JP2014188611A - End mill and manufacturing method thereof - Google Patents

Abstract

[PROBLEMS] To prevent deterioration of a machined surface roughness due to peeling of a coating film.
A margin portion 20 is provided on an outer peripheral surface of a tip end portion of an end mill body 11 and is located on a circumference centering on an axis of the end mill body 11 connected to a rear side in the end mill rotation direction T of an outer peripheral blade 16. An outer peripheral flank 21 is formed on the inner peripheral side of the end mill body 11 as it goes to the rear side in the end mill rotational direction T and toward the rear side in the end mill rotational direction T. The margin portion 20 is coated on the base material surface of the end mill main body 11. The film 22 is coated, and the coating film 22 is not coated on the base material surface of the end mill body 11 of the outer peripheral flank 21 at the boundary between the outer flank 21 and the margin 20.
[Selection] Figure 3

Description

  The present invention relates to an end mill in which a margin portion having no clearance angle is formed on the outer peripheral surface of the outer peripheral blade on the rear side in the end mill rotation direction, and a manufacturing method thereof.

  As an end mill in which such a margin portion is formed, for example, Patent Document 1 includes a cylindrical shank portion, and a blade portion having an outer peripheral blade and a bottom blade provided at one end of the shank portion. A round land having a cylindrical surface on the same surface continuous with the outer peripheral surface of the shank portion on the outer peripheral blade, that is, a margin portion having no clearance angle with respect to the outer peripheral blade is located on the rear side in the end mill rotation direction of the outer peripheral blade. What was formed in the outer peripheral surface is proposed. Further, Patent Document 1 also describes that the blade portion is coated with DLC coating, TiAlN, TiN, TiC or the like.

JP 2009-148860 A

  By the way, in an end mill coated with such a margin portion, a chip discharge groove is usually formed on the outer periphery of the tip of the base material of the cylindrical end mill body, and the wall surface and outer periphery facing the end mill rotation direction An outer peripheral edge is formed at the intersection ridge line with the surface, and the margin part is widened from the outer peripheral blade to the rear side in the end mill rotation direction, and an outer peripheral flank face toward the inner peripheral side as it goes rearward in the end mill rotation direction. Then, the blade is formed, and then the surface of the blade is coated.

  However, when such a coating is particularly based on the arc ion plating method, for example, as shown in FIG. 4, a crossed ridgeline portion 4 between the margin portion 2 of the base material surface of the end mill body 1 and the outer peripheral flank 3. As a result, the coating film 5 is covered so as to rise up at the edge portion. When such an end mill is used for cutting as it is, a compressive stress is generated in the coating film 5 by a physical vapor deposition method (PVD method) such as an arc ion plating method. As shown in FIG. 5, the stepped portion is easily peeled off to form a stepped portion, which may damage the processed surface and deteriorate the processed surface roughness.

  Further, in the coating film 5 by such an arc ion plating method, fine protrusions and fine particles having a size of about 0.3 to 5.0 μm protrude on the surface other than the edge portion as described above. In particular, since the margin portion 2 is cut while rubbing the processed surface of the work material, such fine protrusions and fine particles protrude from the coating film 5 of the margin portion 2. As a result, the roughness of the processed surface is deteriorated. On the other hand, when the surface of the coating film 5 is polished in order to remove such fine protrusions and fine particles, the rake face 6 faces the margin portion 2 and the end mill rotation direction T of the chip discharge groove. As shown in FIGS. 4 and 5, the coating film 5 covered with the outer peripheral edge 7 that is an intersecting ridge line portion with the wall surface is rounded, resulting in an increase in cutting resistance.

  The present invention has been made under such a background, and the roughness of the machined surface is deteriorated due to the peeling of the coating film coated on the base material surface of the end mill body at the crossing ridge line portion with the outer peripheral flank surface of the margin portion. A first object of the present invention is to provide an end mill that can be prevented and a method of manufacturing the end mill. Further, it is possible to prevent deterioration of the surface roughness due to fine protrusions and fine particles protruding from the coating film in the margin portion and to reduce cutting resistance. A second object is to provide an end mill capable of suppressing the increase and a method for manufacturing the end mill.

