JP2013202748A - End mill - Google Patents

Abstract

An object of the present invention is to provide a chip discharge groove on the rear end side of an end mill main body formed with at least one outer peripheral blade whose twist angle is smaller than that of an outer peripheral blade adjacent to the front side in the end mill rotation direction when used in longitudinal feed processing. Ensure chip discharge.
SOLUTION: A plurality of chip discharge grooves 4 extending toward the rear end side are formed on the outer periphery of the front end portion of the end mill body 1 rotated about the axis O, and the outer peripheral side of the wall surface facing the end mill rotation direction T An outer peripheral blade 5 is formed at each ridge, and a bottom blade extending from the distal end of these outer peripheral blades 5 to the inner peripheral side is formed at the end portion of the end mill body 1, and at least one outer peripheral blade 5A is located on the front side in the end mill rotation direction T. The twist angle with respect to the axis O is made smaller than that of the outer peripheral blade 5B adjacent to the outer peripheral blade 5B, and the at least one chip discharge groove 4A in which the outer peripheral blade 5A is formed has a diameter d of a thick circle centering on the axis O in contact with the groove bottom surface. However, it becomes small as it goes to the end mill main body 1 rear end side.
[Selection] Figure 4

Description

  In the present invention, a plurality of chip discharge grooves extending from the front end of the end mill body toward the rear end side are formed on the outer periphery of the end portion of the end mill main body rotated about the axis, and the end mill rotation direction of these chip discharge grooves is determined. The present invention relates to an end mill in which outer peripheral blades are respectively formed on outer peripheral side ridges of the facing wall surface, and bottom blades extending from the front ends of these outer peripheral blades to the inner peripheral side are formed at the front end portion of the end mill body.

  As such an end mill, Patent Document 1 discloses at least one outer periphery among a plurality of outer peripheral blades (cutting blades) formed on the outer peripheral side ridge portion of the wall surface facing the end mill rotation direction of the plurality of chip discharge grooves. The blade has a smaller distance from the outer peripheral blade adjacent to the front side in the end mill rotation direction than the other outer peripheral blades, and at least one of the outer peripheral blades is formed on the outer peripheral side edge of the wall surface facing the end mill rotation direction. At least one chip discharge groove has a diameter of a core thick circle in contact with the groove bottom surface larger than a diameter of a core thick circle of a chip discharge groove on which other outer peripheral blades are formed, that is, a groove depth is shallow. Has been proposed.

  According to such an end mill described in Patent Document 1, the amount of chips generated is small in the at least one outer peripheral blade whose distance from the outer peripheral blade adjacent to the front side in the end mill rotation direction is smaller than the other outer peripheral blades. The rigidity and strength of the outer peripheral blade can be improved while ensuring a sufficient capacity in the chip discharge groove for discharging. Further, in Patent Document 1, in order to make the interval between the at least one outer peripheral blade adjacent to the front side in the end mill rotation direction smaller than the other outer peripheral blades, the axis of the at least one outer peripheral blade The twist angle is smaller than that of the outer peripheral blade adjacent to the front side in the end mill rotation direction, and the outer peripheral blades are equally spaced in the circumferential direction at the front end and rear end of the outer peripheral blade or between the front and rear ends. It is also described that it is not evenly spaced at any position.

JP 2007-136627 A

  By the way, in recent years, in such an end mill, the end mill body is fed in the axial direction in addition to the normal machining in which the end mill body is fed in the direction intersecting the axis and shouldering or grooving is performed on the work material. The material is increasingly used for longitudinal feed processing in which a hole is formed in a material with a bottom blade, and then the end mill body is fed in a direction intersecting the axis to form a pocket.

  However, when used in such vertical feed processing, as described in Patent Document 1, the twist angle is made smaller than that of the outer peripheral blade adjacent to the front side in the end mill rotation direction, and Chips in which a chip discharge groove formed with at least one outer peripheral blade whose interval is made smaller as it goes toward the rear end side of the end mill body has a diameter of a thick circle in contact with the bottom surface of the groove is formed with another outer peripheral blade If the groove depth is made shallower than the diameter of the core thick circle of the discharge groove, chips generated on the front end side of the end mill body during vertical feed processing may cause clogging on the rear end side. is there.

