JP2019171515A - Form end mill - Google Patents

Abstract

To restrain an increase in cutting resistance and to disperse cutting load in forming a clearance groove in a crankpin.SOLUTION: A cutting edge 7 projecting to the tip side of an end mill body 1 is formed on a crossing ridge line between a rake surface 5 facing in an end mill rotation direction T of a chip discharging groove 4 formed on a tip outer periphery of the end mill body 1 which is rotated around the axis O and a flank 6 crossing the rake surface 5. The rake surface 5 is inclined to the opposite side of the end mill rotation direction T as it extends from the inner peripheral side of the end mill body 1 to the outer peripheral side in a cross section orthogonal to the axis O. A radial rake angle α which is a positive angle is imparted to an inner peripheral side of the cutting edge 7.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a general-purpose end mill in which a recess groove recessed on the inner peripheral side of a crank pin is formed at a connection portion of a crank pin in a crank shaft of an engine to a balance weight.

  As such an end mill, Patent Document 1 discloses an end mill for machining a bearing region of a crankshaft, which includes an end face and a base having a plurality of inserts designed for turning, and the plurality of inserts are provided on the end face. Or it is arrange | positioned in an end surface, and the some insert has what has at least 1 cutting edge which alternately contains an effective cutting area and a non-effective cutting area. On the outside of the substrate, so-called radial inserts are arranged and used to machine the curved structure, ie the relief groove.

Special table 2012-528727 gazette

  By the way, the end mill used to form the relief groove in the crank pin of such a crankshaft is mainly used in a machining form in which the entire length of the cutting edge is cut into the crank pin of the crankshaft which is a work material. Therefore, the cutting resistance and the cutting load are increased and vibration is likely to occur. For this reason, there exists a possibility that chipping and a chip | tip may arise in a cutting blade by vibration, or processing precision may be impaired.

  The present invention has been made in view of such a background. In particular, in a complete end mill used for forming a relief groove in a crank pin of a crankshaft as described above, an increase in cutting resistance and a cutting load are suppressed. It aims at providing the total form end mill which can aim at dispersion | distribution of this.

  In order to solve the above problems and achieve such an object, according to the present invention, a chip discharge groove extending from the front end of the end mill main body to the rear end side is provided on the outer periphery of the front end of the end mill main body rotated about the axis. A tip side of the end mill body is formed on a cross ridge line portion between a wall surface formed and facing the end mill rotation direction of the chip discharge groove and a rake face intersecting the rake face on the tip side of the end mill body. A cutting edge protruding to the end mill, and the rake face is inclined in the direction opposite to the end mill rotation direction from the inner peripheral side to the outer peripheral side of the end mill body in a cross section perpendicular to the axis. A positive radial rake angle is given to the inner peripheral portion of.

  In the general-purpose end mill configured as described above, a cutting blade that protrudes toward the tip end side of the end mill body is formed on the outer periphery of the tip end portion of the end mill body. A relief groove to which the shape of the cutting blade is transferred is formed to be recessed toward the inner peripheral side of the crank pin.

  Here, the rake face of the cutting edge is inclined in the direction opposite to the end mill rotation direction from the inner peripheral side to the outer peripheral side of the end mill main body in the cross section perpendicular to the axis, and therefore the cutting edge of the end mill main body is inclined. The crank blade is cut from the inclined blade on the inner peripheral side of the cutting edge on the inner peripheral side, and the rake face is inclined in this way, so that a positive radial rake angle is formed on the inner peripheral portion of the cutting edge. Is given.

  Accordingly, the inner peripheral portion of the cutting blade is gradually cut into the crankpin from the inclined blade, so that the sharpness of the inner peripheral portion of the cutting blade can be sharpened and the increase in cutting resistance is suppressed. In addition, the cutting load can be distributed, and chipping and chipping can be prevented from occurring on the cutting edge and processing accuracy can be prevented from being impaired.