  In order to solve the above-mentioned problem and achieve the first object, the end mill of the present invention has a chip discharge groove formed on the outer periphery of the end portion of the end mill body rotated about the axis, and the end mill rotates in the chip discharge groove. An outer peripheral blade having a rake face as the wall surface is formed at a crossing ridge line portion between the wall surface facing the outer periphery and the outer peripheral surface of the end mill main body end portion, and an end mill of the outer peripheral blade is formed on the outer peripheral surface of the end mill main body front end portion. A margin part located on the circumference centered on the axis line and connected to the rear side in the rotation direction, and further to the rear side in the end mill rotation direction and further toward the rear side in the end mill rotation direction. An outer peripheral flank face toward the peripheral side is formed, and the margin portion is coated with a coating film on the surface of the base material of the end mill body. Ngumaku is characterized in that the uncoated on the surface of the base material of the end mill body in the outer peripheral flank at the boundary between the peripheral relief surface and the margin portion.

  Moreover, in the manufacturing method of the end mill of the present invention for achieving the first object, the surface of the base material of the end mill body to be rotated around the axis is coated with a coating film, and then the end mill body A margin portion is left on the outer periphery of the tip portion of the end mill, and a margin portion is left on the circumference centering on the axis, and the inner end of the end mill body is moved toward the rear side in the end mill rotation direction of the margin portion toward the rear side in the end mill rotation direction. An outer peripheral flank face toward the peripheral side is formed by removing the coating film and the base material of the end mill body.

  According to such an end mill manufacturing method, an outer peripheral flank surface is formed by removing the coating film and the base material while leaving a margin portion on the outer periphery of the end part of the end mill body whose surface is coated with the coating film. Therefore, the end mill of the present invention in which the base material surface in the margin portion is coated with the coating film while the base material surface in the boundary portion with the margin portion of the outer peripheral flank is not coated with the coating film is manufactured. Can do.

  And in the end mill of the present invention in which the coating film is not coated on the base material surface in the outer peripheral flank of the boundary portion as described above, even if the coating is by physical vapor deposition (PVD method), the boundary portion, The coating film is not formed so as to rise at the intersection ridgeline between the margin portion and the outer peripheral flank. Therefore, according to such an end mill, the coating film at the raised boundary portion is peeled off during the cutting process to form a stepped portion, thereby improving the finished surface accuracy without losing the processed surface roughness. Can be planned.

  In order to achieve the second object, the end mill of the present invention further includes a surface of the coating film polished, and the rake face at the boundary between the rake face and the margin part. The end mill main body is not coated on the surface of the base material of the end mill, and the end mill manufacturing method of the present invention further includes coating the coating film on the surface of the end mill main body. Next, the outer peripheral flank and the chip discharge groove on the end mill rotation direction side of the margin portion are removed from the outer periphery of the end portion of the end mill body, and the coating film and the base material of the end mill body are removed. And forming an outer peripheral blade having a rake face as a wall surface facing the end mill rotation direction of the chip discharge groove. To.

  In such an end mill manufacturing method, the chip discharge groove, like the outer peripheral flank, is also removed by removing the coating film and the base material of the end mill body, leaving a margin portion coated with the coating film whose surface is polished. Therefore, even in the boundary portion between the rake face and the margin portion which is the wall surface facing the end mill rotation direction side of the chip discharge groove, the base material surface of the end mill body on the rake face is not coated with the coating film. The end mill of the present invention can be manufactured.

  In such an end mill, since the surface of the coating film remaining in the margin portion is polished to remove fine protrusions and fine particles, the margin portion is cut while rubbing the processing surface of the work material. However, the roughness of the processed surface is not deteriorated, and on the contrary, the finished surface accuracy can be improved by the burnishing effect. Further, after the coating film is polished in this way, the coating film and the end mill base material are removed, so that a chip discharge groove is formed and an outer peripheral blade having a rake face as a wall surface facing the end mill rotating direction is formed. Therefore, the outer peripheral blade is not rounded, and it becomes possible to secure a sharp sharpness and reduce cutting resistance.