  In particular, as described in Patent Document 1, when the circumferential interval of the outer peripheral blade is equal at the position between the rear end of the outer peripheral blade and the front end and the rear end, at least 1 with a small twist angle. The bottom blades connected to the tips of the two outer peripheral blades have a larger distance in the circumferential direction from the bottom blade adjacent to the front side in the end mill rotation direction than the other bottom blades, and the amount of chips generated is also increased. Moreover, in the end mill described in Patent Document 1, the bottom blade connected to the tip of the at least one outer peripheral blade extends toward the inner peripheral side of the end mill body beyond the position of the axis of the end mill main body. Therefore, the amount of chips generated is larger than that of other bottom blades, and there is a higher risk of chip clogging, and the resistance increases and a large amount of driving force is required to rotate the end mill body. Alternatively, the processed surface of the work material may be damaged by clogged chips, leading to deterioration of the roughness of the processed surface and deterioration of the processed quality.

  The present invention has been made under such a background, and is used for vertical feed machining even if the twist angle of at least one outer peripheral blade is smaller than that of the outer peripheral blade adjacent to the front side in the end mill rotation direction. It is an object of the present invention to provide an end mill capable of ensuring chip discharge performance on the rear end side of the end mill body of the chip discharge groove in which the at least one outer peripheral blade is formed.

  In order to solve the above problems and achieve such an object, the present invention provides a plurality of strips extending from the front end of the end mill body toward the rear end side on the outer periphery of the front end of the end mill body rotated about the axis. Chip discharge grooves are formed, outer peripheral blades are respectively formed on the outer peripheral side ridges of the wall surfaces facing the end mill rotation direction of these chip discharge grooves, and the tip ends of the outer peripheral blades are provided at the tip of the end mill body. A bottom blade extending to the inner peripheral side of the end mill body is formed, and at least one of the outer peripheral blades has a smaller twist angle with respect to the axis than the outer peripheral blade adjacent to the front side in the end mill rotation direction. And at least one chip discharge groove formed on the outer peripheral side ridge portion of the wall surface in which the at least one outer peripheral blade faces the end mill rotation direction is in contact with the groove bottom surface. The diameter of the heart Atsuen around the said axis, characterized in that it is set smaller toward the end mill body rear side.

  Therefore, in the end mill configured as described above, at least one outer peripheral blade has a twist angle smaller than that of the outer peripheral blade adjacent to the front side in the end mill rotation direction, and the circumferential interval between these outer peripheral blades is the rear end of the end mill body. Even if it becomes smaller as it goes toward the end side, the diameter of the core circle that contacts the groove bottom surface becomes smaller as the at least one chip discharge groove on which the at least one outer peripheral blade is formed goes toward the rear end side of the end mill body. Since the groove depth becomes deep, a capacity for chip discharge on the rear end side of the end mill body can be secured in the at least one chip discharge groove.

  For this reason, when used in the vertical feed processing as described above, even if the bottom blade connected to the tip of the at least one outer peripheral blade is spaced from the bottom blade adjacent to the front side in the end mill rotation direction, the other bottom Even when it is made larger than the blade, or it is a long bottom blade extending beyond the position of the axis of the end mill body tip toward the inner peripheral side of the end mill body, or both of them, It is possible to prevent clogging of the at least one chip discharge groove, and it is possible to prevent an increase in rotational driving force of the end mill body and a reduction in roughness and quality of the processed surface due to such clogging. On the other hand, the other chip discharge groove formed on the outer peripheral side ridge portion of the wall surface in which the other outer peripheral blades other than the at least one outer peripheral blade face the end mill rotation direction has a groove width toward the rear end side of the end mill body. As it becomes constant or wide, there is no chip clogging.

