JP2014184507A - End mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an end mill capable of adjusting a back taper of an outer peripheral cutting edge even material of a material to be cut or a cutting condition is different.SOLUTION: An outer peripheral cutting edge 5 is formed on a tip end part outer periphery of an end mill body 1 formed into a columnar shape in contour having an axis line O as a center. On a tip end part inner periphery of the end mill body 1, an adjustment hole 8 is formed along the axis line O, and into the adjustment hole 8, an adjustment member 10 for adjusting a back taper of the outer peripheral cutting edge 5 is inserted in a state that its outer peripheral face can slide contact to the inner peripheral face of the adjustment hole 8.

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 having an outer cylindrical shape centering on an axis.

  In such an end mill, Patent Document 1 describes a so-called back tapered square end mill in which the outer diameter of the outer peripheral blade is gradually reduced from the front end of the end mill body toward the rear end side. . According to such an end mill with a back taper, for example, when a recess having a bottom surface and a wall surface perpendicular to each other is formed on the work material by shoulder cutting, the tip portion on which the outer peripheral edge is formed is the work material. It is possible to prevent the end mill body from being tilted by coming into contact with the surface, so that the wall surface is formed obliquely so as to protrude toward the bottom surface side.

JP 2007-245278 A

  However, such an end mill with a back taper is usually a solid end mill in which the end mill body is integrally formed of a hard material such as cemented carbide or high-speed tool steel, and the back taper given to the outer peripheral blade is also 1 There is only one type of end mill body. For this reason, if the end mill body tilts differently depending on the material of the work material, cutting conditions, etc., it is possible to sufficiently suppress the protrusion of the wall surface unless cutting is performed with a back taper end mill corresponding to this. There was a possibility that the wall could not be formed, or conversely, the wall surface was formed to recede toward the bottom side.

  For example, when shoulder milling is performed by an end mill that is not provided with a back taper on the outer peripheral blade, or when the end mill main body falls down even if a back taper is provided, As shown in FIG. 6A, the wall surface A formed on the work material W is inclined so as to protrude from the surface perpendicular to the bottom surface B indicated by the broken line toward the bottom surface B. In addition, when shoulder milling is performed with an end mill having a back taper on the outer peripheral blade, if the tilt of the end mill body is smaller than the back taper, the wall surface A is also indicated by a broken line as shown in FIG. As compared with a surface perpendicular to the bottom surface, the surface is inclined so as to recede toward the bottom surface B side.

  The present invention has been made under such a background, and an end mill capable of adjusting the back taper of the outer peripheral blade according to the material, cutting conditions and the like of the work material are different. The purpose is to provide.

  In order to solve the above problems and achieve such an object, according to the present invention, an outer peripheral blade is formed on the outer periphery of the end portion of the end mill body having an outer cylindrical shape centering on the axis, An adjustment hole is formed in the circumference along the axis, and an adjustment member that adjusts the back taper of the outer peripheral blade can be slidably contacted with the inner peripheral surface of the adjustment hole in the adjustment hole. It is inserted.

  In the end mill configured as described above, the outer diameter of the adjusting member is slightly smaller than the inner diameter of the adjusting hole at the position where the outer peripheral surface of the adjusting member inserted into the adjusting hole is in sliding contact with the inner peripheral surface of the adjusting hole. By forming the end mill body so as to be large, the tip end portion of the end mill main body formed into a cylindrical shape with the adjustment hole is deformed so that the slidable contact position is slightly expanded in diameter. Therefore, by adjusting the back taper amount of the outer peripheral blade by increasing the diameter of the tip according to the end mill body falling due to the material of the work material, cutting conditions, etc., the bottom surface and the wall surface become vertical when shouldering. The wall surface can be formed at a desired angle with respect to the bottom surface.

  Here, in order to accurately adjust the back taper amount of the outer peripheral blade, at least one of the inner peripheral surface of the adjustment hole and the outer peripheral surface of the adjustment member is reduced toward the rear end side in the axial direction. It is desirable to have a tapered shape with a diameter. Accordingly, by inserting the adjusting member further into the axially rear end side of the end mill body from the position where at least one taper surface is in sliding contact with the other, the tip end portion of the end mill main end is deformed according to the insertion position, and the outer periphery. The back taper amount of the blade can be adjusted with high accuracy.

