JP2013208655A - End mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an end mill which can divide swarf even when the end mill is used in finish processing.SOLUTION: An end mill is formed with outer peripheral cutting edges extending in an axial direction in an outer periphery of a tip of an end mill body that is rotated about an axis. At least a part of at least one of the outer peripheral cutting edges is subjected to honing, and has a part that is changed so that a honing amount of the honing is increased and then decreased or decreased and then increased toward a rear end side in the axial direction.

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 main body rotated about an axis.

  As such an end mill, in Patent Document 1, honing is applied to the cutting edge (outer peripheral blade) formed on the outer periphery of the end portion of the end mill body, and the amount of honing is increased from the front side to the rear side in the end mill rotation direction. There has been proposed one that changes in the axial direction so as to become smaller or larger. In such an end mill, the fracture resistance of the outer peripheral blade can be improved in the portion where the honing amount is increased, while the sharpness can be sharpened in the portion where the honing amount is reduced.

JP 2009-045704 A

  By the way, the outer peripheral blade of such an end mill is generally formed in a spiral shape that is twisted around the axis of the end mill body, and chips are removed by gradually cutting into the work material from one end in the axial direction. When the cutting edge length in the axial direction of the outer peripheral blade is long or when the axial rake angle (twisting angle) is large, the chip becomes longer, and the biting of the chip and clogging of the chip occur. May occur. However, in rough machining, it is possible to divide the chips by making the outer peripheral edge into a wavy edge or nicking the outer peripheral edge, but such means cannot be used in finishing.

  The present invention has been made under such a background, and an object thereof is to provide an end mill capable of dividing chips even when used for finishing.

  In order to solve the above problems and achieve such an object, the present invention provides an end mill in which an outer peripheral blade extending in the axial direction is formed on the outer periphery of a tip end portion of an end mill body rotated about an axis. At least some of the two outer peripheral blades are honed, and the honing amount of the honing is decreased after increasing or increased after decreasing toward the axial rear end side. , Characterized by having a changed part.

  In the end mill configured in this manner, the honing amount of honing applied to at least a part of the at least one outer peripheral blade decreases after increasing toward the rear end in the axial direction, or conversely increases. In the portion where the honing amount is large, the shear angle by the outer peripheral blade is smaller than that in the small portion, and the chips flow out in the forward direction. Accordingly, it is possible to divide the chips so that the chips generated at the portion where the honing amount is small and the shear angle is large are pulled by the chips flowing out in the previous direction.

  For this reason, when the cutting edge length in the axial direction of the outer peripheral blade is long or when the axial rake angle (twisting angle) is large, the outer peripheral blade does not need to be wavy or nicked. Chip biting and chip clogging can be prevented, and the increase in end mill rotational driving force due to chip biting and chip clogging can be prevented while smoothing the surface roughness even when used for finishing. Can be.

  Further, when a plurality of outer peripheral blades are formed at intervals in the circumferential direction on the end mill body, the honing amount of honing applied to at least two of the outer peripheral blades is directed toward the rear end side in the axial direction. Thus, if the portion where the honing amount of one outer peripheral blade is increased has a portion where the honing amount of the other outer peripheral blade is decreased, the shear angle of at least two outer peripheral blades is different in these portions. The resistance acting on the outer peripheral blade during chip generation can also be of different magnitude. Therefore, vibrations induced from the outer peripheral blade to the end mill main body due to such resistances have different frequencies and cancel each other, so that chatter vibrations can be prevented from occurring in the end mill main body.

  In addition, if the change of the honing amount is periodic, in particular, there are three or more outer peripheral blades formed on the outer periphery of the end portion of the end mill body, and among these, the honing amount of at least one outer peripheral blade increases. When honing so as to have a portion where the honing amount of the outer peripheral blade is reduced, the period of change of the honing amount is equal between the outer peripheral blades, and the phase is shifted in the axial direction. An end mill capable of preventing chatter vibration relatively easily can be obtained. The honing may be chamfer honing or composite honing, but is preferably round honing in which the honing amount can be changed relatively easily and accurately.