  As described above, according to the present invention, firstly, it is prevented that the coating surface rises at the boundary portion between the margin portion and the outer peripheral flank surface and the processing surface roughness is deteriorated due to peeling at the time of cutting. Secondly, by removing fine protrusions and fine particles on the coating film surface, it is possible to prevent the outer peripheral cutting edge from being rounded, and to improve the finished surface accuracy and reduce cutting resistance by the burnishing effect. It becomes possible to plan.

It is a side view which shows one Embodiment of the end mill of this invention. It is sectional drawing perpendicular | vertical to the axis line of the cutting blade part in embodiment shown in FIG. FIG. 3 is an enlarged cross-sectional view around an outer peripheral blade in FIG. 2. It is an expanded sectional view of the periphery of an outer peripheral blade in a conventional end mill. FIG. 5 is an enlarged cross-sectional view of the periphery of the outer peripheral blade showing a state where the coating film is peeled off at the boundary portion between the margin portion and the outer peripheral flank in the end mill shown in FIG.

  1 to 3 show an embodiment of the present invention. In the present embodiment, the end mill body 11 is formed in a substantially cylindrical shape having an axis O as a center from a base material made of a hard material such as cemented carbide or high-speed tool steel, and a rear end portion (right side portion in FIG. 1). ) Is a cylindrical shank portion 12, and a tip portion (left side portion in FIG. 1) is a cutting edge portion 13. In such an end mill, the shank portion 12 is gripped by the main spindle by the machine tool and rotated in the end mill rotation direction T around the axis O, and is usually fed in a direction crossing the axis O and is covered by the cutting edge portion 13. Cutting material is cut.

  On the outer periphery of the cutting edge portion 13 on the front end side of the end mill body 1, there is a chip discharge groove 14 that twists toward the rear side in the end mill rotation direction T around the axis O as it goes from the front end of the end mill body 11 to the rear end side. A plurality of strips (four strips in this embodiment) are formed at intervals in the direction. Further, at the intersecting ridge line portion between the wall surface of the chip discharge groove 14 facing the end mill rotation direction T and the outer peripheral surface of the cutting edge portion 13, the wall surface is used as a rake face 15 around the axis O like the chip discharge groove 14. Each of the outer peripheral blades 16 to be twisted is formed, and the rotation trajectory of the outer peripheral blades 16 about the axis O forms a single cylindrical surface P centered on the axis O as shown in FIG. .

  Further, a concave groove-like gash 17 is formed at the front end of each chip discharge groove 14 toward the inner peripheral side, and the front wall of the gash 17 facing the end mill rotation direction T and the front end relief of the end mill main body 11 tip. A bottom blade 19 is formed at the intersecting ridge line with the surface 18 from the tip of the outer peripheral blade 16 toward the inner peripheral side. Here, the end mill of the present embodiment is a square end mill in which the bottom blades 19 extend substantially on a plane perpendicular to the axis O and are substantially orthogonal to the outer peripheral blades 16. A radius end mill that is connected to the bottom blade 19 via a substantially 1/4 arc-shaped corner blade, or a ball end mill in which the rotation trajectory of the bottom blade 19 is a hemisphere having a center on the axis O. May be.

  On the other hand, the outer peripheral surface of the cutting blade portion 13 is connected to the rear side in the end mill rotation direction T of the outer peripheral blade 16 and extends on the circumference along the cylindrical surface P having the same outer diameter as the outer peripheral blade 16; An outer peripheral flank 21 is formed which extends further to the rear side of the end mill rotation direction T of the margin portion 20 and toward the inner peripheral side of the end mill main body 11 as it goes to the rear side of the end mill rotation direction T. As shown in FIG. 2, the outer peripheral flank 21 extends to the rear side in the end mill rotation direction T and then continues to the wall surface facing the rear side in the end mill rotation direction T of the chip discharge groove 14 adjacent to the rear side in the end mill rotation direction T. ing.

  As shown in FIG. 3, on the outer peripheral surface of the cutting blade portion 13, the margin portion 20 is coated with a coating film 22 on the surface of the base material of the end mill body 11, while the outer peripheral flank 21. Such a coating film 22 is not coated on the surface of the base material, and the base material is exposed as it is. Further, in the present embodiment, the rake face 15 is not covered with the coating film 22, and the base material of the end mill body 11 is also exposed.

