the concave arc gradually increases from the inner peripheral side of the end mill body 1 toward the outer peripheral side.

  On the other hand, in the present embodiment, the gash wall surface 13 is formed so as to be substantially linear in a cross section orthogonal to the intersecting ridge line part 15 as shown in FIG. 3, and in the intersecting ridge line part 16 with the gash bottom surface 12. They intersect each other at an angle and an obtuse angle. Further, the gash bottom surface 12 and the bottom edge rake surface 9 are also arranged in directions intersecting each other at an obtuse angle via the intersecting ridge line portion 15 having a concave curved surface shape. In FIG. 2, the gap between the bottom blade rake face 9 and the gash wall face 13 facing each other is formed so as to gradually increase toward the groove opening side of the concave groove, that is, toward the tip end side of the end mill body 1.

  Furthermore, a coolant hole 17 is opened in the gash bottom surface 12. The coolant hole 17 is formed in the end mill body 1 from the rear end surface of the shank portion 2 to the front end side, for example, and is supplied from the shank portion 2 held by the spindle of the machine tool or the like. A coolant such as cutting fluid or air can be jetted into the gash 8 from the gash bottom 12 toward the tip. Further, the coolant hole 17 is formed in parallel with the axis O in the present embodiment in which the end mill body 1 is formed by injection molding as described above, and the cross section perpendicular to the axis O is circular, The gash bottom 12 is opened at a substantially central portion in the inner and outer circumferential directions.

  In the end mill of the present embodiment in which four pieces of chip discharge grooves 4 are formed in the end mill body 1, an outer peripheral blade 6, a gash 8, and a bottom blade 10 are formed on the outer periphery and the tip of each chip discharge groove 4, respectively. However, among the pair of chip discharge grooves 4 positioned on the opposite sides of the axis O, the bottom blades 10 of the end mill body 1 end on the axis O, that is, from the vicinity of the rotation center. On the other hand, in the remaining pair of chip discharge grooves 4, the bottom blade 10 extends to the outer peripheral side from a position slightly away from the rotation center to the outer peripheral side, and at the tip of the outer peripheral blade 6. It is supposed to be continuous.

  In the end mill configured as described above, first, the axial rake angle of the bottom blade 10 is made smaller than the axial rake angle of the outer peripheral blade 6, specifically, the axial rake angle of the outer peripheral blade 6. Is 30 ° or more in accordance with the twist angle of the chip discharge groove 4, whereas the axial rake angle of the bottom blade 10 is around 0 °. Compared to the end mill described in the above-mentioned Patent Document 1, which is the rake angle in the axial direction of the blade, it is possible to ensure a large blade edge angle of the bottom blade 10 and maintain its strength. Therefore, it is possible to prevent a situation in which the bottom blade 10 is damaged during cutting and the life of the end mill body 1 is shortened, and smooth and stable machining can be promoted.

  On the other hand, the axial direction rake angle of the outer peripheral blade 6 formed on the outer peripheral side ridge portion of the outer peripheral blade rake surface 5 is thus formed by forming the bottom blade 10 at the distal side ridge portion of the lower blade rake surface 9. By making it smaller than these, the bottom edge rake face 9 and the outer peripheral edge rake face 5 are bent into a convex shape as described above and intersected with a step. For this reason, even if the chips generated by the tip side portion of the outer peripheral blade 6 flow to the inner peripheral side along the outer peripheral blade rake face 5, the chips are separated from the outer peripheral blade rake face 5 by this level difference in the gash 8. Since the inside of the chip discharge groove 4 is sent to the rear end side and discharged without entering the outer periphery, the outer periphery of the outer periphery of the gash 8 becomes smaller in groove width and groove depth toward the inner peripheral side as described above. The chips generated by the blade 6 do not interfere with the chips generated by the bottom blade 10. Therefore, even during side cutting or grooving of a workpiece in which chips are generated by the peripheral blade 6 together with the bottom blade 10, chip clogging in the gash 8 can be prevented and stable machining can be achieved.