  As described above, according to the present invention, it is possible to divide chips without forming the outer peripheral edge into a wavy edge or attaching a nick, while forming a smooth finished surface for finishing. It is possible to reduce the rotational driving force of the end mill body by preventing chip biting and chip clogging.

It is a side view which shows one Embodiment of this invention. It is an AA expanded sectional view and CC expanded sectional view in FIG. It is BB expanded sectional drawing in FIG. It is DD expanded sectional drawing in FIG. One embodiment and other embodiments of the present invention, and the relationship between the distance from the tip of the outer peripheral blade of the conventional general end mill and the end mill described in Patent Document 1 to the rear end side in the axial direction and the honing amount It is a figure which shows an example.

  1 to 5 show an embodiment of the present invention. In the present embodiment, the end mill main 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 (upper portion in FIG. 1) is a cylindrical shank portion 2. At the same time, the tip portion (the lower portion in FIG. 1) is a cutting edge portion 3, and the shank portion 2 is gripped by the main spindle of the machine tool and rotated in the end mill rotation direction T around the axis O. The workpiece is fed in a direction intersecting with, and the work material is cut by the cutting edge portion 3.

  A plurality of (four in this 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 O extends from the tip of the cutting edge 3 toward the rear end. The chip discharge groove 4 is formed so as to be twisted around the rear side in the end mill rotation direction T around the outer peripheral edge of the wall surface facing the end mill rotation direction T side of the chip discharge groove 4. The same number of outer peripheral blades 5 are formed to be twisted to the rear side in the end mill rotation direction T around the axis O as it goes from the front end of the cutting blade portion 3 toward the rear end side, similarly to the chip discharge groove 4.

  Further, a gash 6 is formed at the tip of the chip discharge groove 4 so as to cut out the inner peripheral part of the chip discharge groove 4 further inward, and the wall surface of the gash 6 facing the end mill rotation direction T side. A bottom blade 7 having the wall surface as a rake face is formed at the leading edge of the. Here, as shown in FIG. 1, the end mill of the present embodiment is a square end mill in which the bottom blade 7 intersects with the tip of the outer peripheral blade 5 at the outer peripheral end thereof at an angle of 90 ° or slightly smaller than 90 °. 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.

  Then, honing 8 is applied to at least a part of at least one of the plurality of outer peripheral blades 5, and the honing amount of the honing 8 increases toward the rear end side in the axis O direction. It has a portion that has been changed to decrease later or increase after decreasing. Here, in the present embodiment, the honing 8 is a round honing as shown in FIGS. 2 to 4, and the honing amount is a radius of the honing (round honing) 8 of the outer peripheral blade 5 in a cross section orthogonal to the axis O. .

  Further, in the present embodiment, honing 8 is applied over the entire length of the outer peripheral blade 5, and the change in the honing amount changes from the tip of the outer peripheral blade 5 in the direction of the axis O as shown by reference numeral A in FIG. 5. As it goes to the rear end side, it continuously becomes larger and then becomes smaller and becomes equal to the honing amount at the tip, and then becomes smaller and then becomes larger again and becomes equal to the honing amount at the leading end, and the honing amount is maximized again. The cycle of increasing toward the honing amount is repeated constantly.

  Here, in this embodiment, the period is a sinusoidal smooth uneven curve as shown in FIG. 5 in the relationship between the distance from the front end of the outer peripheral blade 5 to the rear end side in the axis O direction and the honing amount. I am doing. In FIG. 5, symbol E indicates a case where the general honing amount does not change, and symbol F indicates that the honing amount described in Patent Document 1 increases toward the rear side in the end mill rotation direction. This is when it grows.