  Here, the coating film 22 may be one or two of the Group 4a, 5a, and 6a transition elements and the Group 3b and 4b elements of the periodic table such as Ti, Al, V, Cr, Zr, and Hf. It is made of a metal carbide, nitride, oxide, carbonitride, or boride including the above, and is typically a high melting point hard film such as TiN, TiCN, AlTiN, AlCrN, AlTiSiN, AlCrSiN. Yes, it is preferably coated with a predetermined film thickness by a physical vapor deposition (PVD) method such as an ion plating method or a sputtering method, and particularly by an arc ion plating method.

  In addition, the surface of the coating film 22 is polished, whereby fine protrusions or fine particles of the high melting point hard material as described above are removed from the surface of the coating film 22, and the surface roughness is reduced. For example, the arithmetic average roughness Ra in JIS B 0601-2001 is 0.2 μm or less. Furthermore, the circumferential width of the margin portion 20 covered with such a coating film 22 is set to 0.2 mm or less.

  As shown in FIG. 3, the surface of the coating film 22 facing the rear side in the end mill rotation direction T is substantially flush with the outer peripheral flank 21 of the base material of the end mill body 11 and the end mill rotation direction of the coating film 22. The surface facing the T side is also substantially flush with the rake face 15 in the base material of the end mill body 11. Therefore, strictly speaking, the outer peripheral edge 16 is formed at the intersection ridge line portion between the surface of the coating film 22 facing the end mill rotation direction T and the outer peripheral surface, and the outer peripheral surface of the coating film 22 is the cylindrical surface P. Will be located on top.

  An embodiment of a manufacturing method of an end mill of the present invention in the case of manufacturing such an end mill will be described. In the manufacturing method of this embodiment, a columnar base material is first manufactured from the hard material as described above. The coating film 22 is coated on the entire surface. Next, the surface of the coating film 22 is polished to remove the fine protrusions or fine particles of the high melting point hard material as described above. The coating film 22 is polished by, for example, a brush containing polishing abrasive grains, polishing cloth, buffing, polishing or lapping, or fine diamond abrasive grains or the like as shot particles and sprayed with a pressurized fluid. Shot blasting is used.

  If the surface of the coating film 22 is polished in this way, the coating film 22 and the base material of the end mill body 11 are removed with a grinding wheel or the like while leaving the coating film 22 of the margin portion 20, and the cutting edge of the end mill body 11 is removed. A chip discharge groove 14 and an outer peripheral flank 21 are formed in a portion that becomes the portion 13, and an outer periphery is formed at a cross ridge line portion between the rake face 15 that is a wall surface facing the end mill rotation direction T side of the chip discharge groove 14 and the margin portion 20. The blade 16 is formed. Further, a gash 17 is formed at the tip of the chip discharge groove 14 formed in this way, and a tip flank 18 is formed at the tip of the cutting edge 13 (tip of the end mill body 11). The blade 19 is formed.

  For example, in the end mill having the above-described structure manufactured by such a manufacturing method, the margin film 20 is coated after the coating film 22 is coated on the surface of the base material of the end mill body 11 to be rotated about the axis O. By removing the coating film 22 and the base material of the end mill main body 11 so that the film 22 remains, the outer peripheral flank 21 is formed on the rear side in the end mill rotation direction T of the margin portion 20. The surface of the base material at the boundary portion of the surface 21 with the margin portion 20 is not covered with the coating film 22.

  Therefore, in such an end mill, even if the coating film 22 is formed by physical vapor deposition (PVD method) as described above, the coating film 22 is formed at the boundary between the margin portion 20 and the outer peripheral flank 21. No swell occurs, and the swelled part is easily peeled off by a compressive stress at the time of cutting and no stepped part is formed at the boundary. For this reason, the finished surface accuracy of the processed surface can be maintained without the processed surface being damaged by the stepped portion and the processed surface roughness being deteriorated.

  Further, in the manufacturing method of the present embodiment, after the coating film 22 is formed on the surface of the base material of the cylindrical end mill body 11, before the chip discharge groove 14 and the outer peripheral flank 21 are formed, the coating film 22 is formed. By polishing the surface, in particular, fine protrusions and fine particles on the surface of the coating film 22 derived from the arc ion plating method are removed. For this reason, the surface of the coating film 22 in the margin part 20 of the manufactured end mill is also a smooth surface having the above-described surface roughness by removing such fine protrusions and fine particles.

