JP5312538B2 - Throwaway end mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a level difference of a machined wall face of a product caused by multi-stage cutting in shoulder machining or groove machining by a throw-away end mill, and thereby to provide a high quality machined wall face with increased roughness of a machined surface. <P>SOLUTION: In a cutting method for shoulder machining multi-stage cutting with respect to a cut material wall face, a throw-away tip is formed so that a rotational trajectory cross section of a major cutting edge 6 cut by a virtual flat surface including the rotary shaft 9 is formed into an approximately circular arc shape W swelled outside from both ends of a side to the center in the direction of the rotary shaft, when the throw-away tip is rotated around a rotary shaft 9 of the holder. The multi-stage cutting of the cut material wall face is performed by only a tip side of the holder out of the major cutting edge of the throw-away tip. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a throw-away end mill used as a rotary tool in a machine tool such as a machining center.

  As a throw-away end mill used as a rotary tool in machining by a machine tool such as a machining center, a throw-away end mill is known in which a throw-away tip having a substantially parallelogram shape is attached to a holder tip. The throw-away tip is arranged on the outer diameter side of the end mill as the main cutting edge on the long side, and on the tip end side of the end mill as the Saray blade on the short side, and the main cutting edge is aligned with the rotation axis of the holder. It is configured to be mounted on the holder in an inclined state called a directional rake angle.

  Conventionally, a throw-away tip with a main cutting edge formed in a straight line in plan view has been used, but if the shoulder is machined by attaching it to the holder with an axial rake angle as described above, the machining The wall surface is not a flat surface, but is a convex curved surface that bulges outward from both sides to the center, where the portion processed near the center of the main cutting edge slightly protrudes outward. In machining that places emphasis on perpendicularity, the fact that the machining wall surface becomes a convex curved surface that protrudes from both sides to the center part not only impairs the appearance quality of the product, but also requires a finishing process again. Extra processing time and processing cost were required, which was a problem in terms of processing efficiency.

  Therefore, in order to eliminate this problem and obtain a smooth processed surface, Patent Document 1 describes that the main cutting edge is configured to bulge outward in a plan view of the throw-away tip alone, and the main cutting edge of the throw-away tip. By making the intersecting ridge line of the virtual cylindrical surface with the same diameter as the processing diameter of the holder and the plane inclined at an angle corresponding to the axial rake angle as the main cutting edge shape so that the rotation trajectory of It is described that an excellent processed surface can be formed.

Japanese Patent No. 3085686

  However, when a throw-away end mill equipped with a throw-away tip with a bulging main cutting edge is used as in Patent Document 1, the dimensions of the throw-away tip are precisely controlled, and the throw-away tip is accurately attached to the holder. In this case, the rotation trajectory of the main cutting edge can be controlled to a highly accurate cylindrical surface shape over the edge of the cutting edge, but in reality, the mounting accuracy varies between the holder and the throw-away tip and the dimensional accuracy varies. For example, when the throwaway tip is mounted on the holder, there is often a difference in the radius of rotation at both ends of the main cutting edge.In such a state, when multi-stage cutting is performed by shoulder cutting or grooving, There has been a problem that a large step is formed at the joint between passes in processing of a plurality of passes on the processing surface. Also, during actual machining, the bending of the holder occurs due to the cutting load. In such a case, the throw-away tip could be attached at a position where the rotation trajectory becomes an ideal cylindrical surface shape. As a result, a step is generated on the processed wall surface. That is, it is practically impossible to obtain a processed surface with no step.

The present invention has been made in order to solve such a problem of the prior art, and in machining with a throw-away end mill, a machining wall level difference of a work material caused by multi-stage incision in shoulder machining or grooving is provided. An object of the present invention is to provide a throw-away end mill that can be made small and can be machined into a product with a machined wall surface having a higher machined surface roughness across the edge of the cutting edge.

In order to solve the above-mentioned problem, the throw-away end mill of one aspect of the present invention has a substantially parallelogram shape, has a rake face on the upper surface thereof, a relief surface on the side surface, and an intersection ridge portion on the upper surface and the side surface. A throwaway tip having a main cutting edge located on the long side of a substantially parallelogram shape and a Saray blade located on the short side adjacent to one end of the main cutting edge, and a substantially cylindrical shape, the throwaway tip is formed into the substantially circular shape. one end when axial rake angle of the cutting edge ridge line of removably and the main cutting edge to the outer circumferential position of the columnar and a holder which is mounted so as to be positive, the main cutting edge, which is a side view of the indexable insert inclined lower side in the thickness direction toward the other end from the parts, and, Sarai blade Ri Do because only a partial area of the one end portion side of the main cutting edge of the short sides, when viewed from the side the holder , Around the rotation axis of the holder When rotating the low-away tip, the rotation locus of the main cutting edge which is cut along a virtual plane including the axis of rotation with one of opposite ends of the main cutting edge is inclined so as to protrude outward than the other, It is characterized by a substantially arc shape in which the central portion bulges outward with respect to a straight line connecting the one end and the other end.