  Furthermore, in this embodiment, honing 8 is applied to at least two outer peripheral blades 5 among the plurality of outer peripheral blades 5, and the honing amount of the honing 8 applied to these outer peripheral blades 5 is the rear end in the axis O direction. The portion where the honing amount of the one outer peripheral blade 5 increases toward the side has a portion where the honing amount of the other outer peripheral blade 5 decreases. Here, in this embodiment, between the two outer peripheral blades 5 adjacent to each other in the circumferential direction, a portion where the honing amount of one outer peripheral blade 5 increases and a portion where the honing amount of the other outer peripheral blade 5 decreases. Has been.

  Specifically, assuming that the change in the honing amount of one outer peripheral blade 5 is indicated by the symbol A in FIG. 5, the change in the honing amount of the other outer peripheral blade 5 is, for example, as indicated by the reference symbol B in FIG. In addition, the maximum honing amount equal to the maximum honing amount of the one outer peripheral blade 5 at the tip of the other outer peripheral blade 5 is continuously reduced toward the rear end side in the axis O direction, and one outer peripheral blade 5 At the position in the axis O direction where the honing amount becomes the maximum, the honing amount at the tip of one outer peripheral blade 5 becomes equal.

  Furthermore, the honing amount of the other outer peripheral blade 5 becomes smaller toward the rear end side, and when the honing amount of one outer peripheral blade 5 becomes equal to the honing amount of the front end, the minimum honing amount of one outer peripheral blade 5 is obtained. The honing amount then increases toward the rear end side, and the honing amount at the tip of one outer peripheral blade 5 is the position in the axis O direction where the honing amount of one outer peripheral blade 5 is the minimum. It is made equal to the amount, and is further increased toward the maximum honing amount at the tip of the other outer peripheral blade 5. That is, the period of change of the honing amount made by the other outer peripheral edge 5 is such that the phase of the change period of the honing amount of one outer peripheral edge 5 is shifted to the tip side by 1/4 period.

  Of the four outer peripheral blades 5, the remaining two outer peripheral blades 5 may alternately repeat the period of change in the honing amount of the one outer peripheral blade 5 and the other outer peripheral blade 5, The phase of the change period of the honing amount of one outer peripheral blade 5 may be shifted to the tip side by 2/4 period and 3/4 period. Furthermore, the change period of the honing amount of the four outer peripheral blades 5 may be alternately repeated with the phase shifted by 1/2 period.

  In the end mill configured as described above, the honing amount is changed in the outer peripheral blade 5 which is changed so as to decrease after increasing the honing amount toward the rear end side in the axis O direction, or conversely, to increase after decreasing. Since the shear angle by the outer peripheral blade 5 is smaller with respect to the smaller portion when the portion is large, the chips generated from the honing 8 at the tip of the outer peripheral blade 5 are inclined more toward the end mill rotation direction T side, and the honing amount is small. Compared to the previous generation.

  Therefore, the chips generated by the small honing amount adjacent to the tip side or the rear end side or both sides thereof in the direction of the axis O are pulled by the chips generated by the portion having the large honing amount in this way, Chips can be divided at portions where the amount of honing is small. For this reason, when the working cutting edge length in the direction of the axis O of the outer peripheral blade 5 is long, or the axial rake angle (twisting angle) of the outer peripheral blade 5 twisted spirally is large, the working cutting edge along the outer peripheral blade 5 Even when the length is long, it is possible to prevent chipping and clogging of chips without making the outer peripheral blade 5 into a wave-blade luffing shape or nicking the outer peripheral blade 5. A smooth machined surface can be formed even during finishing, while preventing an increase in the rotational driving force of the end mill body 1 due to dents and chip clogging.

  In the present embodiment, the end mill body 1 is formed with a plurality of outer peripheral blades 5, and the honing amount of the two outer peripheral blades 5 among them is toward the rear end side in the axis O direction. The portion where the honing amount increases is provided with a portion where the honing amount of the other outer peripheral blade 5 decreases. Therefore, in the portion where the honing amount of one outer peripheral blade 5 increases in the direction of the axis O and the honing amount of the other outer peripheral blade 5 decreases, the resistance when the outer peripheral blade 5 bites the work material is reduced. One outer peripheral blade 5 and the other outer peripheral blade 5 have different sizes.