  Further, in the present embodiment, the gash bottom surface 12 and the gash wall surface 13 of the gash 8 are formed in a convex curved shape that curves from the inner peripheral side to the outer peripheral side of the end mill body 1. The groove depth and groove width are also gradually increased toward the outer peripheral side opened to the chip discharge groove 4, that is, the cross-sectional area of the concave groove is gradually increased, and the rate of increase in the cross-sectional area is also toward the outer peripheral side. growing. For this reason, the chips generated by the bottom blade 10 and flowing into the gash 8 from the bottom blade rake face 9 are smoothly guided to the outer peripheral side as shown by white arrows in FIG. 1 and FIG. It can be guided to the discharge groove 4 and can be reliably discharged through the chip discharge groove 4. Moreover, the chips scraping the convex-shaped gash bottom surface 12 and the gash wall surface 13 in this way are well separated from the bottom surface 12 and wall surface 13, and thus reduce the resistance caused by friction between the gash bottom surface 12 and the wall surface 13 and the chips. Therefore, even if the axial rake angle of the bottom blade 10 is reduced as described above, the resistance in resistance to excavation such as drilling or pocketing that feeds the end mill body 1 in the direction of the axis O and performs cutting. Can be prevented from significantly increasing.

  In the present embodiment, both the gash bottom surface 12 and the gash wall surface 13 are formed in a convex curved shape that curves from the inner peripheral side to the outer peripheral side of the end mill body 1 as described above. In this case, one of the groove depth or the groove width of the gasche 8 increases with an increasing rate toward the outer peripheral side, and thus the above-described effect is achieved. It becomes possible. Further, at least one of the gash bottom surface 12 and the gash wall surface 13 is not a convex curved surface over the entire length thereof, but the groove depth of the gash 8 whose groove depth is sufficiently increased as in the present embodiment, for example. On the outer peripheral side, it may be a flat surface extending to the outer peripheral side of the rear end.

  In the end mill having the above-described configuration, the concave ridge line portion 15 of the bottom edge rake face 9 of the gash 8 and the gash bottom surface 12 has a concave curved surface so as to form a concave curve in a cross section perpendicular to the direction in which the cross ridge line portion 15 extends. Further, the radius of curvature R of the concave curve formed by the intersecting ridge line portion 15 is set to be larger on the outer peripheral side of the end mill body 1 than on the inner peripheral side, and therefore is generated by the bottom blade 10 and scoops the bottom blade. The chips flowing on the surface 9 are guided to the outer peripheral side as described above while being curled in a spiral shape by the concave curved surface formed by the intersecting ridge line portion 15 with the gash bottom surface 12, and are smoothly discharged. In addition, since the radius of rotation around the axis O is particularly large among the bottom blades 10 at this time, the curvature radius R of the intersecting ridge line portion 15 is also increased on the outer peripheral side where a large amount of chips is generated. In addition, the resistance can be reduced, and it is possible to prevent a situation where chips are clogged in the gash 8 because the chips are curled excessively small on the outer peripheral side. The chips generated by 10 can be more smoothly and reliably discharged to the chip discharge groove 4 having a large capacity on the outer peripheral side, and the chip discharge performance can be improved.

  In the present embodiment, only the intersecting ridge line portion 15 between the bottom edge rake face 9 and the gash bottom surface 12 is formed in a cross-sectional concave curve having a large curvature radius R on the outer peripheral side, and the gash bottom surface 12 and the gash wall surface 13 The intersecting ridge line portions 16 intersect with each other at an obtuse angle, but the intersecting ridge line portion 16 also has a concave cross-sectional shape in which the outer peripheral side has a larger radius of curvature R than the inner peripheral side, similar to the intersecting ridge line portion 15. In some cases, only the intersecting ridge line portion 16 has such a concave concave cross section, and at the intersecting ridge line portion 15, the bottom edge scoop surface 9 and the gash bottom surface 12 intersect at an angle. It may be. Further, in the case where both of the intersecting ridge line portions 15 and 16 are formed in a concave concave section having a radius of curvature R larger on the outer peripheral side than on the inner peripheral side, in the cross section orthogonal to the intersecting ridge line portion 15, It is desirable that the radius of curvature of the concave curve formed by 15 is larger than the radius of curvature of the concave curve formed by the intersecting ridge line portion 16 in order to curl the chips gradually and further reduce the resistance. However, when the crossing ridge line portions 15 and 16 are formed in a concave curve shape in this way, the radius of the cross section gradually increases toward the outer peripheral side including the crossing ridge line portions 15 and 16 and the gash bottom surface 12. It may be a half concave arc shape.