  In addition, the other chip discharge groove formed on the outer peripheral side ridge portion of the wall surface where the outer peripheral blade other than the at least one outer peripheral blade faces the end mill rotation direction is directed toward the rear end side of the end mill body as described above. Since the groove width is constant or widened and the capacity for chip discharge does not decrease, the diameter of the core thickness circle around the axis contacting the groove bottom surface of the other chip discharge groove is determined in the axial direction. In this case, it is possible to suppress a reduction in rigidity of the end mill body due to a decrease in the diameter of the core thickness circle of at least one chip discharge groove on the rear end side of the end mill body while maintaining chip discharge performance. .

  In addition, the plurality of chip discharge grooves, in particular, as described above, by making the diameters of the thick circles centered on the axis line in contact with the groove bottom surface equal to each other on the tip side of the end mill body. The bottom blade connected to the tip of at least one outer peripheral blade has a larger distance from the bottom blade adjacent to the front side in the end mill rotation direction than the other bottom blade, or a long bottom blade. Even if the amount of generated chips is large and a large cutting load is applied, the same strength and rigidity as those of other bottom blades can be secured and stable machining can be performed.

  As described above, according to the present invention, it is possible to prevent clogging of chips on the rear end side of the end mill body of the chip discharge groove in which at least one outer peripheral blade having a reduced twist angle is formed. It is possible to prevent an increase in the rotational driving force of the end mill main body and a decrease in the roughness of the machined surface due to chip clogging, and to perform efficient and high-quality cutting.

It is a perspective view which shows one Embodiment of this invention. It is a side view of embodiment shown in FIG. It is an enlarged front view of embodiment shown in FIG. FIG. 3 is a ZZ enlarged sectional view in FIG. 2. It is an expanded view of the outer periphery blade of embodiment shown in FIG. It is a figure which shows the change with respect to the distance from the front-end | tip of an outer peripheral blade of the ratio which the diameter of the core thick circle which contact | connects the bottom face of the chip discharge groove | channel of embodiment shown in FIG. 1 makes with respect to the outer diameter of an outer peripheral blade (FIG. 6). The right side of the horizontal axis is the rear end side of the end mill body.)

  1 to 6 show an embodiment of the present invention. In this embodiment, the end mill body 1 has a substantially cylindrical shaft shape centered on the axis O with a hard material such as cemented carbide, and the rear end portion (the upper portion in FIGS. 1 and 2) remains a cylindrical shank. The tip 2 (the lower part in FIGS. 1 and 2) is the cutting edge 3, and the shank 2 is gripped by the spindle of the machine tool and rotates in the end mill rotation direction T about the axis O. In general, the workpiece is fed in a direction intersecting the axis O, and the workpiece is cut by the cutting edge portion 3.

  A plurality of (three in the present embodiment) chip discharge grooves 4 are circumferentially spaced around the outer periphery of the cutting edge 3 at the tip of the end mill body 1, and the axis extends from the tip of the cutting edge 3 toward the rear end. It is formed so as to be twisted to the rear side in the end mill rotation direction T around O, and this wall surface is used as a rake face at the outer peripheral side edge of the wall surface facing the end mill rotation direction T side of the chip discharge grooves 4. The same number of outer peripheral blades 5 as the chip discharge grooves 4 rotate the end mill around the axis O from the tip 3 of the end mill body 1 toward the rear end as in the case of the chip discharge grooves 4. It is formed so as to be twisted to the rear side in the direction T. Here, the plurality of outer peripheral blades 5 are configured such that the rotation locus around the axis O forms one cylindrical surface centered on the axis O.