  In addition, the adjustment member may be inserted into the adjustment hole by press fitting, shrink fitting, cold fitting, or the like, but by inserting the adjustment member into the adjustment hole with a male and female screw portion provided between the adjustment hole, The insertion position of the end portion of the end mill body can be easily adjusted, and the back taper amount of the outer peripheral blade can be adjusted to a desired size more reliably.

  As described above, according to the present invention, the back taper amount of the outer peripheral blade formed on the outer periphery of the tip portion of the end mill body can be adjusted according to the material of the work material, cutting conditions, etc. In this case, the wall surface can be formed so as to be perpendicular to the bottom surface with high accuracy, or can be formed so as to be inclined at a desired angle.

It is a side view which shows the 1st Embodiment of this invention. It is a bottom view which shows the front end surface of embodiment shown in FIG. It is ZZ sectional drawing in FIG. It is a schematic diagram which shows the state which adjusts a back taper in embodiment shown in FIG. It is sectional drawing equivalent to ZZ sectional drawing in FIG. 2 which shows the 2nd Embodiment of this invention. When shoulder cutting is performed by a conventional end mill, (a) a cross-sectional view when the wall surface A is inclined so as to protrude toward the bottom surface B side, and (b) the wall surface A moves backward as it moves toward the bottom surface B side. It is sectional drawing at the time of inclining.

  1 to 3 show a first embodiment of the present invention. In the present embodiment, the end mill main body 1 is formed in a substantially cylindrical shape centering on the axis O with a hard material such as cemented carbide or high-speed tool steel, and a rear end portion (in FIGS. 1, 3, and 4). The upper portion) is a shank portion 2 that remains in a cylindrical shape, and the tip portion (the lower portion in FIGS. 1, 3, and 4) is a cutting blade portion 3. In such an end mill, the shank portion 2 is gripped by the main spindle by the machine tool and rotated around the axis O in the end mill rotation direction T, but is usually fed in a direction crossing the axis O and covered by the cutting edge portion 3. Cutting material is cut.

  On the outer periphery of the cutting edge portion 3 on the front end side of the end mill body 1, a chip discharge groove 4 that twists toward the rear side in the end mill rotation direction T around the axis O as it goes from the front end to the rear end side of the end mill main body 1 in the circumferential direction. A plurality of strips (four strips in this embodiment) are formed at intervals. At the intersection ridge line portion between the wall surface of the chip discharge groove 4 facing the end mill rotation direction T and the outer peripheral surface of the cutting edge portion 3, the outer periphery twisted around the axis O like the chip discharge groove 4 with the wall surface as a rake face. Each blade 5 is formed.

  Further, a concave groove-like gash 6 is formed at the tip of each chip discharge groove 4 toward the inner peripheral side. The wall of the gash 6 facing the end mill rotation direction T and the tip escape of the tip of the end mill main body 1. A bottom blade 7 is formed at the intersecting ridge line with the surface from the tip of the outer peripheral blade 5 toward the inner peripheral side with the wall surface of the gasche 6 as a scoop surface. Here, the end mill of the present embodiment is a square end mill in which these bottom blades 7 extend substantially on a plane perpendicular to the axis O so as to be substantially orthogonal to the outer peripheral blade 5.

  Further, an adjustment hole 8 is formed on the inner periphery of the cutting edge portion 3 from the front end of the end mill body 1 along the axis O toward the rear end side. The adjustment hole 8 has a circular shape centering on the axis O. In the present embodiment, as shown in FIG. 3, the adjustment hole 8 has a countersink at the opening at the end of the end mill body 1. In the direction of the axis O, the chip discharge groove 4 is formed to have a constant inner diameter from the position where the chip discharge groove 4 cuts to the outer peripheral side, but this inner diameter is smaller than the core thickness circle inscribed in the groove bottom of the chip discharge groove 4. It is said that.