  According to this configuration, even if there is a difference in the turning radius between the main cutting edges with the throw-away tip mounted, if multi-stage cutting is performed by shoulder cutting or grooving, multiple passes will be processed. The level difference generated between the joints can be reduced, and a product with a machined wall surface with a high machined surface roughness can be obtained.

  In addition, a bulge amount w of the central portion with respect to the straight line connecting the one end and the other end of the main cutting edge is 0.02 mm to 0.06 mm, and further, the main cutting edge and the Saray blade Forming a corner R cutting edge with a radius of curvature r of 0.4 to 4.0 mm between the two, when multi-stage cutting is performed by shoulder cutting or grooving, the joint between the passes is formed by a plurality of passes This is preferable in that the level difference generated can be made smaller and a high-quality processed surface can be obtained stably.

Further, the throwaway end mill according to another aspect of the present invention has a substantially parallelogram shape, and has a rake face on the upper surface and a relief surface on the side surface, and a substantially parallelogram shape on the crossing ridge portion of the upper surface and the side surface. A throwaway tip having a main cutting edge located on the long side and a Sarai blade located on a short side adjacent to one end of the main cutting edge, and a substantially cylindrical shape, and the throwaway tip is arranged on the outer periphery of the substantially cylindrical shape. a throw-away end mill axial rake angle of the cutting edge ridge line of removably and main cutting edge has a holder which is mounted so as to be positively located, the main cutting edge, a side of the throw-away tip vision and inclined lower side in the thickness direction toward the other end from one end when the, and, Sarai blade Ri Do because only a partial area of the one end portion side of the main cutting edge of the short side, the side surface of the holder When viewed, the holder When about an axis of rotation rotates the throw-away tip, the rotation locus of the main cutting edge which is cut along a virtual plane including the rotation axis, as one of opposite ends of the main cutting edge protrudes outwardly from the other It is inclined and has a substantially arc shape in which the central portion bulges outward with respect to a straight line connecting the one end and the other end.
D: Holder processing diameter (mm),
L: length of a straight line connecting both ends of the main cutting edge (mm),
θ: Axial rake angle (°) of main cutting edge ridgeline,
X = (D− (D2−L2sin2θ) 1/2) / 2: Maximum width between a straight line connecting both ends of the main cutting edge and a virtual cylindrical surface having the same diameter as the machining diameter of the holder on the outer peripheral side from the straight line ( when a mm),, swelling amount a of the main cutting edge center portion to the straight line connecting the main cutting edge at both ends, characterized by satisfying the relationship X + 0.02 ≦ a ≦ X + 0.06.

With such a configuration, the throwaway end mill has a different holder machining diameter, throwaway tip (main cutting edge) size, and axial rake angle of the main cutting edge ridgeline when the throwaway insert is mounted on the holder. However, when the shape of the main cutting edge ridgeline is optimized and multi-step cutting is performed by shoulder cutting or grooving, the step generated at the joint between passes by processing of multiple passes can be reduced, A high-quality processed surface with a high processed surface roughness can be obtained.

According to the throwaway end mill of the present invention, it has a substantially parallelogram shape, a rake face is provided on the upper surface, a relief surface is provided on the side surface, and the long side of the substantially parallelogram shape is formed on the intersecting ridge line portion of the upper surface and the side surface. A throwaway tip having a main cutting edge and a Sarai blade located on the short side adjacent to one end of the main cutting edge and a substantially cylindrical shape, and the throwaway tip can be attached to and detached from the substantially cylindrical outer peripheral position. And a holder mounted so that the axial rake angle of the cutting edge of the main cutting edge is positive, and the main cutting edge is directed from one end to the other end when the throwaway tip is viewed from the side. inclined lower side in the thickness direction and Sarai blade Ri Do because only a partial area of the one end portion side of the main cutting edge of the short sides, when viewed from the side the holder, about an axis of rotation of the holder Rotate throwaway tip If allowed, the rotation locus of the main cutting edge which is cut along a virtual plane including the axis of rotation with one of opposite ends of the main cutting edge is inclined so as to protrude outward than the other, one end and the other Even if there is a difference in the radius of rotation at both ends of the main cutting edge with the throw-away tip attached, the shoulder and groove are machined. When the multi-stage cutting process is performed, the step formed at the joint between the passes can be reduced by the processing of a plurality of passes, so that high-quality product processing with a high processing surface roughness is possible.