  Furthermore, in the present embodiment, a coolant hole 17 is opened in the gash bottom surface 12, and cutting fluid, air, or the like is ejected from the coolant hole 17 into the gash 8, thereby removing chips in the gash 8. The chip can be forcedly pushed into the chip discharge groove 4 to further improve the chip discharge performance. In addition, since the coolant hole 17 is formed in the gash bottom surface 12 in this way, the contact area between the chips rubbing the gash bottom surface 12 and the gash bottom surface 12 is reduced, so that the resistance due to the chip abrasion is further reduced. It is also possible to facilitate smooth and stable cutting.

  Next, FIG. 4 and FIG. 5 show the second and third embodiments of the present invention, respectively, and the same reference numerals are used for the parts common to the first embodiment shown in FIG. 1 to FIG. Will be omitted. That is, also in the second and third embodiments, at least one of the intersecting ridge line portion 15 between the bottom edge rake face 9 and the gash bottom surface 12 and the intersecting ridge line portion 16 between the gash bottom surface 12 and the unillustrated gash wall surface 13 is illustrated. Is formed so as to form a concave curve in a cross section orthogonal to the direction in which the intersecting ridge line portions 15 and 16 extend, and the curvature radius R of the concave curve formed by the cross section of the intersecting ridge line portions 15 and 16 is equal to that of the end mill body 1. The outer peripheral side is larger than the inner peripheral side.

  The gash bottom surface 12 of the gash 8 in the first embodiment is formed into a convex curved shape that curves from the inner peripheral side to the outer peripheral side of the end mill main body 1, and is flat on the outer peripheral side to form the chip discharge groove 4. In the second embodiment, first, the gash bottom surface 12 is bent from the inner peripheral side of the end mill body 1 to the outer peripheral side. Further, the cross ridge line portion 14 with the bottom surface 7 of the chip discharge groove 4 on the outer peripheral side of the gash bottom surface 12 is shown in FIG. 4 in a cross section orthogonal to the cross ridge line portion 14. In this way, a convex curved surface is formed so as to form a convex curve. In the present embodiment, the convex curved surface formed by the intersecting ridge line portion 14 is formed so as to be in smooth contact with both the bottom surface 7 and the gash bottom surface 12 of the chip discharge groove 4.

  Therefore, in such a second embodiment, the intersecting ridge line portion 14 between the bottom surface 7 of the chip discharge groove 4 and the gash bottom surface 12 is thus connected by the convex curved surface, so that it is generated by the bottom blade 10 and is inside the gash 8. When the chips that have flown into the chip are discharged into the chip discharge groove 4 on the outer peripheral side as indicated by white arrows in FIG. Compared with the case where it cross | intersects, it can prevent the situation where a chip | tip gets stuck in this intersection ridgeline part 14, and the discharge | emission is inhibited. For this reason, according to this embodiment, the chip | tip produced | generated by the bottom blade 10 can be promoted more smoothly and reliably, and the improvement of the chip | tip discharge | emission property can be aimed at.

  Also in this embodiment, the bottom blade rake face 9 constituting the gash 8 is bent in a convex shape with respect to the outer peripheral edge rake face 5 of the chip discharge groove 4. Like the first embodiment, the rake face 5 may intersect in a stepped manner with an obtuse angle at the intersecting ridge line portions 11, but similar to the intersecting ridge line portion 14 of the present embodiment. In addition, the intersecting ridge line portion 11 may have a convex curved surface having a convex curve in a cross section perpendicular to the cross ridge line portion 11, and the bottom surface 7 of the chip discharge groove 4 and the gash bottom surface 12 intersect at an angle at the intersecting ridge line portion 14. In this way, only the intersecting ridge line portion 11 may have a convex curved surface shape. Further, when at least one of the intersecting ridge line portions 11 and 14 is formed into a convex curved surface in this way, it is desirable that the convex curved surface be in smooth contact with both surfaces intersecting the intersecting ridge line portions 11 and 14, respectively. However, it may be formed so that it touches only one of the surfaces smoothly and intersects the other surface with a slight angle (obtuse angle) to leave a ridgeline, and also intersects both surfaces with an angle. It may be made to do.