  Further, a screw hole 9 having a smaller diameter than the adjustment hole 8 with the axis O as the center and having a female screw portion formed on the inner periphery is formed from the bottom of the adjustment hole 8 toward the rear end side. ing. In this embodiment, the screw hole 9 is formed directly in the end mill body 1 and extends in the direction of the axis O to the rear end side beyond the position where the chip discharge groove 4 rises and extends to the front end side of the shank portion 2. Has been.

  An adjustment member 10 is inserted into the adjustment hole 8. The adjusting member 10 includes an adjusting portion 10 </ b> A and a male screw portion 10 </ b> B that are integrally formed of a steel material or the like coaxially. The male screw portion 10 </ b> B directed toward the rear end side of the end mill body 1 is screwed into the screw hole 9. As a result, the adjustment portion 10 </ b> A is received and inserted into the adjustment hole 8. The adjusting portion 10A has a larger diameter than the male screw portion 10B. In this embodiment, the outer diameter gradually decreases at a constant rate toward the rear end side of the end mill body 1 in the axis O direction. It is said that.

  In addition, the outer diameter of the rear end side of the adjusting portion 10A on the male screw portion 10B side is made smaller than the inner diameter of the adjusting hole 8, and the maximum outer diameter of the most advanced portion is the adjusting hole 8 on the rear end side of the counterbore portion. The inner diameter is slightly larger than the inner diameter of the countersink portion. Further, the length of the adjustment portion 10A in the direction of the axis O is smaller than the depth of the adjustment hole 8, and the front end surface of the adjustment portion 10A has an engagement hole 10C such as a regular hexagonal section that engages with a work tool such as a wrench. Is formed.

  Accordingly, when such an adjustment member 10 is inserted into the adjustment hole 8 by screwing the male screw portion 10B into the screw hole 9 by engaging the working tool with the engagement hole 10C and rotating it, the adjustment portion 10A. Even if the end mill body 1 is formed of a hard material as described above by pressing the cutting edge 3 of the end mill body 1 to the outer circumference side by sliding the outer periphery of the tip end having the maximum outer diameter into contact with the inner circumference of the adjustment hole 8. Is elastically deformed, and in the present embodiment, the tip end side of the cutting blade portion 3 is expanded in diameter. Although the amount of diameter expansion depends on the original outer diameter of the cutting edge portion 3 and the inner diameter of the adjustment hole 8, it can give a back taper although the diameter is very small, about 4 to 5 μm.

  For this reason, according to the present embodiment, the material of the work material, the cutting conditions, and the like are different, and when the work material W is shouldered as shown in FIG. When the wall surface A is slightly inclined so as to protrude toward the bottom surface B side due to the fall of 1, the outer diameter D1 on the front end side of the cutting edge portion 3 is adjusted to the outer side on the rear end side as shown in FIG. By making the diameter larger than the diameter D2, it is possible to adjust the back taper amount of the outer peripheral blade 5 in the cutting blade portion 3 to correct such inclination.

  Moreover, even if the adjustment hole 8 is formed in the cutting blade portion 3 and is hollow, the adjustment member 10 is inserted into the adjustment hole 8, and the tip portion that becomes the maximum outer diameter of the adjustment portion 10 </ b> A is the adjustment hole. Since the cutting edge 3 is hollow in this manner, the rigidity of the end mill body 1 can be prevented from being lowered.

  Further, in the present embodiment, the adjustment hole 8 has a constant inner diameter, and its inner peripheral surface is a cylindrical surface centered on the axis O, while the adjustment portion 10A of the adjustment member 10 is on the rear end side in the axis O direction. The shape is a frustoconical taper that gradually decreases in diameter toward the top. Therefore, when the outer diameter D1 on the front end side of the cutting edge portion 3 is made larger than the outer diameter D2 on the rear end side as described above, the size of the outer diameter D1 is changed according to the insertion position of the adjusting portion 10A. By doing so, the back taper amount can be finely adjusted in accordance with the inclination of the wall surface A, and shoulder cutting can be performed so that the wall surface A is accurately perpendicular to the bottom surface B.