  Further, at the front end portions of the plurality of chip discharge grooves 4, gashes 6 are formed so as to further cut out the inner peripheral portions of these chip discharge grooves 4 inward, and the end mill rotation direction T of these gashes 6 A bottom blade 7 extending from the tip of the outer peripheral blade 5 to the inner peripheral side is formed on the front edge of the wall surface facing the side, with the wall surface as a rake face. Here, the end mill of this embodiment is a square end mill in which the bottom blade 7 intersects the tip of the outer peripheral blade 5 at an outer peripheral end thereof at an angle of 90 ° or slightly smaller than 90 ° as shown in FIG. However, for example, a radius end mill in which the outer peripheral blade 5 and the bottom blade 7 are connected via a corner blade having a convex curve such as a substantially ¼ arc, It is also possible to apply the present invention to a ball end mill having a hemispherical shape centered on O.

  In the present embodiment, as shown in FIG. 3, one bottom blade 7 among the plurality (three) of the bottom blades 7 formed in the same number as the chip discharge grooves 4 is formed from the tip of the outer peripheral blade 5 to the inner periphery. A long bottom blade 7A extending beyond the position of the axis O at the tip of the cutting edge 3 toward the side, and the remaining bottom blade 7 is a short having an inner peripheral end at a position away from the axis O toward the outer peripheral side. The bottom blade 7B is used. Further, the interval between the bottom blades 7 in the circumferential direction is the interval from the long bottom blade 7A to the short bottom blade 7B located on the front side in the end mill rotation direction T, and the interval from the remaining short bottom blade 7B to the end mill rotation direction T. It is made larger than the space | interval to the bottom blade 7 located in the front side.

  Therefore, by setting the distance between the bottom blades 7 in this way, the distance between the tips of the outer peripheral blades 5 is also the outer peripheral blade 5 connected to the long bottom blade 7A and the outer peripheral blade 5 adjacent to the front side in the end mill rotation direction T. Is made larger than the distance between the remaining outer peripheral blade 5 connected to the short bottom blade 7B and the outer peripheral blade 5 adjacent to the front side in the end mill rotation direction T. In the present embodiment, at least one of the outer peripheral blades 5 connected to the long bottom blade 7A having a large interval from the outer peripheral blade 5 adjacent to the front side in the end mill rotation direction T has a smaller twist angle θ with respect to the axis O in the present embodiment. The outer peripheral blade 5A is connected to the remaining short bottom blade 7B, and the other outer peripheral blade 5B is used.

  And among the several chip discharge grooves 4, at least 1 chip discharge groove 4A formed in the outer peripheral side ridge part of the wall surface in which the said at least 1 outer peripheral blade 7A faces the end mill rotation direction T is as shown in FIG. On the rear end side of the end mill body 1 of the cutting edge 3, the diameter d of the core circle with the axis O in contact with the groove bottom as the center is the groove of the other chip discharge groove 4 </ b> B in which the other outer peripheral edge 5 </ b> B is formed. The diameter D is smaller than the diameter D of the thick core circle centering on the axis O in contact with the bottom surface.

  The diameter d of the core thickness circle in the at least one chip discharge groove 4 is equal to the diameter D of the core thickness circle of the other chip discharge groove 4B on the front end side of the end mill body 1 as shown in FIG. It is made to become small gradually as it goes to the side. Furthermore, as shown in FIG. 6, the diameters D and d of these core thick circles are the outer diameters of the outer peripheral blades 5 (the rotation trajectory of the outer peripheral blades 5) even on the rear end side of the at least one chip discharge groove 4A. Is 50% or more of the diameter of the cylindrical surface).

  In addition, the twist angle θ of at least one outer peripheral blade 5A is made smaller than that of the other outer peripheral blades 5B, so that at least one chip discharge groove 4A in which the at least one outer peripheral blade 5A is formed As shown in FIG. 4, the width gradually decreases toward the rear end side of the end mill body 1. Therefore, as shown in FIG. 5, the circumferential interval between at least one outer peripheral blade 5A and the other outer peripheral blade 5B adjacent to the front side in the end mill rotation direction T is also gradually reduced. In this embodiment, the cutting blade portion 3 On the rear end side, the distance between the other outer peripheral blade 5B and the outer peripheral blade 5 adjacent to the front side in the end mill rotation direction T is smaller than the circumferential interval.

