JP2009078346A - End mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an end mill supplying an adequate amount of cutting oil without degrading rigidity of the end mill body, extending the tool life, and performing cutting work with high machining accuracy. <P>SOLUTION: In the end mill, a cutting oil supply passage 23 is bored extending from a rear end toward the end of the end mill body 10 along an axis line O, a plurality of cutting oil distribution passages 24 are bored branching from the cutting oil supply passage 23 and opened to respective chip discharge grooves 14, and a branched part 25 where the cutting oil distribution passages 24 and the cutting oil supply passage 23 communicate with each other is displaced in the direction of the axis line O. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In the present invention, a plurality of chip discharge grooves are formed on the outer periphery of the end portion of the end mill body rotated about the axis, and a cutting edge is formed on the outer peripheral side ridge portion of the wall surface facing the end mill rotation direction, and cutting is performed. The present invention relates to an end mill in which a cutting oil supply passage for supplying oil is formed in the end mill body.

  The end mill is generally formed in a columnar shape and a chip discharge groove is formed on the outer periphery of the end portion of the end mill body that is rotated around its axis, and the outer peripheral side ridge portion of the wall surface that faces the front side in the end mill rotation direction of the chip discharge groove The cutting edge is formed on the top edge and the bottom edge connected to the tip of the cutting edge is formed on the side edge of the tip, which is used to cut the workpiece such as grooving and shouldering. It is done. Here, the chip discharge groove is usually formed in a spiral shape twisted around the axis so as to go to the rear side in the end mill rotation direction toward the rear end side of the end mill body, and thus the rotation direction of such a chip discharge groove The cutting edge formed on the outer peripheral side ridge portion of the wall surface facing toward is also formed by being twisted so as to go to the rear side in the rotation direction toward the rear end side of the end mill body.

  Some end mills include an oil hole for supplying cutting oil having a lubricating effect and a cooling effect to the cutting edge in order to reduce friction during cutting and to remove processing heat (for example, Patent Documents). 1, see Patent Document 2). As a result, the tool life can be extended, the machining accuracy can be secured, and good cutting can be performed.

An example of an end mill having such oil holes is shown in FIG. The oil hole in the end mill branches from the cutting oil supply path 2 formed along the axis O of the end mill body 1 from the rear end side to the front end side of the end mill main body 1 and the cutting oil supply path 2. The end mill main body 1 is composed of a plurality of cutting oil distribution passages 3 that open to a chip discharge groove 4 formed on the outer periphery of the tip portion. The branch portion 5 that is one end of each cutting oil distribution path 3 and communicates with the cutting oil supply path 2 is formed so as to open at the same position in the axis O direction with respect to the peripheral surface of the cutting oil supply path 2. ing.
JP-A-5-253727 JP-A-6-335815

  By the way, since the torsional stress is received by the cutting resistance and the rotational driving force at the time of cutting by the end mill, the end mill main body 1 needs to have rigidity sufficient to withstand this torsional stress. However, in the end mill having the above oil hole, the branching portion 5 is formed so as to open at the same position with respect to the circumferential surface of the cutting oil supply passage 2 in the direction of the axis O. The cross-sectional area of the end mill main body 1 in a vertical cross section is reduced by the presence of each cutting oil distribution path 3, and the rigidity is lowered. As a result, there is a problem that the end mill main body is easily damaged from this position due to torsional stress, the life of the end mill main body 1 is shortened, and the processing cost is increased.

  In addition, since this problem becomes more prominent as the number of cutting oil distribution paths 3 increases, the number of cutting oil distribution paths 3 cannot be increased in order to ensure the rigidity of the end mill body 1. In some cases, sufficient cutting oil cannot be supplied. This also shortens the life of the end mill main body 1 and may reduce the processing accuracy.

  The present invention has been made in view of such a problem, and can supply a sufficient amount of cutting oil without reducing the rigidity of the end mill body, thereby extending the tool life and improving the machining accuracy. An object of the present invention is to provide an end mill that can be cut at a high height.

In order to solve the above problems, the present invention proposes the following means.
That is, in the end mill according to the present invention, a plurality of chip discharge grooves that spirally twist around the axis are formed on the outer periphery of the end portion of the end mill main body that rotates about the axis, and these chip discharge grooves are forward in the end mill rotation direction. In an end mill in which a cutting edge is formed on the outer peripheral side ridge portion of the wall surface facing the side, a cutting oil supply path extending along the axis is drilled from the rear end side of the end mill body toward the front end side. In addition, a plurality of cutting oil distribution passages that are branched from the cutting oil supply passage and open to the chip discharge grooves are formed, and the branching portion where the cutting oil distribution passage and the cutting oil supply passage communicate with each other Is provided by being shifted in the axial direction.