  Next, in the third embodiment shown in FIG. 5, the gash bottom surface 12 of the gash 8 is a convex curved surface as in the first embodiment or a flat surface as in the second embodiment. Instead, it is characterized in that a part thereof is formed in an uneven shape as shown in FIG. Here, the gash bottom surface 12 has a direction from the inner peripheral side to the outer peripheral side of the end mill main body 1 as shown by a hollow arrow line in FIG. Thus, the surface is made uneven in the direction in which the chips are discharged into the chip discharge groove 4, and the inner peripheral side portion of the gash bottom surface 12 is uneven except for a small portion on the outer peripheral side. It has been made.

  Further, in FIG. 5, the irregularities formed by the gash bottom surface 12 have a corrugated shape in which the cross-section of the triangular saw blade-shaped peaks and valleys is smoothed into an irregular arc shape. The concave and convex shape of the cross-sectional waveform is formed over the entire groove width direction of the concave groove formed by the gash 8 between the concave and convex portions 13. For example, the concave and convex shape has a continuous sinusoidal curve or concave and convex arc. Other corrugated shapes may be used, and convex arc-shaped convex portions are formed on the flat surface at an interval or adjacent to each other, or conversely concave portions such as concave arc-shaped concaves from the flat surface on the flat surface. May be formed at intervals or adjacent to each other. Further, instead of making the gash bottom surface 12 uneven in the groove width direction of the gash 8 in this way, for example, a dot-shaped projection or recess such as a spherical shape is formed on the gash bottom surface 12 to form the gash bottom surface. 12 may be uneven.

  According to such 3rd Embodiment, the chip | tip produced | generated by the bottom blade 10 and having flowed in into the gash 8 from the bottom blade rake surface 9 is discharged | emitted to the outer peripheral side of the end mill main body 1, rubbing the gash bottom surface 12. In this case, the chips come into contact with only the convex top portions of the concave and convex gash bottom surface 12, and the contact area between the chips and the gash bottom surface 12 becomes small. Accordingly, the frictional resistance caused by the scraping of the gash bottom surface 12 is reduced, so that the scraping by the bottom blade 10 can be more reliably guided to the chip discharging groove 4 to improve the chip discharging performance, and smoother. In addition, stable cutting can be promoted.

  In the third embodiment, the gash bottom surface 12 has an irregular shape as described above, but the bottom blade rake surface 9 may be irregular, and both the bottom blade rake surface 9 and the gash bottom surface 12 are irregular. It is good also as a shape. Further, the irregularities formed on the bottom blade rake face 9 and the gash bottom surface 12 in this way are in the direction in which the chips generated as described above are scraped and discharged or flow out of the bottom blade rake face 9 and the gash bottom face 12. It is desirable that the surface of the chip be uneven, and the surface may be uneven in a direction parallel to the outflow direction of the chips, or may be uneven in a direction forming an angle with respect to the outflow direction. Further, by combining these second and third embodiments, for example, an intersecting ridge line portion 14 between the gash bottom surface 12 and the bottom surface 7 of the chip discharge groove 4 having the uneven shape of the third embodiment shown in FIG. As in the second embodiment shown in FIG.

  Furthermore, in these first to third embodiments, the case where the shank portion 2 on the rear end side of the end mill body 1 and the cutting edge portion 3 on the front end side are integrally formed as shown in FIG. However, the present invention is applied to an end mill in which the shank portion 2 and the cutting blade portion 3 are separated and the blade body having the cutting blade portion 3 as described above is detachably attached by a known attachment / detachment mechanism. May be. In this case, the cutting blade portion 3 may be formed by injection molding of a material such as cemented carbide, and the shank portion 2 may be manufactured by injection molding or other methods using the same material or different materials. . Further, in the above embodiment, the case where the end mill body 1 is manufactured by injection molding of a material such as cemented carbide has been described, but the above-described gash 8 is formed by a grindstone as in the end mill described in Patent Document 1. By doing so, the end mill of the said structure can also be manufactured.