  The rake face is inclined so as to be directed in the direction opposite to the end mill rotation direction while drawing a convex curve from the inner peripheral side to the outer peripheral side of the end mill body in a cross section perpendicular to the axis. As a result, it is possible to ensure a large blade angle in the inner peripheral portion of the steel plate and prevent chipping and chipping more reliably and improve chip separation and obtain good chip discharge performance.

  The rake face is drawn in a convex curve shape that is convex in the end mill rotation direction when viewed from the outer peripheral side of the end mill body, and toward the opposite side of the end mill rotation direction toward the rear end side of the end mill body. Even if formed so as to extend, the cutting edge can be given a positive axial rake angle to suppress cutting resistance and to distribute the cutting load, and more reliably prevent chipping and chipping of the cutting edge. And even better chip discharge performance can be obtained.

  Here, the cutting blade is in contact with the outer peripheral end of the inclined blade as viewed from the end mill rotation direction and extends toward the tip side from the inner peripheral side to the outer peripheral side of the end mill body, and from the end mill rotation direction. A radial direction with respect to the axial line of the inner peripheral portion of the cutting blade by including a convex curved blade that protrudes toward the rear end side and protrudes toward the rear end side as it goes toward the outer peripheral side of the end mill body. Can be made longer than the outer periphery of the cutting edge, and the range in which the radial rake angle becomes a positive angle can be increased, so that the increase in cutting resistance and the distribution of cutting load can be more reliably achieved. be able to.

  In this case, it is desirable that the inclination angle of the inclined blade with respect to the plane perpendicular to the axis as viewed from the end mill rotation direction is 30 ° or more. If the inclination angle is less than 30 °, in order to form a clearance groove having a necessary depth, the inclination blade must be lengthened, which may increase the cutting resistance.

  Furthermore, since no ridge line intersecting the cutting edge is formed on the rake face, it is possible to prevent chipping from occurring at the cutting edge starting from the intersection of such a ridge line and the cutting edge. Even if the rake angle in the radial direction of the inner peripheral portion of the cutting edge is a positive angle, stable cutting can be performed over a long period of time. Similarly, since the flank does not have a ridge line intersecting the cutting edge, the same effect can be obtained.

  Here, the fact that the ridge line intersecting the cutting edge is not formed on the rake face or the flank face is, for example, the maximum height roughness in JIS B0601: 2013 in the direction along the cutting edge of the rake face or the flank face. Rz is preferably less than 2.0 μm. If a step with such a maximum height roughness Rz in the direction of 2.0 μm or more is formed on the rake face or flank face, the ridge line can be visually confirmed, and the intersection of the ridge line and the cutting edge This increases the possibility of chipping.

  As described above, according to the present invention, since a positive radial rake angle is given to the inner peripheral portion of the cutting blade that is first cut into the crankpin, the inner peripheral portion of the cutting blade gradually becomes the crankpin. The cutting force can be suppressed, the increase in cutting resistance can be suppressed, the cutting load can be dispersed, and the chipping or chipping of the cutting edge can be prevented or the processing accuracy can be prevented from being impaired. Can do.

It is a perspective view which shows one Embodiment of this invention. It is a front view of embodiment shown in FIG. It is a side view of the front-end | tip part of embodiment shown in FIG. It is ZZ sectional drawing in FIG. It is a figure which shows the state which forms a relief groove in the connection part with the balance weight of the crankpin of a crankshaft by embodiment shown in FIG.

  FIGS. 1 to 4 show an embodiment of the present invention. FIG. 5 shows a relief groove G formed in a connection portion between a crankpin P of a crankshaft S and a balance weight W by a complete end mill of this embodiment. The state which forms is shown. In the present embodiment, the end mill body 1 is formed in a substantially cylindrical shape centering on the axis O with a hard material such as cemented carbide, and the rear end portion (upper portion in FIG. 1) is a cylindrical shank portion 2. At the same time, the tip (the lower part in FIG. 1) is the cutting edge 3.