  Further, in the present embodiment, as shown in FIG. 6, the other chip discharge groove 4 </ b> B formed on the outer peripheral side ridge portion of the wall surface in which the other outer peripheral blade 5 </ b> B faces the end mill rotation direction T is in contact with the groove bottom surface. The diameter D of the thick core around the axis O is constant along the axis O direction. Note that the twist angles of these other outer peripheral blades 5B may be equal to or different from each other as long as they are larger than the twist angle θ of at least one outer peripheral blade 5A.

  In the end mill having such a configuration, the circumferential direction of at least one outer peripheral blade 5A and the other outer peripheral blade 5B adjacent to the front side in the end mill rotation direction T as it goes toward the rear end side of the cutting blade portion 3 as described above. In particular, in this embodiment, at least one outer peripheral blade 5A is formed, although the distance between the other outer peripheral blades 5B and the outer peripheral blade 5 on the front side in the end mill rotation direction T is smaller than the distance between them. The diameter d of the core thick circle with which the groove bottom surface of at least one chip discharge groove 4A contacts is made smaller than the diameter D of the core thick circle with which the groove bottom surface of the other chip discharge groove 4B formed with the other outer peripheral blade 5B contacts. Therefore, the capacity of the at least one chip discharge groove 4 </ b> A can be ensured also on the rear end side of the cutting blade portion 3.

  Therefore, in the case of the longitudinal feed processing for feeding the end mill main body 1 in the direction of the axis O other than the processing for feeding in the direction intersecting the normal axis O, at least one outer peripheral blade 5A as in the present embodiment. The bottom blade 7 connected to the tip of the blade is a long bottom blade 7A extending beyond the position of the axis O at the tip of the cutting blade portion 3, and the short bottom blade is located on the front side in the end mill rotation direction T from the long bottom blade 7A. Even if the space | interval to 7B is made larger than the space | interval from the remaining short bottom blade 7B to the bottom blade 7 located in the end mill rotation direction T front side, even if more chips are produced | generated than these short bottom blades 7B. It is possible to prevent chip clogging from occurring in the at least one chip discharge groove 4A. For this reason, resistance increases due to such chip clogging and a larger driving force is required to rotate the end mill body 1, or the processed surface is damaged by the clogged chips, resulting in processed surface roughness and processed surface quality. Can be prevented, and efficient and highly accurate cutting can be performed.

  Further, another chip discharge groove 4 </ b> B in which another outer peripheral blade 5 that does not have a smaller twist angle with respect to the axis O than the outer peripheral blade 5 adjacent to the front side in the end mill rotation direction T is formed on the rear end mill body 1. Since the groove width increases toward the end side or remains constant, the capacity for chip discharge does not decrease. For this reason, as in this embodiment, the diameter D of the core thick circle in contact with the bottom surface of the other chip discharge groove 4B is constant, and the center of the at least one chip discharge groove 4A on the rear end side of the end mill body 1 is used. Even if the diameter is larger than the diameter d of the thick circle, chip clogging does not occur, and a decrease in the rigidity of the cutting edge portion 3 can be suppressed by reducing the diameter d of the core thick circle.

  Further, in the present embodiment, the core thick circles of the plurality of chip discharge grooves 4 have the same diameters D and d on the tip side of the end mill body 1. However, in particular, the bottom blade 7 connected to the tip of the at least one outer peripheral blade 5A whose twist angle θ is smaller than that of the other outer peripheral blade 5B as in this embodiment is a long bottom blade 7A, and its end mill When the distance to the bottom blade 7 located on the front side in the rotation direction T is larger than that of the remaining short bottom blade 7B and the amount of chips generated is large, the long bottom blade 7A is formed into the vertical direction to the bottom blade 7. Although the cutting load at the time of feed processing also increases, the diameter d of the core thickness circle of the at least one chip discharge groove 4A on which the at least one outer peripheral blade 5A is formed is different on the tip side of the end mill body 1 in this way. Since the same as the diameter D of the core thickness circle of the chip discharge groove 4B, the strength and rigidity equivalent to those of the short bottom blade 7B can be ensured also for the long bottom blade 7A. Even if the cutting load on the long bottom blade 7A is large, it is safe. Processing it is possible to perform that.