1 is a perspective view showing a first embodiment of the present invention. In the embodiment shown in FIG. 1, a portion along the bottom surface 7 of the chip discharge groove 4 from the gash bottom surface 12 is cut by a twisted surface that passes through the axis O and is twisted in accordance with the twist of the chip discharge groove 4, thereby rotating the end mill. It is sectional drawing which expand | deployed the cross section seen from T on the plane. FIG. 3 is a cross-sectional view of a gash 8 portion along a ZZ cross section in FIG. 2 (however, the coolant hole 17 is omitted). It is sectional drawing equivalent to FIG. 2 of 1st Embodiment which shows the 2nd Embodiment of this invention (however, the coolant hole 17 is abbreviate | omitted). It is sectional drawing equivalent to FIG. 2 of 1st Embodiment which shows the 2nd Embodiment of this invention (however, the coolant hole 17 is abbreviate | omitted).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 End mill body 3 Cutting edge part 4 Chip discharge groove 5 Outer peripheral edge rake face 6 Outer peripheral edge 7 Bottom face of chip discharge groove 4 8 Gash 9 Bottom edge rake face 10 Bottom edge 11 Outer edge rake face 5 and bottom edge rake face 9 Intersecting ridgeline portion 12 Gash bottom surface 13 Gash wall surface 14 Intersecting ridgeline portion 15 between the gash bottom surface 12 and the bottom surface 7 of the chip discharge groove 4 15 Intersecting ridgeline portion between the bottom edge scoop surface 9 and the gash bottom surface 16 Gash bottom surface 12 and the gash wall surface 13 Crossing ridge line part 17 Coolant hole O Axis line of end mill body 1 T End mill rotation direction

Claims (5)

A chip discharge groove is formed on the outer periphery of the end portion of the end mill body rotated about the axis, and the surface of the chip discharge groove facing the end mill rotation direction is a peripheral edge scooping surface, and the peripheral blade is formed on the peripheral side ridge. In addition, a gash is formed in the open groove portion of the chip discharge groove on the tip end side of the end mill body, and a surface facing the end mill rotation direction of the gash is a bottom blade rake surface, and the tip of the bottom blade rake surface An end mill in which a bottom blade whose outer peripheral edge is continuous with the tip of the outer peripheral blade is formed on the side ridge, and the cross ridge line between the bottom blade scoop surface and the gasche bottom surface facing the end mill main body tip side of the gasche And at least one of the intersecting ridge line portions of the gasche bottom surface and the gasche wall surface facing the rear side in the end mill rotation direction of the gasche is directly in the direction in which the intersecting ridge line portion extends. The cross section is formed so as to form a concave curve, and the radius of curvature of the concave curve formed by the cross section of the intersecting ridge portion is larger on the outer peripheral side of the end mill body than on the inner peripheral side. End mill. The bottom edge rake face is formed to be bent convexly with respect to the outer peripheral edge rake face so that an axial rake angle of the bottom edge is smaller than an axial rake angle of the outer peripheral edge. 2. The end mill according to claim 1, wherein at least one of the gash bottom surface and the gash wall surface has a convex curved shape that curves from an inner peripheral side to an outer peripheral side of the end mill main body. The bottom edge rake face is formed to be bent in a convex shape with respect to the outer edge rake face so that the axial rake angle of the bottom edge is smaller than the axial rake angle of the outer edge edge. The intersecting ridge line portion between at least one of the blade rake face and the gash bottom surface and the outer peripheral blade rake face or the bottom surface of the chip discharge groove has a convex curved surface in which a cross section perpendicular to the direction in which the intersecting ridge line portion extends forms a convex curve. The end mill according to claim 1 or 2, wherein the end mill is characterized by the above. The end mill according to any one of claims 1 to 3, wherein at least a part of at least one of the bottom edge rake face and the gash bottom face is formed in an uneven shape. The end mill according to any one of claims 1 to 4, wherein a coolant hole is opened on the bottom surface of the gasche.

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