  According to the end mill having such a configuration, the branch portion that is one end of the cutting oil distribution passage and communicates with the cutting oil supply passage is provided so as to be shifted in the axial direction without overlapping in the axial direction. At the position of the portion, it is possible to suppress a reduction in the cross-sectional area in the cross section perpendicular to the axis line due to the presence of each cutting oil distribution path, and an end mill having a long tool life that is rigid and is not easily damaged. In addition, since the rigidity is ensured in this way, the number of cutting oil distribution paths can be increased, so that more cutting oil can be supplied and the tool life of the end mill can be further extended. In addition, the processing accuracy can be improved.

  The end mill according to the present invention is characterized in that a plurality of the cutting oil distribution passages are opened in each of the chip discharge grooves.

  Since the reduction in rigidity of the end mill body due to the presence of the cutting oil distribution path is suppressed, sufficient rigidity can be secured even if multiple cutting oil distribution paths are provided in the chip discharge groove, and more cutting oil is supplied. It becomes possible to do.

  Further, in the end mill according to the present invention, the intersection of the virtual cylindrical surface having the lead length of the cutting edge as L, the outer diameter dimension as D, and the outer diameter dimension D as a diameter and the virtual extension line of the cutting oil distribution passage. When the interval in the axial direction is b, the interval a in the circumferential direction of the intersection on the virtual cylindrical surface is set to a = πD × (b / L).

  By providing a plurality of cutting oil supply passages in this way, the distance in the cross section perpendicular to the axis of each of the openings in the chip discharge groove of the cutting oil supply passage and the cutting blade can be made constant. It becomes possible to supply cutting oil effectively in the whole area.

  Further, in the end mill according to the present invention, at least two of the plurality of chip discharge grooves have the cutting oil distribution passage in which the branch portion is provided shifted in the axial direction, and the position in the axial direction is the same. It may be opened so as to be.

As a result, while ensuring the rigidity in the vicinity of the cutting oil supply passage as described above, the supply distribution of the cutting oil of the cutting blades facing in the circumferential direction can be made the same. In the same manner, uniform cutting can be performed.
Further, for example, in an end mill having three or more blades, only the cutting oil distribution passages in at least two chip discharge grooves are opened so that the positions in the axial direction are the same. By making the supply distribution of cutting oil the same as other chip discharge grooves, but avoiding the cutting oil distribution path from concentrating and opening at the same position in the axial direction, the rigidity at the outer periphery of the end mill body is more than necessary. It can prevent that it falls.

  According to the end mill of the present invention, a sufficient amount of cutting oil is supplied without reducing the rigidity of the end mill main body by providing the oil hole branching portion shifted in the axial direction without overlapping the axial direction. Therefore, it is possible to extend the tool life of the end mill and to perform cutting with high machining accuracy.

  Hereinafter, a first embodiment of an end mill according to the present invention will be described with reference to FIGS. 1 to 4. 1 is a side view in which a part of an end mill according to the first embodiment is broken, FIG. 2 is a front sectional view showing the arrangement of oil holes of the end mill according to the first embodiment, and FIG. 3 is a first embodiment. FIG. 4 is a development view of the shank portion and the virtual cylindrical surface of the end mill main body according to the first embodiment.

  In the first embodiment, as shown in FIGS. 1 and 2, the end mill main body 10 is formed of a hard material such as a cemented carbide and is formed integrally with a hard material so as to be centered on the axis O and extend along the axis O. The rear end portion (right side portion in FIG. 1) is a shank portion 12, and the tip end portion (left side portion in FIG. 1) is a cutting edge portion 13. A plurality of (two in the present embodiment) circumferential direction of chip discharge grooves 14 spirally twisted toward the rear side in the end mill rotation direction T when cutting about the axis O from the front end to the rear end side of the end mill body 10. Are formed at equal intervals.

  The wall surface 15 of the chip discharge groove 14 facing the front side in the end mill rotation direction T is formed in a concave curved surface in a cross section orthogonal to the axis O as shown in FIG. A cutting edge 17 that is spirally twisted at the same twist angle as that of the chip discharge groove 14 is formed at the intersecting ridge line portion with the outer peripheral surface 16 of the cutting edge portion 13. It is considered a surface.