It is a cross-sectional schematic diagram parallel to the said rotating shaft of the rotation locus | trajectory by the main cutting edge of the throwaway tip when the throwaway tip by embodiment of this invention is rotated around the rotating shaft of a holder. 1 is an overall perspective view of a throw-away end mill according to an embodiment of the present invention. It is a principal part side view of FIG. It is a top view of the throw away tip by this embodiment. (A) Conceptual diagram of the processing wall cross-section of the work material multi-stage cut by shoulder cutting by the throw-away end mill according to the present embodiment, (b) Work wall surface of the work material multi-stage cut by shoulder cutting by the conventional throw-away end mill FIG. (A) is a schematic perspective view when the rotation trajectory of the main cutting edge forms a cylindrical surface, (b) is a view in the B direction of (a), and (c) is a view in the C direction of (a). is there.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 to 4 show an embodiment of the present invention. FIG. 1 shows a throwaway tip (hereinafter abbreviated as a chip) 2 according to an embodiment of the present invention rotated around a rotation axis 9 of a holder 1. FIG. 2 is an overall perspective view of a throw-away end mill (hereinafter abbreviated as an end mill) 10 according to the present embodiment, FIG. 2 is a side view of the main part of FIG. 2, FIG. 4 is a plan view of the chip 2 according to the present embodiment, and FIG. 5A is a processing wall surface of a work material processed by multi-stage cutting by shoulder milling or grooving by the end mill according to the present embodiment. 6A is a schematic perspective view when the rotation locus of the main cutting edge forms a cylindrical surface, FIG. 6B is a view in the direction of arrow B in FIG. 6A, and FIG. c) is a view in the direction of the arrow C in FIG.

1 to 4, the end mill 10 according to the present embodiment includes two opposing corners of a crossed ridge formed by the side surface 3 and the upper surface 4 of the main body having a substantially parallelogram shape in plan view. A chip 2 having a corner R cutting edge 5 formed at a corner and a long side cutting edge 6 as a main cutting edge and a short side cutting edge 7 as a Saray blade on both sides of the corner R cutting edge 5 Is mounted on the holder 1. On the upper surface of the chip 2, a rake face 8 with a certain rake angle is formed along the main cutting edge 6 in order to smoothly process chips generated by end milling such as shoulder machining and groove machining. Yes.

  Further, as shown in FIG. 3, the tip 2 is mounted on the holder 1 so that the axial rake angle θ of the cutting edge ridgeline of the main cutting edge 6 is positive in order to improve the sharpness of the end milling. Yes. By the way, regarding the axial rake angle θ, if the main cutting edge ridge line is composed of one straight line in a side view of the chip (for example, see FIG. 3), the angle formed by the straight line and the holder rotation axis is If the main cutting edge ridgeline is composed of a combination of multiple straight lines or curves in the side view of the chip, both ends (boundary points with the corners) of the main cutting edge ridgeline should be straight lines. The angle between the straight line and the holder rotation axis is θ.

  In the end mill of the present invention, as shown in FIG. 1, the main cutting edge of the chip is further curved than the above-mentioned throw-away end mill of Patent Document 1, and the rotation locus of the main cutting edge 6 is not linear, but the main cutting edge. 6 has a substantially arc shape bulging outward from both ends to the center. As a result, when the tip is rotated with the tip mounted on the holder, even if there is a difference in the radius of rotation at both ends of the main cutting edge, the step that occurs at the joint between the passes due to multi-step cutting by shoulder cutting or groove processing Therefore, it is possible to process high-quality products with high surface roughness. The reason for this will be described below with reference to FIG.