  Such a general-purpose end mill has a shank portion 2 gripped by the spindle of the machine tool and rotated in the end mill rotation direction T around the axis O, and around the center line of a crank pin P (not shown) extending in the lateral direction in FIG. As shown by the arrow F in FIG. 5, the crankshaft S that is a work material to be rotated is fed to the front end side in the direction of the axis O, and is connected to the balance weight W of the crankpin P by the cutting edge portion 3. A relief groove G is formed.

  On the outer periphery of the cutting edge portion 3, a plurality of chips (four in this embodiment) are formed at intervals in the circumferential direction, and chip discharge grooves 4 extending from the front end of the end mill body 1 to the rear end side are formed. At the tip of the end mill body 1 at the crossing ridge line portion between the wall surface that is the rake face 5 facing the end mill rotation direction T of the discharge groove 4 and the flank face 6 that intersects the rake face 5 on the tip side of the end mill body 1. A protruding cutting edge 7 is formed. On the outer periphery of the distal end portion of the cutting blade portion 3, a protruding portion 8 that protrudes toward the distal end side of the end mill body 1 is formed, and the cutting blade 7 is formed on the protruding portion 8.

  In the present embodiment, the cutting blade 7 includes an inclined blade 7A that extends linearly toward the distal end side from the inner peripheral side to the outer peripheral side of the end mill body 1 when viewed from the end mill rotation direction T, and an outer periphery of the inclined blade 7A. A convex curve blade 7B having a convex curve shape such as an arc or the like that protrudes toward the front end side as it approaches the outer peripheral side of the end mill body 1 as viewed from the end mill rotation direction T and contacts the end and then toward the rear end side. The inclination angle θ with respect to the plane perpendicular to the axis O of the inclined blade 7A is set to 30 ° or more. The four cutting edges 7 formed at the tip of the four chip discharge grooves 4 have the same rotation trajectory around the axis O.

  As shown in FIG. 4, the rake face 5 is inclined to the side opposite to the end mill rotational direction T as it goes from the inner peripheral side to the outer peripheral side of the end mill main body 1, as shown in FIG. 4. The inner peripheral portion of the cutting blade 7 including the inclined blade 7A and the portion of the convex curved blade 7B that extends to the outer peripheral side of the end mill body 1 and continues to the outer peripheral side of the end mill main body 1 has a positive angle. A radial rake angle α is given.

  In addition, the rake face 5 draws a convex curve from the inner peripheral side to the outer peripheral side of the end mill body 1 in a cross section orthogonal to the axis O as shown in FIG. It is inclined to. Further, the length of the cutting edge 7 in the radial direction with respect to the axis O is such that the inner peripheral portion is closer to the outer peripheral portion than the outer peripheral portion (from the protruding end of the convex curved blade 7B toward the distal end side of the end mill body 1 toward the outer peripheral side. Longer than the part toward the rear end).

  Further, as shown in FIG. 3, the rake face 5 has a convex curve shape that is convex in the end mill rotation direction T even when viewed from the outer peripheral side of the end mill main body 1, and the end mill rotation direction T and Extends to the opposite side. Accordingly, the axial rake angle β of the cutting edge 7 is also a positive angle.

  Further, the rake face 5 is formed by a cross section perpendicular to the axis O and one convex curved surface swelled in the end mill rotation direction T that forms a convex curve when viewed from the outer peripheral side of the end mill body 1. In the embodiment, the ridge line intersecting the cutting edge 7 is not formed on the rake face 5. Similarly, the flank 6 is also formed as a flat surface in a range connected to the inclined blade 7A, and is formed as a convex curved surface in a range connected to the convex curve blade 7B. No ridge line intersecting 7 is formed.

  Here, the fact that the ridge line intersecting the cutting edge 7 is not formed on the rake face 5 or the flank face 6 as described above is, for example, the maximum height in JIS B0601: 2013 in the direction along the cutting edge of the rake face or flank face. The roughness Rz is less than 2.0 μm, which is 0.58 μm in the present embodiment. When the maximum height roughness Rz is 2.0 μm or more, such a ridge line can be confirmed by visual observation.