  Further, on the outer peripheral surface 16, in order from the cutting edge 17 toward the rear side in the end mill rotation direction T, a flank 18 connected to the cutting edge 17, a flank 18 connected to the flank 18, and a clearance angle and An outer peripheral flank 19 having a large circumferential width is formed. In addition, a margin that extends from the cutting edge 17 to the rear side in the end mill rotation direction T may be provided. In addition, the outer peripheral surface 16 on the rear side in the end mill rotational direction T from the outer peripheral flank 19 retreats one step toward the inner peripheral side with respect to the outer peripheral flank 19 and then draws a convex curved surface toward the rear side in the end mill rotational direction T. Further, it is formed so as to continue to the wall surface 15 which is the rake face of the cutting blade 17 through the chip discharge groove 14.

  On the other hand, as shown in FIG. 1, a gash 20 is formed at the tip of the chip discharge groove 14. The gash 20 is a recess formed so as to radially cut out the tip edge of the wall surface 15 of the chip discharge groove 14 from the center of the tip of the end mill body 1 to the outer peripheral flank 9 on the outer periphery of the tip. In this embodiment, the wall surface facing the end mill rotation direction T is a planar gash surface 11 that is substantially parallel to the axis O. A bottom blade 21 is formed at the intersecting ridge line portion between the gash surface 11 and the tip flank 12 formed at the tip of the end mill body 10 so as to continue to the tip of the cutting blade 17.

  The end mill body 10 has a cutting oil supply passage 23 formed therein and supplied with cutting oil, and a plurality of branches extending from the cutting oil supply passage 23 and extending linearly and opening into the chip discharge groove 14. An oil hole 22 including a cutting oil distribution path 24 is formed.

  The cutting oil supply path 23 is formed as a bottomed hole that extends along the axis O toward the front end side while opening to the rear end side of the shank portion 12. In the present embodiment, the shape of the cutting oil supply path 23 is formed as a circular cross section having a constant diameter centered on the axis O over the entire length, and the inner diameter is the outer diameter, thickness, etc. of the end mill body 10. Can be set in consideration.

  On the other hand, each cutting oil distribution path 24 opens to the inner peripheral surface of the cutting oil supply path 23 as a branching portion 25 that communicates with the cutting oil supply path 23 on one end side of the inner periphery, and the chip discharge groove 14 on the other end side. A discharge port 26 is formed by opening the bottom surface of the groove portion toward the cutting edge. In the present embodiment, the cutting oil distribution path 24 is formed so that two discharge ports 26 are opened to the two chip discharge grooves 14, that is, four are branched from the cutting oil supply path 23. ing.

  These cutting oil distribution passages 24 are formed in a circular cross section having a constant diameter from the branching portion 25 to the discharge port 26, and more specifically, as shown in FIG. As it goes to the outer peripheral side, it is inclined so as to extend linearly toward the tip side. And the branch part 25 of each cutting-oil distribution path 24 is shifted and provided so that the position of the axis line O direction may not mutually overlap.

  Note that the cutting oil distribution path 24 is not limited to the one that is inclined so as to extend toward the tool tip side toward the outer peripheral side as described above, but extends vertically from the cutting oil supply path 23 toward the outer peripheral side. There may be.

  Further, as shown in detail in FIGS. 2 and 4, the arrangement of the discharge ports 26 that are openings of the respective cutting oil distribution paths 24 is such that the chip discharge grooves 14 and the cutting blades 17 that are twisted in a spiral shape are arranged around the axis O. A virtual cylindrical surface P and a cutting oil distribution path 24 having a lead length which is a length in the direction of the axis O during one round as L, an outer diameter dimension of the cutting edge 17 as D, and an outer diameter dimension of the cutting edge 17 as a diameter When an interval R (corresponding to the discharge hole 26) of the intersection R with the virtual extension line Q in the direction of the axis O is b, the circumferential interval a on the virtual cylindrical surface P of the intersection R is a = πD × ( b / L). Thereby, the distance of the circumferential direction in the cross section perpendicular | vertical to the axis line O of the two discharge ports 26 and the cutting blade 17 in each chip discharge groove 14 is made constant.

  In the end mill configured as described above, the shank portion 12 formed at the rear end of the end mill body 10 is gripped by the spindle end of the machine tool, rotated around the axis O, and in a direction intersecting the axis O. Is sent to the workpiece to groove it. At this time, the cutting oil is supplied to the outer peripheral surface 16 of the chip discharge groove 14 via the cutting oil supply path 23 and the cutting oil distribution path 24, and reaches the cutting edge 17. Reduces friction with the machine and removes processing heat.

  During cutting with such an end mill, the end mill body 10 needs to have rigidity sufficient to withstand this torsional stress because it receives a torsional stress due to cutting resistance and rotational driving force. According to the end mill having the above-described configuration, the branch portion 25 in the oil hole 22 is provided so as to be shifted in the axis O direction without overlapping in the axis O direction. The reduction of the cross-sectional area in the cross section perpendicular to the cross section can be suppressed, the rigidity of the end mill body 10 is ensured, and the life of the end mill body 10 can be extended.