  Here, the margin portion 20 extends on the circumference along the cylindrical surface P having the same outer diameter as that of the outer peripheral blade 16 as described above, and is not given a clearance angle with respect to the outer peripheral blade 16, so The processing surface formed by cutting with the blade 16 is further rubbed. Therefore, since the coating film 22 coated on the margin portion 20 is a hard film as described above, and the surface thereof is smooth, the coating film according to the end mill of the present embodiment. The machined surface can be finished smoothly by the burnishing effect of 22, and the finished surface accuracy can be improved.

  Furthermore, in the end mill manufacturing method of this embodiment, the chip discharge groove 14 is also coated with the coating film 22 on the surface of the cylindrical base material of the end mill body 11, and the surface is polished and smoothed. It is formed by removing the coating film 22 on the end mill rotating direction T side of the margin portion 20 and the base material of the end mill body 11. For this reason, the surface of the coating film 22 in the smoothly polished margin 20 and the end mill rotation of the chip discharge groove 14 that is formed smoothly by removing the coating film 22 and the base material of the end mill body 11 by grinding or the like. A substantial outer peripheral edge 16 is formed at the intersecting ridge line portion with the wall surface facing the direction T side.

  Therefore, according to the end mill of the present embodiment manufactured in this way, it is possible to ensure sharpness without rounding the edge of the outer peripheral blade 16, thereby sharpening the cutting of the outer peripheral blade 16 and cutting. It is possible to reduce the resistance. Further, in the present embodiment, the cutting resistance can be further reduced by the smooth surface of the coating film 22 of the margin portion 20 that rubs the processed surface cut by the outer peripheral edge 16 as described above. Can do.

DESCRIPTION OF SYMBOLS 11 End mill main body 13 Cutting edge part 14 Chip discharge groove 15 Rake face 16 Peripheral edge 20 Margin part 21 Outer peripheral flank face 22 Coating film O Axis of end mill main body T End mill rotation direction

Claims (4)

  A chip discharge groove is formed on the outer periphery of the end portion of the end mill body rotated about the axis, and the wall surface is scooped at a cross ridge line portion between the wall surface of the chip discharge groove facing the end mill rotation direction and the outer peripheral surface of the end portion of the end mill body. An outer peripheral blade as a surface is formed, and on the outer peripheral surface of the tip end portion of the end mill main body, a margin portion located on a circumference centering on the axis line connected to a rear side in the end mill rotation direction of the outer peripheral blade; The margin part is further connected to the rear side in the end mill rotation direction and further toward the rear side in the end mill rotation direction, and an outer peripheral flank face toward the inner peripheral side of the end mill body is formed. The margin part has a base material for the end mill main body. On the other hand, the coating film is coated on the surface of the outer periphery, and the outer periphery of the outer periphery of the outer peripheral relief surface and the margin portion is covered with the coating film. End mill, characterized in that the uncoated on the surface of the base material of the end mill body in.   The surface of the coating film is polished, and the surface of the base material of the end mill body on the rake face is not covered even at the boundary between the rake face and the margin part. The end mill according to claim 1.   Cover the surface of the base material of the end mill body to be rotated about the axis with a coating film, and then leave a margin on the outer periphery of the end mill body on the circumference centering on the axis. The coating film and the base material of the end mill body are removed from the outer peripheral flank face toward the inner peripheral side of the end mill body toward the rear side in the end mill rotation direction toward the rear side in the end mill rotation direction of the margin portion. The manufacturing method of the end mill characterized by the above-mentioned.   After coating the surface of the base material of the end mill body with a coating film, the surface of the coating film is polished, and then on the outer periphery of the end part of the end mill body, on the outer peripheral flank and on the end mill rotation direction side of the margin part. A chip discharge groove is formed by removing the coating film and the base material of the end mill body, and an outer peripheral blade having a rake face as a wall surface facing the end mill rotation direction of the chip discharge groove is formed. The method for producing an end mill according to claim 3.

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