  The general-purpose end mill configured as described above is arranged so that the axis O is orthogonal to the center line of the crank pin P described above, and the cutting blade protrudes toward the front end side of the end mill body 1 that rotates in the tool rotation direction T. 7 is cut into a connection portion with a balance weight W of the crankpin P of the crankshaft S which is a work material, so that a clearance groove G in which the shape of the cutting blade 7 is transferred to the connection portion is formed in the crankpin P. It is formed so as to be recessed in the circumferential side. Since the crank pin P is cylindrical, when the cutting edge 7 is at a position other than the connecting portion, the crank pin P is separated from the outer peripheral side of the crank pin P and does not interfere with the crank pin P.

  The rake face 5 of the cutting edge 7 is inclined to the side opposite to the end mill rotation direction T as it goes from the inner peripheral side to the outer peripheral side of the end mill main body 1 in the cross section orthogonal to the axis O. Therefore, the cutting edge 7 Is cut into the crankpin P from the inner peripheral portion, and a positive radial rake angle α is given to the inner peripheral portion of the cutting blade 7 as described above.

  For this reason, the inner peripheral portion of the cutting blade 7 is gradually cut into the crank pin P from the inclined blade 7A on the inner peripheral side, so that the sharpness of the inner peripheral portion of the cutting blade 7 can be sharpened. Even when the entire cutting edge 7 is cut into the crank pin P, an increase in cutting resistance can be suppressed and the cutting load can be dispersed. Therefore, it is possible to prevent the cutting blade 7 from being chipped or chipped or from being damaged in processing accuracy.

  Further, in the present embodiment, the rake face 5 is inclined so as to be directed to the opposite side to the end mill rotation direction T while drawing a convex curve from the inner peripheral side to the outer peripheral side of the end mill body 1 in a cross section orthogonal to the axis O. It has been made. For this reason, since the cutter angle in the inner peripheral part of the cutting blade 7 can be ensured large, even if the radial rake angle α of the inner peripheral part of the cutting blade 7 is a positive angle, chipping and chipping of the cutting blade 7 are further reduced. It can be surely prevented. In addition, since the rake face 5 is formed in a convex curve shape in this way, the chip separation is improved, so that a good chip discharging property can be obtained.

  Further, in the present embodiment, the rake face 5 draws a convex curve shape that is convex in the end mill rotation direction T even when viewed from the outer peripheral side of the end mill body 1, and the end mill rotation direction as it goes toward the rear end side of the end mill body 1. The cutting edge 7 has an axial rake angle β that is a positive angle. For this reason, it is possible to further suppress the cutting resistance and promote the dispersion of the cutting load, to more reliably prevent chipping and chipping of the cutting edge 7, and to obtain better chip dischargeability.

  Furthermore, in this embodiment, the cutting blade 7 protruding toward the tip end side of the end mill main body 1 extends linearly toward the tip end side from the inner peripheral side to the outer peripheral side of the end mill main body 1 when viewed from the end mill rotation direction T. An inclined blade 7A and a convex curved convex shape such as an arc that touches the outer peripheral end of the inclined blade 7A and protrudes toward the distal end side toward the outer peripheral side of the end mill body 1 when viewed from the end mill rotation direction T and then toward the rear end side. And a curved blade 7B.

  Accordingly, the radial length with respect to the axis O of the inner peripheral portion of the cutting blade 7 can be made longer than the outer peripheral portion of the cutting blade 7, so that the radial rake angle α is a positive angle. Can be increased, and the increase in cutting force can be suppressed and the cutting load can be more reliably distributed.

  In this case, as in the present embodiment, it is desirable that the inclination angle θ with respect to the plane perpendicular to the axis O of the inclined blade 7A when viewed from the end mill rotation direction T is 30 ° or more, and thereby the necessary groove It is possible to prevent the inclined blade 7A from becoming too long to form the clearance groove G having a depth, and it is possible to reliably suppress an increase in cutting resistance. That is, if the inclination angle θ is less than 30 °, the inclined blade 7A must be lengthened in order to form a clearance groove having a required depth, and the cutting blade 7 is cut into the crank pin P. There is a possibility that the portion becomes long and the cutting resistance increases.