FIG. 5 (a) is a conceptual diagram of a machined wall cross-section of a work material that has been multi-staged by shoulder cutting with the end mill of the present invention, and FIG. FIG. Originally, when the holder is mounted on the holder so that there is no difference in the radius of rotation at both ends of the main cutting edge, there is no step at the end. However, strictly speaking, due to variations in the mounting accuracy of the chip and the holder, variations in dimensional accuracy, etc., the end mill is often tilted so that either end of the main cutting edge protrudes toward the outer circumference. When multi-stage cutting is performed, a step is generated on the machining wall surface of the work material along with the rotation trajectory of the cutting blade for each pass. Specifically, in the state where both the product of the present invention and the conventional product are attached with an inclination of the same angle, the state of the processed surface at the end of the cutting edge becomes the shape shown in FIG. That is, for the rotation trajectories 22 and 23 of the main cutting edge indicated by the dotted lines in FIG. 5, the rotation trajectory 22 of the main cutting edge according to the present invention is more dominant than the rotation trajectory 23 of the main cutting edge according to the conventional product. As the center part of the cutting edge swells, the main cutting edge bites more into the work material wall surface, and when the multi-stage cutting process is repeated, the level difference in the machining wall surface between the passes is apparent from FIG. towards the step h ₁ of the processing wall according to the present invention product is smaller than the step h ₂ processing wall by conventional found the following machining machining walls in the end mill of the present invention, the step is small, more processing even in the processing ends It turns out that surface roughness becomes high.

  In addition, it is preferable that the magnitude | size w of the swelling of the rotation locus | trajectory of the main cutting edge 6 is 0.02 mm-0.06 mm. This is because even if there is some variation in the mounting state of the chip, the processing step can be controlled to be small, and a sufficient effect of improving the processing surface roughness can be exhibited.

  Furthermore, as shown in FIG. 1 or FIG. 3, it is possible to form a corner R cutting edge 5 having a radius of curvature r = 0.4 to 4.0 mm at a corner portion following the main cutting edge 6 at the end of the main cutting edge. This is desirable in that the level difference can be made smaller and the processed surface roughness can be increased.

Further, the end mill of the present invention has a holder machining diameter of D (mm), a length of a straight line connecting both ends of the main cutting edge is L (mm), an axial rake angle of the main cutting edge is 0 (°), The maximum width between the straight line connecting both ends of the blade and the virtual cylindrical surface having the same diameter as the processing diameter of the holder on the outer peripheral side from the straight line is X = (D− (D ² −L ² sin ² θ) ^1/2 ) / 2, when the bulging amount A (mm) of the central portion of the main cutting edge with respect to the straight line connecting both ends of the main cutting edge is
X + 0.02 ≦ A ≦ X + 0.06
By satisfying the relationship, the holder machining diameter, the throwaway tip (main cutting edge) size, and the axial rake angle of the main cutting edge ridge line when the throwaway insert is mounted on the holder are individually different. Even with the throw-away end mill, when the shape of the main cutting edge ridgeline is optimized and multi-stage cutting is performed by shoulder cutting or grooving, the level difference that occurs at the joint between passes due to the processing of multiple passes is reduced. can do. This will be described in detail with reference to FIG.

In FIG. 6A, a conventional cutting edge 17 is defined as an intersecting ridge line between the virtual cylindrical surface 15 having the same diameter as the processing diameter of the holder and the plane 16 inclined at an angle corresponding to the axial rake angle θ. Here, in FIG. 6C, which is a view in the direction of the arrow C in FIG. 6A, the maximum width of the conventional cutting edge 17 that is an arc with respect to the straight line 18 that connects both ends of the conventional cutting edge 17. Let X be
D ² = (D−2X) ² + (Lsin θ) ²
The relationship holds. That is,
X = (D− (D ² −L ² sin ² θ) ^1/2 ) / 2
In this state, the main cutting edge of the tip is arranged on the virtual cylinder, that is, the configuration shown in Patent Document 1, and as described above, the variation in the mounting accuracy between the holder and the tip and the dimensional accuracy are reduced. Due to variations, etc., there is a difference in the radius of rotation at both ends of the main cutting edge when the insert is mounted on the holder, and there are multiple passes on the machining wall surface when multi-step cutting is performed by shoulder cutting or grooving A big step will occur at the joint.

  On the other hand, in the end mill of the present invention, the bulging amount A at the center of the main cutting edge with respect to the straight line connecting both ends of the main cutting edge satisfies the relationship of X + 0.02 ≦ A ≦ X + 0.06. Thereby, the rotation trajectory of the main cutting edge is not an ideal straight line, but a substantially arc shape that swells toward the center. As a result, in the actual machining in which there is a difference in the rotation radius at both ends of the cutting edge, the step generated on the machining wall surface can be reduced as described above.