  In addition, since the rigidity is ensured in this way, the number of the cutting oil distribution passages 24 can be increased. Therefore, a plurality (two in this embodiment) are provided for each chip discharge groove 14 as in the present embodiment. The strength of the end mill body 10 can be maintained even if the cutting oil distribution passage 24 is formed so as to open. Therefore, more cutting oil can be supplied, and the tool life of the end mill can be further extended by the lubricating effect and cooling effect of the cutting oil, and the machining accuracy can be improved.

  Furthermore, in the end mill according to the present embodiment, the circumferential distance in the cross section perpendicular to the axis O between the two discharge ports 26 and the cutting blade 17 in each chip discharge groove 14 is constant. It becomes possible to supply cutting oil effectively in the whole area of 17, and the lubricating effect and cooling effect by the cutting oil can be obtained more effectively.

  As described above, according to the end mill of the present embodiment, the branch portion 25 in the oil hole 22 is provided in a shifted manner in the direction of the axis O without overlapping in the direction of the axis O. An appropriate amount of cutting oil can be supplied, the tool life of the end mill can be extended, and cutting can be performed with high processing accuracy.

  In the end mill, two chip discharge grooves 14 are formed on the outer periphery of the end portion of the end mill main body 10, and a cutting edge is formed on the outer side edge of the wall surface facing the front side in the end mill rotation direction T of the chip discharge grooves 14. In the two-blade end mill in which 17 is formed, two cutting oil discharge ports 26 are provided for one chip discharge groove 14, but the present invention is not limited to this. For example, FIG. The present invention may be applied to a six-blade end mill 30 as in the modification shown, and three or more cutting oil discharge ports 26 may be provided for one chip discharge groove 14. Also in this case, a branch portion (not shown) that is one end of a cutting oil distribution (not shown) that communicates with the discharge port 26 and communicates with the cutting oil supply passage 23 is shifted in the direction of the axis O without overlapping in the direction of the axis O. Since it is provided, the rigidity of the end mill is ensured.

  Next, a second embodiment of the end mill according to the present invention will be described with reference to FIGS. FIG. 6 is a longitudinal sectional view showing the arrangement of the oil holes of the end mill according to the second embodiment, and FIG. 7 is a development view of the shank portion and the virtual cylindrical surface of the end mill body of the second embodiment.

The end mill of this embodiment is a two-blade end mill similar to that of the first embodiment, and the discharge ports 26 in the chip discharge grooves 14 facing in the circumferential direction are on the same circumference around the axis O. It is different from the first embodiment in that it is arranged, and the other configuration is the same as that of the first embodiment.
6 and 7 showing the second embodiment, the same components as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

As shown in FIG. 6, the four cutting oil distribution passages 28 in the second embodiment are linearly formed at the same inclination angle with respect to the axis O when the ones opened in the same chip discharge groove 14 are compared. It extends. On the other hand, when the openings in the chip discharge grooves 14 facing each other in the circumferential direction are compared, the inclination angles with respect to the axis O are different from each other.
As a result, the branch portion 25 communicating with the cutting oil supply passage 23 is disposed so that the positions in the direction of the axis O do not overlap with each other, while the discharge port 26 in the chip discharge groove 14 is formed as shown in FIGS. As shown in FIG. 5, the chip discharge grooves 14 facing each other are arranged so as to be located on the same circumference around the axis O, that is, in the same direction in the direction of the axis O.

Also in the present embodiment, as in the first embodiment, the arrangement of the discharge ports 26 that are the openings of the respective cutting oil distribution passages 28 is such that the lead length is L and the cutting edge 17 is arranged as shown in FIG. The distance in the direction of the axis O between the intersection R (corresponding to the discharge hole 26) of the virtual cylindrical surface P having the outer diameter dimension D and the outer diameter dimension of the cutting edge 17 and the virtual extension line Q of the cutting oil distribution path 28. Is set so that the interval a in the circumferential direction on the virtual cylindrical surface P of the intersection R is a = πD × (b / L).
Thereby, the distance of the circumferential direction in the cross section perpendicular | vertical to the axis O of the two discharge ports 26 and the cutting blade 17 in each chip discharge groove 14 is made constant. Further, in the present embodiment, unlike the first embodiment, the intersection R in the facing chip discharge groove 14 is also arranged on the same circumference around the axis O in accordance with the arrangement of the discharge ports 26.