  Furthermore, in this embodiment, the adjustment member 10 is inserted into the adjustment hole 8 by screwing the male screw portion 10B into the female screw portion of the screw hole 9 formed at the bottom of the adjustment hole 8. In this respect, the adjusting member 10 is not provided with the male screw portion 10B, and thus the screw hole 9 is not formed in the adjusting hole 8, and only the adjusting portion 10A is adjusted, for example, by press fitting, shrink fitting or cold fitting. Although it is possible to adjust the back taper by inserting the back taper in this case, it is difficult to finely adjust the back taper amount depending on the insertion position of the adjusting portion 10A as described above. According to the embodiment, the back taper amount can be finely adjusted to a predetermined size with certainty by adjusting the insertion position of the adjustment portion 10A according to the screwing amount of the adjustment member 10.

  In the present embodiment, the screw hole 9 is directly formed in the end mill body 1 made of a hard material such as cemented carbide. However, such a hard material is hard while being brittle, so that there is a risk of lack of threads. Therefore, for example, the screw hole 9 is a separate member made of steel or the like, and is joined to the bottom of the adjustment hole 8 by brazing or fixed by press-fitting, shrink fitting, cold fitting, or the like. Also good.

  Next, FIG. 5 shows a second embodiment of the present invention, and the same reference numerals are assigned to parts common to the first embodiment to simplify the description. In the first embodiment, the adjustment hole 8 has a constant inner diameter, whereas in this second embodiment, the inner diameter of the adjustment hole 8 is the rear of the outer diameter of the adjustment portion 10A of the adjustment member 10 in the direction of the axis O. It is characterized by being formed so that the diameter is gradually reduced toward the rear end side at a constant rate equal to this ratio in accordance with the progressive reduction in diameter toward the end side. In addition, the counterbore part is not formed in the opening part of the adjustment hole 8. FIG.

  In such an end mill of the second embodiment, as in the first embodiment, by inserting the adjusting member 10 into the adjustment hole 8 and pressing the cutting blade portion 3 toward the outer peripheral side, Since the thickness of the portion where the cross section perpendicular to the axis O formed between the adjustment hole 8 and the core thick circle forms an annular shape becomes thicker toward the rear end side, the cutting edge portion 3 is less likely to be deformed. As shown in FIG. 4, the back taper amount of the outer peripheral blade 5 can be adjusted so that the outer diameter D1 on the front end side of the cutting blade portion 3 is larger than the outer diameter D2 on the rear end side. Further, in the second embodiment, the outer diameter of the adjusting portion 10A becomes smaller in proportion to the smaller inner diameter of the adjusting hole 8 toward the rear end side in the axis O direction. It is possible to closely contact the inner peripheral surface of the adjustment hole 8 over the entire length in the O direction, and it is possible to more reliably suppress a decrease in rigidity of the cutting edge portion 3 due to the formation of the hollow adjustment hole 8. Become.

  By the way, when the adjustment hole 8 is formed in a tapered shape in which the inner diameter gradually decreases toward the rear end side in the direction of the axis O, the adjustment member 10 has an outer peripheral surface of the adjustment portion 10A on the axis. Even when the outer peripheral blade 5 is inserted into the adjustment hole 8 even if it has a cylindrical surface centered on O or a cross section along the axis O is a convex curve such as an arc, for example, a spherical surface. The back taper amount can be adjusted. That is, it is only necessary that at least one of the inner peripheral surface of the adjustment hole 8 and the outer peripheral surface of the adjustment portion 10A of the adjustment member 10 has a tapered shape that decreases in diameter toward the rear end side in the axis O direction.

  When the inner diameter of the adjustment hole 8 is formed so as to gradually decrease toward the rear end side in the axis O direction, the maximum outer diameter of the adjustment portion 10A of the adjustment member 10 is set to the front end side of the adjustment hole 8. Although it is sufficiently smaller than the inner diameter of the adjusting hole 8, it is made larger than the rear end side of the adjusting hole 8, so that the adjusting portion 10 A is brought into sliding contact with the inner peripheral surface at the position of the adjusting hole 8 on the rear end side. The diameter of the part 3 can be increased.