  With this relationship, the rotation trajectory of the main cutting edge is always an appropriate arc, regardless of the holder outer diameter, throw-away tip size, or axial rake angle, and a stable machined surface. Roughness can be obtained.

  As mentioned above, although embodiment of this invention was illustrated, this invention is not limited to the said embodiment, It cannot be overemphasized that it can be made arbitrary, unless it deviates from the objective of invention.

1: Holder 2: Throw away tip (chip)
3: Side surface 4: Upper surface 5: Corner R cutting blade 6: Main cutting blade 7: Saray blade (short edge cutting blade)
8: Rake face 9: Rotating shaft 10: Throw-away end mill (end mill)
14: Chip pocket 15: Virtual cylindrical surface 16: Plane inclined at an angle corresponding to the axial rake angle θ 17: Conventional cutting edge 18: Straight line connecting both ends of the conventional cutting edge 21: Work material 22: According to the present invention the main cutting edge of the machining trajectory 23: machining path of the main cutting edge by conventional w: the main cutting edge bulging amount h 1 from both end portions toward the center portion of the rotation trajectory _{of, h 2:} the step of machining the wall surface by the multi-stage scribing

Claims (4)

A main cutting edge having a substantially parallelogram shape, having a rake face on its upper surface, a flank surface on its side surface, and a main cutting edge located on the long side of the substantially parallelogram shape on the upper surface and the intersecting ridge line portion of the side surface, A throw-away tip having a Sarai blade located on the short side adjacent to one end of the main cutting edge;
A holder having a substantially cylindrical shape, the throwaway tip being detachably attached to the outer peripheral position of the substantially cylindrical shape, and attached so that the axial rake angle of the cutting edge of the main cutting edge is positive. A throwaway end mill,
The main cutting edge is inclined downward in the thickness direction as it goes from the one end to the other end when the throw-away tip is viewed from the side , and the Saray blade is formed on the short cutting edge of the main cutting edge. Ri Do since part of one end region only,
When the holder is viewed from the side, when the throw-away tip is rotated around the rotation axis of the holder, the rotation trajectory of the main cutting edge cut along a virtual plane including the rotation axis is the main cutting edge. One end of each of the two is inclined so as to protrude outward from the other, and has a substantially arc shape in which a central portion swells outward with respect to a straight line connecting the one end and the other end. Throwaway end mill.   2. The throwaway end mill according to claim 1, wherein a bulging amount w of the central portion with respect to the straight line connecting the one end portion and the other end portion of the main cutting edge is 0.02 mm to 0.06 mm. .   The throw-away end mill according to claim 1 or 2, wherein a corner R cutting edge having a radius of curvature r = 0.4 to 4.0 mm is formed between the main cutting edge and the Saray blade. A main cutting edge having a substantially parallelogram shape, having a rake face on its upper surface, a flank surface on its side surface, and a main cutting edge located on the long side of the substantially parallelogram shape on the upper surface and the intersecting ridge line portion of the side surface, A throw-away tip having a Sarai blade located on the short side adjacent to one end of the main cutting edge;
A holder having a substantially cylindrical shape, the throwaway tip being detachably attached to the outer peripheral position of the substantially cylindrical shape, and attached so that the axial rake angle of the cutting edge of the main cutting edge is positive. A throwaway end mill,
The main cutting edge is inclined downward in the thickness direction as it goes from the one end to the other end when the throw-away tip is viewed from the side , and the Saray blade is formed on the short cutting edge of the main cutting edge. Ri Do since part of one end region only,
When the holder is viewed from the side, when the throw-away tip is rotated around the rotation axis of the holder, the rotation trajectory of the main cutting edge cut along a virtual plane including the rotation axis is the main cutting edge. Is tilted so that one of both ends protrudes outward from the other, and is substantially arc-shaped with a central portion bulging outward with respect to a straight line connecting the one end and the other end,
D: Holder processing diameter (mm),
L: length of a straight line connecting both ends of the main cutting edge (mm),
θ: Axial rake angle (°) of main cutting edge ridgeline,
X = (D− (D2−L2sin2θ) 1/2) / 2: Maximum width between a straight line connecting both ends of the main cutting edge and a virtual cylindrical surface having the same diameter as the machining diameter of the holder on the outer peripheral side from the straight line ( mm),
A throw-away end mill characterized in that a bulge amount A of a central portion of the main cutting edge with respect to a straight line connecting both ends of the main cutting edge satisfies a relationship of X + 0.02 ≦ A ≦ X + 0.06.

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