  The position of the tip end side of the end mill main body 1 where the diameters D and d of the core thickness circles of the plurality of chip discharge grooves 4 are made equal to each other in this way is, for example, the position of the tip of the outer peripheral blade 5 as shown in FIG. Also good. In this case, when the gash 6 is formed and the groove bottom surface of the tip of the chip discharge groove 4 is notched as in the present embodiment, the groove bottom of the portion where the gash 6 is not formed is used as the end mill body 1. It is only necessary that the diameters D and d of the core thick circle in contact with the bottom surface of the virtual groove extending toward the tip end be equal at the tip of the outer peripheral blade 5. Further, at the positions where the diameters D and d of the core thick circles of the plurality of chip discharge grooves 4 are equal to each other, the gash 6 on the rear end side of the end mill body 1 is slightly formed from the front end of the outer peripheral blade 5. It may be a position.

  Moreover, although the said embodiment demonstrated the case where the outer periphery blade 5 was applied to three end mills, the outer periphery blade can also be applied to two end mills or four or more end mills. For example, when the outer peripheral blade 5 is applied to four end mills, at least one outer peripheral blade 5A having a smaller twist angle θ than the outer peripheral blade 5 adjacent to the front side in the end mill rotation direction T, and the at least one outer peripheral blade 5A. What is necessary is just to form other outer peripheral blades 5B other than in the circumferential direction alternately.

DESCRIPTION OF SYMBOLS 1 End mill main body 3 Cutting edge part 4, 4A, 4B Chip discharge groove 5, 5A, 5B Outer peripheral blade 6 Gash 7 Bottom blade 7A Long bottom blade 7B Short bottom blade O End mill main body 1 axis T End mill rotation direction θ Outer blade 5A Twist angle D, d Diameter of the core thick circle in contact with the bottom surface of the chip discharge groove 4

Claims (5)

  A plurality of chip discharge grooves extending from the front end of the end mill body toward the rear end side are formed on the outer periphery of the end portion of the end mill body rotated about the axis, and the wall surfaces of the chip discharge grooves facing the end mill rotation direction are formed. An outer peripheral blade is formed on each of the outer peripheral side ridges, and a bottom blade extending from the distal end of the outer peripheral blade to the inner peripheral side of the end mill main body is formed at the distal end of the end mill body. The at least one outer peripheral edge of the wall surface has a smaller twist angle with respect to the axis than the outer peripheral edge adjacent to the front side in the end mill rotation direction, and the at least one outer peripheral edge of the wall surface faces the end mill rotation direction. The at least one chip discharge groove formed in the ridge portion has a diameter of a core circle centered on the axis line in contact with the bottom surface of the groove toward the rear end side of the end mill body. End mill, characterized in that Unishitagai are smaller in.   Other chip discharge grooves formed on the outer peripheral side ridge portion of the wall surface in which the outer peripheral blade other than the at least one outer peripheral blade faces the end mill rotation direction is a core thickness circle centered on the axis line in contact with the groove bottom surface. The end mill according to claim 1, wherein a diameter of the end mill is constant over the axial direction.   3. The diameter of the core thick circle centering on the axis line in contact with the groove bottom surface of the plurality of chip discharge grooves is equal to each other on the tip end side of the end mill body. The described end mill.   The said bottom blade connected with the front-end | tip of the said at least 1 outer peripheral blade has the space | interval with the bottom blade adjacent to the front side in the end mill rotation direction larger than the other bottom blades. The end mill according to any one of Items 3.   The bottom blade connected to the tip of the at least one outer peripheral blade is a long bottom blade extending toward the inner peripheral side of the end mill body beyond the position of the axis of the end mill body tip. The end mill according to any one of claims 1 to 4.

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