  In this case, since a space is generated between the adjustment member 10 and the adjustment hole 8 on the tip side from the position where the adjustment portion 10A is in sliding contact, the diameter of the cutting edge portion 3 on the tip side from this position is not increased. Even if the diameter is increased, the amount of diameter expansion can be made smaller than that on the rear end side.

  Therefore, in 2nd Embodiment comprised in that way, when the back taper is previously given to the outer periphery blade 5 before inserting the adjustment member 10, the back taper amount can be made small. Further, when the back taper amount given in advance is small, or when the outer diameter of the outer peripheral blade 5 is constant without the back taper being given, the outer diameter D2 in FIG. 4 is the outer diameter D1. It is possible to give a reverse back taper so that the outer diameter of the outer peripheral blade 5 becomes larger as it goes to the rear end side in the axis O direction.

  For this reason, as shown in FIG. 6B, for example, even if the outer peripheral blade 5 is provided with a back taper, the end mill body 1 is less tilted than the back taper, and shouldering is performed on the work material W. When the wall surface A tilts so as to recede toward the bottom surface B side, the wall surface A can be formed to be perpendicular to the bottom surface B by adjusting the back taper amount in this way. it can. Further, in some cases, by giving a reverse back taper to the outer peripheral blade 5 as described above, a wall surface A that is inclined so as to protrude toward the bottom surface B as shown in FIG. It can also be formed intentionally with an inclination.

  On the other hand, when manufacturing the end mill as in the first and second embodiments, first, the adjustment hole 8 and the cylindrical material that becomes the end mill main body 1 before the chip discharge groove 4 and the outer peripheral blade 5 are formed are provided. By forming the screw hole 9 and screwing the adjusting member 10, a portion that becomes the cutting blade portion 3 is elastically deformed, and a back taper of about 2 to 3 μm is provided in advance so that the tip end side has a larger diameter. Therefore, a chip discharge groove 4 and an outer peripheral blade 5 with a back taper of 0 or the like may be formed at the tip of the end mill body 1.

  In the end mill manufactured in this way, if the insertion position of the adjusting portion 10A is left as it is without changing the screwing amount of the adjusting member 10, it can be used as an end mill without a back taper. If the screw is further screwed in, the back taper amount of the outer peripheral blade 5 can be adjusted so that the tip end side of the cutting blade portion 3 is expanded. On the other hand, if the adjustment member 10 is loosened, the pressure on the distal end side of the cutting blade portion 3 is relieved, and a reverse back taper can be applied to the outer peripheral blade 5 so that the diameter of the distal end side is reduced. The back taper amount can be adjusted in the range of normal, reverse and zero.

  In the first and second embodiments, the case where the present invention is applied to a square end mill in which the outer peripheral blade 5 and the bottom blade 7 are substantially orthogonal to each other has been described. For example, the outer peripheral blade 5 and the bottom blade It is also possible to apply to a radius end mill in which 7 is connected via a substantially 1/4 arc-shaped corner blade. It is also possible to adjust the taper amount by applying the present invention to a tapered blade end mill in which the outer diameter of the outer peripheral blade 5 is gradually increased toward the rear end side in the axis O direction.

DESCRIPTION OF SYMBOLS 1 End mill main body 3 Cutting edge part 4 Chip discharge groove 5 Peripheral blade 7 Bottom blade 8 Adjustment hole 9 Screw hole 10 Adjustment member 10A Adjustment part 10B Male thread part O End mill main body 1 axis T End mill rotation direction

Claims (3)

  An outer peripheral blade is formed on the outer periphery of the end portion of the end mill body having an outer cylindrical shape centered on the axis, and an adjustment hole is formed along the axis on the inner periphery of the end portion of the end mill body. An end mill, wherein an adjusting member for adjusting a back taper of the outer peripheral blade is inserted so that an outer peripheral surface thereof can be slidably contacted with an inner peripheral surface of the adjusting hole.   2. The end mill according to claim 1, wherein at least one of the inner peripheral surface of the adjustment hole and the outer peripheral surface of the adjustment member has a tapered shape that decreases in diameter toward the rear end side in the axial direction. .   The end mill according to claim 1, wherein the adjustment member is inserted into the adjustment hole by a male and female screw portion provided between the adjustment hole and the adjustment hole.

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