  According to the end mill of the second embodiment configured as described above, as in the end mill of the first embodiment, the discharge in the two chip discharge grooves 14 is ensured while ensuring the rigidity in the vicinity of the cutting oil supply passage 23. Since the outlet 26 is located on the same circumference centering on the axis O, the supply distribution of the cutting oil to each chip discharge groove 14 can be made the same. Therefore, uniform cutting can be performed with the same lubricating effect and cooling effect for each of the cutting edges 17 formed on the outer peripheral side ridges of the chip discharge grooves 14.

  The end mill according to the second embodiment is not limited to the two-blade end mill shown in FIGS. 6 and 7, and may be a four-blade end mill as shown in a development view of FIG. 8 as a modification. In this end mill, out of the four chip discharge grooves 14, the discharge ports 26 in the pair of chip discharge grooves 14 facing in the circumferential direction (the virtual cylindrical surface P in FIG. 8 and the virtual extension line Q of the cutting oil distribution passage 24 in FIG. 8). (Corresponding to the intersection R) are arranged on the same circumference centered on the axis O, that is, arranged at the same position in the direction of the axis O, and a pair of chip discharge grooves 14 facing each other in the circumferential direction (a pair) ) Are disposed at the same position at different positions in the axis O direction.

  Thereby, in the chip discharge grooves 14 opposed in the circumferential direction, the same lubrication effect and cooling effect can be obtained by making the supply distribution of the cutting oil the same, while in the chip discharge grooves 14 adjacent in the circumferential direction, Since the positions of the discharge holes 26 are shifted and dispersed in the direction of the axis O, it is possible to prevent the rigidity of the outer periphery of the end mill body 10 from being lowered more than necessary.

As mentioned above, although the embodiment of the end mill which is this invention was described in detail, unless it deviates from the technical idea of this invention, it is not limited to these, A some design change etc. are possible.
For example, the two-blade and six-blade end mills are shown in the first embodiment, and the two-blade and four-blade end mills are shown in the second embodiment. However, the present invention is not limited to these. In both embodiments, the end mill may be provided with a number of cutting blades 17 other than the above.

It is the side view which fractured a part of end mill concerning a first embodiment. It is front sectional drawing which shows arrangement | positioning of the oil hole of the end mill which concerns on 1st embodiment. It is a longitudinal cross-sectional view which shows arrangement | positioning of the oil hole of the end mill which concerns on 1st embodiment. It is an expanded view of the shank part and virtual cylindrical surface of an end mill main body in 1st embodiment. It is a side view of the end mill of the modification of 1st embodiment. It is a longitudinal cross-sectional view which shows arrangement | positioning of the oil hole of the end mill which concerns on 2nd embodiment. It is an expanded view of the shank part and virtual cylindrical surface of an end mill main body in 2nd embodiment. It is an expanded view of the shank part and virtual cylindrical surface of the end mill main body of the modification of 2nd embodiment. It is a side view of the conventional end mill.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 End mill main body 14 Chip discharge groove 15 Wall surface 17 Cutting edge 23 Cutting oil supply path 24 Cutting oil distribution path 25 Branch part 26 Discharge port 28 Cutting oil distribution path O Axis line P Virtual cylindrical surface Q Virtual extension line R Virtual cylindrical surface and virtual extension Intersection with line T End mill rotation direction

Claims (4)

A plurality of chip discharge grooves spirally twisted around the axis are formed on the outer periphery of the end portion of the end mill body rotated around the axis, and the outer peripheral side ridges of the wall surface facing the front side in the end mill rotation direction of these chip discharge grooves In the end mill where the cutting edge is formed in the part,
A cutting oil supply path extending along the axis is formed from the rear end side to the front end side of the end mill body, and branches from the cutting oil supply path and opens into the chip discharge grooves. Multiple cutting oil distribution passages are drilled,
An end mill characterized in that a branch portion where the cutting oil distribution path and the cutting oil supply path communicate with each other is provided by being shifted in the axial direction.   The end mill according to claim 1, wherein a plurality of the cutting oil distribution passages are opened in each of the chip discharge grooves. The lead length of the cutting edge is L, the outer diameter dimension is D, and the axial distance between the intersections of the virtual cylindrical surface having the outer diameter dimension as a diameter and the virtual extension line of the cutting oil distribution path is b. When
The end mill according to claim 2, wherein a distance a in the circumferential direction of the intersection on the virtual cylindrical surface is set to a = πD × (b / L).   In at least two of the plurality of chip discharge grooves, the cutting oil distribution path provided with the branch portions shifted in the axial direction is opened so that the positions in the axial direction are the same. The end mill according to any one of claims 1 to 3, wherein the end mill is characterized.

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