  Since the vibrations induced in the end mill body 1 by this resistance also have different frequencies, such vibrations having different frequencies can be canceled with each other, and chatter vibrations caused by resonance due to the coincidence of vibration frequencies can be prevented. Thus, smooth and highly accurate cutting can be performed. In particular, in the present embodiment, between the peripheral blades 5 adjacent to each other in the circumferential direction, the portion where the honing amount of the one outer peripheral blade 5 is increased has the portion where the honing amount of the other outer peripheral blade 5 is decreased. The vibrations can be canceled by the peripheral blades 5 that continuously bite the work material, and the effect of preventing chatter vibration is high.

  Furthermore, in the present embodiment, the change in the honing amount of the outer peripheral blade 5 is made periodic, and the honing 8 applied to at least two outer peripheral blades 5 among the plurality of outer peripheral blades 5 as described above When the portion where the honing amount of the outer peripheral blade 5 increases has a portion where the honing amount of the other outer peripheral blade 5 decreases, the period of change of this honing amount is equal between the one and the other outer peripheral blade 5. Thus, the phase is shifted in the axial direction.

  Therefore, the period of change of the honing amount is different, and the magnitude of the resistance is larger compared to the case where the honing amount is partially equal and the portions where the honing amount increases and decreases toward the rear end side overlap in the direction of the axis O. It is possible to prevent chatter vibrations relatively easily, but more reliably, by preventing the tendency of changes toward the sheath toward the rear end side.

  In addition, the honing 8 may be chamfer honing or composite honing in which the corners of the chamfer honing are rounded. In this case, the honing amount is equal to the width of the honing surface of the honing 8 in the cross section orthogonal to the axis O. However, in the present embodiment, the honing 8 is a round honing, and the honing amount can be changed relatively easily and more accurately. In particular, as shown in FIG. It is suitable when the change toward the rear end side in the O direction is continuous with a smooth uneven curve.

  In this embodiment, the relationship between the distance from the front end of the outer peripheral blade 5 to the rear end side in the axis O direction and the honing amount of the honing 8 in the outer peripheral blade 5 is smooth unevenness like a sine wave. The curve is continuous, and the rate of change of the honing amount is also changed over the entire length of the outer peripheral blade 5, but this relationship is shown in FIG. The rate is constant in a predetermined range, and a portion that is changed so as to decrease after the honing amount increases toward the rear end side in the axis O direction or to increase after the decrease is formed is formed. It may be. In addition, as indicated by D in FIG. 5, the honing 8 may have a constant portion without changing the honing amount over the entire length of the outer peripheral blade 5, and the honing amount is 0 and the honing 8 is applied. There may be parts that are not.

DESCRIPTION OF SYMBOLS 1 End mill main body 2 Shank part 3 Cutting blade part 4 Chip discharge groove 5 Outer peripheral blade 6 Gash 7 Bottom blade 8 Honing O Axis line of end mill main body 1 End mill rotation direction

Claims (4)

  In the end mill in which the outer peripheral blade extending in the axial direction is formed on the outer periphery of the end portion of the end mill body rotated around the axis, at least a part of at least one of the outer peripheral blades is honed. An end mill characterized in that it has a portion that is changed so that the amount decreases after increasing or increases after decreasing toward the axial rear end side.   The end mill body has a plurality of outer peripheral blades formed at intervals in the circumferential direction, and the honing amount of the honing applied to at least two of the outer peripheral blades is on the rear end side in the axial direction. The end mill according to claim 1, further comprising: a portion where the honing amount of one outer peripheral blade increases, and a portion where the honing amount of the other outer peripheral blade decreases.   The end mill according to claim 1 or 2, wherein the change in the honing amount is periodic.   The end mill according to any one of claims 1 to 3, wherein the honing is round honing.

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