  Furthermore, even if the sharpness of the inner peripheral portion of the cutting edge 7 is sharpened as described above, in the total shape end mill of this embodiment, for example, JIS B0601: in the direction along the cutting edge 7 of the rake face 5 or the flank face 6. By making the maximum height roughness Rz in 2013 less than 2.0 μm or the like so that a ridge line intersecting the cutting edge 7 is not formed on the rake face 5 or the flank face 6, the sharp cutting edge 7 can be formed. A situation in which chipping occurs can be prevented more reliably.

  That is, if the ridge line intersecting the cutting edge 7 is formed on the rake face 5 or the flank face 6 in this way, chipping is likely to occur in the cutting edge 7 starting from the intersection of the ridge line and the cutting edge 7. In the present embodiment, since the ridge line forming such an intersection as the starting point is not formed on the rake face 5 or the flank face 6, the rake angle α in the radial direction of the inner peripheral portion of the cutting edge 7 is set to be a positive angle and sharpness is sharpened. Even so, such chipping can be prevented from occurring.

  In the present embodiment, it is assumed that the ridge line intersecting the cutting edge 7 is not formed on both the rake face 5 and the flank face 6, but one of the rake face 5 and the flank face 6 is on the cutting edge 7. The intersecting ridge lines may not be formed. However, in order to ensure chipping, it is preferable that the ridge line intersecting the cutting edge 7 is not formed on both the rake face 5 and the flank face 6 as in this embodiment.

DESCRIPTION OF SYMBOLS 1 End mill body 3 Cutting edge part 4 Chip discharge groove 5 Rake face 6 Relief face 7 Cutting edge 7A Inclined blade 7B Convex curve edge 8 Protrusion O End mill body 1 axis T End mill rotation direction θ End mill rotation direction T Inclination angle α with respect to a plane perpendicular to the axis O of the inclined blade 7A Radial rake angle of the inner periphery of the cutting blade 7

Claims (7)

A chip discharge groove extending from the front end of the end mill main body to the rear end is formed on the outer periphery of the front end of the end mill main body rotated around the axis.
The chip discharge groove protrudes toward the front end side of the end mill body at a crossing ridge line portion between a wall surface facing the end mill rotation direction and a rake face and a flank surface intersecting the rake face on the front end side of the end mill body. A cutting edge is formed,
The rake face is inclined to the side opposite to the end mill rotation direction from the inner peripheral side of the end mill body to the outer peripheral side in a cross section orthogonal to the axis, and a positive angle is formed on the inner peripheral part of the cutting edge. A complete end mill characterized by a rake angle in the radial direction.   The rake face is inclined so as to be directed to the opposite side to the end mill rotation direction while drawing a convex curve from the inner peripheral side to the outer peripheral side of the end mill body in a cross section orthogonal to the axis. The complete end mill according to claim 1.   The rake face extends in a direction opposite to the end mill rotation direction toward the rear end side of the end mill body while drawing a convex curve shape that is convex in the end mill rotation direction when viewed from the outer peripheral side of the end mill body. The total type end mill according to claim 1 or 2, characterized by comprising:   The cutting blade is in contact with the outer peripheral end of the inclined blade and extends from the inner peripheral side of the end mill body toward the outer peripheral side as viewed from the end mill rotational direction, and the outer peripheral end of the inclined blade, and is viewed from the end mill rotational direction. 4. A convex curved blade that protrudes toward the front end side toward the outer end side of the end mill main body and then toward the rear end side is provided. 5. Total shape end mill as described.   5. The complete end mill according to claim 4, wherein an inclination angle of the inclined blade with respect to a plane perpendicular to the axis when viewed from the end mill rotation direction is 30 ° or more.   6. The complete end mill according to claim 1, wherein a ridge line intersecting the cutting edge is not formed on the rake face.   The ridge line which intersects the said cutting edge is not formed in the said flank, The complete | finished end mill as described in any one of Claims 1-6 characterized by the above-mentioned.

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